Styryl dyes. Synthesis and study of the solid-state [2+2] autophotocycloaddition by NMR spectroscopy and X-ray diffraction

Russian Chemical Bulletin, International Edition, Vol. 56, No. 9, pp. 1860—1883, September, 2007

1860

Styryl dyes.

Synthesis and study of the solidꢀstate [2+2] autophotocycloaddition

by NMR spectroscopy and Xꢀray diffraction*

A. I. Vedernikov,^aL. G. Kuz´mina,^bS. K. Sazonov,^aN. A. Lobova,^aP. S. Loginov,^aA. V. Churakov,^b

Yu. A. Strelenko,^cJ. A. K. Howard,^dM. V. Alfimov,^aand S. P. Gromov^a

ꢀ

^aPhotochemistry Center, Russian Academy of Sciences,

7A ul. Novatorov, 119421 Moscow, Russian Federation.

Fax: +7 (495) 936 1255. Eꢀmail: gromov@photonics.ru

^bN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,

31 Leninsky prosp., 119991 Moscow, Russian Federation.

Fax: +7 (495) 954 1279

^cN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,

47 Leninsky prosp., 119991 Moscow, Russian Federation.

Fax: +7 (499) 135 5328

^dDepartment of Chemistry, University of Durham,

South Road, Durham DH1 3LE, UK

New styryl dyes of the pyridine and benzothiazole series were synthesized with the aim of

investigating the solidꢀstate [2+2] autophotocycloaddition (PCA) reaction. The ¹H NMR

spectroscopy showed that for most of the compounds under study, the visible light irradiation

of thin polycrystalline films of the dyes affords cyclobutane derivatives. The rate of the photoꢀ

reaction depends on the structure of the dye and is higher for compounds, which contain a

short Nꢀsubstituent in the heterocyclic moiety and have strong absorption in the visible region.

Dyes bearing electronꢀreleasing substituents in the benzene ring undergo the stereospecific

PCA in the synꢀheadꢀtoꢀtail dimeric pair to give the only rctt isomer of cyclobutane derivatives.

Electronꢀwithdrawing and bulky substituents in the benzene fragment of styryl dyes extend the

range of the mutual orientations of the molecules in the dimeric pairs, resulting in the formaꢀ

tion of two or even four isomeric cyclobutanes in the PCA reactions. The structures of some

dyes were established by Xꢀray diffraction. In the overwhelming majority of the structures, one

of two packing modes, either synꢀheadꢀtoꢀtail or synꢀheadꢀtoꢀhead, with extensive stacking

interactions is observed. A rare example of the antiꢀheadꢀtoꢀhead stacking mode was found for

the dicationic dye containing the bulky N⁺(Et)Me₂substituent in the benzene ring. The

synꢀheadꢀtoꢀtail and antiꢀheadꢀtoꢀhead stacking modes can facilitate the PCA reaction due to

the close spatial proximity of the ethylenic bonds and their parallel orientation in the dimeric

pairs of the dye molecules.

Key words: styryl dyes, crown ethers, structure, [2+2] photocycloaddition, topochemical

1

reaction, cyclobutanes, Xꢀray diffraction, H NMR spectroscopy.

The photochemical [2+2] cycloaddition (PCA) reacꢀ

changing the wavelength, and, in some cases, high

stereoselectivity of PCA reactions resulting from the

preorganization of pairs of the starting structural units. It

should also be noted that the preparation of many PCA

reaction products with the use of other synthetic apꢀ

proaches presents difficulties. The PCA reactions with

compounds containing the C=C bond can proceed in

concentrated solutions, gels, and polymers, as well as in

the solid state (in polycrystalline films and single crysꢀ

tals). In some cases, the PCA reactions can proceed as

single crystal—single crystal transformations, i.e., withꢀ

tion of organic compounds was discovered in 1960s,^1,2

and interest in this reaction has been quickened in recent

years.^3—11The advantages of this method for the carꢀ

bon—carbon bond formation are the relative simplicity of

the synthesis (irradiation of samples with light of a speciꢀ

fied wavelength), the reversibility of the reaction, which

allows the regeneration of the starting compounds by

* Dedicated to Academician G. A. Abakumov on the occasion

of his 70th birthday.

Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1797—1819, September, 2007.

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1861

out degradation of single crystals.^12—15However, this

method has not gained wide acceptance because it is diffiꢀ

cult to predict the possibility of the PCA reaction proꢀ

ceeding with a particular type of unsaturated compounds

and due to the fact that these reactions produce, as a rule,

mixtures of unseparable stereoisomers.

The PCA reactions in single crystals of extended

πꢀconjugated unsaturated compounds can proceed not

only very efficient but also stereoselectively, i.e., produce

only some of the possible isomers of cyclobutane derivaꢀ

tives. This is associated with particular geometric requireꢀ

ments^11,14for the formation of the preceding dimeric pair

of the starting molecules, in which the ethylene fragments

should be arranged approximately parallel to one another

at a distance of up to 4.2 Å. The stacking interactions

between the π systems of adjacent molecules meet these

requirements. Styryl dyes, which have an extensive chain

of conjugation and contain an ethylenic bond in the

middle of this chain, hold promise for the stereoselective

solidꢀstate PCA reactions.

Earlier, we have found^16—19that supramolecular comꢀ

plexes of crownꢀcontaining styryl dyes can be involved in

the stereospecific PCA reaction in solution in the presꢀ

ence of metal or ammonium cations to form cyclobutane

derivatives (Scheme 1; examples of the preorganization of

crownꢀcontaining styryl dyes for the PCA reaction in soꢀ

lution and the stereochemistry of the products, cycloꢀ

butane derivatives, are presented). Recently, we have

found^20—23that some of these compounds, as well as

model dyes containing no crownꢀether moieties, can be

involved in topochemical PCA reactions in thin polycrysꢀ

talline films and single crystals, including those proceedꢀ

ing without degradation of the latter. We were the first to

study this area of photochemistry of styryl dyes, although

these compounds are rather easily accessible by organic

synthetic methods, and a wide range of these compounds

can be prepared by varying the nature of substituents at

the ethylenic bond. Due to the destruction of the conjuꢀ

gation chain of the styryl chromogen as a result of the

PCA reaction and, consequently, due to a strong color

contrast between the starting and final compounds,

styryl dyes can be promising reagents for the design of

reversible data recording and storage systems at the moꢀ

lecular level.

In the present study, we performed the ¹H NMR specꢀ

troscopic investigation of the ability of styryl dyes of the

pyridine (1—4) and benzothiazole (5) series to be inꢀ

volved in the [2+2] autophotocycloaddition reaction in

thin polycrystalline films depending on the structure of

the dye and determined the compositions and threeꢀdiꢀ

mensional structures of the final products (cyclobutane

derivatives). Most of the dyes were characterized by Xꢀray

diffraction, and the packing modes formed by the dyes

were analyzed in terms of the preorganization of the

dye molecules for the solidꢀstate photochemical cycloadꢀ

dition.

Scheme 1

synꢀHeadꢀtoꢀtail

dimeric complex

rctt Cyclobutane

antiꢀHeadꢀtoꢀtail

dimeric complex

rtct Cyclobutane

isomer

Pseudosandwich

rctt Cyclobutane

synꢀHeadꢀtoꢀtail

rctt Cyclobutane

synꢀheadꢀtoꢀhead complex

isomer

pseudodimeric complex

isomer

is a heterocyclic residue;

is a crownꢀether moiety with or without a metal cation;

is H₃N⁺—(CH₂)_n—NH₃

;

+

is a sulfonatoalkyl or ammonioalkyl substituent;

is an aryl group

1862

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

Vedernikov et al.

Results and Discussion

analog of iodide 1b, has been described in our earlier

study.²⁰In the present study, styryl dyes were synthesized

according to Scheme 2. Crownꢀcontaining dyes 1b—f were

prepared by the Nꢀalkylation of 4ꢀstyrylpyridines 6a,b folꢀ

Synthesis and spectroscopic studies. The synthesis of

styryl dye 1a with the perchlorate anion, which is an

Scheme 2

n = 1 (1f, 6b), 2 (1b—e, 6a)

1: R = Et (b,f), Buⁿ(c), Prⁱ(d), Me(CH₂)₁₇(e); An^–= I^–(b—d), ClO₄^–(e,f)

2, 3, 7: R¹= R²= OMe (a); R¹= NMe₂, R²= H (b); R¹= R²= H (c); R¹= OMe, R²= H (d);

R

¹= SMe, R²= H (e); R¹= R²= Cl (f); R¹= NO₂, R²= H (g); R¹= N⁺(Et)Me₂ClO₄^–, R²= H (h)

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1863

lowed by the treatment with concentrated perchloric acid

in the case of the synthesis of perchlorate salts. Comꢀ

pound 7e and new dichloroꢀsubstituted 4ꢀstyrylpyridine

7f were synthesized by the condensation of 4ꢀpicoline and

the corresponding substituted benzaldehyde in acidic conꢀ

ditions by analogy with the synthesis of related compounds

7c,d,g.²⁴Analogs of dyes 1 containing different substituꢀ

ents in the benzene fragment instead of the crownꢀether

moiety, viz., iodides 2a,b and perchlorates 3a,c—g and 5,

were synthesized by the treatment of 4ꢀstyrylpyridines

7a—g and 2ꢀstyrylbenzothiazole 8 with ethyl iodide or

ethyl tosylate followed by the ionic exchange with HClO₄

in the case of the preparation of perchlorate salts. Comꢀ

pound 7b containing the NMe₂substituent in the benꢀ

zene fragment was subjected to the double Nꢀalkylation

by fusion with an excess of EtOTs followed by the transꢀ

formation into the perchlorate salt, which resulted in the

formation of dicationic dye 3h instead of the expected

monocationic dye 3b. Dye 3b was synthesized by the ionic

exchange of iodide 2b with NaClO₄. Bis(styryl) dye 4 was

prepared by the quaternization of 4ꢀstyrylpyridine 7a with

1,4ꢀbis(bromomethyl)benzene followed by the treatment

with HClO₄.

tive, in quantitative yield (Scheme 3, type A). This prodꢀ

uct corresponds to the PCA reaction of two dye molꢀ

ecules in the synꢀheadꢀtoꢀtail dimeric pair. Isomers of

type A of cyclobutane derivatives were prepared also by

irradiation of thin polycrystalline films of styryl dyes of

the quinoline series 9a,b.²²It was hypothesized that the

ability of dyes 1a and 9a,b to be involved in the solidꢀstate

PCA reaction is determined by two factors. First, the

tendency of these dyes to form pairs of molecular cations

(stacking dimeric pairs) in a synꢀheadꢀtoꢀtail fashion due

to the pronounced intramolecular charge transfer and the

strongest intermolecular interaction between the p_zorꢀ

bitals of the conjugated fragments results in that the

ethylenic bonds are brought into proximity and are arꢀ

ranged in an antiparallel fashion. Second, the presence of

flexible crownꢀether moieties, perchlorate anions, and

solvent molecules gives rise to a loose labile shell about

the dimeric pair, which can reduce strains as a result of

substantial shifts of the atoms in the course of PCA.

An investigation of the characteristic features of PCA for

a large series of dyes 1—5 provides a deeper insight into

the factors responsible for high efficiency and stereoꢀ

selectivity of this reaction.

The structures of new compounds 1b—f, 2a, 3a—h, 4,

1

5, and 7f were determined by H NMR spectroscopy,

Scheme 3

spectrophotometry, and mass spectrometry and were conꢀ

firmed by elemental analysis. According to the NMR data,

all 4ꢀstyrylpyridines and styryl dyes were prepared in the

E configuration (³J_{transꢀCH=CH}= 15.6—16.5 Hz).

Earlier,²⁰we have demonstrated that the photoꢀ

transformation pathway of 18ꢀcrownꢀ6ꢀcontaining styryl

dye (E)ꢀ1a principally depends on its aggregation state.

is the pyridine fragment;

is the benzene fragment

We compared the ability of homologous crownꢀconꢀ

taining styryl dyes 1a—f to be involved in the PCA reacꢀ

tion under similar conditions. The influence of the length

and branching of the substituent at the N atom, the size of

the macrocycle, and the nature of the counterion on the

efficiency of the photoreaction was investigated. For this

purpose, samples of the dyes as thin polycrystalline films

on glass were irradiated with visible light for 10 h followed

by the analysis of the photolysis products by the NMR

method. These experiments showed (Table 1) that in all

cases, cyclobutane derivatives of type A were obtained as

the only photoproducts, which corresponds²⁰to the cycloꢀ

addition in synꢀheadꢀtoꢀtail dimeric pairs of these dyes.

The nature of the anion (perchlorate in 1a or iodide in 1b)

has an insignificant effect on the rate of the PCA reaction.

R = Me (9a), R + R = CH₂(CH₂OCH₂)₄CH₂(9b)

In MeCN, the Z isomer of dye 1a existing in photoꢀ

stationary equilibrium with the E isomer was obtained as

the only product. The visible light irradiation of a thin

polycrystalline film of this dye affords another product,

viz., the only rctt stereoisomer of the cyclobutane derivaꢀ

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Vedernikov et al.

Table 1. Spectroscopic characteristics of dyes 1a—f, 2a,b, 3a—h,

4, 5, and 9a,b, the ratios of the isomers of the cyclobutane

derivatives, and the degrees of conversion (x) in thin polyꢀ

crystalline films of the dyes under visible light irradiation for 10 h

the Nꢀoctadecyl substituent. The presence of this long

hydrocarbon fragment most likely ensures the preorgaꢀ

nization of the dye molecules for the PCA reaction by

assisting in bringing into proximity the polar chromophoric

fragments in a nonpolar environment. These effects of the

concentration of the reaction centers are typical of miꢀ

celles and monolayers of amphiphilic compounds.²⁵

Changes in the length of substituents (with retention of

their electronꢀdonating nature) at another end of the styryl

chromophore (in the benzene ring) have no substantial

effect on the rate of the PCA reaction. Compared to crown

ether 1a, the decrease in the size of the macrocycle in

crown ether 1f or even the replacement of the macrocycle

by two methoxy groups (compound 3a) has virtually no

influence on the high degree of conversion of the aboveꢀ

mentioned dyes into cyclobutane derivatives (87—92%

during 10 h). These results provide indirect evidence that

the perchlorate ions play a considerable role in the solidꢀ

state photoreaction. In the absence of flexible polyether

fragments, these anions can also create a rather loose

environment about the dimer pairs of cations and/or effiꢀ

ciently reduce the steric strain that appears in the course

of PCA.^20,22

Dye

λ

_max/nm

Ratio of isomers^b

A : B : C : D

x^b

(%)

(ε/L mol^–1cm^{–1 a}

)

1a

1b

1c

1d

1e

1f

2a

2b

3a

3b

3c

3d

3e

3f

3g

3h

4

5

9a ^f

9b ^f

399 (30800)

400 (28900)

401 (37300)

400 (42900)

398 (23500)^c

397 (29400)

398 (41100)

472 (37800)

397 (39900)

472 (43700)

345 (35500)

381 (36200)

393 (37100)

342 (37800)

343 (47800)

328 (39800)^d

408 (48200)^e

427 (34600)

440 (23200)

434 (33900)

1 : 0 : 0 : 0

0 : 0 : 0 : 0

1 : 0 : 0 : 0

0 : 0 : 0 : 0

1 : 0 : 0 : 0

87

91

64

44

85

88

27

0

92

0

48

88

85

77

35

0

84

70

83

1.7 : 1 : <0.1 : <0.1

2.3 : 1 : <0.1 : <0.1

1.9 : 1 : 4.7 : 2.2

0 : 0 : 0 : 0

1 : 0 : 0 : 0

The ability of related styryl dyes 2a,b and 3a—h, which

contain various substituents in the benzene ring instead of

the crownꢀether moiety and differ in the nature of the

counterion, to undergo PCA was investigated under comꢀ

parable conditions (see Table 1).

^aMeCN, C = 5•10^–5mol L^–1, ~20 °C.

1

^bFrom the H NMR spectrum.

^cCHCl₃, C = 5•10^–5mol L^–1, ~20 °C (sh ~420 nm).

Unlike dyes 1a,b, in which the influence of the

counterion is not manifested, the related pair of dyes 2a

and 3a, in which two methoxy groups reproduce, on the

whole, the electronꢀreleasing effect of the crownꢀether

moiety, shows a difference in the rate of the photoreacꢀ

tion (a noticeable decrease in the case of iodide 2a). The

absence of flexible macrocyclic fragments and, conseꢀ

quently, the absence of loose regions in the packing creꢀ

ated by these fragments can enhance the role of the anion

in the rearrangement of the environment in the course

of PCA. The spherical shape of the I^–ion and its tenꢀ

dency to form numerous secondary contacts with the nearꢀ

est atoms^26,27can hinder the rearrangement of weak inꢀ

teratomic interactions with this ion and do not allow the

latter to efficiently compensate the strain created in the

molecular packing of dye 2a by the PCA reaction. It should

be noted that the PCA reaction does not proceed at all in

single crystals of 2a (see below). In this case, a rather large

distance between the C=C bonds in the adjacent dye

molecules within the dimeric pair (4.18 Å), which is close

to the limiting value for the cycloaddition reaction, has a

considerable effect. Assuming that this dye has the same

molecular packing in films, an alternative explanation

can be given for a substantial decrease in the rate of the

photocycloaddition compared to the rate of this reaction

in perchlorate 3a, in which the aboveꢀmentioned disꢀ

tance is 3.72 Å. However, the molecular arrangement in

^dA broad charge transfer band at 470 nm (ε = 850 L mol^–1cm^–1).

^eMeCN, C = 2.5•10^–5mol L^–1, ~20 °C.

^fThe published data.²²

Apparently, the size of the anion and its ability to be

aligned to the environment, which changes in the course

of PCA, is of little importance in the case of crownꢀ

containing dyes, because the flexible crownꢀether moiꢀ

eties serves this function by providing a sufficient looseꢀ

ness of the molecular packing. The replacement of the

pyridine fragment (compound 1a) with the more extended

quinoline fragment (compound 9b) also has only a slight

effect on the rate of PCA. Other parameters important for

the photoreaction, such as the closely spaced arrangeꢀ

ment of two molecules of a styryl dye in the parallel planes

and the close proximity of their ethylenic bonds, substanꢀ

tially depend on the length and branching of the substituꢀ

ent at the N atom. For example, the presence of the

nꢀbutyl substituent in dye 1c leads to a substantial deꢀ

crease in the rate of PCA compared to dye 1b containing

the Nꢀethyl group. The branching at the first carbon atom

of the Nꢀsubstituent in crown ether 1d makes the converꢀ

sion into the cyclobutane derivative even more difficult.

Evidently, a long or bulky substituent is unfavorable for

the closely spaced arrangement of C=C bonds in the

dimeric pair of the dye. However, the steric factor is weakly

pronounced in the case of amphiphilic dye 1e containing

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1865

polycrystalline films is less rigid than that in single crysꢀ

tals, and substantial thermal vibrations of atoms and fragꢀ

ments and even the movement of molecules as a whole

with respect to each other can occur. Because of this, the

PCA reaction was observed for dye 2a. It should be noted

that the elemental analysis data for the cyclobutane deꢀ

rivatives prepared from iodides 1b,c appeared to be satisꢀ

factory for photoadducts, in which either a part or all

iodine atoms exist in the oxidized state (see the Experiꢀ

mental section). Apparently, the irradiation of dye films

reaction (see Table 1). Such a sharp change in the reactivꢀ

ity compared to related dye 3a is, apparently, attributed to

the mode of binding of two styryl moieties and the rigidity

of the paraꢀxylyl spacer. The close proximity of the catꢀ

ionic centers should hinder the formation of intramoꢀ

lecular synꢀheadꢀtoꢀhead dimeric pairs due to Coulomb

interactions between likeꢀcharged fragments. In addition,

the intramolecular formation of the cyclobutane derivaꢀ

tive in the case of compound 4 would be hindered by the

presence of the strongly strained ring containing the conꢀ

formationally rigid paraꢀxylyl moiety in the photoadduct.

It should be noted that the related bis(styryl) dye of the

pyridine series containing two 18ꢀcrownꢀ6 moieties and

the metaꢀxylyl spacer can undergo the intramolecular PCA

reaction in solution (see Scheme 1). In this case, the

preorganization of styryl chromogens into a pseudoꢀ

sandwich synꢀheadꢀtoꢀhead complex is favored by the

complexation of crownꢀether moieties of the dye with the

diammonium compound.¹⁸Apparently, the intermolecuꢀ

lar oligomerization accompanied by the formation of

dimeric pairs by the styryl fragments of the adjacent molꢀ

ecules of dye 4 through synꢀheadꢀtoꢀtail stacking interacꢀ

tions (which is more favorable in view of electrostatic

interactions) does not proceed in the solid state as well.

If this were not so, the PCA reaction in such oligomeric

structures would lead to the partial or complete polymerꢀ

ization of the dye.

Dyes 2b and 3b bearing the dimethylamino group in

the benzene ring appeared to be nonreactive under these

conditions in spite of the most considerable and efficient

absorption in the visible region among all the compounds

under study (see Table 1). As mentioned in the discussion

of the Xꢀray diffraction data, these dyes are packed excluꢀ

sively in a headꢀtoꢀhead fashion, and the PCA reaction

cannot proceed because of a large distance between the

ethylenic bonds of the adjacent molecules (>6.4 Å). Howꢀ

ever, it should be emphasized that the photostability of

styryl dyes containing the nitrogen atom conjugated with

the chromophore is, most likely, determined by the naꢀ

ture of the chromophore rather than by the packing mode.

This is evidenced by the fact that PCA does not proceed

in the related azacrownꢀcontaining dyes bearing the nitroꢀ

gen atom conjugated with the styryl chromophore, which

we have studied earlier.^21,31It was also noted that the

internal conversion with the retention of the trans conꢀ

figuration of the chromogen is the major relaxation pathꢀ

way for the excited state of dyes of type 3b,³²whereas the

efficient E→Z isomerization is typical of dyes of types 1a

and 3a.²⁰Hence, the unusual stability of such dyes is

probably attributed to the strong (compared to other

heteroatoms) electronꢀdonating properties of the nitroꢀ

gen atom, resulting in an increase in the energy of conjuꢀ

gation in the chromophore and, consequently, hindering

the chain cleavage in the course of PCA. It should be

noted that the photooxidation of the iodide ions in dye 2b,

–

is accompanied by the photooxidation of I^–to IO₃

(or oxides of another composition) with atmospheric

oxygen.^28,29Presumably, an analogous reaction slowly

proceeds in films of dye 2a, resulting in the rearrangeꢀ

ment of the molecular packing, and, apparently, proꢀ

motes the PCA reaction.

A comparison of the influence of the substituents in

the benzene rings of styryl dyes 3 on the PCA reaction

shows that the latter substantially depends on the nature

of these substituents and their size. Dyes 3a,d,e containꢀ

ing electronꢀreleasing substituents conjugated with the

chromophore undergo the most rapid phototransforꢀ

mation. Undoubtedly, this is associated with a substantial

absorption of these dyes in the visible spectral region due

to an efficient electron density transfer from the electronꢀ

releasing benzene ring to the electronꢀwithdrawing hetꢀ

erocyclic fragment.³⁰This increases the efficiency of the

photoreaction under visible light irradiation. In the case

of unsubstituted dye 3c, the degree of conversion into the

cyclobutane derivative is substantially lower in accordance

with the shift of the longꢀwavelength absorption maximum

to the nearꢀUV region compared to that for dyes 3a,d,e.

An analogous dependence is observed for dyes 3f,g,h conꢀ

taining electronꢀwithdrawing substituents. The absorpꢀ

tion maximum for the latter compounds is shifted to even

shorter wavelengths because the electron density transfer

from the benzene ring to the pyridine fragment is less

favorable than that in dye 3c (see Table 1). It should be

emphasized that the rate of the PCA reaction of dichloro

derivative 3f decreases to a lesser extent than that in the

case of dyes 3a,d,e. Apparently, the presence of a subꢀ

stituent at position 3 of the benzene ring directed away

from the line of the chromophore results in the formation

of a looser molecular packing of styryl dye 3f, which proꢀ

motes the PCA reaction. An analogous, but less proꢀ

nounced, effect is observed for 3,4ꢀdisubstituted dye 3a

compared to 4ꢀmonosubstituted dyes 3d,e. In a film

of dye 3f, the PCA reaction is accompanied by the

1

E—Z isomerization (according to the H NMR data, the

E to Z isomer ratio is 65 : 35 after irradiation for 10 h),

which indirectly confirms the looseness of the molecular

packing of this dye.

Interestingly, bis(styryl) dye 4 containing perchlorate

anions and two styryl chromogens identical to the chroꢀ

mogen of dye 3a is not involved in the solidꢀstate PCA

1866

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

Vedernikov et al.

as opposed to those in dyes 1b,c, is not observed taking

into accout that the elemental analysis data for the comꢀ

pound before and after the irradiation of a thin film for

150 h are virtually identical.

containing electronꢀwithdrawing substituents are less

stereoselective. The NMR spectra of the photolysis prodꢀ

ucts of dyes 3f,g show two main sets of signals correꢀ

sponding to the protons of two rctt isomers of cyclobutane

derivatives (Fig. 1, b). In both cases, isomer of type A

corresponding to the cycloaddition in the synꢀheadꢀtoꢀ

tail dimeric pairs (E)ꢀ3f,g was obtained as the major isoꢀ

mer (an AA´BB´ spin system for the cyclobutane protons,

Styryl dyes of the benzothiazole (5) and quinoline

(9a) series bearing two methoxy groups in the benzene

ring show a considerable decrease in the rate of the PCA

reaction in polycrystalline films compared to the rate of

the phototransformation of analogous dye 3a of the pyriꢀ

dine series (see Table 1). Apparently, this tendency can

be attributed to an increase in the steric hindrance that

appears in the course of PCA as a result of a change in the

position of the bulkier heterocycle, although the more

extended conjugated system of the benzothiazole or quinoꢀ

line moiety can partially compensate a decrease in the

flexibility of these fragments due to stronger stacking inꢀ

teractions in the dimeric pair and, consequently, the closer

proximity of the ethylenic bonds; the fact that the

Nꢀsubstituent points away from the line of the chroꢀ

mophore in compound 5 can also be responsible for the

looser packing allowing a decrease in the steric strain

upon the formation of the cyclobutane derivative.

3

two doublets of doublets with J_{cisꢀH ,H}= 8.8—9.2 Hz,

a

b

³J_{transꢀH ,H}= 5.3—6.1 Hz). The second isomer (type B)

a

b

corresponds to the PCA reaction in the synꢀheadꢀtoꢀhead

dimeric pairs (E)ꢀ3f,g (an AA´BB´ spin system, two multiꢀ

3

plets with J_{transꢀH ,H}= 6.7 Hz) (Scheme 4). The posiꢀ

tions, multiplicitie^as, and the spinꢀspin coupling constants

for the signals of the cyclobutane protons in the spectra of

the photoadducts of type B are similar to the correspondꢀ

ing characteristics of the analogous synꢀheadꢀtoꢀhead isoꢀ

mers of cyclobutane derivatives, which we prepared by

the PCA reaction in solution for the complexes of crownꢀ

containing 2ꢀstyrylbenzothiazole and a bis(styryl) dye of

the pyridine series.^18,33

b

It is important that the visible light irradiation of polyꢀ

crystalline films of most of the dyes over a long period of

time (up to 100 h) leads to the complete transformation of

the starting compounds into cyclobutane derivatives

(NMR monitoring).

Scheme 4

An analysis of the ¹H NMR spectra of the cyclobutane

derivatives showed that the photoreactions of dyes 2a and

3a,d,e bearing electronꢀreleasing substituents in the benꢀ

zene ring and of unsubstituted dye 3c proceed stereospeꢀ

cifically (Fig. 1, a). Cyclobutane derivatives of type A

were obtained as the only irradiation products of

these dyes in films, as in the case of crownꢀcontaining

dyes 1a—f (see Scheme 3). The photoreactions of dyes

A

a

5.1

5.0

4.9

4.8

δ

A

B

b

is the pyridine fragment;

is the C₆H₃R¹R²fragment

5.1

5.0

4.9

4.8

δ

The irradiation of a film of dye 3h containing the

bulky N⁺(Et)Me₂group afforded a more complex mixꢀ

ture of the major photoproducts (Scheme 5). An analysis

of the signals for the pyridine protons in the H NMR

spectrum of the photolysis product showed the presence

Fig. 1. ¹H NMR spectra (DMSOꢀd₆, 25 °C, the region of

cyclobutane protons) of the photoproducts prepared by irradiaꢀ

tion of thin films of dyes 3d (a) and 3f (b) for 10 h (cyclobutane

isomer A_3dfor compound 3d and a mixture of isomers A_3fand B_3f

in a ratio of 1.7 : 1 for compound 3f).

1

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1867

of six compounds. Two of these compounds appeared to

be the E and Z isomers of compound 3h in a ratio of 9 : 1,

the signals of the ethylene protons of the latter being

observed as two doublets at δ 6.96 and 7.26 with the

CH₂N

C

CH₂N

D

3

typical coupling constants J_cisꢀHC=CH= 12.2 Hz. As in

A

the spectra of other dyes containing electronꢀwithdrawꢀ

ing substituents, characteristic signals for the protons of

two rctt cyclobutane isomers are observed at δ 4.9—5.2

(Fig. 2), which corresponds to the cycloaddition in the

B

synꢀheadꢀtoꢀtail dimeric pairs (E)ꢀ3h (type A, ³J_{cisꢀH ,H}

=

5.2

5.0

4.8

4.6

4.4

4.2

δ

a

b

3

7.1 Hz, J_{transꢀH ,H}= 4.5 Hz) and the synꢀheadꢀtoꢀhead

Fig. 2. ¹H NMR spectrum (DMSOꢀd₆, 25 °C, the region of

cyclobutane protons) of the photoproducts prepared by irradiaꢀ

tion of a thin film of dye (E)ꢀ3h for 110 h (a mixture of rctt and

rtct cyclobutane isomers A_3h—D_3hin a ratio of 1.9 : 1 : 4.7 : 2.2).

a

b

3

dimeric pairs (type B, J_{transꢀH ,H}= 6.5 Hz). However,

these isomers were the minor p^aroducts, whereas two new

rtct cyclobutane isomers generated in the photoreaction

in the antiꢀheadꢀtoꢀtail dimeric pairs (E)ꢀ3h (type C, an

b

A₂B₂spin system, two triplets with ³J_{transꢀH ,H}_b= 9.7 Hz)

a

and the antiꢀheadꢀtoꢀhead dimeric pairs (type D, an

of the Xꢀray diffraction data). The signals for the cycloꢀ

butane protons of the isomers of types C and D are obꢀ

served at higher field (at δ 4.2—4.4; see Fig. 2) compared

to the signals of the isomers of types A and B, which is

associated with the trans arrangement of the adjacent subꢀ

stituents in the cyclobutane rings of the first two isomers.

It should be emphasized that the lowꢀintensity signals at

δ 4.1—4.4 are observed also in the spectra of irradiated

samples of dyes 3f,g, which is indicative of the formation

of cyclobutane isomers C and D.

3

AA´BB´ spin system, two multiplets with J_{transꢀH ,H}

=

10.0 Hz) were the major products. Cyclobutane d^aeri^bvaꢀ

tives C have been synthesized in our earlier study by the

photolysis of metal complexes of betaines of crownꢀconꢀ

taining styryl dyes of the benzothiazole series in solution;

the characteristics of the signals for the cyclobutane proꢀ

tons of the rtct isomers of types C and D, which were

synthesized from dye 3h, are similar to both those deꢀ

scribed in the literature^34—36and the calculated³⁷paramꢀ

eters. It should be noted that the packing mode of this dye

in the single crystals is favorable for the formation of

isomers of type D in the PCA reaction (see the discussion

The tendency of styryl dyes 3f—h containing electronꢀ

withdrawing substituents to form dimeric pairs with difꢀ

ferent mutual orientations of the E isomers is, apparently,

Scheme 5

synꢀHeadꢀtoꢀtail

synꢀHeadꢀtoꢀhead

antiꢀHeadꢀtoꢀtail

antiꢀHeadꢀtoꢀhead

dimeric pair

Cyclobutane

isomers:

is the pyridine fragment;

is the C₆H₄N⁺(Et)Me₂fragment

1868

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

Vedernikov et al.

associated with the less pronounced intramolecular charge

transfer compared to that in dyes, which contain elecꢀ

tronꢀreleasing substituents and, consequently, make the

smaller donorꢀacceptor contribution to the stacking inꢀ

teractions between the conjugated fragments. In the case

of dye 3h bearing the bulky electronꢀwithdrawing subꢀ

stituent, the parallel syn orientation of the molecules is

also hindered, resulting apparently in the predominant

formation of the crossꢀlike anti orientation with an overꢀ

lapping only in the central part of the styryl chromogens.

The photoreaction of dye 5 affords cyclobutane deꢀ

rivative A as the only product, which corresponds to the

PCA reaction proceeding in the synꢀheadꢀtoꢀtail dimeric

pair. However, as opposed to cyclobutane derivatives

based on dyes of the pyridine and quinoline series, the

rctt cyclobutane isomer derived from 5 undergoes the fast

isomerization (completed in several hours) in CD₃CN or

DMSOꢀd₆, resulting in the complete disappearance of

the isomer of type A. The analysis of the compositions of

the isomerization products presented difficulties because

of a strong overlapping of the sets of signals correspondꢀ

ing to protons of three or more new cyclobutane derivaꢀ

tives. Evidently, a rather high acidity of the protons of the

cyclobutane ring adjacent to the benzothiazolium moiꢀ

eties promotes the deprotonation of these carbon atoms

of the cyclobutane fragment followed by their inversion.

Earlier,²⁰we have observed this behavior of the cycloꢀ

butane derivative of type A prepared from dye 1a. The

presence of a base is required for the isomerization in

cyclobutane derivatives containing pyridinium fragments;

in the case of benzothiazolium derivatives, the close

proximity of the cationic center, apparently, facilitates

the deprotonation of the cyclobutane moiety.

Therefore, as follows from our investigations on

polycrystalline films of styryl dyes, to increase the effiꢀ

ciency and stereoselectivity of the visible lightꢀinduced

[2+2] photocycloaddition, the dye molecule should have

the following structural characteristics: (1) the presence

of a not too bulky heterocyclic moiety, which increases its

mobility in the course of considerable structural rearꢀ

rangements of the compound; (2) the presence of an elecꢀ

tronꢀreleasing Oꢀ or Sꢀsubstituent conjugated with the

chromophore in the benzene ring, which leads to a shift

of absorption of the dye to the visible spectral region and

is favorable for the arrangement of the dye molecules in

the synꢀheadꢀtoꢀtail dimeric pairs due to the more proꢀ

nounced intramolecular charge transfer; (3) the presence

of structural units, which can allow the reaction cenꢀ

ters to come into close proximity in the course of the

PCA reaction.

tural units at distances shorter than 4.2 Å.^11,14,38Earꢀ

lier,^{20,21,39—42}we have found that the stacking mode is

the only crystal packing for crownꢀcontaining unsaturꢀ

ated dyes. In the framework of this stacking mode, stacks

with both the centrosymmetric synꢀheadꢀtoꢀtail arrangeꢀ

ment and the translationally related synꢀ and antiꢀheadꢀ

toꢀhead arrangement of the dye molecules can exist, the

first type of stacks (with the arrangement of the molecules

suitable for the PCA reaction) being observed much more

frequently. Single crystals were grown for most of the

compounds considered in the present study. A brief analyꢀ

sis of the main packing modes and their relationship with

the reactivity of dyes in thin polycrystalline films is given

below. These packing modes were discussed in detail in

the study²³in connection with the possibility of the

topochemical [2+2] photocycloaddition reaction proceedꢀ

ing without degradation of single crystals, as has been

earlier exemplified^20,22for the single crystals of styryl

dyes 1a and 9a.

The structures of the formula units in the crystals of

dyes 1b, 2a,b, 3a—h, and 5 are shown in Figs 3 and 4.

Some of these dyes form both solvated and unsolvated

forms; benzene, MeCN, and water serve as the solvent

molecules. In all cases, the ethylenic bond in the dyes is

in the trans configuration, and the conjugated fragment is

almost planar as a whole, which is indicative of a high

degree of conjugation over the chromophore. In some

structures, the central fragment of the cation is disordered

over two positions corresponding to two s conformers

occupying the same sites in the crystal lattice. In all strucꢀ

tures, the ethylene fragment is essentially localized; the

C=C bond length varies from 1.24 to 1.37 Å, whereas the

lengths of the adjacent formally single bonds are in a

range of 1.42—1.66 Å.

Of all the crownꢀcontaining dyes synthesized in the

present study, we succeeded in growing two forms of

single crystals only of iodide 1b (yellow long blocks and

plates) in a single sample. The former type of crystals

(1b•C₆H₆•H₂O) was obtained as the major form

(~80—90%); the latter (unsolvated form 1b), as the minor

form. These forms differ in the packing mode of the dye

molecules and are examples of the two most widespread

stacking modes typical also of all other dyes under study

(except for 3c•C₆H₆and 3h). The detailed consideration

of these crystal forms is given below.

The fragment of the stacking mode in the crystals of

1b•C₆H₆•H₂O is shown in Fig. 5, a. In the crystals of this

compound, the cations of the dye are arranged in a

synꢀheadꢀtoꢀtail fashion, which is most favorable from

the standpoint of minimization of the Coulomb repulsion

between the likeꢀcharged fragments and the maximum

secondary interactions between the p_zorbitals of the conꢀ

jugated fragments. This is characteristic of unsaturated

dyes belonging to intramolecular chargeꢀtransfer systems.

The stacks run along the crystallographic b axis, and each

Xꢀray diffraction analysis. As mentioned above, the

solidꢀstate PCA reactions of unsaturated compounds can

proceed only if the necessary conditions are met, such as

the approximately parallel (or antiparallel) mutual arꢀ

rangement of the ethylene fragments of two adjacent strucꢀ

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1869

O(2)

C(15)

C(5)

C(2)

C(10)

C(9)

C(14)

C(15)

C(9)

C(8)

C(25)

C(16)

C(24)

C(4)

C(3)

C(14)

C(11)

C(4)

C(2)

C(11)

O(1)

C(5)

N(1)

C(8)

C(7)

C(13)

C(17)

O(3)

C(7)

C(13)

N(1)

C(1)

C(16)

C(17)

C(6)

C(3)

C(3S)

C(24)

O(2)

O(1)

C(6)

C(12)

O(6)

C(4S)

C(12)

O(6)

C(23)

C(1)

C(2S)

C(1S)

O(3)

C(25)

C(18)

C(19)

O(1W)

O(5)

I(1)

O(4)

C(20)

C(23)

C(22)

C(18)

C(19)

O(4)

C(5S)

C(6S)

C(20)

I(1)

C(21)

C(22)

O(5)

1b•C₆H₆•H₂O

C(21)

1b

C(2)

C(10)

C(1)

N(1)

C(9)

C(8)

C(14)

O(1)

C(3)

C(4)

C(17)

C(11)

C(4)

C(10)

C(14)

C(5)

C(17)

C(8)

C(6)

C(7)

C(6)

N(1)

C(11)

O(1)

C(12)

O(2)

C(15)

C(16)

C(12)

O(2)

C(15)

C(13)

C(16)

C(5)

C(3)

C(2)

C(13)

C(1)

O(13)

O(17)

O(12)

Cl(1)

O(16)

O(18)

I(1)

O(14)

O(15)

O(11)

2a

3a

O(1)

O(2)

C(1S)

Cl(1)

O(2)

O(3)

C(3SA)

C(2SA)

C(2S)

C(3S)

O(3)

O(4)

C(1SA)

O(4)

C(12)

C(2)

C(13)

C(1)

N(1´)

C(6)

C(2´)

C(13´)

C(12´)

C(11)

C(7´)

C(13´)

C(1)

N(1)

C(14´)

C(12)

C(11)

C(1´)

C(3)

C(6)

C(3)

C(7´)

C(8´)

C(9´)

C(10´)

C(2´)

C(7)

C(6´)

C(3´)

C(4)

C(13)

C(14)

C(6´)

C(3´)

N(1)

C(5´)

C(7)

C(8)

C(9´)

C(8)

C(5)

C(11´)

C(10)

C(4)

C(15)

C(14)

C(5)

C(10)

C(15)

C(4´)

C(9)

C(4´)

C(9)

3c

3c•0.5C₆H₆

O(11)

O(14)

C(2S)

Cl(1)

O(12)

C(1S)

C(6S)

O(13)

C(3S)

C(4S)

C(5S)

C(10)

C(4)

C(9)

C(4´)

C(5)

C(16)

C(14)

C(11)

C(5)

C(14)

C(6´)

C(7)

C(6´)

C(17)

C(4)

C(10)

C(3)

N(2)

C(3´)

N(1)

C(1)

C(9´)

C(9)

C(7)

C(8)

C(15)

N(1)

C(2´)

C(8)

C(7´)

C(6)

C(10´)

C(11)

C(12)

C(3)

C(6)

C(2)

C(1)

C(9S)

C(13)

C(11S)

C(10S)

C(8´)

C(13´)

C(15)

C(8S)

C(13)

C(9S)

C(10S)

C(4S)

C(2S)

C(7S)

C(7´)

C(11´)

C(12)

C(3S)

C(12´)

C(12S)

C(5S)

C(8S)

C(1S)

C(6S)

I(1)

C(11S)

C(12S)

C(7S)

C(5S)

3c•C₆H₆

2b•2C₆H₆

C(4S)

C(2)

C(6S)

C(1)

C(13)

C(15)

C(3S)

C(2)

C(6)

C(17)

C(12)

C(11)

C(16)

C(7´)

C(8)

C(1S)

C(17)

C(3)

C(2´)

C(2S)

C(13)

C(8)

C(3´)

C(1)

C(14)

N(2)

N(1)

N(2)

C(12)

C(11)

C(6)

C(7´)

N(1)

C(6´)

C(5)

C(7)

C(9)

C(3)

C(4)

O(3)

C(16)

C(5)

C(10)

C(14)

C(6´)

C(7)

C(9)

C(12S)

C(4)

O(2)

C(10)

C(15)

C(11S)

O(2)

Cl(1)

C(7S)

C(10S)

C(9S)

O(1)

O(4)

Cl(1)

C(8S)

O(1)

3b

O(3)

3b•2C₆H₆

Fig. 3. Structures of dyes 1b, 1b•C₆H₆•H₂O, 2a, 3a, 3с, 3с•0.5C₆H₆, 3с•C₆H₆, 2b•2C₆H₆, 3b, and 3b•2C₆H₆. For the structures of

1b•C₆H₆•H₂O, 2b•2C₆H₆, 3b, 3b•2C₆H₆, and 3с•C₆H₆, the thermal ellipsoids are drawn at the 40% probability level; for the other

structures, at the 50% probability level.

1870

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

Vedernikov et al.

C(12)

C(2)

C(16)

C(13)

C(7´)

C(1)

N(1)

C(6)

C(2)

C(3)

C(6´)

C(3´)

C(11)

O(1)

C(1)

C(15)

C(12)

C(2´)

C(4)

C(15)

C(16)

C(6)

C(3)

C(13)

C(7´)

C(8)

C(2´)

C(14)

C(7)

C(5)

C(3´)

C(5)

C(10)

C(14)

N(1)

C(11)

C(10)

C(6´)

C(4)

O(12)

C(8´)

O(18)

C(9)

C(4´)

O(17)

C(5´)

O(11)

O(15)

C(9´)

C(8)

C(7)

O(1)

C(4´)

Cl(1)

O(14)

O(16)

C(9)

O(13)

O(11)

C(3S)

C(4S)

O(13)

O(14)

Cl(1)

C(2S)

C(1S)

C(5S)

O(12)

C(6S)

3d

3d•C₆H₆

C(2)

C(16)

C(12)

C(1)

C(4´)

C(13)

C(9)

C(14)

C(6)

C(3)

C(5´)

C(5)

C(15)

C(7´)

S(1)

C(10)

C(10´)

C(11)

C(6´)

C(3´)

N(1)

C(5)

C(2´)

C(4)

C(7)

C(8´)

C(9´)

C(6´)

C(8)

C(15)

C(4)

C(3)

C(1´)

C(16)

C(8)

C(7)

O(2)

O(6)

C(3´)

O(1)

O(8)

C(9´)

C(8´)

C(10)

C(6)

C(7´)

C(13)

C(14)

N(1)

C(1)

C(9)

C(4´)

S(1)

C(12)

C(12´)

C(2´)

O(7)

O(4)

Cl(1)

O(3)

C(2)

C(13´)

O(5)

O(4)

O(3)

C(1S)

C(2S)

O(2)

Cl(1)

O(1)

C(6S)

C(5S)

C(3S)

C(4S)

3e

3e•C₆H₆

O(1)

C(2)

C(1)

N(1)

Cl(1)

O(7)

C(12)

O(2)

O(5)

C(13)

C(8)

O(2)

N(2)

C(3)

C(6)

C(7)

C(13´)

C(2)

C(14)

O(4)

C(8´)

C(7´)

O(3)

C(6)

C(3)

O(6)

C(12)

C(4)

C(1)

C(1´)

N(1)

Cl(3)

C(11)

C(15)

C(13)

C(8)

C(15)

C(5)

C(9)

O(1)

C(2´)

C(5)

C(10)

O(11)

C(3´)

C(6´)

C(11)

C(10)

Cl(2)

C(10´)

C(14)

C(9´)

N(1´)

C(7)

O(12)

O(14)

Cl(1)

O(13)

C(4)

C(5´)

C(9)

C(4´)

Cl(2´)

3f

3g

O(11)

O(13)

O(16)

Cl(1)

Cl(3A)

O(1W)

O(2W)

N(1S)

C(2S)

Cl(3B)

O(15)

O(12)

O(14)

C(17A)

C(1S)

S(1)

C(16A)

C(14B)

O(17)

C(10)

C(11)

C(15B)

C(16)

C(12)

C(4)

C(1)

C(19)

C(9)

C(8)

C(7)

C(11)

C(10)

C(3)

C(5)

N(1)

N(2)

C(13)

C(15A)

C(2)

C(9)

C(1)

C(13)

C(18)

C(2) C(6)

O(11)

O(1)

C(12)

C(7)

C(14)

O(2)

C(17)

C(16B)

C(17B)

C(3)

C(4)

O(12)

C(15)

C(8)

N(1)

C(6)

C(18)

Cl(2B)

Cl(1)

O(13)

O(14)

C(5)

Cl(2A)

C(19)

3h

5•0.5MeCN•0.5H₂O

Fig. 4. Structures of dyes 3d, 3d•C₆H₆, 3e, 3e•C₆H₆, 3f—h, and 5•0.5MeCN•0.5H₂O. For the structure of 3h, the thermal ellipsoids

are drawn at the 15% probability level; for the other structures, at the 50% probability level.

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1871

Table 2. Stacking modes in the crystal structures and the disꢀ

tances between the adjacent ethylene fragments (d₁and d₂) in

the unsolvated and solvated forms of dyes 1a,b, 2a,b, 3a—h, 5,

and 9a

C(6A)

C(7A)

C(6B)

A

a

C(7B)

Structure

Stacking mode

d₁, d₂*/Å

C(6C)

B

C(7C)

1a•H₂O

1b

1b•C₆H₆•H₂O

2а

2b•2C₆H₆

3а

3b

3b•2C₆H₆

3с

3с•0.5C₆H₆

3с•C₆H₆

3d

3d•C₆H₆

3e

3e•C₆H₆

synꢀheadꢀtoꢀtail

synꢀheadꢀtoꢀhead

synꢀheadꢀtoꢀtail

synꢀheadꢀtoꢀhead

synꢀheadꢀtoꢀtail

synꢀheadꢀtoꢀhead

synꢀheadꢀtoꢀtail

synꢀheadꢀtoꢀtail**

synꢀheadꢀtoꢀtail

synꢀheadꢀtoꢀhead

synꢀheadꢀtoꢀtail

synꢀheadꢀtoꢀhead

synꢀheadꢀtoꢀtail

antiꢀheadꢀtoꢀhead

3.55, 6.61

6.70

3.65, 5.52

4.18, 6.86

6.47

3.72, 3.73

6.87

6.48

3.66, 3.91

3.65, 5.39

3.76

3.83, 4.20

6.57

3.52, 4.76

6.66

3.62, 4.44

3.71, 4.59

3.30—3.48,

5.95

C

C(7D)

C(6D)

D

C(6A)

C(7A)

b

A

C(6B)

B

C(7B)

C(6C)

C(7C)

C

Fig. 5. Fragment of the stacking arrangement in the crystal

structures of 1b•C₆H₆•H₂O (a) and 1b (b).

3f

3g

3h

pair of the adjacent cations in the stacks (A and B, B and

C, C and D) (see Fig. 5, a) is related by a center of

symmetry. The centers of symmetry in the stacks alterꢀ

nately belong to two different crystallographic systems.

This, in fact, means that the stacks are divided into dimeric

pairs of cations (stacking dimeric pairs), in which the

distance between the ethylenic bonds d₁is shorter than

the distance between the ethylenic bonds of the adjaꢀ

cent dimeric pairs d₂(Scheme 6, a). In the crystals of

1b•C₆H₆•H₂O, the distances d₁and d₂are 3.65 and

5.52 Å, respectively. Therefore, the stacking dimeric pairs

of dye 1b are preorganized for the PCA reaction, because

the centrosymmetric arrangement of the adjacent moꢀ

lecular cations implies that the ethylenic bonds in the

cations are in the antiparallel arrangement and the disꢀ

tance between the atoms of the ethylenic bonds in the

stacking dimeric pair is substantially smaller than the upꢀ

per limiting value suitable for the PCA reaction. The effiꢀ

cient photoreaction in a thin polycrystalline film of dye

1b giving rise to centrosymmetric rctt cyclobutane isoꢀ

mers of type A (see Table 1) is indicative of a similar

crystal packing in this film.

Earlier, the same structural packing mode has been

found^20,22in the crystals of 1a•H₂O and 9a•0.5C₆H₆, for

which the cyclobutane derivatives of type A produced in

the single crystal—single crystal PCA reaction were deꢀ

tected. The stacking modes of the molecular cations in a

synꢀheadꢀtoꢀtail fashion were found also in the crystals of

2a, 3a, 3c, 3с•0.5C₆H₆, 3d—g, and 5•0.5MeCN•0.5H₂O.

For most of these crystals, the stacks of the cations are

clearly divided into stacking dimeric pairs with the disꢀ

tances d₁varying in a range of 3.49—3.83 Å (Table 2),

which correlates with the efficient and stereospecific PCA

reaction proceeding in polycrystalline films of almost all

5•0.5MeCN•

•0.5H₂O

9a•0.5C₆H₆

synꢀheadꢀtoꢀtail

3.57, 3.87

3.49, 3.76

* For the major s conformer.

** The herringboneꢀsandwich packing.

the aboveꢀmentioned dyes. The crystal of dye 2a is an

exception. In the crystal structure of 2a, the distance d₁is

4.18 Å, which is virtually equal to the upper limiting value

for the PCA reaction (4.2 Å) and is consistent with a

considerable decrease in the rate of the photoreaction in a

film of this dye (see Table 1). This difference is apparently

attributed to the structureꢀforming influence of the I^–ion,

which is prone to form C—H...I^–secondary bonds,^26,27

resulting in the orientation of the molecular cations in the

centrosymmetric dimeric pair untypical of styryl dyes.²³

It should also be noted that the molecular arrangement in

the crystals of dyes 3f,g containing electronꢀwithdrawing

substituents in the benzene ring is, apparently, different

from that in their polycrystalline films. The simultaneous

formation of isomers A and B of cyclobutane derivatives is

indicative of an either less ordered arrangement of the

molecules in the films of these compounds compared to

their single crystals or the fact that, when performing the

Xꢀray diffraction study, we did not select crystals with

other types of the molecular arrangement from a mixture

of crystals because of their poor quality.

The fragment of the stacking mode in the minor crysꢀ

tal form of unsolvated 1b is shown in Fig. 5, b. The stacks

of the molecular cations in these crystals are translationally

related and belong to the second most abundant packing

1872

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

Vedernikov et al.

Scheme 6

Note. The stacking arrangement of the dye cations in the crystals of 1b•C₆H₆•H₂O (a) and 1b (b) represented in two ways: the crownꢀ

ether moieties are indicated by ovals, the conjugated fragments are shown by lines, T are translations along the crystallographic axis,

are the centers of symmetry, and d₁and d₂are the distances between the ethylene fragments.

mode of styryl dyes, synꢀheadꢀtoꢀhead. In these stacks,

the distances between the like atoms of adjacent cations,

for example, between cations A and B, B and C, are equal

(see Fig. 5, b), i.e., the stacks are not divided into dimeric

pairs (see Scheme 6, b). The translational relation beꢀ

tween the adjacent cations in the stack implies the parallel

mutual arrangement of their C=C bonds. However, the

cations are strongly shifted in the parallel planes with

respect to each other due to minimization of the Coulomb

repulsions between the likeꢀcharged fragments with the

partial retention of stacking interactions between the conꢀ

jugated systems of the cations. This shift of the adjacent

molecular cations in the stack results in an increase in the

distance between the ethylene fragments, which is far

outside the aboveꢀmentioned region suitable for the PCA

reaction (d₁= 6.70 Å). Actually, the prolonged irradiaꢀ

tion of the crystals of dye 1b does not lead to changes in

their structure and quality, which is indicative of the abꢀ

sence of the photoreaction, as opposed to the crystals of

1b•C₆H₆•H₂O, which undergo degradation under visible

light as a result of the PCA reaction.²³

An analogous synꢀheadꢀtoꢀhead packing mode was

found in the crystals of 2b•2C₆H₆, 3b, 3b•2C₆H₆,

3d•C₆H₆, and 3e•C₆H₆. In all cases, the distances beꢀ

tween the adjacent ethylenic bonds are in a range of

6.47—6.87 Å (see Table 2), which is unfavorable for the

PCA reaction. For dyes 2b and 3b bearing the dimethylꢀ

amino group in the benzene ring, this type of the crystal

packing is, apparently, the most typical because it is indeꢀ

pendent of the nature of the counterion or the presence of

solvent molecule in the unit cell. The fact that the photoꢀ

reaction does not proceed in polycrystalline films of these

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1873

compounds may be associated with the absence of the

geometric conditions favorable for the PCA reaction, alꢀ

though other factors may be responsible for high stability

of dyes with this structure to light (see the discussion of

the results of NMR spectroscopy). As can be exemplified

by dyes 3d,e, the highestꢀquality crystals grown from a

benzeneꢀcontaining mixture of solvents consist of stacks

of translationally related molecules, which is unfavorable

for the PCA transformation.

A

C(6A)

C(7A)

C(6B)

C(7B)

B

C

C(6C)

C(7C)

The following two types of crystals of dye 3c were

grown from a benzeneꢀcontaining solvent mixture: crysꢀ

tals of hemisolvate 3с•0.5C₆H₆stable on storage under

solventꢀfree conditions and crystals of monosolvate

3с•C₆H₆, which undergo rapid degradation as a result of

erosion. The sandwichꢀherringbone packing mode obꢀ

served in the latter crystals is rare for styryl dyes. Earlier,

we have found this packing mode only in one neutral

precursor of styryl dyes, viz., dimethoxyꢀsubstituted

4ꢀstyrylquinoline.²²In the crystals of 3с•C₆H₆, the catꢀ

ions of the dye form centrosymmetric synꢀheadꢀtoꢀtail

dimeric pairs with the possible efficient stacking interacꢀ

tions in the pairs but without these stacking interactions

between the dimeric pairs (Scheme 7). The distance beꢀ

tween the C=C bonds of two molecular cations in the

dimeric pair (d₁= 3.76 Å) and their antiparallel orientaꢀ

tion implies that in this case, like in the crystals of 3c and

3с•0.5C₆H₆,²³the dye molecules are preorganized for the

PCA reaction giving rise to a cyclobutane derivative of

type A.

C(6D)

C(7D)

D

E

C(7E)

C(7F)

C(6E)

C(6F)

F

Fig. 6. Fragment of the crystal packing of dye 3h. The disorder of

the N(Et)Me₂substituent is omitted.

described as stacks running along the a axis, and the stacks

are divided into antiꢀheadꢀtoꢀhead dimeric pairs of catꢀ

ions A and B, C and D, E and F (Fig. 6). The mean planes

of the conjugated fragments of two molecular cations in

the dimeric pair are almost parallel (the dihedral angle

is 2°), and the carbon atoms of the ethylene fragments are

spaced by 3.30—3.48 Å. As can be seen from Fig. 7, the

ethylene fragments of the adjacent cations of 3h in the

dimeric pair are in a slightly staggered conformation. The

angle of their mutual twisting is ~24°, which differs from

the ideal value for the PCA reaction (0°; the parallel oriꢀ

entation). Cations B and C, D and E from the adjacent

dimeric pairs are projected onto one another only by the

benzene rings, but the spatial arrangement of these benꢀ

Scheme 7

N(2)

N(1A)

Note. The sandwichꢀherringbone arrangement

of the dye cations in the crystals of 1c•C₆H₆: the lines show

the side projection of the conjugated fragment of the dye,

are the centers of symmetry.

C(6)

C(7A)

C(7)

C(6A)

The unusual molecular packing was found in the crysꢀ

tals of styryl dye 3h. Apparently, the presence of the double

positive charge on the organic cation and the bulky

N(Et)Me₂substituent in the benzene ring hinder the forꢀ

mation of both the centrosymmetric packing mode and

the packing mode consisting of translationally related

molecules. The crystal packing of 3h can be arbitrarily

N(1)

N(2A)

Fig. 7. Mutual projection of two cations of dye 3h in the dimeric

pair. Hydrogen atoms are omitted.

1874

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

Vedernikov et al.

1

made based on twoꢀdimensional homonuclear H—¹H COSY

spectra.

zene rings substantially deviates from the parallel arrangeꢀ

ment (the dihedral angle between the benzene rings is 22°).

This is a principally new packing mode, which has not

been observed earlier in the crystals of styryl and butadienyl

dyes. The adjacent cations in the stack are related by

alternating twofold axes along the crystallographic b and

c axes. In this stack, the preorganization of the structural

units differs from those shown in Schemes 6 and 7, and

this arrangement should lead to the formation of the new

rtct isomer of the cyclobutane derivative (type D, see

above) in the PCA reaction.

It should be emphasized that our Xꢀray diffraction

studies of the possibility of the PCA reaction proceeding

without degradation of single crystals for all new dyes

considered in the present study were successful only for

the crystals of 3с•0.5C₆H₆and 3h.²³The [2+2] autoꢀ

photocycloaddition of these compounds affords cycloꢀ

butane derivatives, viz., the rctt isomer of type A and the

rtct isomer of type D in the case of 3c•0.5C₆H₆and 3h,

respectively.

To summarize, the investigation of the solidꢀstate

[2+2] autophotocycloaddition for a series of styryl dyes

showed that, in most cases, the visible light irradiation

leads to the efficient and stereospecific formation of

rctt isomers of 1,2,3,4ꢀtetrasubstituted cyclobutanes.

A high rate of the photoreaction is favored by the presꢀ

ence of a short Nꢀalkyl substituent in the heterocyclic

moiety of the dye, the electronꢀreleasing alkoxy or

alkylsulfanyl substituent in the benzene ring, and perꢀ

chlorate ions. The Xꢀray diffraction study revealed the

presence of almost exclusively the stacking modes for the

styryl dyes under consideration, among which synꢀheadꢀ

toꢀtail packing modes favorable for the PCA reactions are

observed much more often than headꢀtoꢀhead packing

modes. Due to this fact, this class of compounds holds

promise for the design of reversible data recording and

storage systems at the molecular level.

4ꢀPicoline, 3,4ꢀdichlorobenzaldehyde, 4ꢀ(methylsulfanyl)ꢀ

benzaldehyde, iodoethane, 1ꢀiodobutane, 2ꢀiodopropane, 1ꢀbroꢀ

mooctadecane, ethyl pꢀtoluenesulfonate, 1,4ꢀdi(bromoꢀ

methyl)benzene, and 70% perchloric acid (Aldrich) were used

without additional purification. 4ꢀ[(E)ꢀ2ꢀ(2,3,5,6,8,9,11,12,

14,15ꢀDecahydrobenzoꢀ1,4,7,10,13,16ꢀhexaoxacyclooctaꢀ

decinꢀ18ꢀyl)ꢀ1ꢀethenyl]ꢀ1ꢀethylpyridinium perchlorate (1a),²⁰

4ꢀ[(E)ꢀ2ꢀ(2,3,5,6,8,9,11,12,14,15ꢀdecahydrobenzoꢀ

1,4,7,10,13,16ꢀhexaoxacyclooctadecinꢀ18ꢀyl)ꢀ1ꢀethenyl]pyriꢀ

dine (6a),²⁰4ꢀ[(E)ꢀ2ꢀ(2,3,5,6,8,9,11,12ꢀoctahydrobenzoꢀ

1,4,7,10,13ꢀpentaoxacyclopentadecinꢀ15ꢀyl)ꢀ1ꢀethenyl]pyridine

(6b),⁴³4ꢀ[(E)ꢀ2ꢀ(3,4ꢀdimethoxyphenyl)ꢀ1ꢀethenyl]pyridine

(7a),⁴³N,NꢀdimethylꢀNꢀ{4ꢀ[(E)ꢀ2ꢀ(4ꢀpyridyl)ꢀ1ꢀethenyl]pheꢀ

nyl}amine (7b),⁴⁴4ꢀ[(E)ꢀ2ꢀphenylꢀ1ꢀethenyl]pyridine (7c),²⁴

4ꢀ[(E)ꢀ2ꢀ(4ꢀmethoxyphenyl)ꢀ1ꢀethenyl]pyridine

(7d),²⁴

4ꢀ[(E)ꢀ2ꢀ(4ꢀnitrophenyl)ꢀ1ꢀethenyl]pyridine (7g),²⁴and

2ꢀ[(E)ꢀ2ꢀ(3,4ꢀdimethoxyphenyl)ꢀ1ꢀethenyl]ꢀ1,3ꢀbenzothiazole

(8)⁴⁵were synthesized according to known procedures.

Synthesis of styryl dyes 1b—d and 2a,b (general procedure).

A solution of 4ꢀstyrylpyridine 6a or 7a,b (0.5 mmol) and

iodoethane, 1ꢀiodobutane, or 2ꢀiodopropane (3.0 mmol) in

dichloromethane (5—10 mL) was kept in the dark at ~20 °C for

2—4 weeks. The solvent was removed in vacuo, and the residue

was extracted with hot benzene (10 mL). The undissolved comꢀ

pound was filtered off, washed with benzene (2×3 mL), and

dried. The UV spectroscopic data for the dyes are given in

Table 1.

4ꢀ[(E)ꢀ2ꢀ(2,3,5,6,8,9,11,12,14,15ꢀDecahydrobenzoꢀ

1,4,7,10,13,16ꢀhexaoxacyclooctadecinꢀ18ꢀyl)ꢀ1ꢀethenyl]ꢀ1ꢀ

ethylpyridinium iodide (1b) was obtained in 92% yield as a yellow

powder, m.p. 210—213 °C. Found (%): C, 52.36; H, 5.77;

N, 2.50. C₂₅H₃₄INO₆. Calculated (%): C, 52.55; H, 6.00;

N, 2.45. ¹H NMR, δ: 1.53 (t, 3 H, Me, J = 7.3 Hz); 3.54 (s, 4 H,

2 CH₂O); 3.57 and 3.63 (both m, 4 H each, 4 CH₂O); 3.78 and

3.81 (both m, 2 H each, 2 CH₂CH₂OAr); 4.17 and 4.19 (both m,

2 H each, 2 CH₂OAr); 4.52 (q, 2 H, CH₂N, J = 7.3 Hz); 7.08 (d,

1 H, H(5´), J = 8.4 Hz); 7.29 (br.d, 1 H, H(6´), J = 8.4 Hz);

7.40 (br.s, 1 H, H(2´)); 7.42 (d, 1 H, H_a, J = 16.2 Hz); 7.96 (d,

1 H, H_b, J = 16.2 Hz); 8.16 (d, 2 H, H(3), H(5), J = 6.7 Hz);

8.92 (d, 2 H, H(2), H(6), J = 6.7 Hz).

1ꢀButylꢀ4ꢀ[(E)ꢀ2ꢀ(2,3,5,6,8,9,11,12,14,15ꢀdecahydroꢀ

benzoꢀ1,4,7,10,13,16ꢀhexaoxacyclooctadecinꢀ18ꢀyl)ꢀ1ꢀ

ethenyl]pyridinium iodide (1c) was obtained in 88% yield as a

yellow powder, m.p. 182—184 °C. Found (%): C, 53.97; H, 6.07;

N, 2.21. C₂₇H₃₈INO₆. Calculated (%): C, 54.09; H, 6.39;

Experimental

The melting points (uncorrected) were measured in capilꢀ

laries on a MelꢀTemp II instrument. The mass spectra were

obtained on a Finnigan MAT 8430 instrument using a direct

inlet system; the ionization energy was 70 eV. The elemental

analysis was carried out in the Laboratory of Microanalysis of

the A. N. Nesmeyanov Institute of Organoelement Compounds

of the Russian Academy of Sciences (Moscow). The absorption

spectra of solutions in acetonitrile or chloroform were meaꢀ

sured on a UVꢀ3101PC spectrophotometer (Shimadzu) in the

200—600 nm region (with a step of 0.5 nm) in 1 cm quartz cells.

The ¹H NMR spectra were recorded on a Bruker DRX500 specꢀ

trometer (500.13 MHz) in DMSOꢀd₆at 21—30 °C using the

residual signals of the undeuterated solvent as the internal stanꢀ

dard (δ_H2.50). The chemical shifts and spinꢀspin coupling conꢀ

stants were measured with an accuracy of 0.01 ppm and 0.1 Hz,

respectively. The assignment of the signals for the protons was

1

N, 2.34. H NMR, δ: 0.93 (t, 3 H, Me, J = 7.4 Hz); 1.32 (m,

2 H, CH₂Me); 1.90 (m, 2 H, CH₂CH₂N); 3.54 (s, 4 H, 2 CH₂O);

3.57 and 3.63 (both m, 4 H each, 4 CH₂O); 3.78 and 3.81

(both m, 2 H each, 2 CH₂CH₂OAr); 4.17 and 4.20 (both m,

2 H each, 2 CH₂OAr); 4.48 (t, 2 H, CH₂N, J = 7.4 Hz); 7.08 (d,

1 H, H(5´), J = 8.4 Hz); 7.29 (dd, 1 H, H(6´), J = 8.4 Hz, J =

1.8 Hz); 7.40 (br.s, 1 H, H(2´)); 7.42 (d, 1 H, H_a, J = 16.2 Hz);

7.96 (d, 1 H, H_b, J = 16.2 Hz); 8.16 (d, 2 H, H(3), H(5), J =

6.9 Hz); 8.91 (d, 2 H, H(2), H(6), J = 6.9 Hz).

4ꢀ[(E)ꢀ2ꢀ(2,3,5,6,8,9,11,12,14,15ꢀDecahydrobenzoꢀ

1,4,7,10,13,16ꢀhexaoxacyclooctadecinꢀ18ꢀyl)ꢀ1ꢀethenyl]ꢀ1ꢀ

isopropylpyridinium iodide (1d) was obtained in 31% yield as a

yellow powder, m.p. 178—180 °C. Found (%): C, 53.04; H, 6.02;

N, 2.49. C₂₆H₃₆INO₆. Calculated (%): C, 53.34; H, 6.20;

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1875

N, 2.39. ¹H NMR, δ: 1.60 (d, 6 H, Me₂CH, J = 6.7 Hz); 3.54 (s,

4 H, 2 CH₂O); 3.57 and 3.63 (both m, 4 H each, 4 CH₂O); 3.78

and 3.81 (both m, 2 H each, 2 CH₂CH₂OAr); 4.17 and 4.19

(both m, 2 H each, 2 CH₂OAr); 4.90 (sept, 1 H, CHMe₂, J =

6.7 Hz); 7.08 (d, 1 H, H(5´), J = 8.4 Hz); 7.29 (dd, 1 H, H(6´),

J = 8.4 Hz, J = 1.6 Hz); 7.41 (d, 1 H, H(2´), J = 1.6 Hz); 7.43

(d, 1 H, H_a, J = 16.2 Hz); 7.98 (d, 1 H, H_b, J = 16.2 Hz); 8.16

(d, 2 H, H(3), H(5), J = 6.8 Hz); 9.00 (d, 2 H, H(2), H(6),

J = 6.8 Hz).

A 10% NaOH solution was added to the aqueous phase

(to pH > 9). The precipitate that formed was filtered off and

recrystallized from EtOH. Compounds 7e,f were obtained as

yellowish powders.

4ꢀ{(E)ꢀ2ꢀ[4ꢀ(Methylsulfanyl)phenyl]ꢀ1ꢀethenyl}pyridine (7e)

was obtained in 51% yield, m.p. 155—157 °C (cf. lit. data⁴⁶: m.p.

118—120 °C). Found (%): C, 72.77; H, 5.43. C₁₄H₁₃NS•

•0.25H₂O. Calculated (%): C, 72.53; H, 5.87. ¹H NMR, δ: 2.50

(s, 3 H, Me); 7.21 (d, 1 H, H_a, J = 16.4 Hz); 7.29 (d, 2 H, H(3´),

H(5´), J = 8.3 Hz); 7.51 (d, 1 H, H_b, J = 16.4 Hz); 7.54 (d, 2 H,

H(3), H(5), J = 5.4 Hz); 7.60 (d, 2 H, H(2´), H(6´), J =

8.3 Hz); 8.53 (d, 2 H, H(2), H(6), J = 5.4 Hz). MS, m/z (I_rel(%)):

227 [M]⁺(100), 226 (32), 182 (31), 181 (37), 180 (82), 179 (32),

168 (19), 167 (22), 152 (22), 69 (18). UV (MeCN), λ_max/nm (ε):

331 (33900).

4ꢀ[(E)ꢀ2ꢀ(3,4ꢀDimethoxyphenyl)ꢀ1ꢀethenyl]ꢀ1ꢀethylpyriꢀ

dinium iodide (2a) was obtained in 98% yield as a yellow powder,

m.p. 233—235 °C (with decomp.). Found (%): C, 51.18; H, 5.07;

N, 3.34. C₁₇H₂₀INO₂. Calculated (%): C, 51.40; H, 5.08;

1

N, 3.53. H NMR, δ: 1.53 (t, 3 H, Me, J = 7.3 Hz); 3.84 and

3.86 (both s, 3 H each, 2 MeO); 4.51 (q, 2 H, CH₂, J = 7.3 Hz);

7.09 (d, 1 H, H(5´), J = 8.3 Hz); 7.30 (br.d, 1 H, H(6´), J =

8.3 Hz); 7.40 (br.s, 1 H, H(2´)); 7.42 (d, 1 H, H_a, J = 16.4 Hz);

7.98 (d, 1 H, H_b, J = 16.4 Hz); 8.17 (d, 2 H, H(3), H(5), J =

6.6 Hz); 8.92 (d, 2 H, H(2), H(6), J = 6.6 Hz).

4ꢀ[(E)ꢀ2ꢀ(3,4ꢀDichlorophenyl)ꢀ1ꢀethenyl]pyridine (7f) was

obtained in 49% yield, m.p. 100—101 °C. Found (%): C, 60.55;

H, 3.75; N, 5.37. C₁₃H₉Cl₂N•0.5H₂O. Calculated (%): C, 60.26;

1

H, 3.89; N, 5.41. H NMR, δ: 7.40 (d, 1 H, H_a, J = 16.2 Hz);

4ꢀ{(E)ꢀ2ꢀ[4ꢀ(Dimethylamino)phenyl]ꢀ1ꢀethenyl}ꢀ1ꢀethylpyriꢀ

dinium iodide (2b) was obtained in 94% yield as a darkꢀred powꢀ

der, m.p. 250—253 °C (from a MeCN—benzene mixture) (cf. lit.

data³²: m.p. 244—246 °C). Found (%): C, 53.57; H, 5.54;

N, 7.19. C₁₇H₂₁IN₂. Calculated (%): C, 53.69; H, 5.57; N, 7.37.

¹H NMR, δ: 1.51 (t, 3 H, Me, J = 7.3 Hz); 3.03 (s, 6 H, Me₂N);

4.45 (q, 2 H, CH₂, J = 7.3 Hz); 6.80 (d, 2 H, H(3´), H(5´), J =

8.9 Hz); 7.19 (d, 1 H, H_a, J = 16.1 Hz); 7.60 (d, 2 H, H(2´),

H(6´), J = 8.9 Hz); 7.93 (d, 1 H, H_b, J = 16.1 Hz); 8.07 (d, 2 H,

H(3), H(5), J = 6.9 Hz); 8.80 (d, 2 H, H(2), H(6), J = 6.9 Hz).

4ꢀ[(E)ꢀ2ꢀ(2,3,5,6,8,9,11,12,14,15ꢀDecahydrobenzoꢀ

1,4,7,10,13,16ꢀhexaoxacyclooctadecinꢀ18ꢀyl)ꢀ1ꢀethenyl]ꢀ1ꢀ

octadecylpyridinium perchlorate (1e). A mixture of 4ꢀstyrylꢀ

pyridine 6a (100 mg, 0.24 mmol) and 1ꢀbromooctadecane

(80 mg, 0.24 mmol) was heated in the dark at 140 °C (oil bath)

for 3 h. The reaction mixture was heated with ethyl acetate

(20 mL) and then cooled to ~20 °C. The undissolved compound

was filtered off and dried. Bromide of the dye was obtained in a

yield of 118 mg (0.16 mmol, 66%) as a yellowꢀorange powder,

m.p. 165—167 °C. The bromide was dissolved in a minimum

amount of hot anhydrous EtOH, 70% perchloric acid (28 µL,

0.32 mmol) was added, the mixture was cooled to –10 °C, and

the precipitate was filtered off, washed with cold anhydrous

EtOH (5 mL), and dried. Compound 1e was obtained in a yield

of 114 mg (62%) as a yellow powder, m.p. 162—164 °C.

Found (%): C, 64.10; H, 8.81; N, 1.81. C₄₁H₆₆ClNO₁₀. Calcuꢀ

lated (%): C, 64.08; H, 8.66; N, 1.82. ¹H NMR, δ: 0.85 (t, 3 H,

Me, J = 6.6 Hz); 1.23 (s, 26 H, (CH₂)₁₃); 1.23—1.30 (m, 4 H,

2 CH₂); 1.90 (m, 2 H, CH₂CH₂N); 3.54 (s, 4 H, 2 CH₂O); 3.57

and 3.63 (both m, 4 H each, 4 CH₂O); 3.78 and 3.81 (both m,

2 H each, 2 CH₂CH₂OAr); 4.17 (m, 4 H, 2 CH₂OAr); 4.46 (t,

2 H, CH₂N, J = 7.5 Hz); 7.07 (d, 1 H, H(5´), J = 8.6 Hz); 7.28

(br.d, 1 H, H(6´), J = 8.6 Hz); 7.39 (br.s, 1 H, H(2´)); 7.39 (d,

1 H, H_a, J = 15.9 Hz); 7.94 (d, 1 H, H_b, J = 15.9 Hz); 8.14 (d,

2 H, H(3), H(5), J = 6.6 Hz); 8.88 (d, 2 H, H(2), H(6),

J = 6.6 Hz).

7.54 (d, 1 H, H_b, J = 16.2 Hz); 7.55 (d, 2 H, H(3), H(5), J =

6.4 Hz); 7.65 (dd, 1 H, H(6´), J = 8.1 Hz, J = 1.9 Hz); 7.69 (d,

1 H, H(5´), J = 8.1 Hz); 7.97 (d, 1 H, H(2´), J = 1.9 Hz); 8.58

(d, 2 H, H(2), H(6), J = 6.4 Hz). MS, m/z (I_rel(%)): 253 [M]⁺

(2 ³⁷Cl) (37), 251 [M]⁺(³⁵Cl, ³⁷Cl) (80), 250 (31), 249 [M]⁺

(2 ³⁵Cl) (100), 248 (25), 216 (21), 214 (44), 148 (23), 69 (31), 57

(22), 55 (22). UV (MeCN), λ_max/nm (ε): 299 (22300).

Synthesis of styryl dyes 1f, 3a,c—h, and 5 (general proceꢀ

dure). A mixture of 4ꢀstyrylpyridine 6b or 7a—g or 2ꢀstyrylꢀ

benzothiazole 8 (0.5 mmol) and ethyl pꢀtoluenesulfonate

(1.5 mmol in the case of 6b, 7a,c—g, and 8 or 2.0 mmol in the

case of 7b) was heated in the dark at 120 °C (oil bath) for 2 h (6b,

7a,c—g, 8) or 20 h (7b). The reaction mixture was extracted

with hot benzene (10—15 mL). The undissolved compound was

separated by decantation and dissolved in MeOH (5 mL). Then

70% perchloric acid (1.0 mmol in the case of 6b, 7a,c—g, and 8

or 1.5 mmol in the case of 7b) was added. The mixture

was cooled to –10 °C, and the precipitate that formed was

filtered off, washed with cold MeOH (2×2 mL), and dried. The

UV spectroscopic data for these dyes are given in Table 1.

1ꢀEthylꢀ4ꢀ[(E)ꢀ2ꢀ(2,3,5,6,8,9,11,12ꢀoctahydrobenzoꢀ

1,4,7,10,13ꢀpentaoxacyclopentadecinꢀ15ꢀyl)ꢀ1ꢀethenyl]pyridiꢀ

nium perchlorate (1f) was obtained in 84% yield as a yellow

powder, m.p. 209—211 °C. Found (%): C, 55.46; H, 6.01;

N, 2.74. C₂₃H₃₀ClNO₉. Calculated (%): C, 55.26; H, 6.05;

1

N, 2.80. H NMR, δ: 1.53 (t, 3 H, Me, J = 7.3 Hz); 3.63 (m,

8 H, 4 CH₂O); 3.79 and 3.81 (both m, 2 H each, 2 CH₂CH₂OAr);

4.13 (m, 4 H, 2 CH₂OAr); 4.50 (q, 2 H, CH₂N, J = 7.3 Hz);

7.06 (d, 1 H, H(5´), J = 8.1 Hz); 7.28 (dd, 1 H, H(6´), J =

8.1 Hz, J = 1.9 Hz); 7.38 (d, 1 H, H_a, J = 16.4 Hz); 7.39 (d, 1 H,

H(2´), J = 1.9 Hz); 7.94 (d, 1 H, H_b, J = 16.4 Hz); 8.14 (d, 2 H,

H(3), H(5), J = 7.1 Hz); 8.90 (d, 2 H, H(2), H(6), J = 7.1 Hz).

4ꢀ[(E)ꢀ2ꢀ(3,4ꢀDimethoxyphenyl)ꢀ1ꢀethenyl]ꢀ1ꢀethylpyriꢀ

dinium perchlorate (3a) was obtained in 74% yield as a yellow

powder, m.p. 224—226 °C (with decomp.). Found (%): C, 55.37;

H, 5.33; N, 3.85. C₁₇H₂₀ClNO₆. Calculated (%): C, 55.21;

1

Synthesis of 4ꢀstyrylpyridines 7e,f (general procedure). A soꢀ

lution of 4ꢀpicoline (1.81 mL, 0.02 mol) and 4ꢀ(methylꢀ

sulfanyl)benzaldehyde or 3,4ꢀdichlorobenzaldehyde (0.02 mol)

in acetic anhydride (3.6 mL) was heated at 140 °C (oil bath)

for 16 h. Then the reaction mixture was cooled, poured into

water (150 mL), and extracted with benzene (3×30 mL).

H, 5.45; N, 3.79. H NMR, δ: 1.53 (t, 3 H, Me, J = 7.3 Hz);

3.83 and 3.85 (both s, 3 H each, 2 MeO); 4.51 (q, 2 H, CH₂, J =

7.3 Hz); 7.08 (d, 1 H, H(5´), J = 8.3 Hz); 7.30 (dd, 1 H, H(6´),

J = 8.3 Hz, J = 1.8 Hz); 7.38 (br.s, 1 H, H(2´)); 7.40 (d, 1 H, H_a,

J = 16.5 Hz); 7.96 (d, 1 H, H_b, J = 16.5 Hz); 8.16 (d, 2 H, H(3),

H(5), J = 6.7 Hz); 8.90 (d, 2 H, H(2), H(6), J = 6.7 Hz).

1876

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

Vedernikov et al.

1ꢀEthylꢀ4ꢀ[(E)ꢀ2ꢀphenylꢀ1ꢀethenyl]pyridinium perchlorate

(3c) was obtained in 76% yield as yellowish crystals, m.p.

142—144 °C. Found (%): C, 58.18; H, 5.14; N, 4.23.

C₁₅H₁₆ClNO₄. Calculated (%): C, 58.16; H, 5.21; N, 4.52.

¹H NMR, δ: 1.54 (t, 3 H, Me, J = 7.3 Hz); 4.54 (q, 2 H, CH₂,

J = 7.3 Hz); 7.47 (t, 1 H, H(4´), J = 7.2 Hz); 7.50 (t, 2 H, H(3´),

H(5´), J = 7.2 Hz); 7.54 (d, 1 H, H_a, J = 16.3 Hz); 7.77 (d, 2 H,

H(2´), H(6´), J = 7.4 Hz); 8.03 (d, 1 H, H_b, J = 16.3 Hz); 8.26

(d, 2 H, H(3), H(5), J = 6.5 Hz); 8.98 (d, 2 H, H(2), H(6),

J = 6.5 Hz).

1ꢀEthylꢀ4ꢀ[(E)ꢀ2ꢀ(4ꢀmethoxyphenyl)ꢀ1ꢀethenyl]pyridinium

perchlorate (3d) was obtained in 87% yield as a yellow powder,

m.p. 158—160 °C. Found (%): C, 56.88; H, 5.48; N, 3.99.

C₁₆H₁₈ClNO₅. Calculated (%): C, 56.56; H, 5.34; N, 4.12.

¹H NMR, δ: 1.53 (t, 3 H, Me, J = 7.3 Hz); 3.84 (s, 3 H, MeO);

4.51 (q, 2 H, CH₂, J = 7.3 Hz); 7.08 (d, 2 H, H(3´), H(5´), J =

8.8 Hz); 7.38 (d, 1 H, H_a, J = 16.3 Hz); 7.73 (d, 2 H,

H(2´), H(6´), J = 8.8 Hz); 7.99 (d, 1 H, H_b, J = 16.3 Hz); 8.18

(d, 2 H, H(3), H(5), J = 6.7 Hz); 8.92 (d, 2 H, H(2), H(6),

J = 6.7 Hz).

1ꢀEthylꢀ4ꢀ{(E)ꢀ2ꢀ[4ꢀ(methylsulfanyl)phenyl]ꢀ1ꢀethenyl}pyriꢀ

dinium perchlorate (3e) was obtained in 76% yield as a yellow

powder, m.p. 193—195 °C. Found (%): C, 54.06; H, 5.12;

N, 3.74. C₁₆H₁₈ClNO₄S. Calculated (%): C, 54.01; H, 5.10;

N, 3.94. ¹H NMR, δ: 1.54 (t, 3 H, Me, J = 7.3 Hz); 2.55 (s, 3 H,

MeS); 4.52 (q, 2 H, CH₂, J = 7.3 Hz); 7.38 (d, 2 H, H(3´),

H(5´), J = 8.3 Hz); 7.48 (d, 1 H, H_a, J = 16.4); 7.70 (d, 2 H,

H(2´), H(6´), J = 8.3 Hz); 7.99 (d, 1 H, H_b, J = 16.4 Hz); 8.21

(d, 2 H, H(3), H(5), J = 6.5 Hz); 8.94 (d, 2 H, H(2), H(6),

J = 6.5 Hz).

4ꢀ[(E)ꢀ2ꢀ(3,4ꢀDichlorophenyl)ꢀ1ꢀethenyl]ꢀ1ꢀethylpyridinium

perchlorate (3f) was obtained in 44% yield as a yellowish powꢀ

der, m.p. 133—135 °C. Found (%): C, 47.47; H, 3.46; N, 3.67.

C₁₅H₁₄Cl₃NO₄. Calculated (%): C, 47.58; H, 3.73; N, 3.70.

¹H NMR, δ: 1.54 (t, 3 H, Me, J = 7.3 Hz); 4.55 (q, 2 H, CH₂,

J = 7.3 Hz); 7.66 (d, 1 H, H_a, J = 16.4 Hz); 7.72 (dd, 1 H,

H(6´), J = 8.4 Hz, J = 1.9 Hz); 7.80 (d, 1 H, H(5´), J = 8.4 Hz);

7.99 (d, 1 H, H_b, J = 16.4 Hz); 8.06 (d, 1 H, H(2´), J = 1.9 Hz);

8.22 (d, 2 H, H(3), H(5), J = 6.8 Hz); 9.02 (d, 2 H, H(2), H(6),

J = 6.8 Hz).

1ꢀEthylꢀ4ꢀ[(E)ꢀ2ꢀ(4ꢀnitrophenyl)ꢀ1ꢀethenyl]pyridinium perꢀ

chlorate (3g) was obtained in 59% yield as a creamꢀcolored

powder, m.p. 173—175 °C. Found (%): C, 51.09; H, 4.15;

N, 7.94. C₁₅H₁₅ClN₂O₆. Calculated (%): C, 50.79; H, 4.26;

N, 7.90. ¹H NMR, δ: 1.56 (t, 3 H, Me, J = 7.3 Hz); 4.57 (q, 2 H,

CH₂, J = 7.3 Hz); 7.77 (d, 1 H, H_a, J = 16.5 Hz); 8.01 (d, 2 H,

H(2´), H(6´), J = 8.7 Hz); 8.13 (d, 1 H, H_b, J = 16.5 Hz); 8.32

(d, 2 H, H(3), H(5), J = 6.6 Hz); 8.36 (d, 2 H, H(3´), H(5´), J =

8.7 Hz); 9.05 (d, 2 H, H(2), H(6), J = 6.6 Hz).

1ꢀEthylꢀ4ꢀ{(E)ꢀ2ꢀ(4ꢀ[ethyl(dimethyl)ammonio]phenyl)ꢀ1ꢀ

ethenyl}pyridinium diperchlorate (3h) was obtained in 78% yield

as a pinkish powder, m.p. >270 °C (with decomp.). Found (%):

C, 47.15; H, 5.70; N, 5.60. C₁₉H₂₆Cl₂N₂O₈. Calculated (%):

C, 47.41; H, 5.45; N, 5.82. ¹H NMR, δ: 1.01 (t, 3 H,

MeCH₂NMe₂, J = 7.2 Hz); 1.55 (t, 3 H, MeCH₂N, J = 7.3 Hz);

3.59 (s, 6 H, Me₂N); 3.95 (q, 2 H, MeCH₂NMe₂, J = 7.2 Hz);

4.56 (q, 2 H, MeCH₂N, J = 7.3 Hz); 7.69 (d, 1 H, H_a, J =

16.2 Hz); 7.97 and 8.00 (both d, 2 H each, H(2´), H(6´) and

H(3´), H(5´), J = 9.3 Hz, J = 9.3 Hz); 8.07 (d, 1 H, H_b, J =

16.2 Hz); 8.26 (d, 2 H, H(3), H(5), J = 6.7 Hz); 9.03 (d, 2 H,

H(2), H(6), J = 6.7 Hz).

2ꢀ[(E)ꢀ2ꢀ(3,4ꢀDimethoxyphenyl)ꢀ1ꢀethenyl]ꢀ3ꢀethylꢀ1,3ꢀ

benzothiazolꢀ3ꢀium perchlorate (5) was obtained in 61% yield as

an orange powder, m.p. 236—239 °C (with decomp.). Found (%):

C, 53.48; H, 4.60; N, 3.02. C₁₉H₂₀ClNO₆S. Calculated (%):

1

C, 53.58; H, 4.73; N, 3.29. H NMR, δ: 1.48 (t, 3 H, Me, J =

7.3 Hz); 3.89 and 3.90 (both s, 3 H each, 2 MeO); 4.97 (q, 2 H,

CH₂, J = 7.3 Hz); 7.16 (d, 1 H, H(5´), J = 8.7 Hz); 7.68 (br.s,

1 H, H(2´)); 7.69 (br.d, 1 H, H(6´), J = 8.7 Hz); 7.78 (m, 1 H,

H(6)); 7.87 (m, 1 H, H(5)); 7.87 (d, 1 H, H_a, J = 15.6 Hz); 8.20

(d, 1 H, H_b, J = 15.6 Hz); 8.27 (d, 1 H, H(4), J = 8.7 Hz); 8.42

(d, 1 H, H(7), J = 8.1 Hz).

4ꢀ{(E)ꢀ2ꢀ[4ꢀ(Dimethylamino)phenyl]ꢀ1ꢀethenyl}ꢀ1ꢀethylꢀ

pyridinium perchlorate (3b). A solution of NaClO₄(43 mg,

0.35 mmol) in MeOH (1 mL) was added to a solution of iodide 2b

(110 mg, 0.29 mmol) in MeOH (4 mL). The reaction mixture

was cooled to –10 °C, and the precipitate was filtered off, washed

with cold MeOH (2×1 mL), and dried. Compound 3b was obꢀ

tained in a yield of 91 mg (89%) as brown crystals, m.p.

214—217 °C (with decomp.). Found (%): C, 57.99; H, 6.20;

N, 7.79. C₁₇H₂₁ClN₂O₄. Calculated (%): C, 57.87; H, 6.00;

N, 7.94. ¹H NMR, δ: 1.50 (t, 3 H, Me, J = 7.3 Hz); 3.02 (s, 6 H,

Me₂N); 4.44 (q, 2 H, CH₂, J = 7.3 Hz); 6.79 (d, 2 H, H(3´),

H(5´), J = 9.3 Hz); 7.18 (d, 1 H, H_a, J = 16.2 Hz); 7.60 (d, 2 H,

H(2´), H(6´), J = 9.3 Hz); 7.92 (d, 1 H, H_b, J = 16.2 Hz); 8.06

(d, 2 H, H(3), H(5), J = 7.0 Hz); 8.78 (d, 2 H, H(2), H(6),

J = 7.0 Hz).

4ꢀ[(E)ꢀ2ꢀ(3,4ꢀDimethoxyphenyl)ꢀ1ꢀethenyl]ꢀ1ꢀ{4ꢀ[4ꢀ(Eꢀ2ꢀ

(3,4ꢀdimethoxyphenyl)ꢀ1ꢀethenyl)pyridiniomethyl]benzyl}pyriꢀ

dinium diperchlorate (4). A solution of 4ꢀstyrylpyridine 7a

(100 mg, 0.42 mmol) and 1,4ꢀdi(bromomethyl)benzene (50 mg,

0.19 mmol) in anhydrous EtOH (10 mL) was heated (oil bath)

in the dark at 80 °C for 22 h. After cooling to ~20 °C, the

precipitate was filtered off, and dibromide of the dye was obꢀ

tained in a yield of 58 mg. The dibromide was dissolved with

heating in a mixture of EtOH (~15 mL) and a minimum amount

of water. Then 70% perchloric acid (28 µL, 0.32 mmol) was

added, the mixture was cooled to –10 °C, and the precipitate

that formed was filtered off, washed with cold EtOH (2 mL),

and dried. Compound 4 was obtained in a yield of 50 mg (37%)

as orange crystals, m.p. 310—312 °C (with decomp.). Found (%):

C, 56.10; H, 4.91; N, 3.38. C₃₈H₃₈Cl₂N₂O₁₂•1.5H₂O. Calcuꢀ

lated (%): C, 56.16; H, 5.09; N, 3.45. ¹H NMR, δ: 3.82 and 3.84

(both s, 6 H each, 4 MeO); 5.71 (s, 4 H, 2 CH₂); 7.07 (d, 2 H,

2 H(5´), J = 8.6 Hz); 7.28 (dd, 2 H, 2 H(6´), J = 8.6 Hz, J =

1.8 Hz); 7.37 (d, 2 H, 2 H(2´), J = 1.8 Hz); 7.40 (d, 2 H, 2 H_a,

J = 16.4 Hz); 7.59 (s, 4 H, C₆H₄); 7.96 (d, 2 H, 2 H_b, J =

16.4 Hz); 8.17 (d, 4 H, 2 H(3), 2 H(5), J = 6.8 Hz); 8.98 (d, 4 H,

2 H(2), 2 H(6), J = 6.8 Hz).

Synthesis of cyclobutane derivatives from dyes 1a—f, 2a,

3a,c—h, and 5 (general procedure). A solution of dye 1a—f, 2a,

3a,c—h, or 5 (15 µmol) in MeCN (0.5 mL; in the case of 1e in

chloroform (0.5 mL)) was concentrated in a 10 cm Petri dish

until a thin polycrystalline film of the dye formed. The sample

thus prepared was irradiated with unfiltered light from a 60 W

incandescent bulb from a distance of 15 cm for 10—100 h,

dissolved in MeCN (except for the sample of dye 5, which was

collected mechanically), and concentrated in vacuo. The comꢀ

positions of the products and the degrees of conversion into

1

cyclobutane derivatives were analyzed based on the H NMR

spectroscopic data by comparing the integrated intensities of the

signals for the protons. In the case of formation of a single

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1877

isomer, the elemental analysis data are given. The results of

experiments, in which the exposure time was 10 h, are presented

in Table 1.

rꢀ4ꢀ[cꢀ2,tꢀ4ꢀDi(2,3,5,6,8,9,11,12,14,15ꢀdecahydrobenzoꢀ

1,4,7,10,13,16ꢀhexaoxacyclooctadecinꢀ18ꢀyl)ꢀtꢀ3ꢀ(1ꢀethylpyriꢀ

8 H, 4 CH₂O); 3.53—3.63 (m, 16 H, 8 CH₂O); 3.71 and 3.74

(both m, 4 H each, 4 CH₂CH₂OAr); 3.94 and 4.00 (both m,

4 H each, 4 CH₂OAr); 4.46 (t, 4 H, 2 CH₂N, J = 7.0 Hz); 4.78

(dd, 2 H, 2 CHAr, J = 8.9 Hz, J = 7.7 Hz); 4.87 (dd, 2 H,

2 CHPy, J = 8.9 Hz, J = 7.7 Hz); 6.71 (s, 4 H, 2 H(5´), 2 H(6´));

6.85 (s, 2 H, 2 H(2´)); 7.91 (d, 4 H, 2 H(3), 2 H(5), J = 6.1 Hz);

8.87 (d, 4 H, 2 H(2), 2 H(6), J = 6.1 Hz).

1ꢀEthylꢀrꢀ4ꢀ[tꢀ3ꢀ(1ꢀethylpyridiniumꢀ4ꢀyl)ꢀcꢀ2,tꢀ4ꢀ

di(2,3,5,6,8,9,11,12ꢀoctahydrobenzoꢀ1,4,7,10,13ꢀpentaoxaꢀ

cyclopentadecinꢀ15ꢀyl)cyclobutyl]pyridinium diperchlorate (A_1f,

rctt isomer of the cyclobutane derivative from compound 1f,

type A) was prepared as a yellowish powder, m.p. >150 °C

(with decomp.). Found (%): C, 53.83; H, 6.01; N, 2.83.

C₄₆H₆₀Cl₂N₂O₁₈•1.5H₂O. Calculated (%): C, 53.80; H, 6.18;

N, 2.73. ¹H NMR, δ: 1.42 (t, 6 H, 2 Me, J = 7.3 Hz); 3.55—3.62

(m, 16 H, 8 CH₂O); 3.70 and 3.73 (both m, 4 H each,

4 CH₂CH₂OAr); 3.92 and 3.94 (both m, 4 H each, 4 CH₂OAr);

4.49 (q, 4 H, 2 CH₂N, J = 7.3 Hz); 4.78 (dd, 2 H, 2 CHAr,

J = 8.2, J = 7.7 Hz); 4.88 (dd, 2 H, 2 CHPy, J = 8.2 Hz, J =

7.7 Hz); 6.76 (s, 4 H, 2 H(5´), 2 H(6´)); 6.83 (s, 2 H, 2 H(2´));

7.94 (d, 4 H, 2 H(3), 2 H(5), J = 6.8 Hz); 8.89 (d, 4 H, 2 H(2),

2 H(6), J = 6.8 Hz).

diniumꢀ4ꢀyl)cyclobutyl]ꢀ1ꢀethylpyridinium diperchlorate (A_1a

,

rctt isomer of the cyclobutane derivative from compound 1a,

type A) has been described earlier.²⁰

rꢀ4ꢀ[cꢀ2,tꢀ4ꢀDi(2,3,5,6,8,9,11,12,14,15ꢀdecahydrobenzoꢀ

1,4,7,10,13,16ꢀhexaoxacyclooctadecinꢀ18ꢀyl)ꢀtꢀ3ꢀ(1ꢀethylpyriꢀ

diniumꢀ4ꢀyl)cyclobutyl]ꢀ1ꢀethylpyridinium diiodate (A_1b, rctt isoꢀ

mer of the cyclobutane derivative from compound 1b, type A)

was prepared as a paleꢀyellow powder, m.p. 105—107 °C.

Found (%): C, 48.65; H, 5.27; N, 2.28. C₅₀H₆₈N₂O₁₂•(IO₃)₂.

Calculated (%): C, 48.47; H, 5.53; N, 2.26. ¹H NMR, δ: 1.43 (t,

6 H, 2 Me, J = 7.3 Hz); 3.51 (s, 8 H, 4 CH₂O); 3.52—3.61

(m, 16 H, 8 CH₂O); 3.69 and 3.72 (both m, 4 H each,

4 CH₂CH₂OAr); 3.95 and 3.98 (both m, 4 H each, 4 CH₂OAr);

4.50 (q, 4 H, 2 CH₂N, J = 7.3 Hz); 4.79 (dd, 2 H, 2 CHAr, J =

9.0 Hz, J = 7.5 Hz); 4.89 (dd, 2 H, 2 CHPy, J = 9.0 Hz, J =

7.5 Hz); 6.77 (s, 4 H, 2 H(5´), 2 H(6´)); 6.83 (s, 2 H, 2 H(2´));

7.94 (d, 4 H, 2 H(3), 2 H(5), J = 6.7 Hz); 8.89 (d, 4 H, 2 H(2),

2 H(6), J = 6.7 Hz).

1ꢀButylꢀrꢀ4ꢀ[tꢀ3ꢀ(1ꢀbutylpyridiniumꢀ4ꢀyl)ꢀcꢀ2,tꢀ4ꢀ

di(2,3,5,6,8,9,11,12,14,15ꢀdecahydrobenzoꢀ1,4,7,10,13,16ꢀ

hexaoxacyclooctadecinꢀ18ꢀyl)cyclobutyl]pyridinium iodide/iodate

(A_1c, rctt isomer of the cyclobutane derivative from compound 1c,

type A) was prepared as a paleꢀyellow powder. Found (%):

C, 51.40; H, 6.20; N, 2.09. C₅₄H₇₆N₂O₁₂•I_0.7(IO₃)_1.3. Calcuꢀ

lated (%): C, 51.42; H, 6.07; N, 2.22. ¹H NMR, δ: 0.85 (t, 6 H,

2 Me, J = 7.3 Hz); 1.12 (m, 4 H, 2 CH₂Me); 1.77 (m, 4 H,

2 CH₂CH₂N); 3.52 (s, 8 H, 4 CH₂O); 3.53—3.62 (m, 16 H,

8 CH₂O); 3.70 and 3.73 (both m, 4 H each, 4 CH₂CH₂OAr);

3.94 and 4.00 (both m, 4 H each, 4 CH₂OAr); 4.47 (t, 4 H,

2 CH₂N, J = 7.0 Hz); 4.81 (dd, 2 H, 2 CHAr, J = 8.8 Hz, J =

8.3 Hz); 4.90 (dd, 2 H, 2 CHPy, J = 8.8 Hz, J = 8.3 Hz); 6.73

(br.d, 2 H, 2 H(6´), J = 8.5 Hz); 6.75 (d, 2 H, 2 H(5´), J =

8.5 Hz); 6.85 (br.s, 2 H, 2 H(2´)); 7.94 (d, 4 H, 2 H(3), 2 H(5),

J = 6.7 Hz); 8.87 (d, 4 H, 2 H(2), 2 H(6), J = 6.7 Hz).

rꢀ4ꢀ[cꢀ2,tꢀ4ꢀDi(2,3,5,6,8,9,11,12,14,15ꢀdecahydrobenzoꢀ

1,4,7,10,13,16ꢀhexaoxacyclooctadecinꢀ18ꢀyl)ꢀtꢀ3ꢀ(1ꢀisopropylꢀ

pyridiniumꢀ4ꢀyl)cyclobutyl]ꢀ1ꢀisopropylpyridinium diiodide (diꢀ

iodate) (A_1d, rctt isomer of the cyclobutane derivative from comꢀ

pound 1d, type A). ¹H NMR, δ: 1.505 and 1.512 (both d, 12 H,

2 Me₂CH, J = 6.4 Hz); 3.51 (s, 8 H, 4 CH₂O); 3.52—3.61

(m, 16 H, 8 CH₂O); 3.69 and 3.72 (both m, 4 H each,

4 CH₂CH₂OAr); 3.95 (m, 8 H, 4 CH₂OAr); 4.83 (dd, 2 H,

2 CHAr, J = 9.0 Hz, J = 8.2 Hz); 4.90 (sept, 2 H, 2 CHMe₂, J =

6.4 Hz); 4.93 (dd, 2 H, 2 CHPy, J = 9.0 Hz, J = 8.2 Hz); 6.75

(br.d, 2 H, 2 H(6´), J = 8.4 Hz); 6.77 (d, 2 H, 2 H(5´), J =

8.4 Hz); 6.80 (br.s, 2 H, 2 H(2´)); 7.92 (d, 4 H, 2 H(3), 2 H(5),

J = 6.3 Hz); 8.98 (d, 4 H, 2 H(2), 2 H(6), J = 6.3 Hz).

rꢀ4ꢀ[cꢀ2,tꢀ4ꢀDi(2,3,5,6,8,9,11,12,14,15ꢀdecahydrobenzoꢀ

1,4,7,10,13,16ꢀhexaoxacyclooctadecinꢀ18ꢀyl)ꢀtꢀ3ꢀ(1ꢀoctadecylꢀ

pyridiniumꢀ4ꢀyl)cyclobutyl]ꢀ1ꢀoctadecylpyridinium diperchlorate

(A_1e, rctt isomer of the cyclobutane derivative from compound 1e,

type A) was prepared as a yellowish powder, m.p. 127—128 °C.

Found (%): C, 63.16; H, 8.98; N, 1.98. C₈₂H₁₃₂Cl₂N₂O₂₀•H₂O.

Calculated (%): C, 63.34; H, 8.69; N, 1.80. ¹H NMR

(DMSOꢀd₆—CDCl₃(4 : 1)), δ: 0.85 (t, 6 H, 2 Me, J = 6.8 Hz);

1.23 (s, 60 H, 2 (CH₂)₁₅); 1.78 (m, 4 H, 2 CH₂CH₂N); 3.52 (s,

rꢀ4ꢀ[cꢀ2,tꢀ4ꢀBis(3,4ꢀdimethoxyphenyl)ꢀtꢀ3ꢀ(1ꢀethylpyridiꢀ

niumꢀ4ꢀyl)cyclobutyl]ꢀ1ꢀethylpyridinium diiodide (diiodate) (A_2a,

rctt isomer of the cyclobutane derivative from compound 2a,

1

type A). H NMR, δ: 1.42 (t, 6 H, 2 Me, J = 7.2 Hz); 3.66 and

3.68 (both s, 6 H each, 4 MeO); 4.50 (q, 4 H, 2 CH₂, J =

7.2 Hz); 4.82 (dd, 2 H, 2 CHAr, J = 10.5 Hz, J = 7.4 Hz); 4.91

(dd, 2 H, 2 CHPy, J = 10.5 Hz, J = 7.4 Hz); 6.78 (s, 4 H,

2 H(5´), 2 H(6´)); 6.82 (s, 2 H, 2 H(2´)); 7.97 (d, 4 H, 2 H(3),

2 H(5), J = 6.5 Hz); 8.89 (d, 4 H, 2 H(2), 2 H(6), J = 6.5 Hz).

rꢀ4ꢀ[cꢀ2,tꢀ4ꢀBis(3,4ꢀdimethoxyphenyl)ꢀtꢀ3ꢀ(1ꢀethylpyriꢀ

diniumꢀ4ꢀyl)cyclobutyl]ꢀ1ꢀethylpyridinium diperchlorate (A_3a

,

rctt isomer of the cyclobutane derivative from compound 3a,

type A) was prepared as a paleꢀyellow powder, m.p. 155—158 °C.

Found (%): C, 55.32; H, 5.37; N, 4.05. C₃₄H₄₀Cl₂N₂O₁₂. Calꢀ

1

culated (%): C, 55.22; H, 5.45; N, 3.79. H NMR, δ: 1.42 (t,

6 H, 2 Me, J = 7.3 Hz); 3.66 and 3.68 (both s, 6 H each,

4 MeO); 4.50 (q, 4 H, 2 CH₂, J = 7.3 Hz); 4.81 (dd, 2 H,

2 CHAr, J = 9.8 Hz, J = 7.5 Hz); 4.90 (dd, 2 H, 2 CHPy, J =

9.8 Hz, J = 7.5 Hz); 6.78 (s, 4 H, 2 H(5´), 2 H(6´)); 6.80 (s, 2 H,

2 H(2´)); 7.95 (d, 4 H, 2 H(3), 2 H(5), J = 6.7 Hz); 8.87 (d, 4 H,

2 H(2), 2 H(6), J = 6.7 Hz).

1ꢀEthylꢀrꢀ4ꢀ[tꢀ3ꢀ(1ꢀethylpyridiniumꢀ4ꢀyl)ꢀcꢀ2,tꢀ4ꢀdiphenylꢀ

cyclobutyl]pyridinium diperchlorate (A_3c, rctt isomer of the

cyclobutane derivative from compound 3c, type A) was prepared

as a colorless powder, m.p. 129—135 °C. Found (%): C, 57.99;

H, 5.15; N, 4.51. C₃₀H₃₂Cl₂N₂O₈. Calculated (%): C, 58.16;

1

H, 5.21; N, 4.52. H NMR, δ: 1.40 (t, 6 H, 2 Me, J = 7.2 Hz);

4.47 (q, 4 H, 2 CH₂, J = 7.2 Hz); 4.90 (dd, 2 H, 2 CHPh, J =

10.0 Hz, J = 7.2 Hz); 5.01 (dd, 2 H, 2 CHPy, J = 10.0 Hz, J =

7.2 Hz); 7.14 (t, 2 H, 2 H(4´), J = 7.3 Hz); 7.23 (t, 4 H, 2 H(3´),

2 H(5´), J = 7.8 Hz); 7.26 (d, 4 H, 2 H(2´), 2 H(6´), J = 7.5 Hz);

7.96 (d, 4 H, 2 H(3), 2 H(5), J = 6.7 Hz); 8.86 (d, 4 H, 2 H(2),

2 H(6), J = 6.7 Hz).

1ꢀEthylꢀrꢀ4ꢀ[tꢀ3ꢀ(1ꢀethylpyridiniumꢀ4ꢀyl)ꢀcꢀ2,tꢀ4ꢀbis(4ꢀ

methoxyphenyl)cyclobutyl]pyridinium diperchlorate (A_3d, rctt isoꢀ

mer of the cyclobutane derivative from compound 3d, type A)

was prepared as a paleꢀyellow powder, m.p. 110—113 °C.

Found (%): C, 56.39; H, 5.24; N, 4.31. C₃₂H₃₆Cl₂N₂O₁₀. Calꢀ

1

culated (%): C, 56.56; H, 5.34; N, 4.12. H NMR, δ: 1.41 (t,

1878

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

Vedernikov et al.

6 H, 2 Me, J = 7.3 Hz); 3.66 (s, 6 H, 2 MeO); 4.48 (q, 4 H,

2 CH₂, J = 7.3 Hz); 4.81 (dd, 2 H, 2 CHAr, J = 10.9 Hz, J =

7.5 Hz); 4.88 (dd, 2 H, 2 CHPy, J = 10.9 Hz, J = 7.5 Hz); 6.77

(d, 4 H, 2 H(3´), 2 H(5´), J = 9.0 Hz); 7.18 (d, 4 H, 2 H(2´),

2 H(6´), J = 9.0 Hz); 7.92 (d, 4 H, 2 H(3), 2 H(5), J = 6.9 Hz);

8.87 (d, 4 H, 2 H(2), 2 H(6), J = 6.9 Hz).

of the cyclobutane derivative from compound 3f, type A).

¹H NMR, δ: 1.42 (t, 6 H, 2 Me, J = 7.3 Hz); 4.51 (q, 4 H,

2 CH₂, J = 7.3 Hz); 4.96 (dd, 2 H, 2 CHAr, J = 9.2 Hz, J =

6.1 Hz); 5.01 (dd, 2 H, 2 CHPy, J = 9.2 Hz, J = 6.1 Hz); 7.24

(dd, 2 H, 2 H(6´), J = 8.5 Hz, J = 1.9 Hz); 7.49 (d, 2 H, 2 H(5´),

J = 8.5 Hz); 7.60 (d, 2 H, 2 H(2´), J = 1.9 Hz); 7.96 (d, 4 H,

2 H(3), 2 H(5), J = 7.1 Hz); 8.92 (d, 4 H, 2 H(2), 2 H(6),

J = 7.1 Hz).

1ꢀEthylꢀrꢀ4ꢀ{tꢀ3ꢀ(1ꢀethylpyridiniumꢀ4ꢀyl)ꢀcꢀ2,tꢀ4ꢀbis[4ꢀ

(methylsulfanyl)phenyl]cyclobutyl}pyridinium diperchlorate (A_3e,

rctt isomer of the cyclobutane derivative from compound 3e,

type A) was prepared as a paleꢀyellow powder, m.p. >169 °C

(with decomp.). Found (%): C, 51.35; H, 4.89; N, 4.06.

C₃₂H₃₆Cl₂N₂O₈S₂•2H₂O. Calculated (%): C, 51.40; H, 5.39;

rꢀ4ꢀ[tꢀ2,tꢀ3ꢀBis(3,4ꢀdichlorophenyl)ꢀcꢀ4ꢀ(1ꢀethylpyridiniumꢀ

4ꢀyl)cyclobutyl]ꢀ1ꢀethylpyridinium diperchlorate (B_3f, rctt isomer

of the cyclobutane derivative from compound 3f, type B).

¹H NMR, δ: 1.43 (t, 6 H, 2 Me, J = 7.3 Hz); 4.48 (q, 4 H,

1

3

N, 3.75. H NMR, δ: 1.42 (t, 6 H, 2 Me, J = 7.2 Hz); 2.39 (s,

2 CH₂, J = 7.3 Hz); 4.82 (m, 2 H, 2 CHAr, J_{transꢀH ,H}

=

b

a

3

6 H, 2 MeS); 4.49 (q, 4 H, 2 CH₂, J = 7.2 Hz); 4.85 (dd, 2 H,

2 CHAr, J = 9.8 Hz, J = 6.9 Hz); 4.93 (dd, 2 H, 2 CHPy, J =

9.8 Hz, J = 6.9 Hz); 7.11 (d, 4 H, 2 H(3´), 2 H(5´), J = 8.1 Hz);

7.20 (d, 4 H, 2 H(2´), 2 H(6´), J = 8.1 Hz); 7.94 (d, 4 H, 2 H(3),

2 H(5), J = 6.4 Hz); 8.88 (d, 4 H, 2 H(2), 2 H(6), J = 6.4 Hz).

rꢀ4ꢀ[cꢀ2,tꢀ4ꢀBis(3,4ꢀdichlorophenyl)ꢀtꢀ3ꢀ(1ꢀethylpyridiniumꢀ

4ꢀyl)cyclobutyl]ꢀ1ꢀethylpyridinium diperchlorate (A_3f, rctt isomer

6.7 Hz); 5.11 (m, 2 H, 2 CHPy, J_{transꢀH ,H}= 6.7 Hz); 7.20

a b

(dd, 2 H, 2 H(6´), J = 8.5 Hz, J = 1.9 Hz); 7.52 (d, 2 H, 2 H(5´),

J = 8.5 Hz); 7.57 (d, 2 H, 2 H(2´), J = 1.9 Hz); 7.98 (d, 4 H,

2 H(3), 2 H(5), J = 6.8 Hz); 8.90 (d, 4 H, 2 H(2), 2 H(6),

J = 6.8 Hz).

1ꢀEthylꢀrꢀ4ꢀ[tꢀ3ꢀ(1ꢀethylpyridiniumꢀ4ꢀyl)ꢀcꢀ2,tꢀ4ꢀbis(4ꢀ

nitrophenyl)cyclobutyl]pyridinium diperchlorate (A_3g, rctt isomer

Table 3. Crystallographic characteristics and the Xꢀray diffraction data collection and refinement statistics for the crystals

of 1b, 1b•C₆H₆•H₂O, 2a, and 2b•2C₆H₆

Compound

1b

1b•C₆H₆•H₂O

2a

2b•2C₆H₆

Molecular formula

M/g mol^–1

Crystal system

Space group

a/Å

b/Å

c/Å

α/deg

β/deg

C₂₅H₃₄INO₆

571.43

Monoclinic

P2₁

8.5838(12)

6.6948(9)

21.707(3)

90

92.289(4)

90

C₃₁H₄₂INO₇

667.56

Monoclinic

P2₁/n

10.0116(19)

8.0191(16)

38.651(8)

90

90.657(9)

90

C₁₇H₂₀INO₂

397.24

C₂₉H₃₃IN₂

536.47

Orthorhombic

P2₁2₁2₁

6.4685(3)

16.3121(9)

25.4514(14)

90

Triclinic

P^–1

8.1982(7)

9.5753(9)

12.1059(10)

69.928(3)

73.081(3)

71.771(3)

829.64(13)

2

90

γ/deg

V/Å³

1246.4(3)

2

1.523

3102.9(11)

4

2685.5(2)

4

1.327

Z

d_calc/g cm^–3

F(000)

1.429

1376

1.590

396

584

1096

µ(MoꢀKα)/mm^–1

Crystal dimensions/mm

θ Scan mode/range, deg

Ranges of indices

of measured

reflections

1.324

1.078

1.934

1.210

0.28×0.18×0.04

ω/2.59—29.00

–11 ≤ h ≤ 11,

–9 ≤ k ≤ 7,

–26 ≤ l ≤ 29

8603

0.30×0.14×0.10

ω/2.10—30.11

–13 ≤ h ≤ 12,

–11 ≤ k ≤ 11,

–54 ≤ l ≤ 52

19384

0.24×0.20×0.04

ω/1.83—29.00

–11 ≤ h ≤ 10,

–13 ≤ k ≤ 12,

–16 ≤ l ≤ 16

4677

0.48×0.22×0.10

ω/1.60—30.03

–7 ≤ h ≤ 9,

–22 ≤ k ≤ 16,

–33 ≤ l ≤ 34

15887

Number of measured

reflections

Number of independent

5811 (0.0354)

4953

8711 (0.1442)

3869

3923 (0.0157)

3604

6941 (0.0418)

6227

reflections (R_int

)

Number of reflections

with I > 2σ(I )

Number of variables

R factors based on

reflections with I > 2σ(I )

R factors based on

all reflections

298

368

270

305

R₁= 0.0508,

wR₂= 0.1008

R₁= 0.0645,

wR₂= 0.1052

1.030

R₁= 0.2277,

wR₂= 0.4949

R₁= 0.3052,

wR₂= 0.5214

1.070

R₁= 0.0226,

wR₂= 0.0586

R₁= 0.0253,

wR₂= 0.0597

1.073

R₁= 0.0688,

wR₂= 0.1596

R₁= 0.0779,

wR₂= 0.1640

1.166

Goodnessꢀofꢀfit on F ²

Residual electron

–0.841/1.938

–3.245/2.339

–0.611/0.554

–3.017/1.802

density (min/max)/e Å^–3

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1879

of the cyclobutane derivative from compound 3g, type A).

¹H NMR, δ: 1.41 (t, 6 H, 2 Me, J = 7.3 Hz); 4.47 (q, 4 H,

2 CH₂, J = 7.3 Hz); 5.13 (dd, 2 H, 2 CHAr, J = 8.8 Hz, J =

5.3 Hz); 5.18 (dd, 2 H, 2 CHPy, J = 8.8 Hz, J = 5.3 Hz); 7.57 (d,

4 H, 2 H(2´), 2 H(6´), J = 8.7 Hz); 7.99 (d, 4 H, 2 H(3), 2 H(5),

J = 6.7 Hz); 8.12 (d, 4 H, 2 H(3´), 2 H(5´), J = 8.7 Hz); 8.90 (d,

4 H, 2 H(2), 2 H(6), J = 6.7 Hz).

2 MeCH₂NMe₂, J = 6.9 Hz); 1.52 (t, 6 H, 2 MeCH₂N, J =

7.2 Hz); 3.52 (s, 12 H, 2 Me₂N); 3.90 (q, 4 H, 2 MeCH₂NMe₂,

J = 6.9 Hz); 4.58 (q, 4 H, 2 MeCH₂N, J = 7.2 Hz); 5.05 (dd,

2 H, 2 CHAr, J = 7.1 Hz, J = 4.5 Hz); 5.10 (dd, 2 H, 2 CHPy,

J = 7.1 Hz, J = 4.5 Hz); 7.50 (d, 4 H, 2 H(2´), 2 H(6´), J =

8.6 Hz); 7.70 (d, 4 H, 2 H(3´), 2 H(5´), J = 8.6 Hz); 7.95 (d,

4 H, 2 H(3), 2 H(5), J = 6.6 Hz); 8.89 (d, 4 H, 2 H(2), 2 H(6),

J = 6.6 Hz).

rꢀ4ꢀ[tꢀ2,tꢀ3ꢀBis{4ꢀ[ethyl(dimethyl)ammonio]phenyl}ꢀcꢀ4ꢀ

(1ꢀethylpyridiniumꢀ4ꢀyl)cyclobutyl]ꢀ1ꢀethylpyridinium tetraꢀ

perchlorate (B_3h, rctt isomer of the cyclobutane derivative

from compound 3h, type B). ¹H NMR, δ: 1.00 (t, 6 H,

2 MeCH₂NMe₂, J = 7.3 Hz); 1.51 (t, 6 H, 2 MeCH₂N, J =

7.2 Hz); 3.55 (s, 12 H, 2 Me₂N); 3.93 (q, 4 H, 2 MeCH₂NMe₂,

J = 7.3 Hz); 4.59 (q, 4 H, 2 MeCH₂N, J = 7.2 Hz); 4.92 (m,

1ꢀEthylꢀrꢀ4ꢀ[cꢀ2ꢀ(1ꢀethylpyridiniumꢀ4ꢀyl)ꢀtꢀ3,tꢀ4ꢀbis(4ꢀ

nitrophenyl)cyclobutyl]pyridinium diperchlorate (B_3g, rctt isomer

of the cyclobutane derivative from compound 3g, type B).

¹H NMR, δ: 1.44 (t, 6 H, 2 Me, J = 7.4 Hz); 4.50 (q, 4 H,

3

2 CH₂, J = 7.4 Hz); 5.07 (m, 2 H, 2 CHAr, J_{transꢀH ,H}

=

6.7 Hz); 5.21 (m, 2 H, 2 CHPy, J_{transꢀH ,H}_b= 6.7 Hz); 7.53^a(d,

b

3

a

4 H, 2 H(2´), 2 H(6´), J = 8.9 Hz); 8.04 (d, 4 H, 2 H(3), 2 H(5),

J = 6.7 Hz); 8.10 (d, 4 H, 2 H(3´), 2 H(5´), J = 8.9 Hz); 8.93 (d,

4 H, 2 H(2), 2 H(6), J = 6.7 Hz).

rꢀ4ꢀ[cꢀ2,tꢀ4ꢀBis{4ꢀ[ethyl(dimethyl)ammonio]phenyl}ꢀtꢀ3ꢀ

(1ꢀethylpyridiniumꢀ4ꢀyl)cyclobutyl]ꢀ1ꢀethylpyridinium tetraꢀ

perchlorate (A_3h, rctt isomer of the cyclobutane derivative

from compound 3h, type A). ¹H NMR, δ: 0.95 (t, 6 H,

3

2 H, 2 CHAr, J_{transꢀH ,H}= 6.5 Hz); 5.17 (m, 2 H, 2 CHPy,

³J_{transꢀH ,H}= 6.5 Hz); 7^a.55 (d, 4 H, 2 H(2´), 2 H(6´), J =

b

8.6 Hz)^a; 7.83 (d, 4 H, 2 H(3´), 2 H(5´), J = 8.6 Hz); 7.99 (d,

4 H, 2 H(3), 2 H(5), J = 6.5 Hz); 8.92 (d, 4 H, 2 H(2), 2 H(6),

J = 6.5 Hz).

b

Table 4. Crystallographic characteristics and the Xꢀray diffraction data collection and refinement statistics for the crystals

of 3a, 3b, 3b•2C₆H₆, and 3c•C₆H₆

Compound

3a

3b

3b•2C₆H₆

3c•C₆H₆

Molecular formula

M/g mol^–1

Crystal system

Space group

a/Å

b/Å

c/Å

α/deg

C₁₇H₂₀ClNO₆

369.79

Monoclinic

P2₁/c

6.9564(10)

21.202(3)

11.4501(16)

90

C₁₇H₂₁ClN₂O₄

352.81

Orthorhombic

P2₁2₁2₁

6.8668(2)

8.0649(3)

30.7437(9)

90

C₂₉H₃₃ClN₂O₄

509.02

Orthorhombic

P2₁2₁2₁

6.4752(4)

16.5448(11)

25.7090(16)

90

C₂₁H₂₂ClNO₄

387.85

Orthorhombic

Pbca

12.7358(15)

16.560(2)

18.182(2)

90

β/deg

91.514(6)

90

1688.2(4)

4

1.455

396

90

γ/deg

V/Å³

1702.59(9)

4

1.376

2754.2(3)

4

1.228

3834.6(8)

8

1.344

Z

d_calc/g cm^–3

F(000)

744

1080

1632

µ(MoꢀKα)/mm^–1

Crystal dimensions/mm

θ Scan mode/range, deg

Ranges of indices

of measured

reflections

0.261

0.248

0.174

0.226

0.36×0.26×0.14

ω/1.78—27.00

–8 ≤ h ≤ 8,

–27 ≤ k ≤ 26,

–14 ≤ l ≤ 14

11767

0.42×0.36×0.08

ω/2.61—28.99

–8 ≤ h ≤ 9,

–7 ≤ k ≤ 10,

–41 ≤ l ≤ 37

10955

0.40×0.14×0.10

ω/2.01—30.01

–8 ≤ h ≤ 9,

–19 ≤ k ≤ 23,

–35 ≤ l ≤ 33

18951

0.38×0.26×0.26

ω/2.24—30.53

–15 ≤ h ≤ 18,

–21 ≤ k ≤ 23,

–15 ≤ l ≤ 25

26879

Number of measured

reflections

Number of independent

3649 (0.0725)

2953

4386 (0.0350)

3739

7444 (0.1679)

3333

5855 (0.0723)

3026

reflections (R_int

)

Number of reflections

with I > 2σ(I )

Number of variables

R factors based on

reflections with I > 2σ(I )

R factors based on

all reflections

344

255

342

401

R₁= 0.1367,

wR₂= 0.3761

R₁= 0.1506,

wR₂= 0.3872

1.574

R₁= 0.0791,

wR₂= 0.2262

R₁= 0.0912,

wR₂= 0.2368

1.064

R₁= 0.1364,

wR₂= 0.2889

R₁= 0.2560,

wR₂= 0.3553

1.012

R₁= 0.1018,

wR₂= 0.2840

R₁= 0.1735,

wR₂= 0.3004

1.075

Goodnessꢀofꢀfit on F ²

Residual electron

–0.976/1.927

–0.462/0.948

–0.501/1.533

–0.695/0.408

density (min/max)/e Å^–3

1880

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

Vedernikov et al.

rꢀ4ꢀ[tꢀ2,tꢀ4ꢀBis{4ꢀ[ethyl(dimethyl)ammonio]phenyl}ꢀcꢀ3ꢀ

(1ꢀethylpyridiniumꢀ4ꢀyl)cyclobutyl]ꢀ1ꢀethylpyridinium tetraꢀ

perchlorate (C_3h, rtct isomer of the cyclobutane derivative

from compound 3h, type C). ¹H NMR, δ: 0.95 (t, 6 H,

2 MeCH₂NMe₂, J = 6.9 Hz); 1.52 (t, 6 H, 2 MeCH₂N, J =

7.2 Hz); 3.52 (s, 12 H, 2 Me₂N); 3.89 (q, 4 H, 2 MeCH₂NMe₂,

J = 6.9 Hz); 4.23 (t, 2 H, 2 CHAr, J = 9.7 Hz); 4.34 (t, 2 H,

2 CHPy, J = 9.7 Hz); 4.58 (q, 4 H, 2 MeCH₂N, J = 7.2 Hz);

7.71 (d, 4 H, 2 H(2´), 2 H(6´), J = 8.6 Hz); 7.84 (d, 4 H,

2 H(3´), 2 H(5´), J = 8.6 Hz); 8.24 (d, 4 H, 2 H(3), 2 H(5), J =

6.6 Hz); 9.06 (d, 4 H, 2 H(2), 2 H(6), J = 6.6 Hz).

8.7 Hz); 7.83 (d, 4 H, 2 H(3´), 2 H(5´), J = 8.7 Hz); 8.20 (d,

4 H, 2 H(3), 2 H(5), J = 6.5 Hz); 9.06 (d, 4 H, 2 H(2), 2 H(6),

J = 6.5 Hz).

rꢀ2ꢀ[cꢀ2,tꢀ4ꢀBis(3,4ꢀdimethoxyphenyl)ꢀtꢀ3ꢀ(3ꢀethylꢀ1,3ꢀ

benzothiazolꢀ3ꢀiumꢀ2ꢀyl)cyclobutyl]ꢀ3ꢀethylꢀ1,3ꢀbenzothiazolꢀ

3ꢀium diperchlorate (A₅, rctt isomer of the cyclobutane derivaꢀ

tive from compound 5, type A) was prepared as a yellow powder,

m.p. >192 °C (with decomp.). Found (%): C, 53.56; H, 4.68;

N, 3.44. C₃₈H₄₀Cl₂N₂O₁₂S₂. Calculated (%): C, 53.58; H, 4.73;

N, 3.29. ¹H NMR, δ: 1.34 (t, 6 H, 2 MeCH₂N, J = 7.1 Hz); 3.59

(s, 6 H, 2 3ꢀMeO); 3.66 (s, 6 H, 2 4ꢀMeO); 4.55 (m, 2 H,

2 MeCHH´N); 4.69 (m, 2 H, 2 MeCHH´N); 5.30 (dd, 2 H,

2 CHAr, J = 8.6 Hz, J = 7.9 Hz); 5.47 (dd, 2 H, 2 CHHet, J =

8.6 Hz, J = 7.9 Hz); 6.91 (d, 2 H, 2 H(5´), J = 8.4 Hz); 7.03 (d,

2 H, 2 H(2´), J = 1.9 Hz); 7.19 (dd, 2 H, 2 H(6´), J = 8.4 Hz,

J = 1.9 Hz); 7.82 (m, 2 H, 2 H(6)); 7.90 (m, 2 H, 2 H(5));

8.25 (d, 2 H, 2 H(4), J = 8.5 Hz); 8.48 (d, 2 H, 2 H(7),

J = 8.2 Hz).

rꢀ4ꢀ[tꢀ2,cꢀ3ꢀBis{4ꢀ[ethyl(dimethyl)ammonio]phenyl}ꢀtꢀ4ꢀ

(1ꢀethylpyridiniumꢀ4ꢀyl)cyclobutyl]ꢀ1ꢀethylpyridinium tetraꢀ

perchlorate (D_3h, rtct isomer of the cyclobutane derivative

from compound 3h, type D). ¹H NMR, δ: 0.76 (t, 6 H,

2 MeCH₂NMe₂, J = 7.0 Hz); 1.39 (t, 6 H, 2 MeCH₂N, J =

7.2 Hz); 3.46 (s, 12 H, 2 Me₂N); 3.82 (q, 4 H, 2 MeCH₂NMe₂,

J = 7.0 Hz); 4.23 (m, 2 H, 2 CHAr, ³J_{transꢀH ,H}_a= 10.0 Hz); 4.32

b

3

(m, 2 H, 2 CHPy, J_{transꢀH ,H}= 10.0 Hz); 4.47 (q, 4 H,

Xꢀray diffraction study. Crystals of dyes 1b, 2a,b, 3a—e,g,

and 5 were grown by slow diffusion of benzene vapor into their

a

b

2 MeCH₂N, J = 7.2 Hz); 7.68 (d, 4 H, 2 H(2´), 2 H(6´), J =

Table 5. Crystallographic characteristics and the Xꢀray diffraction data collection and refinement statistics for the crystals

of 3d, 3d•C₆H₆, 3e, and 3e•C₆H₆

Compound

3d

3d•C₆H₆

3e

3e•C₆H₆

Molecular formula

M/g mol^–1

Crystal system

Space group

a/Å

b/Å

c/Å

α/deg

C₁₆H₁₈ClNO₅

339.76

C₂₂H₂₄ClNO₅

417.87

C₁₆H₁₈ClNO₄S

355.82

C₂₂H₂₄ClNO₄S

433.93

Monoclinic

P2₁/n

7.5224(5)

11.3017(8)

18.8763(13)

90

P2₁/c

17.738(3)

6.5673(12)

18.083(3)

90

P2₁/n

7.9144(3)

11.1005(4)

19.0056(7)

90

P2₁/c

17.9283(7)

6.6644(3)

18.0521(6)

90

β/deg

91.2130(10)

90

1604.43(19)

4

99.680(7)

90

2076.6(6)

4

1.337

880

96.345(2)

90

1659.49(11)

4

101.031(2)

90

2117.04(14)

4

γ/deg

V/Å³

Z

d_calc/g cm^–3

F(000)

1.407

712

1.424

744

1.361

912

µ(MoꢀKα)/mm^–1

Crystal dimensions/mm

θ Scan mode/range, deg

Ranges of indices

of measured

reflections

0.263

0.217

0.375

0.308

0.44×0.24×0.16

ω/2.10—30.01

–10 ≤ h ≤ 10,

–7 ≤ k ≤ 15,

–26 ≤ l ≤ 21

10899

0.18×0.10×0.02

ω/2.29—29.00

–24 ≤ h ≤ 24,

–8 ≤ k ≤ 8,

–24 ≤ l ≤ 24

13926

0.36×0.18×0.14

ω/2.69—30.03

–10 ≤ h ≤ 11,

–15 ≤ k ≤ 13,

–26 ≤ l ≤ 26

15415

0.48×0.30×0.12

ω/3.27—30.51

–20 ≤ h ≤ 25,

–9 ≤ k ≤ 7,

–21 ≤ l ≤ 25

12632

Number of measured

reflections

Number of independent

4409 (0.0434)

2700

5458 (0.2621)

1536

4826 (0.0524)

2718

6244 (0.0255)

4838

reflections (R_int

)

Number of reflections

with I > 2σ(I )

Number of variables

R factors based on

reflections with I > 2σ(I )

R factors based on

all reflections

329

393

349

439

R₁= 0.0538,

wR₂= 0.0987

R₁= 0.1053,

wR₂= 0.1138

1.029

R₁= 0.0919,

wR₂= 0.1891

R₁= 0.2930,

wR₂= 0.2370

0.730

R₁= 0.0533,

wR₂= 0.1245

R₁= 0.1122,

wR₂= 0.1504

1.003

R₁= 0.0478,

wR₂= 0.1153

R₁= 0.0657,

wR₂= 0.1257

1.026

Goodnessꢀofꢀfit on F ²

Residual electron

–0.318/0.226

–0.519/0.496

–0.387/0.506

–0.329/0.586

density (min/max)/e Å^–3

Solidꢀstate photocycloaddition of styryl dyes

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

1881

acetonitrile solutions in the dark. Solventꢀfree crystals of dyes

3b—e were grown by saturating acetonitrile solutions with ethyl

acetate vapor. Crystals of dye 3f were grown by saturating a

solution in an acetonitrile—ethyl acetate mixture with hexane

vapor.

5•0.5MeCN•0.5H₂O, the hydrogen atoms were refined either

isotropically or using a riding model.

In most of the crystal structures, the dye cation is disordered

over two positions. The occupancy ratios for two s conformers

were 0.63 : 0.37 (2b•2C₆H₆), 0.50 : 0.50 (3b), 0.55 : 0.45

(3b•2C₆H₆), 0.53 : 0.47 (3c•C₆H₆), 0.74 : 0.26 (3d), 0.77 : 0.23

(3d•C₆H₆), 0.52 : 0.48 (3е), 0.91 : 0.09 (3e•C₆H₆), and

0.64 : 0.36 (3f). In some crystals, the perchlorate ion is

rotationally disordered over two positions (the rotation about

the center of gravity) with an occupancy ratio of 0.65 : 0.35 (3a),

0.93 : 0.07 (3d•C₆H₆), and 0.95 : 0.05 (3e•C₆H₆). In the other

crystals, the disorder of this anion is described as a spinning top

with an occupancy ratio of 0.71 : 0.29 (3f) and 0.68 : 0.32

(5•0.5MeCN•0.5H₂O). In the crystals of 3c•C₆H₆, the

benzene molecule is disordered over two close positions

with an occupancy ratio of 0.77 : 0.23. In the crystal of

5•0.5MeCN•0.5H₂O, the MeCN solvent molecules and two

water solvent molecules alternately occupy close positions with

an occupancy ratio of 0.50 : 0.25 : 0.25 (the H atoms of the water

molecules were not located).

Single crystals of the dyes, which were stored in the dark,

were mounted on a Bruker SMARTꢀCCD diffractometer in a

cold nitrogen stream (T = 120.0(2) K). The experimental Xꢀray

reflections were measured using MoꢀKα radiation (0.71073 Å,

graphite monochromator, ωꢀscanning technique). The Xꢀray

diffraction data were processed using the SAINT program.⁴⁷All

structures were solved by direct methods and refined by the fullꢀ

matrix leastꢀsquares method based on F ²with anisotropic disꢀ

placement parameters for nonhydrogen atoms. For the crystals

of 1b, 1b•C₆H₆•H₂O, 2a, and 2b•2C₆H₆, absorption correcꢀ

tions were applied using the SADABS method. The hydroꢀ

gen atoms were positioned geometrically and refined either

isotropically (2a and 3a,g) or using a riding model (1b,

1b•C₆H₆•H₂O, 2b•2C₆H₆, 3b, 3b•2C₆H₆, and 3c•C₆H₆).

In the structures of 3d, 3d•C₆H₆, 3е, 3e•C₆H₆, 3f, and

Table 6. Crystallographic characteristics and the Xꢀray diffraction data collection and refinement statistics for

the crystals of 3f,g and 5•0.5MeCN•0.5H₂O

Compound

3f

3g

5•0.5MeCN•0.5H₂O

Molecular formula

M/g mol^–1

Crystal system

Space group

a/Å

b/Å

c/Å

α/deg

β/deg

C₁₅H₁₄Cl₃NO₄

378.62

Monoclinic

P2₁/c

7.2511(6)

20.8503(16)

11.1782(8)

90

108.769(2)

90

C₁₅H₁₅ClN₂O₆

354.74

Monoclinic

P2₁/n

7.8098(5)

18.2263(13)

10.9959(8)

90

95.505(2)

90

C₂₀H_22.5ClN_1.5O_6.5

455.41

S

Triclinic

P^–1

7.4197(15)

11.398(2)

14.333(3)

108.40(3)

100.66(3)

92.56(3)

1123.3(4)

2

γ/deg

V/Å³

1600.1(2)

4

1.572

1557.98(19)

4

Z

d_calc/g cm^–3

F(000)

1.512

736

1.346

476

776

µ(MoꢀKα)/mm^–1

Crystal dimensions/mm

θ Scan mode/range, deg

Ranges of indices

of measured

reflections

0.591

0.281

0.302

0.16×0.08×0.08

ω/1.95—30.03

–7 ≤ h ≤ 9,

–28 ≤ k ≤ 17,

–15 ≤ l ≤ 15

10982

0.62×0.32×0.26

ω/2.17—29.00

–10 ≤ h ≤ 10,

–24 ≤ k ≤ 14,

–11 ≤ l ≤ 15

7380

0.56×0.22×0.08

ω/1.89—28.99

–10 ≤ h ≤ 10,

–8 ≤ k ≤ 15,

–17 ≤ l ≤ 16

5886

Number of measured

reflections

Number of independent

4364 (0.0549)

2793

3887 (0.0199)

3070

5226 (0.0189)

3548

reflections (R_int

)

Number of reflections

with I > 2σ(I )

Number of variables

R factors based on

reflections with I > 2σ(I )

R factors based on

all reflections

378

277

386

R₁= 0.0552,

wR₂= 0.0951

R₁= 0.1038,

wR₂= 0.1075

1.030

R₁= 0.0357,

wR₂= 0.0964

R₁= 0.0507,

wR₂= 0.1018

1.053

R₁= 0.0753,

wR₂= 0.2323

R₁= 0.1062,

wR₂= 0.2516

1.128

Goodnessꢀofꢀfit on F ²

Residual electron

–0.334/0.260

–0.356/0.361

–0.727/0.913

density (min/max)/e Å^–3

1882

Russ.Chem.Bull., Int.Ed., Vol. 56, No. 9, September, 2007

Vedernikov et al.

The crystals of 1b•C₆H₆•H₂O were of low quality, and the

quality became worse in the course of the Xꢀray data collection.

This is, apparently, associated with the fact that the autophotoꢀ

cycloaddition rather rapidly proceeded in these crystals under

the action of light, resulting in the gradual degradation of single

crystals. Nevertheless, we succeeded in performing the Xꢀray

diffraction experiment. Benzene and water solvent molecules

were located in difference electron density maps. The water

molecule occupies the cavity of the crown ether and forms hydroꢀ

gen bonds with the oxygen atoms of the macrocycle. In spite of a

low accuracy of the Xꢀray diffraction data, it is sufficient for the

discussion of the crystal packing of this compound.

All calculations were carried out with the use of the

SHELXTLꢀPlus program package.⁴⁸The crystallographic charꢀ

acteristics and the Xꢀray diffraction data collection and refineꢀ

ment statistics are given in Tables 3—6. The atomic coordinates

and other experimental data were deposited with the Cambridge

Structural Database;* the CSD refcodes 648503 (1b), 648504

(1b•C₆H₆•H₂O), 648505 (2a), 648506 (2b•2C₆H₆), 648507

(3a), 648508 (3b), 648509 (3b•2C₆H₆), 648510 (3c•C₆H₆),

648511 (3d), 648512 (3d•C₆H₆), 648513 (3e), 648514

(3e•C₆H₆), 648515 (3f), 648516 (3g), and 648517

(5•0.5MeCN•0.5H₂O).

11. F. H. Allen, M. F. Mahon, P. R. Raithby, G. P. Shields, and

H. A. Sparkes, New J. Chem., 2005, 29, 182.

12. Y. Ohashi, Acta Crystallogr., Sect. A, 1998, 54, 842.

13. H. Hosomi, S. Ohba, K. Tanaka, and F. Toda, J. Am. Chem.

Soc., 2000, 122, 1818.

14. I. TurowskaꢀTyrk, J. Phys. Org. Chem., 2004, 17, 837.

15. H. Nalanishi, W. Jones, J. M. Thomas, and K. Honda, Bull.

Chem. Soc. Jpn, 2002, 75, 2383.

16. S. P. Gromov and M. V. Alfimov, Izv. Akad. Nauk, Ser.

Khim., 1997, 641 [Russ. Chem. Bull., 1997, 46, 611 (Engl.

Transl.)].

17. S. P. Gromov, E. N. Ushakov, O. A. Fedorova, I. I. Baskin,

A. V. Buevich, E. N. Andryukhina, M. V. Alfimov,

D. Johnels, U. G. Edlund, J. K. Whitesell, and M. A. Fox,

J. Org. Chem., 2003, 68, 6115.

18. A. I. Vedernikov, N. A. Lobova, E. N. Ushakov, M. V.

Alfimov, and S. P. Gromov, Mendeleev Commun., 2005,

15, 173.

19. A. I. Vedernikov, S. K. Sazonov, P. S. Loginov, N. A.

Lobova, M. V. Alfimov, and S. P. Gromov, Mendeleev

Commun., 2007, 17, 29.

20. A. I. Vedernikov, S. P. Gromov, N. A. Lobova, L. G.

Kuz´mina, Yu. A. Strelenko, J. A. K. Howard, and M. V.

Alfimov, Izv. Akad. Nauk, Ser. Khim., 2005, 1896 [Russ.

Chem. Bull., Int. Ed., 2005, 54, 1954].

21. S. P. Gromov, A. I. Vedernikov, N. A. Lobova, L. G.

Kuz´mina, S. N. Dmitrieva, O. V. Tikhonova, and M. V.

Alfimov, Pat. RF 2278134; Byul. izobret. [Inventor Bull.],

2006, No. 17 (in Russian).

22. L. G. Kuz´mina, A. I. Vedernikov, N. A. Lobova, A. V.

Churakov, J. A. K. Howard, M. V. Alfimov, and S. P.

Gromov, New J. Chem., 2007, 31, 980.

23. L. G. Kuz´mina, A. I. Vedernikov, S. K. Sazonov, N. A.

Lobova, P. S. Loginov, J. A. K. Howard, M. V. Alfimov, and

S. P. Gromov, Kristallografiya, 2008, 53, № 2 [Crystallogr.

Repts, 2008, 53 (Engl. Transl.)].

The Xꢀray diffraction data for the crystals of 3с, 3с•0.5C₆H₆,

and 3h have been reported earlier²³and were deposited with the

Cambridge Structural Database (CSD refcodes 647441, 647442,

and 647445, respectively).

This study was financially supported by the Russian

Foundation for Basic Research (Project Nos 06ꢀ03ꢀ32434,

06ꢀ03ꢀ33162, and 06ꢀ03ꢀ08202ꢀofi), the Division of

Chemistry and Materials Science of the Russian Academy

of Sciences (Program No. 7), and the Royal Society of

Chemistry (Great Britain, Personal Grants for L. G.

Kuz´mina, A. V. Churakov, and J. A. K. Howard).

24. J. L. R. Williams, R. E. Adel, J. M. Carlson, G. A. Reynolds,

D. G. Borden, and J. A. Ford, J. Org. Chem., 1963,

28, 387.WW

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* CCDC, 12 Union Road, Cambridge CB21EZ, UK (fax:

(+44)1223 33 6033; eꢀmail: deposit@ccdc.cam.ac.uk). The data

can also be obtained from the authors.

Solidꢀstate photocycloaddition of styryl dyes

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in revised form July 25, 2007

Article Doi

Styryl dyes. Synthesis and study of the solid-state [2+2] autophotocycloaddition by NMR spectroscopy and X-ray diffraction

DOI: 10.1007/s11172-007-0289-4

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