OPE/OPV H-mers: Synthesis, electronic properties, and spectroscopic responses to binding with transition metal ions

Tetrahedron 67 (20 1 1 ) 125e143

Contents lists available at ScienceDirect

Tetrahedron

journal homepage: w ww.elsevier.com/locate/tet

OPE/OPV H-mers: synthesis, electronic properties, and spectroscopic responses

to binding with transition metal ions

*

Ningzhang Zhou, Li Wang, David W. Thompson, Yuming Zhao

Department of Chemistry, Memorial University of Newfoundland, St. John’s, Newfoundland, Canada A1B 3X7

a r t i c l e i n f o

a b s t r a c t

Article history:

Received 25 August 2010

Received in revised form 1 November 2010

Accepted 2 November 2010

Available online 5 November 2010

A new type of structurally deﬁned H-shaped OPE/OPV co-oligomers (termed H-mers) functionalized

with various donor and/or acceptor end groups was synthesized by iterative Sonogashira coupling and

HornereWadswortheEmmons (HWE) reactions. Electronic substitution effects on the H-mer backbone

were investigated by UVevis absorption and ﬂuorescence spectroscopy. Some H-mers were found to

show spectral responses upon binding to an acid (TFA) or transition metal ions, revealing the applica-

bility of H-mers in the ﬁeld of chromophore and ﬂuorophore based chemosensors.

Keywords:

Oligomer

Electronic substitution

Sonogashira coupling

HWE reaction

Chemosensor

1. Introduction

of functional organic chromo-/ﬂuorophores to attain remarkable

molecular sensor performance.^46e52

The extensive studies on monodisperse and structurally deﬁned

-conjugated oligomers over the past few decades have not only

allowed the complex structureeproperty relationships for related

polymeric materials to be well understood, but also led to an

enormous array of oligomer and polymer-based materials useful for

advanced molecular electronic and optoelectronic applications.^1e9

Three basic structural themes can be generalized from the

numerous 2-dimensional conjugated oligomers so far reported in

the literature according to their molecular shapes; X, Y, and H-

shaped assemblages (henceforth referred to as X-mers, Y-mers, and

H-mers, respectively). Fig. 1 lists the representative core structures

of some 2-dimensional conjugated phenylene-based oligomer

scaffolds. A large number of oligomers derived from the backbones

of X-mers (also known as cruciforms)^19,39,53e62and Y-mers

(sometimes termed star-shaped oligomers)^{25,26,36,42,44,63e84}has

been synthesized and characterized in recent studies. In contrast,

the number of H-mers existing in the literature still remains rela-

tively small mainly because of their demanding and tedious

synthesis.^{31,36,37,59,85e87}

p

While the straightforward linearly

remains a popular design motif in the current

ily,^7,10e12a surging interest in constructing oligomers with various

p

-conjugated architecture still

p

-oligomer fam-

2-dimensional noncyclic p-frameworks has become notable in re-

cent years.^13e17A major rationale for pursuing such complex

structures lies in the opportunities of obtaining some unique

physical and electronic properties unattainable from linearly con-

jugated oligomers. For instance, the steric bulkiness of dendritic

Structurally, the distinction between H-mers and other 2-di-

mensional oligomers (X-mers and Y-mers) is that the pivotal seg-

ment of an H-mer is made up of a linear oligomeric moiety instead

of a monomeric unit, such as a single atom, arene or vinyl group,

etc. As such, the H-mers are predicted to show combined properties

and branched

solubility (processability) and optimizing

better optoelectronic and semi-conducting properties.^18e26The

relatively rigid molecular structures of 2-dimensional -oligomers

p-oligomers has been proven effective at improving

pep

aggregation for

p

serve nanoscale scaffolds for the construction of well-deﬁned

molecular optoelectronic and mechanical devices.^23,27e45The spa-

tially non-overlapping frontier molecular orbitals (FMOs) of 2-di-

stemming from conjugated and cross-conjugated

localization patterns as well as unique inter-oligomer

p

-electron de-

pep

in-

teractions. Moreover, the H-shaped topology allows more ﬂexibly

terminal functionalization on the oligomer framework such that

better control over electronic and physical properties can be exer-

ted at the molecular level. Such features should in turn render the

H-mer an appealing platform for the design of new oligomer and

polymer functional nanomaterials.^{9,36,59,85e87}In light of the paucity

mensional cruciform-shaped p-oligomers have enabled the design

* Corresponding author. Tel.: þ1 709 864 8747; fax: þ1 709 864 3702; e-mail

address: yuming@mun.ca (Y. Zhao).

doi:10.1016/j.tet.2010.11.012

126

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

Scheme 1. Synthesis of OPV precursor 14.

bromo-2-iodobenzaldehyde (12) in a nearly quantitative yield.

Compound 12 was subjected to a HornereWadswortheEmmons

(HWE) reaction with the phosphonate ylide generated by treating

bis(phosphonate) 13 with NaH, affording the desired dibromo-

diiodo-OPV precursor 14 in a reasonable yield of 45%.

OPV precursor 14 was subjected to Sonogashira coupling with

excess trimethylsilylacetylene (TMSA) catalyzed by Pd(PPh₃)₂Cl₂

and CuI in the presence of Et₃N as base to afford tetraalkynyl OPV

15 (Scheme 2). Removal of the TMS groups in compound 15 by

K₂CO₃at rt resulted in free terminal alkyne 16 in a quantitative

yield. Compound 16 then underwent a four-fold Sonogashira cou-

pling with iodobenzene to yield unsubstituted short H-mer 17 in

67% yield. In a similar manner, two D/A/substituted short H-mers,

18 and 19, were synthesized via the Sonogashira coupling ap-

proach. In these two H-mers, the terminal phenyl rings were, re-

spectively, functionalized with electron-donating eNMe₂and

electron-withdrawing eCOOMe groups to serve as models for

Fig. 1. Representative core structures for phenylene-based X-mers, Y-mers, and

H-mers.

of synthetic examples and fundamental understanding of H-mers

in the current literature, we recently set out a systematic survey on

a class of H-mers that hybridize linear oligo(phenylene ethynylene)

(OPE) and oligo(phenylene vinylene) (OPV) motifs as shown in

structure 6 (Fig. 1). In a preceding report, we have explored the

donor/acceptor (D/A) substitution effects on the UVevis absorption

and ﬂuorescence properties of some OPE/OPV H-mers and dem-

onstrated that upon functionalization with amino groups at the

terminal positions, the H-mer could give rise to efﬁcient ﬂuores-

cence sensing function towards acids and transition metal ions.⁸⁵

This article outlines our detailed studies on this type of H-mers in

a broader context, including efﬁcient synthetic methods, structur-

eeproperty relationship, electronic substitution effects, UVevis,

and ﬂuorescence spectroscopic responses to acid and various metal

cations.

probing the D/A-substitution effects on the

of short H-mers.

p-electronic properties

It is worth noting that the Sonogashira (alkynyl coupling) ap-

proach as demonstrated in Scheme 2 turned out to be very efﬁcient

in constructing D/A-substituted short OPE/OPV H-mers. On the

other hand, the synthetic strategy involving oleﬁnation at the last

stage of the H-mer backbone assemblage is also conceivably plau-

sible. To explore the effectiveness of this alternative synthetic route,

the synthesis of functionalized H-mer 18 was attempted via an

oleﬁnation reaction between phosphonate 13 and OPE-aldehyde 22

in the presence of base (Scheme 3). Unfortunately, despite nu-

merous conditions tried out (with different bases and solvents), the

HWE reaction did not afford the desirable H-mer product in

meaningful yield. In most cases, the reaction ended with either

signiﬁcant decomposition of the OPE-aldehyde precursor or

a mixture of multiple intractable side products. These ﬁndings thus

suggest that the HWE reaction is not suited to be placed at the ﬁnal

step in planning the synthesis of short OPE/OPV H-mers.

2. Synthesis of OPE/OPV H-mers

2.1. Synthesis of short OPE/OPV H-mers

To construct OPE/OPV H-mers, an OPV building block 14 had to be

acquired beforehand as the central pivotal bridge. As shown in

Scheme 1, 2-aminobenzoic acid (7) was brominated with Br₂to give

2-amino-5-bromobenzoic acid (8). Compound 8 underwent a di-

azotization reaction followed by treatment with KI to afford 5-

bromo-2-iodobenzoic acid(9), whichwas thensubjected toa Fischer

esteriﬁcation with MeOH in the presence of concd H₂SO₄to yield

methyl benzoate 10. Compound 10 was further reduced into benzyl

alcohol 11 by diisobutylaluminum hydride (DIBAL). Oxidation of 11

with pyridinium dichromate (PDC) resulted in the formation of 5-

To evaluate the electron ‘pushepull’ effect,⁷a D/A-substituted

H-mer OPE/OPV 29 (Scheme 4) was targeted (note that D/A herein

refersto‘donorandacceptor’, whileD/Adenotes ‘donororacceptor’).

In terms of synthetic efﬁciency, the convergent strategy of merging

two pre-assembled D/A-substituted OPE precursors by HWE re-

action was deemed concise and preferable for this type of H-mers,

although the HWE reaction failed in obtaining A-substituted H-mer

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

127

Scheme 2. Synthesis of short OPE/OPV H-mers 17e19 by Sonogashira coupling.

18 previously. As depicted in Scheme 4, the iodo group of compound

12 was ﬁrst converted into an alkynyl group by reacting with

1 M equiv of triisopropylsilylacetylene (TIPSA) under Sonogashira

conditions to give 23 in 94% yield. Another step of Sonogashira

coupling between 23 and TMSA afforded 24 in a high yield. Selective

removal of the TMS group in 24 with K₂CO₃led to compound 25,

which was then cross-coupled with methyl 2-iodobenzoate to yield

phenylacetylene dimer 26. Desilylation of 26 with tetrabuty-

lammonium ﬂuoride (TBAF) followed bycross coupling with 4-iodo-

N,N-dimethylaniline afforded OPE precursor 28 in a moderate yield

of 47%. At this juncture, it would only require one more step of HWE

reaction to accomplish the construction of D/A functionalized H-mer

29. Nevertheless, problematic outcomes of the HWE reaction similar

to those encountered in Scheme 3 emerged and hence forced us to

abandon this synthetic route.

Alternatively, the synthesis of D/A-substituted H-mer 29 by

a relatively lengthier iterative Sonogashira coupling route was in-

vestigated. As shown in Scheme 5, phosphonate 13 was ﬁrst depro-

tonated by NaH in THF to generate a ylide intermediate, which was

immediately reacted with aldehyde 23 to form OPV 30 in 45% yield

over two steps. Compound 30 was cross-coupled with 2 M equiv of

TMSA under Sonogashira conditions to afford tetraalkynylated OPV

31. Selective deprotection of the TMS groups in 31 by K₂CO₃then

yielded free terminal alkyne 32. Cross coupling of 32 with methyl

Scheme 3. Attempted synthesis of short OPE/OPV H-mer 18 by HWE reaction.

128

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

Scheme 4. Attempted synthesis of D/A substituted short OPE/OPV H-mer 29 by HWE reaction.

2-iodobenzoate under the catalysis of Pd/Cu gave oligomer 33 in

a decent yield. Finally, desilylation of 33 with TBAF, followed by cross

coupling with 4-iodo-N,N-dimethylaniline, successfully led to the

formation of D/A-substituted short H-mer 29. It should be noted that

in the last cross-coupling step involving 4-iodo-N,N-dimethylaniline

and terminal alkynes, the use of piperidine as base resulted in a much

higher yield than the commonly used base Et₃N.

a similar synthetic route, methoxy end-substituted dimer 46 was

acquired from 4-iodoanisole (42) through four synthetic steps as

outlined in Scheme 7.

With precursors 41 and 46 in hand, two D/A-substituted long

OPE/OPV H-mers, 47 and 48 were synthesized in reasonable yields

by a four-fold Sonogashira coupling reaction as illustrated in

Scheme 8. In a similar manner, an aldehyde end-substituted phe-

nylacetylene dimer 49 was cross-coupled with OPV precursor 14 to

afford another A-substituted long H-mer 50 in 68% yield. Note that

the yields of these coupling reactions were comparatively greater

than that of H-mer 36 (Scheme 6). This can be attributed to the

presence of D/A end groups in the phenylene ethynylene branches,

which activate the reactivity of terminal alkyne.

2.2. Synthesis of long OPE/OPV H-mers

At this point, short H-mers with various types of end groups

have been obtained. To investigate the effect of

p-conjugation

length on related molecular properties, a set of H-mers with rela-

tively longer OPE branches was subsequently targeted. The syn-

thesis of unsubstituted long OPE/OPV H-mer was readily achieved

by a four-fold Sonogashira coupling between iodoarene 35 and OPV

precursor 16 as shown in Scheme 6. The relatively low yield of this

reaction (36%) compared with previous cross coupling reactions

was ascribed to the occurrence of some undesirable homocoupling

side-reactions as well as mechanical loss during column chro-

matographic separation due to the high viscosity of the compound.

To synthesize D/A-substituted long OPE/OPV H-mers, the

strategy of employing Sonogashira coupling to construct the H-mer

skeleton at the ﬁnal stage of synthesis was planned and in-

vestigated. Two phenylacetylene dimers 41 and 46, end-substituted

with a donor (OMe) or acceptor (CN) group in each, were ﬁrst

prepared as shown in Scheme 7. A commercially available benzene

derivative, 4-bromobenzonitrile (37), was converted into 38 via

Sonogashira coupling with TMSA. Desilylation of 38 with K₂CO₃

followed by another Sonogashira coupling with iodoarene 35 gave

compound 40, which was readily desilylated with K₂CO₃to afford

cyano-substituted phenylacetylene dimer 41 in a good yield. By

In contrast to the attempted synthesis of short H-mer 29

(Scheme 4), the synthesis of D/A-substituted long OPE/OPV H-mers

by a convergent HWE strategy met with success. This synthetic

route began with the preparation of two D/A-substituted phenyl-

acetylene pentamers 52 and 54 via iterative Sonogashira reactions

(Scheme 9). Note that the two OPE precursors are regio-isomers to

one another (vide infra), resulting from different coupling se-

quences. The central phenyl ring of 52 and 54 was functionalized

with an aldehyde group to enable the assembly of respective

H-mers 55 and 56 via an HWE reaction with the phosphonate ylide

of 13 (Scheme 10) in satisfactory yields.

Finally, the synthesis of another D/A-substituted long OPE/OPV

H-mer 58 was carried out via a convergent Sonogashira coupling

approach outlined in Scheme 11. In this route, the iodo groups

of OPV precursor 14 were ﬁrst selectively cross-coupled

with 2 M equiv of phenylacetylene dimer 46 to yield a Z-shaped

OPE/OPV co-oligomer 57 in a reasonable yield. Another iteration of

two-fold Sonogashira coupling between 57 and phenylacetylene

dimer 49 thus gave D/A-substituted long H-mer 58 in 61% yield.

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

129

Scheme 5. Synthesis of D/A substituted short OPE/OPV H-mer 29 by Sonogashira coupling.

Scheme 6. Synthesis of long OPE/OPV H-mer 36 by Sonogashira coupling.

3. Nomenclature of substituted H-mers

Such an arrangement imparts the H-mer rather complex conjuga-

tion and cross-conjugation patterns. Of note is that the longest

linear conjugation path in the H-mer consists of the OPV unit and

two ortho-OPE segments (highlighted in pink color in the structures

shown in Fig. 2). The unsubstituted H-mer is achiral itself; however,

In the basic unsubstituted H-mer backbone, the central OPV

segment joints two parallel OPE branches in a skewed manner that

renders the molecule an italicized H-shape with a C₂symmetry.

Scheme 7. Synthesis of D/A-substituted phenylacetylene dimers 41 and 46.

130

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

Scheme 8. Synthesis of D/A-substituted long OPE/OPV H-mers 47, 48, and 50 by Sonogashira coupling.

it provides a stereogenic element to give rise to stereoisomers in

the cases that its termini are functionalized with different groups.

To facility the following discussions on the structures and proper-

ties of diverse substituted H-mers, a simple naming rule is devised

and illustrated in Fig. 2.

electron-accepting CN groups, whereas in compound 56 the longest

conjugation path is ended with electron-donating OMe groups.

4. Electronic substitution effects on the steady-state

electronic spectroscopic properties of H-mers

Depending on the length of the OPE branches, the H-mers are

generally categorized as SH (short H-mers) and LH (long H-mers).

The positions of terminal functionality attached to the H-mer back-

bone are designated by numbers shown in Fig. 2. In this way, the

substituted H-mers can be unambiguously named. For example,

short D/A substituted H-mer 29 is given a short name: SH-

1,3-(COOMe)₂-2,4-(NMe₂)₂. Also, from a short name, the exact

structure and substitution pattern of each H-mer derivative can be

easily perceived. Inparticular, the structural differences between the

two stereoisomers, 55 (LH-1,3-(CN)₂-2,4-(OMe)₂) and 56 (LH-2,4-

(CN)₂-1,3-(OMe)₂), can be clearly noted from their short names. As

the 1,3-terminal positions are in direct conjugation and the 2,4-ter-

minal positions are in cross-conjugation, the electronic substitution

effects experienced by the two isomers are in theory different; in

compound 55, the longest conjugation path is endcapped with

The electronic properties of the H-mers in the ground and ex-

cited states have been investigated by UVevis absorption and

ﬂuorescence spectroscopy. Detailed electronic spectra are given in

Fig. 3 and spectroscopic data are summarized in Table 1.

All the compounds have similar patterns of electronic transi-

tions; however, the band intensities vary as a function of the sub-

stituent pattern. These spectral features are clearly illustrated in

Fig. 3A. The unsubstituted short H-mer 17 (SH) shows a broad un-

structured

p/p transition band with l_maxat 327 and 386 nm,

*

along with a low-energy tail at ca. 410 nm. When the terminal

positions of the short H-mer are substituted with D/A or D-A

groups, the absorption spectral envelopes are red-shifted as a re-

sponse to changes in the electronic wavefunctions, which arise

from alterations of the orbital energies. D-substitution (in the case

Scheme 9. Synthesis of D/A-substituted phenylacetylene pentamers 52 and 54 by Sonogashira coupling.

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

131

Scheme 10. Synthesis of D/A-substituted long OPE/OPV H-mers 55 and 56 by HWE reaction.

of 19, SH-(NMe₂)₄) gives rise to the most notable red shift of the

lowest-energy absorption band, while A-substitution (in the case of

18, SH-(COOMe)₄) affords a very small red shift. When the terminal

positions of the short H-mer backbone are functionalized with two

donor and two acceptor groups (in the case of 29, SH-1,3-

(COOMe)₂-2,4-(NMe₂)₂), the small change in the energy of the

maxima of the spectral envelope (l_max) is likely due to offsetting

electronic substituent effects as evidenced by the nearly superim-

posable 410 nm transition with that of the 19 (SH-(NMe₂)₄).

The emission spectra of short H-mers are shown in Fig. 3B. SH 17

shows distinct vibronic progression at 425, 450, and 480(sh) nmwith

a vibronic spacing of 1310 cm^ꢀ1consistent with a C]C accepting

mode. The vibronic features are still retained in the case of acceptor

substitution (18, SH-(COOMe)₄), whereas in the cases of D- and D-A

substitution (19 and 29) the emission spectra show broad and fea-

tureless bands, which are signiﬁcantly shifted to lower energy (lon-

ger wavelength). The energetic trends found in the absorption data

mirror those observed in the emission spectra presumably due to the

similar vibrational and solvent reorganization energetics for analo-

gous H-mers as manifested by their relatively constant Stokes shifts

(Table 1).

Long unsubstituted H-mer 36 (LH) shows two resolved ab-

sorption bands at 324 and 376 nm (Fig. 3C). Upon substitution with

A (47 LH-(CN)₄) or D (47 LH-(OMe)₄) groups, only a very small red

shift is observed. Unlike the short H-mer series, D- or A-sub-

stitution does not result in any transitions readily assigned to

a charge transfer transition. In the context of the discussion below,

charge transfer bands are those transitions where an electron has

been removed from a donor group to an acceptor group. It is in-

teresting to note that the spectral features of the two D-A

substituted LH isomers 55 and 56 are different. Compound 55

(LH-1,3-(CN)₂-2,4-(OMe)₂) has two A groups terminated at the ends

of the longest conjugation path. The constitutional isomer 56

(LH-2,4-(CN)₂-1,3-(OMe)₂) has two D groups attached to the ter-

mini of the longest conjugation path as well. UVevis absorption

bands of 55 and 56 appear at similar wavelengths without any

signiﬁcant shifts. However, their molar absorptivities are dramati-

cally different; in the low-energy region, the extinction coefﬁcients

of 55 are approximately doubled as those of 56. These observations

suggest that the intensities are due to the statistical effects. In this

interpretation the chromophores are electronically uncoupled and

do not interact with each other. Therefore, the intensities of the

Scheme 11. Synthesis of D/A-substituted long OPE/OPV H-mer 58 by Sonogashira coupling.

132

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

1,2- and 5,6-substituent patterns result in signiﬁcant reduction of

the electronic communication between the terminal electronic

substituents attached to the long H-mer backbone. The mechanism

for the interaction of the substituents through the long H-mer

backbone appears to be subtle and awaits further investigations to

clearly elucidate.

5. Spectroscopic responses of H-mers in binding with TFA and

transition metal ions

The synthesized H-mers contain p-electron rich backbones and

substituents, which may interact covalently with added acids or

transition metal ions. Therefore, Lewis acid and base interactions

between the added analytes and H-mers should lead to signiﬁcant

changes in conformation and electronic nature. In principle, the

H-mer would display spectral responses to certain chemical spe-

cies, which forms the basis for chemical sensors. The response of

absorption/ﬂuorescence provides a powerful and sensitive reporter

for functional colorimetric molecular sensors. Described below are

the results of experiments where analytes, such as metal ions and

proton were added to H-mers to screen for potential highly selec-

tive chemosensors. A series of titrations were undertaken to ex-

plore the Lewis acid and base chemistry for H-mers with various

chemicals, including a strong organic acidetriﬂuoroacetic acid

(TFA), and ﬁve selected metal triﬂate saltseAgOTf, Cu(OTf)₂, Zn

(OTf)₂, Ba(OTf)₂, and Mg(OTf)₂.

Fig. 2. Nomenclature of substituted H-mers.

The addition of selected analytes to solutions of H-mers results

in different absorption and emission spectral responses. Table 2

summarizes the spectroscopic properties of the H-mer adducts

that are formed over the course of titrations. For the short H-mers,

two oligomers 19 and 29 carrying NMe₂as the end group show

signiﬁcant spectroscopic changes as a function of concentration of

TFA and two transition metal ions Ag^þand Cu^2þ(Figs. 4 and 5,

respectively).

The titration of H-mer 19 (SH-(NMe₂)₄) with TFA (Fig. 4A) results

in attenuation of the low-energy absorption band at 367 nm, with

concomitant growth of a new band at 329 nm. The spectral changes

are associated with the protonation of the four NMe₂groups by

TFA, which alters the nature of the NMe₂from electron-donating to

transitions are linear combination of independent chromophores on

the same molecules. These trends are clearly illustrated in Fig. 3C.

The ﬂuorescence spectrum of LH 36 shows characteristic

vibronic progression at 439 and 465 nm with a spacing (1275 cm^ꢀ1

)

similar to that of SH 17. Upon D/A substitution, the emission bands

show red shifts by 13e15 nm relative to 36 (Fig. 3D) with their

lineshapes slightly broadened. In comparison with the short

H-mers, electronic substitution effects on both the absorption and

emission spectra of long H-mers are signiﬁcantly reduced with the

extension of the conjugation length of the OPE branch. Apparently,

the effective conjugation paths have been attenuated due to

the presence of multi-substituents on the long OPE branches. The

Fig. 3. (A) UVevis spectra of short H-mers. (B) Fluorescence spectra of short H-mers. (C) UVevis spectra of long H-mers. (D) Fluorescence spectra of long H-mers.

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

133

Table 1

Summary of photophysical data for H-mers measured in deoxygenated CHCl₃at rt

Entry

Absorption

(nm)

Emission

(nm)

Stokes shift (cm^ꢀ1

)

l

e

(10⁴M^ꢀ1cm^ꢀ1

)

l

F

s (ns)

17

327

386

9.9

3.8

425

450

480(sh)

442

462

0.49

1.2

1.3

2360

6370

18

303(sh)

345

415(sh)

295

367

305(sh)

358

324

376

322

397

325

368

326

391

323

393

7.6

17

3.3

0.48

1.4

7.4

0.36

2.0

6.4

5.3

19

29

36

47

48

55

56

506

500

0.43

0.56

0.54

0.72

0.52

0.70

0.62

7910

8330

3810

2990

3710

3380

3080

14

0.29

0.46

6.7

11

6.5

11

1.9

3.2

1.0

1.6

439

465

450

480(sh)

450

479(sh)

450

480(sh)

451

2.0

2.2

1.3

1.6

1.8

1.3

1.4

1.5

1.6

488(sh)

a similar blue shift with the increasing concentration of TFA

(Fig. 4B). The low-energy emission at 506 nm is considerably at-

tenuated, with appearance of a structured emission spectrum

having bands at 431, 452, and 485 nm (sh). The spectral shape after

complete protonation by TFA (ca. 12,000 M equiv) is very similar to

the emission spectra of 17 (SH) and 18 (SH-(COOMe)₄).

Table 2

Summary of sensing effectiveness of H-mers towards TFA various metal triﬂate salts

Entry

TFA

Ag^þ

Cu^2þ

Zn^2þ

Ba^2þ

Mg^2þ

17

18

19

29

36

47

48

55

56

ꢀ

þ

ꢀ

þ

ꢀ

þ

ꢀ

Titration of 19 with Ag^þgives rise to similar absorption and

ﬂuorescence spectral changes to those observed for the TFA titra-

tion (Fig. 3C and D). The end point of Ag^þtitration requires only

14 M equiv, signiﬁcantly less than that observed for TFA titration

(ca. 12,000 M equiv). The large difference in the equilibrium

constants for Ag^þversus TFA is consistent with the hard and soft

acid/base (HSAB) theory, where the binding afﬁnity between the

NMe₂group and the soft Lewis acid Ag^þis expected to be much

larger than that of protonation.

ꢀ

Note that ‘þ’ denotes signiﬁcant absorption and ﬂuorescence spectral changes ob-

served in titration, ‘ꢀ’ signiﬁes no detectable spectral changes during titration.

electron-accepting [NHMe₂]^þ. Overall, the absorption spectrum of

19 shows a dramatic blue shift in binding with TFA. The ﬁnal

spectrum after saturation with TFA is quantitatively similar to the

absorption spectrum of unsubstituted short H-mer 17 (SH) as

shown in Fig. 3A. The ﬂuorescence spectrum of 19 also exhibits

Upon titration of 19 with TFA and Ag^þ(Fig. 4AeD), the shift of

isosbestic points is observed, suggesting the involvement of multi-

step processes in the reaction mechanism. Based on the global

spectral ﬁtting analysis (Table 3), a two-step binding mechanism is

Fig. 4. UVevis spectroscopic titrations of H-mer 19 (9.1 mM in CHCl₃) with (A) TFA, (C) AgOTf, and (E) Cu(OTf)₂. Fluorescence spectroscopic titrations of H-mer 19 (9.1 mM in CHCl₃)

with (B) TFA, (D) AgOTf, and (F) Cu(OTf)₂.

134

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

Fig. 5. UVevis spectroscopic titrations of H-mer 29 (6.0

mM in CHCl₃) with (A) TFA, (C) AgOTf, and (E) Cu(OTf)₂. Fluorescence spectroscopic titrations of H-mer 29 (6.0 mM in CHCl₃)

with (B) TFA (D) AgOTf, and (F) Cu(OTf)₂.

Table 3

Equilibrium constants for the binding of H-mers 19 and 29 to various chemical species in the ground and excited states

H-mer

Titrant

Ground state

Excited state

log K₁(M^ꢀ1

)

log K₁K₂(M^ꢀ2

)

log K₁(M^ꢀ1

)

log K₁K₂(M^ꢀ2

)

19

TFA

AgOTf

Cu(OTf)₂

3.5ꢁ0.030

9.6ꢁ0.28

5.7ꢁ0.015

18.8ꢁ0.28

22.2ꢁ0.29

3.6ꢁ0.037

10.6ꢁ0.53

13.4ꢁ0.74

6.4ꢁ0.045

19.4ꢁ0.50

22.8ꢁ0.74

10.4ꢁ0.030

29

TFA

AgOTf

Cu(OTf)₂

3.4ꢁ0.063

9.1ꢁ0.046

9.4ꢁ0.11

2.7ꢁ0.058

8.8ꢁ0.088

8.9ꢁ0.80

proposed as illustrated in Scheme 12. The two NMe₂groups located

at the 1,3-positions are supposed to be protonated or coordinate

with Ag^þin the ﬁrst step, while protonation or coordination at the

2,4-positions occurs in the second step (see Eq.1 and 2, Scheme 12).

In comparison with TFA and Ag^þtitrations, the titration of 19

with Cu^2þyields a decrease of the intensity of ICT absorption band,

but there is no shift for l_max(Fig. 4E). Also, with the titration, the ICT

band broadens resulting in a systematic increase in the UVevis

baseline and becomes more prominent as the saturation limit is

reached. A similar effect is observed in the ﬂuorescence spectra,

whereas the emission peak at 506 nm is relatively unchanged

(Fig. 4F). The absorption and emission behaviors suggest that the

binding of Cu^2þto 19 has only a small perturbation on the elec-

tronic wavefunctions involved in the optical transitions.

Upon titration of D-A substituted short H-mer 29 (SH-

1,3-(COOMe)₂-2,4-(NMe₂)₂) with TFA and Ag^þ, the spectral changes

are similar to the titration response of 19. Global spectral ﬁtting

analysis reveals that the binding of 29 to TFA or Ag^þinvolves only

a one-step process (Table 3). The magnitude of binding constant K₁

is similar to that of NMe₂substituted H-mer 19, indicating that the

binding constants are statistical and the two NMe₂groups of 29 are

independent and there is no long-range electronic communication

between them. The COOMe groups do not participate in the binding

reactions and act as spectator substituents. Unlike the case of

D-substituted H-mer 19, the titration of Cu^2þto D-A substituted

H-mer 29 led to blue shift in the absorption spectrum (Fig. 5E). The

ﬂuorescence spectrum of 29 upon titration with Cu^2þis also blue-

shifted with the appearance of structured emission proﬁle. These

results suggest that H-mer 29 binds to Cu^2þby a mechanism very

different from that for H-mer 19.

For the long H-mers, only the titration of 36 (LH) with Ag^þ

shows signiﬁcant absorption and emission changes. This is

surprising given the relatively weak electronic substitution ef-

fect on the long H-mer backbone as described above. The

UVevis and ﬂuorescence titration data for 36 with Ag^þis given

in Fig. 6.

As shown in Fig. 6A, the intensity of two absorption bands at

326 and 374 nm decrease with the increasing addition of Ag^þ.

Furthermore, there is an apparent increase of low-energy absorp-

tion tail ranging from 450 to 500 nm in the UVevis absorption

spectra. In the ﬂuorescence spectra, titration of Ag^þreduces the

radiative quantum yield of the H-mer as a result of metal ion co-

ordination (Fig. 6B). Although the observation of an isosbestic point

Scheme 12. Two-step mechanism for coordination of H-mer 19 with Ag^þ

.

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

135

Fig. 6. (A) UVevis and (B) ﬂuorescence spectroscopic titrations of H-mer 36 (17 mM in CHCl₃) with AgOTf.

in the UVevis titration curves suggests an equilibrium of two

species, the exact reaction mechanism for 36 and Ag^þhas not been

established yet. A hypothesis can be made on the assumption that

the external alkynyl moieties in 36 interact with Ag^þto form su-

pramolecular aggregates in solution. Detailed NMR spectroscopic

measurements are currently underway for further understanding.

concentrations were done at H₂O-aspirator pressure. Flash column

chromatography was carried out with silica gel 60 (230e400 mesh).

Thin-layer chromatography (TLC) was carried out with silica gel 60

F₂₅₄covered on plastic sheets and visualized by UV light or KMnO₄

stain.

Melting points (mp) were measured with a FishereJohns

melting point apparatus and are uncorrected. ¹H and ¹³C NMR

spectra were measured on a Bruker Avance 500 MHz spectrometer.

6. Conclusions

Chemical shifts (d) are reported in parts per million down ﬁeld from

the signal of the internal reference SiMe₄. Coupling constants (J) are

given in hertz. The coupling constants of some aryl proton signals

are reported as pseudo ﬁrst-order spin systems, even though they

are second-order spin systems. Infrared spectra (IR) were recorded

on a Bruker Tensor 27 spectrometer. UVevis spectra were recorded

on an Agilent 8453 UVevis or a Cary 6000i UVevis-NIR spectro-

photometer. Fluorescence spectra were measured in deoxygenated

CHCl₃at ambient temperature using a Quantamaster 10,000 ﬂuo-

rimeter. Positive-mode high-resolution mass spectra (HRMS) were

measured on a Waters GCT premier instrument equipped with

a chemical ionization (CI) ion source and a QSTAR XL hybrid

quadrupole/TOF mass spectrometer equipped with an o-MALDI ion

source (Applied Biosystems). Binding constants (K) were de-

termined by SPECFIT global analysis software package.⁹⁴

In conclusion, this report delineates the ﬁrst full account of

a new type of monodisperse H-shaped OPE/OPV co-oligomers

(H-mers) in terms of iterative synthesis, structureeproperty re-

lationship, and chemical sensing behavior. Sonogashira coupling

and HWE oleﬁnation reaction are two key steps in constructing the

H-mer backbone. For the synthesis of short H-mers, a convergent

strategy using Sonogashira coupling as the ﬁnal step has been

proven more effective than the one using the HWE reaction. For

long H-mers, however, both synthetic strategies have been dem-

onstrated successful in making the H-mer backbones. Electronic

substitution effects have been investigated by UVevis and ﬂuo-

rescence spectroscopy. Our results show that the short H-mer

backbone is more susceptible to the electronic substituents at-

tached to its termini, while the substitution effect and electronic

communication in the long H-mer backbone are considerably at-

tenuated as a result of its much longer

p

-conjugated paths. It is

7.2. Synthesis of 1,4-bis(5-bromo-2-iodostyryl)benzene (14)

noteworthy that the OPE/OPV H-mer backbone serves an asym-

metrical element to produce stereoisomers when its terminal

positions are functionalized with different substituents. The elec-

tronic properties of such substituted H-mers are dependent on the

exact substitution pattern. Short H-mers functionalized with amino

groups can bind with TFA, Ag^þ, and Cu^2þthrough acidebase in-

teractions, resulting in pronounced spectral changes in UVevis

absorption and ﬂuorescence spectra. The spectroscopic responses

attest to the applicability of using H-mers as chromophores and

ﬂuorophores to construct functional chemosensors and biosensors.

To an oven-dried round-bottom ﬂask protected under a N₂at-

mosphere were charged compound 13 (472 mg, 1.25 mmol), NaH

(75 mg, 3.1 mmol), and dry THF (10 mL). Upon gentle heating

at 50 ^ꢂC, the solution gradually turned into a light yellow color.

Aldehyde 12 (775 mg, 2.49 mmol) dissolved in THF (5 mL) was

added in small portions over a period of 1 h through a syringe. The

reaction was kept under stirring and heating for another 2 h before

workup. The small excess NaH was carefully quenched with HCl (aq

10%) and the mixture was extracted with CHCl₃three times.

The organic layer was washed with brine and dried over MgSO₄.

Removal of CHCl₃under vacuum resulted in a yellow solid, which

was recrystallized from CHCl₃/MeOH (1:1, v/v) to give 14 (380 mg,

0.549 mmol, 45%) as a yellow solid. Mp 254e255 ^ꢂC; IR (KBr) 3047,

7. Experimental section

7.1. General experimental

1880, 1628, 1565, 1533 cm^ꢀ^{1 1}H NMR (CDCl₃, 500 MHz)

; d 7.76 (d,

J¼1.5 Hz, 2H), 7.72 (d, J¼8.0 Hz, 2H), 7.58 (s, 4H), 7.26 (d, J¼16.0 Hz,

2H), 7.10 (dd, J¼8.5, 3.0 Hz, 2H), 6.98 (d, J¼16.0 Hz, 2H). Meaningful

¹³C NMR spectrum could not be obtained due to poor solubility.

HRMS (CI) m/z calcd for C₂₂H₁₄Br₂I₂691.7531, found 692.7881

[MþH]^þ.

Chemicals and reagents were purchased from commercial sup-

pliers in reagent grade and used without further puriﬁcation. Sol-

vents were dried prior to use: THF and CH₂Cl₂were distilled from

sodium/benzophenone ketyl; Et₃N and toluene were distilled from

LiH. Palladium catalysts Pd(PPh₃)₂Cl₂and Pd(PPh₃)₄were prepared

from PdCl₂according to standard procedures. Precursors

8e13,^62,85,88,8920 and 21,^90,9135,^81,83,8538 and 39,⁹²43 and 44⁹³

have been previously reported, and their synthetic procedures and

characterizations are provided as Supplementary data. All reactions

were performed in standard, dry glassware under an inert atmo-

sphere of N₂unless otherwise noted. Evaporations and

7.3. Synthesis of OPV 15

To an oven-dried round-bottom ﬂask protected under a N₂at-

mosphere were charged compound 14 (171 mg, 0.247 mmol), tri-

methylsilylacetylene (0.30 g, 3.1 mmol), PdCl₂(PPh₃)₂(25.5 mg,

136

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

0.0363 mmol), CuI (13.8 mg, 0.0726 mmol), and Et₃N (10 mL). The

solution was bubbled by N₂at rt for 5 min and then heated to 50 ^ꢂC

under stirring and N₂protection overnight. After the reaction was

completed as checked by TLC analysis, the solvent was removed by

rotary evaporation. The resulting residue was diluted with CHCl₃.

The mixture was ﬁltered through a MgSO₄pad. The solution

obtained was sequentially washed with HCl (aq 10%) and brine. The

organic layer was dried over MgSO₄and concentrated under vac-

uum to give crude 15, which was further puriﬁed by silica ﬂash

column chromatography (hexanes/CH₂Cl₂, 4:1) to yield compound

15 (135 mg, 0.202 mmol, 82%) as a yellow solid. Mp 262e263 ^ꢂC; IR

(9.69 mg, 0.0138 mmol), CuI (5.24 mg, 0.0276 mmol), and Et₃N

(3 mL). The solution was degassed by bubbling N₂at rt for 5 min

and then stirred at rt under N₂protection for 18 h. After the reaction

was completed as checked by TLC analysis, the solvent was re-

moved by rotary evaporation. The resulting residue was diluted

with CHCl₃. The mixture was ﬁltered through a MgSO₄pad. The

solution obtained was sequentially washed with HCl (aq 10%) and

brine. The organic layer was dried over MgSO₄and concentrated

under vacuum to give crude 18, which was further puriﬁed by re-

crystallization from CH₂Cl₂/hexanes to yield compound 18 (44 mg,

0.048 mmol, 70%) as a yellow solid. Mp 175e176 ^ꢂC; IR (KBr) 3060,

2948, 2840, 2208,1728,1595,1532 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

(KBr) 3031, 2959, 2898, 2155, 1633, 1478 cm^ꢀ1

500 MHz)

7.81 (br s, 2H), 7.68 (d, J¼16.5 Hz, 2H), 7.57 (s, 4H,), 7.44

(d, J¼8.5 Hz, 2H), 7.30 (dd, J¼8.0, 1.5 Hz, 2H), 7.22 (d, J¼16.0 Hz, 2H),

0.34 (s, 18H), 0.30 (s, 18H); ¹³C NMR (CDCl₃, 125 MHz)

139.3, 137.2,

;

¹H NMR (CDCl₃,

d

d 8.06e7.96 (m, 8H), 7.75 (s, 4H), 7.74e7.70 (m, 4H), 7.61 (d,

J¼8.5 Hz, 2H), 7.57e7.53 (m, 4H), 7.47e7.42 (m, 6H), 7.31 (d,

d

J¼16.5 Hz, 2H); ¹³C NMR (CDCl₃, 125 MHz)

d 166.8, 166.5, 139.7,

132.8, 130.6, 130.5, 128.2, 127.3, 126.3, 123.6, 122.3, 104.8, 103.3,

101.9, 96.4, 0.19, 0.15; HRMS (CI) m/z calcd for C₄₂H₅₀Si₄666.2990,

found 667.3103 [MþH]^þ.

137.3, 134.5, 134.4, 133.3, 132.10, 132.07, 132.0, 131.5, 131.2, 130.8,

130.4, 128.4, 128.3, 128.0, 127.8, 126.4, 124.2, 123.9, 123.8, 122.6,

95.0, 94.4, 93.3, 90.2, 52.49, 52.47 (one coincidental aromatic car-

bon not observed); HRMS (MALDI-TOF) m/z calcd for C₆₂H₄₂O₈

914.2880, found 915.3173 [MþH]^þ.

7.4. Synthesis of OPV 16

To a solution of compound 15 (135 mg, 0.202 mmol) in

MeOH/THF (1:1, 10 mL) was added K₂CO₃(50 mg, 0.36 mmol). The

mixture was stirred at rt for 1 h, then the solvent was removed by

rotary evaporation. The residue was diluted in EtOAc and sequen-

tially washed with HCl (aq 10%) and brine. The organic layer was

dried over MgSO₄and concentrated under vacuum to afford the

crude product of 16, which was further puriﬁed by silica ﬂash

column chromatography (hexanes/CH₂Cl₂, 4:1) to yield compound

16 (77 mg, 0.20 mmol, 100%) as a yellow solid. Mp >300 ^ꢂC (dec); IR

7.7. Synthesis of D-substituted short H-mer 19 (SH-(NMe₂)₄)

To an oven-dried round-bottom ﬂask protected under a N₂at-

mosphere were charged compound 16 (25 mg, 0.066 mmol),

4-iodo-N,N-dimethylaniline (140 mg, 0.568 mmol), PdCl₂(PPh₃)₂

(9.27 mg, 0.0132 mmol), CuI (5.0 mg, 0.026 mmol), and piperidine

(3 mL). The solution was degassed by bubbling with N₂at rt for

5 min and then stirred at rt under N₂protection for 24 h. After the

reaction was completed as checked by TLC analysis, the solvent was

removed by rotary evaporation. The resulting residue was diluted

with CHCl₃. The mixture was ﬁltered through a MgSO₄pad. The

solution obtained was sequentially washed with HCl (aq 10%) and

brine. The organic layer was dried over MgSO₄and concentrated

under vacuum to give crude 19, which was further puriﬁed by re-

crystallization from CHCl₃/hexanes to yield compound 19 (44 mg,

0.052 mmol, 79%) as a yellow solid. Mp >300 ^ꢂC (dec); IR (KBr)

(KBr) 3275, 3030, 2155, 2099, 1635, 1538, 1478 cm^ꢀ1

;

¹H NMR

(CDCl₃, 500 MHz)

d

7.84 (d, J¼1.5 Hz, 2H), 7.62 (d, J¼16.5 Hz, 2H),

7.56 (s, 4H), 7.48 (d, J¼8.5 Hz, 2H), 7.33 (dd, J¼8.0, 2.5 Hz, 2H), 7.19

(d, J¼16.5 Hz, 2H), 3.49 (s, 2H), 3.20 (s, 2H); ¹³C NMR (CDCl₃,

125 MHz) d 139.8, 137.3, 133.7, 131.4, 130.9, 128.7, 127.7, 126.0, 123.2,

121.9, 84.3, 83.5, 82.0, 79.3; HRMS (CI) m/z calcd for C₃₀H₁₈

378.1409, found 379.1453 [MþH]^þ

3034, 2891, 2856, 2798, 2202, 1607, 1523, 1443 cm^ꢀ1

;

¹H NMR

7.84 (br s, 2H), 7.75 (d, J¼16.0 Hz, 2H), 7.60 (s,

7.5. Synthesis of short H-mer 17 (SH)

(CDCl₃, 500 MHz)

d

4H), 7.48e7.43 (m, 10H), 7.34 (d, J¼8.0 Hz, 2H), 7.26 (d, J¼16.5 Hz,

2H), 6.70e6.67 (m, 8H), 3.10 (s, 12H), 2.99 (s, 12H). Meaningful ¹³C

NMR spectrum could not be obtained due to poor solubility; HRMS

(MALDI-TOF) m/z calcd for C₆₂H₅₄N₄854.4348, found 855.5049

[MþH]^þ.

To an oven-dried round-bottom ﬂask protected under a N₂at-

mosphere were charged compound 16 (30 mg, 0.079 mmol),

iodobenzene (129 mg, 0.635 mmol), PdCl₂(PPh₃)₂(11.2 mg,

0.0159 mmol), CuI (6.0 mg, 0.032 mmol), and piperidine (3 mL). The

solution was degassed by bubbling with N₂at rt for 5 min and then

heated to 50 ^ꢂC under stirring and N₂protection overnight. After

the reaction was completed as checked by TLC analysis, the solvent

was removed by rotary evaporation. The resulting residue was di-

luted with CHCl₃. The mixture was ﬁltered through a MgSO₄pad.

The solution obtained was sequentially washed with HCl (aq 10%)

and brine. The organic layer was dried over MgSO₄and concen-

trated under vacuum to give crude 17, which was further puriﬁed

by recrystallization from CHCl₃/hexanes to yield H-mer 17 (36 mg,

0.053 mmol, 67%) as a yellow solid. Mp >300 ^ꢂC (dec); IR (KBr)

3262, 3052, 2208, 1631, 1597, 1499 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

7.8. Synthesis of OPE 22

Compound 21 (80 mg, 0.52 mmol), methyl 2-iodobenzoate

(273 mg, 1.04 mmol), PdCl₂(PPh₃)₂(36 mg, 0.052 mmol), and CuI

(20 mg, 0.104 mmol) were added to Et₃N (10 mL). The solution was

bubbled by N₂at rt for 5 min and then stirred for 3 h at rt. After the

reaction was completed as checked by TLC analysis, the solvent was

removed by rotary evaporation. The resulting residue was diluted

with CHCl₃. The mixture was ﬁltered through a MgSO₄pad. The

solution obtained was sequentially washed with HCl (aq 10%) and

brine. The organic layer was dried over MgSO₄and concentrated

under vacuum to give crude 22, which was further puriﬁed by silica

ﬂash column chromatography (hexanes/CH₂Cl₂, 1:1) to yield com-

pound 22 (139 mg, 0.329 mmol, 63%) as a yellow solid. Mp

144e145 ^ꢂC; IR (KBr) 2999, 2950, 2215, 1719, 1687, 1597, 1564, 1500,

d

7.91 (br s, 2H), 7.73 (d, J¼17.0 Hz, 2H), 7.61 (s, 4H), 7.60e7.57 (m,

8H), 7.55 (d, J¼8.5 Hz, 2H), 7.41e7.37 (m, 14H), 7.28 (d, J¼14.5 Hz,

2H). Meaningful ¹³C NMR could not be obtained due to poor solu-

bility; HRMS (MALDI-TOF) m/z calcd for C₅₄H₃₄682.2661, found

683.2675 [M]^þ.

1446 cm^ꢀ^{1 1}H NMR (CDCl₃, 500 MHz)

; d 10.74 (s, 1H), 8.14 (s, 1H)

7.6. Synthesis of A-substituted short H-mer 18 (SH-(COOMe)₄)

8.04 (d, J¼8.5 Hz, 1H), 8.01 (d, J¼8.0 Hz, 1H), 7.77 (d, J¼7.0 Hz, 1H),

7.71e7.69 (m, 2H), 7.66 (d, J¼8.0, 1H), 7.57e7.51 (m, 2H), 7.47e7.41

To an oven-dried round-bottom ﬂask protected under a N₂at-

mosphere were charged compound 16 (26 mg, 0.069 mmol),

methyl 2-iodobenzoate (108 mg, 0.412 mmol), PdCl₂(PPh₃)₂

(m, 2H), 3.99 (s, 3H), 3.97 (s, 3H); ¹³C NMR (CDCl₃, 125 MHz)

d 191.8,

166.5, 166.2, 136.41, 136.39, 134.4, 134.3, 133.6, 132.08, 132.04,

131.95, 131.82, 130.9, 130.7, 130.4, 129.0, 128.6, 126.5, 124.4, 123.2,

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

137

122.9, 96.7, 92.9, 91.5, 89.9, 52.5, 52.4; HRMS (CI) m/z calcd for

7.12. Synthesis of methyl 2-((3-formyl-4-((triisopropylsilyl)

ethynyl)phenyl)ethynyl)benzoate (26)

C₂₇H₁₈O₅422.1154, found 423.1265 [MþH]^þ.

Compound 25 (181 mg, 0.583 mmol), methyl 2-iodobenzoate

(153 mg, 0.583 mmol), PdCl₂(PPh₃)₂(21 mg, 0.0293 mmol), and CuI

(11.1 mg, 0.0586 mmol) were added to Et₃N (8 mL). The solution

was bubbled with N₂at rt for 5 min and then stirred at rt and under

N₂protection for 5 h. After the reaction was completed as checked

by TLC analysis, the solvent was removed by rotary evaporation.

The resulting residue was diluted with CHCl₃. The mixture was

ﬁltered through a MgSO₄pad. The solution obtained was sequen-

tially washed with aq HCl (10%) and brine. The organic layer was

dried over MgSO₄and concentrated under vacuum to give crude 26,

which was further puriﬁed by silica ﬂash column chromatography

(hexanes/CH₂Cl₂, 3:2) to yield compound 26 (196 mg, 0.441 mmol,

76%) as a white solid. Mp 82e83 ^ꢂC; IR (KBr) 2942, 2890, 2865,

7.9. Synthesis of 5-bromo-2-((triisopropylsilyl)ethynyl)

benzaldehyde (23)

Compound 12 (1.62 g, 5.20 mmol), triisopropylsilylacetylene

(1.15 mL, 0.950 g, 5.20 mmol), PdCl₂(PPh₃)₂(46 mg, 0.065 mmol),

and CuI (25 mg, 0.13 mmol) were added to Et₃N (20 mL). The so-

lution was bubbled with N₂at rt for 5 min and then stirred at rt and

under N₂protection for 24 h. After the reaction was completed as

checked by TLC analysis, the solvent was removed by rotary evap-

oration. The resulting residue was diluted with CHCl₃. The mixture

was ﬁltered through a MgSO₄pad. The solution obtained was se-

quentially washed with HCl (aq 10%) and brine. The organic layer

was dried over MgSO₄and concentrated under vacuum to give

crude 23, which was further puriﬁed by silica ﬂash column chro-

matography (hexanes/CH₂Cl₂, 4:1) to yield compound 23 (1.78 g,

4.87 mmol, 94%) as a colorless oil. IR (KBr) 2944, 2891, 2866, 2736,

2153, 1710, 1694, 1600, 1493, 1463, 1450, 1384 cm^ꢀ1

(CDCl₃, 500 MHz)

;

¹H NMR

d

10.60 (s, 1H), 8.09 (d, J¼1.0 Hz, 1H), 7.99 (d,

J¼8.5 Hz, 1H), 7.72 (dd, J¼8.5, 1.0 Hz, 1H), 7.64 (d, J¼8.0 Hz, 1H), 7.58

(d, J¼8.5 Hz, 1H), 7.51 (t, J¼8.5 Hz, 1H), 7.41 (t, J¼8.0 Hz, 1H), 3.97 (s,

2156, 1695, 1582, 1469, 1383 cm^ꢀ^{1 1}H NMR (CDCl₃, 500 MHz)

;

3H), 1.16 (s, 21H); ¹³C NMR (CDCl₃, 125 MHz)

d 191.0, 166.5, 136.38,

d

10.53 (s,1H), 8.05 (d, J¼2.0 Hz,1H), 7.67 (dd, J¼8.5,1.5 Hz,1H), 7.47

136.35, 134.3, 134.0, 132.1, 132.0, 130.8, 130.3, 128.6, 126.6, 124.3,

123.2, 102.0, 101.4, 92.8, 91.4, 52.4, 18.8, 11.4; HRMS (CI) m/z calcd

for C₂₈H₃₂O₄Si 444.2121, found 445.2143 [MþH]^þ.

(d, J¼8.0 Hz, 1H), 1.15 (s, 21H); ¹³C NMR (CDCl₃, 125 MHz)

d 190.4,

137.5, 136.7, 135.4, 130.1, 125.9, 123.4, 101.1, 100.9, 18.8, 11.4; HRMS

(CI) m/z calcd for C₁₈H₂₅BrOSi 364.0858, found 365.1071 [MþH]^þ.

7.13. Synthesis of methyl 2-((4-ethynyl-3-formylphenyl)

ethynyl)benzoate (27)

7.10. Synthesis of 2-((triisopropylsilyl)ethynyl)-5-

((trimethylsilyl)ethynyl)benzaldehyde (24)

To a solution of compound 26 (195 mg, 0.439 mmol) in THF

(8 mL) was added TBAF (0.05 mL, 1 M in THF, 0.05 mmol). The

mixture was stirred at rt for 10 min, and the solvent was removed

by rotary evaporation. The residue was dissolved in CHCl₃and se-

quentially washed with HCl (aq 10%) and brine. The organic layer

dried over MgSO₄. Filtration to remove MgSO₄followed by evapo-

ration under vacuum afforded the crude product, which was pu-

riﬁed by silica ﬂash column chromatography (hexanes/CH₂Cl₂, 7:3)

to yield compound 27 as a yellow solid (99 mg, 0.34 mmol, 78%).

Mp 120e121 ^ꢂC; IR (KBr) 3251, 2960, 2855, 2152, 2101, 1724, 1692,

Compound 23 (417 mg, 1.14 mmol), trimethylsilylacetylene

(0.322 mL, 2.28 mmol, mmol), PdCl₂(PPh₃)₂(20 mg, 0.029 mmol),

and CuI (11 mg, 0.057 mmol) were added to Et₃N (10 mL). The

solution was bubbled with N₂at rt for 5 min and then stirred at

60 ^ꢂC under N₂protection for 12 h. After the reaction was com-

pleted as checked by TLC analysis, the solvent was removed by

rotary evaporation. The resulting residue was diluted with CHCl₃.

The mixture was ﬁltered through a MgSO₄pad. The solution

obtained was sequentially washed with HCl (aq 10%) and brine. The

organic layer was dried over MgSO₄and concentrated under vac-

uum to give crude 24, which was further puriﬁed by silica ﬂash

column chromatography (hexanes/CH₂Cl₂, 17:1) to yield compound

24 (431 mg, 1.13 mmol, 99%) as a colorless oil. ¹H NMR (CDCl₃,

1600, 1566, 1492, 1433, 1389 cm^ꢀ^{1 1}H NMR (CDCl₃, 500 MHz)

;

d

10.52 (s, 1H), 8.10 (d, J¼1.5 Hz, 1H), 8.01 (d, J¼8.0 Hz, 1H), 7.75 (dd,

J¼8.0, 1.5 Hz, 1H), 7.66 (d, J¼8.0 Hz, 1H), 7.61 (d, J¼8.5 Hz, 1H), 7.53

(t, J¼8.5 Hz, 1H), 7.43 (t, J¼8.0 Hz, 1H), 3.98 (s, 3H), 3.58 (s, 1H); ¹³C

NMR (CDCl₃, 125 MHz)

d 190.8, 166.5, 136.7, 136.5, 134.4, 134.1,

500 MHz)

d

10.58 (s, 1H), 8.01 (d, J¼1.5 Hz, 1H), 7.61 (dd, J¼8.0,

1.5 Hz,1H), 7.54 (d, J¼8.0 Hz, 1H),1.16 (s, 21H), 0.28 (s, 9H); ¹³C NMR

132.2, 132.0, 130.8, 130.7, 128.7, 125.0, 124.9, 123.1, 92.6, 91.6, 86.0,

79.3, 52.5; HRMS (CI) m/z calcd for C₁₉H₁₂O₃288.0786, found

289.0852 [MþH]^þ.

(CDCl₃, 125 MHz)

d 190.9, 136.5, 136.3, 133.9, 130.7, 126.6, 124.1,

103.4, 101.9, 101.3, 98.0, 18.8, 11.4, 0.0; HRMS (CI) m/z calcd for

C₂₃H₃₄OSi₂382.2148, found 383.2285 [MþH]^þ.

7.14. Synthesis of OPE 28

7.11. Synthesis of 5-ethynyl-2-((triisopropylsilyl)ethynyl)

benzaldehyde (25)

Compound 27 (99 mg, 0.34 mmol), 4-iodo-N,N-dimethylaniline

(85 mg, 0.34 mmol), PdCl₂(PPh₃)₂(12 mg, 0.017 mmol), and CuI

(6.5 mg, 0.034 mmol) were added to Et₃N (6 mL). The solution was

bubbled with N₂at rt for 5 min and then stirred at 40 ^ꢂC under N₂

protection for 7 h. After the reaction was completed as checked by

TLC analysis, the solvent was removed by rotary evaporation. The

resulting residue was diluted with CHCl₃. The mixture was ﬁltered

through a MgSO₄pad. The solution obtained was sequentially

washed with HCl (aq 10%) and brine. The organic layer was dried

over MgSO₄and concentrated under vacuum to give crude 28,

which was further puriﬁed by silica ﬂash column chromatography

(hexanes/CH₂Cl₂, 1:1) to yield compound 28 (65 mg, 0.16 mmol,

47%) as a white solid. Mp 151e152 ^ꢂC; IR (KBr) 2925, 2198, 1730,

To a solution of compound 24 (431 mg,1.13 mmol) in MeOH/THF

(12 mL,1:1) was added K₂CO₃(50 mg, 0.36 mmol). The mixture was

stirred at rt for 1 h, then the solvent was removed by rotary

evaporation. The residue was diluted in CH₂Cl₂and sequentially

washed with HCl (aq 10%) and brine. The organic layer was dried

over MgSO₄and concentrated under vacuum to afford crude 25,

which was further puriﬁed by silica ﬂash column chromatography

(hexanes/CH₂Cl₂, 4:1) to yield compound 25 (371 mg, 1.2 mmol,

100%) as a colorless oil. ¹H NMR (CDCl₃, 500 MHz)

8.02 (d, J¼2.0 Hz, 1H), 7.63 (dd, J¼7.5, 2.0 Hz, 1H), 7.55 (d, J¼7.5 Hz,

1H), 3.23 (s, 1H), 1.15 (s, 21H); ¹³C NMR (CDCl₃, 125 MHz)

190.8,

d 10.57 (s, 1H),

d

1688, 1610, 1526, 1492, 1446, 1432, 1384 cm^ꢀ1

500 MHz)

;

¹H NMR (CDCl₃,

136.8, 136.3, 134.0, 130.8, 127.1, 123.0, 101.69, 101.63, 82.2, 80.3, 18.8,

11.4; HRMS (CI) m/z calcd for C₂₀H₂₆OSi 310.1753, found 311.1815

[MþH]^þ.

d

10.64 (s, 1H), 8.10 (d, J¼1.0 Hz, 1H), 8.01 (d, J¼8.0 Hz,

1H), 7.72 (dd, J¼8.5, 1.0 Hz, 1H), 7.66 (d, J¼8.5 Hz, 1H), 7.58 (d,

J¼8.5 Hz, 1H), 7.52 (t, J¼8.5 Hz, 1H), 7.45 (d, J¼9.0 Hz, 1H), 7.42 (t,

138

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

J¼8.0 Hz, 1H), 6.68 (d, J¼9.0 Hz, 1H), 3.99 (s, 3H), 3.02 (s, 6H); ¹³C

(s, 2H), 1.22 (s, 42H); ¹³C NMR (CDCl₃, 125 MHz)

d 139.3, 137.1, 133.4,

NMR (CDCl₃, 125 MHz)

d

191.5, 166.6, 150.9, 136.5, 135.4, 134.3,

130.7, 130.6, 128.3, 127.4, 126.1, 123.1, 122.4, 105.0, 98.4, 83.5, 78.9,

19.0, 11.6; HRMS (CI) m/z calcd for C₄₈H₅₈Si₂690.4077, found

691.4300 [MþH]^þ.

133.2, 132.9, 132.1, 132.0, 130.8, 130.7, 128.5, 127.9, 123.4, 123.0,

111.9, 108.7, 100.6, 93.2, 90.9, 83.7, 52.5, 40.3; HRMS (CI) m/z calcd

for C₂₇H₂₁NO₃407.1521, found 408.1653 [MþH]^þ.

7.18. Synthesis of OPE/OPV 33

7.15. Synthesis of OPV 30

To an oven-dried round-bottom ﬂask protected under a N₂at-

mosphere were charged compound 32 (220 mg, 0.318 mmol),

methyl 2-iodobenzoate (168 mg, 0.637 mmol), PdCl₂(PPh₃)₂

(22 mg, 0.032 mmol), CuI (12 mg, 0.064 mmol), and Et₃N (10 mL).

The solution was bubbled with N₂at rt for 5 min and then stirred at

40 ^ꢂC under N₂protection for 12 h. After the reaction was com-

pleted as checked by TLC analysis, the solvent was removed by

rotary evaporation. The resulting residue was diluted with CHCl₃.

The mixture was ﬁltered through a MgSO₄pad. The solution

obtained was sequentially washed with HCl (aq 10%) and brine. The

organic layer was dried over MgSO₄and concentrated under vac-

uum to give crude 33, which was further puriﬁed by silica ﬂash

column chromatography (hexanes/CH₂Cl₂, 1:4) to yield compound

33 (233 mg, 0.243 mmol, 76%) as a yellow solid. Mp 185e186 ^ꢂC; IR

(KBr) 3032, 2943, 2891, 2864, 2210, 2148, 1731, 1631, 1597, 1567,

To an oven-dried round-bottom ﬂask protected under a N₂at-

mosphere were charged compound 13 (51.8 mg, 0.137 mmol), NaH

(9.9 mg, 0.41 mmol), and dry THF (4 mL). Upon gentle heating at

40 ^ꢂC, the solution gradually turned into a light yellow color. Al-

dehyde 23 (100 mg, 0.274 mmol) dissolved in THF (4 mL) was added

in small portions over a period of 1 h through a syringe. The re-

action was kept under stirring and heating for another 0.5 h before

workup. The small excess NaH was carefully quenched with HCl (aq

10%) and the mixture was extracted with CHCl₃three times. The

organic layer was dried over MgSO₄and concentrated under vac-

uum to give crude 30, which was further puriﬁed by silica ﬂash

column chromatography (hexanes/CH₂Cl₂, 9:1) to yield compound

30 (50 mg, 0.062 mmol, 45%) as a yellow solid. Mp 174e175 ^ꢂC; IR

(KBr) 2941, 2890, 2864, 2152, 1631, 1579, 1560, 1541, 1510,

1467 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

d

7.83 (d, J¼1.5 Hz, 2H), 7.67

1489 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

d

8.02 (dd, J¼8.0, 1.0 Hz, 2H),

(d, J¼16.0 Hz, 2H), 7.52 (s, 4H), 7.36 (d, J¼8.5 Hz, 2H), 7.31 (dd, J¼7.5,

7.92 (br s, 2H), 7.75 (d, J¼16.5 Hz, 2H), 7.70 (d, J¼7.0 Hz, 2H), 7.56 (s,

4H), 7.54e7.51 (m, 4H), 7.44e7.42 (m, 4H), 7.24 (d, J¼16.5 Hz, 2H),

1.5 Hz, 2H), 7.14 (d, J¼16.5 Hz, 2H), 1.18 (s, 42H); ¹³C NMR (CDCl₃,

125 MHz)

d

141.0, 137.0, 134.7, 131.0, 130.3, 127.53, 127.46, 125.8,

4.00 (s, 6H), 1.21 (s, 42H); ¹³C NMR (CDCl₃, 125 MHz)

d 166.8, 139.4,

123.1, 121.6, 104.6, 97.6, 19.0, 11.6; HRMS (CI) m/z calcd for

137.1, 134.3, 133.4, 132.1, 132.0, 130.79, 130.68, 130.4, 128.4, 128.7,

127.4, 126.3, 123.74, 123.70, 122.8, 105.3, 98.3, 94.3, 90.1, 52.5, 19.0,

11.6; HRMS (CI) m/z calcd for C₆₄H₇₀O₄Si₂958.4813, found

959.5306 [MþH]^þ.

C₄₄H₅₆Br₂Si₂800.2267, found 801.2343 [MþH]^þ.

7.16. Synthesis of OPV 31

Compound 30 (305 mg, 0.381 mmol), trimethylsilylacetylene

(0.14 g, 1.4 mmol), PdCl₂(PPh₃)₂(26.8 mg, 0.0381 mmol), and CuI

(14.5 mg, 0.0762 mmol) were added to Et₃N (10 mL). The solution

was bubbled with N₂at rt for 5 min and then stirred at 60 ^ꢂC under

N₂protection for 12 h. After the reaction was completed as checked

by TLC analysis, the solvent was removed by rotary evaporation.

The resulting residue was diluted with CHCl₃. The mixture was

ﬁltered through a MgSO₄pad. The solution obtained was sequen-

tially washed with HCl (aq 10%) and brine. The organic layer was

dried over MgSO₄and concentrated under vacuum to give crude 31,

which was further puriﬁed by silica ﬂash column chromatography

(hexanes/CH₂Cl₂, 19:1) to yield compound 31 (297 mg, 0.356 mmol,

93%) as a yellow solid. Mp 211e212 ^ꢂC; IR (KBr) 2943, 2893, 2865,

2154, 1632, 1595, 1534, 1511, 1477 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

7.19. Synthesis of OPE/OPV 34

To a solution of compound 33 (233 mg, 0.243 mmol) in THF

(8 mL) was added TBAF (0.1 mL, 1 M in THF, 0.1 mmol). The mixture

was stirred at rt for 5 min, then the solvent was removed by rotary

evaporation. The residue was dissolved in CHCl₃and sequentially

washed with HCl (aq 10%) and brine. The organic layer dried over

MgSO₄. Filtration to remove MgSO₄followed by evaporation under

vacuum afforded crude product 34, which was puriﬁed with silica

ﬂash column chromatography (hexanes/CH₂Cl₂, 9:1) to yield

compound 34 as a yellow solid (143 mg, 0.221 mmol, 91%). Mp

>300 ^ꢂC (dec); IR (KBr) 3290, 3029, 2953, 2920, 2850, 2212, 2099,

1724, 1667, 1646, 1598, 1565, 1489 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

d

8.02 (d, J¼8.5 Hz, 2H), 7.92 (d, J¼1.5 Hz, 2H), 7.69 (d, J¼8.5 Hz, 2H),

d

7.82 (br s, 2H), 7.71 (d, J¼16.5 Hz, 2H), 7.53 (s, 4H), 7.44 (d,

J¼7.0 Hz, 2H) 7.28 (dd, J¼8.0, 1.0 Hz, 2H), 7.19 (d, J¼16.5 Hz, 2H), 1.19

(s, 42H), 0.29 (s, 18H); ¹³C NMR (CDCl₃, 125 MHz)

139.2, 137.1,

7.65 (d, J¼16.0 Hz, 2H), 7.59 (s, 4H), 7.55e7.52 (m, 4H), 7.44e7.41

(m, 4H), 7.24 (d, J¼17.0 Hz, 2H), 3.40 (s, 6H), 3.51 (s, 2H); ¹³C NMR

d

(CDCl₃, 125 MHz) d 166.8, 139.7, 137.1, 134.4, 133.5, 132.0, 131.1,

133.3, 130.6, 130.5, 128.1, 127.7, 126.2, 123.5, 122.7, 105.2, 104.9, 98.2,

96.2, 19.0, 11.6, 0.14; HRMS (CI) m/z calcd C₅₄H₇₄Si₄834.4868, found

835.5097 [MþH]^þ.

130.8, 130.4, 128.4, 128.0, 127.5, 126.0, 124.2, 123.6, 121.3 (of the 16

aromatic and alkenyl carbons, one coincidental peak not observed),

94.0, 90.2, 84.0, 82.0, 52.5; HRMS (CI) m/z calcd for C₄₆H₃₀O₄

646.2144 found 647.2826 [MþH]^þ.

7.17. Synthesis of OPV 32

7.20. Synthesis of D-A substituted short H-mer 29 (SH-1,3-

To a solution of compound 31 (335 mg, 0.401 mmol) in MeOH/

THF (12 mL,1:1) was added K₂CO₃(50 mg, 0.36 mmol). The mixture

was stirred at rt for 15 min, then the solvent was removed by rotary

evaporation. The residue was diluted with EtOAc and sequentially

washed with HCl (aq 10%) and brine. The organic layer was dried

over MgSO₄and concentrated under vacuum to afford crude 32,

which was further puriﬁed by silica ﬂash column chromatography

(hexanes/CH₂Cl₂, 19:1) to yield compound 32 (220 mg, 0.318 mmol,

79%) as a yellow solid. Mp 143e144 ^ꢂC; IR (KBr) 3300, 3033, 2942,

(COOMe)₂-2,4-(NMe₂)₂)

To an oven-dried round-bottom ﬂask protected under a N₂

atmosphere were charged compound 34 (47 mg, 0.073 mmol),

4-iodo-N,N-dimethylaniline (36 mg, 0.15 mmol), PdCl₂(PPh₃)₂

(5.1 mg, 0.0072 mmol), CuI (2.8 mg, 0.015 mmol), piperidine

(2.5 mL), and dry THF (2.5 mL). The solution was degassed by N₂

bubbling at rt for 5 min and then stirred at 30 ^ꢂC under N₂pro-

tection for 12 h. After the reaction was completed as checked by TLC

analysis, the solvent was removed by rotary evaporation. The

resulting residue was diluted with CHCl₃. The mixture was ﬁltered

through a MgSO₄pad. The solution obtained was sequentially

2891, 2864, 2149, 1632, 1596, 1536, 1511, 1464 cm^ꢀ1

(CDCl₃, 500 MHz)

7.87 (d, J¼1.0 Hz, 2H), 7.74 (d, J¼16.0 Hz, 2H),

7.55 (s, 4H), 7.34 (dd, J¼8.5, 1.0 Hz, 2H), 7.21 (d, J¼16.5 Hz, 2H), 3.21

;

¹H NMR

d

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

139

washed with HCl (aq 10%) and brine. The organic layer was dried

over MgSO₄and concentrated under vacuum to give crude 29,

which was puriﬁed by silica ﬂash column chromatography (CH₂Cl₂)

to yield compound 29 (30 mg, 0.034 mmol, 47%) as a yellow solid.

Mp 225e226 ^ꢂC; IR (KBr) 2960, 2930, 2860, 2195, 1728, 1609, 1524,

29.6, 29.58, 29.54, 29.5, 26.2, 22.9, 14.3, 0.14; HRMS (CI) m/z calcd

for C₄₀H₅₇NO₂Si 611.4159, found 612.4176 [MþH]^þ.

7.23. Synthesis of 4-((2,5-bis(decyloxy)-4-ethynylphenyl)

ethynyl)benzonitrile (41)

1488, 1464 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

d

8.01 (d, J¼7.5 Hz, 2H),

7.91 (s, 2H), 7.76 (d, J¼16.5 Hz, 2H), 7.69 (d, J¼8.5 Hz, 2H), 7.61 (s,

4H), 7.54e7.47 (m, 8H), 7.43e7.39 (m, 4H), 7.28 (d, J¼16.5 Hz, 2H),

6.70 (d, J¼9.0 Hz, 4H), 4.00 (s, 6H), 3.00 (s, 12H); ¹³C NMR (CDCl₃,

To a solution of compound 40 (428 mg, 0.699 mmol) in

MeOH/THF (10 mL, 1:1) was added K₂CO₃(100 mg, 0.724 mmol).

The mixture was stirred at rt for 30 min, then the reaction solvent

was removed by rotary evaporation. The residue was diluted with

EtOAc and sequentially washed with HCl (aq 10%) and brine. The

organic layer was dried over MgSO₄and concentrated under vac-

uum to afford crude 41, which was further puriﬁed by silica ﬂash

column chromatography (hexanes/CH₂Cl₂, 4:1) to yield compound

41 (333 mg, 0.617 mmol, 88%) as a colorless oil. IR (KBr) 3290, 3256,

2925, 2852, 2226, 2155, 2102, 1639, 1605, 1508, 1494, 1466, 1409,

125 MHz)

d 166.9, 150.5, 138.5, 137.3, 134.3, 132.9, 132.4, 131.98,

131.95, 130.8, 130.48, 130.43, 128.2, 127.4, 126.6, 123.9, 123.6, 122.6,

112.1, 109.9 (of the 20 aromatic and alkenyl carbons, one co-

incidental peak not observed), 98.2, 94.6, 89.7, 86.3, 52.5, 40.4;

HRMS (CI) m/z calcd for C₆₂H₄₈N₂O₄884.3614, found 885.3608

[MþH]^þ.

1387 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

d

7.64 (d, J¼8.5 Hz, 2H), 7.60

7.21. Synthesis of long OPE/OPV H-mer 36 (LH)

(d, J¼8.5 Hz, 2H), 7.00 (s, 1H), 6.99 (s, 1H), 4.03e3.99 (m, 4H), 3.37

(s, 1H), 1.86e1.80 (m, 4H), 1.55e1.46 (m, 4H), 1.38e1.26 (m, 24H),

Compound 16 (16 mg, 0.044 mmol), 35 (106 mg, 0.174 mmol),

PdCl₂(PPh₃)₂(6.11 mg, 0.00870 mmol), and CuI (3.31 mg,

0.0174 mmol) were added to Et₃N (8 mL). The solution was

degassed by N₂bubbling at rt for 5 min and then stirred for 4 h at rt,

then heated to 50 ^ꢂC under stirring and N₂protection for 20 h. After

the reaction was completed as checked by TLC analysis, the solvent

was removed by rotary evaporation. The resulting residue was di-

luted with CHCl₃. The mixture was ﬁltered through a MgSO₄pad.

The solution obtained was sequentially washed with HCl (aq 10%)

and brine. The organic layer was dried over MgSO₄and concen-

trated under vacuum to give crude 36, which was further puriﬁed

by silica ﬂash column chromatography (hexanes/CH₂Cl₂, 7:3) to

yield compound 36 (36 mg, 0.016 mmol, 36%) as a colorless oil. IR

(KBr) 2956, 2925, 2854, 2153, 1698, 1683, 1650, 1635, 1558, 1539,

0.90e0.87 (m, 6H); ¹³C NMR (CDCl₃,125 MHz)

d 154.3,153.9,132.21,

132.17, 128.5, 118.7, 117.8, 117.1, 113.9, 113.5, 111.7, 93.2, 90.5, 83.0,

80.0, 69.9, 69.7, 32.10, 32.09, 29.9, 29.8, 29.6, 29.53, 29.46, 29.3,

26.2, 26.1, 22.9, 14.3; HRMS (CI) m/z calcd for C₃₇H₄₉NO₂539.3763,

found 540.3759 [MþH]^þ.

7.24. Synthesis of ((2,5-bis(decyloxy)-4-((4-methoxyphenyl)

ethynyl)phenyl)ethynyl)trimethylsilane (45)

Compound 44 (108 mg, 0.818 mmol), 35 (500 mg, 0.818 mmol),

PdCl₂(PPh₃)₂(14 mg, 0.020 mmol), and CuI (7.8 mg, 0.041 mmol)

were added to Et₃N (15 mL). The solution was bubbled with N₂at rt

for 5 min and then stirred under N₂protection overnight. After the

reaction was completed as checked by TLC analysis, the solvent was

removed by rotary evaporation. The resulting residue was diluted

with CHCl₃. The mixture was ﬁltered through a MgSO₄pad. The

solution obtained was sequentially washed with HCl (aq 10%) and

brine. The organic layer was dried over MgSO₄and concentrated

under vacuum to give crude 45, which was further puriﬁed by silica

ﬂash column chromatography (hexanes/CH₂Cl₂, 17:1) to yield

compound 45 (463 mg, 0.750 mmol, 92%) as a colorless oil. IR (KBr)

2955, 2923, 2854, 2209, 2153, 1607, 1570, 1514, 1497, 1468, 1442,

1504, 1470,1415 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

d 7.90 (s, 2H), 7.78

(d, J¼16.0 Hz, 2H), 7.58 (s, 4H), 7.54 (d, J¼8.5 Hz, 2H), 7.40 (d,

J¼8.5 Hz, 2H), 7.27 (d, J¼16.0 Hz, 2H), 7.01 (s, 2H), 7.00 (s, 4H), 6.99

(s, 2H), 4.06e3.99 (m, 16H), 1.90e1.18 (m, 128H), 0.92e0.83 (m,

24H), 0.30 (s, 18H), 0.29 (s, 18H); ¹³C NMR (CDCl₃, 125 MHz)

d 154.4,

153.81, 153.8, 139.0, 137.3, 132.8, 130.7, 130.3, 128.1, 127.5, 126.5,

123.7, 122.5, 117.7, 117.6, 117.11, 117.06, 114.4, 114.2, 101.3, 100.6,

100.5, 94.9, 93.5, 93.1, 87.9, 70.0, 69.9, 69.8, 32.1, 29.9, 29.83, 29.77,

29.7, 29.64, 29.29.62, 29.6, 29.4, 26.3, 26.1, 22.9, 14.3, 0.19; HRMS

(MALDI-TOF) m/z calcd for C₁₅₄H₂₂₆O₈Si₄2315.6388, found

2315.7135 [M]^þ.

1410, 1388 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

6.94 (s, 1H), 6.93 (s, 1H), 6.86 (d, J¼9.5 Hz, 2H), 3.40e3.96 (m, 4H),

3.82 (s, 3H), 1.83e1.78 (m, 4H), 1.53e1.50 (m, 4H), 1.36e1.25 (m,

24H), 0.90e0.86 (m, 6H), 0.26 (s, 9H); ¹³C NMR (CDCl₃, 125 MHz)

d

7.46 (d, J¼9.5 Hz, 2H),

7.22. Synthesis of 4-((2,5-bis(decyloxy)-4-((trimethylsilyl)

ethynyl)phenyl)ethynyl)benzonitrile (40)

d 159.8, 154.4, 153.5, 133.2, 117.5, 116.9, 115.8, 115.0, 114.3, 114.1,

113.5, 101.5, 99.9, 95.2, 84.8, 69.8, 69.6, 55.3, 34.8, 32.1, 29.85, 29.80,

29.77, 29.63, 29.56, 29.53, 26.3, 26.2, 22.9, 14.3, 0.16; HRMS (CI) m/z

calcd for C₄₀H₆₀O₃Si 616.4321, found 617.4386 [MþH]^þ.

Compound 39 (100 mg, 0.787 mmol), 35 (484 mg, 0.787 mmol),

PdCl₂(PPh₃)₂(27 mg, 0.039 mmol), and CuI (15 mg, 0.079 mmol)

were added to Et₃N (20 mL). The solution was bubbled by N₂at rt

for 5 min and then stirred at rt for 4 h under N₂protection. After the

reaction was completed as checked by TLC analysis, the solvent was

removed by rotary evaporation. The resulting residue was diluted

with CHCl₃. The mixture was ﬁltered through a MgSO₄pad. The

solution obtained was sequentially washed with HCl (aq 10%) and

brine. The organic layer was dried over MgSO₄and concentrated

under vacuum to give crude 40, which was further puriﬁed by silica

ﬂash column chromatography (hexanes/CH₂Cl₂, 4:1) to yield

compound 40 (482 mg, 0.787 mmol, 100%) as a colorless oil. IR

(KBr) 2925, 2854, 2228, 2212, 2153, 1604, 1508, 1493, 1468, 1412,

7.25. Synthesis of 1,4-bis(decyloxy)-2-ethynyl-5-((4-

methoxyphenyl)ethynyl)benzene (46)

To a solution of compound 45 (463 mg, 0.750 mmol) in

MeOH/CHCl₃(16 mL, 1:1) was added K₂CO₃(200 mg, 1.44 mmol).

The mixture was stirred at rt for 2 h, then the reaction solvent was

removed by rotary evaporation. The residue was diluted with

CH₂Cl₂and sequentially washed with HCl (aq 10%) and brine. The

organic layer was dried over MgSO₄and concentrated under vac-

uum to afford crude 46, which was further puriﬁed by silica ﬂash

column chromatography (hexanes/CH₂Cl₂, 17:1) to yield compound

46 (392 mg, 0.72 mmol, 96%) as a white solid. Mp 40e41 ^ꢂC; IR

(KBr) 3293, 2959, 2920, 2851, 2215, 2152, 1610, 1569, 1516, 1499,

1384 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

d

7.63 (d, J¼8.0 Hz, 2H), 7.59

(d, J¼8.0 Hz, 2H), 6.96 (s, 2H), 4.01e3.97 (m, 4H), 1.84e1.80 (m, 4H),

1.55e1.49 (m, 4H), 1.37e1.28 (m, 24H), 0.90e0.87 (m, 6H); ¹³C NMR

1471, 1410, 1392 cm^ꢀ^{1 1}H NMR (CDCl₃, 500 MHz)

; d 7.42 (d,

(CDCl₃, 125 MHz)

115.1, 113.1, 111.6, 101.1, 101.0, 93.2, 90.7, 69.8, 69.7, 32.1, 29.9, 29.8,

d

154.3, 154.0, 132.2, 132.1, 128.6, 118.7, 117.3, 117.1,

J¼11.0 Hz, 2H), 6.98 (s, 1H), 6.97 (s, 1H), 6.88 (d, J¼11.0 Hz, 2H),

4.01e3.97 (m, 4H), 3.82 (s, 3H), 3.33 (s, 1H), 1.85e1.79 (m, 4H),

140

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

1.54e1.45 (m, 4H), 1.36e1.26 (m, 24H), 0.90e0.87 (m, 6H); ¹³C NMR

(CDCl₃, 125 MHz) 160.1, 154.6, 153.7, 133.5,118.3,117.2, 116.0,115.6,

7.28. Synthesis of A-substituted long OPE/OPV H-mer 50 (LH-

(CHO)₄)

d

114.4, 112.6, 95.5, 84.9, 82.5, 80.5, 70.10, 70.05, 55.7, 32.35, 32.34,

30.1, 30.02, 30.0, 29.9, 29.8, 29.6, 26.5, 26.4, 23.1, 14.5; HRMS (CI)

m/z calcd for C₃₇H₅₂O₃544.3916, found 545.4039 [MþH]^þ.

Compound 49 (125 mg, 0.230 mmol), 14 (25 mg, 0.036 mmol),

Pd(PPh₃)₄(15 mg, 0.013 mmol), and CuI (8.0 mg, 0.042 mmol) were

added to Et₃N (8 mL). The solution was bubbled with N₂at rt for

5 min and then stirred at rt under N₂protection for 1 h. Afterward,

the reaction was heated to 60 ^ꢂC and stirred for 18 h under N₂

protection. After the reaction was completed as checked by TLC

analysis, the solvent was removed by rotary evaporation. The

resulting residue was diluted with CHCl₃. The mixture was ﬁltered

through a MgSO₄pad. The solution obtained was sequentially

washed with HCl (aq 10%) and brine. The organic layer was dried

over MgSO₄and concentrated under vacuum to give crude 50,

which was further puriﬁed by silica ﬂash column chromatography

(hexanes/EtOAc, 7:3) to yield compound 50 (60 mg, 0.025 mmol,

68%) as a yellow solid. Mp 103e104 ^ꢂC; IR (KBr) 2924, 2853, 2727,

7.26. Synthesis of A-substituted long OPE/OPV H-mer 47 (LH-

(CN)₄)

Compound 41 (112 mg, 0.207 mmol),14 (19 mg, 0.033 mmol), Pd

(PPh₃)₄(24 mg, 0.021 mmol), and CuI (7.8 mg, 0.041 mmol) were

added to Et₃N (6 mL). The solution was bubbled with N₂at rt for

5 min and then heated to 50 ^ꢂC under stirring and N₂protection for

17 h. After the reaction was completed as checked by TLC analysis,

the solvent was removed by rotary evaporation. The resulting res-

idue was diluted with CHCl₃. The mixture was ﬁltered through

a MgSO₄pad. The solution obtained was sequentially washed with

HCl (aq 10%) and brine. The organic layer was dried over MgSO₄and

concentrated under vacuum to give crude 47, which was further

puriﬁed by silica ﬂash column chromatography (hexanes/CH₂Cl₂,

1:1) to yield compound 47 (47 mg, 0.019 mmol, 59%) as a yellow

solid. Mp 134e135 ^ꢂC; IR (KBr) 2924, 2853, 2226, 2207, 1693, 1663,

1552, 1533, 1514, 1467, 1417, 1385 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

2207, 1703, 1600, 1560, 1513, 1496, 1467, 1417, 1386 cm^ꢀ1

;

¹H NMR

(CDCl₃, 500 MHz) 10.03 (s, 2H), 10.00 (s, 2H), 7.91 (s, 2H), 7.88 (d,

d

J¼8.5 Hz, 4H), 7.83 (d, J¼8.5 Hz, 4H), 7.81 (d, J¼17.5 Hz, 2H), 7.68 (d,

J¼9.0 Hz, 4H), 7.65 (d, J¼8.5 Hz, 4H), 7.60 (s, 4H). 7.56 (d, J¼8.5 Hz,

2H), 7.41 (d, J¼8.0 Hz, 2H), 7.28 (d, J¼18 Hz, 2H), 7.03 (s, 2H), 7.06 (s,

4H), 7.05 (s, 2H), 4.09e4.03 (m, 16H, OCH2), 1.92e1.17 (m, 128H),

d

7.92 (s, 2H), 7.81 (d, J¼15.5 Hz, 2H), 7.67e7.59 (m, 20H), 7.57 (d,

0.88e0.79 (m, 24H); ¹³C NMR (CDCl₃, 125 MHz)

d 191.53, 191.47,

J¼8.5 Hz, 2H), 7.42 (dd, J¼8.5, 1.5 Hz, 2H), 7.29 (d, J¼15.5 Hz, 2H),

7.07 (s, 4H), 7.06 (s, 2H), 7.05 (s, 2H), 4.09e4.03 (m, 16H), 1.93e1.82

(m, 12H), 1.77e1.72 (m, 4H), 1.62e1.49 (m, 12H), 1.45e1.18 (m,

154.19, 154.16, 153.93, 153.86, 139.0, 137.3, 135.61, 135.57, 132.8,

132.23, 132.20, 130.7, 130.3, 130.0, 129.9, 129.8, 129.7, 128.0, 127.5,

126.6, 123.8, 122.5, 117.4, 117.2, 117.1, 117.0, 115.1, 114.8, 113.7, 113.6,

95.3, 94.4, 94.3, 93.9, 93.1, 90.41, 90.39, 87.9, 70.1, 69.9, 69.8, 32.1,

29.9, 29.8, 29.78, 29.7, 29.6, 29.4, 26.35, 26.31, 26.1, 22.9,14.3; HRMS

(MALDI-TOF) m/z calcd for C₁₇₀H₂₁₀O₁₂2443.5822, found 2444.7471

[MþH]^þ.

100H), 0.90e0.83 (m, 24H); ¹³C NMR (CDCl₃, 125 MHz)

d 154.20,

154.17, 153.9, 153.8, 139.0, 137.3, 132.8, 132.3, 132.20. 132.18, 132.1,

130.7, 130.4, 128.61, 128.56, 128.0, 127.5, 126.6, 123.8, 122.5, 118.73,

118.69, 117.3, 117.2, 117.0, 116.9, 115.3, 115.0, 113.31, 113.28, 111.7,

111.6, 95.3, 94.0, 93.5, 93.4, 93.1, 90.8, 90.7, 87.9, 70.1, 69.9, 69.8,

32.1, 29.9, 29.8, 29.64, 29.61, 29.5, 29.4, 26.3, 26.1, 22.9, 14.3; HRMS

(MALDI-TOF) m/z calcd for C₁₇₀H₂₀₆N₄O₈2431.5836, found

2432.7026 [MþH]^þ.

7.29. Synthesis of OPE 51

Compound 12 (32 mg, 0.10 mmol), 41 (55.6 mg, 0.103 mmol),

PdCl₂(PPh₃)₂(3.6 mg, 0.0051 mmol), and CuI (1.96 mg,

0.0103 mmol) were added to Et₃N (6 mL). The solution was bubbled

with N₂at rt for 5 min and then stirred at rt under N₂protection for

3 h. After the reaction was completed as checked by TLC analysis,

the solvent was removed by rotary evaporation. The resulting res-

idue was diluted with CHCl₃. The mixture was ﬁltered through

a MgSO₄pad. The solution obtained was sequentially washed with

HCl (aq 10%) and brine. The organic layer was dried over MgSO₄and

concentrated under vacuum to give crude 51, which was further

puriﬁed by silica ﬂash column chromatography (hexanes/CH₂Cl₂,

7:3) to yield compound 51 (60 mg, 0.083 mmol, 81%) as a white

solid. Mp 82e83 ^ꢂC; IR (KBr) 2918, 2851, 2207, 1690, 1631, 1603,

7.27. Synthesis of D-substituted long OPE/OPV H-mer 48 (LH-

(OMe)₄)

Compound 46 (113 mg, 0.207 mmol), 14 (19 mg, 0.32 mmol), Pd

(PPh₃)₄(25 mg, 0.022 mmol), and CuI (12 mg, 0.063 mmol) were

added to Et₃N (8 mL). The solution was degassed by N₂bubbling at

rt for 5 min and then heated to 60 ^ꢂC under stirring and N₂pro-

tection for 18 h. After the reaction was completed as checked by TLC

analysis, the solvent was removed by rotary evaporation. The

resulting residue was diluted with CHCl₃. The mixture was ﬁltered

through a MgSO₄pad. The solution obtained was sequentially

washed with HCl (aq 10%) and brine. The organic layer was dried

over MgSO₄and concentrated under vacuum to give crude 48,

which was further puriﬁed by silica ﬂash column chromatography

(hexanes/CH₂Cl₂, 1:1) to yield compound 48 (45 mg, 0.018 mmol,

57%) as a yellow solid. Mp 98e99 ^ꢂC; IR (KBr) 2953, 2923, 2853,

1583, 1552, 1533, 1513, 1497, 1469, 1420 cm^ꢀ1

500 MHz)

;

¹H NMR (CDCl₃,

10.66 (s, 1H), 8.07 (d, J¼1.5 Hz, 1H), 7.69 (dd, J¼8.0,

d

1.5 Hz, 1H), 7.64 (d, J¼8.5 Hz, 2H), 7.60 (d, J¼8.5 Hz, 2H), 7.49 (d,

J¼8.0 Hz, 1H), 7.02 (s, 1H), 7.01 (s, 1H), 4.05e4.01 (m, 4H), 1.89e1.83

(m, 4H), 1.60e1.46 (m, 4H), 1.30e1.26 (m, 24H), 0.89e0.86 (m, 6H);

2204, 1608, 1515, 1498, 1466, 1417, 1383 cm^ꢀ1

500 MHz)

;

¹H NMR (CDCl3,

¹³C NMR (CDCl₃, 125 MHz)

d 190.9, 154.3, 154.0, 137.2, 136.8, 134.3,

d

7.91 (s, 2H), 7.81 (d, J¼17.0 Hz, 2H), 7.60 (s, 4H), 7.55 (d,

132.24, 132.20, 130.3, 128.5, 125.9, 123.4, 118.7, 116.7, 116.4, 114.1,

113.5, 111.8, 94.3, 93.8, 90.5, 90.2, 69.8, 69.6, 32.1, 29.9, 29.82, 29.76,

29.6, 29.5, 29.4, 26.3, 22.9,14.3; HRMS (CI) m/z calcd for

C₄₄H₅₂BrNO₃721.3131, found 722.3139 [MþH]^þ.

J¼8.0 Hz, 2H), 7.50 (d, J¼8.5 Hz, 4H), 7.48 (d, J¼8.5 Hz, 4H), 7.40 (d,

J¼8.5 Hz, 2H), 7.28 (d, J¼17.0 Hz, 2H), 7.06 (s, 2H), 7.05 (s, 4H), 7.03

(s, 2H), 6.89 (d, J¼8.5 Hz, 4H), 6.86 (d, J¼8.5 Hz, 4H), 4.08e4.02 (m,

16H), 3.84 (s, 1H), 3.82 (s, 1H), 1.91e1.82 (m, 12H), 1.77e1.71 (m,

4H), 1.61e1.51 (m, 12H), 1.43e1.17 (m, 100H), 0.90e0.82 (m, 24H);

7.30. Synthesis of OPE 52

¹³C NMR (CDCl₃, 125 MHz)

d 159.91, 159.87, 154.02, 153.97, 153.7,

138.9, 137.3, 133.3, 132.7, 130.7, 130.2, 128.0, 127.5, 126.6, 123.8,

122.5, 117.24, 117.20, 117.1, 115.8, 115.2, 115.0, 114.20, 114.18, 113.7,

113.5, 95.5, 95.4, 94.7, 93.3, 88.0, 84.92, 84.89, 70.04, 69.95, 69.92,

69.9, 55.5, 55.47, 32.1, 29.9, 29.8, 29.7, 29.68, 29.65, 29.63, 29.58,

29.4, 22.9, 14.3; HRMS (MALDI-TOF) m/z calcd for C₁₇₀H₂₁₈O₁₂

2451.6448, found 2453.0938 [MþH]^þ.

Compound 51 (61 mg, 0.084 mmol), 46(142 mg, 0.261 mmol), Pd

(PPh₃)₄(15 mg, 0.13 mmol), and CuI (5.0 mg, 0.026 mmol) were

added to Et₃N (10 mL). The solution was bubbled with N₂at rt for

5 min, stirred at rt for 3 h, and then heated to 60 ^ꢂC under stirring

and N₂protection for 4 h. After the reaction was completed as

checked by TLC analysis, the solvent was removed by rotary

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

141

evaporation. The resulting residue was diluted with CHCl₃. The

mixture was ﬁltered through a MgSO₄pad. The solution obtained

was sequentially washed with HCl (aq 10%) and brine. The organic

layer was dried over MgSO₄and concentrated under vacuum to

give crude 52, which was further puriﬁed by silica ﬂash column

chromatography (hexanes/CH₂Cl₂, 3:2) to yield compound 52

(80 mg, 0.067 mmol, 80%) as a yellow solid. Mp 128e129 ^ꢂC; IR

(KBr) 2922, 2851, 2224, 2208, 1696, 1649, 1604, 1557, 1515, 1486,

2H), 7.60 (d, J¼8.0 Hz, 2H), 7.60 (d, J¼8.0 Hz, 1H), 7.48 (d, J¼8.5 Hz,

2H), 7.02 (s, 1H), 7.01 (br, 3H), 6.89 (d, J¼8.5 Hz, 2H), 4.05e4.03

(m, 4H), 3.83 (s, 3H), 1.90e1.82 (m, 8H), 1.58e1.47 (m, 8H),

1.39e1.25 (m, 48H), 0.89e0.85 (m, 12H); ¹³C NMR (CDCl₃, 125 MHz)

d

191.7, 160.0, 154.5, 154.1, 153.9, 153.6, 136.2, 136.0, 133.3, 133.0,

132.3, 132.2, 130.4, 128.6, 126.8, 123.9, 118.8, 117.1, 117.06, 117.0,

116.3, 116.0, 115.7, 114.6, 114.2, 113.5, 112.1, 111.7, 96.0, 95.4, 94.2,

93.5, 90.7, 90.4, 89.0, 84.8, 70.00, 69.95, 69.8, 69.6, 55.5, 32.1, 29.9,

29.8, 29.79, 29.7, 29.6, 29.5, 26.3, 22.9,14.3; HRMS (MALDI-TOF) m/z

calcd for C₈₁H₁₀₃NO₆1185.7785, found 1186.0105 [MþH]^þ.

1467, 1417, 1387 cm^ꢀ^{1 1}H NMR (CDCl₃, 500 MHz)

; d 10.73 (s, 1H),

8.11 (d, J¼2.0 Hz, 1H), 7.70 (dd, J¼8.5, 2.0 Hz, 1H), 7.66 (d, J¼8.5 Hz,

2H), 7.62 (d, J¼8.5 Hz, 2H), 7.61 (d, J¼8.5 Hz, 1H), 7.49 (d, J¼8.5 Hz,

2H), 7.05 (s, 1H), 7.03 (s, 1H), 7.022 (s, 1H), 7.016 (s, 1H), 6.70 (d,

J¼8.5 Hz, 2H), 4.07e4.04 (m, 4H), 4.07e4.04 (m, 8H), 3.85 (s, 3H),

1.91e1.84 (m, 8H),1.56e1.48 (m, 8H),1.40e1.27 (m, 48H), 0.91e0.86

7.33. Synthesis of D-A substituted long OPE/OPV H-mer 55

(LH-1,3-(CN)₂-2,4-(OMe)₂)

(m, 12H); ¹³C NMR (CDCl₃, 125 MHz)

d

191.5, 159.9, 154.3, 154.1,

To an oven-dried round-bottom ﬂask protected under N₂atmo-

sphere were added compound 13 (12.8 mg, 0.337 mmol), NaH

(2.02 mg, 0.0843 mmol), and dry THF (8 mL). Upon gentle heating at

50 ^ꢂC, the solution gradually turned into a pink color. Aldehyde 52

(80 mg, 0.067 mmol) dissolved in THF (5 mL) was added in small

portions overa period of 1 h through a syringe. The reactionwas kept

under stirring and heating for another 2 h before workup. The small

excess NaH was carefully quenched with H₂O and the mixture was

extracted with CHCl₃three times. The organic layer was washed

with brine, dried over MgSO₄, and concentrated to form a yellow

solid. The yellow solid was puriﬁed by silica ﬂash column chroma-

tography (hexanes/CH₂Cl₂, 1:1) to give compound 55 (35 mg,

0.014 mmol, 21%) as a yellow solid. Mp 126e127 ^ꢂC; IR (KBr) 2923,

154.0, 153.6, 136.2, 136.1, 133.3, 133.0, 132.22, 132.19, 130.3, 128.5,

126.2, 124.5, 118.7, 117.2, 116.9, 116.7, 116.4, 115.7, 115.5, 114.2, 114.0,

113.8, 112.9, 111.7, 95.6, 94.8, 93.7, 93.4, 91.2, 90.7, 89.7, 84.8, 69.9,

69.8, 69.6, 55.5, 32.1, 29.9, 29.83, 29.78, 29.7, 29.6, 29.56, 29.53,

29.5, 26.3, 22.9, 14.3; HRMS (MALDI-TOF) m/z calcd for C₈₁H₁₀₃NO₆

1185.7785, found 1186.0105 [MþH]^þ.

7.31. Synthesis of OPE 53

Compound 12 (32.0 mg, 0.103 mmol), 46 (55.6 mg, 0.103 mmol),

PdCl₂(PPh₃)₂(3.6 mg, 0.0051 mmol), and CuI (1.96 mg,

0.0103 mmol) were added to Et₃N (8 mL). The solution was bubbled

with N₂at rt for 5 min and then stirred at rt under N₂protection for

8 h. After the reaction was completed as checked by TLC analysis,

the solvent was removed by rotary evaporation. The resulting res-

idue was diluted with CHCl₃. The mixture was ﬁltered through

a MgSO₄pad. The solution obtained was sequentially washed with

HCl (aq 10%) and brine. The organic layer was dried over MgSO₄and

concentrated under vacuum to give crude 53, which was further

puriﬁed by silica ﬂash column chromatography (hexanes/CH₂Cl₂,

7:3) to yield compound 53 (21 mg, 0.029 mmol, 28%) as a white

solid. Mp 75e76 ^ꢂC; IR (KBr) 2920, 2872, 2852, 2203, 1692, 1600,

1581, 1568, 1514, 1499, 1466, 1418 cm^ꢀ1; ¹H NMR (CDCl₃, 500 MHz)

2853, 2227, 2206,1634,1605,1557,1514,1496,1468,1417,1393 cm^ꢀ1

¹H NMR (CDCl₃, 500 MHz)

;

d

7.91 (s, 2H), 7.80 (d, J¼16.5 Hz, 2H), 7.62

(d, J¼8.0 Hz, 4H), 7.60 (s, 4H), 7.58 (d, J¼8.0 Hz, 4H), 7.55 (d, J¼7.0 Hz,

2H), 7.50 (d, J¼8.5 Hz, 4H), 7.43 (d, J¼7.0 Hz, 2H), 7.28 (d, J¼16.5 Hz,

2H), 7.06 (s, 2H), 7.05 (s, 2H), 7.041 (s, 2H), 7.036 (s, 2H), 6.90 (d,

J¼8.5 Hz, 4H), 4.08e4.02 (m, 16H), 3.85 (s, 6H), 1.90e1.82 (m, 12H),

1.77e1.71 (m, 4H), 1.61e1.49 (m, 12H), 1.42e1.17 (m, 100H),

0.90e0.82 (m, 24H); ¹³C NMR (CDCl₃,125 MHz)

d 159.9,154.2,154.0,

153.8, 153.7, 139.0, 137.3, 133.3, 132.8, 132.22, 132.16, 130.8, 130.3,

128.6, 128.0, 127.5, 126.6, 124.1, 122.2, 118.7, 117.4, 117.3, 117.1, 116.9,

115.8,115.4,115.1,114.2,113.4,113.2,111.6, 95.5, 94.6, 94.1, 93.5, 92.9,

90.8, 88.3, 84.8, 70.2, 70.0, 69.9, 69.8, 55.5, 32.1, 29.9, 29.8, 29.69,

29.66, 29.64, 29.58, 29.4, 26.3, 26.1, 22.9, 14.3; HRMS (MALDI-TOF)

m/z calcd for C₁₇₀H₂₁₂N₂O₁₀2441.6142, found 2442.9568 [MþH]^þ.

d

10.68 (s,1H), 8.08 (d, J¼1.5 Hz,1H), 7.70 (dd, J¼8.5,1.5 Hz,1H), 7.50

(d, J¼8.5 Hz, 2H), 7.49 (d, J¼8.5 Hz, 2H), 7.02 (s,1H), 7.01 (s, 1H), 6.90

(d, J¼8.5 Hz, 1H), 4.06e4.02 (m, 4H), 3.85 (s, 3H), 1.90e1.84 (m, 4H),

1.59e1.47 (m, 4H), 1.42e1.27 (m, 24H), 0.90e0.87 (m, 6H); ¹³C NMR

(CDCl₃, 125 MHz)

d

191.3, 160.2, 154.7, 153.8, 137.4, 137.0, 134.5,

7.34. Synthesis of D-A substituted long OPE/OPV H-mer 56

133.5, 130.5, 126.4, 123.3, 117.1, 116.5, 116.3, 115.8, 114.4, 112.1, 96.2,

95.0, 89.7, 85.0, 70.2, 69.7, 55.7, 32.3, 30.1, 30.05, 30.01, 30.0, 29.9,

29.8, 29.76, 29.70, 26.5, 23.1, 14.5; HRMS (CI) m/z calcd for

C₄₄H₅₅BrO₄726.3284, found 727.3430 [MþH]^þ.

(LH-2,4-(CN)₂-1,3-(OMe)₂)

To an oven-dried round-bottom ﬂask protected under a N₂at-

mosphere were added compound 13 (2.88 mg, 0.00761 mmol), NaH

(0.36 mg, 0.0152 mmol), and dry THF (6 mL). Upon gentle heating at

50 ^ꢂC, the solution gradually turned into a pink color. Aldehyde 54

(18 mg, 0.015 mmol) dissolved in THF (5 mL) was added in small

portions over a period of 1 h through a syringe. The reaction was

kept under stirring and heating for another 4 h before workup. The

small excess NaH was carefully quenched with H₂O and the mixture

was extracted three times with CHCl₃. The organic layer was

washed with brine, dried over MgSO₄, and concentrated to form

a yellow solid. The yellow solid was puriﬁed by silica ﬂash column

chromatography (hexanes/CH₂Cl₂, 1:1) to give compound 56

(11 mg, 0.0045 mmol, 59%) as a yellow solid. Mp 121e122 ^ꢂC; IR

(KBr) 2924, 2854, 2226, 2202, 1649, 1635, 1558, 1540, 1514, 1469,

7.32. Synthesis of OPE 54

Compound 53 (21 mg, 0.029 mmol), 41 (31.2 mg, 0.0578 mmol),

PdCl₂(PPh₃)₂(2.0 mg, 0.0029 mmol), and CuI (1.1 mg, 0.0058 mmol)

were added to Et₃N (6 mL). The solution was bubbled with N₂at rt

for 5 min and then stirred for 3 h at rt and then heated to 60 ^ꢂC

under stirring and N₂protection for 5 h. After the reaction was

completed as checked by TLC analysis, the solvent was removed by

rotary evaporation. The resulting residue was diluted with chloro-

form. The mixture was ﬁltered through a MgSO₄pad. The solution

obtained was sequentially washed with HCl (aq 10%) and brine. The

organic layer was dried over MgSO4 and concentrated under vac-

uum to give crude 54, which was further puriﬁed by silica ﬂash

column chromatography (hexanes/CH₂Cl₂, 13:7) to yield compound

54 (24 mg, 0.020 mmol, 71%) as a yellow solid. Mp 98e99 ^ꢂC; IR

(KBr) 2954, 2924, 2852, 2204, 1694, 1632, 1553, 1535, 1516, 1484,

1418, 1385 cm^ꢀ^{1 1}H NMR (CDCl₃, 500 MHz)

; d 7.91 (s, 2H), 7.80 (d,

J¼15.5 Hz, 2H), 7.66 (d, J¼8.5 Hz, 4H), 7.62 (d, J¼8.5 Hz, 4H), 7.60 (s,

4H), 7.55 (d, J¼8.0 Hz, 2H), 7.48 (d, J¼8.5 Hz, 4H), 7.41 (d, J¼8.0 Hz,

2H), 7.28 (d, J¼15.5 Hz, 2H), 7.07 (s, 2H), 7.06 (s, 2H), 7.04 (s, 4H),

6.87 (d, J¼8.5 Hz, 4H), 4.09e4.02 (m, 16H), 3.83 (s, 6H), 1.91e1.83

(m, 12H), 1.76e1.71 (m, 4H), 1.61e1.51 (m, 12H), 1.44e1.17 (m,

; d 10.73 (s, 1H),

1468, 1453, 1416 cm^ꢀ^{1 1}H NMR (CDCl₃, 500 MHz)

8.09 (d, J¼1.0 Hz, 1H), 7.68 (dd, J¼8.0, 1.0 Hz, 1H), 7.64 (d, J¼8.0 Hz,

100H), 0.90e0.82 (m, 24H); ¹³C NMR (CDCl₃, 125 MHz)

d 159.9,

142

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

154.2, 154.0, 153.8, 153.7, 139.0, 137.3, 133.3, 132.8, 132.3, 132.2,

130.7, 130.3, 128.7, 128.1, 127.5, 126.6, 123.5, 122.8, 118.8, 117.22,

117.19, 117.0, 115.8, 115.24, 115.17, 114.2, 113.6, 113.2, 111.6, 95.55,

95.47, 93.5, 93.4, 93.2, 90.8, 87.7, 84.9, 70.0, 69.96, 69.8, 55.5, 32.1,

29.9, 29.83, 29.79, 29.71, 29.66, 29.63, 29.58, 29.4, 26.3, 26.2, 22.9,

14.3; HRMS (MALDI-TOF) m/z calcd for C₁₇₀H₂₁₂N₂O₁₀2441.6142,

found 2442.6895 [MþH]^þ.

Grant program and Memorial University of Newfoundland.

N.Z. thanks NSERC (PGS-D) for scholarship support.

Supplementary data

NMR spectroscopic data for all new compounds synthesized.

Supplementary data associated with this article can be found in the

online version, at doi:10.1016/j.tet.2010.11.012. These data include

MOL ﬁles and InChIKeys of the most important compounds de-

scribed in this article.

7.35. Synthesis of Z-shaped OPE/OPV 57

Compound 14 (35.5 mg, 0.0652 mmol), 46 (22.5 mg,

0.0326 mmol), PdCl₂(PPh₃)₂(2.3 mg, 0.0033 mmol), and CuI

(1.2 mg, 0.0065 mmol) were added to Et₃N (8 mL). The solution was

bubbled with N₂at rt for 5 min and then was stirred at rt under N₂

protection for 7 h. After the reaction was completed as checked by

TLC analysis, the solvent was removed by rotary evaporation. The

resulting residue was diluted with CHCl₃. The mixture was ﬁltered

through a MgSO₄pad. The solution obtained was sequentially

washed with HCl (aq 10%) and brine. The organic layer was dried

over MgSO₄and concentrated under vacuum to give crude 57,

which was further puriﬁed by silica ﬂash column chromatography

(hexanes/CH₂Cl₂, 7:3) to yield compound 57 (24 mg, 0.016 mmol,

48%) as a yellow solid. Mp 138e139 ^ꢂC; IR (KBr) 2959, 2924, 2853,

2206, 1636, 1620, 1576, 1559, 1540, 1514, 1459, 1417, 1384 cm^ꢀ1; ¹H

References and notes

1. Tour, J. M. Acc. Chem. Res. 2000, 33, 791e804.

€

2. Mullen, K.; Wegner, G. Electronic Materials: The Oligomer Approach; Wiley-VCH:

Weinheim; New York, NY, 1998.

ꢀ

3. Bredas, J. L. Conjugated Oligomers, Polymers, and Dendrimers: From Polyacetylene

to DNA; Bruxelles: Paris, 1999.

4. Martin, R. E.; Diederich, F. Angew. Chem., Int. Ed. 1999, 38, 1350e1377.

€

5. Grimsdale, A. C.; Mullen, K. Angew. Chem., Int. Ed. 2005, 44, 5592e5629.

6. Tour, J. M. Chem. Rev. 1996, 96, 537e554.

7. Meier, H. Angew. Chem., Int. Ed. 2005, 44, 2482e2506.

8. Thomas, S. W.; Joly, G. D.; Swager, T. M. Chem. Rev. 2007, 107, 1339e1386.

€

9. Muller, T. J. J.; Bunz, U. H. F. Functional Organic Materials: Syntheses, Strategies

and Applications; Wiley-VCH: Weinheim, 2007.

10. Bunz, U. H. F. Chem. Rev. 2000, 100, 1605e1644.

11. Roncali, J. Acc. Chem. Res. 2000, 33, 147e156.

12. Design and Synthesis of Conjugated Polymers; Leclerc, M., Morin, J.-F., Eds.;

NMR (CDCl₃, 500 MHz)

d

7.86 (d, J¼2.0 Hz, 2H), 7.74 (d, J¼16 Hz,

2H), 7.58 (s, 4H), 7.48 (d, J¼8.5 Hz, 4H), 7.42 (d, J¼8.5 Hz, 2H), 7.36

(dd, J¼16.0, 2 Hz, 2H), 7.21 (d, J¼16.0 Hz, 2H), 7.05 (s, 2H), 7.02 (s,

2H), 6.87 (d, J¼8.5 Hz, 4H), 4.02 (t, J¼6.5 Hz, 8H), 3.83 (s, 6H),

1.87e1.81 (m, 4H), 1.74e1.69 (m, 4H), 1.56e1.50 (m, 4H), 1.38e1.16

(m, 52H), 0.87 (t, J¼6.0 Hz, 6H), 0.85 (t, J¼6.0 Hz, 6H); ¹³C NMR

Wiley-VCH: Weinheim, 2010.

13. Diederich, F.; Gobbi, L. In Carbon Rich Compounds II, Macrocyclic Oligoacetylenes

and Other Linearly Conjugated Systems; de Meijere, A., Ed.; Springer: Berlin,

1999; pp 43e79.

14. Opsitnick, E.; Lee, D. Chem.dEur. J. 2007, 13, 7040e7049.

15. Jiang, X.; Bollinger, J. C.; Lee, D. J. Am. Chem. Soc. 2006, 128, 11732e11733.

16. Tykwinski, R. R.; Zhao, Y. Synlett 2002, 2002, 1939e1953.

17. Kivala, M.; Mitzel, F.; Boudon, C.; Gisselbrecht, J. P.; Seiler, P.; Gross, M.;

Diederich, F. Chem.dAsian J. 2006, 1, 479e489.

18. He, F.; Tian, L. L.; Tian, X. Y.; Xu, H.; Wang, Y. H.; Xie, W. J.; Hanif, M.; Xia, J. L.;

Shen, F. Z.; Yang, B.; Li, F.; Ma, Y. G.; Yang, Y. Q.; Shen, J. C. Adv. Funct. Mater.

2007, 17, 1551e1557.

19. Pina, J.; Seixas de Melo, J.; Burrows, H. D.; Bilge, A.; Farrell, T.; Forster, M.;

Scherf, U. J. Phys. Chem. B 2006, 110, 15100e15106.

(CDCl₃, 125 MHz)

d 160.1, 154.2, 153.9, 140.9, 137.4, 134.2, 133.5,

131.3, 130.6, 128.1, 127.8, 126.3, 123.1, 121.9, 117.37, 117.35, 116.0,

115.5, 114.4, 113.7, 95.7, 92.9, 92.7, 85.1, 70.23, 70.18, 55.7, 32.33,

32.31, 30.1, 30.05, 30.03, 30.0, 29.91, 29.85, 29.8, 29.6, 26.6, 26.4,

23.1, 14.5; MALDI-TOF MS (þeV) m/z calcd for C₉₆H₁₁₆Br₂O₆

1522.7152, found 1523.7930 [MþH]^þ.

20. Bilge, A.; Zen, A.; Forster, M.; Li, H.; Galbrecht, F.; Nehls, B. S.; Farrell, T.; Neher,

D.; Scherf, U. J. Mater. Chem. 2006, 16, 3177e3182.

7.36. Synthesis of D-A substituted long OPE/OPV H-mer 58

(LH-1,3-(OMe)₂-2,4-(CHO)₂)

21. Zen, A.; Pingel, P.; Neher, D.; Scherf, U. Phys. Stat. Sol. 2008, 205, 440e448.

22. Sun, X. B.; Liu, Y. Q.; Chen, S. Y.; Qiu, W. F.; Yu, G.; Ma, Y. Q.; Qi, T.; Zhang, H. J.;

Xu, X. J.; Zhu, D. B. Adv. Funct. Mater. 2006, 16, 917e925.

23. Zen, A.; Bilge, A.; Galbrecht, F.; Alle, R.; Meerholz, K.; Grenzer, J.; Neher, D.;

Scherf, U.; Farrell, T. J. Am. Chem. Soc. 2006, 128, 3914e3915.

24. Al Ouahabi, A.; Baxter, P. N. W.; Gisselbrecht, J.-P.; De Cian, A.; Brelot, L.; Kyritsakas-

Gruber, N. J. Org. Chem. 2009, 74, 4675e4689.

Compound 57 (24 mg, 0.016 mmol), 49 (34 mg, 0.063 mmol),

PdCl₂(PPh₃)₂(1.1 mg, 0.0016 mmol), and CuI (0.59 mg,

0.0031 mmol) were added to Et₃N (6 mL). The solution was bubbled

with N₂at rt for 5 min and then stirred at 65 ^ꢂC under N₂protection

for 12 h. After the reaction was completed as checked by TLC

analysis, the solvent was removed by rotary evaporation. The

resulting residue was diluted with CHCl₃. The mixture was ﬁltered

through a MgSO₄pad. The solution obtained was sequentially

washed with HCl (aq 10%) and brine. The organic layer was dried

over MgSO₄and concentrated under vacuum to give crude 58,

which was further puriﬁed by silica ﬂash column chromatography

(hexanes/CH₂Cl₂, 1:4) to yield compound 58 (23 mg, 0.0094 mmol,

61%) as a yellow solid. Mp 98e99 ^ꢂC; ¹H NMR (CDCl₃, 500 MHz)

25. Kanibolotsky, A. L.; Berridge, R.; Skabara, P. J.; Perepichka, I. F.; Bradley, D. D. C.;

Koeberg, M. J. Am. Chem. Soc. 2004, 126, 13695e13702.

26. Zhang,J.;Yang,Y.;He, C.;He, Y.;Zhao, G.;Li, Y. Macromolecules2009, 42, 7619e7622.

27. Zen, A.; Pingel, P.; Jaiser, F.; Neher, D.; Grenzer, J.; Zhuang, W.; Rabe, J. P.; Bilge,

A.; Galbrecht, F.; Nehls, B. S.; Farrell, T.; Scherf, U.; Abellon, R. D.; Grozema, F. C.;

Siebbeles, L. D. A. Chem. Mater. 2007, 19, 1267e1276.

€

28. Mossinger, D.; Hornung, J.; Lei, S.; De Feyter, S.; Hoger, S. Angew. Chem., Int. Ed.

2007, 46, 6802e6806.

29. Spitler, E. L.; Johnson, C. A.; Haley, M. M. Chem. Rev. 2006, 106, 5344e5386.

30. Godoy, J.; Vives, G.; Tour, J. M. Org. Lett. 2010, 12, 1464e1467.

31. Vives, G.; Kang, J.; Kelly, K. F.; Tour, J. M. Org. Lett. 2009, 11, 5602e5605.

32. Sasaki, T.; Osgood, A. J.; Alemany, L. B.; Kelly, K. F.; Tour, J. M. Org. Lett. 2007, 10,

229e232.

33. Sasaki, T.; Tour, J. M. Org. Lett. 2008, 10, 897e900.

34. Khatua, S.; Guerrero, J. M.; Claytor, K.; Vives, G.; Kolomeisky, A. B.; Tour, J. M.;

d

10.04 (s, 2H), 7.91 (s, 2H), 7.88 (d, J¼8.5 Hz, 4H), 7.81 (d, J¼15.0 Hz,

2H), 7.69 (d, J¼8.5 Hz, 4H), 7.60 (s, 4H), 7.55 (d, J¼8.0 Hz, 2H), 7.48

(d, J¼8.0 Hz, 4H), 7.41 (d, J¼8 Hz, 2H), 7.28 (d, J¼15.0 Hz, 2H), 7.07 (s,

2H), 7.06 (s, 4H), 7.04 (s, 2H), 6.87 (d, J¼8.5 Hz, 4H), 4.09e4.02 (m,

16H), 3.83 (s, 6H), 1.92e1.17 (m, 128H), 0.89e0.82 (m, 24H).

Meaningful ¹³C NMR spectrum could not be obtained due to limited

concentration; HRMS (MALDI-TOF) m/z calcd for C₁₇₀H₂₁₄O₁₂

2447.6135, found 2448.8347 [MþH]^þ.

Link, S. ACS Nano 2009, 3, 351e356.

35. Vives, G.; Tour, J. M. Acc. Chem. Res. 2009, 42, 473e487.

36. Shirai, Y.; Osgood, A. J.; Zhao, Y.; Kelly, K. F.; Tour, J. M. Nano Lett. 2005, 5,

2330e2334.

37. Shirai, Y.; Osgood, A. J.; Zhao, Y.; Yao, Y.; Saudan, L.; Yang, H.; Yu-Hung, C.;

Alemany, L. B.; Sasaki, T.; Morin, J.-F.; Guerrero, J. M.; Kelly, K. F.; Tour, J. M. J. Am.

Chem. Soc. 2006, 128, 4854e4864.

38. Miao, Q.; Chi, X.; Xiao, S.; Zeis, R.; Lefenfeld, M.; Siegrist, T.; Steigerwald, M. L.;

Nuckolls, C. J. Am. Chem. Soc. 2006, 128, 1340e1345.

39. Klare, J. E.; Tulevski, G. S.; Sugo, K.; de Picciotto, A.; White, K. A.; Nuckolls, C. J.

Am. Chem. Soc. 2003, 125, 6030e6031.

Acknowledgements

ꢀ

€

40. Grunder, S.; Huber, R.; Horhoiu, V.; Gonzalez, M. T.; Schonenberger, C.; Calame,

M.; Mayor, M. J. Org. Chem. 2007, 72, 8337e8344.

41. Florio, G. M.; Klare, J. E.; Pasamba, M. O.; Werblowsky, T. L.; Hyers, M.; Berne, B.

J.; Hybertsen, M. S.; Nuckolls, C.; Flynn, G. W. Langmuir 2006, 22, 10003e10008.

This work was supported by the Natural Sciences and Engi-

neering Research Council of Canada (NSERC) through the Discovery

N. Zhou et al. / Tetrahedron 67 (2011) 125e143

143

42. Pham, P.-T. T.; Xia, Y.; Frisbie, C. D.; Bader, M. M. J. Phys. Chem. C 2008, 112,

7968e7971.

67. Nicolas, Y.; Blanchard, P.; Levillain, E.; Allain, M.; Mercier, N.; Roncali, J. Org. Lett.

2003, 6, 273e276.

43. Jiang, X.; Gyu Park, B.; Riddle, J. A.; June Zhang, B.; Pink, M.; Lee, D. Chem.

68. Zhou, X.-H.; Yan, J.-C.; Pei, J. Org. Lett. 2003, 5, 3543e3546.

69. Ma, Z.; Wang, Y.-Y.; Wang, P.; Huang, W.; Li, Y.-B.; Lei, S.-B.; Yang, Y.-L.; Fan,

X.-L.; Wang, C. ACS Nano 2007, 1, 160e167.

70. Yang, J.-S.; Huang, H.-H.; Ho, J.-H. J. Phys. Chem. B 2008, 112, 8871e8878.

71. Tang, Z.-M.; Lei, T.; Wang, J.-L.; Ma, Y.; Pei, J. J. Org. Chem. 2010, 75, 3644e3655.

72. Yang, J.-S.; Huang, H.-H.; Liu, Y.-H.; Peng, S.-M. Org. Lett. 2009, 11, 4942e4945.

73. Justin Thomas, K. R.; Lin, J. T.; Tao, Y.-T.; Ko, C.-W. Chem. Mater. 2002, 14,

1354e1361.

Commun. 2008, 6028e6030.

44. Sonntag, M.; Kreger, K.; Hanft, D.; Strohriegl, P.; Setayesh, S.; de Leeuw,

D. Chem. Mater. 2005, 17, 3031e3039.

45. Diring, S. p.; Puntoriero, F.; Nastasi, F.; Campagna, S.; Ziessel, R. J. Am. Chem. Soc.

2009, 131, 6108e6110.

46. Brombosz, S. M.; Zucchero, A. J.; Phillips, R. L.; Vazquez, D.; Wilson, A.; Bunz,

U. H. F. Org. Lett. 2007, 9, 4519e4522.

47. Zucchero, A. J.; Wilson, J. N.; Bunz, U. H. F. J. Am. Chem. Soc. 2006, 128,

11872e11881.

74. Yang, J.-S.; Lee, Y.-R.; Yan, J.-L.; Lu, M.-C. Org. Lett. 2006, 8, 5813e5816.

75. Cui, Y.; Wang, S. J. Org. Chem. 2006, 71, 6485e6496.

76. Taerum, T.; Lukoyanova, O.; Wylie, R. G.; Perepichka, D. F. Org. Lett. 2009, 11,

3230e3233.

77. Jia, H.-P.; Liu, S.-X.; Sanguinet, L.; Levillain, E.; Decurtins, S. J. Org. Chem. 2009,

74, 5727e5729.

48. Zucchero, A. J.; McGrier, P. L.; Bunz, U. H. F. Acc. Chem. Res. 2010, 43, 397e408.

49. Tolosa, J.; Zucchero, A. J.; Bunz, U. H. F. J. Am. Chem. Soc. 2008, 130, 6498e6506.

50. Wilson, J. N.; Bunz, U. H. F. J. Am. Chem. Soc. 2005, 127, 4124e4125.

51. Marsden, J. A.; Miller, J. J.; Shirtcliff, L. D.; Haley, M. M. J. Am. Chem. Soc. 2005,

127, 2464e2476.

78. Zhang, W.-B.; Jin, W.-H.; Zhou, X.-H.; Pei, J. Tetrahedron 2007, 63, 2907e2914.

79. Sharma, A.; Sharma, N.; Kumar, R.; Shard, A.; Sinha, A. K. Chem. Commun. 2010,

46, 3283e3285.

52. McGrier, P. L.; Solntsev, K. M.; Schonhaber, J.; Brombosz, S. M.; Tolbert, L. M.;

Bunz, U. H. F. Chem. Commun. 2007, 2127e2129.

53. Sùrensen, J. K.; Vestergaard, M.; Kadziola, A.; Kilsa, K.; Nielsen, M. B. Org. Lett.

ꢁ

ꢀ

80. Arrigoni, C.; Schull, G.; Blecger, D.; Douillard, L.; Fiorini-Debuisschert, C. l.;

2006, 8, 1173e1176.

Mathevet, F.; Kreher, D.; Attias, A.-J.; Charra, F. J. Phys. Chem. Lett. 2009, 1,

190e194.

81. Shirai, Y.; Zhao, Y.; Cheng, L.; Tour, J. M. Org. Lett. 2004, 6, 2129e2132.

82. Zhou, N.; Zhao, Y. J. Org. Chem. 2010, 75, 1498e1516.

83. Zhao, Y.; Shirai, Y.; Slepkov, A. D.; Cheng, L.; Alemany, L. B.; Sasaki, T.; Hegmann,

F. A.; Tour, J. M. Chem.dEur. J. 2005, 11, 3643e3658.

54. Guthrie, D. A.; Tovar, J. D. Org. Lett. 2008, 10, 4323e4326.

55. Dalton, G. T.; Cifuentes, M. P.; Petrie, S.; Stranger, R.; Humphrey, M. G.; Samoc,

M. J. Am. Chem. Soc. 2007, 129, 11882e11883.

56. Zhang, H. C.; Guo, E. Q.; Zhang, Y. L.; Ren, P. H.; Yang, W. J. Chem. Mater. 2009, 21,

5125e5135.

57. Tolosa, J.; Solntsev, K. M.; Tolbert, L. M.; Bunz, U. H. F. J. Org. Chem. 2009, 75,

523e534.

58. Grunder, S.; Huber, R.; Wu, S.; Schonenberger, C.; Calame, M.; Mayor, M. Eur. J.

Org. Chem. 2010, 2010, 833e845.

59. Cui, W.; Fu, Y.; Qu, Y.; Tian, H.; Zhang, J.; Xie, Z.; Geng, Y.; Wang, F. Chem.dAsian

J. 2010, 5, 932e940.

84. Chandra, K. L.; Zhang, S.; Gorman, C. B. Tetrahedron 2007, 63, 7120e7132.

85. Zhou, N.; Wang, L.; Thompson, D. W.; Zhao, Y. Org. Lett. 2008, 10, 3001e3004.

86. Kong, Q.; Zhu, D.; Quan, Y.; Chen, Q.; Ding, J.; Lu, J.; Tao, Y. Chem. Mater. 2007, 19,

3309e3318.

€

ꢀ

87. Nierengarten, J.-F.; Zhang, S.; Gegout, A.; Urbani, M.; Armaroli, N.; Marconi, G.;

Rio, Y. J. Org. Chem. 2005, 70, 7550e7557.

60. Sun, J.; Cheng, J. G.; Zhu, W. Q.; Ren, S. J.; Zhong, H. L.; Zeng, D. L.; Du, J. P.; Xu,

E. J.; Liu, Y. C.; Fang, Q. J. Polym. Sci., Part A: Polym. Chem. 2008, 46, 5616e5625.

61. Zhou, N.; Wang, L.; Thompson, D. W.; Zhao, Y. Tetrahedron Lett. 2007, 48,

3563e3567.

88. Le, Z.-G.; Chen, Z.-C.; Hu, Y.; Zheng, Q.-G. Synthesis 2004, 2004, 2809e2812.

89. Frahn, J.; Schluter, A. D. Synthesis 1997, 1997, 1301e1304.

90. Cade, I.; Long, N. J.; White, A. J. P.; Williams, D. J. J. Organomet. Chem. 2006, 691,

1389e1401.

€

62. Winter, A.; Friebe, C.; Hager, M. D.; Schubert, U. S. Eur. J. Org. Chem. 2009, 2009,

801e809.

91. Lv, X.; Mao, J.; Liu, Y.; Huang, Y.; Ma, Y.; Yu, A.; Yin, S.; Chen, Y. Macromolecules

2008, 41, 501e503.

63. Cherioux, F.; Audebert, P.; Hapiot, P. Chem. Mater. 1998, 10, 1984e1989.

64. Kannan, R.; He, G. S.; Lin, T.-C.; Prasad, P. N.; Vaia, R. A.; Tan, L.-S. Chem. Mater.

2003, 16, 185e194.

65. Omer, K. M.; Ku, S.-Y.; Chen, Y.-C.; Wong, K.-T.; Bard, A. J. J. Am. Chem. Soc. 2010,

132, 10944e10952.

92. Ranganathan, A.; Heisen, B. C.; Dix, I.; Meyer, F. Chem. Commun. 2007,

3637e3639.

93. Wolska, J.; Mieczkowski, J.; Pociecha, D.; Buathong, S. w.; Donnio, B.; Guillon,

D.; Gorecka, E. Macromolecules 2009, 42, 6375e6384.

€

94. Binstead, R.A.; Zuberbuhler, A.D. Spectrum Software Associates: Chapel Hill,

66. Wang, J.-L.; Tang, Z.-M.; Xiao, Q.; Ma, Y.; Pei, J. Org. Lett. 2009, 11, 863e866.

NC, 1993e1997.

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OPE/OPV H-mers: Synthesis, electronic properties, and spectroscopic responses to binding with transition metal ions

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