Synthesis and stability studies of conformationally locked 4-(diarylamino)aryl- and 4-(dialkylamino)phenyl-substituted second-order nonlinear optical polyene chromophores

Article abstract of DOI:10.1039/b208024a

A series of chromophores with high second-order nonlinearities has been synthesized; the chromphores consist of triarylamine or dialkylarylamine donors linked by a conformationally locked polyene bridge to a dicyanomethylidene acceptor. The use of bridges

Full text of DOI:10.1039/b208024a

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Synthesis and stability studies of conformationally locked
4-(diarylamino)aryl- and 4-(dialkylamino)phenyl-substituted
second-order nonlinear optical polyene chromophores
Katrin Staub,a Galina A. Levina,a Stephen Barlow,*a,b Tony C. Kowalczyk,c Hilary
1S. Lackritz,c Marguerite Barzoukas,d Alain Fortd and Seth R. Marder*a,b,e
aBeckman Institute, California Institute of Technology, Pasadena, CA 91125, USA
bDepartment of Chemistry, University of Arizona Tucson, AZ 85721, USA.
E-mail: sbarlow@email.arizona.edu
cGemfire Research, 2440 Embarcadero Way, Palo Alto, CA 94303, USA
dInstitut de Physique et Chimie Mate´riaux de Strasbourg, Groupe d’Optique nonline´aire et
d’Optoe´lectronique (UM 046 CNRS), rue du Loess 23, F-67037 Strasbourg Cedex, France
eOptical Sciences Center, University of Arizona Tucson, AZ 85721, USA
Received 12th August 2002, Accepted 3rd February 2003
First published as an Advance Article on the web 18th February 2003
A series of chromophores with high second-order nonlinearities has been synthesized; the chromphores consist
of triarylamine or dialkylarylamine donors linked by a conformationally locked polyene bridge to a
dicyanomethylidene acceptor. The use of bridges of this type, combined with the replacement of
dialkylarylamine with triarylamine donors, leads to high thermal stability without adverse affects on the
nonlinear optical properties of the chromophores.
ring systems (Fig. 1(b)), might be anticipated to increase
Introduction
stability by preventing any decomposition related to cis–trans
isomerization, and by steric protection of the polyene p-system.
This strategy was first applied to polymethine (cyanine) dyes;
several groups have incorporated polymethine chains into
ring systems (Figure 2 (a), (b)).12–20 In some cases enhanced
photostability has been observed; for example, the compound
in Fig. 2(a) was found to be some forty times more photo-
stable than the analogue in which the central ring is absent.18
More recently, several groups have applied the same strategy
to confomationally lock some or all of the double bonds
of donor–acceptor polyene NLO chromophores (Fig. 2 (c),
(d)).21–30 In several cases, comparisons of ring-locked and
non-ring-locked polyenes clearly demonstrate greater thermal
stability for the former class of compounds.21–24,27 It has also
been shown mb values attainable in ring-locked systems are
comparable to those in non-ring-locked polyenes.21,23,27,31
It has also been found that NLO chromophores based upon
triarylamine donors exhibit enhanced thermal stability rela-
tive to dialkylarylamines, presumably because of their lack of
a-hydrogens adjacent to the nitrogen.23,32,33 In this paper we
describe the synthesis of new chromophores in which triaryl-
amine donors (functionalized with solubilizing alkyl groups)
are combined with cyclohexene (m ~ 1) and tetrahydro-
naphthalene (m ~ 2) ring-locked bridges, and with the
dicyanomethylidene [LC(CN)2] acceptor. The optical proper-
ties of these species are compared with compounds with
dialkylarylamine ring-locked and non-ring-locked polyene
Electro-optic poled polymers are used in a variety of photonic
applications involving the switching or modulation of light.1–4
The poling process involves the use of electric fields to align
polar second-order nonlinear optical (NLO) guest chromo-
phores above the glass-transition temperature, Tg, of a polymer
host, in which they are dissolved, or to which they are
covalently tethered; the alignment is ‘‘frozen in’’ once the
polymer is cooled below Tg. A figure-of-merit for the second-
order nonlinear NLO activity of the poled polymer is mb, the
scalar product of the chromophore’s dipole moment, m, and the
vectorial part of its first hyperpolarizability tensor, b. An
additional factor affecting device efficiency is the homogeneity
of the refractive index within the material; chromophores
which are sparingly soluble in the polymer host may aggregate
with one other and cause scattering losses, or diminish poling
efficiency through unfavorable electrostatic interactions.5
Moreover, the long-term efficiency of a device depends upon
the stability both of the poling-induced chromophore align-
ment and of the guest–host mixture to phase separation. This
stability is increased if high-Tg (200–300 uC) host polymers are
used; however, the chromophore must then be thermally stable
at these temperatures in order to withstand the poling process.
In addition, device operation often involves exposure to high
intensity light, requiring the chromophores to be photostable.
Therefore, this paper describes work carried out to rationally
modify the structures of chromophores known to exhibit high
mb in order to increase their solubility, thermal stability, and
photostability without adversely affecting their second-order
nonlinear optical properties.
Compounds in which donors (D) and acceptors (A) are
linked by a polyene bridge (Fig. 1(a)) are well-known to exhibit
high mb;6–8 the nonlinearities exceed those of systems of
comparable conjugation length in which aromatic rings are
interposed between donor and acceptor.9 However, extended
polyenes are typically not sufficiently stable to withstand poling
at temperatures greater than 200 uC.10,11 Rigidly locking the
conformations of polyene chains, by their incorporation into
Fig. 1 General structure for (a) conventional and (b) ring-locked
polyene-based nonlinear optical chromophores. D and A are p-donor
and p-acceptor, respectively.
DOI: 10.1039/b208024a
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This journal is # The Royal Society of Chemistry 2003
825

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Chart 1 Building blocks for ring-locked NLO chromophores.
give the intermediate donor-substituted ketones 5a–d, 7b
and 9a–d (Scheme 1); the use of this method to introduce
4-(dialkylamino)aryl groups into ring-locked systems has
previously been described24,26 and was used, for example, in
the synthesis of the ketone precursor to the compounds shown
in Fig. 2(d).24 The 4-bromoanilines 4a–d were synthesized by
N-bromosuccinimide-bromination37 of the corresponding ani-
lines, which were either commercially available or which were
synthesized using palladium-catalyzed C–N bond-forming
reactions as described previously.38 Knoevenagel condensation
with malononitrile was used to convert the ketones (5a–d, 7b
and 9a–d) to the final products (6a–d, 8b and 10a–d), which
were readily purified by recrystallization (Scheme 1). The
tert-butyldimethylsilyl (TBDMS) protecting groups of 6d
and 10d were removed under acidic conditions39 to give the
corresponding hydroxy-functionalized chromophores 6e and
10e; hydroxy groups can be used for covalent attachment of
the NLO chromophore to a host polymer, which has been
shown to lead to improved alignment stability relative to
non-covalently-bound systems.40
Fig. 2 Previously reported examples of ring-locked systems: poly-
methines with (a) some12 and (b) all20 methine units incorporated into
rings; polyene NLO chromophores with polymethine with (c) some23
and (b) all24 methine units incorporated into rings.
Optical properties
analogues, and their redox, photochemical, and thermal
stabilities are investigated.
All of the chromophores in this study have an intense
solvatochromic absorption band in the visible region of the
spectrum; the molecular absorptivities lie between 3.1 6 104
and 5.2 6 104 M21 cm21 (Table 1). The absorption maxima of
the dialkylaminophenyl compounds 6a/6e and 10a/10e are
characterized by very similar energies and absorptivities to
those of the closely related non-ring-locked polyenes, 11 and 12
(Chart 2) respectively. The data for 10a, 10e and 12 also closely
parallel that reported for the similar compound shown in
Results and discussion
Synthesis
The molecules were assembled using the conformationally
locked polyene-derivatives 3-ethoxy-2-cyclohexen-1-one, 1,
3-(dimethylamino)-5,5-dimethyl-2-cyclohexen-1-one, 2, and
7-methoxy-4,4a,5,6-tetrahydro-2(3H)-naphthalenone,34–36
3
(Chart 1). The donors were introduced by reaction of the
ketones 1–3 with lithiated 4-bromoaniline derivatives (4a–d) to
{Reagents: (i) nBuLi, Et2O; (ii) 1; (iii) 2; (iv) 3; (v) CH2(CN)2, EtOH,
piperidine, D; (vi) AcOH, THF, H2O.
Scheme 1 Synthesis of conformationally locked chromophores.{
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Table 1 Linear and nonlinear optical properties of ring-locked and non-ring-locked polyene chromophores
max/M21cm21
lmax/nm
(pentane)
lmax/nm
(CHCl3)
lmax/nm
(DMF)
lmax/nm
(CH2Cl2)
e
(CH2Cl2)
mb/10248 esua
(CHCl3)
11
6a
6b
6c
6e
8b
12
10a
10b
10c
10f
–
486
490
490
482
474
490
520
522
512
504
502
–
490
485
481
474
471
482
522
519
503
497
502
4.6 6 104
4.7 6 104
3.8 6 104
3.1 6 104
4.2 6 104
3.1 6 104
4.7 6 104
5.2 6 104
4.1 6 104
3.8 6 104
4.6 6 104
6896
450
464
452
440
460
–
484
486
468
460
492
474
474
486
478
–
522
498
494
522
700
14706
1800
1580
aDetermined by EFISH using 1.9 mm fundamental radiation.
Chart 2 Model non-ring-locked NLO chromophores.
Fig. 2(d) (n ~ 1).24 Moreover, little difference is seen between
the two species in which the donor is the same, but in which the
one-ring bridging group differs (6b and 8b). Values of mb were
determined for some of the compounds, using electric-field-
induced second-harmonic generation (EFISH) measurements
in chloroform.41–43 Table 1 shows that dialkylaminophenyl-
substituted conformationally locked chromophores 6e and 10e
show similar nonlinearities to the unbridged model compounds
11 and 12.6 The linear and nonlinear optical data clearly
confirm that incorporation of a polyene bridge into a con-
formationally locked ring system does not significantly affect
the electronic structure of the chromophore, consistent with the
findings of several previous studies.22,24,27
Fig. 3 Cyclic voltammograms (dichloromethane, 0.1 M [nBu4N]1[PF6]2,
potential vs. ferrocene/ferrocenium) of ring-locked polyene 10a and its
non-ring-locked analogue 12.
Table 2 Electrochemical half-wave potentials vs. ferrocenium/ferro-
cene for ring-locked and non-ring-locked-polyene chromophores,
2
measured using cyclic voltammetry in 0.1
dichloromethane solution at 50 mVs21
M
[nBu4N1][PF6
]
Electrochemistry
Compound, m
E1/2 (m1/m)/mV
E1/2 (m/m2)/mV
The electrochemistry of some of the conformationally locked
polyenes, m, were studied by cyclic voltammetry in dichloro-
methane; all the voltammograms displayed two quasi-rever-
sible processes which we assign to m1/m and m/m2 couples.
For most of these couples, oxidation and reduction currents
were equal. For two of the cyclohexene-bridged species (6a, 6b)
the oxidation currents for the m/m2 couple were somewhat
smaller than those for reduction (Iox/Ired ~ ca. 0.5–0.7), and
additional oxidation features were observed at more positive
potential; this indicates that, although the electron-transfer
kinetics are reversible, some the radical anions undergo
chemical reaction before reoxidation, i.e. the reduction is a
so-called EC process.44 However, the radical anions of the
polyene reference compounds are clearly much less stable than
those of 6a and 6b; 11 and 12 (Fig. 3) showed reductions with
almost no observable reoxidation current (Iox ~ ca. 0), i.e. the
chemical reaction undergone by the radical anions is much
more rapid than for those of the ring-locked species).
11
6a
6b
6c
12
10a
10b
1550
1470
1460
1460
1380
1330
1410
21600a
21830b
21740b
21800
21450a
21690
21630
aEstimated E1/2, apparent EC process in which oxidation peak barely
observed. bNot fully reversible, Iox/Ired ~ 0.5–0.7, with additional
oxidation features seen at higher potential.
potentials. It is possible that some type of structural relaxation,
not possible in the ring-locked polyenes, takes place in the
radical anion of the free polyene on the timescale of the elec-
tron transfer, stabilizing the anion with respect to reoxidation
and shifting the couple to less negative potential (the relaxed
species then undergoes a chemical reaction, resulting in the
observed EC behavior).
The half-wave potentials (E1/2
) for the processes are
summarized in Table 2. Interestingly, the EC m/m2 couples
of the parent compounds 11 and 12 occur at considerably less
negative potentials than those of their closest conformationally
locked analogues (shown for 12 vs. 10a in Fig. 3), whilst the
m1/m processes occur at more comparable potentials. The
similarity of the visible spectra of ring-locked and parent
polyenes suggest that there is little difference in the orbital
energies of the neutral poyenes, so the electron-donating effect
of the aliphatic rings upon the polyene chains in the ring-locked
species is probably not responsible for the difference in
While simple dialkylarylamines are typically ca. 400 mV
more readily oxidized then their triarylamine analogues,45 the
triarylamine–cyclohexene derivative, 6b, undergoes oxidation
at similar potential to its dialkylarylamino analogue, 6a.
However, 6a is less readily reduced to its anion than 6b.
Evidently, stronger p-donation to the acceptor in the
dialkylarylamino species effectively cancels the differences in
m1/m potential expected by analogy with the simple amines.
The additional methoxy functionality of 6c also has a larger
effect upon m/m2 than on m1/m. In the tetrahydronaphthalene
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derivatives the dialkylarylamine compound, 10a, is now
slightly more readily oxidized than its triarylamine analogue,
10b, indicating reduced coupling of the donor and the acceptor
through the longer polyene bridge.
The enhanced stability, with respect to decomposition, of the
radical anions of the ring-locked polyenes, as revealed by much
larger values of Iox/Ired for the m/m2 couples, may be important
in device applications. In electrooptic-device fabrication,
poling requires application of large electric fields to the
material, which could result in some temporary molecular
oxidation or reduction. In addition, chromophores that can be
converted to stable radical cations or anions can potentially
serve as charge-transport components in photorefractive
composites.1
Fig. 5 Thermogravimetric analysis results for the ring-locked chromo-
phores 10a and 10b, and for their non-ring-locked analogue 12.
Photochemical stability
When polymethylmethacrylate (PMMA) films of 6a, 6b, 10a
and 10c were irradiated at 632 nm (0.4 mW) for 24 h, their
refractive indices all changed by less than ¡0.05%, within the
error of the measurement. Disperse Red 1, an azo-based
chromophore known to undergo a photoinduced trans–cis
isomerization,46 was used as a reference substance and showed
severe changes in refractive index during these measurements.
The conformationally locked chromophores (6a, 6b, 10a
and 10c) are, therefore, considerably more photostable than
Disperse Red 1 under irradiation at 632 nm.47 Photostability
was also investigated exposing the polymer films to constant
intensity broadband UV-light from a high-pressure mercury
lamp. Changes in the absorbance at lmax were monitored both
in nitrogen-purged conditions and under air. All chromophores
remain photostable under nitrogen atmosphere (Fig. 4(a)). In
the presence of oxygen, all four compounds studied undergo
considerable decomposition (Fig. 4(b)). However, the two spe-
cies with triarylamine donor groups (6b, 10b) are significantly
more photostable under these conditions than their respective
dialkylarylamine analogues (6a, 10a).
Thermal stability
The relative thermal stabilities of the chromophores were
invesitgated using thermogravimetric analysis (TGA) and
differential scanning calorimetry (DSC). The TGA results
obtained for selected chromophores are shown in Fig. 5; the
decomposition onset temperatures, Td(onset, TGA) (Table 3),
were estimated as the temperature at which weight loss was
first detectable. It should be noted that weight loss in these
experiments may be due to sublimation and/or decomposition
of the substance.
DSC measurements reveal more-or-less similar trends; the
onset decomposition temperatures estimated from the DSC
are, in general, higher than the temperatures at which the
compounds start loosing mass in the TGA. The DSC data also
show endothermic melting processes that provide evidence of
reduced intermolecular interactions in the conformationally
locked systems; for example, the parent polyene 12 melts at
a significantly higher temperature than the conformationally
locked 10a and 10b (Fig. 6).
Comparison of Td obtained from TGA and DSC shows that
the former technique affords a more conservative estimate
of the thermal stability in these compounds (although the
opposite was recently found for another NLO chromophore30).
Clearly, comparison of thermal stabilities estimated using
different techniques must be made with great care. Indeed Jen
and co-workers have previously found that monitoring the
absorption of polyquinoline films of chromophores also gave
lower estimates of the decomposition temperature than use
of DSC. The data are clearly consistent with previous findings
in other donor–acceptor polyene systems22,24,27 in showing that
conformational locking of the polyene chain substantially
raises the thermal stability of the chromophores. Both DSC
Table 3 Temperatures of decomposition onset determined by TGA
and DSC
Compound
Td(onset, TGA)/uC
Td(onset, DSC)/uC
11
6a
6b
6c
6e
8
12
10a
10b
10c
10e
204
227
263
286
282
246
209
280
336
330
279
199
320
350
370
280
390
210
350
380
380
290
Fig. 4 UV-degradation of PMMA films of ring-locked chromophores:
(a) under nitrogen, and (b) in air.
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Experimental section
Ultraviolet-visible electronic absorption (UV-vis) spectra were
recorded on Hewlett-Packard 8452A or Perkin-Elmer Lambda
9 spectrophotometers. 1H and 13C NMR spectra were recorded
using a General Electric QE-300 spectrometer. Elemental
analyses were performed by Atlantic Microlabs, Norcross,
GA. Cyclic voltammetry was performed under argon on dry
dichloromethane solutions ca. 1024 M in sample and 0.1 M in
[nBu4N]1[PF6]2 using a glassy carbon working electrode, a
platinum auxiliary electrode, a AgCl/Ag pseudo-reference
electrode, and a BAS 100B potentiostat. Potentials were
referenced by the addition of ferrocene to the cell, and are
quoted to the nearest 10 mV relative to the ferrocenium–
ferrocene couple. mb values were determined by EFISH (electric
field induced second harmonic generation) using 1.9 mm
fundamental radiation in chloroform, using a set-up similar
to that previously described.48 Films were prepared by spin-
coating solutions of chromophore and polymethylmethacrylate
(PMMA) (5% by weight chromophore in PMMA) onto ITO-
coated glass. The photostabilities were investigated in a
Metricon prism coupler; PMMA-films (1.5–2.5 mm thick) of
the compounds were exposed to 0.4 mW of 632 nm light for
24 h while monitoring the refractive index as a function of
irradiation. As a reference, we used Disperse Red 1 (Aldrich), a
compound which is known to undergo trans–cis photoisomer-
ization.46 Thermogravimetric analysis (TGA) and differential
scanning calorimetry (DSC) were performed under a nitrogen
atmosphere, on a Shimadzu TGA-50 or a Shimadzu DSC-50,
respectively, at a heating rate of 10 uC min21. DSC measure-
ments were performed on sealed samples. Diethyl ether was
distilled from sodium benzophenone-ketyl under nitrogen.
N,N-Bis(4-n-butylphenyl)aniline and 4-bromo-N,N-bis(4-n-
butylphenyl)-3-methoxyaniline were prepared using a literature
method.38 N,N-Di-n-butylaniline, tert-butyldimethylsilyl chlor-
ide, imidazole, 2.5 M n-butyllithium in hexanes, malononitrile,
N-bromosuccinimide and piperidine were purchased from
Aldrich and used as received. Ethylphenylethanolamine was
purchased from Henkel Cie. and distilled under vacuum.
Fig. 6 Differential scanning calorimetry results for the ring-locked
chromophores 10a and 10b, and for their non-ring-locked analogue 12.
and TGA indicate that the compounds with triarylamine
donors (6b, 6c, 6e, 10b and 10e) are more stable than their
dialkylaryl analogues (6a, 6f, 10a, and 10f) as observed in other
donor–acceptor NLO chromophores;23,32,33 it is interesting
that the effects of these two stabilising features on Td appear to
be additive. Some of our conformationally locked species have
some of the highest thermal stabilities reported for polyene
chromophores, although, direct comparison with other work-
ers’ data is hampered by the variety of methods that have been
used to estimate decomposition points from TGA and DSC
data, and by variations in scan rates used by different workers.
Despite the problems in comparing data from different
sources mentioned above, some useful comparisons can be
made. The DSC value found for 12 is lower than that seen for
its N,N-diethyl analogue (252 uC),24 whilst 10a shows similar
stability to that reported by Jen and co-workers for the closely
related compound shown in Fig. 2(c) (n ~ 1; DSC Td
w
350 uC),24 and somewhat higher stability than that for a closely
related compound in which only one of the double bonds is
incorporated into a ring (the molecule represented by Fig. 2(c);
R ~ Me, TGA 220 uC;23 R ~ Et, DSC 336 uC22,24). On the
other hand, 10b and 10c exhibit slightly lower decomposition
points according to TGA relative to an analogue in which
only one of the double bonds is ring-locked (the molecule
represented by Fig. 2(c) with R ~ p-tolyl; 344 uC),23 although it
is possible that the long solubilising alkyl chains of 10b and 10c
react here first, rather than the bridge itself, or that the different
scan rates involved in the measurement play a role. It should
also be noted that other features of the molecule, besides those
investigated here, can play a role in imparting high thermal
stability; for example, a recent chromophore with a vinylene–
dialkylthiophenylene–vinylene bridge and a complex cyanide-
functionalised heterocyclic acceptor, decomposes at very high
temperature (DSC 312 uC; TGA 315 uC) for a species with a
(dialkylamino)phenyl donor.30
General method for the bromination of aniline derivatives
A solution of 0.05 mol N-bromosuccinimide in 25 mL N,N-
dimethylformamide was added to a stirred solution of 0.05 mol
(1 eqiv.) of the aniline derivative in 25 mL N,N-dimethylfor-
mamide at 0 uC. The resulting green solution was stirred for
12 h at ambient temperature and then poured into 1 L of water.
The mixture was extracted three times with dichloromethane.
The combined organic layers were washed subsequently with
water and 200 mL of saturated sodium thiosulfate solution,
dried over sodium sulfate, filtered and evaporated to yield the
bromides 4a–d as oils. The reactions were carried out on scales
varying from 0.01 to 0.44 mol of aniline derivative.
4-Bromo-N,N-di-n-butylaniline (4a). The general method for
the bromination was used with N,N-di-n-butylaniline (11.0 g,
0.054 mol). Yellowish oil, yield 14.2 g (0.050 mol, 93%). 1H
NMR (300 MHz, CDCl3) d 7.23 (d, J ~ 9.1 Hz, 2H, CH); 6.48
(d, J ~ 9.0 Hz, 2H, CH); 3.21 (t, J ~ 8.5 Hz, 4H, CH2N); 1.52
(q, J ~ 7.6 Hz, 4H, CH2); 1.34 (q, J ~ 7.3 Hz, 4H, CH2); 0.93
(t, J ~ 7.3 Hz, 6H, CH3). 13C NMR (75 MHz, CDCl3) d 147.0,
131.8, 113.3, 106.6, 50.9, 29.2, 20.3, 14.0. HRMS calculated m/z
283.0936; found m/z 283.0924.
Conclusions
A series of ring-locked polyene NLO chromophores has been
synthesized. The incorporation of the polyene bridge into rings
has little effect on the molecules’ linear and nonlinear optical
properties. Electrochemical data show that the radical anions
of the ring-locked species are considerably more stable
with respect to decomposition than those of their non-ring-
locked analogues. Combining conformationally locked polyene
bridges with triarylamine donors leads to chromophores
which have both high mb values and high thermal stability,
with decomposition temperatures around 300 uC. The triaryl-
amine species also show higher photostability in the presence
of oxygen than their dialkylarylamine analogues.
4-Bromo-N,N-bis(4-n-butylphenyl)aniline (4b). The general
method for the bromination was used with N,N-bis(4-n-
butylphenyl)aniline (18.0 g, 0.050 mol). Yellowish oil, yield
1
19.7 g (0.045 mol, 89%). H NMR (300 MHz, CDCl3) d 7.33
(d, J ~ 8.9 Hz, 2H, CH); 7.13 (d, J ~ 8.3 Hz, 4H, CH); 6.96 (d,
J ~ 8.5 Hz, 4H, CH); 6.85 (d, J ~ 8.8 Hz, 2H, CH); 2.57 (t, J ~
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7.7 Hz, 4H, CH2); 1.58 (quint., J ~ 7.7 Hz, 4H, CH2); 1.35
(sext, J ~ 7.4 Hz, 4H, CH2); 0.91 (t, J ~ 7.3 Hz, 6H, CH3). 13
NMR (75 MHz, CDCl3) d 168.9, 145.5, 138.7, 132.4, 129.9,
125.3, 124.1, 121.1, 35.3, 34.2, 22.7, 13.5. HRMS calculated m/z
435.1562; found m/z 435.1545.
(5.25 g, 12.6 mmol) and 1. Yellow solid, yield 4.62 g (10.2 mmol,
85%). 1H NMR (300 MHz, CD2Cl2) d 7.44 (d, J ~ 8.8 Hz, 2H,
CH); 7.14 (d, J ~ 8.3 Hz, 4H, CH); 7.04 (d,m J ~ 8.3 Hz, 4H,
CH); 6.92 (d, J ~ 8.8 Hz, 2H, CH); 6.32 (s, 1H, CH); 2.74
(t, J ~ 5.8 Hz, 2H, CH2); 2.58 (t, J ~ 7.5 Hz, 4H, CH2 ); 2.40
(t, J ~ 6.5 Hz, 2H, CH2); 2.10 (t, J ~ 6.5 Hz, 2H CH2 ); 1.62–
1.54 (m, 4H, CH2); 1.43 (sext, J ~ 7.4 Hz, 4H, CH2); 0.94 (t,
J ~ 7.3 Hz, 6H, CH3). 13C NMR (75 MHz, CDCl3) d 199.8,
158.9, 150.0, 144.3, 138.8, 129.3, 126.6, 129.9, 125.4, 122.7,
120.3, 37.2, 35.0, 33.6, 27.5, 22.7, 22.6, 13.9. HRMS calculated
m/z 451.2875; found m/z 451.2877. Anal. calcd C 85.09, H 8.25,
N 3.10; found C 85.09, H 8.29, N 3.13.
C
4-Bromo-N,N-bis(4-n-butylphenyl)-3-methoxyaniline (4c). The
general method for the bromination was used with N,N-bis(4-n-
butylphenyl)-3-methoxyaniline (4.0 g, 0.010 mol). Yellowish oil,
yield 4.8 g (0.009 mol)90%. Used without further characterization.
2-[N-Ethyl-N-4-bromophenylamino]-1-tert-butyldimethylsilyl-
oxyethane (4d). The general method for the bromination was
used with ethylphenylethanolamine (72.5 g, 0.44 mol). Yellow-
ish oil, yield 102 g (0.42 mol, 95%). 1H NMR (300 MHz,
CDCl3) d 7.26 (d, J ~ 8.9 Hz, 2H, CH); 6.61 (d, J ~ 8.9 Hz,
2H, CH); 3.74 (m, 2H, OCH2); 3.33–3.44 (m, 4H, NCH2);
2.36 (br, 1H, OH); 1.12 (t, J ~ 7.1 Hz, 3H, CH3). 13C NMR
(75 MHz, CDCl3) d 147.0, 131.9, 114.1, 108.1, 59.8, 52.4, 45.5,
11.6. 4.8 g (0.02 mol) of the obtained bromide was stirred with
40 mL anhydrous N,N-dimethylformamide, 3.2 g (0.02 mol,
1.1 equiv.) tert-butyldimethylsilyl chloride and 2.9 g (0.04 mol,
2.2 equiv.) imidazole for 2 h. After adding 200 mL of water,
the mixture was extracted with dichloromethane. The organic
layer was washed subsequently with 1% hydrochloric acid
and saturated sodium thiosulfate solution, dried over sodium
sulfate, filtered and evaporated. The residue was filtered
through silica gel, eluent cyclohexane : ethyl acetate 10 : 1,
yielding 7.4 g (0.02 mol, 95%) 4d as a yellow oil. 1H NMR
(300 MHz, CDCl3) d 7.25 (s, J ~ 9.1 Hz, 2H, CH); 6.55 (d, J ~
9.1 Hz, 2H, CH); 3.73 (t, J ~ 6.3 Hz, 2H, OCH2); 3.33–3.41 (m,
4H, NCH2); 1.14 (t, J ~ 7.0 Hz, 3H, CH3); 0.89 (s, 9H, CH3);
0.04 (s, 6H, CH3). 13C NMR (75 MHz, CDCl3) d 146.8, 135.9,
131.8, 113.2, 60.5, 52.5, 45.5, 25.9, 18.2, 11.9, 25.4. HRMS
calculated m/z 357.1124; found m/z 357.1109.
3-[N,N-Bis(4-n-butylphenyl)-3-methoxyaniline-4-yl]-cyclohex-
2-enone (5c). The general method for ketone synthesis was
used with 4c (4.2 g, 9.0 mmol) and 1. Yellow solid, yield 3.8 g
(7.8 mmol, 87%). 1H NMR (300 MHz, CD2Cl2) d 7.12 (d, J ~
8.3 Hz, 4H, CH); 7.07 (d, J ~ 9.0 Hz, 1H); 7.04 (d, J ~ 8.3 Hz,
4H, CH); 6.55 (d, J ~ 1.8, 1H CH); 6.50 (dd, J1 ~ 2.1 Hz, J2 ~
8.7 Hz, 1H, CH); 6.21 (s, 1H, CH); 3.62 (s, 3H, OCH3); 2.72 (t,
J ~ 6.5 Hz, 2H, CH2); 2.58 (t, J ~ 7.5 Hz, 4H, CH2); 2.37 (t,
J ~ 6.5 Hz, 2H, CH2); 2.07 (t, J ~ 6.5 Hz, 2H CH2); 1.62–1.54
(m, 4H, CH2); 1.40 (sext, J ~ 7.4 Hz, 4H, CH2); 0.94 (t, J ~
7.3 Hz, 6H, CH3). 13C NMR (75 MHz, CDCl3) d 200.1, 160.7,
157.9, 150.7, 144.6, 138.6, 129.4, 129.2, 126.9, 125.3, 121.4,
113.2, 104.2, 55.3, 37.5, 35.1, 33.6, 30.0, 23.4, 22.4, 14.0. HRMS
calculated m/z 481.2981; found m/z 481.2974.
3-[N-Ethyl-N-2-(tert-butyldimethylsiloxy)ethyl]aniline-4-yl-2-
cyclohex-2-enone (5d). The general method for ketone-synth-
esis was used with 4d (16.5 g, 0.046 mol) and 1. Yellow oil, yield
1
13.5 g (0.036 mol, 78%). H NMR (300 MHz, CDCl3) d 7.45
(d, J ~ 9.2 Hz, 2H, CH); 6.64 (d, J ~ 9.2 Hz, 2H, CH); 6.38 (s,
1H, CH); 3.74 (t, J ~ 6.3 Hz, 2H, OCH2); 3.45 (t, J ~ 6.3 Hz,
2H, NCH2); 3.43 (q, J ~ 7.1 Hz, 2H, NCH2); 2.71 (t, J ~
6.0 Hz, 2H, CH2); 2.42 (t, J ~ 6.5 Hz, 2H, CH2); 2.08 (quint,
J ~ 6.3 Hz, 2H, CH2); 1.15 (t, J ~ 7.1 Hz, CH3); 0.86 (s, 9H,
CH3); 0.00 (s, 6H, CH3). 13C NMR (75 MHz, CDCl3) d 200.0,
159.5, 149.5, 127.7, 124.3, 120.8, 111.1, 60.5, 52.3, 45.5, 37.2,
General procedure for ketone synthesis
1.1 equiv. n-butyllithium (2.5 M solution in hexanes) were
added to a solution of 0.1 mol of the desired 4-bromoaniline
derivative (4a–d) in dry diethyl ether at 210 uC. After stirring
for 2 h at 210 uC, the reaction mixture was allowed to warm up
to 0 uC. A solution of 1 eqiv. of the desired ketone (1–3) in
diethyl ether was added. The reaction mixture was warmed to
ambient temperature and stirred for 2.5 h. After addition of
a saturated aqueous solution of sodium chloride, the organic
layer was separated. The aqueous layer was extracted with two
portions of diethyl ether. The combined organic layers were
dried over sodium sulfate, filtered and evaporated to give
a residue, which was purified by column chromatography on
silica gel with a mixture of hexanes and ethyl acetate as eluent.
The reactions were carried out on scales of 0.001–0.046 mmol
of 4-bromoaniline.
27.3, 25.8, 22.8, 18.3, 12.1, 25.4. UV-vis (CH2Cl2) lmax
~
375 nm, e (375) ~ 2.9 6 104 M21cm21. HRMS: calculated m/z
379.2437; found m/z 373.2428. Anal. calcd C 70.73, H 9.44, N
3.75; found C 70.58, H 9.45, N 3.79.
5,5-Dimethyl-3-[N,N-bis(4-n-butylphenyl)aniline-4-yl]-cyclohex-
2-enone (7b). The general method for ketone synthesis was
used with 4b (5.07 g, 11.6 mmol) and 2. Yellow oil, yield 816 mg
(1.70 mmol, 16%). 1H NMR (300 MHz, CD2Cl2) d 7.44 (d, J ~
8.8Hz, 2H, CH); 7.15 (d, J~8.3Hz, 4H, CH); 7.05 (d, J~8.3 Hz,
4H, CH); 6.98 (d, J ~ 8.8 Hz, 2H, CH); 6.36 (s, 1H, CH); 2.62
(s, 2H, CH2); 2.60 (t, J ~ 6.5, 4H, CH2); 2.29 (s, 2H, CH2);
1.63–1.56 (m, 4H, CH2); 1.43 (sext, J ~ 7.4 Hz, 4H, CH2); 1.12
(s, 6H, CH3); 0.96 (t, J ~ 7.3 Hz, 6H, CH3). 13C NMR (75 MHz,
CDCl3) d 200.0, 156.8, 150.3, 144.6, 138.9, 130.2, 129.5, 127.2,
125.6, 121.9, 120.6, 51.1, 42.0, 35.2, 33.8, 33.7, 28.7, 22.6, 14.1;
HRMS calculated m/z 479.3188; found m/z 479.3189.
3-(N,N-Di-n-butylaniline-4-yl)-cyclohex-2-enone (5a). The
general method for ketone synthesis was used with 4a (12.3 g,
0.043 mol) and 1. Yellow solid, yield 10.2 g (0.034 mol, 79%).
1H NMR (300 MHz, CDCl3) d 7.46 (d, J ~ 9.0 Hz, 2H, CH);
6.60 (d, J ~ 8.9 Hz, 2H, CH); 6.38 (s, 1H, CH); 3.29 (t, J ~
7.6 Hz, 4H, CH2N); 2.72 (t, J ~ 6.0 Hz, 2H, CH2); 2.42 (t, J ~
6.6 Hz, 2H, CH2); 2.08 (q, J ~ 6.3 Hz, 2H, CH2); 1.56 (q,
J ~ 7.5 Hz, 4H, CH2); 1.34 (sext, J ~ 7.4 Hz, 4H, CH2); 0.94
(t, J ~ 7.3 Hz, 6H, CH3). 13C NMR (75 MHz, CDCl3) d 200.0,
159.5, 149.6, 127.7, 123.8, 120.7, 111.1, 50.7, 37.2, 29.4, 27.3,
22.8, 20.3, 14.0. UV-vis (CH2Cl2) lmax ~ 380 nm; e (380) ~
3.2 6 1024 M21 cm21. HRMS calculated m/z 299.2249; found
m/z 299.2247.
7-[N,N-Dibutylaniline-4-yl]-4,4a,5,6-tetrahydro-2(3H)-naphtha-
lenone (9a). The general method for ketone synthesis was used
with 4a (0.50 g, 1.76 mmol) and 3. Yellow oil, yield (337 mg,
0.96 mmol, 55%). 1H NMR (300 MHz, CDCl3) d 7.42 (d, J ~
9.0 Hz, 2H, CH); 6.59 (d, J ~ 9.0 Hz, 2H, CH); 6.56 (s, 1H,
CH); 5.83 (s, 1H, CH); 3.28 (t, J ~ 7.4 Hz, 4H, CH2); 2.76–2.84
(m, 1H, CH2); 2.35–2.64 (m, 4H, CH2 & CH); 2.02–2.13 (m,
2H, CH2); 1.65–1.80 (m, 1H, CH2); 1.44–1.60 (m, 5H, CH2);
1.33 (sext, J ~ 7.4 Hz, 4H, CH2); 0.93 (t, J ~ 7.3 Hz, 6H,
CH3). 13C NMR (75 MHz, CDCl3) d 200.0, 160.4, 148.7, 148.3,
126.9, 125.5, 122.4, 120.4, 111.2, 50.7, 37.9, 35.6, 30.2, 29.8,
29.4, 27.8, 20.3, 14.0. HRMS calculated m/z 351.2562; found
m/z 351.2556.
3-[N,N-Bis(4-n-butylphenyl)aniline-4-yl]-cyclohex-2-enone (5b).
The general method for ketone synthesis was used with 4b
830
J. Mater. Chem., 2003, 13, 825–833

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7-[N,N-Bis(4-n-butylphenyl)aniline-4-yl]-4,4a,5,6-tetrahydro-
2(3H)-naphthalenone (9b). The general method for ketone-
synthesis was used with 4b (5.00 g, 11.4 mmol) and 3. Yellow
oil, yield 4.13 g (8.2 mmol, 72%). 1H NMR (300 MHz, d6-
acetone) d 7.49 (d, J ~ 8.8 Hz, 2H, CH); 7.15 (d, J ~ 8.3 Hz,
4H, CH); 6.99 (d, J ~ 8.5 Hz, 4H, CH); 6.91 (d, J ~ 8.8 Hz,
2H, CH); 6.72 (s, 1H, CH); 5.78 (s, 1H, CH); 2.62–2.83 (m, 2H,
CH2); 2.58 (t, J ~ 7.7 Hz, 4H, CH2); 2.35–2.38 (m, 2H, CH2);
2.07–2.12 (m, 2H, CH2); 1.53–1.64 (m, 7H, CH2, CH); 1.38
2H, CH2); 1.52–1.63 (m, 4H, CH2); 1.29–1.41 (t 6 d, Jd ~ Jt ~
7.5 Hz, 4H, CH2); 0.95 (t, J ~ 7.3 Hz, 6H, CH3). 13C NMR
(75 MHz, CDCl3) d 170.1, 157.8, 150.5, 128.5, 123.4, 115.9,
114.5, 113.8, 111.4, 73.8, 50.8, 29.4, 29.2, 27.4, 21.7, 20.3, 13.9.
Anal. calcd C 79.50, H 8.41, N 12.09; found C 79.45, H 8.41,
N 12.09.
3-[N,N-Bis(4-n-butylphenyl)aniline-4-yl]-1-dicyanomethylidene-
2-cyclohexene (6b). Thegeneralmethod for the Knoevenagel-type
condensation was used with 5b (4.00 g, 8.85 mmol). Red crystals,
yield 3.63 g (7.26 mmol, 82%), mp. 120–122 uC. 1H NMR
(300 MHz, CD2Cl2) d 7.51 (d, J ~ 8.9 Hz, 2H, CH); 7.16 (d, J ~
8.3 Hz, 4H, CH); 7.12 (s, 1H,CH); 7.06 (d, J ~ 8.3 Hz, 4H, CH),
6.94 (d, J ~ 8.9 Hz, 2H, CH); 2.79–2.74 (m, 4H, CH2); 2.58 (t, J ~
7.5 Hz, 4H, CH2); 1.97 (t, J ~ 6.3, 2H, CH2); 1.62 (m, 4H, CH2);
(sext. J ~ 7.4 Hz, 4H, CH2); 0.93 (t, J ~ 7.3 Hz, 6H, CH3). 13
C
NMR (75 MHz, d6-acetone) d 198.6, 159.5, 149.7, 147.8, 145.8,
139.2, 132.8, 130.2, 127.3, 125.9, 124.1, 123.4, 121.8, 38.4, 36.0,
35.6, 34.5, 31.0, 30.6, 28.5, 23.0, 14.2. HRMS calculated m/z
503.3188; found m/z 503.3168.
1.33 (sext, J~7.4Hz, 4H, CH2);0.94 (t, J~7.3 Hz, 6H, CH3). 13
C
7-[N,N-Bis(4-n-butylphenyl)-3-methoxyaniline-4-yl]-4,4a,5,6-
tetrahydro-2(3H)-naphthalenone (9c). The general method for
ketone synthesis was used with 4c (2.9 g, 6.2 mmol) and 3.
NMR (75 MHz, CDCl3) d 169.6, 157.4, 151.1, 143.8, 139.5, 129.5,
128.6, 127.5, 125.8, 119.6, 117.9, 114.0, 113.2, 75.9, 35.1, 33.6, 29.2,
27.6, 22.4, 21.6, 14.0. UV-vis (CH2Cl2): lmax ~ 481 nm; e (481) ~
3.8 6 104 M21cm21. Anal. calcd C 84.12, H 7.47, N 8.40; found
C 84.05, H 7.46, N 8.42.
1
Yellow oil, yield 1.9 g, (3.5 mmol, 56%). H NMR (300 MHz,
CD2Cl2) d 7.12 (d, J ~ 8.8 Hz, 4H, CH); 7.06 (d, J ~ 7.5 Hz,
1H, CH); 7.03 (d, J ~ 8.3 Hz, 4H, CH); 6.56 (d, J ~ 1.8, 1H,
CH); 6.51 (dd, J1 ~ 2.1 Hz, J2 ~ 6.7 Hz, 1H, CH); 6.49 (s,1H,
CH); 5.74 (s, 1H, CH); 3.62 (s, 3H, OCH3); 2.74–2.62 (m, 2H,
CH2); 2.58 (t, J ~ 7.5 Hz, 4H, CH2); 2.35–2.38 (m, 2H, CH2);
2.07–2.12 (m, 2H, CH2); 1.53–1.64 (m, 7H, CH2, CH); 1,39
3-[N,N-Bis(4-n-butylphenyl)-3-methoxyaniline-4-yl]-1-dicyano-
methylidene-2-cyclohexene (6c). The general method for the
Knoevenagel-type condensation was used with 5c (1.8 g,
3.8 mmol). Orange crystals, yield 1.73 g (3.3 mmol, 86%), mp.
151–154 uC. 1H NMR (300 MHz, CD2Cl2) d 7.32 (d, J ~
1.8 Hz, 1H, CH); 7.21 (d, J ~ 8.7 Hz, 1H, CH); 7.15 (d, J ~
8.3 Hz, 4H, CH); 7.05 (d, J ~ 8.3 Hz, 4H, CH); 6.50 (s, 1H,
CH); 6.49 (dd, J1 ~ 1.8 Hz, J2 ~ y9 Hz, 1H, CH); 3.64 (s, 3H,
OCH3); 2.77–2.74 (m, 4H, CH2); 2.61 (t, J ~ 7.5 Hz, 4H, CH2);
1.93 (m, 2H, CH2); 1.58 (m, 4H, CH2); 1.38 (sext, J ~ 7.4 Hz,
4H, CH2); 0.94 (t, J ~ 7.3 Hz, 6H, CH3). 13C NMR (75 MHz,
CDCl3) d 170.7, 159.1, 157.9, 151.6, 144.0, 139.2, 129.9, 129.4,
125.7, 122.0, 119.8, 115.5, 113.7, 112.5, 103.2, 75.8, 55.3, 37.1,
29.8, 29.2, 22.4, 22.1, 14.0. UV-vis (CH2Cl2): lmax ~ 474 nm; e
(474) ~ 3.1 6 104 M21 cm21. Anal. calcd C 81.62, H 7.42, N
7.93; found C 81.57, H 7.44, N 7.88.
(sext, J ~ 7.4 Hz, 4H, CH2); 0.93 (t, J ~ 7.3 Hz, 6H, CH3). 13
C
NMR (75 MHz, CDCl3) d 200.0, 159.8, 157.7, 147.7, 149.2,
144.8, 138 2, 129.2, 126.4, 125.0, 123.4, 123.3, 123.3, 113.9,
105.1, 55.4, 38.1, 35.7, 35.0, 33.6, 30.3, 30.3, 30.2, 22.4, 13.9 (2C
overlapping in aromatic region). Anal. calcd C 83.26, H 8.12 N
2.62; found C 82.93, H 8.16, N 2.61.
7-[N-Ethyl-N-2(tert-butyldimethylsiloxyethyl)aniline-4-yl]-4,4a,5,6-
tetrahydro-2(3H)-naphthalenone (9d). The general method for
ketone synthesis with 4d (15.74 g, 0.044 mol) and 3 was used.
Yellow solid after sublimation at 10 mTorr, 210 uC, 58% yield
(10.22 g, 0.024 mol, 58%). 1H NMR (300 MHz, CDCl3) d 7.42
(d, J ~ 8.9 Hz, 2H, CH); 6.64 (d, J ~ 9.0 Hz, 2H, CH); 6.56
(s, 1H, CH); 5.83 (s, 1H, CH); 3.74 (t, J ~ 6.4 Hz, 2H, OCH2);
3.39–3.46 (m, 4H, NCH2); 2.75–2.78 (m, 1H, CH); 2.39–2.61
(m, 4H, CH2); 2.00–2.15 (m, 2H, CH2); 1.68–1.81 (m, 1H,
CH2); 1.41–1.60 (m, 1H, CH2); 1.15 (t, J ~ 7.0 Hz, 3H, CH3);
0.87 (s, 9H, CH3); 0.02 (s, 6H, CH3). 13C NMR (75 MHz,
CDCl3) d 200.1, 160.3, 148.4, 148.2, 126.9, 126.0, 122.5, 120.5,
111.2, 60.5, 52.3, 45.5, 37.9, 35.5, 30.2, 29.8, 27.8, 25.9, 18.3,
12.1, 25.5. Anal. calcd C 73.36, H 9.23, N 3.29; found C 73.27,
H 9.27, N 3.25.
3-[N-Ethyl-N-2-(tert-butyldimethylsiloxy)ethyl]aniline-4-yl-1-
dicyanomethylidene-2-cyclohexene (6d). The general method
for the Knoevenagel-type condensation was used with 5d
1
(1.77 g, 4.7 mmol). Red oil, yield 1.07 g (2.5 mmol, 54%). H
NMR (300 MHz, CDCl3) d 7.57 (d, J ~ 9.2 Hz, 2H, CH); 7.14
(s, 1H, CH); 6.68 (d, J ~ 9.1 Hz, 2H, CH); 3.79 (t, J ~ 6.1 Hz,
2H, OCH2); 3.49–3.53 (m, 4H, NCH2); 2.74–2.78 (m, 4H,
CH2); 1.97 (q, J ~ 6.3 Hz, 2H, CH2); 1.20 (t, J ~ 7.1 Hz, 3H,
CH3); 0.88 (s, 9H, CH3); 0.31 (s, 6H, CH3). 13C NMR (75 MHz,
CDCl3) d 170.8, 158.4, 150.9, 129.1, 124.3, 116.5, 115.1, 114.3,
112.0, 74.5, 61.0, 52.9, 46.3, 29.8, 28.0, 26.4, 22.2, 18.8,
12.7, 24.8. The compound was deprotected without further
characterization.
General procedure for Knoevenagel-type condensation of ketones
5a–d, 7b and 9a–d with malonodinitrile
The ketones (5a–d, 7b and 9a–d) were dissolved in the
minimum amount of refluxing ethanol. Six equivalents of
malonodinitrile were added, along with a catalytic amount of
piperidine. The reaction mixture was stirred at 70 uC for 1–2 h.
The conversion of the starting material was monitored by
TLC. The reaction was stopped when a side product was
observed. The solvent was evaporated and the dark residue was
purified by column chromatography on silica gel with a mixture
of hexane and ethyl acetate as eluent. The resulting colored
solids were recrystallized from ethanol. The reactions were
carried out on scales of 1.0–7.3 mmol of the ketones.
3-(N-Ethyl-N-2-hydroxyethyl)anilin-4-yl-1-dicyanomethylidene-
2-cyclohexene (6e). A mixture of 580 mg (1.4 mmol) 6d, 13 mL
acetic acid, 5 mL tetrahydrofuran and 5 mL water was stirred
at 50u for 48 h. The red solution was poured into saturated
aqueous sodium chloride solution and extracted three times
with dichloromethane. The combined organic layers were
washed with saturated aqueous sodium bicarbonate solution,
dried over sodium sulfate and evaporated. The resulting red oil
was chromatographed over silica gel, using ethyl acetate :
cyclohexane 1 : 1 as eluent. The eluent was further changed to
ethyl acetate : cyclohexane 2 : 1, to yield the crude alcohol,
which was recrystallized from ethanol to give 266 mg (0.9 mmol,
63%) red crystals (mp.: 125–127 uC). 1H NMR (300 MHz,
CDCl3) d 7.56 (d, J ~ 9.0 Hz, 2H, CH); 7.11 (s, 1H, CH); 6.73
(d, J ~ 8.3 Hz, 2H, CH); 3.83 (q, J ~ 5.3 Hz, 2H, OCH2);
3.46–3.57 (m, 4H, NCH2); 2.75 (t, J ~ 6.3 Hz, 4H, CH2); 1.95
(quint, J~6.3Hz, 2H, CH2); 1.56 (s, 1H, OH); 1.19 (t, J~7.0Hz,
3-(N,N-Di-n-butylaniline-4-yl)-1-dicyanomethylidene-2-cyclo-
hexene (6a). The general method for the Knoevenagel-type
condensation was used with 5a (2.60 g, 8.7 mmol). Red needles,
yield 1.66 g (4.8 mmol, 55%), mp. 101–102 uC. 1H NMR
(300 MHz, CDCl3) d 7.56 (d, J ~ 9.1 Hz, 2H, CH): 7.12 (s, 1H,
CH); 6.61 (d, J ~ 9.1 Hz, 2H, CH); 3.32 (t, J ~ 7.6 Hz, 4H,
NCH2); 2.75 (t, J ~ 6.4 Hz, 4H, CH2); 1.95 (quint., J ~ 6.3 Hz,
J. Mater. Chem., 2003, 13, 825–833
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3H, CH3). 13C NMR (75 MHz, CDCl3) d 170.1, 157.6,
150.4, 128.4, 116.6, 114.3, 113.5, 112.0, 111.5, 74.2, 60.1, 52.5,
45.9, 29.2, 27.5, 21.6, 11.9. UV-vis (CH2Cl2): lmax ~ 471 nm, e
(471) ~ 4.2 6 104 M21 cm21. HRMS: calculated m/z 308.1763
(MH1); found m/z 308.1772 (MH1). Anal. calcd. C 74.24, H
6.89, N 13.67; found C 73.96, H 6.94, N 13.47.
120.8, 120.3, 114.4, 113.7, 74.9, 36.0, 35.3, 33.9, 29.9, 29.8, 29.0,
28.2, 22.7, 14.2 (2C overlapping in aromatic region). UV
(CH2Cl2): lmax ~ 497 nm; e (497) ~ 3.8 6 104 M21cm21. Anal.
calcd C 82.58, H 7.45, N 7.22; found C 82.41, H 7.46, N 7.31.
7-[N-Ethyl-N-2(tert-butyldimethylsiloxyethyl)anilin-4-yl]-
2-dicyanomethylidene-4,4a,5,6-tetrahydro-3H-naphthalene (10d).
The general method for the Knoevenagel-type condensation
was used with 9d (858 mg, 2.02 mmol). Dark red solid, yield
5,5-Dimethyl-3-[N,N-bis(4-n-butylphenyl)aniline-4-yl]-1-dicyano-
methylidene-2-cyclohexene (8b). The general method for the
Knoevenagel-type condensation was used with 7b (900 mg,
1.87 mmol). Red solid, yield 335 mg (0.63 mmol 34%), mp.
127–129 uC. 1H NMR (300 MHz, CD2Cl2) d 7.51 (d, J ~
8.9 Hz, 2H, CH); 7.16 (d, J ~ 8.3 Hz, 4H, CH); 7.12 (s, 1H,
CH); 7.06 (d, J ~ 8.3 Hz, 4H, CH); 6.94 (d, J ~ 8.9 Hz, 2H,
CH); 2.62–2.57 (m, 8H, CH2); 1.62 (m, 4H, CH2); 1.33 (sext,
J ~ 7.4 Hz, 4H, CH2); 1.07 (s, 6H, CH3); 0.94 (t, J ~ 7.3 Hz,
6H, CH3). 13C NMR (75 MHz, CDCl3) d 169.5, 155.6, 151.1,
143.9, 139.5, 129.5, 129.0, 127.6, 125.8, 119.7, 117.0, 114.0,
113.1, 77.8, 42.7, 41.9, 35.1, 33.6, 32.2, 28.0, 22.4, 13.9. UV-vis
1
678 mg (1.4 mmol, 71%). H NMR (300 MHz, CDCl3) d 7.46
(d, J ~ 9.0 Hz, 2H, CH); 6.66–6.69 (m, 3H, CH); 6.57 (s, 1H,
CH); 3.76 (t, J ~ 6.2 Hz, 2H, OCH2); 3.42–3.49 (m, 4H,
NCH2); 2.85–3.06 (m, 2H, CH2); 2.45–2.61 (m, 3H, CH&CH2);
2.05–2.09 (m, 2H, CH2); 1.46–1.53 (m, 2H, CH2); 1.17 (t, J ~
7.0 Hz, 3H, CH3); 0.87 (s, 9H, CH3); 0.02 (s, 6H, CH3). 13C
NMR (75 MHz, CDCl3) d 169.9, 159.5, 151.7, 127.4, 120.8,
120.7, 120.6, 119.2, 114.6, 111.6, 111.4, 74.2, 60.5, 52.4, 45.7,
35.8, 29.6, 29.5, 28.7, 27.7, 25.9, 18.3, 12.1, 25.4. Compound
deprotected without further characterization.
(CH2Cl2): lmax ~ 482 nm; e (482) ~ 3.8 6 104 M21cm21
.
Anal. calcd C 84.12, H 7.46, N 8.40; found C 84.05, H 7.46, N 8.42.
7-[N-Ethyl-N-(2-hydroxyethyl)anilin-4-yl]-2-dicyanomethylidene-
4,4a,5,6-tetrahydro-3H-naphthalene (10e). 678 mg (1.4 mmol)
of 10d were stirred for 15 h at 50 uC with 13 mL acetic acid,
5 mL tetrahydrofuran and 5 mL water. The mixture was
diluted with water and extracted with dichloromethane. The
combined organic layers were washed with saturated aqueous
sodium bicarbonate solution, dried over sodium sulfate and
evaporated. The resulting crude solid (480 mg, 1.3 mmol, 95%)
was recrystallized from EtOH, yielding 360 mg (1 mmol, 70%)
purple–black crystals (mp.: 181–184 uC). 1H NMR (300 MHz,
CDCl3) d 7.47 (d, J ~ 9.0 Hz, CH); 6.73 (d, J ~ 9.0 Hz, 2H,
CH); 6.71 (s, 1H, CH); 6.57 (s, 1H, CH); 3.79–3.85 (m, 2H,
OCH2); 3.44–3.55 (m, 4H, NCH2); 3.01–3.05 (m, 1H, CH2);
2.84–2.91 (m, 1H, CH2); 2.41–2.68 (m, 3H, CH&CH2); 2.03–
2.10 (m, 2H, CH2); 1.57 (br, 1H, OH); 1.21–1.52 (m, 2H, CH2);
1.18 (t, J ~ 7.0 Hz, 3H, CH3). 13C NMR (75 MHz, CDCl3) d
169.9, 159.4, 151.5, 149.3, 127.3, 125.8, 120.6, 119.3, 114.5,
113.7, 111.8, 73.6, 60.2, 52.3, 45.6, 35.6, 29.6, 29.5, 28.7, 27.8,
7-[(N,N-Di-n-butyl)aniline-4-yl]-2-dicyanomethylidene-4,4a,5,6-
tetrahydro-3H-naphthalene (10a). The general method for the
Knoevenagel-type condensation was used with 9a (1.14 g,
3.0 mmol). Purple needles, yield 1.09 g, (2.7 mmol, 84%), mp.
124–126 uC. 1H NMR (300 MHz, CDCl3) d 7.46 (d, J ~ 9.0 Hz,
2H, CH); 6.68 (s, 1H, CH); 6.60 (d, J ~ 8.9 Hz, 2H, CH); 6.56
(s, 1H, CH); 3.30 (t, J ~ 7.6 Hz, 4H, CH2N); 2.99–3.06 (m, 1H,
CH2); 2.85–2.92 (m, 1H, CH2); 2.41–2.66 (m, 3H, CH2 & CH);
2.03–2.09 (m, 2H, CH2); 1.42–1.62 (m, 6H, CH2); 1.35 (sext,
J ~ 7.3 Hz, 4H, CH2); 0.95 (t, J ~ 7.2 Hz, 6H, CH3). 13C
NMR (75 MHz, CDCl3) d 169.9, 159.7, 151.9, 149.3, 127.4,
124.6, 120.1, 119.0, 114.7, 114.0, 111.2, 72.8, 50.7, 35.8, 29.6,
29.5, 29.4, 28.8, 27.7, 20.3, 14.0. UV-vis (CH2Cl2): lmax
~
519 nm, e (519) ~ 5.2 6 104 M21 cm21. HRMS: calcd m/z
399.2674; found m/z 399.2670. Anal. calcd C 81.16, H 8.32,
N 10.52; found C 81.14, H 8.34, N 10.44.
11.8. UV(CH2Cl2):lmax ~502nm;e(502)~4.66104M21 cm21
.
7-[N,N-Bis(4-n-butylphenyl)aniline-4-yl]-2-dicyanomethylidene-
4,4a,5,6-tetrahydro-3H-naphthalene (10b). The general method
for the Knoevenagel-type condensation was used was used
with 9b (500 mg, 1.0 mmol). Dark red leaflets, yield 386 mg
(0.70 mmol, 70%), mp. 131–134 uC. 1H NMR (300 MHz,
CDCl3) d 7.38 (d, J ~ 8.8 Hz, 2H, CH): 7.09 (d, J ~ 8.4 Hz,
4H, CH); 7.01 (d, J ~ 8.6 Hz, 4H, CH); 6.95 (d, J ~ 8.9 Hz,
2H, CH); 6.60 (s, 1H, CH); 6.69 (s, 1H, CH); 3.01–3.09 (m, 1H,
CH2); 2.81–2.87 (m, 1H, CH2); 2.42–2.69 (m, 6H, CH2); 2.06–
2.12 (m, 2H, CH2); 1.44–1.64 (m, 7H, CH2); 1.38 (sext., J ~
7.4 Hz, 4H, CH2); 0.92 (t, J ~ 7.3 Hz, 6H, CH3). 13C NMR
(75 MHz, CDCl3) d 169.9, 158.8, 151.0, 149.7, 144.3, 138.9,
130.4, 129.4, 126.6, 125.4, 122.3, 120.5, 120.0, 114.2, 113.5,
74.5, 35.7, 35.0, 33.6, 29.6, 29.5, 28.7, 27.9, 22.4, 14.0. UV
HRMS calcd m/z 359.1998; found m/z 359.2012.
Acknowledgements
The work in this paper was sponsored by the Ballistic Missile
Defense Organization, Innovative Science and Technology
Office, National Science Foundation and the Air Force Office
of Scientific Research.
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