The first hexagonal columnar discotic liquid crystalline carbazole derivatives induced by noncovalent π-π interactions

Article abstract of DOI:10.1039/b103052n

The synthesis of 13 discotic mesogens is described in which the well-known hexakis(pentyloxy)triphenylene liquid crystalline material has been chemically modified to incorporate one, two, three and six carbazole moieties. These modifications have been achieved by the alkylation or esterification of mono-, di-, tri- and hexa-hydroxytriphenylene derivatives with alkyl bromides and carboxylic acids incorporating the carbazole moiety. The pure compounds are not liquid crystalline in nature but when doped with TNF, hexagonal columnar mesophases are induced, as shown by DSC, OPM and X-ray diffraction. These mesophases exist below room temperature. The mesophase clearing temperatures are dependent on several factors including the chain length separating the carbazole moiety from the triphenylene core, and the nature of the ether or ester linkage, and the degree of TNF doping. The data suggest that the most stable mesophases (highest clearing temperatures) are formed when a 2:1 complex is formed between the carbazole derivatives and the TNF, respectively. The correlation length obtained from X-ray diffraction reveals that the columnar order for one of the ether derivatives decreases, whereas the correlation length increases for one of the ester derivatives. This result suggests that the TNF is not only partaking in π-π noncovalent bonding interactions, but also in polar interactions with the C=O bond. Such mesogenic carbazole derivatives may have advantageous photorefractive properties over the amorphous polymeric materials.

Full text of DOI:10.1039/b103052n

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The first hexagonal columnar discotic liquid crystalline carbazole
derivatives induced by noncovalent p–p interactions{{
M. Manickam,a Maura Belloni,a Sandeep Kumar,b Sanjay K. Varshney,b D. S. Shankar Rao,b
Peter R. Ashton,a Jon A. Preece*a and Neil Spencera
aSchool of Chemistry, University of Birmingham, Edgbaston, Birmingham, UK B15 2TT.
E-mail: j.a.preece@bham.ac.uk
bCentre for Liquid Crystal Research, P.O. Box 1329, Jalahalli Bangalore–560 013, India
Received 4th April 2001, Accepted 22nd June 2001
First published as an Advance Article on the web 1st October 2001
The synthesis of 13 discotic mesogens is described in which the well-known hexakis(pentyloxy)triphenylene
liquid crystalline material has been chemically modified to incorporate one, two, three and six carbazole
moieties. These modifications have been achieved by the alkylation or esterification of mono-, di-, tri- and
hexa-hydroxytriphenylene derivatives with alkyl bromides and carboxylic acids incorporating the carbazole
moiety. The pure compounds are not liquid crystalline in nature but when doped with TNF, hexagonal
columnar mesophases are induced, as shown by DSC, OPM and X-ray diffraction. These mesophases exist
below room temperature. The mesophase clearing temperatures are dependent on several factors including the
chain length separating the carbazole moiety from the triphenylene core, and the nature of the ether or ester
linkage, and the degree of TNF doping. The data suggest that the most stable mesophases (highest clearing
temperatures) are formed when a 2 : 1 complex is formed between the carbazole derivatives and the TNF,
respectively. The correlation length obtained from X-ray diffraction reveals that the columnar order for one of
the ether derivatives decreases, whereas the correlation length increases for one of the ester derivatives. This
result suggests that the TNF is not only partaking in p–p noncovalent bonding interactions, but also in polar
interactions with the CLO bond. Such mesogenic carbazole derivatives may have advantageous photorefractive
properties over the amorphous polymeric materials.
few examples in which the carbazole moiety has been
1. Introduction
incorporated into thermotropic low molecular weight and
polymeric liquid12 crystalline materials and into lyotropic
liquid crystals.13 Furthermore, as far as we are aware, there are
no examples of low molecular weight thermotropic hexagonal
columnar discotic liquid crystals which incorporate the
carbazole. Thus, one of the approaches that we are adopting14
to induce hexagonal columnar discotic mesophases in carba-
zole derivatives is the covalent modification of the carbazole
moiety with the well-known15 discotic triphenylene derivatives.
Here we report (i) the synthesis of several carbazole
triphenylene hybrid structures in which one (1a–e), two
(2a–b), three (3a–b and 4a–b) and six (5a–b) carbazole units
are covalently linked to the periphery of the triphenylene core
and (ii) the induced mesophase behaviour of some of these
carbazole derivatives when ‘‘complexed’’ with trinitrofluor-
enone (TNF).16 The chemical structures of the carbazole
derivatives are shown in Fig. 1.
Due to their extensive biological activity carbazole derivatives
and their chemistry have been studied at length.1 However, it is
only recently that they have been studied in terms of their
material properties1,2 and in particular their photorefractive
properties.3 The interest in photorefractive materials4 lies in
their numerous potential technological applications,5 such as
high density optical data storage, optical image processing,
phase conjugated mirrors, dynamic holography, optical
computing, parallel optical logic, and pattern recognition.
Thus, recent studies on carbazole materials have been
concerned with electroluminescence,6 nonlinear optics,7 and
photoconductivity.8 Amorphous organic photorefractive mate-
rials9 have many advantages over crystalline inorganic3 and
latterly crystalline organic10 photorefactive materials on which
the early research was carried out. These advantages include
large optical nonlinearities, low relative permittivities, low cost,
structural flexibilty, and ease of fabrication. However, the
major drawback of the amorphous organic photorefractive
materials is that a low Tg is required in order that the material
can be aligned by a dc electric field to induce a degree of
anisotropic ordering.11 The chemical modification of the
carbazole moiety to induce liquid crystallinity is attractive in
order to combine the advantages of the amorphous materials
with anisotropic ordering. However, to date there are only a
2. Results and discussion
2.1 Synthesis
The synthesis (Scheme 1) of the mono-, bis- and tris-carbazole
derivatives relies upon the mono-, bis- and tris-dealkylation of
the parent hexakis(pentyloxy)triphenylene 6a (R ~ C5H11)
with bromocatecholborane17 to afford the monohydroxy 7, the
dihydroxy 8, the C3 symmetrical trihydroxy derivative 9 and
the asymmetrical trihydroxy derivative 10. The hexahydroxy
derivative 11 is prepared by a full demethylation of hexa-
methoxytriphenylene 6b (R ~ CH3)18 The hexakis(alkyloxy)tri-
phenylenes 6a and 6b are synthesised via a trimerisation of the
corresponding 1,2-dialkoxybenzene derivatives with FeCl3.19
{Basis of a presentation given at Materials Discussion No. 4, 11–14
September 2001, Grasmere, UK.
{Electronic supplementary information (ESI) available: tables of
reagents and conditions for the synthesis of 1b, 2a, 3a, 4a, 5a, 1d, 1e,
2b, 3b, 4b, 12b, 13a, 13b and 13c. See http://www.rsc.org/suppdata/jm/
b1/b103052n/
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DOI: 10.1039/b103052n

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Fig. 1 Molecular structures of the carbazole derivatives studied in this paper.
The N-alkylation20a of carbazole with 1,6-dibromohexane
or 1,8-dibromooctane affords the alkyl bromides 12a and 12b
(Scheme 2) which are then carried forward in O-alkylation
reactions of the hydroxytriphenylene derivatives 7–11 to
afford the ether linked derivatives 1a, 1b, 2a, 3a, 4a and 5a.
N-Alkylation20b of the carbazole with methyl 4-bromobutano-
ate, methyl 6-bromohexanoate, and methyl 8-bromooctanoate
afforded the three esters 13a–c. These esters were subsequently
hydrolysed to the carboxylic acids 14a–c (Scheme 2). The
acids 14a–c were then coupled to the hydroxytriphenylene
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Scheme 1 Synthetic routes to the hydroxytriphenylene derivatives 7–11.
derivatives 7–10 using DCC–DMAP to afford the ester linked
carbazole derivatives 1c, 1d, 1e, 2b, 3b, and 4b (Scheme 3). The
synthesis of 5b required a slightly different route than was
required for the less substituted esters, because of the poorer
solubility of the hexahydroxy derivative 11. Thus, 11 was
coupled with the acid chloride 15b (prepared from the acid 14b
and thionyl chloride). The synthesis of 12 was also accom-
panied by the isolation of 12a.dimer as a minor by-product.
phase changes as they were heated at 10 uC min21 and finally
yielding the isotropic liquid. Tables 1 and 2 (first entry)
highlight the melting behaviour of the pure derivatives 1–5.
Optical polarised microscopy (OPM) confirmed our obser-
vations from DSC and none of the materials were birefringent
liquids.
2.3 Phase behaviour of binary mixtures of the carbazole
derivatives and trinitrofluorenone as a function of temperature
2.2 Phase behaviour of the carbazole derivatives as a function of
temperature
Undeterred by the lack of liquid crystallinity displayed by the
carbazole derivatives, we set about investigating whether it was
possible to induce liquid crystalline behaviour by the formation
of binary mixtures of the carbazole derivatives with TNF,
which has been shown16 to induce liquid crystalline behaviour
in other disc-shaped materials which alone do not display
The differential scanning calorimetric (DSC) analysis of
compounds 1–4 revealed that none of the materials possessed
liquid crystalline behaviour, and were either crystalline or
amorphous materials which underwent various solid–solid
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Scheme 2 Synthetic routes to the carbazole derivatives 12a–b, 14a–c and 15b used in the coupling with 7–11.
mesophases. Initial screening was performed by variable
temperature optical polarised microscopy by contact prepara-
tion of the carbazole materials with TNF. This revealed that for
the monocarbazole derivatives 1a–d, a mesophase could be
induced at the boundary between the molten materials (Fig. 2
illustrates the OPM picture for 1c–TNF contact preparation).
Induction of mesophases could also be achieved for the bis-
carbazole derivatives 2a and 2b. However, none of the higher
substituted derivatives (3–5) displayed a mesophase with TNF
by contact preparation.
A quantitative investigation of the mesophase behaviour of
1a–e, 2a and 2b as function of the mol% of TNF in the binary
mixtures is tabulated in Tables 1 and 2, whilst Fig. 3
graphically illustrates these data for compounds 1a–e. Fig. 4
illustrates the mesophase textures of 1a with various doping
concentrations of TNF. All of the mesophase textures were
indicative of a Colh ordering, displaying droplets with linear
defects as well as homeotropic star-shaped domains with
hexagonal symmetry domains which developed into a mosaic
texture upon cooling from the isotropic melt.21 The Colh
structure was confirmed by X-ray diffraction experiments (see
later). The doped samples were prepared from a solution of the
colourless carbazole derivative16 with the appropriate equiva-
lent of the pale yellow solutions of TNF followed by
concentration in vacuo to leave dark brown residues which
were further rigorously dried on a vacuum line. Upon heating,
these samples passed directly from the solid state into the
isotropic liquid state. However, upon cooling they passed from
the isotropic liquid state to a birefrigent liquid state whose
textures were indicative of hexagonal columnar mesophases.
These phase changes were confirmed by X-ray crystallography.
All of the mesophases persisted down to room temperature,
and the mesophases even survived storage in the fridge for two
hours without crystallisation. Mixtures containing more than
Scheme 3 Synthetic routes to target carbazole derivatives 1–5.
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Table 1 Phase behaviour of binary mixtures of the carbazole derivatives 1a–e and TNF as a function of temperature as determined by optical
polarising microscopy and X-ray analysis
Phase behaviour
TNF/mol%
1a
1b
1c
1d
1e
0.0
2.3
4.9
9.5
16.6
23.1
32.9
41.1
50.0
66.8
K 106 uC I
K 81 uC I
K 72 uC I
K 77 uC I
K 99 uC I
K 78 uC I
K 95 uC I
K 98 uC I
K 70 uC I
—
I 90 uC Colh
I 116 uC Colh
I 115 uC Colh
I 70 uC Colh
K 99 uC I
K 73 uC I
K 79 uC I
K 62 uC I
K 74 uC I
K 80 uC I
K 71 uC I
I 110 uCa Colh
I 142 uC Colh
—
I 185 uC Colh
I 190 uC Colh
I 189 uC Colh
I 179 uC Colh
K 70 uC I
I 77 uCa Colh
I 96 uC Colh
—
I 150 uC Colh
I 153 uC Colh
I 152 uC Colh
I 111 uC Colh
K 107 uC I
K 80 uC I
I 82 uC Colh
I 130 uC Colh
I 144 uC Colh
I 150 uC Colh
I 139 uC Colh
K 147 uC I
I 66 uC Colh
I 99 uC Colh
I 113 uC Colh
I 114 uC Colh
I 96 uC Colh
K 145 uC I
aThe mesophase texture was not very well-defined at this mol% of TNF.
Table 2 Phase behaviour of the carbazole derivatives 2–5 as a function of temperature and doping 1 : 1 with TNF as determined by optical polarising
microscopy
Phase behaviour
TNF/
mol% 2a
2b
3a
3b
4a
4b
5a
5b
0
50
K 114 uC I
K 147 uC I
K 132 uC I
K 106 uC I
K 122 uC I
K 104 uC I
K 89 uC I
K 290 uC (dec)
I 90 uC Colh I 112 uC Colh No mesophasea No mesophasea No mesophasea No mesophasea No mesophasea No mesophasea
aAs determined by contact preparation.
50 mol% TNF are thermodynamically unstable due to phase
separation by crystallization of TNF.
complex’’ in which each p-electron deficient TNF molecule is
sandwiched between two p-electron rich triphenylene–carbazole
moieties.
Detailed analysis of Tables 1 and 2 and Fig. 3 reveals that:
(a) for both the ether linked samples 1a and 1b and the ester
linked samples 1c–e, an increase in the length of the spacer
between the triphenylene moiety and the carbazole unit reduces
the isotropization temperature (Fig. 3a); (b) the replacement of
the methylene unit for the carbonyl unit when comparing 1a
with 1d (C6 chains), and 1b with 1e (C8 chains): (i) has little
effect of the isotropization temperatures in the range between
23.1 to 41.1 mol% of TNF (the largest difference is 20 uC for
23.1 mol% doping when comparing 1a and 1d, and all other
differences in the range are 10 uC or less) (Fig. 3b), (ii) increases
the doping concentration over which the mesophases are
observed when comparing 1b and 1e, but decreases when
comparing 1a and 1d (Fig. 3b), and (iii) results in a reversal in
the clearing temperature sequence for the highest TNF doping
concentration (50 mol %) at which the mesophases were
observed such that 1a and 1b have the higher clearing tem-
perature (Fig. 3b) relative to 1d and 1e, respectively; (c) the
highest clearing temperature is observed in every case in the
region of 30–40 mol% TNF, which is suggestive of a ‘‘2 : 1
Thus, it can be summarised that chain length governs
isotropization of the mesophases, whilst the nature of the
linking group (ether, -OCH2-, or ester, -OC(O)-) governs
the range of concentrations with which TNF can induce the
mesophases, with a maximum stabilisation indicative of a 2 : 1
complex structure. We speculate here that the more polar ester
functionality in 1c and 1d interacts with the polar TNF moiety
in such a way that at lower concentrations of TNF doping, the
TNF is intercalated more easily between the electron rich
p-units of the triphenylene moieties and/or the carbazole units
and in turn induces the mesophase at lower concentrations,
relative to the less polar ether linked derivatives 1a and 1b.
2.4 UV Analysis
In order to ascertain with which p-donor unit (carbazole or
triphenylene) the TNF forms the charge-transfer complex,
solution state UV/Vis experiments were carried out with 1a, the
carbazole derivative 12a, hexakis(pentyloxy)triphenylene deri-
vative 6a and TNF. The UV/Vis spectra of the 1 : 1 mixtures
(1022 M) of 1a, 12a, and 6a with TNF revealed that there was
only a small CT band associated with the carbazole 12a–TNF
interaction, with a lmax at 450 nm (e ~ 75 M21 cm21), whereas
with 6a–TNF there was a much stronger band at a lmax onset at
620 nm (e ~ 300 M21 cm21). Thus, it was not unexpected that
the CT band of 1a with TNF resembled that of 6a–TNF with
the lmax onset at 570 nm (e ~ 250 M21 cm21). Thus, it was
concluded that in solution the CT complex between 1a and
TNF results primarily from the triphenylene moiety–TNF
interaction. This conclusion was extrapolated to the condensed
phase by the visual appearance of the binary materials, which
resembled the colours of the solutions.
2.5 X-Ray diffraction
X-Ray diffraction experiments have been carried out on two
compounds (1b and 1c) as complex mixtures with 32.9 mol%
and 50 mol% TNF) at 30 uC and 100 uC in their mesophase
Fig. 2 Optical polarising micrograph of contact preparation experi-
ment of 1c and TNF.
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Fig. 3 (a) Graphical representation of the monotropic behaviour of the ether linked carbazole derivatives 1a and 1b as binary mixtures with varying
concentrations of TNF, and the ester linked carbazole derivatives 1c–e as binary mixtures with varying concentrations of TNF as they enter the
hexagonal columnar mesophase from the isotropic liquid. (b) Graphical representation to compare and contrast the thermal behaviour of the Colh
mesophases as a function of the ether linkage and the ester linkage for the carbazole units separated by C6 (1a and 1d) chains and C8 (1b and 1e)
chains from the triphenylene moieties.
Fig. 4 Optical polarising micrographs of 1a with TNF in the Colh mesophase (a) 2.3 mol%, (b) 9.5 mol%, (c) 32.9 mol%, and (d) 41.1 mol% of TNF.
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Table 3 X-Ray diffraction data for compounds 1b and 1c with 32.9 mol% and 50 mol% TNF in the Colh mesophase at 30 uC and 50 uC, and 30 uC
and 100 uC, respectively
d-Spacings/nm
Columnar
spacing/nm
Correlation
length/nm
Compound
TNF/mol%
Temp./ uC
d100
dcore–core
dalkyl
1b
1b
1b
1b
1c
1c
1c
1c
32.9
50.0
32.9
50.0
32.9
50.0
32.9
50.0
30
30
50
50
30
30
100
100
1.86
1.74
1.86
1.75
1.79
1.71
1.81
1.74
0.339
0.336
0.340
0.336
0.339
0.337
0.343
0.340
0.434
0.430
0.438
0.434
0.432
0.429
0.444
0.438
2.14
2.01
2.14
2.02
2.07
1.97
2.09
2.01
13.39
13.10
11.80
10.68
12.09
14.26
10.47
11.47
ranges, the results of which are shown in Table 3. The features
of the diffractograms for all combinations of molar ratio and
temperature were similar. As a representative example, we
describe in detail the case for 1c at 100 uC in a 1 : 1 ratio with
TNF. The diffraction pattern (Fig. 5a) and the derived one-
dimensional intensity versus 2h profile (Fig. 5b) obtained by
integrating over the entire x (0–360u) range at 100 uC, are
consistent with the structure of a Colh mesophase. In the low
angle region, four sharp peaks (one strong and three weak
reflections) are observed whose d-spacings are in the ratio
1 : 1d3, 1 : 1d4, and 1 : 1d7. Indentifying the first peak with the
Miller index (100), the ratios conform to the expected values
from a two-dimensional hexagonal lattice. In the wide angle
region, two diffuse reflections are observed. The broad one
corresponds to the liquid-like ordering of the aliphatic chains,
whilst the relatively sharper one, observed at higher 2h values
and well separated from the broad one, is due to the stacking of
the triphenylene cores in a columnar fashion. Similar features
were observed for the scans taken at 30 uC.
100 uC. These results are indicative of increased core–core
interactions in the columns as the mole ratio of TNF is
increased in the binary mixtures. Additionally, the core–core
separation was found to be weakly temperature dependent,
such that at higher temperatures, the separation increased as
would be expected.
However, an unusual result from the X-ray analysis is
depicted in Fig. 6. The results for the ester 1c are as expected,
i.e. as the mol% of TNF increases, the correlation length
increases at both 30 uC and 100 uC, suggesting closely packed
columnar structure. However, although the core–core separa-
tion decreases with increasing mol% of TNF for the ether 1b,
the correlation length decreases at both temperatures. Thus,
the polar CLO bond in the ester derivative must also be playing
an important role in the stabilisation of the mesophase. This
conclusion fits with a recent study of mixed ether–ester tri-
phenylene derivatives which have shown higher correlation
length compared to pure triphenylene ethers.22
For all substances studied, the core–core separation at 30 uC
was in the range 0.336–0.340 nm. These values are about
0.02 nm shorter than those observed in undoped triphenylene
mesophases, but are comparable to the values for TNF doped
triphenylene mesophases. Thus, the core–core separation for
1b decreases from 0.339 nm (33 mol% TNF) to 0.336 nm
(50 mol% TNF) at 30 uC and from 0.340 nm to 0.336 nm at
3 Concluding remarks
The synthesis of several mesogenic carbazole derivatives has
been described. The pure compounds were found not to be
liquid crystalline in nature. However, by doping with TNF,
mesophases were induced with optical textures associated with
columnar ordering. These were subsequently confirmed by
X-ray diffraction as being Colh. The highest clearing points as a
function of TNF doping suggest that a 2 : 1 complex structure is
formed between the triphenylene–carbazole materials (1a–1e)
and the TNF, respectively. Liquid crystalline carbazole deri-
vatives are proposed as superior photorefractive materials to
the amorphous polymeric carbazole materials, as a conse-
quence of their inherent anisotropic ordering. Additionally,
the doping of the materials described here with TNF, is
advantageous and fortuitous, as it is reported11 that TNF
enhances the photorefractive properties of the polymeric
materials studied to date.11
Fig. 5 X-Ray diffraction data for 1c with 50 mol% of TNF at 100 uC;
(a) diffraction pattern, and (b) one dimensional intensity profile versus
2h.
Fig. 6 Plots of correlation lengths (from X-ray diffraction data) versus
mol ratio TNF for 1b and 1c at 30 uC and 100 uC.
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Currently, we are also synthesising and characterising various
series of mono-, tris-, and hexakis-functionalised carbazole
triphenylene derivatives and investigating their thermal beha-
viour also as CT complexes with TNF, as well as the introduc-
tion of the carbazole moiety into banana-shaped molecular
structures.23 These next generation materials are functionalised
to induce push–pull electronic systems for NLO behaviour,
photorefractive properties and ferroelectric switching.
extracted with Et2O (2 6 25 mL). The combined organic
extracts were dried (MgSO4), filtered, and the filtrate
evaporated to dryness under reduced pressure. The residue
was purified by silica gel column chromatograpy (eluent:
hexane–CH2Cl2, 1 : 3) to afford 1a (0.450 g, 66%) as a white
solid: 1H NMR (300 MHz, CDCl3, 21 uC): d ~ 0.95 (m, 15 H),
1.48 (m, 2 H), 1.92 (m, 14 H), 4.20 (m, 12 H), 4.35 (t,
J ~ 7.0 Hz, 2 H), 7.21 (m, 2 H), 7.44 (m, 4 H), 7.82 (m, 6 H),
8.09 (d, J ~ 7.7 Hz, 2 H); 13C NMR (75 MHz, CDCl3, 21 uC):
d ~ 14.0, 22.5, 26.0, 27.1, 28.8, 29.0, 29.1, 29.3, 43.0, 69.4, 69.6,
69.7, 69.8, 107.3, 107.4, 107.5, 107.6, 108.6, 118.9, 120.3, 122.8,
123.6, 123.7, 125.6, 140.4, 148.9, 149.0; MS (LSIMS): m/z 924
[M z H]z; elemental analysis calcd (%) for C61H81O6N: C
79.30, H 8.77, N 1.51; found C 79.30, H 8.58, N 1.46.
4 Experimental
General methods
Most of the reactions were carried out under a nitrogen
atmosphere. Chemicals were purchased from Aldrich and used
as received. Yields refer to chromatographically pure products.
Thin-layer Chromatography (TLC) was carried out on alumi-
nium sheets coated with silica gel 60 (Merck 5554 mesh).
Column chromatography was performed on silica gel 60
(Merck 230-400). Microanalyses were performed by the
University of London microanalytical laboratories or by the
University of Birmingham microanalytical services. Electron
impact (EI) mass spectra were recorded at 70eV on a VG
ProSpec mass spectrometer. Liquid secondary ion mass spectra
(LSIMS) were recorded on a VG ZabSpec mass spectrometer
equipped with a caesium ion source utilising m-nitrobenzyl
alcohol containing a trace of sodium acetate as the matrix.1H
NMR spectra were recorded on a Bruker AC 300 (300 MHz)
or a Bruker AMX400 (400 MHz) or a Bruker DRX500
(500 MHz) spectrometer.13C NMR spectra were recorded on a
Bruker AC300 (75.5 MHz) or a Bruker DRX500 (125.8 MHz)
spectrometer. The chemical shift values are expressed as d
values and the coupling constant values (J) are in hertz. The
following abbreviations are used for the signal multiplicities or
characteristics: s, singlet; d, doublet; dd, double doublet; t,
triplet; m, multiplet; q, quartet; quint; quintet; br, broad.
Transition temperatures were measured using a Mettler FP82
HT hot stage and central processor in conjunction with
Leitz DMFRT polarizing mircroscope as well as differential
scanning calorimetry (DSC7 Perkin-Elmer).
The same procedure for 1a was followed for the synthesis of
1b, 2a, 3a, 4a and 5a. (Quantities used for this set of reactions
are displayed in Table 1 of the supplementary material.{)
Compound 1b. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.05–1.00 (m, 15 H), 1.55–1.47 (m, 14 H), 1.65–1.57 (m,
14 H), 2.03–1.88 (m, 14 H), 4.29–4.23 (m, 14 H), 7.24 (br t,
J ~ 7.3 Hz, 2 H), 7.48 (br d, J ~ 7.2 Hz, 2 H), 7.47 (br t,
J ~ 7.7 Hz, 2 H), 7.89 (br s, 6 H), 8.12 (d, J ~ 7.7 Hz, 2 H);
13C NMR (125 MHz, CDCl3, 31 uC): d ~ 14.0, 22.5, 26.0, 27.2,
28.3, 28.9, 29.1, 29.3, 29.3, 29.4, 42.9, 69.7, 107.4, 108.5, 118.6,
120.2, 122.8, 123.6, 125.5, 140.3, 149.0; MS (LSIMS): m/z 952
[M z H]z; elemental analysis calcd (%) for C63H85NO6: C
79.49, H 8.93, N 1.47; found C 79.46, H 8.80, N 1.52.
Compound 2a. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.01–0.96 (q, J ~ 14.2, 7.2 Hz, 12 H), 1.56–1.43 (m, 6
H), 1.62–1.54 (m, 14 H), 1.69–1.63 (m, 4 H), 1.99–1.94 (m, 16
H), 4.26–4.21 (m, 12 H), 4.34 (t, J ~ 7.1 Hz, 4 H), 7.25–7.22
(m, 4 H), 7.48–7.42 (m, 8 H), 7.86 (br s, 6 H), 8.11 (d,
J ~ 7.6 Hz, 4 H); 13C NMR (125 MHz, CDCl3, 31 uC):
d ~ 14.0, 22.4, 22.5, 25.9, 27.0, 28.3, 28.9, 29.0, 29.1, 29.3,
42.8, 69.4, 69.6, 69.7, 107.3, 107.4, 107.5, 108.5, 118.7, 120.2,
122.8, 123.6, 125.5, 140.3, 148.9, 148.9, 149.0; MS (LSIMS):
m/z 1103 [M z H]z; elemental analysis calcd (%) for
C74H90N2O6: C 80.58, H 8.16, N 2.54; found C 79.86, H
8.11, N 2.65.
X-Ray studies were performed using an image plate detector
(MAC Science DIP 1030). Unoriented samples contained
in sealed Lindemann glass capillaries were irradiated with
CuKa rays obtained from a sealed-tube generator (Enraf-
Nonius FR590) in conjunction with double mirror focusing
optics. 2,3,6,7,10,11-Hexakis(pentyloxy)triphenylene (6a),19
2-hydroxy-3,6,7,10-pentakis(pentyloxy)triphenylene (7),17
hexamethoxytriphenylene (6b),18 2,7-dihydroxy-3,6,10,11-
tetrakis(pentyloxy)triphenylene (8),17 symmetrical 2,6,10-tri-
hydroxy-3,7,11-tris(pentyloxy)triphenylene (9)17 asymmetrical
2,7,10-trihydroxytris(pentyloxy)triphenylene (10),17 and hexa-
hydroxytriphenylene (11)18 were synthesized according to
literature procedures. The charge transfer complexes of the
carbazole triphenylene derivatives (1a–2b), with TNF were
prepared by dissolving the appropriate amount of both
compounds separately in CH2Cl2, mixing the solutions and
evaporating the solvent.24 X-Ray studies were performed using
an image plate detector (MAC Science DIP 1030) as described
previously.25
Compound 3a. 1H NMR (300 MHz, CDCl3, 21 uC): d ~ 0.9
(t, J ~ 7.3 Hz, 9 H), 1.53 (m, 24 H), 1.92 (m, 18 H), 4.15 (m, 12
H), 4.33 (t, J ~ 6.9 Hz, 6 H), 7.20 (m, 6 H), 7.42 (br s, 6 H),
7.43 (m, 6 H), 7.80 (br s, 6 H), 8.08 (d, J ~ 7.7 Hz, 6 H); 13C
NMR (75 MHz, CDCl3, 21 uC): d ~ 14.0, 22.4, 25.9, 27.1, 28.3,
28.9, 29.0, 29.3, 42.9, 69.4, 69.7, 107.4, 107.5, 108.5, 118.7,
120.3, 122.8, 123.6, 123.7, 125.5, 140.4, 148.9, 149.0; MS
(LSIMS): m/z 1283 [M z H]z; elemental analysis calcd (%)
for C87H99N3O6: C 81.42, H 7.72, N 3.26; found C 81.49, H
7.92, N 3.28.
Compound 4a. 1H NMR (500 MHz, CDCl3, 21 uC):
d ~ 0.94–0.89 (m, 9 H), 1.45–1.37 (m, 6 H), 1.55–1.47 (m, 12
H), 1.66–1.58 (m, 6 H), 1.97–1.84 (m, 18 H), 4.21–4.15 (m, 12
H), 4.33–4.28 (m, 6 H), 7.21–7.17 (m, 6 H), 7.44–7.37 (m, 12 H),
7.79 (br s, 2 H), 7.80 (br s, 2 H), 7.82 (br s, 2 H), 8.08–8.06 (m, 6
H); 13C NMR (125 MHz, CDCl3, 31 uC): d ~ 14.1, 22.5, 25.9,
27.1, 28.3, 28.9, 29.1, 29.3, 42.9, 69.4, 69.5, 69.6, 107.3, 107.4,
107.5, 107.6, 108.6, 118.7, 120.3, 122.8, 123.6, 123.7, 125.5,
140.4, 148.9, 149.0; MS (LSIMS); m/z 1283 [M z H]z;
elemental analysis calcd (%) for C87H99N3O6: C 81.42, H
7.72, N 3.26; found C 81.42, H 7.83, N 3.26.
Compound 1a
A solution of 2-hydroxy-3,6,7,10-pentakis(pentyloxy)triphen-
ylene 7 (0.50 g, 0.74 mmol) in DMSO (25 mL) was added to
K2CO3 (0.20 g, 1.48 mmol). The resultant slurry was stirred
and heated under reflux. A solution of bromocarbazole 12a
(0.29 g, 0.8 mmol) in DMSO (5 mL) was added dropwise over a
few minutes to the slurry, maintaining heating under reflux.
Heating was continued overnight. The reaction mixture was
cooled, H2O (20 mL) was added, and the reaction mixture was
Compound 5a. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.43–1.37 (m, 12 H), 1.57–1.51 (m, 12 H), 1.86–1.78 (m,
24 H), 4.11 (t, J ~ 12.6 Hz, 12 H), 4.2 (t, J ~ 14.3 Hz, 12 H),
7.16 (ddd, J ~ 7.83, 0.8, 1.0 Hz, 12 H), 7.03 (d, J ~ 8.1 Hz, 12
H), 7.39 (ddd, J ~ 8.1, 1.1, 1.1 Hz, 12 H), 7.76 (br s, 6 H), 8.04
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(d, J ~ 7.7 Hz, 12 H); 13C NMR (125 MHz, CDCl3, 31 uC):
d ~ 25.9, 27.0, 28.9, 29.3, 42.8, 69.4, 107.5, 108.6, 118.7, 120.3,
122.8, 123.7, 125.6, 140.4, 148.9; MS (LSIMS): m/z 1820
[M z H]z; elemental analysis calcd (%) for C126H126N6O6: C
83.16, H 6.93, N 4.62; found C 83.21, H 6.90, N 5.01.
127.8, 139.7, 140.3, 148.7, 148.9, 149.1, 149.3, 149.6, 171.7; IR
(Nujol): n ~ 1614, 1745 cm21 (CLO); MS (LSIMS): m/z 966
[M z H]z; elemental analysis calcd (%) for C63H83NO7: C
78.34, H 8.60, N 1.45; found C 78.43, H 8.59, N 1.65.
Compound 2b. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 0.99 (t, J ~ 7.2 Hz, 6 H), 1.0–1.2 (m, 6 H), 1.39–1.32
(m, 4 H), 1.50–1.52 (m, 8 H), 1.58–1.53 (m, 4 H), 1.87–1.81 (m,
4 H), 1.97–1.91 (m, 4 H), 2.44–2.38 (m, 4 H), 2.75 (t,
J ~ 7.0 Hz, 4 H), 4.23–4.19 (m, 8 H), 4.54 (t, J ~ 7.0 Hz, 4 H),
7.28–7.25 (m, 4 H), 7.53–7.47 (m, 8 H), 7.70 (br s, 2 H), 7.86 (br
s, 2 H), 8.04 (br s, 2 H), 8.14 (d, J ~ 7.7 Hz, 4 H); 13C NMR
(125 MHz, CDCl3, 31 uC): d ~ 13.9, 14.0, 22.3, 22.5, 24.1, 28.1,
28.3, 28.9, 29.0, 31.0, 41.9, 68.8, 69.1, 69.3, 69.4, 106.4, 106.6,
108.6, 116.7, 119.0, 120.4, 122.9, 124.1, 125.7, 127.4, 140.3,
149.2, 149.2, 171.1; IR (Nujol): n ~ 1620, 1752 cm21 (CLO);
MS (LSIMS): m/z 1075 [M z H]z; elemental analysis calcd
(%) for C70H78N2O8: C 78.21, H 7.26, N 2.60; found C 78.37, H
7.37, N 2.80.
Compound 1c
To
a solution of the carbazole derivative 14a (0.22 g,
0.89 mmol) in dry CH2Cl2 (10 mL), cooled to 0 uC under a
N2 atmosphere, was added 1,3-dicyclohexylcarbodiimide
(0.18 g, 0.89 mmol) and a catalytic amount of 4-dimethyl-
aminopyridine. The mixture was stirred for 30 minutes and
2-hydroxy-3,6,7,10-pentakis(pentyloxy)triphenylene 7 (0.50 g,
0.74 mmol) was added over 10 minutes, followed by further
stirring for 24 hours under a N2 atmosphere at room temp-
erature. The white precipitate was filtered and the filtrate was
diluted with CH2Cl2 (30 mL) and washed with H2O
(3 6 30 mL), followed by 10% NaHCO3 (10 mL) and brine
(5 mL). The organic phase was dried over (MgSO4), filtered,
and the filtrate evaporated to dryness under reduced pressure.
The residue was purified by silica gel column chromatography
(eluent: hexane–CH2Cl2, 1 : 3) to yield 1c (0.49 g, 73%) as a
Compound 3b. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 0.94 (t, J ~ 7.2 Hz, 9 H), 1.43–1.78 (m, 6 H), 1.50–1.45
(m, 6 H), 1.64–1.58 (m, 6 H), 1.85–1.79 (m, 6 H), 1.95–1.88 (m,
6 H), 2.03–1.97 (m, 6 H), 2.63 (t, J ~ 8.0 Hz, 6 H), 4.08 (t,
J ~ 6.8 Hz, 6 H), 4.34 (t, J ~ 7.1 Hz, 6 H), 7.28–7.23 (ddd,
J ~ 7.8 , 1.0, 0.9 Hz, 6 H), 7.51–7.48 (ddd, J ~ 7.0, 1.1, 1.0 Hz,
9 H), 7.44 (d, J ~ 8.1 Hz, 6 H), 7.86 (br s, 3 H), 8.13 (d,
J ~ 7.7 Hz, 6 H); 13C NMR (125 MHz, CDCl3, 31 uC):
d ~ 14.0, 22.5, 25.0, 26.8, 28.1, 28.7, 29.1, 34.0, 42.7, 68.1,
105.8, 108.5, 117.5, 118.8, 120.3, 122.0, 122.9, 125.6, 128.2,
139.1, 140.3, 149.3, 171.6; IR (Nujol): n ~ 1595, 1622,
1748 cm21 (CLO); MS (LSIMS): m/z 1324 [M z H]z;
elemental analysis calcd (%) for C87H93N3O9: C 78.91, H
7.02, N 3.17; found C 78.82, H 7.08, N 3.32.
1
white solid: H NMR (500 MHz, CDCl3, 31 uC): d ~ 0.91 (t,
J ~ 7.2 Hz, 6 H), 1.02–0.98 (m, 9 H), 1.41–1.34 (m, 2 H), 1.50–
1.45 (m, 10 H), 1.60–1.55 (m, 8 H), 1.88–1.82 (m, 6 H), 2.00–
1.95 (m, 4 H), 2.44–2.30 (m, 2 H), 2.76 (t, J ~ 7.0 Hz, 2 H),
4.25–4.21 (m, 10 H), 4.54 (t, J ~ 7.0 Hz, 2 H), 7.28–7.25 (m, 2
H), 7.53–7.48 (m, 4 H), 7.78 (br s, 1 H), 7.83 (br s, 2 H), 7.87 (br
s, 2 H), 8.06 (br s, 1 H), 8.14 (d, J ~ 7.7 Hz, 2 H); 13C NMR
(125 MHz, CDCl3, 31 uC): d ~ 3.9, 14.0, 22.3, 22.5, 24.1, 28.1,
28.3, 28.9, 29.0, 29.1, 31.0, 41.8, 68.7, 69.2, 69.4, 69.7, 69.8,
106.0, 106.6, 106.9, 107.3, 108.0, 108.6, 116.5, 118.9, 120.3,
122.9, 123.1, 123.2, 123.4, 124.6, 125.7, 128.0, 139.5, 140.3,
148.8, 149.0, 149.2, 149.7, 171.1; IR (Nujol): n ~ 1617 cm21
(CLO); MS (LSIMS): m/z 910 [M z H]z; elemental analysis
calcd (%) for C59H75NO7: C 77.88, H 8.25, N 1.54; found C
77.72, H 8.33, N 1.51.
Compound 4b. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.03–0.98 (m, 9 H), 1.49–1.43 (m, 6 H), 1.59–1.52 (m, 6
H), 1.66–1.59 (m, 6 H), 1.97–1.84 (m, 10 H), 2.05–1.99 (m, 8 H),
2.71–2.64 (m, 6 H), 4.22–4.13 (m, 6 H), 4.35 (ABq, J ~ 12.6,
6.9 Hz, 6 Hz), 7.32–7.29 (m, 6 H), 7.46 (br d, J ~ 8.1 Hz, 6 H),
7.53 (ddd, J ~ 8.1, 1.0, 1.0 Hz, 6 H), 7.61 (s, 1 H), 7.71 (s, 1 H),
7.73 (s, 1 H), 7.76 (s, 1 H), 7.79 (s, 1 H), 7.99 (s, 1 H), 8.16 (br d,
J ~ 0.7 Hz, 3 H), 8.18 (br d, J ~ 0.8 Hz, 3 H); 13C NMR
(125 MHz, CDCl3, 31 uC): d ~ 14.0, 22.4, 24.7, 26.7, 28.1, 28.2,
28.6, 28.9, 33.8, 42.6, 68.4, 68.5, 68.6, 105.7, 106.2, 106.3, 108.4,
116.3, 116.5, 117.1, 118.7, 120.2, 122.1, 122.7, 123.1, 123.3,
125.5, 126.9, 127.1, 128.0, 139.6, 140.0, 140.2, 149.2, 149.3,
149.6, 171.1, 171.2, 171.3; IR (Nujol): n ~ 1594, 1619,
1746 cm21 (CLO); MS (LSIMS); m/z 1324 [M z H]z;
elemental analysis calcd (%) for C87H93N3O9: C 78.91, H
7.02, N 3.17; found C 79.04, H 7.00, N 3.17.
The same procedure for 1c was followed for the synthesis of
1d, 1e, 2b, 3b and 4b. (Quantities used for these esterification
reactions are shown in Table 2 of the supplementary mate-
rial.{)
Compound 1d. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.50–1.40 (m, 15 H), 1.53–1.40 (m, 12 H), 1.63–1.55 (m,
12 H), 2.02–1.85 (m, 14 H), 2.66 (t, J ~ 7.4 Hz, 2 H), 4.22–4.17
(m, 10 H), 4.32 (t, J ~ 7.1 Hz, 1 H), 7.25 (ddd, J ~ 7.8, 0.8,
0.9 Hz, 2 H), 7.42 (d, J ~ 8.1 Hz, 2 H), 7.49 (ddd, J ~ 7.8, 0.8,
0.9 Hz, 2 H), 7.76 (br s, 1 H), 7.80 (br s, 2 H), 7.82 (br s, 1 H),
7.83 (br s, 1 H), 8.04 (br s, 1 H), 8.11 (d, J ~ 7.7 Hz, 2 H); 13
C
NMR (125 MHz, CDCl3, 31 uC): d ~ 14.0, 22.4, 22.5, 24.7,
26.7, 28.1, 28.3, 28.6, 28.9, 29.0, 29.1, 33.8, 42.6, 68.6, 69.1,
69.3, 69.6, 69.7, 105.9, 106.5, 106.8, 107.2, 107.9, 108.4, 116.5,
118.7, 120.2, 122.8, 122.9, 123.0, 123.1, 123.3, 124.5, 125.5,
127.8, 139.6, 140.3, 148.1, 148.8, 149.1, 149.2, 149.6, 171.5; IR
(Nujol): n ~ 1613 cm21 (CLO); MS (LSIMS): m/z 938
[M z H]z; elemental analysis calcd (%) for C61H79NO7: C
78.12, H 8.43, N 1.49; found C 78.31, H 8.54, N 1.36.
Compound 5b
Due to the insolubilty of this material in all common NMR
solvents it proved impossible to fully characterise this material.
IR (KBr): n ~ 1753 cm21 (CLO); MS (LSIMS); m/z 1904
[M z H]z.
Compound 12a
Compound 1e. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.05–0.98 (m, 15 H), 1.53–1.44 (m, 14 H), 1.65–1.58 (m,
12 H), 2.01–1.83 (m, 14 H), 2.68 (t, J ~ 7.5 Hz, 2 H), 4.32–4.19
(m, 12 H), 7.25 (br t, J ~ 7.4 Hz, 2 H), 7.42 (br d, J ~ 8.1 Hz, 2
H), 7.48 (br t, J ~ 7.5 Hz, 2 H), 7.77 (br s, 1 H), 7.81 (br s, 2 H),
7.84 (br d, J ~ 7.0 Hz, 2 H), 8.06 (s, 1 H), 8.12 (d, J ~ 7.7 Hz,
2 H); 13C NMR (125 MHz, CDCl3, 31 uC): d ~ 14.0, 22.5, 24.9,
27.1, 28.1, 28.3, 28.9, 28.9, 29.1, 29.1, 34.0, 42.9, 68.6, 69.2,
69.4, 69.7, 69.8, 105.9, 106.6, 106.8, 107.2, 107.9, 108.5, 116.5,
118.6, 120.2, 122.7, 122.9, 123.0, 123.1, 123.4, 124.5, 125.5,
To a solution of carbazole (1.0 g, 6.0 mmol), in DMF–THF
(1 : 2, 25 mL), was added sodium hydride (0.28 g, 12 mmol,
60% in oil) at room temperature. The mixture was stirred for
15 minutes before addition of 1,6-dibromohexane (7.3 g,
30 mmol) and stirred for 10 hours. The reaction was quenched
with MeOH (25 mL) and the mixture evaporated to dryness.
The residue was partitioned between CH2Cl2 (50 mL) and 3 M
HCl aq (50 mL). The organic layer was separated and washed
with H2O (60 mL), dried with anhydrous Na2SO4, filtered and
2798
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the filtrate was evaporated to dryness under reduced pressure,
and the residue was subjected to silica gel column chromato-
graphy (eluent: hexane–CH2Cl2, 1 : 1) to afford 12a (0.510 g,
26%) as a white microcrystalline powder and 12a.dimer as a
white solid: 12a: 1H NMR (300 MHz, CDCl3, 21 uC):
gave the crude product which was purified by silica gel column
chromatography (eluent: hexane–EtOAc) to yield the acid 14a
as a white solid: 1H NMR (500 MHz, CDCl3, 31 uC): d ~ 2.23
(ABq, J ~ 14.0 Hz, 2 H), 2.43 (t, J ~ 7.15 Hz, 2 H), 4.40 (t,
J ~ 7.0 Hz, 2 H), 7.26 (br t, J ~ 7.1 Hz, 2 H), 7.43 (d,
J ~ 8.1 Hz, 2 H), 7.49 (ddd, J ~ 8.0, 0.8, 0.9 Hz, 2 H), 8.12 (d,
J ~ 7.7 Hz, 2 H), 13.5–9.5 (br envelope, 1 H); 13C NMR
(125 MHz, CDCl3, 31 uC): d ~ 23.7, 31.0, 41.8, 108.4, 119.0,
120.0, 122.9, 125.7, 140.3, 179.1; MS (EIMS): m/z 253 [M]z;
elemental analysis calcd (%) for C16H15NO2: C 75.88, H 5.92,
N 5.53; found C 76.23, H 5.97, N 5.53.
d ~ 1.47–1.38 (m,
4 H), 1.92–1.78 (m, 4 H), 3.36 (t,
J ~ 15.0 Hz, 2 H), 4.32 (t, J ~ 15.0 Hz, 2 H), 7.25–7.20 (m,
2 H), 7.49–7.38 (m, 4 H), 8.10 (d, J ~ 9.0 Hz, 2 H); 13C NMR
(125 MHz, CDCl3, 31 uC): d ~ 26.5, 27.9, 28.8, 32.6, 42.8,
108.6, 118.0, 118.8, 120.4, 122.8, 125.6, 140.4; MS (LSIMS); m/z
331 [M z H]z; elemental analysis calcd (%) for C18H20NBr:
C 65.45, H 6.06, N 4.24; found C 65.49, H 6.12, N 4.13.
1
Compound 14b. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.44 (m, 2 H), 1.68 (q, J ~ 7.4 Hz, 2 H), 1.90 (q,
12a.dimer: H NMR (500 MHz, CDCl3, 31 uC): d ~ 1.80–1.95
(m, 6 H), 4.20–4.30 (m, 6 H), 7.28–7.30 (m, 8 H), 7.45–7.55 (m, 4
H), 8.12–8.20 (m, 4 H); 13C NMR (125 MHz, CDCl3, 31 uC):
d ~ 26.8, 42.6, 108.5, 118.9, 120.45, 122.8, 125.7, 140.2; MS
(LSIMS): m/z 417 [M z H]z.
The same procedure for 12a was followed for the synthesis of
12b, 13a, 13b and 13c. (Quantities used for these N-alkylation
reactions are shown in Table 3 of the supplementary mate-
rial.{)
J ~ 7.3 Hz,
2 H), 2.32 (t, J ~ 7.4 Hz, 2 H), 4.30 (t,
J ~ 7.1 Hz, 2 H), 7.24 (ddd, J ~ 7.8, 1.1, 1.1 Hz, 2 H), 7.39
(d, J ~ 8.1 Hz, 2 H), 7.47 (ddd, J ~ 8.1, 1.1, 1.1 Hz, 2 H), 8.1
(d, J ~ 7.7 Hz, 2 H); 13C NMR (125 MHz, CDCl3, 31 uC):
d ~ 24.3, 26.6, 28.6, 33.7, 42.7, 108.5, 118.8, 120.3, 122.8,
125.6, 140.3, 179.5; MS (EIMS): m/z 281 [M]z; elemental
analysis calcd (%) for C18H19NO2: C 76.88, H 6.76, N 4.98;
found C 76.84, H 6.60, N 4.97.
Compound 12b. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.40–1.24 (m, 8 H), 1.82–1.76 (m, 2 H), 1.89–1.83 (m, 2
H), 3.35 (t, J ~ 6.8 Hz, 2 H), 4.28 (t, J ~ 7.2 Hz, 2 H), 7.23
(ddd, J ~ 7.8, 0.8, 0.8 Hz, 2 H), 7.39 (d, J ~ 8.1 Hz, 2 H), 7.47
Compound 14c. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.38–1.27 (m, 6 H), 1.60–1.54 (m, 2 H), 1.88–1.82 (m, 2
H), 2.28 (t, J ~ 7.4 Hz, 2 H), 4.27 (t, J ~ 7.2 Hz, 2 H), 7.23
(ddd, J ~ 8.5, 0.9, 0.9 Hz, 2 H), 7.38 (d, J ~ 8.1 Hz, 2 H), 7.45
(ddd, J ~ 7.2, 1.0, 1.0 Hz, 2 H), 8.10 (d, J ~ 7.4 Hz, 2 H); 13
C
(ddd, J ~ 7.1, 1.1, 1.1 Hz, 2 H), 8.08 (d, J ~ 7.6 Hz, 2 H); 13
C
NMR (125 MHz, CDCl3, 31 uC): d ~ 27.1, 27.9, 28.5, 28.8,
29.1, 32.6, 33.8, 42.9, 108.6, 118.7, 120.3, 122.8, 125.5, 140.4;
MS (EIMS): m/z 357 [M]z.
NMR (125 MHz, CDCl3, 31 uC): d ~ 24.5, 27.1, 28.8, 29.0,
33.7, 43.0, 108.6, 118.7, 120.3, 122.8, 125.5, 140.4, 179.0; MS
(EIMS): m/z 309 [M]z; elemental analysis calcd (%) for
C20H23NO2: C 77.66, H 7.44, N 4.53; found C 77.59, H 7.53, N
4.46.
Compound 13a. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 2.22 (q, J ~ 6.9 Hz, 2 H), 2.35 (t, J ~ 7.2 Hz, 2 H),
3.67 (s, 3 H), 4.39 (t, J ~ 7.0 Hz, 2 H), 7.2 (ddd, J ~ 7.8, 0.9,
1.0 Hz, 2 H), 7.43 (d, J ~ 8.1 Hz, 2 H), 7.49 (ddd, J ~ 7.1, 1.1,
1.1 Hz, 2 H), 8.12 (d, J ~ 7.7 Hz, 2 H); 13C NMR (125 MHz,
CDCl3, 31 uC): d ~ 23.9, 30.8, 41.8, 51.5, 108.5, 118.9, 120.3,
122.8, 125.6, 140.3, 173.2; MS (EIMS): m/z 267 [M]z.
Acknowledgements
This research has been supported by the (i) EPSRC (MB), (ii)
Leverhulme Trust (MM), (iii) Perkin-Elmer/HEFCE in the UK
through the Joint Research Equipment Initiative (JREI).
Compound 13b. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.45–1.39 (m, 2 H), 1.67 (q, J ~ 7.4 Hz, 2 H), 1.90 (q,
J ~ 7.3 Hz, 2 H), 2.28 (t, J ~ 7.4 Hz, 2 H), 3.64 (s, 3 H), 4.30
(t, J ~ 7.1 Hz, 2 H), 7.26 (ddd, J ~ 7.7, 0.9, 1.0 Hz, 2 H), 7.40
(d, J ~ 8.1 Hz, 2 H), 7.49 (ddd, J ~ 8.1, 1.1, 1.1 Hz, 2 H), 8.12
(d, J ~ 7.7 Hz, 2 H); 13C NMR (125 MHz, CDCl3, 31 uC):
d ~ 24.6, 26.7, 28.5, 29.6, 33.7, 34.0, 42.7, 51.3, 108.5,
118.7, 120.3, 122.8, 125.5, 140.3, 173.8; MS (EIMS): m/z 295
[M]z.
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2
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The space charge field induced photorefractive effect was first
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Compound 13c. 1H NMR (500 MHz, CDCl3, 31 uC):
d ~ 1.34 (m, 6 H), 1.61 (q, J ~ 6.7 Hz, 2 H), 1.87 (q,
J ~ 7.1 Hz, 2 H), 2.28 (t, J ~ 7.4 Hz, 2 H), 3.67 (s, 3 H),
4.29 (t, J ~ 7.2 Hz, 2 H) , 7.24 (ddd, J ~ 7.8, 0.8, 0.7 Hz, 2 H),
7.40 (d, J ~ 8.1 Hz, 2 H), 7.47 (ddd, J ~ 8.1, 1.0, 1.0 Hz, 2 H),
8.12 (d, J ~ 7.74 Hz, 2 H); 13C NMR (125 MHz, CDCl3,
31 uC): d ~ 24.7, 27.0, 28.8, 28.9, 29.0, 33.9, 42.9, 51.3, 108.5,
118.6, 120.2, 122.8, 125.5, 140.3, 174.0; MS (ES): m/z 346
[M z Na]z.
4
5
6
Compound 14a
7
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(100 mL) was heated under reflux and a solution of sodium
hydroxide (0.112 g, 2.80 mmol) in H2O (10 mL) was added
under stirring and heating continued for 6 hours. After cooling,
the reaction mixture was poured onto crushed ice. The
precipitate which formed on acidification with dilute aqueous
HCl was then extracted with Et2O (3 6 50 mL). The combined
organic layers were washed with H2O (5 mL) and brine (5 mL),
and dried (MgSO4). Filtration and evaporation of the filtrate
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12 The carbazole moiety has been introduced into a low molecular
J. Mater. Chem., 2001, 11, 2790–2800
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15 We have chosen the triphenylene mesogenic structure for several
reasons: (i) they have pronounced photoconductivity (J. Simmerr,
B. Glu¨sen, W. Paulus, A. Kettner, P. Schumacher, D. Adam,
K. H. Etzbach, K. Siemeseyer, J. H. Wendorf, H. Ringsdorf and
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and it is well recognised that the supramolecular structure of disc-
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charge migration (see D. Markovitski, S. Marguet, L. K. Gallos,
H. Sigal, P. Millie, P. Argyrakis, H. Ringsdorf and S. Kumar,
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Balagurusamy, S. Krishna Prasad, S. Chandrasekhar, S. Kumar,
M. Manickam and C. V. Yelamaggad, Pramana, 1999, 53, 3) as
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Liq. Cryst., 1995, 18, 387), optoelectrical switching behaviour
(C. Y. Lin, H. L. Pan, M. A. Fox and A. J. Bard, Science, 1993,
261, 897), and photovoltaic behaviour (B. A. Greg, M. A. Foc and
A. J. Bard, J. Phys. Chem., 1990, 94, 1586), and (iii) doping with
TNF can induce liquid crystalline behaviour in many triphenylene
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