Dibenzo[a,c]phenazine with six-long alkoxy chains to probe optimization of mesogenic behavior

Article abstract of DOI:10.1039/b617827h

New hexaalkoxydibenzo[a,c]phenazines (HDBPs) with six-carbon long chains have been prepared, and their mesogenic behavior investigated. The incorporation of six peripheral alkoxy groups onto the larger, dipolar core bearing nitrogen atoms showed interesti

Full text of DOI:10.1039/b617827h

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PAPER
www.rsc.org/materials | Journal of Materials Chemistry
Dibenzo[a,c]phenazine with six-long alkoxy chains to probe optimization of
mesogenic behavior
Chi Wi Ong,*a Ja-Yi Hwang,a Mei-Chun Tzeng,a Su-Chih Liao,a Hsiu-Fu Hsub and Tsu-Hsin Changa
Received 6th December 2006, Accepted 23rd January 2007
First published as an Advance Article on the web 13th February 2007
DOI: 10.1039/b617827h
New hexaalkoxydibenzo[a,c]phenazines (HDBPs) with six-carbon long chains have been
prepared, and their mesogenic behavior investigated. The incorporation of six peripheral alkoxy
groups onto the larger, dipolar core bearing nitrogen atoms showed interesting thermal
properties. The crystal-to-mesophase transitions for the HDBPs (K–col) are similar to the
triphenylenes, but the clearing temperatures (Col–I) are shifted upwards by approx. 60 uC. HDBP
therefore possesses stable hexagonal mesophases in a fairly broad temperature range and form
homeotropically aligned films.
HDBPs differs from the well-known triphenylenes in that they
Introduction
have; (i) a larger core, (ii) an unsymmetrical core, (iii) a dipole
The liquid crystal (LC) properties of disc-shaped molecules
moment within the core. Furthermore, it will be interesting to
have been of considerable interest ever since their discovery by
Chandrasekhar1 in 1977. The number of known discotic LCs is
asymmetric dibenzophenazine possessing two methoxy groups
compare the symmetrically substituted HDBP with the
growing continuously;2 and their columnar arrangement is
and four hexyloxy groups, which is not mesogenic. Clearly, the
especially promising for the anisotropic transport of charge
unsymmetrical phenazine core and the symmetrical peripheral
carriers along the columns. Discotic LCs are being recognized
long alkyl chain may be expected to affect the packing of
for their potential applications in photovoltaic devices, field
molecules within the mesophase. In this regard, we may expect
effect transistors (FETs), light emitting diodes (LEDs) and
the unsymmetrical core to increase intermolecular lateral
other molecular electronics.3 Some of the most prominent
slippage; while the dipole–dipole interaction contributes to
discotic LCs range from the widely-investigated triphenylenes,4
the preferential antiparallel orientation of the adjacent
to porphyrins,5 phthalocyanines,5 hexaazatriphenylenes,6–8
molecules within the column to enhance intracolumnar p–p
perylenes,9 dibenzopyrenes,10 hexabenzocoronenes,11,12 diben-
interactions. This work might lead to the discovery of new
zoquinoxalines13 and dibenzo[a,c]phenazine.14
hexaalkoxydibenzo[a,c]phenazines (HDBP), discotic liquid
The dibenzo[a,c]phenazine core possesses a phenanthrene
crystals with a useful mesogenic range, thereby improving
ring fused to pyrazine, and this gives rise to a molecular dipole
their processing characteristics for applications.
moment. The dipole moment contributes to the preferential
antiparallel orientation of adjacent molecules within the
Results and discussion
column. Recently, Williams et al.14 reported low-symmetry
tetraalkoxydibenzo[a,c]phenazines with electron withdrawing
groups at the pyrazine moiety exhibit liquid crystalline
properties by forming fairly symmetrical columns through
this kind of interaction.14 However, electron-donating methyl
and methoxy groups at the pyrazine moiety of tetraalkoxy-
dibenzo[a,c]phenazines are nonmesogenic.14
Hexaalkoxydibenzo[a,c]phenazine (HDBP) derivatives have
been synthesised directly from the condensation of 1,2-
diamines with benzils followed by oxidative cyclization
(route A); or from the condensation of 1,2-diamines with
phenanthrene-9,10-diones (route B).13,14 While preparation of
liquid crystalline materials is often (but not always) simple,
their purification is usually difficult and tedious. As such, both
routes were examined.
This report prompted us to disclose results of our own work
in this area, which utilises the more symmetrical hexaalkoxy-
dibenzo[a,c]phenazines with long carbon chains, shown by the
general formula HDBP, to obtain mesogenic properties. These
new HDBP with six-carbon long alkoxy chains can provide
further insight into the relative importance of the peripheral
side-chains in enforcing the propensity of these compounds to
self assemble into columnar liquid crystal phases. The new
Our initial approach to synthesise hexaalkoxydibenzo-[a,c]
phenazines (HDBP) is outlined in (Scheme 1, route A). The
tetraalkoxybenzils 1a–e were synthesised from the reaction of
1,2-bisalkoxybenzene (from the alkylation of catechol in .90%
yield) and oxalyl chloride in 60–65% yield in accordance to the
procedure described by Wegner.15 The above protocol to
synthesise symmetrical tetraalkoxybenzils is greatly superior;
Williams14,16 has previously used a benzoin condensation
route reported by Wenz16 which gave an average overall yield
of 29% in four steps. The tetraalkoxybenzils 1a–e were then
aDepartment of Chemistry, National Sun Yat Sen University, Kaohsiung
80424, Taiwan E-mail: cong@mail.nsysu.edu.tw; Fax: +886 7 5253908;
Tel: +886 7 5252000-3923
bDepartment of Chemistry, Tamkang University, Tamsui 25137, Taiwan
E-mail: hhsu@mail.tku.edu.tw; Fax: +886 2 26209924;
Tel: +886 2 26215656
condensed with 1,2-bisalkoxy-4,5-diaminobenzenes
2 pre-
viously prepared in our laboratory7 to furnish the quinoxaline
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Condensation of the tetraalkoxyphenanthrene-9,10-diones
with 1,2-bisalkoxy-4,5-diaminobenzenes furnished hexaalkoxy-
dibenzo[a,c]-phenazines (HDBP-1–5) in yields ranging from
35–40%, and the problem of purification was rectified. In all
cases, the main product were obtained readily. Thus, route B
allowed us to synthesise the key compound in a much higher
overall yield (32–38%) from benzils.
The phase-forming properties of 2,3-bis(3,4-dialkoxyphe-
nyl)-6,7-dialkoxyquinoxaline 3 and hexaalkoxydibenzo[a,c]
phenazine (HDBP) derivatives were investigated using polar-
ized optical microscopy (POM), differential scanning calori-
metry (DSC) and variable temperature X-ray diffraction
(XRD) and the results summarized in (Fig. 1), (Table 1) and
(Table 2). The 2,3-bis(3,4-dioctyloxyphenyl)-6,7-dioctyloxy-
quinoxaline, 3c, was found to be non-mesogenic, melting
directly from the crystalline solid to isotropic liquid. The
present of six octyloxy peripheral chains cannot overcome the
non-planarity of the unfused aromatic rings in 2,3-bis(3,4-
dialkoxyphenyl)-6,7-dialkoxyquinoxaline, thus suppressed
mesophase formation. Even with the use of a dodecyloxy side
chain, 3e, this did not lead to the formation of a mesophase.
Mesogenic behavior is observed for all the synthesised
hexaalkoxydibenzo[a,c]phenazine derivatives with long alkoxy
chains (HDBP-1: R = C4H9, HDBP-2: R = C6H13, HDBP-3:
R = C8H17, HDBP-4: R = C10H21, and HDBP-5: R = C12H25).
Thus, planarization of the discogen core has lead to favorable
mesophase formation. A typical birefringent fan texture of the
columnar mesophase was observed by POM (Fig. 1f, without
cover glass). All other liquid crystalline members of the series
also exhibit similar texture, confirming the columnar nature of
the mesophase. Most of the compounds also shows large
domains of homeotropically aligned region, where columns are
perpendicular to the glass plane, indicating the planar
molecules packed parallel to the substrate surface (Fig. 1a–e,
with cover glass). Geerts has recently illustrated that the
confinement imposed on the film between two glass plates
plays an important role for homeotropic alignment.19
Examination of these compounds by DSC revealed that
HDBP-1, HDBP-2 and HDBP-5 undergo two phase transi-
tions upon heating; which were identified by POM as crystal-
to-liquid crystal and liquid crystal-to-isotropic liquid
transitions (Fig. 2a: DSC of HDBP-1). The remaining
compounds, HDBP-3 and HDBP-4, each undergo three phase
transitions (Fig. 2b: DSC of HDBP-3). We were not able to
confirm the identity of the first liquid crystal phase having a
very narrow phase range, while the broader second liquid
crystal phase were easily identified by POM. X-ray diffraction
studies of HDBP-1, 2, 3, 4 and 5 confirmed the mesophase
assignment made by POM and DSC. The pattern shows a
strong maximum in the low angle region that corresponds
to the (100) reflection from the two dimensional hexagonal
Scheme 1 The synthesis of hexaalkoxydibenzo[a,c]phenazines
(HDBPs)
derivatives. A variety of oxidants such as palladium(II) acetate,
FeCl3, thallium(III) oxide and vanadium(V) oxyfluoride have
been studied for the conversion of 3,39,4,49-tetraalkoxy-
substituted to the dibenzoquinoxaline. The best results were
achieved, however, with VOF3, which cleanly oxidises benzils
to phenanthrene-9,10-diones. Thus, we choose to use VOF3
for the oxidative cyclization, and this furnishes hexaalkoxy-
dibenzo[a,c]phenazines (HDBPs) in excellent yield. The
product obtained has to be rigorously purified due to its close
resemblance to the quinoxalines starting material. Although
we were able to obtain pure HDBPs by column chromato-
graphy, however, repeating separation was required due to
poor resolution, and much remained as a mixture. In spite of
requiring tedious separation, this route has the advantage of
enabling us to study the mesogenic properties for both the
uncyclized 2,3-bis(3,4-dialkoxyphenyl)-6,7-dialkoxyquinoxa-
line 3 and cyclised hexaalkoxydibenzo[a,c]phenazine (HDBP)
derivatives.
˚
lattice with a lattice constant a in A. Other two small peaks can
Given the low overall level of yield for the synthesis of
HDBPs from route A (14–18% from benzils), we chose to
focus upon an alternative synthetic route that utilised
tetraalkoxyphenanthrene-9,10-diones 4a–e15,17,18 as starting
materials. Tetraalkoxyphenanthrene-9,10-diones were synthe-
be indexed to the (110) and (200) reflections, confirming the
Colh assignment (Fig. 3: XRD pattern of HDBP-3). At
the wide-angle region, two diffuse scattering maxima were
observed, corresponding to a distance of approximately
˚
4.6 and 3.5 A, typical of the interchain halo and intracolumnar
sized from the oxidative cyclization of the tetraalkoxybenzils
15
p–p stacking distances, respectively. We have demonstrated
1a–e with VOF3
cleanly in excellent yield (90–95%).
that by introducing six alkoxy peripheral chains at the
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Fig. 1 The texture of (a) HDBP-1 at 200 uC, 6100, (b) HDBP-2 at 150 uC, 6100, (c) HDBP-3 at 150 uC, 6100, (d) HDBP-4 at 110 uC, 6100, (e)
HDBP-5 at 118 uC, 6100, with cover glass (homeotropic), (f) HDBP-5 at 118 uC, 6100, without cover glass.
dibenzo[a,c]phenazine core can enforced the formation of
liquid crystalline phases.
those of the corresponding triphenylenes.1,20,21 The introduc-
tion of a larger core and a dipole moment within the core of
HDBP-1–5 does not affect the observed crystal to mesophase
transition (K–Col). Furthermore, the intermolecular spacing
of HDBPs with six peripheral alkoxy chains correlate well
to those of the triphenylenes. Investigation by XRD also
revealed that the intercolumnar spacing for HDBPs
calculated from the d-spacing of the (100) reflection increases
with increasing alkoxy chain length. Thus increasing the
We would like to stress here that the crystal to mesophase
transition temperature (TK–Col) for HDBP-1–5 (Table 1)
is much lower, as compared to the reported tetraalkoxy-
dibenzo[a,c]phenazines with electron withdrawing groups.14
The unsymmetical core can led to a less-efficient packing
of the solid, and thus lowering the melting point. It is
interesting to note that these melting points are similar to
Table 1 The phase behaviors of HDBP-1, 2, 3, 4 and 5. The transition temperatures (uC) and enthalpies (in parentheses/kJ mol21) were
determined by DSC at 10 uC min21
Compound
Chain
Phase transitiona
3c
R = C8H17
3e
R = C12H25
R = C4H9
R = C6H13
R = C8H17
HDBP-1
HCBP-2
HCBP-3
HCBP-4
R = C10H21
R = C12H25
HCBP-5
a
K, crystalline phase; Colx, indistinct phase; Colh, hexagonal columnar; I, isotropic.
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Table 2 Variable-temperature XRD data for compounds HDBP-1–5
˚
d-spacing/A
˚
Lattice constants/A
Compound
Chain
Temperature/uC
Miller indices (hkl)
HDBP-1
R = C4H9
190
16.95
9.72
8.44
6.39
4.60
(100)
(110)
(200)
(210)
Alkyl halo
Core–core
(100)
a = 19.57
3.53
HDBP-2
HDBP-3
R = C6H13
R = C8H17
80
80
18.02
1.65
4.43
a = 20.81
a = 24.23
(110)
Alkyl halo
Core–core
(100)
(110)
(200)
(210)
3.47
20.98
12.14
10.46
7.95
4.56
3.47
22.89
13.11
11.43
4.55
Alkyl halo
Core–core
(100)
(110)
(200)
Alkyl halo
Core–core
(100)
(110)
(200)
HDBP-4
HDBP-5
R = C10H21
90
a = 26.43
a = 28.71
3.47
R = C12H25
100
24.86
14.44
12.54
4.78
Alkyl halo
Core–core
3.55
alkoxy chain length leads to a lowering of the melting
temperature.
temperature. The lateral dipole of the mesogenic core can
stabilises the columnar structure through an antiparallel
packing of adjacent discs within the column, thus correlating
to an anti-ferroelectric ordering of the lateral dipole along the
column. Indeed, it has been reported that introducing a dipole
through a peripheral substitution in triphenylenes caused an
increase in the clearing temperature.22 This is also seen in
tetraalkoxydibenzo[a,c]phenazines having electron withdraw-
ing group at the pyrazine moiety to induce strong dipole, thus
exhibit a high clearing temperature.14 It is apparent that the
dipole–dipole interaction of adjacent molecules within the
column can lead to an increase in the intracolumnar p–p
interaction, and therefore stabilises the mesophase. The
While HDBPs have a lower clearing temperature compared
to tetraalkoxydibenzo[a,c]phenazines with electron withdraw-
ing groups,14 it is perhaps notable that they are shifted
upwards by approx. 60 uC with respect to the triphenylene
counterpart.1,20,21 This observation provides quantitative
evidence that the non-cooperation of a larger core and a
dipole moment within the core leads to a higher clearing
intracolumnar stacking distance for all the HDBPs is approx.
23
˚
˚
3.5 A, smaller than the van der Waals sum of 3.54 A, and is
in consistent with a good p-stacking tendency.
Much effort has been carried out for broadening the
mesogenic range of single component discotic liquid crys-
tals.24–28 The fact that HDBP-1, 2, 3, 4 and 5 exhibit a low
melting and a relatively high clearing temperature provide the
Fig. 2 DSC curves of (a) HDBP-1 and (b) HDBP-3. The transition
temperatures (uC) were determined by DSC at 10 uC min21
Fig. 3 Powder X-ray diffraction pattern of HDBP-3 at 80 uC.
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10 uC min21. Polarized optical microscopy (POM) was carried
out on a OLYMPUS CX41 with a Mettler FP90/FP82HT hot
stage system. X-Ray powder diffraction data were collected on
the wiggler beamline BL17A of the National Synchrotron
Radiation Research Center (NSRRC), Taiwan, using
a
triangular bent Si(111) monochromator and a wavelength of
˚
1.334431 A. The sample in a 1 mm capillary was mounted on
the Huber 5020 diffractometer. An air stream heater is
equipped at BL17A beamline and the temperature controller
is programmable by a PC with a PID feedback system.
Synthesis
General procedure for the preparation of 3c, 3e and
hexaalkoxydibenzo[a,c]phenazines (HDBPs): to a solution of
tetraalkoxybenzil 1 (0.01 mol) or tetraalkyloxyphenanthrene-
9,10-dione 4 (0.01 mol) and 1,2-bisalkoxy-4,5-diamino-ben-
zene (0.01 mol) in dichloromethane (35 mL) was added acetic
acid (3.0 mL). The reaction mixture was stirred under nitrogen
for 1 day. Removal of the solvent give crude product that has
to be purified.
Fig. 4 Graphical representation of the phase ranges for 3c, 3e and
HDBP-1–5.
basis for their relatively wide mesophase range of between 55–
90 uC (Fig. 4), whereas the mesogenic range for triphenylenes
with similar peripheral alkoxy chains is in the range of
10–30 uC.1,21 Whereas the synthesis of a triphenylene core
with lateral dipole to improved mesophase range is tedious,
our HDBPs with a build-in dipole can be readily synthesized.
The crude products were purified by column chromatogra-
phy on silica gel using dichloromethane as eluent and this give
some pure 3, together with fractions containing mixtures of
compounds. The mixtures were again column chromato-
graphed several times. Compound 3, obtained from chroma-
tography, was re-crystallized from ethyl acetate or co-solvent
(methanol–dichloromethane) at least five times to give pure 3
as a white solid.
Conclusions
In conclusion, hexaalkoxydibenzo[a,c]phenazines, HDBP-1, 2,
3, 4 and 5, with long carbon chains have been shown to exhibit
liquid crystalline behavior. We have highlighted the issue of
incorporating dual effects arising as a result of using unsym-
metrical–core, dipole–core and peripheral side chains to
improve the mesogenic behavior of these discotic liquid
crystals. These could lead to the synthesis of favorable discotic
compounds which are more suitable for applications in elec-
tronic devices due to their lower crystal-to-mesophase transi-
tion temperature and broader mesophase temperature range.
We are continuing to pursue the design of new hexaalkoxy-
dibenzo[a,c]phenazines to optimize the LC properties.
The crude products from the preparation of HDBPs was
column chromatography once on silica gel with dichloro-
methane as eluent to give yellowish solid. Pure HDBPs can be
readily obtained by re-crystallization from ethyl acetate or
hexane. Preparative TLC (EtOAc–hexane (1 : 5) can also be
used to obtain pure HDBPs.
The yield of 3c is 35%, 3e is 40% after purification. The yield
of HDBP-1 is 38%, HDBP-2 is 35%, HDBP-3 is 33%, HDBP-4
is 34%, and HDBP-5 is 32% from route B after purification to
give a very pure sample.
1
3c: H NMR (CDCl3, 500 MHz): d 7.41 (s, 2H), 7.07 (dd,
Experimental
2H, J = 9.2 and 1.0 Hz), 7.01 (d, 2H, J = 1.0 Hz), 6.83 (d, 2H,
J = 8.5 Hz), 4.18 (t, 4H, J = 6.5 Hz), 3.99 (t, 4H, J = 6.5 Hz),
3.81 (t, 4H, J = 6.5 Hz), 1.93 (quint, 4H, J = 7.0 Hz), 1.82
(quint, 4H, J = 7.0 Hz), 1.71 (quint, 4H, J = 7.0 Hz), 1.57–1.21
(m, 60H), 0.94–0.84 (m, 18H); 13C NMR (CDCl3, 125 MHz): d
152.54, 150.26, 149.35, 148.61, 137.83, 132.04, 122.56, 115.28,
113.24, 107.06, 69.15, 69.12, 69.05, 34.61, 31.81, 31.80, 31.77,
31.54, 29.38, 29.34, 29.29, 29.25, 29.22, 29.21, 29.11, 28.79,
26.11, 25.99, 25.22, 22.65, 22.62, 22.60, 14.04; LRMS (FAB):
1052 (M+ + 1, 29.07); anal. calcd for C68H110N2O6: C, 77.37;
H, 10.54; N, 2.66. Found: C, 77.67; H, 10.48; N, 2.52%.
General
All reactions were conducted under an atmosphere of nitrogen
in oven-dried glassware. Dichloromethane was distilled over
calcium hydride. 1,2-bisalkoxy-4,5-diaminobenzene7 and tetra-
alkyloxyphenanthrene-9,10-dione15–17 were prepared accord-
ing to the published procedures. Nuclear magnetic resonance
spectra were recorded on a Varian Gemini-200 MHz and
Varian Unity-INOVA-500 MHz spectrometer. (CDCl3).
Chemical shifts are reported in ppm relative to residual
CHCl3 (d = 7.26, H; 77.0, 13C). Mass spectra were obtained
1
1
3e: H NMR (CDCl3, 500 MHz): d 7.38 (s, 2H), 7.07 (dd,
on JEOL JMS-HX110 or ESI on Bruker APE (I) FT-MS and
elemental analyses were carried out on a Heraeus CHN-O
Rapid Elementary Analyzer.
2H, J = 8.5 and 2.0 Hz), 7.00 (d, 2H, J = 2.0 Hz), 6.82 (d, 2H,
J = 8.5 Hz), 4.18 (t, 4H, J = 6.5 Hz), 3.99 (t, 4H, J = 6.5 Hz),
3.81 (t, 4H, J = 6.5 Hz), 1.93 (quint, 4H, J = 7.0 Hz), 1.82
(quint, 4H, J = 7.0 Hz), 1.71 (quint, 4H, J = 7.0 Hz), 1.56–1.21
(m, 108H), 0.93–0.85 (m, 18H); 13C NMR (CDCl3, 125 MHz):
d 152.43, 150.44, 149.29, 148.63, 137.98, 132.36, 122.53,
115.29, 113.30, 107.25, 69.20, 69.12, 69.07, 31.92, 31.84,
Instrumental
Differential scanning calorimetry (DSC) was measured on a
Perkin-Elmer Pyris1 with heating and cooling rates of 5 and
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31.82, 31.77, 31.54, 29.68, 29.65, 29.61, 29.40, 29.38, 29.36,
29.32, 29.28, 29.24, 29.14, 28.83, 26.01, 22.68, 22.65, 22.62,
22.60, 14.11, 14.09; LRMS (FAB): 1388 (M+, 18.11); anal.
calcd for C92H158N2O6: C, 79.60; H, 11.47; N, 2.02. Found: C,
79.67; H, 11.40; N, 2.05%.
HDBP-1: 1H NMR (CDCl3, 500 MHz): d 8.76 (s, 2H), 7.76
(s, 2H), 7.56 (s, 2H), 4.36 (t, J = 6 Hz, 8H), 4.28 (t, J = 6.5 Hz,
4H), 2.01–1.93 (m, 12H), 1.64–1.58 (m, 12H), 1.08–1.05 (m,
18H); 13C NMR (CDCl3, 125 MHz): d 152.85, 151.06, 149.38,
139.31, 138.95, 125.71, 123.99, 108.03, 106.63, 106.44, 69.32,
68.87, 68.81, 31.39, 30.97, 19.39, 19.33, 13.98, 13.91; MALDI-
TOF: 731; HRMS (ESI) m/z 713.4525 (713.4529 calculated for
C44H61N2O6 [M + H+]).
HDBP-2: 1H NMR (CDCl3, 500 MHz): d 8.79 (s, 2H), 7.76
(s, 2H), 7.60 (s, 2H), 4.36 (t, J = 6.5 Hz, 4H), 4.30–4.26 (m,
8H), 2.02–1.94 (m, 12H), 1.64–1.36 (m, 36H), 0.96–0.93 (m,
18H); 13C NMR (CDCl3, 125 MHz): d 152.99, 151.17, 149.42,
125.79, 108.05, 106.43, 69.64, 69.21, 69.15, 31.66, 31.57, 29.34,
29.28, 28.89, 25.84, 25.81, 25.76, 22.65, 22.61, 14.07, 14.04,
140.02; MALDI-TOF: 880; HRMS (ESI) m/z 881.6410
(881.6407 calculated for C56H85N2O6 [M + H+]).
HDBP-3: 1H NMR (CDCl3, 500 MHz): d 8.76 (s, 2H), 7.77
(s, 2H), 7.53 (s, 2H), 4.35 (t, 4H, J = 6.5Hz), 4.27 (t, 8H, J =
6.5 Hz), 2.04–1.92 (m, 12H), 1.64–1.54 (m, 12H), 1.48–1.28 (m,
48H), 0.92–0.88 (m, 18H); 13C NMR (CDCl3, 125 MHz): d
152.75, 150.99, 149.35, 139.45, 139.11, 125.68, 124.18, 107.99,
106.74, 106.50, 69.66, 69.12, 69.07, 31.853, 31.846, 31.83,
29.48, 29.46, 29.41, 29.37, 29.35, 29.33, 29.28, 28.95, 26.18,
26.16, 26.09, 22.69, 14.11; LRMS (FAB): 1049 (M+, 19.98);
anal. calcd for C68H108N2O6: C, 77.81; H, 10.37; N, 2.67.
Found: C, 77.68; H, 10.38; N, 2.65%.
HDBP-4: 1H NMR (CDCl3, 500 MHz): d 8.76 (s, 2H), 7.76
(s, 2H), 7.54 (s, 2H), 4.35 (t, J = 6.5 Hz, 8H), 4.27 (t, J = 6.5 Hz,
4H), 2.02–1.94 (m, 12H), 1.62–1.28 (m, 84H), 0.91–0.87 (m,
18H); 13C NMR (CDCl3, 125 MHz): d 152.78, 151.00, 149.35,
139.40, 139.06, 125.69, 124.13, 108.01, 106.71, 106.51, 69.67,
69.13, 69.08, 31.93, 29.68, 29.63, 29.62, 29.59, 29.54, 29.50,
29.42, 29.38, 29.36, 28.95, 26.18, 26.16, 26.09, 22.69, 14.11;
MALDI-TOF: 1217; HRMS (ESI) m/z 1218.0079 (1218.0085
calculated for C80H133N2O6 [M+H+]).
HDBP-5: 1H NMR (CDCl3, 500 MHz): d 8.76 (s, 2H), 7.76
(s, 2H), 7.53 (s, 2H), 4.35 (t, 4H, J = 6.5 Hz), 4.27 (t, 8H, J =
6 Hz), 2.04–1.90 (m, 12H), 1.66–1.52 (m, 12H), 1.49–1.20 (m,
96H), 0.98–0.84 (m, 18H); 13C NMR (CDCl3, 125 MHz): d
152.74, 150.97, 149.34, 139.45, 139.12, 125.67, 124.20, 107.99,
106.75, 106.50, 69.67, 69.11, 69.05, 31.93, 31.58, 29.74, 29.68,
29.63, 29.54, 29.51, 29.42, 29.38, 28.97, 28.90, 26.17, 26.11,
25.77, 22.69, 22.62, 14.11, 14.04; LRMS (FAB): 1385 (M+,
7.12); anal. calcd for C92H156N2O6: C, 79.71; H, 11.34; N, 2.02.
Found: C, 79.52; H, 11.43; N, 1.95%.
Acknowledgements
We gratefully acknowledge the National Sciences Council of
Taiwan (NSC) for funding and National Synchrotron
Radiation Research Center (NSRRC) for carrying out XRD
experiments.
References
1 S. Chandrasekhar, B. K. Sadashiva and K. A. Suresh, Pramana,
1977, 9, 471.
2 (a) R. J. Bushby and O. R. Lozman, Curr. Opin. Colloid Interface
Sci., 2002, 7, 343; (b) S. Kumar, Chem. Soc. Rev., 2006, 35, 83.
3 M. O’Neill and S. M. Kelly, Adv. Mater., 2003, 15, 1135.
4 N. Boden and B. Movaghar, in Handbook of Liquid Crystals,
vol. 2B, ed. D. Demus, J. Goodby, G. W. Gray, H.-W. Spiess and
V. Vill, Wiley-VCH, New York, 1998, pp. 781.
5 H. Eichorn, J. Porphyrins Phthalocyanines, 2000, 4, 88.
6 O. Roussel, G. Kestemont, J. Tant, V. de Halleux, R. G. Aspe,
J. Levin, A. Remacle, I. R. Gearba, D. Ivanov, M. Lehmann and
Y. Geerts, Mol. Cryst. Liq. Cryst., 2003, 396, 35.
7 C. W. Ong, S.-C. Liao, T.-H. Chang and H.-F. Hsu, Tetrahedron
Lett., 2003, 44, 1477.
8 T.-H. Chang, B.-R. Wu, M. Y. Chiang, S.-C. Liao, C. W. Ong,
H.-F. Hsu and S.-Y. Lin, Org. Lett., 2005, 7, 4075.
9 G. R. J. Mu¨ller, C. Meiners, V. Enkelmann, Y. H. Geerts and
K. Mu¨llen, J. Mater. Chem., 1998, 8, 61.
10 S. Kumar, J. J. Naidu and D. S. S. Rao, J. Mater. Chem., 2002, 12,
1335.
11 A. Fechtenko¨tter, K. Saalwa¨chter, M. A. Harbison, K. Mu¨llen and
H. W. Spiess, Angew. Chem., Int. Ed., 1999, 38, 3039.
12 C. Y. Liu, A. Fechtenko¨tter, M. D. Watson, K. Mu¨llen and
A. Bard, J. Chem. Mater., 2003, 15, 124.
13 B. Mohr, G. Wegner and K. Ohta, J. Chem. Soc., Chem. Commun.,
1995, 995.
14 E. J. Foster, R. B. Jones, C. Lavigueur and V. E. Williams, J. Am.
Chem. Soc., 2006, 126, 8569.
15 B. Mohr, V. Enkelmann and G. Wegner, J. Org. Chem., 1994, 59,
635.
16 G. Wenz, Makromol. Chem., Rapid Commun., 1985, 6, 577.
17 E. J. Foster, J. Babuin, N. Nguyen and V. E. Williams, Chem.
Commun., 2004, 2052.
18 E. J. Foster, C. Lavigueur, Y.-C. Ke and V. E. Williams, J. Mater.
Chem., 2005, 15, 3989.
19 V. C. Cupere, J. Tant, P. Viville, R. Lazzaron, W. Osikowicz,
W. R. Salaneck and Y. H. Greets, Langmuir, 2006, 22, 7798.
20 E. O. Arikainen, N. Boden, R. J. Bushby, J. Clements,
B. Movaghar and A. Wood, J. Mater. Chem., 1995, 5, 2161.
21 S. J. Cross, J. W. Goodby, A. W. Hall, M. Hird, S. M. Kelly,
K. J. Toyne and C. Wu, Liq. Cryst., 1998, 25, 1.
22 R. J. Bushby, K. J. Donovan, T. Kreouzis and O. R. Lozman,
Opto-Electron. Rev., 2005, 13, 269.
23 A. Bondi, J. Phys. Chem., 1964, 68, 441.
24 D. Guillon, A. Skoulios, C. Piechocki, J. Simon and P. Weber,
Mol. Cryst. Liq. Cryst., 1983, 100, 275.
25 I. Tabushi, K. Yamamura and Y. Okada, J. Org. Chem., 1987, 52,
2502.
26 I. Tabushi, K. Yamamura and Y. Okada, Tetrahedron Lett., 1987,
28, 2269.
27 D. M. Collard and C. P. Lillya, J. Am. Chem. Soc., 1991, 113, 8577.
28 M. Werth, S. U. Vallerien and H. W. Spiess, Liq. Cryst., 1991, 10,
759.
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