A triphenylene-based small molecule compatibiliser using incompatible pendent chains

Article abstract of DOI:10.1039/c5ra23904d

To demonstrate that incompatible pendent chains can be used as a strategy to control the morphology of blends of immiscible materials, we have developed a novel triphenylene-based amphiphile-like mesogen with hydrophobic (alkyl) chains and hydrophilic (2-(2-methoxyethoxy)ethoxy) pendent chains, named TP6Gall hereafter. TP6Gall is a roomerature liquid crystal presenting a cubic phase with a clearing point of 30°C. Blends of TP6Gall in various amounts with an equimolar mixture of the hydrophobic 2,3,6,7,10,11-hexahexyloxytriphenylene (TP6) and hydrophilic 2,3,6,7,10,11-hexa(2-(2-methoxyethoxy)ethoxy)triphenylene (TP6EO2M) have been studied by polarised optical microscopy (POM), differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS). Without TP6Gall, the TP6TP6EO2M mixture exhibits large incompatible domains of pure TP6 and pure TP6EO2M. As the quantity of TP6Gall increases in the blend, the size of the domains decreases significantly. Ultimately, when the proportion of TP6Gall reaches 50 mol% of the blend, μm-featured interpenetrated networks of crystalline TP6EO2M and of TP6 mixed with TP6Gall are obtained. Interestingly, a single liquid phase is obtained above the clearing point of the blend. Furthermore, no macrophase separation is observed upon multiple temperature cycles between roomerature and the temperature above the clearing point of the blend and the interpenetrated network is reliably reformed upon cooling.

Full text of DOI:10.1039/c5ra23904d

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A triphenylene-based small molecule
compatibiliser using incompatible pendent chains†
Cite this: RSC Adv., 2016, 6, 10655
*
Antoine J. Herbaut and Etienne Baranoff
To demonstrate that incompatible pendent chains can be used as a strategy to control the morphology of
blends of immiscible materials, we have developed a novel triphenylene-based amphiphile-like mesogen
with hydrophobic (alkyl) chains and hydrophilic (2-(2-methoxyethoxy)ethoxy) pendent chains, named
TP6Gall hereafter. TP6Gall is a room-temperature liquid crystal presenting a cubic phase with a clearing
point of 30 ꢀC. Blends of TP6Gall in various amounts with an equimolar mixture of the hydrophobic
2,3,6,7,10,11-hexahexyloxytriphenylene (TP6) and hydrophilic 2,3,6,7,10,11-hexa(2-(2-methoxyethoxy)
ethoxy)triphenylene (TP6EO2M) have been studied by polarised optical microscopy (POM), differential
scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS). Without TP6Gall, the
TP6 : TP6EO2M mixture exhibits large incompatible domains of pure TP6 and pure TP6EO2M. As the
quantity of TP6Gall increases in the blend, the size of the domains decreases significantly. Ultimately,
when the proportion of TP6Gall reaches 50 mol% of the blend, mm-featured interpenetrated networks of
crystalline TP6EO2M and of TP6 mixed with TP6Gall are obtained. Interestingly, a single liquid phase is
obtained above the clearing point of the blend. Furthermore, no macrophase separation is observed
upon multiple temperature cycles between room-temperature and the temperature above the clearing
point of the blend and the interpenetrated network is reliably reformed upon cooling.
Received 12th November 2015
Accepted 18th January 2016
DOI: 10.1039/c5ra23904d
www.rsc.org/advances
addition, as the role of the additive is purely structural, only a small
amount should be used, and as it oen remains in the blends, it
can impact further the long-term stability of electronic devices.10
1 Introduction
Mixing two compounds is an effective strategy to create new
materials combining the properties of the two components and
possibly displaying new and enhanced qualities. However when
two immiscible substances are mixed together, macrophase
separation into two thermodynamically different phases generally
occurs and leads to materials with inferior properties. In polymer
science, diblock copolymers have been successfully used as com-
patibilisers to suppress the macrophase separation of polymer
blends.1–6 This approach is very important for the whole plastics
industry,7 including plastic electronics such as polymer solar cells
in which compatibilisers help to control the morphology of donor/
acceptor blends and develop more stable devices.4,5
Small molecules have well-dened structures and can be
sublimed for purication and device preparation, which are
advantages over polymers. However, the morphology of blends of
functional small molecules is challenging to control; it relies
mainly on the use of non-functional additives and/or annealing
treatments.8,9 Furthermore, the morphology obtained with such
methods is only kinetically trapped and macrophase separation,
the thermodynamically stable morphology, will occur over time. In
To overcome the aforementioned limitations of structural
additives, functional small molecule compatibilisers are ex-
pected to be a viable strategy to control the morphology of
blends of small molecules in a simple manner, yet examples in
the literature are scarce. Kim et al. have developed thiophene–
C60 dyads as interfacial agents for compatibilising blends of
P3HT and PCBM for organic solar cell.11 They have shown that
macrophase separation and domain coarsening can be sup-
pressed, which result in increased efficiency and stability. A
similar approach was recently reported by Raja et al.12
In another domain of application, Date and Bruce have
prepared a rod-disk shape amphiphile to suppress the macro-
phase separation in a blend of rod and disklike mesogens.13
A
homogenous nematic phase was obtained over a large range of
amphiphile concentration demonstrating the compatibilisation
of the rod and disk-like mesogens. Kouwer and Mehl also
developed a series of mesogenic rod-disk shape amphiphiles.14
Mixing the amphiphile with the rod-like mesogen shows
a homogeneous isotropic phase over a wide range of tempera-
ture while mixing with the disklike mesogen shows one mon-
otropic nematic phase. No mixing studies were carried out on
the mixture of rods, disks, and amphiphiles. Other amphiphile-
like mesogens were described in the literature but no studies of
blends were carried out.15–19
School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
E-mail: e.baranoff@bham.ac.uk; Tel: +44 (0)1214142527
† Electronic supplementary information (ESI) available: Full synthetic details, 1H
and 13C NMR spectra, additional POM images, DSC curves, SAXS patterns. See
DOI: 10.1039/c5ra23904d
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pure as minor triphenylene-based impurities could not be fully
removed by chromatography columns.22 TP6Gall was obtained
in 12 steps with 5% overall yield using a convergent synthesis to
couple the hydrophilic and the hydrophobic fragments, Scheme
2. The hydrophobic triphenylene 16 was synthesized by the
biphenyl–phenyl coupling method.23 Briey, a FeCl3-based
Scholl type oxidative coupling between 3,30,4,40-tetrakis-
(hexyloxy)-1,10-biphenyl and 1-(hexyloxy)-2-isopropoxybenzene
afforded the monohydroxy-pentahexyloxytriphenylene 11,24
which was reacted with 1,6-dibromohexane. The hydrophilic
moiety 14 was derived from ethyl gallate substituted with 2-(2-
methoxyethoxy)ethanol chains, which ester function was
reduced to alcohol and then chlorinated. 1,3-Dihydroxybenzene
was used as a linker between the hydrophilic and the hydro-
phobic parts (synthetic details in ESI†).
Scheme 1 Chemical structure of the investigated compounds.
In these examples, the cores of the molecules are acting as
the incompatible parts mainly because of their shape
(rod/sphere and rod/disk), which can greatly limit the available
molecular designs for the concomitant optimisation of the
morphology of the blend and of the sought aer materials
properties.
2.2 Thermal properties of pure compounds
As reported in the literature, TP6 exhibits a columnar hexagonal
liquid crystalline phase from 69 ꢀC to 99 ꢀC and TP6EO2M
shows only a Cr–Iso transition at 52 ꢀC.21,25 TP6Gall is liquid
In order to demonstrate a more general approach, we have
explored a strategy based on incompatible peripheral chains:
the pendent chains would act as the immiscible elements while
the core of the molecule would provide the function of interest.
Herein, as a model study, we report a novel amphiphile-like
mesogen, TP6Gall, and its use as a compatibilising agent to
stabilise blends of hydrophobic (TP6, 2,3,6,7,10,11-hexahexyl-
oxytriphenylene) and hydrophilic (TP6EO2M, 2,3,6,7,10,11-
hexa(1,4,7-trioxaoctyl)triphenylene) triphenylenes, Scheme 1.
We have chosen triphenylenes as the model aromatic cores
because they are relatively simple to synthesise and are a well-
known class of discotic liquid crystals.20 In this model system,
the opportunity for mesophases (ordered molecules in the bulk)
enables easier characterisation of bulk morphology compared
to amorphous materials.
Blends of TP6Gall (0–50 mol%) with an equimolar
TP6 : TP6EO2M mixture have been studied by polarised optical
microscopy (POM), differential scanning calorimetry (DSC) and
small-angle X-ray scattering (SAXS). While the TP6 : TP6EO2M
mixture results in large incompatible domains of pure TP6 and
pure TP6EO2M, addition of TP6Gall leads to smaller domains
as the quantity of TP6Gall increases. With 50 mol% TP6Gall,
mm-featured interpenetrated networks of crystalline TP6EO2M
and of TP6/TP6Gall mixture are obtained. Interestingly, a single
liquid phase is obtained above the clearing point of the blend
and no macrophase separation is observed upon multiple
temperature cycles between RT and temperature above the
clearing point of the blend: the interpenetrated network is
reliably reformed upon cooling.
ꢀ
crystalline at room temperature with a clearing point at 30 C.
X-ray diffraction prole of TP6Gall shows three peaks (Fig. 1),
which follow a Q-ratio of 2 : O5 : O6 (indexed as (200), (210), and
(211)), indicative of a cubic lattice with a lattice parameter a ¼
˚
33.7 A, which can be ascribed to an extended form of TP6Gall
˚
(ꢁ35 A, inset Fig. 1) with some interpenetration of the pendent
chains.
NAa3r
m ¼
(1)
2M
Using eqn (1) to calculate m, the number of molecules per
micelle for a cubic centred lattice, a value of about 10 molecules
26
˚
per micelle is obtained. With an interdisc distance of ꢁ3.6 A,
˚
the length of the micelle would be 32.4 A, in line with the lattice
parameter. Therefore we attribute the mesophase of TP6Gall to
a centred cubic phase.
When TP6 and TP6EO2M are mixed in an equimolar ratio,‡
macrophase separation is observed and the thermal behaviour
of each phase is similar to the individual components (Table 1).
The POM clearly demonstrates the immiscibility of the two
triphenylenes in the isotropic phase (Fig. 2a). Indeed, two
immiscible liquid phases are observed. Upon cooling this
blend, the isotropic TP6 domain becomes liquid crystalline
around 70 ꢀC (Fig. 2b) then crystalline at ꢁ50 ꢀC. At ꢁ40 ꢀC the
isotropic TP6EO2M domain also becomes crystalline (Fig. 2c).
This behaviour is further supported by XRD analysis (Fig. 3).
The SAXS prole of the blend at 80 ꢀC (Fig. 3d) shows the main
peak corresponding to TP6 in the hexagonal columnar phase
(Fig. 3a). At 60 ꢀC (Fig. 3e) the SAXS prole shows the pattern for
TP6 in the crystalline phase alone (Fig. 3b), while at 25 ꢀC
2 Results and discussion
2.1 Synthesis
‡ All blends have been prepared by dissolving the components in
dichloromethane at the required ratio followed by solvent evaporation and
overnight drying under vacuum. Data discussed are obtained aer heating at
TP6 and TP6EO2M were obtained accordingly to literature
procedures21 with minor modications.22 In particular
TP6EO2M necessitated purication by HPLC to be obtained least once the mixtures above the clearing point.
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Scheme 2 Synthetic strategy for TP6Gall.
Table
1
Phase transition temperatures (ꢀC) and enthalpies (in
brackets, J gꢂ1) determined by DSC. Phases were determined by POM
and SAXS
Sample
2nd heating
Transition
TP6
69 (46)
99 (6)
52a
30 (19)
39 (8)
49 (9)
51 (21)
66 (17)
88a
Cr–Colh
Colh–Iso
Cr–Iso
Cub–Iso
M–M
M–Iso
Cr–Iso (TP6EO2M)
Cr–Colh (TP6)
Colh–Iso (TP6)
TP6EO2M
TP6Gall
TP6 : TP6Gallb
TP6 : TP6EO2Mb
(TP6 : TP6EO2M) : TP6Gallc
95 : 5
52 (19)
66 (16)
85 a
40
Cr–Iso (TP6EO2M)
Cr–Colh (TP6)
Colh–Iso (TP6)
X–X
Fig. 1 SAXS profile of TP6Gall at 25 ꢀC. Inset: MM2 model of TP6Gall.
80 : 20
50
53
63
41
X–X
X–X
X–Iso
M + Cr–X + Cr
X + Cr–Iso
(Fig. 2f) the SAXS pattern is the combination of the patterns for
crystalline TP6 (Fig. 3b) and crystalline TP6EO2M (Fig. 3c).
Upon addition of TP6Gall to the TP6 : TP6EO2M mix, the
behaviour and morphology of the blend is altered. With only
a small amount (5 mol%) of TP6Gall, the blend behaves simi-
larly to the non-doped mixture, yet smaller domains of TP6 and
TP6EO2M can be observed on POM (Fig. S12†) pointing to an
impact of the compatibiliser on the morphology of the blend
already at low concentration. DSC curves (Fig. S13†) and SAXS
patterns (Fig. S14†) do not differ much from the TP6 : TP6EO2M
equimolar blend. No diffraction pattern or transition tempera-
ture corresponding to pure TP6Gall was observed. While it
would be convenient to assume that TP6Gall is well dispersed at
the TP6/TP6EO2M interface, TP6Gall is more likely well mixed
within a TP6-rich domain. Indeed when TP6 and TP6Gall are
mixed in an equimolar ratio, homogeneous mesophases and
isotropic phase are observed (Fig. S21† and SAXS pattern
Fig. 4a), demonstrating that TP6 and TP6Gall are miscible.
Signicant changes were observed with 20 mol% TP6Gall.
Importantly, the size of the domains appears again smaller than
in the TP6 : TP6EO2M mix (Fig. 2a–c) and blends containing
5 mol% TP6Gall (Fig. S12†). Complex textures observed in POM
(Fig. 2e–g) and overlapping phase transitions in DSC (Fig. 2h)
50 : 50
48
From POM. b 50 : 50 mol%. c In mol%. Cr: crystal, Iso: isotropic, Cub:
cubic, Colh: columnar hexagonal, M: unknown mesophase, X: unknown
phase.
a
preclude detailed analysis of this blend. Nevertheless, mainly
two domains can be observed by POM at all temperature,
including aer the clearing point (63 C) with two immiscible
ꢀ
liquid phases. Upon cooling, one of the isotropic domains
forms an unknown LC phase (SAXS pattern in Fig. 4b). No
denite conclusion can be drawn as the SAXS prole resembles
both the prole of crystalline TP6EO2M and the prole of the
TP6 : TP6Gall mix. Upon further cooling to 25 ꢀC, two domains
can be attributed by analysing the SAXS prole (Fig. 4c). First,
a crystalline domain is composed of TP6EO2M. Indeed, the
peaks at 3.33, 4.15, and 5.39 nmꢂ1 (highlighted in blue in
Fig. 4c) are similar to the three peaks observed at 3.37, 4.16, and
5.36 nmꢂ1 for the pure TP6EO2M (Fig. 3c). The composition of
the unknown mesophase is ascribed to a TP6 : TP6Gall mixture
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Fig. 2 TP6 : TP6EO2M equimolar mixtures. Top: with 0 mol% TP6Gall (a) POM image at 90 ꢀC; (b) at 50 ꢀC; (c) at 25 ꢀC; (d) DSC curves of second
heating and second cooling. Middle: with 20 mol% TP6Gall (e) POM image at 70 ꢀC; (f) at 50 ꢀC; (g) at 25 ꢀC; (h) DSC curves of second heating and
second cooling. Bottom: with 50 mol% TP6Gall (i) POM image at 70 ꢀC; (j) at 50 ꢀC; (k) at 25 ꢀC; (l) DSC curves of second heating and second
cooling (10 ꢀC minꢂ1). Single arrow: parallel polarisers, crossed arrows: crossed polarisers.
25 mol% nal composition. The thermal behaviour of this
blend looks much simpler than the 20 mol% case. For the rst
time in this system a single isotropic phase was observed under
ꢀ
POM above the clearing point at 48 C (Fig. 2i). Upon cooling,
micro-segregation of a network of crystalline domains in
a mesophase was observed (Fig. 1j). The crystalline nature of the
network is conrmed as it is readily broken into smaller pieces
when applying pressure on the sample (Fig. 2k).§ As for the
other mixtures, the crystalline phase is composed of TP6EO2M
as seen in the SAXS pattern (Fig. 4d). The unknown mesophase
is again attributed to a TP6 : TP6Gall mixture based on the SAXS
patterns, a relatively narrow peak as 3.49 nmꢂ1 (overlapped with
the signal of TP6EO2M) and a broad peak at 4.50 nmꢂ1 (Fig. 3d).
Compared to the pure TP6 : TP6Gall mixture both peaks are
shied to higher Q values, which is attributed to different
Fig. 3 SAXS patterns of (a) TP6 at 80 ꢀC (LC phase), (b) TP6 at 25 ꢀC
TP6/TP6Gall ratio. The DSC traces (Fig. 2l) are similar to the
(crystal phase), (c) TP6EO2M at 25 ꢀC (crystal phase) and
traces observed for the TP6 : TP6Gall mixture (Fig. S22†) with
two endothermic transitions on heating and two exothermic
transitions on cooling. The rst endothermic transition at 40 ꢀC
has much higher enthalpy than in the TP6 : TP6Gall mixture. It
is attributed to an overlapping transition involving TP6EO2M.
An important difference with previous blends is the
morphology of the present blend, as now TP6EO2M and
TP6/TP6Gall form densely interpenetrating networks at the
a TP6 : TP6EO2M 50 mol% : 50 mol% mixture at (d) 80 ꢀC, (e) 60 ꢀC, (f)
25 ꢀC.
based on the similarity of the peaks at 3.08 and 4.35
(broad) nmꢂ1 (highlighted in green in Fig. 4c), and the pattern
observed for the TP6 : TP6Gall mixture with peaks at 3.12 and
4.40 (broad) nmꢂ1 (Fig. 4a).
Most interesting is the mixture containing 50 mol% TP6Gall
that is with a TP6 25 mol% : TP6Gall 50 mol% : TP6EO2M
§ Mechanical pressure applied with a spatula on the glass covering the sample.
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amount that can be used in the blend does not necessarily need
to be small.
4 Experimental
4.1 Materials
Dichloromethane, hexane, ethanol, methanol, N,N0-dime-
thylformamide (DMF), tetrahydrofurane (THF), acetic acid, and
sulfuric acid were purchased from Fisher. Acetone and ethyl
acetate were purchased from VWR. Diethyl ether was purchased
from Sigma Aldrich. Hydrobromic acid was purchased from Alfa
Aesar. All solvents were used without further purication except
for ethyl acetate, which was distilled in vacuo. Column chro-
matography was carried out on silica gel 60 [Alfa Aesar, 0.040–
0.063 mm]. Reaction progress was followed with TLC plate on
aluminium support (silica: Alugram® SIL G/UV254).
Fig. 4 SAXS pattern of (a) TP6 : TP6Gall equimolar mixture at 25 ꢀC
and (TP6 : TP6EO2M) : TP6Gall mixture (b) with 20 mol% TP6Gall at
60 ꢀC, (c) with 20 mol% TP6Gall at 25 ꢀC, (d) with 50 mol% TP6Gall at
25 ꢀC.
4.2 Equipment
NMR spectra were recorded on Brucker Avance III 400 (1H
400 MHz, 13C 101 MHz) instrument and are reported relative to
the residual solvent as the internal standard (CDCl3: d [1H] ¼
7.26 ppm; d [13C] ¼ 77.16 ppm; DMSO-d6: d [1H] ¼ 2.50 ppm;
d [13C] ¼ 39.52 ppm). Coupling constants are expressed in Hz.
High resolution mass spectra (HRMS) were determined from
Micromass ZABspec mass spectrometer in TOP MS ES+ mode
and are reported as (m/z (%)). IR spectra were recorded on
Perkin Elmer Spectrum 100 FT-IR spectrometer. Polarized
optical microscopy images were recorded on an Olympus C-
CMAD-2 device using a JVC TK-C1380 camera. Heating was
controlled using a Linkam Scientic LTS 350 apparatus. X-ray
diffraction measurements were recorded using a Macor cup
on an Anton Paar PANalytical empyrean X-ray diffractometer
micrometer scale. Furthermore this particular morphology is
well reproducible upon heating–cooling cycles, most likely
because the liquid phase is a single isotropic phase, even if
mechanically challenged during the process.§ On heating, the
crystalline and LC domains melt and a homogenous isotropic
phase is obtained. On cooling from the isotropic phase, the
growing crystals do not aggregate into large domain and stays
well dispersed into the liquid crystalline matrix.
3 Conclusions
˚
equipped with a CuKa X-ray source (l ¼ 1.540598 A). DSC curves
were recorded on a Perkin Elmer DSC 7 device (for ambient to
high temperature) or on a Mettler Toledo DSC 1 STARe System
(for sub-ambient to high temperature). All DSC results shown
are taken during a second heating–cooling cycle. Transition
temperatures are taken at the maximum transition peak.
In conclusion, a novel mesogenic amphiphile, TP6Gall, was
synthesized and its compatibilising behaviour was studied.
TP6Gall shows a cubic liquid crystalline lattice at room
temperature. The blend of two incompatible triphenylenes, the
hydrophobic TP6 and the hydrophilic TP6EO2M, shows mac-
rophase separation and a biphasic liquid phase is obtained
upon heating. On addition of small amount of TP6Gall smaller
domains are observed but macrophase separation still occurs.
4.3 Material synthesis
Ethyl 3,4,5-tris(1,4,7-trioxaoctyl)benzoate (12). A solution of
At higher concentration (50 mol%), TP6 and TP6EO2M micro ethyl gallate (293 mg, 1.61 mmol, 1 equiv.), K2CO3 (2.23 g,
segregate into network of crystalline TP6EO2M in 16.1 mmol, 10 equiv.) and the (3,6-dioxaheptyl)-4-
a
a TP6 : TP6Gall liquid crystalline matrix. Notably, the three- methylbenzenesulfonate (4.5 equiv.) in degassed DMF (10 mL)
ꢀ
component melt is a single isotropic phase and the micro- was stirred at 80 C for 20 h. The solvent was then removed in
segregated network is reliably formed during cooling. We vacuo and the crude ltered through a pad of Celite. DCM was
have therefore demonstrated compatibilisation of two immis- added and the product was extracted with DCM. The organic
cible triphenylenes using TP6Gall. Uniquely we have developed phase was washed with a 1 M solution of HCl, brine, dried over
a system based on incompatibility of peripheral chains instead MgSO4 and the solvent was evaporated. The yellow oil was
of molecular shapes as used in the few published examples of puried by column chromatography (SiO2, DCM/MeOH ¼
1
small molecules compatibilisation. This is expected to be 97 : 3) to afford 12 as a colourless oil (486 mg, 49%). H NMR
advantageous for the development of functional materials (400 MHz, CDCl3) d 7.28 (s, 2H, ArCH), 4.33 (q, J ¼ 7.1 Hz, 2H,
blends, as it allows for greater exibility in the design of the core –CH2OCOR), 4.26–4.17 (m, 6H, –CH2–), 3.89–3.84 (m, 4H, –CH2–),
molecules hence enables simple modication of the properties 3.82–3.78 (m, 2H, –CH2–), 3.74–3.68 (m, 6H, –CH2–), 3.58–3.50
of the nal materials. Importantly, the small molecule compa- (m, 6H, –CH2–), 3.37 (s, 6H, –CH2–), 3.36 (s, 3H, –CH3), 1.36 (t, J ¼
tibiliser acts as a functional structural agent and as such the 7.1 Hz, 3H, CH3CH2OCOR). 13C NMR (101 MHz, CDCl3) d 166.2
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(C]O), 152.4 (2 ArC), 142.6 (ArC), 125.5 (ArC) 109.1 (2 ArCH), acetate followed by evaporation in vacuo of the solvent afforded
72.6 (–CH2–), 72.2 (–CH2–), 72.1 (2 –CH2–), 70.9 (2 –CH2–), 70.7 a orange solid which was puried by column chromatography
(–CH2–), 70.6 (–CH2–), 69.8 (2 –CH2–), 69.0 (2 –CH2–), 61.1 (SiO2, DCM). 016 was obtained as a white solid (105.9 mg, 42%).
(–CH2OCOR), 59.2 (2 –CH3), 59.1 (–CH3), 14.5 (CH3CH2OCOR). 1H NMR (400 MHz, CDCl3) d 7.84 (s, 6H, ArCH), 7.10 (t, J ¼ 8.4 Hz,
HRMS (TOF ES+): m/z [M + Na]+ ¼ 527.2479 (calculated: 1H, ArCH), 6.50–6.44 (m, 1H, ArCH), 6.43–6.37 (m, 2H, ArCH),
527.2468), [M + K]+ ¼ 543.5.
4.99 (s, 1H, –OH), 4.23 (t, J ¼ 6.6 Hz, 12H, –OCH2), 3.95 (t, J ¼ 6.4
3,4,5-Tris(1,4,7-trioxaoctyl)benzyl chloride (14). To a stirred Hz, 2H, –OCH2), 2.02–1.88 (m, 12H, –CH2–), 1.88–1.77 (m, 2H,
suspension of LiAlH4 (200 mg, 5.15 mmol, 1.3 equiv.) in dry THF –CH2–), 1.67–1.51 (m, 14H, –CH2–), 1.47–1.32 (m, 20H, –CH2–),
(4 mL) was added a solution of 12 (2.00 g, 3.96 mmol, 1 equiv.) 1.01–0.86 (m, 15H, –CH3). 13C NMR (101 MHz, CDCl3) d 160.6,
in dry THF (8 mL) at 0 ꢀC under argon atmosphere. The mixture 156.9, 149.2, 149.1, 149.1, 149.1, 130.2, 123.9, 123.9, 123.8, 107.8,
was brought back to room temperature, stirred for 3 h and was 107.6, 107.1, 102.2, 69.9, 68.0, 31.8, 29.6, 29.3, 26.1, 26.0, 14.2.
then quenched by addition of successively isopropyl alcohol HRMS (TOF ES+): m/z [M] ¼ 936.6451 (calculated: 936.6479).
(1 mL), cold water (3 mL) and a 30% aqueous solution of
TP6Gall (17). A solution of 14 (163 mg, 0.339 mmol, 3 equiv.),
sodium hydroxide (1 mL). Aer ltration of the crude, the 16 (105.9 mg, 0.113 mg, 1 equiv.) and K2CO3 (47 mg,
product was extracted with ethyl acetate, washed with brine, 0.339 mmol, 3 equiv.) in degassed DMF (5 mL) was stirred under
ꢀ
dried over MgSO4, and the solvent was evaporated in vacuo to argon at 120 C for 24 h. The solvent was evaporated in vacuo.
afford the reduced 3,4,5-tris(1,4,7-trioxaoctyl)benzyl alcohol as The product was extracted with ethyl acetate (ꢃ3), dried over
a light yellow oil (1.137 g, 62%).
MgSO4 and the solvent was evaporated in vacuo. Purication by
To a solution of 3,4,5-tris(1,4,7-trioxaoctyl)benzyl alcohol column chromatography (SiO2, neat DCM to DCM/MeOH ¼
(200 mg, 0.43 mmol, 1 equiv.) in dry DCM (25 mL) was added 97.5: 2.5) afforded TP6Gall as an off-white solid in a 87% yield.
dropwise a solution of SOCl2 (320 mL, 4.3 mmol, 10 equiv.) in dry 1H NMR (400 MHz, CDCl3) d 7.83 (s, 6H), 7.19–7.13 (m, 1H), 6.65
DCM (10 mL) at room temperature. The solution was stirred at (s, 2H), 6.56–6.50 (m, 3H), 4.90 (s, 2H), 4.23 (t, J ¼ 6.5 Hz, 12H),
room temperature for 3 h. The solvent was evaporated in vacuo, 4.20–4.13 (m, 6H), 3.97 (t, J ¼ 6.5 Hz, 2H), 3.88–3.83 (m, 4H),
1
affording 14 in a quantitative yield. H NMR (400 MHz, CDCl3) 3.83–3.78 (m, 2H), 3.74–3.68 (m, 6H), 3.58–3.53 (m, 6H), 3.38 (s,
d 6.62 (s, 2H, ArCH), 4.48 (s, 2H, Ar–CH2–Cl), 4.21–4.12 (m, 6H, 3H), 3.37 (s, 6H), 2.01–1.89 (m, 12H), 1.89–1.81 (m, 2H), 1.63–
Ar–O–CH2–), 3.89–3.83 (m, 4H, –CH2–), 3.82–3.77 (m, 2H, –CH2–), 1.53 (m, 12H), 1.44–1.33 (m, 22H), 0.97–0.89 (m, 15H). 13C NMR
3.74–3.69 (m, 6H, –CH2–), 3.60–3.52 (m, 6H, –CH2–), 3.38 (s, 6H, (101 MHz, CDCl3) d 160.5, 160.1, 152.9, 149.1, 132.6, 130.0,
–CH3), 3.38 (s, 3H, –CH3). 13C NMR (101 MHz, CDCl3) d 152.8 123.7, 107.7–106.9, 102.0, 72.8–68.0, 59.2, 31.8, 29.6, 29.4, 26.2,
(3 ArC), 132.9 (ArC), 108.4 (2 ArCH), 72.5 (–CH2–), 72.2 (–CH2–), 26.0, 22.8, 14.2. HRMS (TOF ES+): m/z [M + Na]+ ¼ 1403.8754
72.2 (2 –CH2–), 70.9 (2 –CH2–), 70.7 (–CH2–), 70.6 (–CH2–), 69.9 (calculated: 1403.8736).
(2 –CH2–), 69.1 (2 –CH2–), 59.2 (3 –CH3), 46.7 (Ar–CH2–Cl). HRMS
(TOF ES+): m/z [M + Na]+ ¼ 503.2005 (calculated: 503.2024). IR:
Acknowledgements
(neat)/cmꢂ1 2925, 2876, 2823; 1591, 1504 (aromatic ring stretch);
1333 (aromatic ether 4–O–C); 1101 (aliphatic ether).
We thank the School of Metallurgy and Materials (University of
2-(6-Bromohexyloxy)-3,6,7,10,11-pentahexyloxytriphenylene Birmingham) for access to its analytical facility for DSC studies
(15). A solution of 11 (192 mg, 0.27 mmol, 1 equiv.), K2CO3 and Dr Martin Hollamby for helpful discussions. AJH thanks
(75 mg, 0.54 mmol, 2 equiv.) and 1,6-dibromohexane (200 mL, the School of Chemistry, University of Birmingham, for
1.34 mmol, 5 equiv.) in degassed DMF (1 mL) was stirred at a studentship, and the EPSRC for underpinning support.
120 ꢀC for 21 h under argon. DMF was then evaporated in vacuo
and the resulting dough was ltrated through a pad of Celite
and washed with DCM. Solvent was evaporated and the
Notes and references
resulting solid was recrystallised from ethanol to afford 15 as
an off-white solid (140.3 mg, 57%). 1H NMR (400 MHz, CDCl3)
d 7.83 (s, 6H, ArCH), 4.23 (t, J ¼ 6.6 Hz, 12H, Ar–O–CH2–), 3.45
(t, J ¼ 6.8 Hz, 2H, –CH2–Br), 2.00–1.86 (m, 14H, –CH2–), 1.68–
1.50 (m, 14H, –CH2–), 1.49–1.30 (m, 20H, –CH2–), 1.00–0.87 (m,
15H, –CH3–). 13C NMR (101 MHz, CDCl3) d 149.1, 149.0, 123.9,
123.8, 123.7, 107.5, 107.4, 69.9, 69.8, 69.6, 33.9, 32.9, 31.8, 31.1,
29.6, 29.5, 28.1, 26.0, 25.6, 22.8, 14.2. HRMS (TOF ES+): m/z [M
+ H]+ ¼ 909.5374 (calculated: 909.5373).
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