Hydrogen-bonded bent-core blue phase liquid crystal complexes containing various molar ratios of proton acceptors and donors

Article abstract of DOI:10.1039/c5ra26827c

Various hydrogen-bonded (H-bonded) bent-core liquid crystal complexes consisting of pyridyl and benzoic acid derivatives were synthesized and compared with their covalent analogues in this study. The molar ratios of pyridyl and benzoic acid derivatives could be tuned to form various H-bonded liquid crystal (LC) diads (with 1:1 molar ratio of H-acceptors T and H-donors D) and complexes (with different molar ratios of T and D). By insertion of H-bonds into different positions of bent-core supramolecules, the mesophasic properties of H-bonded bent-core LC complexes were optimized, which could facilitate the most suitable LC components and compositions to be utilized in H-bonded blue phase (BP) LC complexes. In BPLC complexes, the molar ratios, alkyl chain lengths, the lateral fluoro-substitution and the chiral center of H-bonded bent-core supramolecules would affect the temperature ranges of BPs. Accordingly, H-bonded bent-core complex P_IIIC₉/A_IIF? (3/7 mol mol^-1) displayed the widest BPI range of ΔT_BPI = 12.0 °C at the correspondent H-acceptor T = P_IIIC₉ and H-donor D = A_IIF?. Since the covalent-bonded bent-core mixture only had narrow ranges of BPIII, we could summarize that the introduction of H-bonds into the bent-core center effectively stabilizes the BPs and easier induces the BPI.

Full text of DOI:10.1039/c5ra26827c

View Article Online
View Journal
RSC Advances
This article can be cited before page numbers have been issued, to do this please use: C. Han, Y. Chou,
S. Chen and H. Lin, RSC Adv., 2016, DOI: 10.1039/C5RA26827C.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. This Accepted Manuscript will be replaced by the edited,
formatted and paginated article as soon as this is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/advances

Page 1 of 10
RSC Advances
View Article Online
DOI: 10.1039/C5RA26827C
RSC Advances
RSCPublishing
ARTICLE
Hydrogen-bonded bent-core blue phase liquid crystal
complexes containing various molar ratios of proton
acceptors and donors
Cite this: DOI: 10.1039/x0xx00000x
Chun-Chieh Han, Yu-Chaing Chou, San-Yuan Chen and Hong-Cheu Lin*
Received 00th January 2012,
Accepted 00th January 2012
Various hydrogen-bonded (H-bonded) bent-core liquid crystal complexes consisting of pyridyl
and benzoic acid derivatives were synthesized and compared with their covalent analogues in
this study. The molar ratios of pyridyl and benzoic acid derivatives could be tuned to form
DOI: 10.1039/x0xx00000x
www.rsc.org/
various H-bonded liquid crystal (LC) diads (with 1:1 molar ratio of H-accepters
T and H-donors
D
) and complexes (with different molar ratios of T and D). By insertion of H-bonds into
different positions of bent-core supramolecules, the mesophasic properties of H-bonded
bent-core LC complexes were optimized, which could facilitate the most suitable LC
components and compositions to be utilized in H-bonded blue phase (BP) LC complexes. In
BPLC complexes, the molar ratios, alkyl chain lengths, the lateral fluoro-substitution and the
chiral center of H-bonded bent-core supramolecules would affect their temperature ranges of
BPs. Accordingly, H-bonded bent-core complex PIIIC9/AIIF* (3/7 mol/mol) displayed the widest
BPI ranges of ∆TBPI = 12.0°C at the correspondent H-accepter
T = PIIIC9 and H-donor D = AIIF*.
Since the covalent-bonded bent-core mixture only had narrow ranges of BPIII, we could
summarize that the introduction of H-bonds in the bent-core center effectively stabilize the
BPs and easier induce the BPI.
dimensional BP lasers15ꢀ17 and tunable photonic band gap
materials.18ꢀ20 However, the main defect of BPs is the narrow
Introduction
With the chiral nematic (N*) phase induced by the chiral
effects of molecular structures, the blue phases (BPs) are the
special forms of the chiral nematic phase. The molecular
structures of the BPs consist of double twist cylinders
(DTCs),1,2 and the BPs materials often have high chiralities.
According to previous researches (e.g., the Kossel diagram
method,3,4 Landau theory5,6 and the polarized optical
microscopy), the BPs can be categorized into three types: BPI,
BPII and BPIII with bodyꢀcentered cubic, simple cubic and
amorphous symmetric structures, respectively.7ꢀ10 Since the BPs
(e.g., BPI and BPII) possess optically exotic structures,
exhibiting no birefringence but selective reflection of
circularodꢀlikey polarized light,11,12 the BPs are utilized on new
applications of liquid crystals (LCs), such as fast light
modulators, largeꢀscreen flat panel displays,13,14 threeꢀ
stable temperature range, usually less than a few degrees (°C)
between the isotropic and chiral nematic phases upon cooling.21
Accordingly, several methods were applied to introduce or extend
the temperature ranges of BPs by the addition of external materials
(e.g., reactive monomers22ꢀ25 and nanoparticles.26,27
) or the
introduction of biaxialities to LC materials (e.g., bentꢀcore LCs,28ꢀ32
hydrogenꢀbonded LCs33ꢀ35 and LC diads.36ꢀ39). In addition, some
other methods, including the techniques of supercooled freezing,40
discotic LCs41 and light induction,42,43 were also utilized. Therefore,
not only developing single components with broad BP ranges are
significant,44ꢀ46 but also applying different mixture techniques to
extend BP ranges are important. Because of this reason, the
interactions of individual components in LC mixtures are of interest
to optimize the BP ranges effectively.
Previously, bentꢀcore liquid crystal materials were widely applied
in ferroelectric LC materials,47 organic/inorganic composites48,49 and
chiral nanostructures.50ꢀ52 Recently, the introduction of biaxialities to
Department of Materials Science and Engineering, National Chiao Tung University, LC materials, such as: bentꢀcore and diꢀmesogenic LCs, can induce
Hsinchu, Taiwan. Fax: (+886)35724727 E-mail: linhc@mail.nctu.edu.tw
BPs in LC mixtures. In general, the BPLC mixtures often consist of
LC hosts and chiral dopants, where the utilized LC hosts are
generally the nematic or chiral nematic phases. Since the nematics of
bentꢀcore molecules have special properties compared with the
Footnotes relating to the title and/or authors should appear here.
Electronic Supplementary Information (ESI) available: [details of any supplementary
information available should be included here]. See DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 2013
J. Name., 2013, 00, 1-3 | 1

RSC Advances
Page 2 of 10
VJieowuArrtnicalelONnlainme e
ARTICLE
DOI: 10.1039/C5RA26827C
nematics of rodꢀlike molecules, such as: (a) an increase of twisting were determined by differential scanning calorimetry (DSC,
power in the N* phase by the introduction of achiral bentꢀcore model: Perkin Elmer Pyris 7) under N2 at a heating and cooling
molecules,53,54 and (b) many research results suggested the biaxial rate of 0.5°C minꢀ1. Fourier transform infrared (FTIR) spectra
shape (e.g., bentꢀcore) of the molecules is responsible for the were recorded on a PerkinElmer spectrum 1000. The UVꢀVis
stabilization of DTC structures.55ꢀ57 Therefore, the bentꢀcore spectra were recorded on a JASCO Vꢀ670 spectrometer with 2
molecules are widely used in BPLC mixtures as LC hosts or chiral nm resolution at room temperature.
dopants.
Preparation of materials
The synthesis of covalentꢀbonded bentꢀcore molecule
The hydrogen bonds are generated by the attractions of
proton donors and acceptors between complimentary
polar units intermolecularly or intramolecularly.58,59 The
intermolecular hydrogen bonds of supramolecules can be
formed by Hꢀacceptors (e.g., pyridine) and Hꢀdonors (e.g.,
acid).60ꢀ62 However, dimeric supramolecules can be formed by
selfꢀintermolecular hydrogenꢀbonds between two acid moieties
of the same molecular structure. Therefore, the Hꢀbonded LC
mixtures can be formed via selfꢀassembly of supramolecular
force with diversified molecular structures via Hꢀbonds. In
addition, the proportions of Hꢀbonded LCs covered various
molar ratios (0ꢀ100 mol%), and the compatibility between
different components also can be solved. In the previous
research, the Hꢀbonds can not only generate soft functional
segments in LC materials, but also offer stabilized BPLCs.64ꢀ66
Moreover, the location of Hꢀbonds (i.e., the inserted positions
of Hꢀbonds in molecules) can monitor the phase transitions and
temperature ranges of LCs (including bentꢀcore LCs).67ꢀ69
In this study, we synthesized two covalentꢀbonded bentꢀcore
molecules and several series of Hꢀbonded bentꢀcore
supramolecules containing four pyridyl and benzoic acid
derivatives for this study. The molar ratios of pyridyl and
benzoic acid derivatives could be tuned to form various LC
complexes with overꢀsupplied benzoic acids behaving as rodꢀ
like dimers. By insertion Hꢀbonds into different positions of the
bentꢀcore supramolecules, the mesophasic properties of Hꢀ
bonded bentꢀcore molecules were optimized, which could
facilitate the most suitable LC components and compositions to
be utilized in the Hꢀbonded BPLC complexes. In the BPLC
complexes, the molar ratios, alkyl chain lengths, the lateral
fluoroꢀsubstitution and the chirality of Hꢀbonded bentꢀcore
molecules will be discussed for their influences on the
temperature ranges of BPs.
(
PIIIC9AIIF*), pyridyl derivative (PIIIC9), and benzoic acid
derivative (AIIF*) were shown in Scheme 1.
O
O
O
OH
(a)
O
O
OBn
O
O
C9H19
O
Br
HO
OBn
HO
OH
C9H19
O
K2CO3, acetone, reflux
DCC, DMAP, DCM, r.t.
O
HO
O
F
O
(R)
O
O
O
O
OH
2
H2, Pd/C
O
THF, r.t.
1
DCC, DMAP, DCM, r.t.
C9H19O
O
O
O
O
O
O
F
(R)
O
O
PIIIC9AIIF*
C9H19
O
O
O
O
O
(b)
C
H
9
Br
19
KOH
MeOH, reflux
OH
OMe
OMe
K
CO , KI, acetone, reflux
3
2
C
H O
9 19
C
H
O
9
19
HO
O
O
O
O
OH
O
OBn
H
, Pd/C
OBn
2
THF, r.t.
O
O
HO
C
H O
19
9
C H O
9 19
DCC, DMAP, DCM, r.t.
3
O
N
O
O
N
HO
O
DCC, DMAP, DCM, r.t.
P
C
9
III
C
H O
9 19
(c)
O
F
O
F
O
F
O
F
Br
,
NaOH
Toluene, H SO
BBr
2
2
4
3
HO
H
HO
MeO
o
o
1,4ꢀdioxane,
0
C
DCM, r.t.
MeOH, 80
C
OMe
OMe
OH
O
OH
(S)
F
O
F
HO
(R)
(R)
KOH
HO
MeO
MeOH, reflux
o
0 C
PPh , DIAD, THF,
3
O
O
O
O
O
BnO
BnO
O
F
HO
O
F
OH
H
, Pd/C
2
(R)
(R)
O
THF, r.t.
O
DCC, DMAP, DCM, r.t.
O
4
O
A
F*
II
Scheme 1 Synthesis of (a) covalentꢀbonded bentꢀcore molecule
PIIIC9AIIF*), (b) Hꢀaccepter (PIIIC9) and (c) Hꢀdonor (AIIF*). (The
(
additional synthetic details are shown in Schemes S1ꢀS3.)
Experimental
(i) Covalent-bonded bent-core molecule PIIIC9AIIF*.
A
Chemical analysis
1H NMR spectra were recorded on a Bruker Unity 300 MHz
spectrometer using CDCl3 as solvent. Elemental analyses (EA)
were performed on a Heraeus CHNꢀOS RAPID elemental
analyzer.
mixture of compound
1
(5.67g, 11.9mmole), compound
2
(4.62g, 11.9mmole), DMAP (0.18 g, 1.5 mmole) and DCC
(4.11 g, 19.8mmol) was dissolved in dry DCM under nitrogen
for 16 h at room temperature. After work up, the solvent was
extracted with water/DCM and organic liquid layer was dried
over anhydrous magnesium sulphate. After removal of the
solvent by evaporation under reduced pressure, the residue was
purified by column chromatography and recrystallized from
Liquid-crystalline and physical properties
Mesophasic textures of all Hꢀbonded dimeric bentꢀcore
complexes and Hꢀbonded mixtures were characterized by
polarizing optical microscopy (POM) using a Leica DMLP
equipped with a temperature control hot stage (Mettler Toledo
FP82HT). Temperatures and enthalpies of phase transitions
DCM/
as a white solid in 80% yield. 1H NMR (300 MHz, CDCl3): δ
(ppm) 8.25 (d, = 8.4 Hz, 4H, ArꢀH),8.13 (d, = 8.7 Hz, 2H,
nꢀhexane to afford compound PIIIC9AIIF* was obtained
J
J
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 3 of 10
Journal Name
RSC Advances
View ArticAle ROnTliInCeLE
DOI: 10.1039/C5RA26827C
ArꢀH), 7.99 (t,
ArꢀH), 7.36 (d,
J
J
= 8.7 Hz, 1H, ArꢀH),7.46 (t,
= 8.4 Hz, 4H, ArꢀH), 7.18 (m, 3H,ArꢀH), 7.13 Roman (
J
= 8.4 Hz, 1H, where
A
I
,
*
,
F
,
P
and subscripts of Arabic (5, 7 and 9) and
, II and III) numerals denote the acid, chiral, fluoro,
(d,
1H, ꢀOCHꢀ), 4.03 (t,
26H, ꢀCH2ꢀ), 0.87 (m, 6H, ꢀCH3). Anal. calcd for C51H55FO10: analogues PIIIC5AIIF* and PIIIC9AIIF* (see Fig. 1b) were also
J
= 8.7 Hz, 2H, ArꢀH), 6.75ꢀ6.64 (m, 2H, ArꢀH), 4.43(m, pyridyl moieties, carbon numbers and phenyl ring numbers,
J
= 6.5 Hz, 2H, ꢀOCH2ꢀ), 1.49ꢀ1.23 (m, respectively. In addition, two covalentꢀbonded bentꢀcore
C, 72.32, H, 6.55; found: C, 73.19, H, 6.97%.
synthesized to be prepared in this study. As the molar ratio of
proton acceptor and donor is equal to 1:1, these Hꢀbonded bentꢀ
core supramolecular complexes were selfꢀassembled to form
supramolecular diads, i.e., T/D = 1/1 mol. In the meanwhile,
(ii) H-accepter PIIIC9. A mixture of compound
3 (4.58g,
11.9mmole), 3ꢀhydroxypyridine (1.13 g, 11.9 mmole), DMAP
(0.18 g, 1.5 mmole) and DCC (4.11 g, 19.8mmol) was
dissolved in dry DCM under nitrogen for 16 h at room
temperature. After work up, the solvent was extracted with
water/DCM and organic liquid layer was dried over anhydrous
magnesium sulphate. After removal of the solvent by
evaporation under reduced pressure, the residue was purified by
the proton donors
D will be selfꢀassembled to generate Hꢀ
bonded rodꢀlike dimmers (see Fig. 1c).
O
O
(a)
O
O
O
O
F
N
O
HO
O
O
(R)
AIF*
PIVC9
column chromatography and recrystallized from DCM/nꢀ
O
O
hexane to afford compound PIIIC9 was obtained as a white solid
in 69% yield. H NMR (300 MHz, CDCl3): δ (ppm) 8.56 (m,
N
O
O
HO
O
Y
1
O
O
X
2H, ArꢀH), 8.29 (d,
2H, ArꢀH), 7.64 (m, 1H, ArꢀH), 7.40ꢀ7.25 (m, 3H, ArꢀH), 6.98
(d, = 9.0 Hz, 2H, ArꢀH), 4.05 (t, = 6.5 Hz, 2H, ꢀOCH2ꢀ),
1.85ꢀ1.78 (m, 2H, ꢀCH2ꢀ), 1.548ꢀ1.22 (m,12H, ꢀCH2ꢀ), 0.90 (t,
= 6.3 Hz, 3H, ꢀCH3). Anal. calcd for C28H31NO5: C, 72.86, H,
6.77, N, 3.03; found: C, 72.85, H, 6.86, N, 3.22%.
J = 9.0 Hz, 2H, ArꢀH), 8.15 (d, J = 9.0 Hz,
H3
C (CH2) O
O
n
P
IIIC5: n=4
AII*: X=CH3(R), Y=H
AIIF*: X=CH3(R), Y=F
AIIF: X=H, Y=F
PIIIC7: n=6
PIIIC9: n=8
J
J
O
O
J
(b)
O
O
O
O
O
F
O
H3
C
(CH )
2 n
O
O
(R)
PIIIC5AIIF*: n=4
PIIIC9AIIF*: n=8
(iii) H-donor AIIF*. Into a 500 ml round bottom twoꢀneck
Y
X
flask compound
4 (10 g, 20 mmole) and 15% Pd/C (1.5 g)
O
O
(c)
OH
O
HO
O
catalyst were stirred in THF (200 ml) under hydrogen at room
temperature for overnight. The catalyst was removed by
filtration through Celite and washed with THF. The solvent was
removed by evaporation under reduced pressure and the crude
product recrystallized by THF/n-hexane to give white solid of
O
O
O
O
Y
AII*: X=CH3(R), Y=H
AIIF*: X=CH3(R), Y=F
X
Fig. 1 Molecular structures of (a) Hꢀbonded bentꢀcore supramolecular
complexes T/D with various ratios of Hꢀacceptors T and Hꢀdonors D, where
T = PIVC9, PIIIC5, PIIIC7 and PIIIC9; D = AIF*, AIIF, AII* and AIIF*, (b)
covalentꢀbonded bentꢀcore analogues PIIIC5AIIF* and PIIIC9AIIF*, (c) Hꢀ
bonded rodꢀlike dimers D.
1
AIIF*, yield 92%. H NMR (300 MHz, CDCl3): δ ( ppm ) 8.16
(d,
(m, 2H, ArꢀH), 6.74 (dd,
11.7 Hz, 1H, ArꢀH), 4.42 (m, 1H, ꢀOCHꢀ), 1.71ꢀ1.60 (m, 2H, ꢀ
CH2ꢀ), 1.33ꢀ1.27 (m, 11H, ꢀCH2CH3), 0.86 (t, = 6.3 Hz, 3H, ꢀ
J
= 8.7 Hz, 2H, ArꢀH), 8.03 (t,
J = 8.0 Hz, 1H, ArꢀH), 7.32
J
= 9.0 Hz, 1H, ArꢀH), 6.68 (dd,
J =
J
Mesophasic properties
CH3). Anal. calcd for C22H25FO5: C, 68. 03, H, 6.49; found: C,
67.78, H, 6.44%. The remaining compounds and experimental
procedures were shown in supporting information.
The phase transition temperatures, enthalpies and mesophasic
ranges of all Hꢀbonded bentꢀcore diads T/D (1/1) are
demonstrated in Tables 1 and S1, which were characterized by
differential scanning calorimetry (DSC) and polarizing optical
microscopy (POM). The transition temperatures of blue phase I
(BPI) – chiral nematic phases (N*) was determined by POM (at
a cooling rate of 0.5°C minꢀ1) due to their undetectable enthalpy
changes by DSC upon cooling. The Hꢀbonded bentꢀcore diads
T/D (1/1) were selfꢀassembled by two complimentary
Preparation of samples
All Hꢀbonded dimeric bentꢀcore complexes and Hꢀbonded
mixtures were constructed by mixing appropriate molar ratios
of Hꢀacceptors and Hꢀdonors in solutions of dry THF, which
were selfꢀassembled into Hꢀbonded supramolecules or mixtures
by evaporating solvents slowly.
components of Hꢀacceptors (
stronger interactrion of –OH…N to replace –OH…C=O– of selfꢀ
dimeric Hꢀdonors. Since the overꢀsupplied proton acceptors
T) and Hꢀdonors (D) with a
Results and discussion
T
will eliminate the liquid crystallinity of supramolecular
complexes (T/D), only the improved mesophasic properties of
Several series of Hꢀbonded bentꢀcore supramolecular
complexes (T/D) were synthesized and prepared by mixing
overꢀsupplied proton donors
are of our concern, which is because the overꢀsupplied proton
donors will be selfꢀassembled to generate Hꢀbonded rodꢀlike
D in supramolecular complexes
different molar ratios of proton acceptors
derivatives) and proton donors (benzoic acid derivatives). As
shown in Fig. 1a, these supramolecular complexes (T/D
T (pyridyl
D
D
dimmers coexisting with their miscible supramolecular diads.
The configurational influences of various Hꢀbonded bentꢀcore
diads (T/D = 1/1) and Hꢀbonded complexes (T/D ≠ 1/1),
)
consist of four proton acceptors
PIIIC9) and four proton donors
T
(
PIVC9
,
PIIIC5
,
PIIIC7 and
D
(
AIF*
,
AIIF
,
AII* and AIIF*),
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 3

RSC Advances
Page 4 of 10
ARTICLE
VJieowuArrtnicalelONnlainme e
DOI: 10.1039/C5RA26827C
Table 1 Phase transition temperatures (°C) and enthalpies (J gꢀ1)a,b of
Hꢀbonded bentꢀcore diads and covalentꢀbonded bentꢀcore analogue
upon cooling.
(ii) H-bonded bent-core complexes PIIIC5/AIIF*, PIIIC7/AIIF*
and PIIIC9/AIIF* (where T = PIIIC5, PIIIC7 and PIIIC9 with
different alkyl chain lengths; D = AIIF*).
Phase transition temperature upon
Complex
cooling
Since the Hꢀbonded bentꢀcore diad PIIIC9/AIIF* revealed the
widest chiral nematic phase range, we tried to improve the
(
°C) [enthalpies (KJ mol-1)]
(mol/mol)
mesophasic properties by the overꢀsupply of proton donor
AIIF* in the analogous supramolecular complexes (T =
PIIIC5/AIIF* PIIIC7/AIIF* and PIIIC9/AIIF*) with different
alkyl chain lengths, where the overꢀsupplied proton donor
AIIF* will be selfꢀassembled to generate Hꢀbonded rodꢀlike
dimmers coexisting with their miscible supramolecular diads.
As shown in Figs. 2(a)ꢀ2(c), the Hꢀbonded bentꢀcore complexes
D =
Iso 110.6°C [1.98] K
PIV
C
9/AIF* = 1:1
Iso 92.7°C [1.34] N* 62.3°C [1.64] K
Iso 101.3°C [1.03] N* 87.6°C [1.48] K
Iso 127.3°C [3.51] K
PIII
C
9/AIIF* = 1:1
,
PIII
C
9/AII* = 1:1
9AIIF*
PIII
C
aPeak temperatures in DSC profiles obtained during the first cooling at
a rate of 1°C minꢀ1. bIso = isotropic phase; N* = chiral nematic phase; K
= crystalline phase.
T/D (where
T = PIIIC5, PIIIC7 and PIIIC9; D = AIIF*) were
prepared with various molar ratios of excessive Hꢀdonor AIIF*
We can summarize the following effects on the mesophasic
ranges of blue phases for all Hꢀbonded bentꢀcore complexes
.
including numbers of aromatic rings, positions of Hꢀbonds,
alkyl chain lengths of Hꢀacceptors
T, and chiral center along
with lateral fluoro substituent of Hꢀdonors
properties are discussed as follows:
D, on mesophasic
PIIIC5/AIIF*
different alkyl chain lengths of Hꢀaccepters
donor AIIF*, i.e., molar ratio effects of Hꢀdonor and Hꢀ
,
PIIIC7/AIIF* and PIIIC9/AIIF* containing
T
and the same Hꢀ
D
=
acceptors; symmetry effects of alkyl chain lengths on Hꢀdonor
and Hꢀacceptors; alkyl chain length effects of Hꢀacceptors;
effects of covalentꢀ and Hꢀbonded bentꢀcore mixtures.
(i) H-bonded bent-core diads PIVC9/AIF*, PIIIC9/AIIF*,
PIIIC9/AII* (where T/D = 1:1) and the covalent-bonded bent-
core analogue PIIIC9AIIF*. As shown in Table 1, Hꢀbonded
bentꢀcore diads PIVC9/AIF* and PIIIC9/AIIF* had similar
chemical structures as their covalentꢀbonded bentꢀcore
analogue PIIIC9AIIF*, but the positions of Hꢀbonds in Hꢀ
bonded bentꢀcore diads PIIIC9/AIIF* and PIVC9/AIF* are
different, where the Hꢀbond of PIIIC9/AIIF* was near the center
of the bentꢀcore structure. The Hꢀbonded bentꢀcore diad
PIVC9/AIF* didn’t possess LC phases upon both heating and
cooling, and its isotropization point (110.6°C) was higher than
that (92.7°C) of PIIIC9/AIIF*. However, the Hꢀbonded bentꢀ
(a) Molar ratio effects of H-donor and H-acceptors. Since all
Hꢀbonded bentꢀcore diads PIIIC5/AIIF*
, PIIIC7/AIIF* and
PIIIC9/AIIF* (where T/D = 1:1) do not possess any BP phases,
the Hꢀbonded bentꢀcore complexes T/D were compared with
various molar ratios of excessive Hꢀdonor AIIF*. As shown in
Figs. 2(a)ꢀ2(c), the BPI was induced in all Hꢀbonded bentꢀcore
complexes PIIIC5/AIIF*, PIIIC7/AIIF* and PIIIC9/AIIF* at the
molar ratios of Hꢀdonor AIIF* ranging 55ꢀ75 mol%, 55ꢀ70
mol% and 55ꢀ80 mol%, respectively. The BPI ranges showed a
tendency of increasing first then decreasing later from 55 mol%
core diad PIIIC9/AIIF* had a very wide chiral nematic phase to 70ꢀ80 mol% of Hꢀdonor AIIF*, and PIIIC9/AIIF* had the
widest molar ratios (55ꢀ80 mol%) of Hꢀdonor AIIF* to present
the BPI. Among these Hꢀbonded bentꢀcore complexes with
excessive Hꢀdonor AIIF*, PIIIC9/AIIF* possessed the widest
BPI range of ∆TBPI = 12.0°C at AIIF* = 70 mol%. In addition,
more information of Hꢀbonded bentꢀcore complexes PIVC9/AIF*
with various molar ratios of Hꢀdonor AIF* is shown in Fig. S1,
where no BP phase is observed if the Hꢀbonded position is
away from the bentꢀcore center. Hence, the slightly excessive
Hꢀdonor AIIF* would increase the chiral concentration to
with a phase range wider than 30°C upon cooling. Hence, the
Hꢀbond near the center of the bentꢀcore structure in Hꢀbonded
bentꢀcore diad PIIIC9/AIIF* generated a softer Hꢀbonded
linkage than that far away from the center (with a more rigid
bent core) in Hꢀbonded bentꢀcore diad PIVC9/AIF*, and the
reduced ordered bentꢀcore stacking of Hꢀboned diad
PIIIC9/AIIF* would facilitate the mesophasic formation more
easily. The effects of the lateral fluoroꢀsubstitution on Hꢀboned
diad PIIIC9/AIIF* was compared with the analogous Hꢀbonded
diad PIIIC9/AII* (without fluoroꢀsubstitution). As expected, the
Hꢀbonded diad PIIIC9/AIIF* with the lateral fluoroꢀsubstitution
had a wider chiral nematic phase range (∆TN* = 30.4°C) and
induce BPI in all Hꢀbonded bentꢀcore complexes PIIIC5/AIIF*
,
PIIIC7/AIIF* and PIIIC9/AIIF*, but high molar ratios Hꢀdonor
AIIF* over 80 mol% would cause the disappearance of the BPI
due to the biaxial dilution of the overꢀsupplied uniaxial rodꢀlike
dimer AIIF*
.
lower phase transition temperatures than PIIIC9/AII* (∆TN*
=
(b) Alkyl chain length effects of H-acceptors. Among all Hꢀ
bonded bentꢀcore complexes in Figs. 2(a)ꢀ2(c), PIIIC7/AIIF*
possesses the BPI phase with the narrowest molar ratio ranges
of Hꢀdonor AIIF* (i.e., 55ꢀ70 mol%) due to the symmetrical
alkyl chain length on both Hꢀdonor AIIF* and Hꢀacceptor
PIIIC7. Comparing Hꢀbonded bentꢀcore complexes PIIIC5/AIIF*
and PIIIC9/AIIF* with asymmetrical alkyl chain lengths, the
molar ratio ranges of Hꢀdonor with BPI (55ꢀ75 mol% and 55ꢀ80
mol%, respectively) were also extended by increasing the alkyl
chain length of Hꢀacceptor. Furthermore, Hꢀbonded bentꢀcore
13.7°C). Compared with Hꢀbonded bentꢀcore diads PIVC9/AIF*
and PIIIC9/AIIF*, the covalentꢀbonded bentꢀcore analogue
PIIIC9AIIF* didn’t show any LC phases upon both heating and
cooling, and PIIIC9AIIF* had the highest isotropization
temperature at 127.3°C due to the highest rigidity of its
covalent structure. Not only the positions of Hꢀbonds but also
the lateral fluoroꢀsubstitution affected the chiral nematic phase
range in Hꢀbonded bentꢀcore diads T/D (1:1). Therefore, the Hꢀ
bonded bentꢀcore diad PIIIC9/AIIF* illustrated the widest chiral
nematic phase range and lowest phase transition temperatures
among these molecules with analogous Hꢀbonded and covelentꢀ
bonded bentꢀcore structures.
complexes PIIIC5/AIIF*
,
PIIIC7/AIIF* and PIIIC9/AIIF*
displayed the widest BPI ranges of ∆TBPI = 10.8°C, 11.6°C and
12.0°C, at the correspondent molar ratios of Hꢀdonor AIIF*
=
70 mol%, 60 mol% and 70 mol%, respectively. Therefore, the
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 5 of 10
Journal Name
RSC Advances
View ArticAle ROnTliInCeLE
DOI: 10.1039/C5RA26827C
(c) Effects of covalent-bonded bent-core mixture and H-
bonded bent-core complex. Regardless of the similar structure
as the Hꢀbonded bentꢀcore diad PIIIC9/AIIF* (1/1 mol/mol), the
(a)
150
140
130
120
110
100
90
BPI
N*
K
PIIIC5 / AIIF*
covalentꢀbonded bentꢀcore analogue PIIIC9AIIF* does not
possess any mesophase. Since both of the Hꢀbonded bentꢀcore
diad PIIIC9/AIIF* = 1:1 (mol/mol) and its covalentꢀbonded
bentꢀcore analogue PIIIC9AIIF* do not possess any BPs, the Hꢀ
bonded bentꢀcore complex PIIIC9/AIIF* with proper molar
ratios of overꢀsupplied Hꢀdonor AIIF* (55ꢀ80 mol%) having the
BPI should be compared with its analogous covalentꢀbonded
bentꢀcore mixture PIIIC9AIIF*/AIIF* (with >50 mol% of Hꢀ
donor AIIF*). As shown in Fig. 2d, the covalentꢀbonded bentꢀ
core analogue PIIIC9AIIF* was used to replace the Hꢀbonded
bentꢀcore diad PIIIC9/AIIF* = 1:1, so the molar ratios of Hꢀ
donor AIIF* in PIIIC9AIIF*/AIIF* = 0, 18.2, 33.3, 46.2, 57.1,
66.7, 75.0, 82.4, 88.9, 94.7 and 100 mol% are equivalent to the
molar ratios of Hꢀdonor AIIF* in PIIIC9/AIIF* = 55, 60, 65, 70,
75, 80, 85, 90, 95 and 100 mol%, respectively. Compared with
PIIIC9/AIIF* possessing the BPI phase at the molar ratios of
AIIF*=55ꢀ80 mol% shown in Fig. 2a, the covalentꢀbonded
bentꢀcore mixture PIIIC9AIIF*/AIIF* only induced the BPIII
phase at molar ratios of AIIF* = 75.0 to 82.4 mol% in Fig. 2d.
Thus, the covalentꢀbonded bentꢀcore analogue PIIIC9AIIF*
(without any mesophase) might play an important role of a
biaxial component in the covalentꢀbonded bentꢀcore mixture
PIIIC9AIIF*/AIIF* to induce the BPIII phase. Due to the
existence of the chiral nematic phase for the LC host of the Hꢀ
bonded bentꢀcore diad (PIIIC9/AIIF* = 1:1), the Hꢀbonded bentꢀ
core complex PIIIC9/AIIF* possessed the widest blue phase
(i.e., ∆TBPI = 12.0°C) at the molar ratio of AIIF* = 70 mol%.
Therefore, both Hꢀbonded bentꢀcore diad PIIIC9/AIIF* = 1:1
and its covalentꢀbonded bentꢀcore analogue PIIIC9AIIF* have
different effects on their LC mixtures containing proper molar
ratios of overꢀsupplied Hꢀdonor AIIF* to favor various blue
phases, i.e., BPI and BPIII, respectively. Moreover, the bentꢀ
core molecules with wider chiral nematic phase (by introducing
Hꢀbonds) were also easier to stabilize and induce the BPI in the
Hꢀbonded bentꢀcore complexes.
80
70
60
50
40
50 55 60 65 70 75 80 85 90 95 100
AIIF* (mol%)
(b)
150
140
130
120
110
100
90
PIIIC7 / AIIF*
BPI
N*
K
80
70
60
50
40
50 55 60 65 70 75 80 85 90 95 100
AIIF* (mol%)
(c)
150
140
130
120
110
100
90
BPI
N*
PIIIC9 / AIIF*
K
80
70
60
50
40
50 55 60 65 70 75 80 85 90 95 100
AIIF* (mol%)
(d)
150
140
130
120
110
100
90
BPIII
N*
K
(iii) Effects of fluoro group and chiral center of H-donors on
H-bonded bent-core complexes. As shown in Fig. 3, two more
hybrid Hꢀbonded complexes PIIIC9/(AIIF*+AIIF) and
PIIIC9AIIF* / AIIF*
PIIIC9/(AIIF*+AII*) with dual Hꢀdonors (where
T = PIIIC9; D =
AIIF* AIIF and AII* are chiral/fluoro, achiral/fluoro and
,
80
chiral/nonꢀfluoro Hꢀdonors, respectively) were prepared to
compare the effects of the chiral center and fluoro group of Hꢀ
donors on Hꢀbonded bentꢀcore complexes in contrast to Hꢀ
bonded bentꢀcore complex PIIIC9/AIIF* at AIIF* = 70 mol%
(with the widest BPI range of ∆TBPI = 12.0°C). Hence, the total
molar ratio of dual Hꢀdonors (AIIF*+AIIF) and (AIIF*+AII*) in
hybrid Hꢀbonded complexes PIIIC9/(AIIF*+AIIF) and
PIIIC9/(AIIF*+AII*) was fixed at 70 mol% (similar to the
controlling sample with the widest BPI range). Regarding the
contribution of the chiral center of Hꢀdonor in hybrid Hꢀbonded
complex PIIIC9/(AIIF*+AIIF) in Fig. 3a, the BPI ranges were
gradually reduced by increasing the molar ratio of AIIF in the
dual Hꢀdonors (AIIF*+AIIF). Finally, the concentration of
AIIF* (replaced with AIIF without the chiral center) was too
70
60
50
40
0
18.2 33.3 46.2 57.1 66.7 75.0 82.4 88.9 94.7 100
AIIF* (mol%)
Fig. 2 Binary phase diagrams of Hꢀbonded bentꢀcore complexes (a)
PIII 5/AIIF*, (b) PIII 7/AIIF*, (c) PIII 9/AIIF* and covalentꢀbonded
bentꢀcore mixture PIII 9AIIF*/AIIF* with different molar ratios of
AIIF*. The POM observations and DSC measurements were carried out
at a cooling rate of 0.5°C minꢀ1 (Table S1 and S2). I: isotropic phase;
BPI: blue phase I; N*: chiral nematic phase; K: crystalline phase.
C
C
C
C
BPI ranges (∆TBPI) of Hꢀbonded bentꢀcore complexes were
affected by the alkyl chain length of Hꢀaccepter, where the
longer alkyl chain length the wider BPI ranges (∆TBPI), i.e.,
PIIIC5/AIIF*
< PIIIC7/AIIF* < PIIIC9/AIIF*. The symmetrical
alkyl chain lengths on both Hꢀdonor and Hꢀacceptors played an
important role on the molar ratio ranges of Hꢀdonor with BPI,
but the BPI ranges in Hꢀbonded bentꢀcore complexes were
affected by the alkyl chain lengths of Hꢀaccepters.
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 5

RSC Advances
Page 6 of 10
ARTICLE
VJieowuArrtnicalelONnlainme e
DOI: 10.1039/C5RA26827C
(a)
(a)
140
I
130
120
110
100
90
BPI
30
40
50
N*
K
60
)
70
C
o
(
80
e
r
u
90
t
a
r
100
e
p
110
m
e
T
120
80
130
140
150
70
2800
2600
2400
2200
)
2000
1800
Wavenumber (cmꢀ1
60
(b)
0
10
20
30
40
50
60
70
80
90
AIIF (mol%) in D (AIIF + AIIF*)
(b)
140
130
120
110
100
90
30
40
50
I
60
)
70
C
o
BPI
(
80
e
r
u
90
t
a
r
e
100
p
110
m
e
120
130
140
150
T
2800
2600
2400
2200
)
2000
1800
N*
K
Wavenumber (cmꢀ1
Fig. 4 Temperature dependent FTIR spectra of Hꢀbonded (a) diad
PIIIC9/AIIF* = 1/1 mol/mol and (b) complex PIIIC9/AIIF* = 3/7
mol/mol.
80
70
60
more effective than that of the chiral center. Hence, the polar
fluoro group of AIIF* is more important than its chiral center to
0
10
20 30
40
50 60
AII*
70
80 90 100
AII* (mol%) in
D
(
+
AIIF*)
stabilize the BPI phase in PIIIC9/AIIF*
.
Fig. 3 Binary phase diagrams of hybrid Hꢀbonded complexes PIIIC9/D
= 30/70 mol/mol with different molar ratios of AIIF*, where (a)
AIIF AIIF*, (b) AII*+AIIF*. The POM observations and DSC
measurements were carried out at a cooling rate of 0.5°C minꢀ1 (Table As shown in Figs. 4(a) and 4(b), the characteristic peaks of Hꢀ
Characterization of H-bonded structures
D
=
+
D =
S3). I: isotropic phase; BPI: blue phase I; N*: chiral nematic phase; K:
crystalline phase.
bonds formed by carboxylic acid/pyridyl groups could be
observed with different extents at various temperatures in the
Hꢀbonded bentꢀcore diad PIIIC9/AIIF* (1/1 mol/mol) and
low to maintain the required chiral concentration in hybrid Hꢀ
bonded complexes PIIIC9/(AIIF*+AIIF) at AIIF* = 20 mol% (i.e.,
AIIF = 80 mol%) of the dual Hꢀdonor (AIIF*+AIIF), so it was not
sufficient to sustain the BPI. On the contrary, the contribution of
the fluoro group of Hꢀdonor in hybrid Hꢀbonded complex
PIIIC9/(AIIF*+AII*) of Fig. 3b was verified that the BPI ranges
were more dramatically reduced by increasing the molar ratio of
complex PIIIC9/AIIF* (3/7 mol/mol), respectively, where the
stability of Hꢀbonds in the bentꢀcore diad and complex can be
directly confirmed by the temperatureꢀdependent FTIR spectra.
During the formation of Hꢀbonds in complexation of AIIF* (Hꢀ
donor) with PIIIC9 (Hꢀacceptor), the OꢀH bands of pure AIIF*
(Hꢀdonor) centred at about 2560 and 2673 cmꢀ1 were shifted to
1927 cmꢀ1 and 2550 cmꢀ1, respectively, indicating strong Hꢀ
bonding formed between the pyridyl and carboxylic acid groups
AII* in the dual Hꢀdonors (AIIF*+AII*). At last, the concentration in the asymmetric heterodimers.70,71 Two Hꢀbonded
characteristic peaks centred at about 2550.2 and 1927.3 cmꢀ1
of AIIF* (replaced with AII* without the fluoro group) was too
low to maintain the polarity in hybrid Hꢀbonded complexes
showed minor changes at higher temperatures of 130°C and
150°C in Figs. 4(a) and 4(b), which suggests the gradual
PIIIC9/(AIIF*+AII*) at AIIF* = 60 mol% (i.e., AII* = 40 mol%)
disappearance of stable Hꢀbonds in diad and complex. On the
of the dual Hꢀdonor (AIIF*+AII*). The additional information of
the total replacement of AIIF* with AII* in the hybrid Hꢀbonded
complex PIIIC9/(AIIF*+AII*) to become PIIIC9/AII* is shown in
other hand, the stretching vibration of carboxylic acid group
C=O appeared at 1700 cmꢀ1 and the stretching vibration of ester
carbonyl group C=O appeared at 1726 cmꢀ1. In the Hꢀbonded
asymmetric diad of PIIIC9/AIIF* (1/1 mol/mol), a shoulder can
be observed in the main peak located at 1726 cmꢀ1. This
shoulder is the carbonyl group which is in a less associated
state than the pure AIIF* (Hꢀdonor) with a weaker stretching
vibration in carboxylic acid group C=O appeared at 1700 cmꢀ1.
Fig. S2. According to Figs. 3a and 3b, the disappearance of BPI
in both hybrid Hꢀbonded complexes PIIIC9/(AIIF*+AIIF) and
PIIIC9/(AIIF*+AII*) occurred at a higher molar replacement of
AIIF* with AIIF (80 mol% without the chiral center) than that
with AII* (40 mol% without the fluoro group), so the replacement
of the polar fluoro group in the dual Hꢀdonor to eliminate BPI is
72,73
This is attributed to a stretching vibration in carboxylic
acid group C=O at 1700 cmꢀ1 in the pure Hꢀdonor AIIF* which
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 7 of 10
Journal Name
RSC Advances
View ArticAle ROnTliInCeLE
DOI: 10.1039/C5RA26827C
shifts toward a higher wavenumber and overlaps with the band Fig. 6 shows the absorbance spectra obtained for the Hꢀbonded
of the ester carbonyl group at 1726 cmꢀ1 in the Hꢀbonded complex PIIIC9/AIIF* = 30/70 (mol) upon cooling (cooling rate
asymmetric diad of PIIIC9/AIIF* (1/1 mol/mol). These = 0.5 °C/min). In fact, the absorbance peaks of LC phases (i.e.,
consequences show that hydrogen bonds were formed between BPs and N*) in the Hꢀbonded bentꢀcore complex PIIIC9/AIIF*
AIIF* (Hꢀdonor) and PIIIC9 (Hꢀacceptor) as well as the other Hꢀ = 30/70 (mol) were reflected away by the special pitches of BPI
bonded complexes.
or chiral nematic phases. Importantly, no obvious absorbance
peaks in Hꢀbonded complex PIIIC9/AIIF* = 30/70 (mol) were
observed at higher temperature (115°C). However, a specific
absorbance peak ca. 480 nm of Hꢀbonded complex PIIIC9/AIIF*
= 30/70 (mol) appeared by decreasing temperatures to the range
of 114ꢀ103°C, which could be assigned to the Bragg diffraction
from the 110 plane of the cubic lattice in BPI.22 A platelet
texture of BPI was observed by POM over the same
temperature range at 108°C (see Fig. 5i). Moreover, a broader
absorbance peak around 570 nm (with another different pattern
from that of BPI) in Fig. 6 corresponds to the selective
diffraction of N*. The absorbance spectral changes were
reversible during different heating and cooling cycles.
Therefore, the BPI phase range of 114ꢀ103°C verified by the
absorbance spectral changes of PIIIC9/AIIF* was compatible
with that observed by the characterization of POM textures.
Optical and UV-Vis investigations
The mesophases of Hꢀbonded bentꢀcore diads and complexes
were characterized by the photoꢀimages of POM textures at
different temperatures, which are illustrated in Figs. 5(a)ꢀ5(c)
for PIIIC5/AIIF* at 50/50, 35/65 and 30/70 mol/mol,
respectively, Figs. 5(d)ꢀ5(f) for PIIIC7/AIIF* at 50/50, 40/60
and 35/65 mol/mol, respectively and Figs. 5(g)ꢀ5(i) for
PIIIC9/AIIF* at 50/50, 35/65 and 30/70 mol/mol, respectively.
The chiral nematic phase (N*) and blue phase I (PBI) were
confirmed by POM textures with fine stripes and colourful
platelets, respectively.
N*
N*
N*
(a)
(d)
(g)
(b)
(e)
(h)
BPI
BPI
BPI
(c)
(f)
(i)
BPI
BPI
BPI
Conclusions
We synthesized and prepared a series of Hꢀboned bentꢀcore LC
diads (T/D=1) and complexes (T/D<1) consisting of pyridyl
and benzoic acid derivatives as Hꢀaccepters
T and Hꢀdonors D,
respectively. The chiral nematic phase of Hꢀboned bentꢀcore
LC diads (T/D=1) was induced by introducing the Hꢀbonds on
the covalentꢀbonded bentꢀcore supramolecules, and the widest
chiral nematic phase range of Hꢀbonded bentꢀcore diad
PIIIC9/AIIF* =1:1 was obtained by introducing the Hꢀbond at
the center of the bentꢀcore supramolecule. Therefore, the longer
alkyl chain of Hꢀaccepter and lateral fluoro group of Hꢀdonor
would promote the chiral nematic phase ranges in Hꢀbonded
bentꢀcore diads. The Hꢀbonded bentꢀcore complex PIIIC9/AIIF*
(3/7 mol/mol) showed the widest range of BPI (i.e., ∆TBP
=
Fig. 5 POM textures of Hꢀbonded bentꢀcore diads and complexes for
PIIIC5/AIIF* with (a) 50/50 mol at 60°C, (b) 35/65 mol at 80°C, (c)
30/70 mol at 85°C; PIIIC7/AIIF* with (d) 50/50 mol at 75°C, (e) 40/60
mol at 94°C, (f) 35/65 mol at 102°C; PIIIC9/AIIF* with (g) 50/50 mol at
75°C, (h) 35/65 mol at 100°C, (i) 30/70 mol at 108°C. (Scale bar: 40
ꢁm. White arrows are the directions of polarizers and analyzers)
12.0°C) upon cooling. As a result, the longer alkyl chain length
of Hꢀaccepter and lateral fluoro group of Hꢀdonor could induce
and stabilize the blue phase (BPI) range at special molar ratios
of Hꢀdonor AIIF* (55ꢀ80 mol%) in Hꢀbonded bentꢀcore
complexes. Interestingly, the analogous covalentꢀbonded bentꢀ
core mixture PIIIC9AIIF*/AIIF* only induced the BPIII phase at
molar ratios of AIIF* = 75.0 to 82.4 mol%, rather than the BPI
phase induced by the similar Hꢀbonded bentꢀcore complex
PIIIC9/AIIF* (3/7 mol/mol). Accordingly, we could summarize
that the introduction of Hꢀbonds in the bentꢀcore center of the
supramolecular complexes effectively induce and stabilize the
BP phase. Moreover, not only the molar ratio of the chiral
dopant affects the BPI range, but also the fluoro group of the
proton donor directly affect the BPI formation of Hꢀbonded
bentꢀcore complexes.
68oC
85oC
102oC
103oC
114oC
450
115oC
550
Cooling
750 800
Acknowledgements
The financial supports of this project are provided by the
Ministry of Science and Technology (MOST) in Taiwan
through MOST103ꢀ2113ꢀMꢀ009ꢀ018ꢀMY3 and MOST103ꢀ
2221ꢀEꢀ009ꢀ215ꢀMY3.
350
400
500
600
650
700
Wavelength (nm)
Fig. 6 Absorbance spectral change versus temperature for Hꢀbonded
complex PIIIC9/AIIF* (30/70 mol), including the phase ranges of BPI
and N*.
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 7

RSC Advances
Page 8 of 10
VJieowuArrtnicalelONnlainme e
ARTICLE
DOI: 10.1039/C5RA26827C
Notes and references
31 L. Wang, W. He, X. Xiao, Q. Yang, B. Yang, P. Li, H. Yang, J.
Mater. Chem., 2012, 22, 2383ꢀ2386.
1
2
3
4
I. Fischer, N. Shah, A. Rosch, Phys. Rev. B 2008, 77, 024415.
A. Yoshizawa, RSC Adv., 2013, , 25475ꢀ25497.
3
32 K. W. Park, M. J. Gim, S. Kim, S. T. Hur, S. W. Choi, ACS Appl.
W. Kossel, V. Loeck, H. Z. Voges, A: Hadrons Nucl., 1935, 94, 139.
R. J. Miller, H. F. Gleeson, J. E. Lydon, Phys. Rev. Lett., 1996, 77
857ꢀ860.
Mater. Interfaces, 2013,
33 M. Grunert, R. A. Howie, A. Kaeding, C. T. Imrie, J. Mater. Chem.,
1997, , 211ꢀ214.
5, 8025ꢀ8029.
,
7
5
6
R. M. Hornreich, S. Shtrikman, Phys. Rev. A, 1981, 24, 635ꢀ638.
34 J. Wang, Y. Shi, K. Yang, J. Wei, J. Guo, RSC Adv., 2015, 5, 67357ꢀ
L. Longa, D. Monselesan, H. R. Trebin, Liq. Cryst., 1989,
5, 889ꢀ
67364.
898.
35 W. L. He, G. H. Pan, Z. Yang, D. Y. Zhao, G. G. Niu, W. Huang, X.
T. Yuan, J. B. Guo, H. Cao, H. Yang, Adv. Mater., 2009, 21, 2050ꢀ
2053.
7
8
9
P. Pieranski, R. B. Massin, P. E. Cladis, Phys. Rev. A, 1985, 31,
3912ꢀ3923.
O. Henrich, K. Stratford, M. E. Cates, D. Marenduzzo, Phys. Rev. 36 E. Grelet, B. Pansu, M. H. Li, H. T. Nguyen, Phys. Rev. Lett., 2001,
Lett., 2011, 106, No. 107801. 86, 3791ꢀ3794
A. Yoshizawa, M. Kamiyama, T. Hirose, Appl. Phys. Express, 2011, 37 H. J. Coles, M. N. Pivnenko, Nature, 2005, 436, 997ꢀ1000.
4
, No. 101701.
38 J. Rokunohe, A. Yoshizawa, J. Mater. Chem., 2005, 15, 275ꢀ279.
39 A. Yoshizawa, Y. Kogawa, K. Kobayashi, Y. Takanishi, J.
Yamamoto, J. Mater. Chem., 2009, 19, 5759ꢀ5764.
10 Y. F. Lan, C. Y. Tsai, J. K. Lu, N. Sugiura, Opt. Express, 2013, 21
5035ꢀ5040.
,
11 S. Meiboom, M. Sammon, Phys. Rev. Lett., 1980, 44, 882ꢀ885.
12 M. Sato, A. Yoshizawa, Adv. Mater., 2007, 19, 4145ꢀ4148.
13 L. Rao, Z. Ge, S. T. Wu, Opt. Express, 2010, 18, 3143ꢀ3148.
40 B. Y. Zhang, F. B. Meng, Y. H. Cong, Opt. Express, 2007, 15,
10175ꢀ10181.
41 A. Hauser, M. Thieme, A. Saupe, G. Heppke, D. Kruerke, J. Mater.
Chem., 1997, , 2223ꢀ2229.
14 J. Yan, S. T. Wu, K. L. Cheng, J. W. Shiu, Appl. Phys. Lett., 2013,
102, No. 081102.
7
42 O. Jin, D. Fu, J. Wei, H. Yang, J. Guo, RSC Adv., 2014, 4, 28597ꢀ
15 W. Cao, A. Munoz, P. P. Muhoray, B. Taheri, Nat. Mater., 2002,
1,
28600.
111ꢀ113.
43 H. Y. Liu, C. T. Wang, C. Y. Hsu, T. H. Lin, J. H. Liu, Appl. Phys.
Lett., 2010, 96, No. 121103.
16 K. Higashiguchi, K. Yasui, H. kikuchi, J. Am. Chem. Soc., 2008, 130
,
6326ꢀ6327.
44 A. Yoshizawa, Y. Kogawa, K. Kobayashi, Y. Takanishi, J.
Yamamodo, J. Mater. Chem., 2009, 19, 5759ꢀ5764.
17 K. Kim, S. T. Hur, S. Kim, S. Y. Jo, B. R. Lee, M. H. Song, S. W.
Choi, J. Mater. Chem. C, 2015, , 5383ꢀ5388.
3
45 I. H. Chiang, C. J. Long, H. C. Lin, W. T. Chuang, J. J. Lee, H. C.
18 C. Y. Huang, J. J. Stott, R. G. Petschek, Phys. Rev. Lett., 1998, 80
,
Lin, ACS Appl. Mater. Interfaces, 2014,
46 C. L. Wei, T. C. Chen, P. Raghunath, M. C. Lin, H. C. Lin, RSC
Adv., 2015, , 4615ꢀ4622.
6, 228ꢀ235.
5603ꢀ5606.
19 H. Y. Liu, C. T. Wang, C. Y. Hsu, T. H. Lin, J. H. Liu, Appl. Phys.
Lett., 2010, 96, No. 121103.
5
47 P. L. Madhuri, S. K. Prasad, G. G. Nair, RSC Adv., 2014, 4, 3121ꢀ
20 F. Castles, F. V. Day, S. M. Morris, D. H. Ko, D. J. Gardiner, M. M.
3130.
Qasim, S. Noheen, P. J. W. Hands, S. S. Choi, R. H. Friend, H. J. 48 T. T. Nguyen, S. Albert, T. L. A. Nguyen, R. Deschenaux, RSC Adv.,
Coles, Nat. Mater., 2012, 11, 599ꢀ603. 2015, , 27224ꢀ27228.
21 P. P. Crooker in Chirality in Liquid Crystals (Eds.: H. S. Kitzerow, 49 I. H. Chiang, W. T. Chuang, C. L. Lu, M. T. Lee, H. C. Lin, Chem.
C. Bahr), Springer, 2001, PP. 186ꢀ222. Mater., 2015, 27, 4525ꢀ4537.
22 H. Kikuchi, M. Yokota, Y. Hisakado, H. Yang, T. Kajiyama, Nat. 50 M. Caricato, A. K. Sharma, C. Coluccini, D. Pasini, Nanoscale, 2014,
Mater., 2002, , 64ꢀ68. , 7165ꢀ7174.
23 L. Wang, W. He, Q. Wang, M. Yu, X. Xiao, Y. Zheng, M. Ellahi, D. 51 M. Caricato, A. Delforge, D. Bonifazi, D. Dondi, A. Mazzanti, D.
5
1
6
Zhao, H. Yang, L. Guo, J. Mater. Chem. C, 2013,
24 J. Yan, S. T. Wu, Opt. Mater. Express, 2011, , 1527ꢀ1535.
25 F. Peng, Y. Chen, J. Yuan, H. Chen, S. T. Wu, Y. Haseba, J. Mater.
Chem. C, 2014, , 3597ꢀ3601.
26 H. Yoshida, Y. Tanaka, K. Kawamoto, H. Kubo, T. Tsuda, A. Fujii, 54 C. Tschierske, D. J. Photinos, J. Mater. Chem., 2010, 20, 4263ꢀ4294.
1
, 6526ꢀ6531.
Pasini, Org. Biomol. Chem., 2015, 13, 3593ꢀ3601.
1
52 C. Coluccini, M. Caricatio, E. Cariati, S. Righetto, A. Forni, D.
Pasini, RSC Adv., 2015,
5, 21495ꢀ21503.
2
53 G. R. Luckhurst, Angew. Chem. Int. Ed. 2005, 44, 2834ꢀ2836.
S. Kuwabata, H. Kikuchi, M. Ozaki, Appl. Phys. Express, 2009,
2
,
55 A. Yoshizawa, M. Sato, J. Rokunohe, J. Mater. Chem., 2005, 15
,
No. 121501.
3285ꢀ3290.
27 E. karatairi, B. Rozic, Z. Kutnjak, V. Tzitzios, G. Nounesis, G. 56 M. Sato, A. Yoshizawa, Adv. Mater., 2007, 19, 4145ꢀ4148.
Cordoyiannis, J. Thoen, C. Glorieux, S. Kralj, Phys. Rev. E, 2010, 81
,
57 M. Tanaka, A. Yoshizawa, J. Mater. Chem. C, 2013, 1, 315ꢀ320.
No. 041703.
58 R. Nomura, J. Tabei, T. Masuda, J. Am. Chem. Soc., 2001, 123
,
28 L. A. Madsen, T. J. Dingemans, M. Nakata, E. T. Samulski, Phys.
Rev. Lett., 2004, 92, No. 145505.
8430ꢀ8431.
59 M. V. Sigalov, B. A. Shainyan, N. N. Chipanina, L. P. Oznobikhina,
J. Phys. Chem. A, 2013, 117, 11346ꢀ11356.
29 H. Iwamochi, T. Hirose, Y. Kogawa, A. Yoshizawa, Chem. Lett.,
2010, 39, 170ꢀ171.
60 U. Kumar, T. Kato, J. M. J. Frechet, J. Am. Chem. Soc., 1992, 114
,
30 M. Lee, S. T. Hur, H. Higuchi, K. Song, S. W. Choi, H. Kikuchi, J.
Mater. Chem., 2010, 20, 5813ꢀ5816.
6630ꢀ6639.
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 9 of 10
Journal Name
RSC Advances
View ArticAle ROnTliInCeLE
DOI: 10.1039/C5RA26827C
61 T. Kato, J. M. J. Frechet, P. G. Wilson, T. Saito, T. Uryu, A.
Fujishima, C. Jin, F. Kaneuchi, Chem. Mater., 1993, , 1094ꢀ1100.
62 T. R. Shattock, K. K. Arora, P. Vishweshwar, M. J. Zaworotko,
Cryst. Growth Des., 2008, , 4533ꢀ4545.
5
8
63 Y. Zhang, Y. Guan, S. Yang, J. Xu, C. C. Han, Adv. Mater., 2003, 15
,
832ꢀ835.
64 Y. Li, Y. Cong, H. Chu, B. Zhang, J. Mater. Chem. C, 2014, 2, 1783ꢀ
1790.
65 W. H. Binder, S. Bernstorff, C. Kluger, L. Petraru, M. J. Kunz, Adv.
Mater., 2005, 17, 2824ꢀ2828.
66 J. Huo, Y. Shi, X. Han, O. Jin, J. Wei, H. Yang, J. Mater. Chem. C
2013, , 947ꢀ957.
,
1
67 W. L. He, G. H. Pan, Z. Yang, D. Y. Zhao, G. G. Niu, W. Huang, X.
T. Yuan, J. B. Guo, H. Cao, H. Yang, Adv. Mater., 2009, 21, 2050ꢀ
2053.
68 L. Y. Wang, I. H. Chiang, P. J. Yang, W. S. Li, I. T. Chao, H. C. Lin,
J. Phys. Chem. B, 2009, 113, 14648ꢀ14660.
69 L. Y. Wang, H. Y. Tsai, H. C. Lin, Macromolecules, 2010, 43, 1277.
70 C. Osuji, C. Y. Chao, I. Bita, C. K. Ober and E. L. Thomas, Adv.
Funct. Mater., 2002, 12, 753–758.
71 B. Basu, RSC Adv., 2014, 4, 13854ꢀ13881.
72 L. Y. Wang, S. Y. Tsa and H. C. Lin, Macromolecules, 2010, 43
1277–1288.
,
73 P. J. Yang, L. Y. Wang, C. Y. Tang and H. C. Lin, J. Polym. Sci.,
Part A: Polym. Chem., 2010, 48, 764–774.
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 9

RSC Advances
Page 10 of 10
VJieowuArrtnicalelONnlainme e
ARTICLE
DOI: 10.1039/C5RA26827C
For Table of Contents/Abstract Graphic Use Only
Hydrogen-bonded bent-core blue phase liquid crystal complexes containing various molar ratios of
proton acceptors and donors
ChunꢀChieh Han, YuꢀChaing Chou and HongꢀCheu Lin*
Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan
Table of Contents (TOC)/ABSTRACT Graphic
O
O
F
N
O
O
O
HO
O
OH
O
O
O
O
O
O
O
O
OH HO
+
O
O
F
PIIIC9/AIIF* = 3/7 mol/mol
Iso 114.5 [0.25] BPI 102.5 N* 67.3 [1.60] K (BPI = 12°C
)
In BPLC complexes, the molar ratios, alkyl chain lengths, the lateral fluoroꢀsubstitution and the chiral center of Hꢀ
bonded bentꢀcore supramolecules would affect their temperature ranges of BPs. Hꢀbonded bentꢀcore complex
PIIIC9/AIIF* (3/7 mol/mol) displayed the widest BPI ranges of ∆TBPI = 12.0°C at the correspondent Hꢀaccepter
T =
PIIIC9 (with the longest alkyl chain length
C9) and Hꢀdonor D = AIIF* (with a lateral fluoroꢀsubstitution and a chiral
center).
10 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012