Formation of columnar and cubic mesophases by calamitic molecules: Novel amphotropic biphenyl derivatives

Article abstract of DOI:10.1021/jp981158x

Novel amphiphilic 4,4a?2-disubstituted biphenyl derivatives incorporating a hydrophilic 5,6-dihydroxy-3-oxahexyloxy group and a lipophilic chain have been synthesized by Pd-catalyzed cross-coupling reactions of phenyl boronic acids with 4-(5,6-dihydroxy-3-oxahexyloxy)bromobenzenes. The thermotropic and lyotropic mesomorphic behavior of these compounds were investigated by polarizing microscopy, by differential scanning calorimetry and by means of X-ray diffraction. Thereby the influence of the length of the alkyl chain, the type of connecting unit between alkyl-chain and the rigid core (O vs CH₂), and the influence of lateral substituents and of the molecular chirality on the mesomorphic properties were investigated. All compounds have smectic A-phases as the high-temperature mesophases. Additionally, columnar phases were found for the long chain 4a?2-alkoxy-4-(5,6-dihydroxy-3-oxahexyloxy)biphenyls 2c-f without lateral substituent and for the 4-(5,6-dihydroxy-3-oxahexyloxy)-4a?2-dodecyloxy-3a?2-methylbiphenyl 10. All other laterally substituted biphenyl derivatives 9 and 11-15 and the 4a?2-alkyl substituted compound 8 display only smectic phases. The influence of protic solvents (formamide and ethylene glycol) on the liquid crystalline properties was studied. The columnar mesophases and S_C-phases are destabilized by addition of protic solvents whereas the S_A-phases are stabilized. Furthermore, binary mixtures of the amphiphilic biphenyl derivatives with each other have been investigated. Complete miscibility was found for the S_A-phases and the columnar phases of the compounds 2c-f. However the columnar phases of the nonsubstituted compounds 2c-f and the 3a?2-methyl substituted derivative 10 do not have an uninterrupted miscibility. Cubic phases (Pn3m or Pn3) and additional columnar phases were induced in the contact regions. Thus, the same diversity of different kinds of mesophases as in lyotropic systems and in the thermotropic phase sequence of polycatenar compounds is found. It is proposed that the cubic and columnar mesophases of these rodlike molecules result from the collapse of the smectic layer structures into ribbons.

Full text of DOI:10.1021/jp981158x

J. Phys. Chem. B 1998, 102, 5261-5273
5261
Formation of Columnar and Cubic Mesophases by Calamitic Molecules: Novel
Amphotropic Biphenyl Derivatives
Niels Lindner,† Marius Ko1lbel,† Christiane Sauer,‡ Siegmar Diele,‡ Jani Jokiranta,†,§ and
Carsten Tschierske*,†
Institute of Organic Chemistry, Martin-Luther-UniVersity Halle, D-06120 Halle,
Kurt-Mothes-Strasse 2, Germany, and Institute of Physical Chemistry, Martin-Luther-UniVersity Halle,
D-06118 Halle, Mu¨hlpforte 1, Germany
ReceiVed: February 16, 1998; In Final Form: April 21, 1998
Novel amphiphilic 4,4′-disubstituted biphenyl derivatives incorporating a hydrophilic 5,6-dihydroxy-3-
oxahexyloxy group and a lipophilic chain have been synthesized by Pd-catalyzed cross-coupling reactions of
phenyl boronic acids with 4-(5,6-dihydroxy-3-oxahexyloxy)bromobenzenes. The thermotropic and lyotropic
mesomorphic behavior of these compounds were investigated by polarizing microscopy, by differential scanning
calorimetry, and by means of X-ray diffraction. Thereby the influence of the length of the alkyl chain, the
type of connecting unit between alkyl-chain and the rigid core (O vs CH2), and the influence of lateral
substituents and of the molecular chirality on the mesomorphic properties were investigated. All compounds
have smectic A-phases as the high-temperature mesophases. Additionally, columnar phases were found for
the long chain 4′-alkoxy-4-(5,6-dihydroxy-3-oxahexyloxy)biphenyls 2c-f without lateral substituent and for
the 4-(5,6-dihydroxy-3-oxahexyloxy)-4′-dodecyloxy-3′-methylbiphenyl 10. All other laterally substituted
biphenyl derivatives 9 and 11-15 and the 4′-alkyl substituted compound 8 display only smectic phases. The
influence of protic solvents (formamide and ethylene glycol) on the liquid crystalline properties was studied.
The columnar mesophases and SC-phases are destabilized by addition of protic solvents whereas the SA-
phases are stabilized. Furthermore, binary mixtures of the amphiphilic biphenyl derivatives with each other
have been investigated. Complete miscibility was found for the SA-phases and the columnar phases of the
compounds 2c-f. However the columnar phases of the nonsubstituted compounds 2c-f and the 3′-methyl
substituted derivative 10 do not have an uninterrupted miscibility. Cubic phases (Pn3m or Pn3) and additional
columnar phases were induced in the contact regions. Thus, the same diversity of different kinds of mesophases
as in lyotropic systems and in the thermotropic phase sequence of polycatenar compounds is found. It is
proposed that the cubic and columnar mesophases of these rodlike molecules result from the collapse of the
smectic layer structures into ribbons.
Introduction
In a project aimed at the synthesis of novel amphotropic liquid
crystals we have combined rigid biphenyl and p-terphenyl rods
The liquid crystalline state which combines order and mobility
on a molecular level is of great interest for material science as
well as for life science. It can be found in different classes of
compounds such as anisometric (rod-shaped or disklike) mol-
ecules, amphiphilic molecules and in block copolymers, in pure
materials (thermotropic phases), and in mixed systems with
appropriate solvents (lyotropic phases). The mobility is caused
by the thermal motion of the molecules whereas the order is
provided by a combination of molecular anisometry, attractive
forces and micro segregation. The combination of micro
segregation1 and molecular anisometry could lead to interesting
new materials with unusual properties. Thus, rod-coil mol-
ecules2 and rod-coil block copolymers3 have been synthesized.
Furthermore, in low molecular weight molecules rodlike and
disklike rigid units have been combined with perfluorinated
segments,4 oligosiloxane units,5 and with hydrophilic groups.6
with flexible and lipophilic alkyl chains and with flexible, but
polar oligooxyethylene chains terminated with hydroxy groups.7,8
The hydroxy groups provide attractive intermolecular interac-
tions9 which enhance the segregation tendency of the polyether
chains. These molecules can be regarded as low molecular
weight block molecules composed of three distinct units
incompatible with each other (polyphilic molecules).4f Colum-
nar mesophases have for example been found for 4,4′′-
dialkoxyterphenylderivatives with laterally attached polyether
chains.7,8b The fixation of a polyether chain in a terminal
position at a rigid core8,10 however can lead to a pronounced
layer like organization.8a
More recently we have synthesized the amphiphilic biphenyl
derivatives 1-4 carrying an alkyl chain at one end and a
polyether chains at the other terminus.8 Those compounds,
incorporating an 1,2-diol group and additionally at least one
oxyethylene unit (comp. 2e-4) display two mesophases (see
Figure 1). In the cases of compounds 3 and 4 with long
polyether chains an SA/SC-dimorphism was observed.8 In
contrast to 3 and 4 the low-temperature phase of compound 2e
displays an optical texture which is not typical for an SC-phase.
* To whom correspondence should be addressed: Institute of Organic
Chemistry, University Halle, Kurt-Mothes-Str. 2, D-06120 Halle, Germany;
Fax, +49(0)345 55 27030; e-mail, coqfx@mlucom6.urz.uni-halle.de.
† Institute of Organic Chemistry.
‡ Institute of Physical Chemistry.
§ Permanent address: Faculty of Chemical Engineering, Lappeenranta
University of Technology, Lappeenranta, Finland.
S1089-5647(98)01158-4 CCC: $15.00 © 1998 American Chemical Society
Published on Web 06/17/1998

5262 J. Phys. Chem. B, Vol. 102, No. 27, 1998
Lindner et al.
SCHEME 1: Synthesis of the Compounds 2a, 2c-f,
8-13, and 15.
Figure 1. Comparison of the phase transition temperatures of the
4-dodecyloxybiphenyl derivatives 1, 2e, 3, and 4 with different
hydrophilic groups (values taken from ref. 8).
Furthermore, the X-ray pattern of a nonoriented sample in the
unknown mesophase is characterized by several sharp reflections
in the small angle region. In the wide angle region a diffuse
scattering suggests the liquid like behavior concerning the lateral
molecular distances. Therefore this unknown phase could not
be a smectic low-temperature phase. Because the positions of
the reflections in the small angle region exclude a hexagonal
columnar arrangement, it was assumed, that this phase can be
a rectangular or an oblique columnar phase.8
separate paper, 1-(5,6-dihydroxy-3-oxahexyloxy)-4-iodo-2-
methylbenzene (7c) was used for the synthesis of compound
14. The optically active diol (S)-7a was obtained by enantio-
selective Sharpless dihydroxylation13 using â-AD-Mix in 64%
enantiomeric excess (determined by 1H and 19F NMR analysis
of the diastereomeric Mosher’s ester14). The final products were
purified by chromatography, followed by recrystallization from
petroleum ether/ethyl acetate/chloroform mixtures.
To clarify the reason for the unusual phase behavior of this
compound, novel amphiphilic biphenyl derivatives were syn-
thesized and the influence of various structural variations on
their mesomorphic behavior was investigated. Thereby the
length of the alkyl chain, the type of connecting unit between
alkyl-chain and rigid core (O vs CH2), the influence of lateral
substituents in two different positions, and the influence of
optical activity on the thermotropic and lyotropic mesomorphic
behavior, as well as binary mixtures of these compounds, were
investigated.
3. Results
3.1. Thermotropic Properties of the Pure Compounds.
Influence of the Length of the Terminal Alkoxy Chain. The
thermotropic phase transition temperatures of the alkoxy
substituted compounds 2 in dependence on the length of the
alkoxy chains are given in Table 1. All investigated compounds
2 exhibit an enantiotropic polymorphism with a smectic A-phase
as high-temperature mesophase.
Compounds 2a-2c which have the shortest alkyl chains
display a smectic C-phase below the SA-phase. By cooling the
SC-phase of 2c an additional phase transition to another
mesophase can be found; the typical SC-schlieren texture passes
over in a fanlike texture, which is known for columnar
mesophases (Figure 2a). The same texture is found on cooling
the homeotropically aligned SA-phase of 2d, but no additional
SC-phase appears. The optical textures observed for the low-
temperature mesophases of the other homologues 2e and f
(Figure 2b) differ from those of 2c and d.
The DSC heating traces of the compounds 2 are shown in
Figure 3. It can be seen, that all compounds have at least two
different crystalline phases cr1 and cr2 beside the liquid
crystalline phases. Remarkably the transition from the meso-
morphic state to cr2 cannot be supercooled as obvious from the
heating and cooling scan of compound 2e shown in Figure 4.
To obtain information about the structure of the mesophases
X-ray measurements were done. In the SA-phase of all
homologue the diffraction pattern exhibit the characteristic
feature of smectic phases without order in the layers. The layer
reflection and its second order and a diffuse halo at about 10°
2. Synthesis
The desired compounds were prepared by Suzuki cross-
coupling11 of the 4-(5,6-dihydroxy-3-oxahexyloxy)bromoben-
zenes 7 with appropriate phenyl boronic acids 6 (see Scheme
1). The racemic 4-(5,6-dihydroxy-3-oxahexyloxy)bromo-
benzenes 7 were obtained by OsO4-catalzed dihydroxylation12
of the corresponding allyl ethers 5. Compound 2b was
synthesized using another approach which will be reported in a

Novel Amphotropic Biphenyl Derivatives
J. Phys. Chem. B, Vol. 102, No. 27, 1998 5263
TABLE 1: Phase Transition Temperatures (°C) and Associated Enthalpy Values (kJ/mol, Lower Lines in Brackets) of the Pure
4-Alkoxy-4′-(5,6-dihydroxy-3-oxapentyl)biphenyles 2a-f and Clearing Temperatures of the SA-Phases of the Solvent Saturated
Samples
Tcl ethylene
Tcl formamide
compd
n
cr1
cr2
146
(18.1)
146
(19.5)
143
(19.4)
143
(17.8)
142
(17.6)
143
(17.9)
139
Col
146
SC
SA-is
glycol saturated
saturated
2a
8
115/121a
(8.0/4.3)
118
(14.3)
120
(14.9)
128
(23.3)
127
(19.7)
128
(20.1)
130
153
(0.7)
150
169
(12.7)
171
(12.3)
171
(11.9)
171
(11.8)
170
(10.8)
171
(10.4)
171
125
128
130
132
135
134
146
152
161
173
178
183
184
189
2b
9
10
11
12
12
14
(0.7)
147
2c
(0.9)b
2d
147
(0.9)
147
(0.9)
149
(1.0)
147
2ec
(S)-2e
2f
(23.6)
(17.7)
(0.7)
(8.7)
a Different crystalline modifications. b Not resolved. c Values obtained from a new sample. They slightly differ (1-2 K) from the values given
in ref 8.
Figure 3. DSC-heating curves (10 K min-1) of the compounds 2.
is nearly a linear function of n, but the increase of the d-value
with n is essential smaller than expected for a bilayer structure
(0.11 nm/CH2-group instead of 0.25 nm/CH2-group). It sup-
poses that the alkyl chains are strongly disordered or interdigi-
tated.
Upon cooling, the SA-phase of 2c-f into the unknown phase
the reflections of the SA-phase are maintained, but additional
sharp scatterings of very low intensity at small angles appear,
which, however, could not be indexed assuming a hexagonal
or rectangular cell. Therefore a two-dimensional oblique lattice
is assumed. The evaluation of the pattern with this assumption
leads to a good agreement of the observed and calculated
reflections and is given in Table 2 for compound 2f. The lattice
parameters of the columnar mesophase of this compound amount
a ) 6.23 nm; b ) 5.68 nm; γ ) 71.5°. Here the b-parameter
corresponds approximately to the maximal layer thickness of
the SA-phase (d ) 5.8 nm).
Figure 2. Optical photomicrographs (crossed polarizers) of the textures
of the thermotropic columnar phase of compound 2c at (a) 145 °C and
2f at (b) 145 °C.
appear. The observed smectic layer thickness is significantly
larger than the length of the molecules (d/L ≈ 1.7) proving the
existence of bimolecular smectic layers. In Figure 5, the
d-values for the SA-phases are plotted as a function of the
number n of carbon atoms in the alkyl chains. The layer spacing
Comparing the pattern of the homologues 2c-f in the
columnar phase, it is obvious that the number of the detected
reflections in the small angle region depends on the length of

5264 J. Phys. Chem. B, Vol. 102, No. 27, 1998
Lindner et al.
fan shape texture, which is known for ordered tilted smectic
phases. In agreement with the observed texture, the X-ray
pattern of this low-temperature phase shows only one outer sharp
scattering beside the inner layer reflections (up to the sixth order)
pointing to a smectic F or smectic I phase. A definite distinguish
between SF and SI can be given only on the basis of oriented
samples which have not been obtained.
Molecular Chirality. The transition temperatures and the
textures of the mesophases of the racemic compound 2e and
its enantiomerically enriched sample (S)-2e are nearly identical
(Table 1). It seems that, in this class of compounds, there is
no significant influence of molecular chirality on the mesomor-
phic properties. Therefore no further investigations have been
carried out.
Figure 4. DSC heating and cooling trace (10 K min-1) of compound
2e.
Lateral Substituents. Lateral substituents (F, CH3, and OCH3)
were placed either in ortho-position to the polar headgroup (3-
substituted derivatives 13-15) or in ortho-position to the
terminal alkyl chain (3′-substituted compounds 9-11). Com-
pound 12 contains two lateral substituents. All compounds with
a lateral group neighboring the polar group have only SA-phases.
Exclusively SA-phases were also found if polar groups (F or
MeO) are placed close to the alkyl chain.
A broad region of a columnar phase is observed for the 3′-
methyl substituted compound 10 between 80 and 102 °C.
However, the texture of this mesophase (Figure 6) differs
significantly from those of the columnar phases of the com-
pounds 2c-f. Likewise the X-ray pattern shows differences
from those of the columnar phases of compounds 2c-f. Again,
several sharp reflections were detected in the small angle region
(Figure 7), but the ratio of the Bragg angles of the reflections
is different. In the wide angle region an amorphous scattering
at about 10° was found. Also miscibility investigations point
to another type of columnar phase (see below). Further X-ray
studies at oriented samples are under way, to elucidate the
structure.
Figure 5. Layer spacing (d) of the SA-phases of compounds 2c-f as
a function of the number of carbon atoms in the alkyl chains as obtained
on cooling after the transition from the isotropic liquid (b) and before
the phase transition (2).
TABLE 2: Observed Reflections in the Columnar Phase of
Compound 2f
3.2. Lyotropic Properties in the Presence of Protic
Solvents. Because the compounds under consideration represent
amphiphilic molecules, we have studied their behavior in the
presence of protic solvents. Since the transition temperatures
of the pure compounds exceed 100 °C, we did not use water,
but other protic solvents with elevated boiling points were used
for these investigations. Ethylene glycol and formamide were
chosen. The transition temperatures of the solvent saturated
samples of the compounds 2 and 9-15 are included in Tables
1 and 3. Generally the solvent saturated samples display
decreased melting temperatures of the crystalline phases and
the smectic A-phase is the only mesophase observed. The
influence of these two solvents on the clearing temperatures is
different. With exception of the short chain derivatives 2a and
b, the SA-phases are stabilized on addition of formamide,
whereas on addition of ethylene glycol the clearing temperatures
of all compounds are depressed.
θ
exp(deg)
θ
cal(deg)
hk
0.746
0.818
0.916
1.455
1.502
1.575
10
01
11
21; 2h1h
20; 2h0
12; 1h2h
1.457
1.492
1.569
the alkyl chains. Whereas in the diffraction pattern of compound
2f six sharp scatterings were found, the pattern of 2c exhibits
only two reflections preventing a doubtless evaluation. It can
be assumed that all phases are of the same type, because the
ratio of the observed reflections relative to the first one is the
same. Miscibility studies of these compounds with each other
also confirm this assumption (see below).
Alkyl DeriVatiVe 8. An exclusively smectic polymorphism
is found for the undecyl derivative 8, which has the same chain
length as the decyloxy compound 2c. On cooling the SA-phase,
an SC-phase and a smectic low-temperature phase can be
observed. The textures of the SA- and SC-phase correspond to
the known fan shape respectively broken fan shape textures.
The low-temperature phase is characterized by a paramorphotic
To get a deeper insight in the influence of protic solvents on
the mesomorphic properties the lyotropic phase behavior of
compound 2c was investigated in more detail. The binary phase
diagram of 2c with formamide constructed from DSC- heating
and -cooling scans is displayed in Figure 8. The interpretation

Novel Amphotropic Biphenyl Derivatives
J. Phys. Chem. B, Vol. 102, No. 27, 1998 5265
TABLE 3: Phase Transition Temperatures (°C) and Associated Enthalpy Values (kJ/mol, Lower Lines in Brackets) of the Pure
Laterally Substituted 4-Alkoxy-4′-(5,6-dihydroxy-3-oxapentyl)biphenyles 9-15 and Clearing Temperatures of the SA-Phases of
the Solvent Saturated Samples
Tcl ethylene
Tcl formamide
compd
Y
Z
cr
Col
SA-is
glycol saturated
saturated
9
F
H
H
H
98
(41.6)
80
(41.4)
78
(42.0)
59/75/92a
(2.1/4.1/41.3)
117
(44.7)
108
(24.5)
69/85a
(17.7/22.4)
155
(5.1)
141
(2.4)
131
(4.3)
109
(1.8)
137
(5.5)
139
(7.9)
130
(5.2)
124
133
104
99
163
181
152
159
169
159
145
10
11
12
13
14
15
CH3
CH3O
CH3
H
102
(0.1)
CH3O
F
120
125
97
H
CH3
CH3O
H
a Different crystalline modifications.
Figure 7. Small angle part of the X-ray diffraction pattern of the
columnar phase of compound 10.
Figure 6. Optical micrograph (crossed polarizers) of the texture of
the thermotropic columnar phase at 100 °C as obtained by cooling the
homeotropically aligned SA-phase of compound 10.
of the DSC-curves is based on microscopic observations. At
first considering the SA-is-transition, a slight increase of the
clearing temperature is observed on increasing the formamide
content of the sample. A maximum (T ) 185 °C) is reached at
a molar ratio of approximately 6 mol formamide/mol diol 2c.
On further addition of formamide, the clearing temperature
slightly decreases again. The solvent-saturated sample has a
clearing temperature of 173 °C. In contrast to the smectic
A-phase, the SC-phase and the columnar mesophase are strongly
destabilized and disappear at further increased solvent content.
The SC-phase can be observed up to a solvent content of ca.
3.6 mol formamide/mol 2c, whereas the columnar phase already
disappears at a ratio as small as 0.25 mol formamide per mol
diol 2c.
Figure 8. Phase diagram of the system 2c/formamide.8b
solvent penetration experiments (contact preparations), is given
in Figure 9. Here, the columnar phase is destabilized and a
smectic C-phase is induced at a certain formamide concentration.
Similar behavior was found for the long chain derivatives
2d-f. As a representative example, the simplified principal
phase diagram of the system 2f/formamide, obtained from
Also, the columnar mesophase of the methyl substituted
compound 10 is destabilized in favor of the SA-phase on addition

5266 J. Phys. Chem. B, Vol. 102, No. 27, 1998
Lindner et al.
Figure 11. Optical micrograph (crossed polarizers) of the induced
lyotropic columnar phase of compound 4 with formamide (T ) 83 °C,
45 wt % formamide).
Figure 9. Simplified phase diagram of the system 2f/formamide.
Figure 12. Phase diagram of the binary system 2e/2c.
Recently we have found, that the adjustment of the polar-
lipophilic interface curvature in thermotropic mesophases of
polyhydroxy amphiphiles is possible by mixing structurally
related polyhydroxy amphiphiles which have a different mo-
lecular shape.15 This method was for example used to distin-
guish between different types of cubic mesophases.15 In the
following we want to apply this method to get additional
information about the structure of the columnar mesophases of
compounds 2 and 10.
At first, binary mixtures of the compounds 2c-f differing
only in the alkyl chain length have been investigated. The
simplified binary phase diagram (obtained from contact prepara-
tions) for the system 2c/2e is given in Figure 12. Complete
miscibility between the smectic A-phases and the columnar
phases of the two components was found. Neither a phase
boundary in the columnar phase range nor a minimum in the
Col-SA-transition curve could be detected. In the contact
region, the optical textures of the columnar phases gradually
change. This can also be observed for the other binary systems
and confirms that all the columnar phases in this class of
compounds have an identical structure, despite of the fact that
they display different textures.
Figure 10. Phase diagram of the system 4/formamide.
of protic solvents. However, contrary to the derivatives 2, no
smectic C-phase can be detected at any solvent concentration.
The influence of the size of the hydrophilic group on the
lyotropic phase behavior is obvious from the comparison of the
phase diagrams of the mono(oxyethylene) derivative 2c with
formamide (Figure 8) and the phase diagram of the tris-
(oxyethylene) derivative 4 with formamide (Figure 10). In both
cases, the SA-phase is stabilized at first and then destabilized,
and the SC-phases are strongly destabilized and disappear with
increasing formamide content. It is, however, remarkable that
a new monotropic mesophase can be induced in the formamide
rich region of the phase diagram of the tris(oxyethylene)-
derivative 4 (Figure 10). This induced mesophase is character-
ized by a typical spherulitic texture (see Figure 11) which is
often observed for columnar mesophases. Because of the fact
that this mesophase occurs at a large excess of formamide (8-
22 mol formamide/mol of 4) and taking in account the rather
large size of the hydrophilic group of compound 4, we assume
that this phase can be a hexagonal columnar phase (direct phase
HI) consisting of cylindrical micelles as often observed in
lyotropic systems or a ribbon phase as recently proposed for
thermomesophases of rod-coil molecules with extended oligo-
(oxyethylene) chains.2 Because of the metastable character this
mesophase could not be proved using X-ray method.
In a second step we investigated binary mixtures of the
compounds 1, 2e, and 3 with each other. These compounds
have identical alkyl chain length and differ only in the number
of oxyethylene units between diol unit and rigid core, (i.e., in
the size of the hydrophilic group). Though the SA-phases of
the compounds 2e and 3 are completely miscible, a sharp phase
boundary with an extended two phase region separates the
smectic C-phase of 3 from the columnar phase of 2e (Figure
3.3. Binary Mixtures of Different Biphenyl Derivatives.

Novel Amphotropic Biphenyl Derivatives
J. Phys. Chem. B, Vol. 102, No. 27, 1998 5267
Figure 13. Binary phase diagram of the system 3/2e.
13). This means that the columnar phase gets lost on increasing
the average size of the hydrophilic groups in the mixed system.
Much more important is the fact that, in the contact region of
the diol 1 without polyether chain and the SC-phase of the
diethylene glycol derivative 3, the typical texture of the columnar
mesophase of compound 2e is observed in the temperature range
between 124 and 131 °C. No columnar phase can be detected
for the pure compound 3 down to 122 °C. Probably some of
the compound 1 dissolves in the SC-phase of 3 and induces the
columnar mesophase. This means that the columnar phase
appears if the average size of the hydrophilic groups is
decreased. It is also possible that, in the contact region, the
melting point of 1 is depressed and therefore a hidden mono-
tropic columnar phase can be observed. Unfortunately, the SA-
phase of the pure compound 1 crystallizes at 176 °C and cannot
be supercooled at all. Therefore we can only speculate on the
existence of a monotropic Colob phase of this compound.
Nevertheless, this observation indicates that the Colob-phase can
only be found for biphenyl derivatives with a relatively small
polar group.
Figure 14. Binary phase diagram of the system 10/2e.
The columnar phases of the compounds 2c-f are depressed
and replaced by the SA-phase upon addition of the biphenyl
derivatives 13-15 with polar or nonpolar lateral substituents
next to the hydrophilic group and also upon addition of the
compounds 9 and 11 that have polar substituents in neighbor-
hood to the alkyl chain.
Figure 15. Texture (crossed polarizers) of the columnar phase (ColX)
appearing in the binary system10/2e at x2e ) 0.75 and T ) 130 °C.
TABLE 4: Observed Reflections of the Binary Mixture x2e
) 0.46, x10 ) 0.54 in the Cubic Phase
The binary phase diagrams of the methyl substituted com-
pound 10 with the 4′-alkoxybiphenylderivatives 2 are much
more complicated. The detailed phase diagram of the system
2e/10 is given in Figure 14. Again, complete miscibility is
found between the smectic A-phases of both compounds.
However, the columnar phases of these two compounds do not
have an uninterrupted miscibility. This confirms the assumption
that the two columnar phases could be of a different type. In
the contact region two induced phases occur. Upon increasing
the ratio 2e/10, the columnar phase of the methyl-substituted
compound 10 is at first stabilized, but in the middle concentra-
tion range (x2e ) 0.4-0.7), another phase occurs. This phase
appears optically isotropic. It grows with cornered phase
boundaries, and it is significantly more viscous than the
neighboring columnar mesophases. These are typical features
of cubic phases. More detailed inspection between crossed
polarizers reveals the presence of a very dim mosaic like texture
consisting of homogeneous areas, some of them appearing not
completely dark. Such a pattern has been observed for other
thermotropic cubic phases16 and probably could be caused by
the polycrystalline nature of the samples. This optically
isotropic mesophase was investigated by X-ray diffraction by
the Guinier film method. In the small angle region seven sharp
reflections appear, which could be indexed on the basis of a
Θ
exp(deg)
Θ
cal(deg)
hkl
0.83
0.97
1.16
1.36
1.58
1.65
1.79
111
200
211
220
311
222
321
0.96
1.17
1.35
1.59
1.66
1.79
cubic lattice (Table 4). According to the observed systematic
extinctions, the space groups Pn3m and Pn3 are compatible with
the experimental results. The obtained lattice constant a ) 9.22
nm is much larger than twice the estimated molecular length
(2L ∼ 6.4 nm from CPK-models).
At a molar fraction of x2e ∼ 0.75, another columnar phase
(ColX) is induced in a very small region between the cubic and
Colob phases. This induced phase has a spherulitic texture
(Figure 15). The small existence range prevents a further
characterization by X-ray studies.
The principal phase diagrams (obtained from contact prepara-
tions) of the binary systems of the methyl-substituted compound
10 with other homologues 2 are displayed in Figures 16a-c.
Interestingly, increasing the chain length of the compounds 2

5268 J. Phys. Chem. B, Vol. 102, No. 27, 1998
Lindner et al.
4. Discussion
In summary we have found that single chain amphiphiles
incorporating biphenyl rigid rods (compounds 2c-f and 10) can
form columnar phases despite of the fact that they are neither
disklike nor tapered shaped and the parallel arrangement of the
individual molecules should favor smectic layer structures. The
preliminary X-ray studies performed at nonoriented samples
point to a two-dimensional oblique structure of these columnar
phases.
From the different textures, from X-ray results, and from
miscibility studies we conclude that the Colob phases of the
compounds 2c-f differ significantly from that one of the 3′-
methyl-substituted compound 10.
In the columnar phases of the compounds 2c-f the d-value
of the smectic phase above the columnar phase corresponds to
one of the lattice parameter of the columnar phase. Therefore,
we assume that these columnar mesophases may result from
the collapse of the smectic layer structure into ribbons. Such
ribbon structures17,18 have already been described for thermo-
tropic phases of soaps.19 They are also under discussion in
relation to mesophases of polycatenar20b and double-swallow-
tailed21 compounds, mesogens with fluorinated terminal chains,22
and facial calamitic amphiphiles.24 Ribbon phases can also
appear as intermediate phases between single-layer and double-
layered smectic phases of polar calamitic 4-nitrobenzoates and
4-cyanobenzoates23 and in mixtures consisting of amphiphilic
and bolaamphiphilic mesogens.24 In most cases the collapse
of layers results from a frustration caused by the different space
filling of incompatible parts of the individual molecules (e. g.,
headgroup lattice and alkyl chains in the case of alkali metal
carboxylates, rigid cores, and alkyl chains in the case of
polycatenar and swallow-tailed compounds).
In the compounds 1-15 the hydrophilic groups strongly
interact via large dynamic hydrogen bonding networks and give
rise to stable bilayer structures. These bilayer structures are
further reinforced by the rigid biphenyl cores, which prefer a
parallel arrangement within the smectic layers.10,25 The polar
and the rigid parts can segregate from the flexible lipophilic
alkyl chains into different regions. At elevated temperatures,
the space filling of these regions seems to be nearly equivalent,
and therefore, an SA bilayer structure is observed. It is well-
known that the molecular motion and bond reorientation
processes are temperature dependent. The decrease of the
temperature can differently influence the hydrogen bonding
networks, the arrangement of the biphenyl units, and the
conformation of the alkyl chains. This could give rise to a
different cross section of the polar and the lipophilic regions in
dependence on the temperature. It was observed that the
columnar phase is only found for the derivatives with long
lipophilic chains and that it is lost by increasing the size of the
hydrophilic groups either by elongation of the oxyethylene
chains or by hydration with protic solvents. Therefore, it seems
likely that in the columnar mesophase the cross section of the
polar regions is smaller than that of the lipophilic regions.26
The columnar phase occurs on cooling the SA-phase. This
would mean that the average cross section of the hydrophilic
groups decreases to a greater degree upon cooling than that of
the lipophilic alkyl chains. This fact can be explained, if one
assumes a reorganization of the hydrogen bonding network at
the transition from the smectic to the columnar phase, which
allows a more efficient packing in the polar region. The
resulting different space filling within the segregated regions
gives rise to a frustration within the layers which causes their
collapse with formation of ribbons arranged in a oblique lattice.
Figure 16. Simplified binary phase diagrams of the systems (a) 10/
2a, (b) 10/2c, and (c) 10/2f.
leads to increased stability of the induced columnar (2a, 129
°C; 2c, 132 °C; 2e, 135 °C) and the induced cubic phases (2a,
117 °C; 2c, 123 °C; 2e, 130 °C; 2f, 145 °C). In the binary
system 10/2f, however, no induced columnar phase is observed.
It seems that the cubic phase is more strongly stabilized and
therefore completely replaces the columnar phase (ColX) in this
binary system.
On mixing the short chain compounds 2a and 2c with 10
their SC-phases disappear (Figures 16a and b). The SC-phase
of compound 2a is replaced by a second induced mesophase
which occurs beside the ColX-phase (see Figure 16a). The
optical texture of this induced columnar phase corresponds to
that one of the Colob mesophase of the pure compounds 2c and
d (Figure 2a). Therefore, we assume that this induced phase
could correspond to the columnar mesophases (Colob) of the
pure compounds 2.

Novel Amphotropic Biphenyl Derivatives
J. Phys. Chem. B, Vol. 102, No. 27, 1998 5269
Figure 18. Model proposed for cubic mesophases of inverted lyotropic
systems with a Pn3m lattice.27
From the discussion given for this ternary lyotropic system, it
can be assumed that the cubic phase occurring in the mixed
system 2/10e could also be built up by interwoven networks of
ribbons.
With respect to the mesophases observed (smectic, columnar,
and cubic), the same diversity of different kinds of mesophases,
as in the lyotropic and thermotropic phase sequence of am-
phiphilic molecules and block copolymers and as in the
thermotropic phase sequence of polycatenar compounds, is
found. The proposed model of the arrangement of the individual
molecules in the mesophases is similar to that of polycatenar
compounds.20 The main difference is that not the individual
molecules but extended hydrogen bonded bilayer-aggregates
form the ribbons and that only one terminal chain is attached
to each rigid core. In this respect, the compounds 2 and 10 are
related to the rodlike hydrogen-bonded dimers of 3′-substituted
4′-alkoxybiphenylcarboxylic acids28,32 and to the ion pair
complexes formed by silver(I) complexes of 4-alkoxystilbazoles,
associated to alkylsulfonate anions,33 which both show cubic
mesophases.
Figure 17. Schematic representation of a possible arrangement of the
molecules in the Colob-phases of the compounds 2.
Because of the fact that one of the lattice parameter of the Colob-
phase agrees well with the layer thickness of the neighboring
SA-phase, it seems likely that the molecules have a nontilted
arrangement. However, in the case of the appearance of a
smectic C-phase above the columnar phase of compound 2c
and on addition of protic solvents to the compounds 2d-f, a
tilted arrangement of the molecules cannot be totally excluded
at present.
With only one exception, all laterally substituted compounds
exclusively display the smectic A-phase. It supposes that the
additional lateral steric effect connected with a decrease of the
core-core interactions and an increase of the cross section in
this molecular moiety prevents the formation of the ribbons.
The only one exception from this is found in the 3′-methyl-
substituted compound 10. From investigation of the columnar
phase of compound 10 and from miscibility studies with
compounds 2, we found that the columnar phase of 10
significantly differs from the columnar phases of the compounds
2c-f.
In mixed systems consisting of the 3′-methyl-substituted
compound 10 and the compounds 2 without lateral substituents,
the smectic C-phases of compounds 2a-c are replaced by the
Colob-phase. Probably the methyl-substituted compound 10
increases the average cross section of the lipophilic chain region
which causes the transition from a SC-phase to the Colob-phase.
Most remarkable is the fact that in all cases a cubic phase is
induced in these mixed systems. The cubic phase in the system
2e/10 can have either a Pn3m or a Pn3 space group. The
position of this cubic phase between two columnar mesophases
(regarding the concentration) is quite unusual. However, with
respect to the temperature regime (see Figure 14), the cubic
phase occurs on cooling a smectic A-phase before the transition
to a columnar phase or crystallization. Cubic phases can often
be observed as intermediate phases between smectic and
columnar mesophases.27,28 In most cases Ia3d and Im3m cubic
lattices have been found. Cubic phases with a Pn3m lattice29
have, for example, been detected in some lyotropic systems as
intermediate phases between the smectic and the inverted
columnar mesophase.27,30 It was proposed that these cubic
phases consist of two interwoven tetrahedral networks containing
the polar regions arranged in a double diamond lattice as shown
in Figure 18, separated by the F-minimal surface.
To clarify the complex phase behavior of this type of
compounds, further synthetic activities, and detailed investiga-
tions are in progress.
5. Experimental Section
5.1. General Considerations. Confirmation of the structures
of intermediates and products was obtained by 1H spectroscopy
(VARIAN Unity 500, VARIAN Gemini 200 spectrometer), by
infrared spectroscopy (SPECORD 71), and by mass spectrom-
etry (Intectra GmbH, AMD 402, electron impact, 70 eV). The
purity of all compounds was checked by thin-layer chromatog-
raphy (TLC aluminum sheets, silica gel 60 F254 from Merck).
Microanalyses were performed using an LECO CHNS-932
elemental analyzer.
Transition temperatures were measured using a Mettler FP
82 HT hot stage and control unit in conjunction with a Nikon
Optiphot-2 polarizing microscope and were confirmed using
differential scanning calorimetry (Perkin-Elmer DSC-7). X-ray
studies were performed by means of a Guinier-goniometer (Fa.
HUBER). 4-Bromo-2-fluorophenol (Aldrich), 4-bromo-2-meth-
oxyphenol (Lancaster), 4-iodo-2-methylphenol (Aldrich), â-AD-
mix (Aldrich), osmium tetroxide (Berlin Chemie), and N-methyl
morpholine-N-oxide solution (Aldrich) were used as obtained.
2-Allyloxyethanol,34 4-undecyloxy bromobenzene,35 1-toluyl-
sulfonyloxy-2-oxa-5-hexene,36 4-alkoxy bromobenzenes,37,38
4-octyloxyphenylboronic acid (6a),39 4-decyloxyphenylboronic
acid (6b),40 and compound 2b41 were obtained according to the
procedures described in the corresponding references.
5.2. Etherification of Phenols: General Procedure. The
appropriate substituted phenol (58 mmol) was dissolved in 200
mL dry acetonitrile. K2CO3 (24 g, 175 mmol), the appropriate
1-bromoalkane (60 mmol), and Bu4NI (100 mg) were added
and the mixture was stirred at 100 °C for 4-8 h. Afterward
the solvent was removed in vacuo and the residue was dissolved
in water (100 mL) and ether (150 mL). The organic layer was
In the mixed systems 2/10, the cubic phase occurs neighboring
a smectic A-phase and close to a columnar mesophase composed
of ribbons. A cubic phase composed of ribbons was recently
proposed for an Im3 cubic phase of a ternary lyotropic system
between a lamellar and a rectangular columnar mesophase.31

5270 J. Phys. Chem. B, Vol. 102, No. 27, 1998
Lindner et al.
separated and the aqueous solution was extracted twice with
ether (50 mL). The combined solutions were washed with water
(100 mL) and with brine (50 mL). After drying (Na2SO4), the
solvent was removed. The products were purified either by
column chromatography or by repeated crystallization from
ethanol.
4-Bromo-1-tetradecyloxybenzene. Yield 81%; mp 40 °C;
1H NMR (CDCl3, 500 MHz) δ ) 7.36 (2H, d, J ) 8.2, Ar-H),
6.95 (2H, d, J ) 8.2, Ar-H), 3.99 (2H, t, J ) 6.8 Hz, CH2O),
1.75 (2H, m, CH2CH2O), 1.51-1.25 (22H, m, CH2), and 0.88
(3H, t, J ) 6.5 Hz, CH3).
Hz, CH2-Ar), 1.65 (2H, m, CH2CH2-Ar), 1.2-1.3 (16H, m,
CH2), 0.88 (3H, t, J ) 6.4 Hz, CH3).
4-Dodecyloxy-3-fluorphenylboronic Acid (6 g). Yield 59%;
1H NMR (CDCl3, 200 MHz) δ ) 7.91 (1H, d, J ) 8.6 Hz,
Ar-H), 7.86 (1H, d, J ) 11.5 Hz, Ar-H), 7.05 (1H, dd, J )
8.0 Hz, J ) 8.0 Hz, Ar-H), 4.11 (2H, t, J ) 6.5 Hz, CH2O),
1.87 (2H, m, CH2CH2O), 1.2-1.6 (18H, m, CH2), 0.88 (3H, t,
J ) 6.7 Hz, CH3); 19F NMR (CDCl3, 188 MHz) δ ) -137.46
(dd, J ) 11.5 Hz, J ) 8.0 Hz, Ar-F).
4-Dodecyloxy-3-methylphenylboronic Acid (6h). Yield
1
83%; H NMR (CDCl3, 200 MHz) δ ) 8.03 (1H, d, J ) 8.2
4-Bromo-1-dodecyloxy-3-fluorobenzene. Yield 78%, oily
Hz, Ar-H), 7.96 (1H, s, Ar-H), 6.90 (1H, d, J ) 8.2 Hz, Ar-
H), 4.03 (2H, t, J ) 6.4 Hz, CH2O), 2.30 (3H, s, CH3O), 1.83
(2H, m, CH2CH2O), 1.2-1.9 (18H, m, CH2), 0.87 (3H, t, J )
6.3 Hz, CH3).
1
liquid; H NMR (CDCl3, 500 MHz) δ ) 7.2 (1H, d, J ) 10.7
Hz, Ar-H), 7.14 (1H, d, J ) 6.5 Hz, Ar-H), 6.8 (1H, t, Ar-
H), 3.97 (2H, t, J ) 6.6 Hz, ArOCH2), 1.78 (2H, m,
ArOCH2CH2), 1.26 (18 H, m, CH2), 0.87 (3H, t, J ) 6.9 Hz,
CH3).
4-Dodecyloxy-3-methoxyphenylboronic Acid (6i). Yield
52%; mp 118-120 °C; 1H NMR (CDCl3, 200 MHz) δ ) 7.84
(1H, dd, J ) 1.4 Hz, J ) 8.0 Hz, Ar-H), 7.70 (1H, d, J ) 1.2
Hz, Ar-H), 7.01 (1H, d, J ) 8.0 Hz, Ar-H), 4.11 (2H, t, J )
6.8 Hz, CH2O), 4.00 (3H, s, CH3O), 1.5-2.0 (20H, m, CH2),
0.86 (3H, t, J ) 6.3 Hz, CH3).
4-Dodecyloxy-1-iodo-3-methylbenzene. Yield 85%, oily
1
liquid; H NMR (CDCl3, 200 MHz) δ ) 7.39 (2H, d, Ar-H),
6.54 (1H, d, J ) 9.2 Hz, Ar-H), 3.89 (2H, t, J ) 6.3 Hz,
ArOCH2), 2.15 (3H, s, Ar-CH3), 1.76 (2H, m, ArOCH2CH2),
1.25 (18H, m, CH2), 0.87 (3H, t, J ) 6.7 Hz, CH3).
5.4. 4-Halo-1-(5,6-dihydroxy-3-oxahexyloxy)benzene De-
rivatives (7a-d). The appropriate substituted 4-halophenol (13
mmol) was dissolved in dry acetonitrile (50 mL). K2CO3 (4.6
g, 33 mmol), 1-toluylsulfonyloxy-2-oxa-5-hexene (3.4 g, 13
mmol), and Bu4NI (10 mg) were added, and the mixture was
stirred at 100 °C for 4-8 h. Afterward, the solvent was
removed in vacuo, and the residue was dissolved in water (50
mL) and ether (100 mL). The organic layer was separated,
washed with water (50 mL), and with brine (50 mL). After
drying (Na2SO4), the solvent was removed. The products were
purified by column chromatography (chloroform/methanol 10:
1). The solvent was evaporated and the oily residues were used
without further purification for the dihydroxylation. For this
purpose, the 4-halo-1-(3-oxa-5-hexenyloxy)benzene derivative
obtained (5.0 mmol) was dissolved in acetone (90 mL). To
this solution N-methylmorpholine-N-oxide (7.0 mmol, 10.7 mL
of an 60% solution in water) and osmium tetroxide solution (1
mL of 0.01 M% solution in tert-butyl alcohol) were added. The
resulting mixture was stirred for 100 h at room temperature.
After this time, starting materials could no longer be detected
and the mixture was worked up as follows: sodium bisulfite
(saturated solution, 30 mL) was added and the resulting slurry
was vigorously stirred for 1 h at room temperature. Afterward
the solids were filtered off through a pad of Celite. The Celite
was washed with acetone (100 mL), and the solution was
evaporated. The residue was dissolved in warm ethyl acetate
(200 mL) and the solution was washed with water (100 mL)
and brine (25 mL) and was finally dried over Na2SO4. After
evaporation of the solvent, the residue was purified by column
chromatography with chloroform /methanol mixtures. The
solvent was evaporated, and the highly viscous oily residues
were used as obtained.
4-Bromo-1-dodecyloxy-3-methoxybenzene. Yield 98%; mp
39 °C; 1H NMR (CDCl3, 200 MHz) δ ) 6.96 (2H, m, Ar-H),
6.71 (1H, d, J ) 8.2 Hz, Ar-H), 3.95 (2H, t, J ) 6.8 Hz,
ArOCH2), 3.82 (3H, s, ArOCH3), 1.78 (2H, m, ArOCH2CH2),
1.24 (18H, m, CH2), 0.86 (3H, t, J ) 6.8 Hz, CH3).
5.3. Phenylboronic Acids (6). A solution of the appropriate
bromobenzene derivative (25 mmol) in dry THF (150 mL) was
cooled with violent stirring to -78 °C. BuLi (16 mL of a 1.6
M solution in hexane, 26.0 mmol) was added dropwise within
2 h while the temperature was kept below -60 °C. The
suspension was stirred at -70 °C for 3 h and then trimethyl-
borate (5.4 g, 52.0 mmol) was added via a syringe. The
temperature was kept below -60 °C during the addition. The
reaction mixture was stirred for 2 h at -70 °C and then allowed
to warm to room temperature. After addition of 3 M hydro-
chloric acid (30 mL), the mixture was stirred for additional 1 h
at 20 °C. Afterward the solvent was evaporated and the residue
was extracted with ethyl acetate (2 × 100 mL). The combined
organic phases were washed with water (100 mL) and brine
(50 mL) and were dried with Na2SO4. After the evaporation
of the solvent, the residue was recrystallized from petroleum
ether. Some of the boronic acids were obtained as mixtures
containing oligomeric boronic acids. These mixtures can be
used for the cross-coupling reaction without further purification.
4-Undecyloxyphenylboronic Acid (6c). Yield 75%; mp
80-81 °C; 1H NMR (CDCl3, 200 MHz) δ ) 8.13 (2H, d, J )
8.6 Hz, Ar-H), 6.98 (2H, d, J ) 8.6 Hz, Ar-H), 4.02 (2H, d,
J ) 6.7 Hz, CH2O), 1.81 (2H, m, CH2CH2O), 1.2-1.5 (16H,
m, CH2), 0.87 (3H, t, J ) 6.6 Hz, CH3).
4-Dodecyloxyphenylboronic Acid (6d). Yield 69%; mp
60-68 °C;1H NMR (CDCl3, 200 MHz) δ ) 8.16 (2H, d, J )
8.6 Hz, Ar-H), 6.99 (2H, d, J ) 8.6 Hz, Ar-H), 4.03 (2H, t,
J ) 6.6 Hz, CH2O), 1.82 (2H, m, CH2CH2O), 1.2-1.5 (18H,
m, CH2), 0.89 (3H, t, J ) 6.4 Hz, CH3).
4-Bromo-1-(5,6-dihydroxy-3-oxahexyloxy)benzene (7a).
Yield 63%; mp 30 °C; elemental analysis (%), found (calcd for
C11H15BrO4) C 45.06 (45.38), H 5.34 (5.19); 1H NMR (CDCl3,
200 MHz) δ ) 7.35 (2H, d, J ) 9 Hz, Ar-H), 6.77 (2H, d, J
) 9.0 Hz, Ar-H), 4.07 (2H, t, J ) 4.6 Hz, ArOCH2CH2O),
3.9-3.5 (7H, m, ArOCH2CH2O, OCH2CHOHCH2OH).
4-Bromo-1-(5,6-dihydroxy-3-oxahexyloxy)-2-fluoroben-
zene (7b). Yield 28%; 1H NMR (CDCl3, 500 MHz) δ ) 7.15
(1H, dd, J ) 2.4 Hz, J ) 10.7 Hz, Ar-H), 7.10 (1H, d, J ) 8.8
Hz, Ar-H), 6.79 (1H, dd, J ) 8.8 J ) 8.8 Hz, Ar-H), 4.07
(2H, t, J ) 4.5 Hz, ArOCH2CH2O), 3.9-3.3 (9H, m,
4-Tetradecyloxyphenylboronic Acid (6e). Yield 66%; mp
1
67 °C; H NMR (CDCl3, 200 MHz) δ ) 8.13 (2H, d, J ) 8.6
Hz, Ar-H), 6.99 (2H, d, J ) 8.6 Hz, Ar-H), 4.04 (2H, t, J )
6.6 Hz, CH2O), 1.82 (2H, m, CH2CH2O), 1.2-1.6 (22H, m,
CH2), 0.86 (3H, t, J ) 6.4 Hz, CH3).
4-Undecylphenylboronic Acid (6f). Yield 66%; mp 50 °C;
1H NMR (CDCl3, 200 MHz) δ ) 8.14 (2H, d, J ) 8.6 Hz,
Ar-H), 7.49 (2H, d, J ) 8.6 Hz, Ar-H), 2.69 (2H, t, J ) 6.6

Novel Amphotropic Biphenyl Derivatives
J. Phys. Chem. B, Vol. 102, No. 27, 1998 5271
ArOCH2CH2O, OCH2CHOHCH2OH, OH); 19F NMR (CDCl3,
188 MHz) δ ) -132.27 (Ar-F, dd, J ) 8.8 Hz, J ) 10.7 Hz).
1-(5,6-Dihydroxy-3-oxahexyloxy)-4-iodo-2-methylben-
zene (7c). Yield 38%; 1H NMR (CDCl3, 200 MHz) δ ) 7.3-
7.5 (2H, m, Ar-H), 6.52 (1H, d, J ) 9.1 Hz, Ar-H), 4.03
(2H, t, J ) 11.6 Hz, ArOCH2CH2O), 3.9-3.4 (7H, m,
ArOCH2CH2O,OCH2CHOHCH2OH), 2.92 (2H, s, broad, OH),
2.14 (3H, s, CH3).
CH), 3.74-3.61 (4H, m, OCH2CHOHCH2OH), 2.67 (1H, s,
broad, OH, 2.07 (1H, s, broad, OH), 1.78 (2H, m, CH2CH2-
OAr), 1.45 (2H, m, CH2CH2CH2OAr), 1.4-1.2 (12H, m, CH2),
0.87 (3H, t, J ) 7.1 Hz, CH3); MS (70 eV) m/z (%) ) 444
(100, M+), 186 (33).
4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-undecyloxybiphenyl
(2d). Synthesized from 6c and 7a. Yield 51%; transitions (°C)
cr1 128, cr2 143, Colob 147, SA 171; elemental analysis (%),
found (calcd for C28H42O5) C 73.34 (73.33), H 9.26 (9.23); 1H
NMR (CDCl3, 200 MHz) δ ) 7.47 (4H, m, Ar-H), 6.97 (4H,
m, Ar-H), 4.17 (2H, t, J ) 4.9 Hz, ArOCH2CH2O), 3.99 (2H,
t, J ) 6.4 Hz, CH2OAr), 3.9-3.7 (3H, m, ArOCH2CH2O, CH),
3.8-3.6 (4H, m, OCH2CHOH-CH2OH), 2.70, (1H, d, J ) 5.0
Hz, CHOH), 2.12 (1H, dd, J ) 6.6 Hz, J ) 6.6 Hz, CH2OH)
1.79 (2H, m, CH2CH2OAr), 1.6-1.2 (16H, m, CH2), 0.89 (3H,
t, J ) 6.7 Hz, CH3); MS (70 eV) m/z (%) ) 458 (100, M+),
186 (54).
4-Bromo-1-(5,6-dihydroxy-3-oxahexyloxy)-2-methoxyben-
1
zene (7d). <sen>Yield 38%; H NMR (CDCl3, 500 MHz) δ
) 6.9-7.0 (2H, m, Ar-H), 6.72 (1H, d, J ) 4.3 Hz, Ar-H),
4.09 (2H, t, J ) 4.6 Hz, ArOCH2CH2O), 3.42 (s, 3H, OCH3),
3.5-3.9 (7H, m, ArOCH2CH2O,OCH2CHOHCH2OH).
(S)-4-Bromo-1-(5,6-dihydroxy-3-oxahexyloxy)benzene [(S)-
7a]. â-AD-Mix (10 g) was dissolved in H2O/tert-butanol (1:1,
80 mL). The solution was cooled to 0 °C. At this temperature,
4-bromo-1-(3-oxa-5-hexenyloxy)benzene (1.5 g, 6.0 mmol) was
added. The resulting mixture was stirred for 24 h at 0-1 °C.
After this time, starting materials could no longer be detected
and the mixture was worked up as described for the racemic
(S)-4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-dodecyloxybi-
phenyl [(S)-2e]. Synthesized from 6d and (S)-7a. Yield 48%;
transitions (°C) cr1 128, cr2 143, Colob 149, SA 171 is; elemental
analysis (%), found (calcd for C29H44O5) C 73.63 (73.69); H
9.31(9.38); [R]D ) 6.8° (25 °C, c ) 0.001 g/mL in CHCl3); ee
1
7a. The H NMR-spectrum corresponds to that one of the
racemic compound. The enantiomeric purity was determined
by Mosher’s method: ee ) 64%.
1
) 64%; H NMR (CDCl3, 200 MHz) δ ) 7.44 (4H, m, Ar-
5.5. Pd0-Catalyzed Cross Coupling of Aryl Bromides with
Phenyl Boronic Acids: General Procedure. In a two-necked
flask equipped with a reflux condenser and a magnetic stirring
bar, Pd(PPh3)4 (0.2 g, 5 mol %) was added under an argon
atmosphere to a mixture consisting of the halobenzene derivative
(3.4 mmol), the boronic acid (3.5 mmol), glyme (30 mL), and
1 M NaHCO3 solution (20 mL). The mixture was stirred at
reflux temperature for 5 h. After cooling, the solvent was
evaporated and the residue was dissolved in hot chloroform (100
mL). The organic phase was separated, and petroleum ether
was added. The precipitate formed was sucked off, and the
crude product obtained was purified by repeated crystallization
from petroleum ether/ethyl acetate/chloroform mixtures.
4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-octyloxybiphenyl (2a).
Synthesized from 6a and 7a. Yield 39%; transitions (°C) cr1
115, cr2 121, cr3 146, SC 153, SA 169 is; elemental analysis
(%), found (calcd for C25H36O5) C 72.29 (72.08), H 8.79 (8.71);
1H NMR (CDCl3, 500 MHz) δ ) 7.43 (4H, m, Ar-H), 6.93
(4H, m, Ar-H), 4.15 (2H, t, J ) 4.6 Hz, ArOCH2CH2O), 3.97
(2H, t, J ) 6.6 Hz, ArOCH2), 3.92-3.84 (3H, m, ArOCH2CH2O,
CH), 3.74-3.61 (4H, m, OCH2CHOHCH2OH), 1.78 (2H, m,
CH2CH2OAr), 1.45 (2H, m, CH2CH2CH2OAr), 1.4-1.2 (10H,
m, CH2), 0.87 (3H, t, J ) 7.1 Hz, CH3).
H), 6.93 (4H, m, Ar-H), 4.15 (2H, t, J ) 4.9 Hz, ArOCH2-
CH2O), 3.97 (2H, t, J ) 6.5 Hz, ArOCH2), 3.9-3.8 (3H, m,
ArOCH2CH2O, CH), 3.7-3.55 (4H, m, OCH2CHOHCH2OH),
1.78 (2H, m, CH2CH2OAr), 1.6-1.2 (18H, m, CH2), 0.86 (3H,
t, J ) 6.5 Hz, CH3) MS (70 eV) m/z (%) ) 471 (100, M+), 353
(12), 303 (12), 185 (80).
4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-tetradecyloxybi-
phenyl (2f). Synthesized from 6e and 7a. Yield 47%;
transitions (°C) cr1 130, cr2 139, Colob 147, SA 171; elemental
analysis (%), found (calcd for C31H48O5) C 73.17(73.73), H
9.23(9.66); 1H NMR (CDCl3, 500 MHz) δ ) 7.44 (4H, m, Ar-
H), 6.93 (4H, m, Ar-H), 4.15 (2H, t, J ) 4.6 Hz, ArOCH2-
CH2O), 3.97 (2H, t, J ) 6.6 Hz, ArOCH2), 3.92-3.83 (3H, m,
ArOCH2CH2O, CH), 3.74-3.61 (4H, m, OCH2CHOHCH2OH),
1.78 (2H, m, CH2CH2OAr), 1.45 (2H, m, CH2CH2CH2OAr),
1.4-1.2 (20H, m, CH2), 0.87 (3H, t, J ) 7.1 Hz, CH3); MS (70
eV) m/z (%) ) 499 (100, M+), 465 (10), 185 (57).
4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-undecylbiphenyl (8).
Synthesized from 6f and 7a. Yield 44%; transitions (°C) cr1
75, cr2 100, cr3 108, SI/F 119, SC 120, SA 165 is; elemental
analysis (%), found (calcd for C28H42O4) C 76.31(75.98), H,
9.69(9.56); 1H NMR (CDCl3, 500 MHz) δ ) 7.48 (2H, d, J )
8.8 Hz, Ar-H), 7.43 (2H, d, J ) 8.3 Hz, Ar-H), 7.20 (2H, d,
J ) 8.3 Hz, Ar-H), 6.95 (2H, d, J ) 9.0 Hz, Ar-H), 4.17
(2H, t, J ) 4.6 Hz, ArOCH2CH2O), 3.92-3.84 (3H, m,
ArOCH2, CH), 3.74-3.61 (6H, m, ArOCH2CH2O, OCH2-
CHOHCH2OH), 2.61 (2H,t, J ) 7.8 Hz, ArCH2), 1.61 (2H, m,
ArCH2CH2), 1.4-1.2 (16H, m, CH2), 0.87 (3H, t, J ) 6.8 Hz,
CH3); MS (70 eV) m/z (%) ) 442 (100, M+), 324 (45), 301
(10), 183 (74).
4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-nonyloxybiphenyl (2b).
Transitions (°C) cr1 118, cr2 146, SC 150, SA 171 is; elemental
analysis (%), found (calcd for C26H38O5) C 72.28 (72.53), H
1
8.94 (8.89); H NMR (DMSO-D6, 200 MHz) δ ) 7.50 (4H,
m, Ar-H) 6.97 (4H, m, Ar-H), 4.63 (1H, d, J ) 5.1 Hz, sec
OH), 4.47 (1H, t, J ) 5.7, prim OH), 4.10 (2H, t, J ) 4.7,
ArOCH2CH2O), 3.97 (2H, t, J ) 6.3 Hz, ArOCH2), 3.74 (2H,
t, J ) 4.7, ArOCH2CH2), 3.6-3.3 (5H, m, OCH2CHOHCH2-
OH), 1.69 (2H, m, ArOCH2CH2), 1.26 (12H, m, CH2), 0.85
(3H, t, J ) 6.3, CH3); MS (70 eV) m/z (%) ) 430 (71, M+),
312 (12), 186 (100).
4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-dodecyloxy-3′-fluor-
biphenyl (9). Synthesized from 4-dodecyloxy-3-fluorphenyl
boronic acid 6g and 7a. Yield 36%; transitions (°C) cr 98, SA
155 is; elemental analysis (%), found (calcd for C29H43FO5) C,
70.67(70.99); H, 8.77(8.83); 1H NMR (CDCl3, 200 MHz) δ )
7.43 (3H, m, Ar-H), 6.97 (4H, m, Ar-H), 4.15 (2H, t, J ) 4.5
Hz, ArOCH2CH2O), 4.04 (2H, t, J ) 6.6 Hz, ArOCH2), 3.95-
3.85 (3H, m, ArOCH2CH2O, CH), 3.78-3.6 (4H, m, OCH2-
CHOHCH2OH), 1.85 (2H, m, CH2CH2OAr), 1.5-1.2 (18H, m,
CH2), 0.86 (3H, t, J ) 6.8 Hz, CH3); 19F NMR (CDCl3, 188
4′-Decyloxy-4-(5,6-dihydroxy-3-oxahexyloxy)biphenyl (2c).
Synthesized from 6b and 7a. Yield 16%; transitions (°C) cr1
120, cr2 143, Colob 146, SC 147, SA 171; elemental analysis
(%), found (calcd for C27H40O5) C 72.03 (72.94), H 8.90 (9.07);
1H NMR (CDCl3, 500 MHz) δ ) 7.43 (4H, m, Ar-H), 6.93
(4H, m, Ar-H), 4.15 (2H, t, J ) 4.6 Hz, ArOCH2CH2O), 3.97
(2H, t, J ) 6.6 Hz, CH2OAr), 3.93-3.83 (3H, m, ArOCH2CH2O,

5272 J. Phys. Chem. B, Vol. 102, No. 27, 1998
Lindner et al.
MHz) δ ) -135.93 (t, Ar-F); MS (70 eV) m/z (%) ) 490
3.97 (2H, t, J ) 6.6 Hz, CH2OAr), 3.93-3.85 (3H, m,
ArOCH2CH2O, CH), 3.74-3.62 (4H, m, OCH2CHOHCH2OH),
2.27 (3H, s, CH3-Ar), 1.78 (2H, m, CH2CH2OAr), 1.45 (2H,
m, CH2CH2CH2OAr), 1.4-1.1 (16H, m, CH2), 0.86 (3H, t, J
) 7.1 Hz, CH3); MS (70 eV) m/z (%) ) 486 (100, M+), 368
(11), 200 (45).
4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-dodecyloxy-3-meth-
oxybiphenyl (15). Synthesized from 6d and 7d. Yield 49%;
transitions (°C): cr1 69, cr2 85, SA 130; elemental analysis (%),
found (calcd for C30H46O6) C, 70.49(71.68); H, 8.94(9.22); 1H
NMR (CDCl3, 500 MHz) δ ) 7.43 (2H, d, J ) 8.8 Hz, Ar-
H), 7.04 (2H, m, Ar-H), 6.92 (3H, m, Ar-H), 4.19 (2H, t, J
) 4.9 Hz, ArOCH2CH2O), 3.97 (2H, t, J ) 6.6 Hz, CH2OAr),
3.92-3.87 (m, 6H, ArOCH2CH2O, CH, OCH3), 3.72-3.61 (4H,
m, OCH2CHOHCH2OH), 1.78 (2H, m, CH2CH2OAr), 1.45 (2H,
m, CH2CH2CH2OAr), 1.4-1.2 (16H, m, CH2), 0.87 (3H, t, J
) 7.1 Hz, CH3); MS (70 eV): m/z (%) ) 502 (100, M+), 468
(8, M+-CH2dCOHCH2OH), 428 (10), 384 (33), 216 (52, HO-
PhOMe-Ph-OH).
(100, M+), 322 (36), 204 (96).
4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-dodecyloxy-3′-meth-
ylbiphenyl (10). Synthesized from 4-dodecyloxy-3-methyl-
phenyl boronic acid 6h and 7a. Yield 39%; transitions (°C) cr
80, Colr 102, SA 141 is; elemental analysis (%), found (calcd
for C30H46O5) C, 73.76(74.04); H, 9.51(9.53); 1H NMR (CDCl3,
500 MHz) δ ) 7.45 (2H, d, J ) 8.8 Hz, Ar-H), 7.29 (2H, m,
Ar-H), 6.94 (2H, d, J ) 8.8 Hz, Ar-H), 6.83 (1H, d, J ) 8.1
Hz, Ar-H), 4.15 (2H, t, J ) 4.6 Hz, ArOCH2CH2O), 3.97 (2H,
t, J ) 6.6 Hz, CH2OAr), 3.92-3.83 (3H, m, ArOCH2CH2O,
CH), 3.75-3.61 (4H, m, OCH2CHOHCH2OH), 2.25 (3H, s,
CH3-Ar), 1.79 (2H, m, CH2CH2OAr), 1.46 (2H, m, CH2CH2-
CH2OAr), 1.4-1.2 (16H, m, CH2), 0.86 (3H, t, J ) 7.1 Hz,
CH3); MS (70 eV): m/z (%) ) 486 (100, M+), 452 (9), 412
(6), 318 (14, M+-C12H25), 200 (52).
4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-dodecyloxy-3′-meth-
oxybiphenyl (11). Synthesized from 4-dodecyloxy-3-meth-
oxyphenyl boronic acid 6i and 7a. Yield 51%; transitions (°C)
cr 78, SA 131 is; elemental analysis (%), found (calcd for
Acknowledgment. This work was supported by the Deutsche
Forschungsgemeinschaft, the Fonds der Chemischen Industrie,
and the IASTE exchange program (J.J.).
1
C30H46O6) C, 71.40(71.68); H, 9.22(9.22); H NMR (CDCl3,
500 MHz) δ ) 7.45 (2H, d, J ) 8.8 Hz, Ar-H), 7.04 (2H, m,
Ar-H), 6.9-7.0 (3H, m, Ar-H), 4.15 (2H, t, J ) 4.6 Hz,
ArOCH2CH2O), 4.02 (2H, t, J ) 6.8 Hz, CH2OAr), 3.92-3.83
(6H, m, ArOCH2CH2O, CH, CH3OAr), 3.74-3.61 (4H, m,
OCH2CHOHCH2OH), 1.84 (2H, m, CH2CH2OAr), 1.45 (2H,
m, CH2CH2CH2OAr), 1.4-1.2 (16H, m, CH2), 0.87 (3H, t, J
) 7.1 Hz, CH3); MS (70 eV) m/z (%) ) 502 (100, M+), 334
(35, M+-C12H25), 216 (38).
References and Notes
(1) (a) Percec, V.; Heck, J.; Johansson, G.; Tomazos, D.; Kawasumi,
M.; Ungar, G. J. Macromol. Sci., Pure Appl. Chem. 1994, A31, 1031. (b)
Stebani, U.; Lattermann, G. Macromol. Rep. 1995, A32 (Suppl. 3) 385. (c)
Pegenau, A.; Go¨ring, P.; Tschierske, C. J. Chem. Soc, Chem. Commun.
1996, 2563. (d) Cameron, J. H.; Facher, A.; Lattermann, G.; Diele, S. AdV.
Mater. 1997, 9, 398.
4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-dodecyloxy-3-methoxy-
3′-methylbiphenyl (12). Synthesized from 4-dodecyloxy-3-
methylphenylboronic acid 6h and 7d. Yield 71%; transitions
(°C) cr1 59; cr2 75; cr3 92; SA 109 is; elemental analysis (%),
found (calcd for C31H48O6) C, 70.03(72.06); H, 9.33(9.36); 1H
NMR (CDCl3, 500 MHz) δ ) 7.29 (2H, m, Ar-H), 7.04 (2H,
m, Ar-H), 6.92 (1H, d, J ) 8.8 Hz, Ar-H), 6.83 (1H, d, J )
8.8 Hz, Ar-H), 4.19 (2H, t, J ) 4.6 Hz, ArOCH2CH2O), 3.97
(2H, t, J ) 6.3 Hz, CH2OAr), 3.94-3.86 (6H, m, ArOCH2CH2O,
CH, OCH3), 3.72-3.61 (4H, m, OCH2CHOHCH2OH), 2.26
(3H, s, CH3-Ar), 1.80 (2H, m, CH2CH2OAr), 1.47 (2H, m,
CH2CH2CH2OAr), 1.4-1.2 (16H, m, CH2), 0.87 (3H, t, J )
7.1 Hz, CH3); MS (70 eV) m/z (%) ) 516 (100, M+), 398 (18),
230 (38).
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4-(5,6-Dihydroxy-3-oxahexyloxy)-4′-dodecyloxy-3-fluorbi-
phenyl (13). Synthesized from 6d and 7b. Yield 23%;
transitions (°C) cr 117, SA 137; elemental analysis (%), found
(calcd for C29H43FO5) C, 71.07(70.99); H, 9.06(8.83); 1H NMR
(CDCl3, 500 MHz) δ ) 7.42 (2H, d, J ) 8.8 Hz, Ar-H), 7.27-
7.20 (2H, m, Ar-H), 7.00 (1H, t, J ) 8.6 Hz, Ar-H), 6.93
(2H, d, J ) 8.8 Hz, Ar-H), 4.21 (2H, t, J ) 4.6 Hz, ArOCH2-
CH2O), 3.97 (2H, t, J ) 6.6 Hz, CH2OAr), 3.92-3.85 (3H, m,
ArOCH2CH2O,CH), 3.74-3.62 (4H, m, OCH2CHOHCH2OH),
1.78 (2H, m, CH2CH2OAr), 1.45 (2H, m, CH2CH2CH2OAr),
1.4-1.2 (16H, m, CH2), 0.87 (3H, t,J ) 7.1 Hz, CH3); 19F NMR
(CDCl3, 188 MHz) δ ) -135.32 (t, J ) 8.8 Hz, Ar-F); MS
(70 eV) m/z (%) ) 490 (98, M+), 372 (28), 204 (100, HO-
PhF-PhOH).
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transitions (°C) cr 108, SA 139; elemental analysis (%), found
(calcd for C30H46O5) C, 73.54(74.03); H, 9.36(9.53); 1H NMR
(CDCl3, 500 MHz) δ ) 7.42 (2H, d, J ) 8.8 Hz, Ar-H), 7.30
(2H, m, Ar-H), 6.91 (2H, d, J ) 8.6 Hz, Ar-H), 6.84 (1H, d,
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