Synthesis and thermotropic liquid crystalline properties of calamitic molecules with laterally attached hydrophilic groups: Y-shaped three-block molecules which can form smectic and columnar mesophases

J O U R N A L O F

Synthesis and thermotropic liquid crystalline properties of calamitic

molecules with laterally attached hydrophilic groups: Y-shaped

three-block molecules which can form smectic and columnar

mesophases

C H E M I S T R Y

Rene Plehnert, Jo¨rg Andreas Schro¨ter and Carsten Tschierske*

Institute of Organic Chemistry, University Halle, D-06015 Halle, Kurt-Mothes-Str. 2, Germany.

E-mail: coqfx@mlucom6.urz.uni-halle.de

Received 23rd April 1998, Accepted 23rd September 1998

The synthesis and the thermotropic liquid crystalline properties of calamitic mesogens (p-terphenyl derivatives, a

biphenyl and a p-quintaphenyl derivative) with a laterally attached hydrophilic group (1,2-diol groups, primary and

secondary amides, polyether chains, crown ether units, carbohydrate units, a hydrazide, a quaternary ammonium

salt, a carboxylic acid and a sodium carboxylate) are reported. The compounds were investigated by means of

polarizing microscopy and calorimetry. The inﬂuence of the type of the polar group, of the length of the rigid core

and the position of the connection of the hydrophilic group with the rod-like rigid core have been investigated.

Many of these amphiphilic molecules can form monolayer S phases. If a suﬃcient amount of hydrogen bonding is

A

available their mesophase stability can be higher than that of related compounds with other lateral substituents.

Rectangular columnar mesophases can be found for compounds with rather large and ﬂexible polar lateral

substituents (polyether chains) ﬁxed to the center of the rigid terphenyl unit. These columnar phases should

represent ribbon phases resulting from the collapse of the smectic layers (modulated smectic phases). The proposed

model is also related to that suggested for supermolecular structures of triblock copolymers. Thus, these molecules

can be regarded as low molecular weight block compounds consisting of three diﬀerent and incompatible molecular

parts.

hydrophilic functional groups such as diol groups, polyether

chains, carbohydrate units or ionic groups were laterally

attached to a rigid rod-like oligo-p-phenylene rigid core. These

molecules are of special interest, because two diﬀerent organiz-

ing forces of liquid crystalline phases are perpendicularly

directed to each other in these compounds (Fig. 1). Firstly,

the tendency of the rigid calamitic units is to adopt an

orientational long range order which is characteristic for

thermotropic liquid crystals and provides nematic and smectic

mesophases. Secondly, there is the tendency of amphiphilic

molecules to segregate their incompatible (e.g. hydrophilic and

hydrophobic) parts into segregated regions, giving rise to large

aggregates which themselves are the basis of lamellar, columnar

or cubic thermotropic and lyotropic mesophases.8 In the

compounds described here, the parallel arrangement of the

rigid units should be disturbed by the segregation of hydro-

philic and hydrophobic parts of the molecules and, conversely,

the aggregation of the amphiphilic molecules should be dis-

turbed because of the unfavorable size and shape of their

lipophilic parts. Indeed, these unusual molecules represent a

new class of amphiphiles with an unique organization in

Langmuir ﬁlms at the air–water interface,9 but their liquid

crystalline behavior is also remarkable. They represent novel

amphotropic compounds10 which can form thermotropic as

well as lyotropic liquid crystalline phases.11,12 The lyotropic

phase behavior will be reported in detail in a separate paper.13

1. Introduction

Liquid crystalline materials are of great interest for material

science as well as for life science. Their properties can be tuned

by appropriate molecular design. Thus, it is well known that

the mesomorphic properties of calamitic liquid crystals can

largely be inﬂuenced by lateral substituents, like halogens,1–3

alkyl or alkoxy groups.4,5 This can inﬂuence the melting

points, the mesophase types, the dielectric properties, etc. In

most cases, however, a signiﬁcant mesophase destabilization

is connected with this structural variation. Especially large

lateral groups suppress smectic phases and therefore nearly all

calamitic mesogens with long lateral alkyl chains show exclus-

ively nematic phases.5 However, in rare cases lateral substitu-

ents can have a mesophase stabilizing eﬀect. The earliest

example was provided by the laterally substituted 5-alkoxy-

naphthoic acids.6 The smectic tendency of the chloro substi-

tuted naphthoic acid is remarkably high, whereas the naphthoic

acid without the lateral chloro substituent is only a nematic

liquid crystal. It seems that a signiﬁcant mesophase stabilizing

eﬀect is provided by the polar chloro substituent which can

override its steric disturbance.

Likewise suitable molecular design, especially the

introduction of electron withdrawing substituents like cyano

or nitro in laterally attached aromatic rings, can produce

strongly branched calamitic mesogens with unexpectedly high

mesophase stabilities.5,7

We have synthesized a novel class of liquid crystals in which

Fig. 1 Structure of the amphiphilic molecules under investigation.

J. Mater. Chem., 1998, 8, 2611–2626

2611

Herein we describe the synthesis and summarize the results

obtained during investigation of their thermotropic liquid

crystalline properties.

(compounds 33) to the 2∞-position and in some cases to the

3-position of the p-terphenyl unit.

2. Syntheses

Pd0-catalyzed cross-coupling reactions between aryl halides

and arylboronic acids (Suzuki coupling)14 represent the key

steps of all syntheses which are outlined in Schemes 1–5. There

are three diﬀerent approaches to the compounds 1–3 and

29–31 all carrying a lateral group connected via an ether

linkage to the 2∞-position of the p-terphenyl rigid core.

Compounds 1 and 3, which all have the 4,5-dihydroxy-2-

oxapentyl group but diﬀer in the type of the terminal substitu-

ents, have been synthesized starting with 4-(2,5-dibromo-

benzyloxymethyl )-2,2-dimethyl-1,3-dioxolane 36 (Scheme 1).

After cross-coupling of 36 with the appropriate 4-substituted

phenylboronic acids, the 1,2-O-isopropylidene protecting

groups were cleaved by acidolysis. In an analogous manner

the quinquaphenyl derivative 5 was obtained by cross coupling

of 36 with 4-(4-decyloxyphenyl)phenylboronic acid

(Scheme 1).

The terphenyl derivatives 29–31, which diﬀer in the structure

of the lateral group in the 2∞-position, and the optically active

compound (S)-1e were synthesized using another strategy

shown in Scheme 2 for the syntheses of compounds 29b and

29c. Here, the p-terphenyl rigid core was built up ﬁrst and the

lateral groups were introduced in a second step. This allowed

a broad variation of the lateral hydrophilic groups. 2,5-Bis(4-

decyloxyphenyl )toluene was obtained by cross coupling of

two equivalents of 4-decyloxyphenylboronic acid with 2,5-

dibromotoluene.15 The methyl group was brominated using

NBS.15 The 2,5-bis(4-decyloxyphenyl)benzyl bromide 3715

obtained was afterwards etheriﬁed with diﬀerent functionalized

alcohols, followed by deprotection, if necessary. The best

yields in the etheriﬁcation step were obtained using phase

transfer conditions. The optically active compound (S)-1e was

obtained by etheriﬁcation of 37 with enantiomerically pure

(R)-(−)-4-hydroxymethyl-2,2-dimethyl-1,3-dioxolane.

First the p-terphenyl derivatives 1 and 3 (1: R=alkoxy; 3:

R=alkyl, n=m=1) both carrying a lateral 4,5-dihydroxy-2-

oxapentyl group were synthesized and the inﬂuence of changes

of the terminal substituents R was investigated. Afterwards

we changed the structure of the rigid core. Besides m-terphenyl

derivative 4, a biphenyl derivative 6, a molecule without a

rigid unit 7 and a quinquaphenyl derivative 5 were synthesized.

In the next step the position of the lateral hydrophilic group

was shifted along the p-terphenyl unit (compounds 11 and

13). Finally, a wide variation of the structure of the lateral

hydrophilic group was carried out in the series of 4,4>-

didecyloxy-p-terphenyl derivatives by appending amido groups

(compounds 15–24), ionic groups (compounds 27 and 28),

polyether chains (compounds 29, 30 and 34) or crown ethers

2612

J. Mater. Chem., 1998, 8, 2611–2626

Scheme 3 Reagents and conditions: i, HOCH CH OCH CHLCH ,

Scheme 1 Reagents and conditions: i, NBS, AIBN, hn, CCl , reﬂux, 2

2

4

NaOH, Bu NHSO , H O, 60 °C, 12 h; ii, cat. OsO , NMMNO,

h; ii, NaOH, H O, Bu NHSO , 60 °C, 15 h; iii, cat. Pd(PPh ) ,

4

2

4

2

4

3 4

acetone–H O, 25 °C, 24 h.

Na CO , H O, benzene–EtOH, reﬂux, 4 h; iv, HCl, H O–EtOH,

2

3

2

reﬂux 2 h.

benzyl bromides 39 and 40, respectively.18 The benzyl bromides

39 and 40 were synthesized as outlined in Scheme 4.18

Also compound 7, the biphenyl derivative 6 and the

m-terphenyl derivative 4 were prepared in an analogous pro-

cedure to that given in Scheme 2 starting with 2,5-didecyloxy-

benzyl bromide,18 5-decyloxy-2-(4-decyloxyphenyl)benzyl

bromide19 and 3,5-bis(4-decyloxyphenyl)benzyl bromide,20

respectively.

All 2,5-bis(4-decyloxyphenyl)benzoyl derivatives 15–24

were synthesized according to Scheme 5. Cross-coupling of

methyl 2,5-dibromobenzoate is possible with NaHCO as base

3

in a water–glyme solvent system without saponiﬁcation during

the reaction (which would lead to a failure of the reaction).15

The 2,5-bis(4-decyloxyphenyl)benzoic acid 25 which is

obtained after saponiﬁcation is treated with oxalyl chloride21

to yield the acid chloride 26. The use of oxalyl chloride at low

temperatures is crucial, because other conditions (e.g. SOCl )

2

would lead to an intramolecular Friedel–Crafts acylation with

formation of 7-decyloxy-2-(4-decyloxyphenyl)ﬂuoren-9-one.

The acid chloride 26 was aminolyzed to give the amides 15–24.

The crown compounds 33 were obtained by esteriﬁcation of

25 with 2-hydroxymethyl substituted crown ethers. The

detailed procedure and the analytical data for the crown

compounds 33 are reported in a separate paper concerning

their monolayer behavior.22

Additionally, two ionic amphiphiles were synthesized. The

ammonium salt 28 was obtained by quaternization of triethyl-

amine with 37.23 The sodium carboxylate 27 was isolated after

saponiﬁcation of the methyl carboxylate 14.

Scheme 2 Reagents and conditions: i, cat. Pd(PPh ) , Na CO , H O,

3 4

2

3

2

benzene–EtOH, reﬂux, 4 h; ii, NBS, AIBN, hn, CCl , reﬂux, 2 h;

4

iii, NaOH, Bu NHSO , H O, reﬂux, 15 h; iv, HCl, H O–EtOH,

3. Experimental

4

2

reﬂux, 2 h.

3.1. General

Only compound 29a carrying the 7,8-dihydroxy-2,5-dioxa-

octyl group was prepared in a slightly diﬀerent way, as shown

in Scheme 3. The benzyl bromide 37 was at ﬁrst etheriﬁed with

2-allyloxyethanol.16 The resulting allyl ether 38 was dihy-

Conﬁrmation of the structures of intermediates and products

was obtained by 1H and 13C NMR spectroscopy (Varian

Unity 500 and Varian Gemini 200 spectrometers) and by mass

spectrometry (Intectra GmbH, AMD 402, electron impact,

70 eV). All materials were puriﬁed by chromatography and/or

recrystallization until constant transition temperatures were

obtained. The purity was checked by thin layer chromatogra-

phy (TLC, aluminum sheets, silica gel 60 F254 from Merck)

and elemental analysis. Some compounds take up moisture

during sample preparation which causes a deviation of the

microanalysis from the calculated values. In these cases the

droxylated using catalytic amounts of OsO in the presence of

4

the oxidant N-methylmorpholine N-oxide.17

The amphiphiles 11, 13 (Scheme 4), 34 and 35 (see Fig. 15)

carrying their lateral substituents in the 2-position (compound

11) or in the 3-position (compounds 13, 34 and 35) at the p-

terphenyl rigid core were obtained in an analogous manner to

the corresponding 2∞-substituted materials, starting with the

J. Mater. Chem., 1998, 8, 2611–2626

2613

Scheme 4 Reagents and conditions: i, C

10 21

iii, cat. Pd(PPh ) , Na CO , H O–EtOH, reﬂux, 4 h; iv, NBS, AIBN, hn, CCl , reﬂux, 2 h; v, NaOH, Bu NHSO , H O, reﬂux, 12 h; vi, HCl,

3 4

H O–EtOH, reﬂux, 2 h.

H Br, K CO , CH CN, reﬂux, 17 h; ii, BuLi, THF, −78 °C, then B(OMe) , −70 °C, then HCl, H O;

2

3

2

3

2

4

2

purity (>99%) was additionally checked by HPLC

(Merck-Hitachi, RP-18, CH Cl –methanol 151).

2

Microanalyses were performed using an LECO CHNS-932

elemental analyzer. 2,5-Dibromotoluene (Acros), N-bromo-

succinimide (Merck), oxalyl chloride (Lancaster), osmium

tetroxide (Berlin Chemie), N-methylmorpholine N-oxide solu-

tion (Aldrich), 4-hydroxymethyl-2,2-dimethyl-1,3-dioxolane

(Aldrich), (R)-(−)-4-hydroxymethyl-2,2-dimethyl-1,3-dioxol-

ane (Aldrich), 3-aminopropane-1,2-diol (Merck), 1-amino-1-

deoxy--glucitol (Fluka), 1-deoxy-1-methylamino--glucitol

(Acros) and 1,4,7,10,13-pentaoxa-16-azacyclooctadecane

(Aldrich) were used as obtained. 2-Allyloxyethanol, phenylbo-

ronic acids,24 4-(7-hydroxy-2,5-dioxaheptyl)-2,2-dimethyl-1,3-

dioxolane,25 4-(10-hydroxy-2,5,8-trioxadecyl)-2,2-dimethyl-

1,3-dioxolane,25 4-(9-hydroxynonyl)-2,2-dimethyl-1,3-dioxol-

ane,26 bromomethyl-substituted 4,4>-didecyloxy-p-terphenyls

3715, 3918 and 4018 and methyl 2,5-bis(4-decyloxyphenyl)ben-

zoate 1415 were obtained according to the procedures described

in the corresponding references. Transition temperatures were

measured using a Mettler FP 82 HT hot stage and control

unit in conjunction with a Nikon Optiphot-2 polarizing micro-

scope and were conﬁrmed using diﬀerential scanning calor-

imetry (Perkin-Elmer DSC-7, the transition enthalpies are

collected in Table 1). Because some of the compounds are

very hygroscopic, the samples were dried prior to investigation

either in vacuo over phosphorus pentoxide for 48 h or by

heating for 1 min to a temperature of approximately 150 °C.

Afterwards the samples were immediately sealed and

investigated.

3.2. Synthesis of the terphenyl derivatives 1 and 3

3.2.1. 4-(2,5-Dibromobenzyloxymethyl)-2,2-dimethyl-1,3-

dioxolane 36. A solution of 2,5-dibromotoluene (20 mmol, 5 g)

and N-bromosuccinimide (24 mmol, 4.27 g) in dry tetrachloro-

methane (50 ml) was placed in a quartz ﬂask and heated to

the boiling point. AIBN (50 mg) was added and the reﬂuxing

mixture was irradiated with UV light (366 nm). After 2 h the

mixture was cooled to room temperature and the succinimide

formed was ﬁltered oﬀ. The solvent was removed in vacuo and

the residue was puriﬁed by crystallization from ethanol. Yield:

Scheme 5 Reagents and conditions: i, cat. Pd(PPh ) , NaHCO ,

3 4

Glyme, H O, reﬂux, 5 h; ii, NaOH, H O, reﬂux, 4 h; iii, HCl, H O,

3

2

reﬂux, 2 h; iv, (COCl) , 25 °C, 1 h; v, HNR1R2, DMF, 80 °C, 4 h.

2

2614

J. Mater. Chem., 1998, 8, 2611–2626

Table 1 Phase transition enthalpiesa

separated and the aqueous phase was extracted twice with

diethyl ether (50 ml). The combined organic phases were

washed with brine and dried with Na SO . The solvent was

removed in vacuo and the products obtained were puriﬁed by

column chromatography (silica gel, chloroform).

Compound

DH/kJ mol−1

2

4

1b K–Iso 43.2

S –Iso

1.2

3.8

4.4

6.1

6.8

7.6

8.0

A

1c K–S

1d K–S

1e K–S

1f K–S

1g K–S

1h K–S

37.2

50.5

55.5

66.2

60.7

70.7

S –Iso

A

S –Iso

A

S –Iso

4-[2,5-Bis(4-decyloxyphenyl)benzyloxymethyl]-2,2-

A

S –Iso

dimethyl-1,3-dioxolane. d (200 MHz, CDCl , J/Hz) 0.87 (t, J

A

H

3

S –Iso

A

6.7, 6H, CH ), 1.18–1.27 (m, 28H, CH ), 1.34 (s, 3H, CH ),

S –Iso

3

2

3

A

1.38 (s, 3H, CH ), 1.73–1.86 (m, 4H, OCH CH ), 3.42 (dd, J

9.8, 5.8, 1H, PhCH OCH H ), 3.53 (dd, J 9.7, 5.5, 1H,

PhCH OCH H ), 3.71 (dd, J 8.3, 6.3, 1H, OCH H ),

2

K–Iso 60.1

N–Iso 3.4

3

2

3b K–S

30.8

29.2

S –Iso

3.7

9.0

2.7

2

A B

A

5

6

K–S

K–Iso 24.7

S –Iso

A

2

A

B

A B

S –Iso

3.96–4.20 (m, 5H, OCH H , PhOCH ), 4.23–4.29 (m, 1H,

A

B

2

9

K–S

49.1

51.5

42.9

12.1

35.7

71.4

74.6

47.3

25.5

S –N

0.8 N–Iso 1.4

6.7

7.8

CHO), 4.50 (s, 2H, PhCH O), 6.93 (d, J 8.7, 2H, H-Ar), 6.96

A

C

A

2

10

11

12

13

17

18

19

20

22

S –Iso

A

(d, J 8.7, 2H, H-Ar), 7.26–7.28 (m, 2H, H-Ar), 7.29 (d, J 8.7,

S –Iso

A

1H, H-Ar), 7.48–7.53 (m, 1H, H-Ar), 7.55 (d, J 8.7, 2H,

H-Ar), 7.70 (d, J 1.8, 1H, H-Ar).

S –S –Iso 9.2

C

A

S –Iso

8.6

6.3

5.0

3.3

1.6

2.3

0.5

A

S –Iso

A

S –Iso

3.2.4. Deprotection of the 1,2-diol groups. The 2,2-dimethyl-

1,3-dioxolane derivatives obtained by the cross-coupling reac-

tions were used, without further puriﬁcation, for deprotection.

The appropriate 2,2-dimethyl-1,3-dioxolane derivative

(1 mmol) was dissolved in ethanol (50 ml) and 10% hydro-

chloric acid (10 ml) was added. Then, the mixture was heated

under reﬂux for 2 h. After cooling the solvent was evaporated

and 50 ml water and 50 ml diethyl ether were added to the

residue. The aqueous phase was extracted three times with

diethyl ether (30 ml). Afterwards, the combined organic phases

A

S –Iso

A

S –Iso

A

K–Iso 28.3

S –Iso

A

1.2 S –Iso

A

29b K–Iso 45.2 Col –S

r

A

29c K–Iso 43.2 Col –Iso 1.9

r

30b K–Iso 49.3

S –Iso

0.7

A

32

K–Iso 51.8

33a K–Iso 61.6

33b K–Iso 0.8

33c K–Iso 42.1

S –N

0.4 N–Iso 1.0

A

S –N–Iso 0.9

A

S –N

0.1 N–Iso 0.4

A

34a K–S

34b K–S

34c K–S

40.0

23.6

36.7

S –Iso

5.7

2.7

1.0

A

were washed with saturated NaHCO solution and water, and

S –Iso

3

A

S –Iso

dried with Na SO . The solvent was removed in vacuo and

A

2

4

the crude product was puriﬁed by column chromatography

and recrystallization.

aAbbreviations: K=crystalline solid, N=nematic phase, S =smectic

A

phase, S =smectic

C

phase, Col =rectangular columnar

C

r

mesophase, Iso=isotropic liquid.

5-[2,5-Bis(4-ethoxyphenyl)phenyl]-4-oxapentane-1,2-diol

1a. Synthesized from 36 and 4-ethoxyphenylboronic acid.

Crystallized from light petroleum (60–80 °C). Yield: 46%;

transitions/°C: K 124 (N 58) Iso; elemental analysis (%):

60%; mp 89 °C; d (200 MHz, acetone, J/Hz) 4.69 (s, 2H,

H

PhCH Br), 7.45 (dd, J 8.5, 2.4, 1H, H-Ar), 7.60 (d, J 8.5, 1H,

2

H-Ar), 7.82 (d, J 2.4, 1H, H-Ar). The 2,5-dibromobenzyl

found (calc. for C H O ): C, 73.82 (73.91); H, 7.29 (7.16);

26 30 5

bromide obtained in this way was used without further puriﬁ-

cation for the next step.

d (200 MHz, CDCl , J/Hz) 1.43 (2t, J 6.9, 6H, CH ), 1.76

H

3

(s, broad, 2H, OH), 3.4–3.7 (m, 4H, OCH ), 3.75–3.9 [m, 1H,

2

CH(OH)], 4.06 (t, J 6.8, 2H, PhOCH ), 4.09 (t, J 7.0, 2H,

2

In a two-necked ﬂask equipped with a reﬂux condenser and

a magnetic stirring bar, Bu NHSO (30 mg) was added to a

PhOCH ), 4.49 (s, 2H, PhCH O), 6.93 (d, J 8.5, 2H, H-Ar),

4

2

mixture consisting of 4-hydroxymethyl-2,2-dimethyl-1,3-

dioxolane (0.1 mol, 13.2 g), 2,5-dibromobenzyl bromide

(0.01 mol, 3.3 g) and 50% aq. NaOH (15 ml) under argon

atmosphere. The mixture was stirred rapidly at 60 °C for 15 h.

After cooling 50 ml water and 50 ml diethyl ether were added.

The organic phase was separated and the aqueous phase was

extracted three times with diethyl ether (100 ml). The com-

bined organic phases were dried with Na SO and afterwards,

6.98 (d, J 8.6, 2H, H-Ar), 7.3–7.35 (m, 3H, H-Ar), 7.5–7.6

(m, 3H, H-Ar), 7.63 (d, J 1.8, 1H, H-Ar); m/z (%) 422

([M]+, 100).

5-[2,5-Bis(4-hexyloxyphenyl)phenyl]-4-oxapentane-1,2-diol

1b. Synthesized from 36 and 4-hexyloxyphenylboronic acid.

Crystallized from n-hexane. Yield: 44%; transitions/°C: K 80

(S 71) Iso; elemental analysis (%): found (calc. for C H O ):

2

4

A

34 46 5

3

the solvent was removed in vacuo. The residue was puriﬁed by

column chromatography (silica gel, chloroform). Yield: 42%;

yellow oil; d (500 MHz, CDCl , J/Hz) 1.37 (s, 3H, CH ),

C, 75.73 (76.37); H, 8.83 (8.67); d (200 MHz, CDCl , J/Hz)

H

0.91 (t, J 6.3, 6H, CH ), 1.21–1.58 (m, 12H, CH ), 1.69–1.88

(m, 4H, OCH CH ), 1.95 (dd, 1H, CH OH), 2.42 [d, 1H,

CH(OH)], 3.45–3.68 (m, 4H, OCH ), 3.74–3.86 [m, 1H,

CH(OH)], 3.99 (t, J 6.2, 4H, PhOCH ), 4.49 (s, 2H, PhCH O),

6.91 (d, J 8.5, 2H, H-Ar), 6.96 (d, J 8.6, 2H, H-Ar), 7.29 (d,

J 8.5, 2H, H-Ar), 7.31 (d, J 8.3, 1H, H-Ar), 7.49–7.59 (m,

3H, H-Ar), 7.62 (d, J 1.8, 1H, H-Ar); m/z (%) 534 ([M]+, 100).

3

2

H

3

B

2

1.43 (s, 3H, CH ), 3.57 (dd, J 10.0, 5.1, 1H, PhCH OCH H ),

3

2

A

2

3.64 (dd, J 10.0, 5.6, 1H, PhCH OCH H ), 3.78 (dd, J 8.3,

6.3, 1H, OCH H ), 4.08 (dd, J 8.3, 6.4, 1H, OCH H ),

4.31–4.35 (m, 1H, CHO), 4.57 (m, 2H, PhCH O), 7.25 (dd, J

8.3, 2.4, 1H, H-Ar), 7.36 (d, J 8.3, 1H, H-Ar), 7.62 (d, J 2.4,

2

A

B

2

A

B

A B

2

1H, H-Ar).

5-[2,5-Bis(4-octyloxyphenyl)phenyl]-4-oxapentane-1,2-diol

1c. Synthesized from 36 (1 mmol, 380 mg) and 4-octyloxyphen-

ylboronic acid (2.4 mmol, 600 mg). Crystallized from light

petroleum (60–80 °C) and afterwards from methanol. Yield:

3.2.3. General procedure for the Pd-catalyzed cross-coupling

reactions. In a two-necked ﬂask equipped with a reﬂux con-

denser and a magnetic stirring bar, Pd(PPh ) (0.03 mmol,

3 4

35 mg, 3 mol%) was added under an argon atmosphere to a

35%; transitions/°C: K 79 S 102 Iso; elemental analysis (%):

A

mixture consisting of the appropriate dibromobenzene deriva-

tive (1 mmol), the boronic acid (2.4 mmol), benzene (30 ml),

ethanol (30 ml) and 2  Na CO solution (30 ml). The mixture

found (calc. for C H O ): C, 77.19 (77.25); H, 9.03 (9.21);

38 54 5

d (200 MHz, CDCl , J/Hz) 0.88 (t, J 6.6, 6H, CH ), 1.29–1.37

(m, 16H, CH ), 1.43–1.48 (m, 4H, OCH CH CH ), 1.76–1.83

(m, 4H, OCH CH ), 3.48–3.68 (m, 4H, OCH ), 3.80–3.89 [m,

1H, CH(OH)], 3.99 (t, J 6.5, 4H, PhOCH ), 4.50 (s, 2H,

H

3

2

3

2

was stirred at reﬂux temperature for 4 h. After cooling the

solvent was evaporated and the residue dissolved in diethyl

ether (30 ml) and water (30 ml). The organic phase was

2

PhCH O), 6.93–6.98 (m, 4H, H-Ar), 7.28 (d, J 8.4, 2H, H-

2

J. Mater. Chem., 1998, 8, 2611–2626

2615

Ar), 7.31 (d, J 8.0, 1H, H-Ar), 7.51–7.53 (m, 1H, H-Ar), 7.54

(d, J 8.6, 2H, H-Ar), 7.64 (d, J 1.6, 1H, H-Ar).

J 8.2, 1H, H-Ar), 7.47–7.56 (m, 3H, H-Ar), 7.63 (d, J 1.8,

1H, H-Ar); m/z (%) 758 ([M]+, 100).

5-[2,5-Bis(4-nonyloxyphenyl)phenyl]-4-oxapentane-1,2-diol

1d. Synthesized from 36 (1 mmol, 380 mg) and 4-nonyloxy-

phenylboronic acid (2.4 mmol, 632 mg). Crystallized from

light petroleum (60–80 °C). Yield: 32%; transitions/°C: K 82

S 106 Iso; elemental analysis (%): found (calc. for C H O ):

5-[2,5-Bis(4-propylphenyl)phenyl]-4-oxapentane-1,2-diol

3a. Synthesized from 36 and 4-propylphenylboronic acid.

Crystallized from n-hexane. Yield: 37%; mp 60 °C; elemental

analysis (%): found (calc. for C H O ): C, 79.72 (80.35); H,

28 34 3

7.96 (8.19); d (200 MHz, CDCl , J/Hz) 0.97 (t, J 7.2, 3H,

A

40 58 5

H

3

C, 77.56 (77.63); H, 9.53 (9.45); d (200 MHz, CDCl , J/Hz)

CH ), 0.98 (t, J 7.2, 3H, CH ), 1.59–1.78 (m, 4H, CH ), 2.62

H

3

2

0.86 (t, J 6.4, 6H, CH ), 1.27–1.34 (m, 20H, CH ), 1.42–1.47

(t, J 7.5, 4H, PhCH ), 3.4–3.7 (m, 4H, CH O), 3.7–3.9 [m,

3

2

(m, 4H, OCH CH CH ), 1.75–1.82 (m, 4H, OCH CH ),

3.44–3.67 (m, 4H, OCH ), 3.80–3.85 [m, 1H, CH(OH)], 3.98

(t, J 6.6, 4H, PhOCH ), 4.50 (s, 2H, PhCH O), 6.92–6.97 (m,

4H, H-Ar), 7.26–7.31 (m, 3H, H-Ar), 7.49–7.54 (m, 3H,

1H, CH(OH)], 4.52 (s, 2H, PhCH O), 7.20–7.31 (m, 7H, H-

2

Ar), 7.52–7.59 (m, 3H, H-Ar), 7.62 (d, J 2.0, 1H, H-Ar); m/z

(%) 418 ([M]+, 100).

2

H-Ar), 7.63 (d, J 2.0, 1H, H-Ar).

5-[2,5-Bis(4-undecylphenyl)phenyl]-4-oxapentane-1,2-diol

3b. Synthesized from 36 and 4-undecylphenylboronic acid.

Crystallized from n-hexane. Yield: 46%; transitions/°C: K 63

5-[2,5-Bis(4-decyloxyphenyl)phenyl]-4-oxapentane-1,2-diol

1e. Synthesized from 36 and 4-decyloxyphenylboronic acid.

Crystallized from n-hexane. Yield: 54%; transitions/°C: K 83

S 114 Iso; elemental analysis (%): found (calc. for C H O ):

S

78 Iso; elemental analysis (%): found (calc. for C H O ):

44 66 3

C, 81.98 (82.19); H, 10.52 (10.35); d (250 MHz, CDCl ,

A

H

3

J/Hz) 0.71 (t, J 6.5, 6H, CH ), 1.0–1.3 (m, 32H, CH ), 1.5–1.6

(m, 4H, CH ), 1.73 (dd, J 4.0, 1H, CH OH), 2.34 [d, J 5.0,

1H, CH(OH)], 2.47 (t, J 6.4, 4H, PhCH ), 3.3–3.6 (m, 4H,

OCH ), 3.6–3.7 [m, 1H, CH(OH)], 4.37 (s, 2H, PhCH O),

A

42 62 5

3

2

C, 77.74 (77.98); H, 9.85 (9.66); d (200 MHz, CDCl , J/Hz)

H

2

0.87 (t, J 6.5, 6H, CH ), 1.18–1.58 (m, 28H, CH ), 1.71–1.89

3

2

(m, 4H, OCH CH ), 3.43–3.72 (m, 4H, OCH ), 3.77–3.91 [m,

2

1H, CH(OH)], 3.99 (t, J 6.5, 4H, PhOCH ), 4.50 (s, 2H,

7.1–7.45 (m, 10H, H-Ar), 7.51 (d, J 1.4, 1H, H-Ar).

2

PhCH O), 6.92 (d, J 8.6, 2H, H-Ar), 6.96 (d, J 8.7, 2H, H-

2

Ar), 7.29 (d, J 8.5, 2H, H-Ar), 7.33 (d, J 8.2, 1H, H-Ar),

3.3. 5-{2,5-Bis[4-[4-decyloxyphenyl)phenyl]phenyl}-4-

oxapentane-1,2-diol 5

7.4–4.5 (m, 1H, H-Ar), 7.55 (d, J 8.8, 2H, H-Ar), 7.64 (d, J

1.8, 1H, H-Ar); d (125 MHz, CDCl ) 14.09 (CH ), 22.67,

C

3

26.08, 26.10, 29.32, 29.41, 29.56, 29.60, 31.91 (CH ), 64.08

Synthesized from 36 (1 mmol, 380 mg) and 4-(4-decyloxyphen-

yl)phenylboronic acid (2.4 mmol, 850 mg) according to pro-

cedures 3.2.3 and 3.2.4. Crystallized from n-hexane–ethyl

2

(CH OH), 68.15 (PhOCH ), 68.17 (PhOCH ), 70.53

2

[OCH CH(OH)], 71.80 [OCH CH(OH)], 72.03 (PhCH O),

2

114.26, 114.90, 126.19, 127.60, 128.05, 130.16, 130.68, 132.67,

132.92, 135.22, 139.81, 140.14, 158.57, 158.89 (C-Ar); m/z (%)

646 ([M]+, 100).

acetate. Yield: 43%; transitions/°C: K 152 S 258 Iso; elemental

A

analysis (%): found (calc. for C H O ): C, 80.92 (81.16); H,

54 70 5

8.98 (8.83); d (200 MHz, CDCl , J/Hz) 0.88 (t, J 6.4, 6H,

H

3

CH ), 1.2–1.6 (m, 28H, CH ), 1.7–1.9 (m, 4H, OCH CH ),

3

2

1.94 (dd, J 4.0, 1H, CH OH), 2.43 [d, J 5.0, 1H, CH(OH)],

3.5–3.77 (m, 4H, OCH ), 3.8–3.95 [m, 1H, CH(OH)], 4.00 (t,

J 6.5, 4H, PhOCH ), 4.57 (s, 2H, PhCH O), 6.98 (d, J 8.8,

4H, H-Ar), 7.4–7.7 (m, 14H, H-Ar), 7.76 (d, J 1.7, 1H, H-Ar);

m/z (%) 798 ([M]+, 100).

5-[2,5-Bis(4-undecyloxyphenyl)phenyl]-4-oxapentane-1,2-

diol 1f. Synthesized from 36 (1 mmol, 380 mg) and 4-undecyl-

oxyphenylboronic acid (2.4 mmol, 701 mg). Crystallized from

light petroleum (60–80 °C). Yield: 39%; transitions/°C: K 89

S 114 Iso; elemental analysis (%): found (calc. for C H O ):

2

A

44 66 5

3

C, 78.46 (78.24); H, 9.63 (9.86); d (200 MHz, CDCl , J/Hz)

H

0.86 (t, J 6.5, 6H, CH ), 1.26–1.46 (m, 32H, CH ), 1.76–1.83

3.4. Synthesis of the diols (S)-1e, 4, 6, 7, 11, 13, 29b,c, 31,

34b,c, 35a,b

3

2

(m, 4H, OCH CH ), 3.43–3.71 (m, 4H, OCH ), 3.79–3.86 [m,

2

1H, CH(OH)], 3.99 (t, J 6.5, 4H, PhOCH ), 4.50 (s, 2H,

2

PhCH O), 6.94 (d, J 8.6, 2H, H-Ar), 6.96 (d, J 8.8, 2H, H-

2

3.4.1. General procedure for the synthesis of benzyl ethers.

In a two-necked ﬂask equipped with a reﬂux condenser and a

magnetic stirring bar, Bu NHSO (5 mg) and 50% aq. NaOH

Ar), 7.26–7.33 (m, 3H, H-Ar), 7.49–7.56 (m, 3H, H-Ar), 7.63

(d, J 2.0, 1H, H-Ar).

4

(3 ml) were added to a solution of the alcohol (15 mmol) and

the benzyl bromide (1.5 mmol) in 10 ml toluene under argon

atmosphere. The mixture was stirred violently at 60 °C for

15 h. After cooling 30 ml water and 30 ml diethyl ether were

added. The organic phase was separated and the aqueous

phase was extracted with diethyl ether. The combined organic

phases were dried with Na SO and afterwards the solvent

5-[2,5-Bis(4-dodecyloxyphenyl)phenyl]-4-oxapentane-1,2-

diol 1g. Synthesized from 36 and 4-dodecyloxyphenylboronic

acid. Crystallized ﬁrst from light petroleum (60–80 °C) and

afterwards from methanol. Yield: 47%; transitions/°C: K 86

S

116 Iso; d (200 MHz, CDCl , J/Hz) 0.87 (t, J 6.6, 6H,

A

H

3

CH ), 1.27–1.55 (m, 36H, CH ), 1.77–1.84 (m, 4H,

OCH CH ), 1.99 (br s, 2H, OH), 3.42–3.75 (m, 4H, OCH ),

2

4

3

2

was removed in vacuo. The residue was puriﬁed by column

2

chromatography.

3.76–3.94 [m, 1H, CH(OH)], 3.99 (t, J 6.6, 4H, PhOCH ),

2

4.50 (s, 2H, PhCH O), 6.9–7.0 (m, 4H, H-Ar), 7.27–7.39 (m,

2

3.4.2. Deprotection of the 1,2-diol group. The 2,2-dimethyl-

1,3-dioxolane derivatives obtained were used, without further

puriﬁcation, for deprotection as described in 3.2.4.

3H, H-Ar), 7.5–7.7 (m, 4H, H-Ar); m/z (%) 702 ([M]+, 100).

5-[2,5-Bis(4-tetradecyloxyphenyl)phenyl]-4-oxapentane-

1,2-diol 1h. Synthesized from 36 and 4-tetradecyloxyphenyl-

boronic acid. Crystallized from ethanol. Yield: 48%;

(S)-5-[2,5-Bis(4-decyloxyphenyl)phenyl]-4-oxapentane-1,2-

diol (S)-1e. Synthesized from (R)-(−)-4-hydroxymethyl-2,2-

dimethyl-1,3-dioxolane and 37. Eluent: chloroform–methanol

(1051). Crystallized from n-hexane. Yield: 28%; transitions/°C:

transitions/°C: K 95 S 118 Iso; elemental analysis (%): found

A

(calc. for C H O ): C, 78.82 (79.09); H, 10.35 (10.36);

50 78 5

d (200 MHz, CDCl , J/Hz) 0.87 (t, J 6.4, 6H, CH ), 1.1–1.6

(m, 42H, CH ), 1.7–1.9 (m, 4H, OCH CH ), 3.37–3.73 (m,

4H, OCH ), 3.78–3.91 [m, 1H, CH(OH)], 3.99 (t, J 6.3, 4H,

PhOCH ), 4.50 (s, 2H, PhCH O), 6.93 (d, J 8.4, 2H, H-Ar),

H

3

K 83 S 114 Iso; elemental analysis (%): found (calc. for

2

A

C H O ): C, 77.86 (77.96); H, 9.70 (9.67); [a] 25+1.9,

2

42 62 5

589

[a] 25+4.9 (c 1.0, CHCl ); all other analytical data

436

correspond to those given for rac-1e.

2

3

6.96 (d, J 8.6, 2H, H-Ar), 7.29 (d, J 8.3, 2H, H-Ar), 7.31 (d,

2616 J. Mater. Chem., 1998, 8, 2611–2626

5-[3,5-Bis(4-decyloxyphenyl)phenyl]-4-oxapentane-1,2-diol

4. Synthesized from 4-hydroxymethyl-2,2-dimethyl-1,3-dioxol-

ane and 3,5-bis(4-decyloxyphenyl)benzyl bromide.20 Eluent:

chloroform–methanol (1051). Crystallized from n-hexane–

ethyl acetate. Yield: 43%; mp 67 °C; elemental analysis (%):

113.90, 114.84, 115.12, 126.37, 128.01, 129.60, 131.21, 132.94,

133.87, 136.13, 138.87, 139.43, 158.61, 158.83 (C-Ar); m/z (%)

646 ([M]+, 100).

5-{2-Decyloxy-5-[4-(4-decyloxyphenyl)phenyl]phenyl}-4-

oxapentane-1,2-diol 13. Synthesized from 4-hydroxymethyl-

2,2-dimethyl-1,3-dioxolane and 40. Eluent: chloroform–meth-

anol (1051). Crystallized from n-hexane. Yield: 21%;

found (calc. for C H O ): C, 77.88 (77.98); H, 9.78 (9.66);

42 62 5

d (500 MHz, CDCl , J/Hz) 0.87 (t, J 6.5, 6H, CH ), 1.2–1.5

H

3

(m, 28H, CH ), 1.7–1.8 (m, 4H, OCH CH ), 2.06 (br s, 1H,

2

CH OH), 2.59 [br s, 1H, CH(OH)], 3.58–3.68 (m, 3H,

transitions/°C: K 75 S 144 Iso; elemental analysis (%): found

2

A

CH OH, OCH H ), 3.72 (dd, J 11.3, 3.8, 1H, OCH H ),

(calc. for C H O ): C, 77.69 (77.98); H, 9.82 (9.66);

2

A

B

A B

42 62 5

3.92 [m, 1H, CH(OH)], 3.99 (t, J 6.5, 4H, PhOCH ), 4.64 (s,

d (500 MHz, CDCl , J/Hz) 0.88 (t, J 6.5, 6H, CH ), 1.2–1.4

(m, 24H, CH ), 1.4–1.5 (m, 4H, OCH CH CH ), 1.75–1.85

(m, 4H, OCH CH ), 2.14 (br s, 1H, CH OH), 2.72 [br s, 1H,

2

2H, PhCH O), 6.96 (d, J 8.6, 4H, H-Ar), 7.41 (d, J 1.6, 2H,

2

H

3

2

H-Ar), 7.53 (d, J 8.7, 4H, H-Ar), 7.64 (d, J 1.6, 1H, H-Ar);

2

m/z (%) 646 ([M]+, 100).

CH(OH)], 3.6–3.8 (m, 4H, OCH ), 3.88–3.95 [m, 1H,

2

CH(OH)], 3.99 (t, J 6.6, 2H, PhOCH ), 4.02 (t, J 6.6, 2H,

2

5-[5-Decyloxy-2-(4-decyloxyphenyl)phenyl]-4-oxapentane-

1,2-diol 6. Synthesized from 4-hydroxymethyl-2,2-dimethyl-

1,3-dioxolane and 5-decyloxy-2-(4-decyloxyphenyl)benzylbro-

mide.18 Eluent: chloroform–methanol (1050.5). Crystallized

PhOCH ), 4.62 (d, J 12.0, 1H, PhCH H O), 4.66 (d, J 12.0,

2

A B

2H, PhCH H O), 6.93 (d, J 8.5, 1H, H-Ar) 6.96 (d, J 8.7,

2H, H-Ar), 7.2–7.6 (m, 3H, H-Ar), 7.59 (s, 5H, H-Ar);

A

B

d (125 MHz, CDCl ) 14.07 (CH ), 22.66, 26.07, 26.11, 29.27,

C

3

from methanol. Yield: 20%; transitions/°C: K 43 (S 28) Iso;

29.31, 29.38, 29.41, 29.58, 29.60, 31.90, (CH ), 64.27

A

elemental analysis (%): found (calc. for C H O ): C, 75.58

36 58 5

2

(CH OH), 68.18 (PhOCH ), 68.42 (PhOCH ), 68.95

[OCH CH(OH)], 70.50 [OCH CH(OH)], 72.26 (PhCH O),

111.77, 114.89, 126.52, 126.99, 127.45, 127.93, 127.97, 133.04,

133.08, 138.95, 139.30, 156.49, 158.80 (C-Ar); m/z (%) 646

([M]+, 100).

2

(75.75); H, 10.37 (10.24); d (500 MHz, CDCl , J/Hz) 0.86

H

3

2

(t, J 6.5, 6H, CH ), 1.2–1.4 (m, 24H, CH ), 1.4–1.5 (m, 4H,

3

2

OCH CH CH ), 1.7–1.8 [m, 4H, OCH CH ), 1.96 (dd, J 6.0,

6.0, 1H, CH OH), 2.43 [d, J 5.1 1H, CH(OH)], 3.43 (dd, J

9.6, 6.2, 1H, OCH H ), 3.48 (dd, J 9.5, 3.9 1H, OCH H ),

3.54–3.6 (m, 1H, CH H OH), 3.62–3.69 (m, 1H, CH H OH),

3.78–3.85 [m, 1H, CH(OH)], 3.96 (t, J 6.5, 2H, PhOCH ),

3.97 (t, J 6.5, 2H, PhOCH ), 4.41 (s, 2H, PhCH O), 6.86 (dd,

J 8.6, 2.7, 1H, H-Ar), 6.91 (d, J 8.8, 2H, H-Ar), 6.99 (d, J

2.4, 1H, H-Ar), 7.16 (d, J 8.6, 1H, H-Ar), 7.19 (d, J 8.8, 2H,

H-Ar); d (125 MHz, CDCl ) 14.08 (CH ), 22.67, 26.10, 29.32,

29.35, 29.42, 29.56, 29.59, 31.90 (CH ), 64.10 (CH OH), 68.14

(PhOCH ), 68.16 (PhOCH ), 70.51 [OCH CH(OH)], 71.68

[OCH CH(OH)], 71.99 (PhCH O), 113.87, 114.18, 114.45,

115.03, 130.24, 131.23, 132.77, 134.0, 136.18, 158.30, 158.39

2

A

B

A B

11-[2,5-Bis(4-decyloxyphenyl)phenyl]-4,7,10-

A

B

trioxaundecane-1,2-diol 29b. Synthesized from 4-(7-hydroxy-

2,5-dioxaheptyl)-2,2-dimethyl-1,3-dioxolane and 37. Eluent:

chloroform–methanol (1050.3). Yield: 17%; transitions/°C: K

54 (Col 40 S 48) Iso; elemental analysis (%): found (calc.

2

r

A

for C H O ): C, 75.04 (75.16); H, 9.86 (9.60); d (200 MHz,

46 70 7

CDCl , J/Hz) 0.87 (t, J 6.7, 6H, CH ), 1.17–1.55 (m, 28H,

C

3

H

2

3

CH ), 1.7–1.9 (m, 4H, OCH CH ), 2.3 (br s, 2H, OH),

3.45–3.66 (m, 12H, OCH ), 3.74–3.82 [m 1H, CH(OH)], 3.98

(t, J 6.5, 4H, PhOCH ), 4.48 (s, 2H, PhCH O), 6.92 (d, J 8.7,

2H, H-Ar), 6.96 (d, J 8.7, 2H, H-Ar), 7.29 (d, J 8.0, 2H, H-

Ar), 7.31 (d, 1H, J 8.7, H-Ar), 7.50 (dd, J 8.0, 2.0, 1H, H-

Ar), 7.57 (d, J 8.8, 2H, H-Ar), 7.72 (d, J 1.8, 1H, H-Ar);

d (125 MHz, CDCl ) 14.07 (CH ), 22.65, 26.07, 26.09, 29.30,

29.32, 29.34, 29.41, 29.55, 29.57, 30.84, 31.88, (CH ), 63.91

(CH OH), 68.11 (PhOCH ), 68.15 (PhOCH ), 69.62, 70.49,

2

(C-Ar); m/z (%) 570 ([M]+, 100).

5-(2,5-Didecyloxphenyl)-4-oxapentane-1,2-diol 7.

Synthesized from 4-hydroxymethyl-2,2-dimethyl-1,3-dioxolane

and 2,5-didecyloxybenzyl bromide.18 Eluent: chloroform–

methanol (1050.5). Crystallized from n-pentane. Yield: 34%;

C

3

2

mp 42 °C; elemental analysis (%): found (calc. for C H O ):

70.53, 70.57, 70.81, [OCH CH(OH), OCH ], 71.28

[OCH CH(OH)], 73.00 (PhCH O), 114.16, 114.82, 125.85,

127.53, 128.05, 130.34, 130.46, 132.72, 133.12, 135.60, 139.63,

30 54 5

2

C, 72.65 (72.83); H, 11.34 (11.00); d (200 MHz, CDCl ,

H

3

2

J/Hz) 0.85 (t, J 6.4, 6H, CH ), 1.1–1.5 (m, 28H, CH ), 1.7–1.8

3

2

(m, 4H, OCH CH ), 2.18 (br s, 1H, CH OH), 2.76 [br s, 1H,

139.99, 158.46, 158.79 (C-Ar); m/z (%) 734 ([M]+, 100).

14-[2,5-Bis(4-decyloxyphenyl)phenyl]-4,7,10,13-

2

CH(OH)], 3.5–3.7 [m, 5H, OCH , CH(OH)], 3.87 (t, J 6.5,

2H, PhOCH ), 3.89 (t, J 6.6, 2H, PhOCH ), 4.50 (d, J 11.9,

1H, PhCH H O), 4.57 (d, J 12.1, 1H, PhCH H O), 6.75 (s,

1H, H-Ar), 6.76 (s, 1H, H-Ar), 6.87 (s, 1H, H-Ar); m/z (%)

494 ([M]+, 100).

2

tetraoxatetradecane-1,2-diol 29c. Synthesized from 4-(10-

A

B

A B

hydroxy-2,5,8-trioxadecyl)-2,2-dimethyl-1,3-dioxolane

and

37. Eluent: chloroform–methanol (1050.3). Yield: 16%;

transitions/°C: K 45 (Col 40) Iso; elemental analysis (%):

r

5-{5-Decyloxy-2-[4-(4-decyloxyphenyl)phenyl]phenyl}-4-

oxapentane-1,2-diol 11. Synthesized from 4-hydroxymethyl-

2,2-dimethyl-1,3-dioxolane and 39. Eluent: chloroform–meth-

anol (1050.5). Crystallized from n-hexane. Yield: 23%;

found (calc. for C H O ): C, 73.56 (74.00); H, 9.53 (9.57);

48 74 8

d (200 MHz, CDCl , J/Hz) 0.87 (t, J 6.7, 6H, CH ), 1.27–1.45

(m, 28H, CH ), 1.76–1.83 (m, 4H, OCH CH ), 3.50–3.62 (m,

16H, OCH ), 3.71–3.87 [m, 1H, CH(OH)], 3.98 (t, J 6.5, 4H,

PhOCH ), 4.49 (s, 2H, PhCH O), 6.93 (d, J 8.5, 2H, H-Ar),

6.96 (d, J 8.6, 2H, H-Ar), 7.26–7.33 (m, 3H, H-Ar), 7.49 (dd,

J 8.7, 1.7, 1H, H-Ar), 7.55 (d, J 8.7, 2H, H-Ar), 7.71 (d, J

1.7, 1H, H-Ar); m/z (%) 778 ([M]+, 100).

H

3

2

transitions/°C: K 86 S 114 Iso; elemental analysis (%): found

A

2

(calc. for C H O ): C, 77.83 (77.98); H, 9.79 (9.66); d

42 62 5

H

(200 MHz, CDCl , J/Hz) 0.88 (t, J 6.5, 6H, CH ), 1.2–1.6

(m, 28H, CH ), 1.75–1.84 (m, 4H, OCH CH ), 1.92 (dd, J

6.0, 6.0, 1H, CH OH), 2.41 [d, J 5.1, 1H, CH(OH)], 3.44–3.52

(m, 2H, OCH ), 3.55–3.60 (m, 1H, CH H OH), 3.62–3.68

(m, 1H, CH H OH), 3.79–3.85 [m, 1H, CH(OH)], 3.98 (t, J

6.5, 2H, PhOCH ), 3.99 (t, J 6.5, 2H, PhOCH ), 4.47 (s, 2H,

PhCH O), 6.89 (dd, J 8.6, 2.6, 1H, H-Ar), 6.96 (d, J 8.8,

2H, H-Ar), 7.08 (d, J 2.4, 1H, H-Ar), 7.22 (d, J 8.8, 1H, H-

3

2

13-[2,5-Bis(4-decyloxyphenyl)phenyl]-12-oxatridecane-1,2-

diol 31. Synthesized from 4-(9-hydroxynonyl)-2,2-dimethyl-

1,3-dioxolane and 37. Eluent: chloroform–methanol (1051).

Crystallized from n-hexane. Yield: 21%; transitions/°C: K 54

2

A B

A

B

2

(N 30) Iso; elemental analysis (%): found (calc. for C H O ):

50 78 5

Ar), 7.34 (d, J 8.1, 2H, H-Ar), 7.52–7.59 (2d, 4H, H-Ar);

d (50 MHz, CDCl ) 14.09 (CH ), 22.65, 26.05, 29.30, 29.39,

C, 78.86 (79.11); H, 10.74 (10.36); d (200 MHz, CDCl ,

H

3

J/Hz) 0.88 (t, J 6.5, 6H, CH ), 1.24–1.4 (m, 34H, CH ),

C

3

2

29.55, 31.87 (CH ), 64.02 (CH OH), 68.10 (PhOCH ), 70.47

1.4–1.62 (m, 8H, CH ), 1.77–1.85 (m, 6H, OCH CH ), 3.43

2

[OCH CH(OH)], 71.64 [OCH CH(OH)], 71.99 (PhCH O),

(t, J 6.5, 2H, PhCH OCH ), 3.38–3.46 [m, 1H, CH H OH],

2

A B

J. Mater. Chem., 1998, 8, 2611–2626

2617

3.61–3.73, [m, 2H, CH H OH, CH(OH)], 4.02 (t, J 6.5, 2H,

7.31 (d, J 8.6, 1H, H-Ar), 7.52 (dd, J 8.1, 1.7, 1H, H-Ar), 7.55

(d, J 8.7, 2H, H-Ar), 7.72 (d, J 1.7, 1H, H-Ar); m/z (%) 704

([M]+, 67), 556 (59).

A

B

PhOCH ), 4.04 (t, J 6.5, 2H, PhOCH ), 4.42 (s, 2H, PhCH O),

2

6.94 (d, J 8.5, 2H, H-Ar), 6.97 (d, J 8.6, 2H, H-Ar), 7.29–7.35

(m, 3H, H-Ar), 7.50 (dd, J 8.7, 1.7, 1H, H-Ar), 7.56 (d, J 8.7,

2H, H-Ar), 7.71 (d, J 1.8, 1H, H-Ar); m/z (%) 758 ([M]+, 100).

14-[2,5-Bis(4-decyloxyphenyl)phenyl]-4,7,10,13-

tetraoxatetradecanol 30b. Synthesized from tetraethylene glycol

11-{2-Decyloxy-5-[4-(4-decyloxyphenyl)phenyl]phenyl}-

4,7,10-trioxaundecane-1,2-diol 34b. Synthesized from 4-(7-

hydroxy-2,5-dioxaheptyl)-2,2-dimethyl-1,3-dioxolane and 40.

Eluent: chloroform–methanol (1050.5). Yield: 32%;

transitions/°C: K 36 S 97 Iso; d (400 MHz, CDCl , J/Hz)

and 37. Eluent: chloroform–methanol (1050.5). Crystallized

from n-hexane. Yield: 25%; transitions/°C: K 44 (S 31) Iso;

A

elemental analysis (%): found (calc. for C H O ): C, 75.08

47 72 7

(75.36); H, 9.76 (9.69); d (200 MHz, CDCl , J/Hz) 0.91 (t, J

H

3

A

3

2

H

3

6.4, 6H, CH ), 1.2–1.6 (m, 28H, CH ), 1.75–1.92 (m, 4H,

0.87 (t, J 6.4, 6H, CH ), 1.27–1.36 (m, 24H, CH ), 1.42–1.49

3

2

OCH CH ), 3.54–3.78 (m, 16H, OCH ), 4.01 (t, J 6.5, 4H,

PhOCH ), 4.52 (s, 2H, PhCH O), 6.93 (d, J 8.5, 2H, H-Ar),

6.96 (d, J 8.6, 2H, H-Ar), 7.28 (d, J 8.5, 2H, H-Ar), 7.31 (d,

J 8.6, 1H, H-Ar), 7.5–7.6 (m, 3H, H-Ar), 7.74 (d, J 1.7, 1H,

H-Ar); m/z (%) 748 ([M]+, 68), 704 (27).

(m, 4H, OCH CH CH ), 1.75–1.83 (m, 4H, OCH CH ), 2.28

2

(br s, 2H, OH), 3.50–3.71 (m, 12H, OCH ), 3.78–3.83 [m,

2

1H, CH(OH)], 3.99 (t, J 6.6, 2H, PhOCH ), 4.00 (t, J 6.4,

2

2H, PhOCH ), 4.66 (s, 2H, PhCH O), 6.90 (d, J 8.4, 1H, H-

2

Ar), 6.96 (d, J 8.8, 2H, H-Ar), 7.48 (dd, J 8.4, 2.3, 1H, H-

Ar), 7.54 (d, J 8.6, 2H, H-Ar), 7.57–7.62 (m, 4H, H-Ar), 7.68

(d, J 2.3, 1H, H-Ar); m/z (%) 734 ([M]+, 74), 660 (79).

3.6. Synthesis of the p-terphenyl derivatives 29a and 34a

14-{2-Decyloxy-5-[4-(4-decyloxyphenyl)phenyl]phenyl}-

4,7,10,13-tetraoxatetradecane-1,2-diol 34c. Synthesized from

4-(10-hydroxy-2,5,8-trioxadecyl)-2,2-dimethyl-1,3-dioxolane

and 40. Eluent: chloroform–methanol (1050.3). Yield: 27%;

transitions/°C: K 45 S 72 Iso; d (200 MHz, CDCl , J/Hz)

At ﬁrst the appropriate bromomethyl substituted 4,4>-didecyl-

oxy-p-terphenyl derivatives 37 and 40 were etheriﬁed according

to procedure 3.4.1 with 2-allyloxyethanol to give the allyl

ether. The allyl ethers were used without further puriﬁcation

for the dihydroxylation reaction.

A

H

3

0.87 (t, J 6.4, 6H, CH ), 1.27–1.55 (m, 28H, CH ), 1.70–1.85

3

2

(m, 4H, OCH CH ), 3.5–3.7 [m, 17H, OCH , CH(OH)], 3.99

2

3.6.1. Procedure for the dihydroxylation. The appropriate

allyl ether (1 mmol, 657 mg) was added to a solution of N-

methylmorpholine N-oxide (1.4 mmol, 0.15 ml of 60% aq.

solution) in acetone (20 ml). Osmium tetroxide (0.05 ml of

0.01  solution in tert-butyl alcohol) was added and the

resulting mixture was stirred for 24 h at room temperature.

After this time starting materials could no longer be detected

and the mixture was worked up as follows: sodium hydrogen

sulﬁte (4 ml saturated solution) was added and the resulting

slurry was vigorously stirred at room temperature for 30 min.

Afterwards, the solid were ﬁltered oﬀ, the residue was extracted

three times with ethyl acetate (30 ml) and the combined

organic phases were washed with 10% H SO , water and

(t, J 6.4, 4H, PhOCH ), 4.66 (s, 2H, PhCH O), 6.90 (d, J 8.6,

2

1H, H-Ar), 6.96 (d, J 8.6, 2H, H-Ar), 7.4–7.7 (m, 8H, H-Ar);

m/z (%) 778 ([M]+, 100).

8-{2-Decyloxy-5-[4-(4-decyloxyphenyl)phenyl]phenyl}-7-

oxaoctane-1,2-diol 35a. Synthesized from 4-(4-hydroxybutyl)-

2,2-dimethyl-1,3-dioxolane and 40. Eluent: chloroform–meth-

anol (1050.2). Yield: 37%; transitions/°C: K 75 S 114 Iso;

A

3

d (200 MHz, CDCl , J/Hz) 0.88 (t, J 6.6, 6H, CH ), 1.2–1.9

H

3

(m, 38H, CH ), 3.39 (dd, J 10.8, 7.6, 1H, CH H OH), 3.5–3.7

2

A

A B

[m, 4H, CH H OH, CH(OH), CH O], 3.99 (t, J 6.6, 2H,

PhOCH ), 4.00 (t, J 6.5, 2H, PhOCH ), 4.59 (s, 2H, PhCH O),

6.90 (d, J 8.6, 1H, H-Ar), 6.96 (d, J 8.8, 2H, H-Ar), 7.47 (dd,

J 8.4, 2.4, 1H, H-Ar), 7.5–7.65 (m, 6H, H-Ar), 7.64 (d, 2.3,

1H, H-Ar); m/z (%) 688 ([M]+, 100).

B

2

4

brine. After drying with Na SO the solvent was evaporated

2

4

and the crude products were puriﬁed by column

chromatography.

13-{2-Decyloxy-5-[4-(4-decyloxyphenyl)phenyl]phenyl}-

12-oxatridecane-1,2-diol 35b. Synthesized from 4-(9-hydroxy-

nonyl)-2,2-dimethyl-1,3-dioxolane and 40. Crystallized from

light petroleum (60–80 °C). Yield: 17%; mp 110–112 °C;

8-[2,5-Bis(4-decyloxyphenyl)phenyl]-4,7-dioxaoctane-1,2-

diol 29a. Synthesized from 2-allyloxyethanol and 37, followed

by dihydroxylation. Eluent: chloroform–methanol (1050.3).

Yield: 10%; transitions/°C: K 66 S 73 Iso; d (200 MHz,

elemental analysis (%): found (calc. for C H O ): C, 78.87

50 78 5

(79.11); H, 10.53 (10.36); d (200 MHz, CDCl , J/Hz) 0.89

A

H

3

CDCl , J/Hz) 0.87 (t, J 6.7, 6H, CH ), 1.24–1.74 (m, 28H,

(t, J 6.8, 6H, CH ), 1.29–1.40 (m, 44H, CH ), 1.74–1.85 (m,

3

2

CH ), 1.76–1.83 (m, 4H, OCH CH ), 3.5–3.7 (m, 8H, OCH ),

4H, OCH CH ), 3.36–3.67 [m, 5H, CH(OH), OCH ], 4.01

2

3.7–3.9 [m, 1H, CH(OH)], 3.98 (t, J 6.5, 4H, PhOCH ), 4.49

(t, J 6.6, 2H, PhOCH ), 4.02 (t, J 6.5, 2H, PhOCH ), 4.61 (s,

2H, PhCH O), 6.92 (d, J 8.6, 1H, H-Ar), 6.98 (d, J 8.8, 2H,

H-Ar), 7.47–7.65 (m, 4H, H-Ar), 7.68 (d, 2.3, 1H, H-Ar); m/z

2

(s, 2H, PhCH O), 6.93 (d, J 8.6, 2H, H-Ar), 6.96 (d, J 8.7,

2

2H, H-Ar), 7.27–7.51 (m, 3H, H-Ar), 7.51 (d, J 8.8, 1H, H-

Ar), 7.55 (d, J 8.7, 2H, H-Ar), 7.70 (d, J 1.7, 1H, H-Ar); m/z

(%) 690 ([M]+, 100).

(%) 758 ([M]+, 18), 556 (100).

3.5. Synthesis of the oligoethylene glycol ethers 30

8-{2-Decyloxy-5-[4-(4-decyloxyphenyl)phenyl]phenyl}-4,7-

dioxaoctane-1,2-diol 34a. Synthesized from 2-allyloxyethanol

and 40, followed by dihydroxylation. Eluent: chloroform–

These compounds were obtained by etheriﬁcation of

appropriate benzyl bromides with triethylene glycol and tetra-

ethylene glycol respectively, according to procedure 3.4.1.

methanol (1050.5). Yield: 30%; transitions/°C: K 58 S 121

A

Iso; elemental analysis (%): found (calc. for C H O ): C,

44 66 6

11-[2,5-Bis(4-decyloxyphenyl)phenyl]-4,7,10-

76.20 (76.48); H, 9.89 (9.63); d (200 MHz, CDCl , J/Hz)

trioxaundecanol 30a. Synthesized from triethylene glycol and

37. Eluent: chloroform–methanol (1050.1). Yield: 18%;

transitions/°C: K 61 (S 52) Iso; d (200 MHz, CDCl , J/Hz)

H

3

0.87 (t, J 6.6, 6H, CH ), 1.2–1.6 (m, 28H, CH ), 1.7–1.9 (m,

3

2

4H, OCH CH ), 3.5–3.75 (m, 8H, OCH ), 3.8–3.9 [m, 1H,

CH(OH)], 3.98 (t, J 6.6, 2H, PhOCH ), 4.00 (t, J 6.4, 2H,

PhOCH ), 4.66 (s, 2H, PhCH O), 6.90 (d, J 8.4, 1H, H-Ar),

2

A

H

3

0.87 (t, J 6.5, 6H, CH ), 1.26–1.55 (m, 28H, CH ), 1.72–1.86

2

3

2

(m, 4H, OCH CH ), 3.53–3.69 (m, 12H, OCH ), 3.98 (t, J

6.5, 4H, PhOCH ), 4.48 (s, 2H, PhCH O), 6.93 (d, J 8.5, 2H,

H-Ar), 6.95 (d, J 8.6, 2H, H-Ar), 7.30 (d, J 8.0, 2H, H-Ar),

2

6.96 (d, J 8.8, 2H, H-Ar), 7.4–7.6 (m, 7H, H-Ar), 7.65 (d, J

2.2, 1H, H-Ar); m/z (%) 690 ([M]+, 100).

2

2618 J. Mater. Chem., 1998, 8, 2611–2626

3.7. 2,5-Bis(4-decyloxyphenyl)benzyl(triethyl)ammonium

bromide 28

the yellowish oil obtained was crystallized from n-hexane.

Yield: 92%; transitions/°C: K 58 (N 40) Iso; elemental analysis

(%): found (calc. for C H O Cl): C, 77.45 (77.39); H, 8.57

39 53 3

In a three-necked ﬂask equipped with a magnetic stirring bar

and a dropping funnel 37 (1.25 mmol, 800 mg) was dissolved

in dry acetonitrile (70 ml) at 50 °C under argon atmosphere.

Dry triethylamine (30 ml) was added dropwise while stirring.

The reaction mixture was stirred under reﬂux for 15 h. After

cooling to room temperature the solvent was evaporated and

the residue dissolved in chloroform (100 ml). The organic

phase was washed several times with water and dried with

(8.83); Cl, 5.64 (5.86); d (200 MHz, CDCl , J/Hz) 0.88 (t, J

H

3

6.5, 6H, CH ), 1.26–1.41 (m, 28H, CH ), 1.67–1.78 (m, 4H,

3

2

OCH CH ), 3.81 (t, J 6.4, 2H, PhOCH ), 4.00 (t, J 6.5, 2H,

PhOCH ), 6.87 (d, J 8.5, 2H, H-Ar), 6.92 (d, J 8.5, 2H, H-

Ar), 7.29 (d, J 8.5, 2H, H-Ar), 7.30–7.32 (m, 1H, H-Ar), 7.49

2

(dd, J 8.7, 1.7, 1H, H-Ar), 7.53 (d, J 8.6, 2H, H-Ar), 7.75 (d,

J 1.2, 1H, H-Ar).

CaCl . The solvent was removed in vacuo and the crude

product obtained was puriﬁed by column chromatography

(Silica gel, chloroform–methanol 1052) followed by recrys-

tallization from ethyl acetate. Yield: 35%; mp 140 °C; elemental

2

3.11. Synthesis of the 2,5-bis(4-decyloxyphenyl)benzamides

15–24

In a three-necked ﬂask equipped with a magnetic stirring bar

the appropriate amine (1,5 mmol) was dissolved in dry DMF

(30 ml) under argon atmosphere. A solution of 26 (0.5 mmol,

300 mg) in toluene (20 ml) was slowly added dropwise to this

stirred mixture at room temperature. The mixture was stirred

several hours at 80 °C, until the reaction was complete

(TLC). After the solvent was removed in vacuo the residue

was dissolved in diethyl ether (100 ml) and the organic phase

was washed ﬁrst with 10% hydrochloric acid (40 ml) and

afterwards with water (50 ml). The organic phase was dried

with sodium sulfate. Then the solvent was evaporated and the

crude product obtained was puriﬁed by ﬂash column

chromatography followed by recrystallization.

analysis (%): found (calc. for C H O NBr): C, 72.96 (73.34);

45 70 2

H, 9.26 (9.57); Br, 10.53 (10.84); N, 1.96 (1.90); d (200 MHz,

H

CDCl , J/Hz) 0.86 (t, J 6.6, 6H, CH ), 1.14 (t, J 6.4, 9H,

3

2

3

NCH CH ), 1.18–1.57 (m, 28H, CH ), 1.7–1.9 (m, 4H,

3

2

OCH CH CH ), 3.15–3.35 (m, 6H, NCH CH ), 3.97 (t, J 6.5,

2

3

4H, PhOCH ), 4.94 (s, 2H, PhCH N), 6.94 (d, J 8.5, 2H, H-

2

Ar), 6.99 (d, J 8.6, 2H, H-Ar), 7.21 (d, J 8.4, 2H, H-Ar), 7.35

(d, J 8.0, 1H, H-Ar), 7.56 (d, J 8.5, 2H, H-Ar), 7.65 (d, J 8.7,

1H, H-Ar), 7.87 (s, 1H, H-Ar).

3.8. Sodium 2,5-bis(4-decyloxyphenyl)benzoate 27

Methyl 2,5-bis(4-decyloxyphenyl)benzoate 14 (1 mmol,

601 mg) was added to a stirred solution prepared from ethanol

(50 ml) and NaOH (0.25 mol, 10 g) and heated 4 h under

reﬂux. After termination of the reaction the solvent was

removed in vacuo and 50 ml water were added. The aqueous

phase was extracted three times with chloroform (50 ml). The

combined organic phases were washed several times with water

and brine and afterwards dried with calcium chloride. After

evaporation of the solvent the residue was recrystallized from

ethyl acetate. Yield: 86%; mp 216–218 °C; elemental analysis

2,5-Bis(4-decyloxyphenyl)benzamide 15. Synthesized by

introduction of ammonia into a solution of 26 in DMF at

room temperature. Eluent: chloroform–methanol (1051).

Crystallized from ethyl acetate. Yield: 65%; mp 184 °C; elemen-

tal analysis (%): found (calc. for C H O N): C, 79.99 (79.95);

39 55 3

H, 9.21 (9.46); N, 2.04 (2.39); d (500 MHz, CDCl , J/Hz)

H

3

0.87 (t, J 6.7, 6H, CH ), 1.2–1.5 (m, 28H, CH ), 1.75–1.84

3

2

(m, 4H, OCH CH ), 3.97 (t, J 6.8, 2H, PhOCH ), 3.99 (t, J

6.7, 2H, PhOCH ), 5.28 (br s, 1H, NH), 5.44 (br s, 1H, NH),

6.94 (d, J 8.6, 2H, H-Ar), 6.97 (d, J 8.5, 2H, H-Ar), 7.35 (d,

2

(%): found (calc. for C H O Na): C, 77.25 (76.94); H, 8.85

2

39 53 4

(8.77); d (200 MHz, CDCl , J/Hz) 0.85 (t, J 6.4, 6H, CH ),

H

3

J 7.8, 1H, H-Ar), 7.38 (d, J 8.8, 2H, H-Ar), 7.56 (d, J 8.8,

2H, H-Ar), 7.65 (dd, J 8.1, 2.1, 1H, H-Ar), 7.96 (d, J 2.0, 1H,

H-Ar); m/z (%) 585 ([M]+, 100).

1.1–1.8 (m, 28H, CH ), 1.9–2.2 (m, 4H, OCH CH ), 3.56 (t,

2

J 6.3, 4H, PhOCH ), 6.55 (d, J 8.3, 2H, H-Ar), 6.75 (d, J 8.5,

2H, H-Ar), 7.1–7.2 (m, 3H, H-Ar), 7.4–7.5 (m, 3H, H-Ar),

2

7.91 (s, 1H, H-Ar).

2,5-Bis(4-decyloxyphenyl)benzoylaminoethane 16.

Synthesized from ethylamine and 26. Eluent: chloroform–

methanol (1050.5). Crystallized from methanol. Yield: 84%;

mp 111 °C; elemental analysis (%): found (calc. for

3.9. 2,5-Bis(4-decyloxyphenyl)benzoic acid 25

Compound 27 (10 mmol, 6.1 g) was dissolved in ethanol

(250 ml). Concentrated hydrochloric acid (100 ml) was added

while stirring and the mixture was heated under reﬂux for 2 h.

After cooling, water (250 ml) was added dropwise and the

mixture was extracted three times with diethyl ether (150 ml).

The combined organic phases were washed several times with

C H O N): C, 79.98 (80.21); H, 9.37 (9.69); N, 2.04 (2.28);

41 59 3

d (500 MHz, CDCl , J/Hz) 0.87 (t, J 7.1, 9H, CH ), 1.2–1.5

H

3

(m, 28H, CH ), 1.75–1.83 (m, 4H, OCH CH ), 3.21 (dq, 2H,

2

NHCH ), 3.96 (t, J 6.8, 2H, PhOCH ), 3.98 (t, J 6.7, 2H,

2

PhOCH ), 5.19 (t, J 5.6, 1H, NH), 6.93 (d, J 8.7, 2H, H-Ar),

aq. NaHCO solution and then with water. After drying with

6.95 (d, J 8.7, 2H, H-Ar), 7.34 (d, J 8.8, 2H, H-Ar), 7.36 (d,

3

Na SO the solvent was removed in vacuo. The crude product

J 8.7, 1H, H-Ar), 7.55 (d, J 8.7, 2H, H-Ar), 7.61 (dd, J 8.0,

2.0, 1H, H-Ar), 7.87 (d, J 1.9, 1H, H-Ar); m/z (%) 613

([M]+, 100).

2

4

was puriﬁed by recrystallization from a mixture of n-hexane

and ethyl acetate. Yield: 80%; transitions/°C: K 151 (S 125)

A

Iso; elemental analysis (%): found (calc. for C H O ): C,

39 54 4

79.67 (79.82); H, 9.46 (9.27); d (200 MHz, CDCl , J/Hz)

H

3

2,5-Bis(4-decyloxyphenyl)benzohydrazide 17. Synthesized by

adding hydrazine hydrate (100%) to a solution of 14 in n-

butanol and stirring at reﬂux temperature for 10 h. Crystallized

0.87 (t, J 6.5, 6H, CH ), 1.1–1.6 (m, 28H, CH ), 1.7–1.9 (m,

3

2

4H, OCH CH ), 3.96 (t, J 6.5, 2H, PhOCH ), 3.99 (t, J 6.4,

2H, PhOCH ), 6.90 (d, J 8.4, 2H, H-Ar), 6.96 (d, J 8.5, 2H,

H-Ar), 7.29 (d, J 8.5, 2H, H-Ar), 7.38 (d, J 8.4, 1H, H-Ar),

2

from ethanol. Yield: 83%; transitions/°C: K 98 S 131 Iso;

A

elemental analysis (%): found (calc. for C H O N ): C, 77.78

7.55 (d, J 8.7, 2H, H-Ar), 7.69 (dd, J 8.6, 1.4, 1H, H-Ar), 8.09

(d, J 1.2, 1H, H-Ar); m/z (%) 586 ([M]+, 100).

39 56 3 2

(77.96); H, 9.76 (9.39); N, 4.91 (4.66); d (500 MHz, CDCl ,

H

3

2

J/Hz) 0.87 (t, J 6.7, 6H, CH ), 1.22–1.51 (m, 28H, CH ),

1.75–1.83 (m, 4H, OCH CH ), 3.8–4.0 (br s, 2H, NH ), 3.97

(t, J 6.8, 2H, PhOCH ), 3.99 (t, J 6.7, 2H, PhOCH ), 6.53

(br s, 1H, CONH), 6.93 (d, J 8.7, 2H, H-Ar), 6.96 (d, J 8.7,

2H, H-Ar), 7.31 (d, J 8.6, 2H, H-Ar), 7.38 (d, J 8.1, 1H, H-

Ar), 7.54 (d, J 8.5, 2H, H-Ar), 7.64 (dd, J 8.1, 1.9, 1H, H-

Ar), 7.83 (d, J 2.0, 1H, H-Ar); m/z (%) 600 ([M]+, 8), 567

(26), 466 (100).

3

3.10. 2,5-Bis(4-decyloxyphenyl)benzoyl chloride 26

2

Oxalyl chloride (2.5 mmol, 460 mg) was added slowly with a

syringe to a solution of 25 (0.25 mmol, 150 mg) in dry

dichloromethane (10 ml) under argon atmosphere at room

temperature. The reaction mixture was stirred for one hour.

The solvent and excess oxalyl chloride were evaporated and

J. Mater. Chem., 1998, 8, 2611–2626

2619

2-[2,5-Bis(4-decyloxyphenyl)benzoylamino]ethanol 18.

Synthesized from 2-aminoethanol and 26. Eluent: chloroform–

methanol (1051). Crystallized from n-hexane–ethyl acetate.

elemental analysis (%): found (calc. for C H O N): C, 76.43

43 63 5

(76.63); H, 9.32 (9.42); N, 2.04 (2.08); d (500 MHz, CDCl ,

H

3

2

J/Hz) 0.87 (t, J 6.5, 6H, CH ), 1.21–1.50 (m, 28H, CH ),

3

Yield: 87%; transitions/°C: K 118 S 131 Iso; elemental

1.74–1.83 (m, 4H, OCH CH ), 2.8–3.9 (m, 8H, CH N, CH O),

3.96 (t, J 6.7, 2H, PhOCH ), 3.98 (t, J 6.7, 2H, PhOCH ),

6.92 (d, J 8.8, 2H, H-Ar), 6.95 (d, J 8.7, 2H, H-Ar), 7.39 (d,

J 8.7, 1H, H-Ar), 7.43 (d, J 8.7, 2H, H-Ar), 7.53 (d, J 8.8,

2H, H-Ar), 7.55 (d, J 1.8, 1H, H-Ar), 7.61 (dd, J 8.1, 1.8, 1H,

H-Ar); m/z (%) 674 ([M+1]+, 100).

A

analysis (%): found (calc. for C H O N): C, 77.99 (78.18);

41 59 4

2

H, 9.37 (9.44); N, 2.04 (2.22); d (500 MHz, CDCl , J/Hz)

H

3

0.87 (t, J 6.5, 6H, CH ), 1.23–1.50 (m, 28H, CH ), 1.77–1.82

3

2

(m, 4H, OCH CH ), 3.26 (dt, J 10.2, 5.5, 2H, NHCH ), 3.50

(t, J 5.1, 2H, CH OH), 3.97 (t, J 6.7, 2H, PhOCH ), 3.99 (t,

J 6.7, 2H, PhOCH ), 5.68 (t, J 6.0, 1H, NH), 6.94 (dd, J 8.8,

2.1, 2H, H-Ar), 6.96 (2d, 4H, H-Ar), 7.37 (d, J 8.7, 3H, H-

2

4-[2,5-Bis(4-decyloxyphenyl)benzoyl]morpholine 23.

Ar), 7.55 (d, J 8.0, 2H, H-Ar), 7.63 (dd, J 8.0, 2.0, 1H, H-Ar),

7.86 (d, J 2.0, 1H, H-Ar); m/z (%) 629 ([M]+, 100).

3-[2,5-Bis(4-decyloxyphenyl)benzoylamino]propane-1,2-diol

19. Synthesized from 3-aminopropane-1,2-diol and 26. Eluent:

ethyl acetate. Crystallized from n-hexane–ethyl acetate. Yield:

Synthesized from morpholine and 26. Eluent: ethyl acetate.

Crystallized from n-hexane–ethyl acetate. Yield: 81%; mp

96 °C; elemental analysis (%): found (calc. for C H O N):

43 61 4

C, 78.69 (78.74); H, 9.51 (9.37); N, 2.08 (2.14); d (500 MHz,

H

CDCl , J/Hz) 0.87 (t, J 6.5, 6H, CH ), 1.24–1.51 (m, 28H,

3

2

CH ), 1.71–1.87 (m, 4H, OCH CH ), 2.49–3.75 (m, 8H,

2

90%; transitions/°C: K 115 S 142 Iso; elemental analysis (%):

CH N, CH O), 3.99 (t, J 6.7, 4H, PhOCH ), 6.97 (2d, 4H,

A

2

found (calc. for C H O N): C, 76.19 (76.43); H, 9.21 (9.32);

H-Ar), 7.40 (d, J 8.9, 2H, H-Ar), 7.5–7.7 (m, 5H, H-Ar); m/z

(%) 655 ([M]+, 80), 429 (27).

42 61 5

N, 2.04 (2.12); d (500 MHz, CDCl , J/Hz) 0.87 (t, J 6.5, 6H,

CH ), 1.22–1.50 (m, 28H, CH ), 1.74–1.85 (m, 4H,

OCH CH ), 3.21–3.27 (m, 1H, NHCH H ), 3.32–3.37 (m,

1H, NHCH H ), 3.40 (dd, J 11,2, 4.8, 1H, CH H OH), 4.35

H

3

2

3

16-[2,5-Bis(4-decyloxyphenyl)benzoyl]-1,4,7,10,13-

2

A B

pentaoxa-16-azacyclooctadecane

24.

Synthesized

from

A

B

A B

(dd, J 11,4, 4.5, 1H, CH H OH), 3.55–3.59 [m, 1H, CH(OH)],

1,4,7,10,13-pentaoxa-16-azacyclooctadecane and 26. Eluent:

ethyl acetate. Crystallized from n-hexane. Yield: 72%; mp

A

B

3.97 (t, J 6.7, 2H, PhOCH ), 3.99 (t, J 6.7, 2H, PhOCH ),

2

5.72 (dd, J 6.0, 6.0, 1H, NH), 6.93 (d, J 8.5, 2H, H-Ar), 6.95

(d, J 8.7, 2H, H-Ar), 7.33 (d, J 8.7, 2H, H-Ar), 7.35 (d, J 8.0,

1H, H-Ar), 7.54 (d, J 8.7, 2H, H-Ar), 7.63 (dd, J 8.0, 2.0, 1H,

H-Ar), 7.86 (d, J 2.0, 1H, H-Ar); d (125 MHz, CDCl ) 14.11

73 °C; elemental analysis (%): found (calc. for C H O N):

51 77 8

C, 73.29 (73.61); H, 9.57 (9.33); N, 1.61 (1.68); d (200 MHz,

H

CDCl , J/Hz) 0.86 (t, J 6.4, 6H, CH ), 1.24–1.56 (m, 28H,

3

CH ), 1.69–1.85 (m, 4H, OCH CH ), 3.1–3.8 (m, 24H, NCH ,

C

3

2

(CH ), 22.68, 26.04, 29.24, 29.28, 29.32, 29.41, 29.56, 29.58,

31.89 (CH ), 42.70 (NHCH ), 63.63 (CH OH), 68.13

(PhOCH ), 68.23 (PhOCH ), 70.89 [CH(OH)CH OH],

114.74, 114.91, 126.97, 128.01, 128.45, 129.92, 130.78, 131.84,

134.95, 137.31, 139.94, 159.12 (C-Ar), 171.58 (CO); m/z (%)

659 ([M]+, 100).

OCH ), 3.94 (t, J 6.7, 2H, PhOCH ), 3.98 (t, J 6.7, 2H,

3

2

PhOCH ), 6.87 (d, J 8.7, 2H, H-Ar), 6.94 (d, J 8.8, 2H, H-Ar),

2

7.3–7.6 (m, 7H, H-Ar); m/z (%) 831 ([M]+, 100).

2

4. Results and discussion

4.1. Facial amphiphiles with lateral propane-2,3-diol groups

N-[2,5-Bis(4-decyloxyphenyl)benzoyl]-1-deoxy-1-

The glycerol ether 1e was the ﬁrst compound investigated.27

It exhibits an enantiotropic smectic A phase. A comparison

of the diol 1 with compound 227 carrying a lateral alkyl

substituent of comparable size (Fig. 2) indicates a signiﬁcant

mesophase stabilizing inﬂuence of the two hydroxy groups.

Furthermore, it is obvious that the laterally attached hydrogen

bonding group increases the structural order, which means

that the layered smectic A phase is stabilized with respect to

the nematic phase of the nonamphiphilic compound 2.

Contrary to smectic phases of conventional amphiphiles and

methylamino--glucitol 20. Synthesized from 1-deoxy-1-

methylamino--glucitol and 26. Eluent: chloroform–methanol

(1052). Crystallized from n-pentane. Yield: 90%; mp 87 °C;

elemental analysis (%): found (calc. for C H O N): C, 71.98

46 69 8

(72.31); H, 9.37 (9.10); N, 1.74 (1.83); [a] 30 0.9 (c 1.05,

D

CHCl ); d (500 MHz, CDCl , J/Hz) 0.86 (t, J 6.1, 6H, CH ),

3

H

3

1.21–1.48 (m, 28H, CH ), 1.71–1.82 (m, 4H, OCH CH ), 2.47

2

(s, 3H, NCH ), 3.2–4.95 [m, 8H, CH(OH), CH O, CH N],

3.94 (t, J 6.7, 2H, PhOCH ), 3.96 (t, J 6.7, 2H, PhOCH ),

6.93 (2d, 4H, H-Ar), 7.33 (d, J 8.6, 2H, H-Ar), 7.38 (d, J 8.1,

1H, H-Ar), 7.51 (d, J 8.6, 3H, H-Ar), 7.59 (dd, J 8.2, 1.8, 1H,

H-Ar); m/z (%) 763 ([M]+, 18), 599 (28), 586 (23), 569 (100).

3

2

1-[2,5-Bis(4-decyloxyphenyl)benzoylamino]-1-deoxy- -

D

glucitol 21. Synthesized from 1-amino-1-deoxy--glucitol and

26. Eluent: chloroform–methanol (1052). Crystallized from n-

hexane–ethyl acetate. Yield: 76%; transitions/°C: K 112 S

A

147 Iso; elemental analysis (%): found (calc. for C H O N):

45 67 8

C, 71.71 (72.06); H, 9.22 (9.00); N, 1.59 (1.87); [a] 25 −0.1

D

(c 1.09, CHCl ); d (200 MHz, DMSO, J/Hz) 0.87 (t, J 6.5,

3

H

6H, CH ), 1.21–1.52 (m, 28H, CH ), 1.74–1.83 (m, 4H,

3

2

OCH CH ), 3.2–3.7 [m, 8H, CH(OH), CH O, CH N], 3.98

(t, J 6.7, 2H, PhOCH ), 3.99 (t, J 6.7, 2H, PhOCH ), 4.1–4.4

2

(m, 3H, OH), 4.48 (d, J 4.7, 1H, OH), 4.77 (d, J 4.5, 1H,

OH), 6.93 (d, J 8.7, 2H, H-Ar), 6.99 (d, J 8.8, 2H, H-Ar),

7.34 (d, J 8.6, 2H, H-Ar), 7.38 (d, J 8.1, 1H, H-Ar), 7.62 (m,

4H, H-Ar), 8.19 (dd, J 5.4, 5.4, 1H, NH); m/z (%) 749 ([M]+,

68), 627 (21), 586 (83), 569 (100).

Fig. 2 Comparison of the mesomorphic properties of the laterally

substituted compounds 1e and 2.27 The existence regions of the phases

are displayed as bars. Black areas indicate the solid crystalline state

and hatched or blank areas correspond to liquid crystalline phases. If

the liquid crystalline phase appears below the melting point, these are

monotropic (metastable) mesophases which are given in brackets. The

numbers above the bars indicate the phase transition temperatures.

3-[2,5-Bis(4-decyloxyphenyl)benzoyl]-3-azapentane-1,5-diol

22. Synthesized from diethanolamine and 26. Eluent:

chloroform–methanol (1051). Crystallized from n-hexane–

Abbreviations: K=crystalline solid, N=nematic Phase, S =smectic

A

ethyl acetate. Yield: 70%; transitions/°C: K 110 (S 97) Iso;

A phase.

A

2620

J. Mater. Chem., 1998, 8, 2611–2626

amphiphiles containing terminally connected rigid units, which

usually form bilayer structures, the smectic phase of 1e presents

a monolayer structure. The ﬁxation of the molecules in the

single-layers should be provided by attractive hydrogen bond-

ing28 between their hydroxy groups and probably also by

hydrogen bonding between the hydroxy groups and the aro-

matic p-systems. Furthermore, the hydroxy groups signiﬁ-

cantly increase the polarity in the region of the rigid cores and

thus favor micro-segregation of these regions from the lipo-

philic alkyl chains.29 Thus, the smectic layer structure is

stabilized by the attractive forces provided by hydrogen

bonding and by micro-segregation.

The propane-2,3-diol group incorporates a stereogenic

center. Remarkably, however, no measurable inﬂuence of

chirality on the mesomorphic properties has been found. Both

the racemic compound 1e and the optically active compound

(S)-1e (K 83 S 114 Iso) have identical melting and clearing

A

temperatures. Therefore all other compounds described in this

paper have been prepared only as racemic mixtures.

The dependence of the mesomorphic properties on the

length of the terminal chains is shown in Fig. 3. With the

exception of the nematic ethoxy substituted compound 1a all

other synthesized p-terphenyl derivatives 1 display smectic A

phases. Remarkably, the mesophase stability signiﬁcantly

increases on elongation of the terminal lipophilic chains.

Also the quinquaphenyl derivative 5 and the biphenyl

derivative 6 exhibit S phases. The corresponding methyl

A

substituted biphenyl derivative 8, carrying the much smaller

methyl group, exhibits a monotropic nematic phase with a

signiﬁcantly lower clearing temperature than the S phase of

A

6. This again shows the stabilizing inﬂuence of the lateral diol

group. However, compound 7, incorporating only a single

benzene ring, is a non-mesomorphic compound. This shows

that the amphiphilic structure alone does not cause the liquid

crystallinity in this class of compounds. Mesomorphic proper-

ties are also lost if the linear p-terphenyl rigid core is replaced

by an angular m-terphenyl central unit (compound 4). This is

in accordance with the behavior of conventional calamitic

liquid crystals. The mesophase destabilization on replacing the

alkoxy substituents by alkyl groups (compounds 3) is also

analogous to nonamphiphilic calamitic mesogens.

4.2. Inﬂuence of the position of the diol group

In Fig. 4 the dependence of the mesomorphic properties on

the position of the 4,5-dihydroxy-2-oxapentyl group is com-

pared with the inﬂuence of a methyl group in the same

positions. For the diol derivatives 1e, 11 and 13 the order of

mesophase stability (1e~11<13) is principally the same as

for the methyl substituted molecules (915~1018<1218).

However, the S phases of the methyl substituted derivatives

C

are completely replaced by smectic A phases. Furthermore it

seems that the mesophase stabilizing eﬀect of the lateral diol

group is largest for the centrally substituted compound 1e and

it decreases on migration of the lateral group to the terminal

end of the rigid core. Thus, a mesophase stabilization in

comparison with the corresponding methyl substituted com-

pounds is observed only for the 2∞-substituted compound,

whereas the clearing temperature of the diol 13 with its polar

group in the 3-position is signiﬁcantly lower than that of the

corresponding 3-methyl derivative 12. Probably two diﬀerent

reasons are responsible for this eﬀect. At ﬁrst the mesophase

destabilizing inﬂuence of lateral substituents depends on their

Fig. 3 Mesomorphic properties of the compounds 1 as a function of

the length of the terminal chains.

J. Mater. Chem., 1998, 8, 2611–2626

2621

Fig. 4 Inﬂuence of the position of the lateral groups on the liquid

crystalline behavior.

position at the rigid core. Those in central positions have a

more pronounced destabilizing inﬂuence than those in more

peripheral positions.1–3,5,18 The reason may be that the lateral

substituents in a central position are forced to be located

between the rigid p-terphenyl cores, whereas those in a peri-

pheral position can be expelled more easily into the region of

the ﬂexible terminal alkyl chains. This would be more favorable

for lipophilic substituents, like the methyl group, than for

polar hydrophilic substituents which are incompatible with the

alkyl groups. This second eﬀect could be responsible for the

destabilization of the smectic layers of the 3-substituted diol

derivative 13 with respect to the methyl substituted

compound 12.

Fig. 5 Properties of 4,4>-didecyloxyterphenyl derivatives with lateral

amide groups.

bonding is larger than the mesophase destabilizing eﬀect due

to unfavorable steric interactions from increasing the size of

the substituents by additional CH OH groups. It is especially

2

remarkable that the acylated aminosugar 2027 exhibits the

most stable smectic phase of all compounds compared in

Fig. 5. This compound represents an entirely new type of

mesogenic carbohydrate derivative, which combines a rigid

rod-like core laterally connected with a polyhydroxy unit. It

seems, however, that this class of compounds is very sensitive

to slight changes of the molecular structure. The N-methyl

amide 21, for example, in which the NH group of 20 is

Remarkably, for all diol substituted compounds, no S

phase was found even on supercooling the samples. It should

C

be mentioned here that this phenomenon is often observed in

systems of calamitic molecules with strong attractive forces

between their rigid cores, especially in donor–acceptor

replaced by a NCH group, is a non-mesogenic solid. It seems

3

systems.30 For example, S phases can be exclusively induced

that the NH group plays an important role as a proton donor

A

in mixed systems of calamitic molecules with donor and

group in the mesophase stabilization of this class of com-

pounds. Likewise, comparison of the ether 1e with the related

amide 19 reveals a mesophase stabilization of 28 K following

acceptor properties30 and in mixed systems consisting of

calamitic mesogens and TNF.31 Steric eﬀects should also

contribute to the loss of S phases. The large lateral substitu-

replacement of the CH O group by a CONH group. However,

C

2

ents disfavor tilting, because this would further enlarge the

the mesophase destabilization on introduction of the N-methyl

lateral cross-section and additionally disturb the packing of

the alkyl chains.

4.3. Variation of the lateral groups

A wide variety of diﬀerent polar groups has been checked. In

Fig. 5 the molecules with lateral amide groups are compared

with the methyl carboxylate 1415,27 which has exclusively a

nematic phase. The amide 15 and the N-ethyl amide 16 are

high melting crystalline solids which rapidly crystallize on

cooling. Therefore no liquid crystalline phases can be observed.

However if one additional proton donating functional group

(OH or NH ) is introduced into the lateral group, then liquid

2

crystalline properties can be found. Both the hydrazide 17 and

the 2-hydroxyethylamide 18 form S phases with signiﬁcantly

A

higher mesophase stability than the ester compound 14.27

Furthermore, with an increasing number of hydroxy groups

in the lateral chain the mesophase stability of the S phase

A

rises (compounds 18, 19 and 20 in Fig. 5). Remarkably, the

mesophase stability increases despite the fact that the lateral

groups are enlarged simultaneously. This means that the

mesophase stabilization provided by the additional hydrogen

Fig. 6 Comparison of the mesomorphic properties of the amides 22,

23 and 24.

2622

J. Mater. Chem., 1998, 8, 2611–2626

Fig. 8 Inﬂuence of the length of the lateral polyether chain on the

mesomorphic properties of 2∞-substituted 4,4>-didecyloxyterphenyl

Fig. 7 Comparison of the phase transition temperatures of the

carboxylic acid 25,27 the corresponding acid chloride 2627 and the

sodium carboxylate 27.

derivatives12 (Col =rectangular columnar mesophase).

r

group is much larger. Therefore, the complete loss of mesogenic

properties for compound 21 could not be explained by the

diminished degree of hydrogen bonding alone. Changes in the

molecular conformation can probably also contribute to this

eﬀect.

Compounds with polar lateral groups without the possibility

of forming hydrogen bonds are in most cases non-meso-

morphic. This is obvious from a comparison of the diol 22

with the morpholide 23, which is the cyclic analogue of the

diol 22 without hydroxy groups (Fig. 6). The azacrown com-

pound 24 is also a crystalline solid.

Intermolecular hydrogen bonding is also important in car-

boxylic acids which are known to form dimers.32 In Fig. 7 the

carboxylic acid 2527 is compared with its acid chloride 26.27

Again the carboxylic acid 25, i.e. the compound which is able

to form hydrogen bonding, displays the higher mesophase

Fig. 9 Optical photomicrograph of the texture of compound 29b

between crossed polarizers at 40 °C. The Col phase (spherulitic

r

texture at the left hand side) is growing out of the homeotropically

aligned domains of the S phase while cooling. Small regions of the

A

homeotropically aligned S phase with some oily streaks can still be

A

seen at the right-hand side.

stability. The ionic amphiphiles, the carboxylate 27 (Fig. 7) as

well as the quaternary ammonium salt 28 are high melting

solids without detectable thermotropic liquid crystalline

properties.

4.4. Polyether amphiphiles

In order to further clarify the relation between molecular

structure and liquid crystalline behavior we have decoupled

the lateral rac-propane-2,3-diol unit from the rigid p-terphenyl

core via hydrophilic polyether chains.12 The phase transition

temperatures of these compounds are collected in Fig. 8. The

clearing temperatures as well as the melting temperatures

decrease signiﬁcantly with increasing length of the oligo-

(oxyethylene) spacer which connects the propane-2,3-diol

group to the rigid core. The clearing temperatures are more

depressed per spacer length increment than the melting tem-

peratures. This results in monotropic mesophases for com-

pounds 29b and 29c with longer oligo(oxyethylene) spacers.

However they can easily be supercooled. The diol 1e and the

ethylene glycol derivative 29a form a smectic A phase as the

only mesophase. On cooling of compound 29b a transition

Fig. 10 Schematic illustration of the S phase and a possible ribbon

A

arrangement for the rectangular columnar phases (Col ) of compounds

r

from the S phase to a columnar mesophase occurs at 40 °C.

29b and 29c.12 The black areas represent the phase separated regions

A

As shown in Fig. 9 the transition to the columnar phase can

of the polar groups. The polar groups of the molecules in the middle

of the ribbons cross over the neighboring calamitic terphenyl units.

be seen in the polarizing microscope by the formation of a

spherulitic texture in the homeotropically aligned S phase.

A

J. Mater. Chem., 1998, 8, 2611–2626

2623

of these layers. The ribbons should consist of parallel rigid p-

terphenyl cores laterally separated by the hydrophilic domains

of the lateral groups. The alkyl chains are molten and ﬁll up

the space between the ribbons in the other dimension. From

the obtained lattice parameter it was calculated that between

four and ﬁve molecules should be arranged in the cross-section

of the ribbons.12 Therefore, the polar lateral groups of the

molecules in the middle of these ribbons must cross over the

neighboring calamitic terphenyl units in order to become

incorporated into the polar regions. In Fig. 11 the CPK models

of four molecules of the tris(oxyethylene) derivative 29c are

placed side by side as they would be arranged in the cross-

section of the ribbons. It shows that indeed the lateral groups

of the molecules in the middle are suﬃciently long to reach

the polar regions. Therefore, we propose that, in addition to

a certain polarity and size, a suﬃcient length of the polar

groups is also an important prerequisite for columnar

mesophase formation in this class of compounds.

Fig. 11 CPK model showing a possible arrangement of the molecules

29c in the cross-section of a ribbon.

The proposed ribbon model seems reasonable, because it

enables the segregation of polar and lipophilic units into

separate regions whereby the parallel organization of the rod-

like molecules is maintained. In respect of the local order

within the ribbons, the columnar phase can be regarded as a

modulated smectic phase, but in comparison to most other

modulated phases the lateral diameter of the ribbons is rather

small. Alternatively, this ribbon structure can be described as

an alternating structure of two types of lamellae. One type

consists of alkyl chains and the second type is composed of

ribbons of rigid p-terphenyl units laterally separated by cylin-

ders containing the hydrophilic groups [see Fig. 12(a)]. This

model is related to that suggested for supermolecular structures

which have recently been found in triblock copolymers con-

sisting of three linearly combined ﬂexible blocks [see

Fig. 12(b)].33 Here, beside other superstructures, lamellae with

cylinders at the lamella interfaces have been found.34 Indeed,

the molecules described here can be regarded as low molecular

weight three-block compounds composed of three diﬀerent

and incompatible blocks: the rigid cores, the ﬂexible and

lipophilic alkyl chains and the ﬂexible but polar polyether

chains. In contrast to linear triblock copolymers, the Y-shaped

block molecules described here have the cylinders located

within one of the distinct layers instead of being located at

their interface. There are at least two reasons for their position

within the layer of the rigid cores. At ﬁrst, this organization

is provided by the ﬁxation of the polar groups in a central

lateral position. Additionally, the rigidity of central rod-like

block reduces the number of possible conformations and thus

Fig. 12 Schematic representation of the lamellae-cylinder structures

of (a) the Col phases of compounds 29b and 29c and (b) of a

r

microphase segregated linear ABC triblock copolymers.33,34

From the X-ray diﬀraction pattern and taking into account

the molecular dimensions a rectangular columnar structure

was suggested for this mesophase.12 Compound 29c with a

longer polyether chain exhibits exclusively the (monotropic)

rectangular columnar mesophase (Col ). For these columnar

r

phases a ribbon structure as shown in Fig. 10 was proposed.12

According to this model, the ﬂexible and polar polyether

chains should segregate from the rigid cores into separate

domains and thus give rise to a collapse of the smectic layers

into ribbons which can be regarded as small band like segments

Fig. 13 Inﬂuence of the structure of the lateral group on the mesomorphic properties of the 2∞-substituted p-terphenyl derivatives (M=unknown

mesophase with schlieren texture).

2624

J. Mater. Chem., 1998, 8, 2611–2626

the rigid cores, and also a certain polarity of the lateral

substituents (polyether chains instead of alkyl chains), are

both necessary for the occurrence of columnar mesophases.

4.5. Crown ether derivatives

The crown compounds 33a–c36 (Fig. 14) represent closed

analogues of compounds 29 and 30. Because of the absence

of proton donor groups they lack the possibility of hydrogen

bonding. As mentioned in the introduction, such large lateral

groups usually suppress smectic phases and give rise to nematic

phases. Also the laterally alkyl-substituted terphenyl deriva-

tives 2 (see Fig. 2) and 32 (Fig. 13) have exclusively nematic

phases. No smectic phase can be observed on cooling com-

pound 32 until crystallization sets in at 15 °C. The crown

compounds 33, however, have an S –N dimorphism in contrast

A

to the alkyl substituted compounds 2 and 32. This means that

layer structures are preferred by these polyethers. Probably

the polar crown ether groups can force micro-segregation

between the central regions consisting of the rigid cores and

the crown ether units from the terminal lipophilic alkyl chains.

Thus, in the crown compounds the steric disturbance of the

lateral groups is in competition with the layer stabilizing eﬀect

provided by micro-segregation.37

Fig. 14 Inﬂuence of the size of laterally attached crown units on the

mesomorphic properties of the facial amphiphiles.

inhibits the organization of the molecules in a conventional

inverted hexagonal columnar mesophase as known for ﬂexible

double chain amphiphiles and taper shaped molecules.35

In order to further evaluate the structural requirements

which are responsible for the occurrence of columnar meso-

phases, compound 32 with a lateral alkyl chain, compound 31

with a 1,2-diol unit coupled via a hydrophobic alkyl spacer,

and two oligo(oxyethylene) ethers without diol units (com-

pounds 30) were investigated. As shown in Fig. 13 the colum-

nar phase is replaced by a smectic A phase if one of the

hydroxy groups in the polar group is removed (compounds

30). A nematic phase is found if the polyether chain is replaced

by a lipophilic alkyl chain (compound 32). If a diol group is

attached to the end of the lateral alkyl group (compound 31)

a monotropic mesophase with a schlieren texture is observed.

Because compound 31 rapidly crystallizes we were not able to

4.6. Inﬂuence of the position of the polyether chain

As mentioned above the 3-substituted diol 13 has a signiﬁcantly

higher smectic mesophase stability than the corresponding 2∞-

substituted molecule 1e (see Fig. 4). Also the 3-substituted

polyether compounds 34 (Fig. 15) have enhanced clearing

temperatures in comparison to the 2∞-substituted analogues 29

(Fig. 8). Remarkably however, only S phases and no colum-

A

nar mesophases could be detected for the diols 34b and 34c

with long polyether chains in the peripheral 3-position at the

rigid core. It seems that the formation of columnar mesophases

is bound to a very special molecular structure and it is favored

by a central attachment of the polar group.

Also in the series of 3-substituted compounds the polyether

chains were replaced by alkyl chains (see Fig. 15). Compound

35a in which one ether oxygen in the lateral chain of 34a is

diﬀerentiate between an S phase and a nematic phase.

C

Nevertheless, these structural variations show that a suﬃcient

replaced by a CH group has a slightly decreased mesophase

2

number of hydrogen bonding sites (diols vs. simple alcohols)

stability. No mesomorphic properties can be found for com-

providing suﬃciently strong attractive interactions between

pound 35b in which the diol group is decoupled by a long

Fig. 15 Inﬂuence of the structure of the lateral group on the mesomorphic properties of 3-substituted 2,2>-didecyloxyterphenyl derivatives.

J. Mater. Chem., 1998, 8, 2611–2626 2625

14 (a) N. Miyaura, K. Yamada and A. Suzuki, Tetrahedron Lett.,

1979, 3437; (b) M. Hird, G. W. Gray and K. J. Toyne, Mol. Cryst.

Liq. Cryst. Lett., 1991, 206, 187; (c) M. Hird, G. W. Gray and

K. J. Toyne, Liq. Cryst., 1994, 16, 625.

alkyl spacer. This could be due to the poor supercoolability

of this compound (85 °C).

15 J. Andersch and C. Tschierske, Liq. Cryst., 1996, 31, 51.

16 C. D. Hurd and M. A. Pollack, J. Am. Chem. Soc., 1938, 60, 1908.

17 V. van Rheenen, R. C. Kelley and D. F. Cha, Tetrahedron Lett.,

1976, 1973.

18 J. Andersch, C. Tschierske, S. Diele and D. Lose, J. Mater. Chem.,

1996, 6, 1297.

19 Obtained by NBS bromination of 5-decyloxy-2-(4-decyloxy-

phenyl)toluene, which was prepared by Suzuki coupling of 2-

bromo-5-decyloxytoluene with 1 equiv. of 4-decyloxyphenyl-

boronic acid analogous to the synthesis of 39 (Scheme 4) (ref. 18).

20 Obtained by NBS bromination of 3,5-bis(4-decyloxyphenyl)tolu-

ene, which was prepared by Suzuki coupling of 3,5-dibromotolu-

ene with 2 equiv. of 4-decyloxyphenylboronic acid, analogous to

the synthesis of 2,5-bis(4-decyloxyphenyl)benzyl bromide

(ref. 15).

5. Conclusions

The investigations have shown that—depending on the

molecular structure—facial amphiphiles can form monolayer

S

phases and columnar mesophases. Micro-segregation and

A

cohesive forces provided by hydrogen bonding stabilize a

parallel layer-like arrangement of the calamitic molecules. If

the polar groups are hydrogen bonding functional groups,

their mesophase stability can be higher than that of related

compounds with smaller lateral substituents. However, the

stabilization of layered mesophases is in competition with the

disturbance provided by the space ﬁlling of these substituents.

Furthermore, in many cases (e.g. ionic amphiphiles) the high

melting temperatures and the poor supercoolability of the

materials prevents potential (monotropic) mesophases from

being observed.

21 R. Adams and L. H. Ulich, J. Am. Chem. Soc., 1920, 42, 599.

22 R. Plehnert, J. A. Schroter and C. Tschierske, Langmuir, 1998,

¨

14, 5245.

23 J. Goerdeler, Houben-Weyl, Methoden der Organischen Chemie,

Georg Thieme Verlag, Stuttgart, 1958, vol. 11/2, p. 591.

24 M. Hird, A. J. Seed, K. J. Toyne, J. W. Goodby, G. W. Gray and

D. G. McDonnell, J. Mater. Chem., 1993, 3, 851.

25 F. Hentrich, C. Tschierske, S. Diele and C. Sauer, J. Mater.

Chem., 1994, 4, 1547.

In cases of compounds with rather large, ﬂexible and polar

lateral substituents ﬁxed to the center of the rigid terphenyl

unit (compounds 29b and 29c, see Fig. 8) columnar mesophases

can be found. These columnar phases should represent ribbon

phases resulting from the collapse of the smectic layers. The

lateral polyether chains are incompatible with the rigid and

lipophilic p-terphenyl units and segregate from them into

separate cylindrical domains which interrupt the smectic layers.

These molecules can be regarded as block molecules composed

of three diﬀerent and incompatible molecular parts. It could

be expected that the design of novel types of low molecular

weight block compounds consisting of three or even more

diﬀerent and incompatible molecular parts connected via

diﬀerent topologies might provide interesting new liquid

crystalline materials.37,38

26 D. Landini, F. Montanari and F. Rolla, Synthesis, 1979, 134.

27 F. Hildebrandt, J. A. Schroter, C. Tschierske, R. Festag,

¨

R. Kleppinger and J. H. Wendorﬀ, Angew. Chem., 1995, 107, 1780;

Angew. Chem., Int. Ed. Engl., 1995, 34, 1631.

28 Although the mesophase stabilization by hydrogen bonding is well

documented for calamitic molecules with terminal hydrogen bond-

ing (ref. 10, 32) and for taper-shaped polyhydroxy compounds

[ref. 35(c),(d)], the mesophase stabilization by a laterally attached

diol group is rather surprising. The formation of an S phase for a

A

compound with laterally attached hydroxy groups was only

reported for some inositol ethers (K. Praefcke and D. Blunk, Liq.

Cryst., 1993, 14, 1181; K. Praefcke, D. Blunk and J. Hempel, Mol.

Cryst. Liq. Cryst., 1994, 243, 323.)

Finally, it should be mentioned that all compounds with

hydrophilic lateral groups can form lyotropic mesophase, as

will be reported in a separate paper.13

29 C. Tschierske, J. Mater. Chem., 1998, 8, 1485.

30 (a) K. Praefcke and D. Singer, in Handbook of Liquid Crystals, ed.

D. Demus, J. Goodby, G. W. Gray, H.-W. Spiess and V. Vill,

Wiley-VCH, Weinheim, 1998, vol. 2b, p. 945; (b) R. Dabrowski

and K. Czuprynski, in Modern Topics in Liquid Crystals, ed.

A. Buka, World Scientiﬁc, 1993, p. 124.

Acknowledgments

This

work

was

supported

by

the

Deutsche

31 (a) B. Neumann, D. Joachimi and C. Tschierske, Liq. Cryst., 1997,

22, 509; (b) R. Lunkwitz, B. Neumann and C. Tschierske, Liq.

Cryst., 1998, 25, 403.

Forschungsgemeinschaft and the Fonds der Chemischen

Industrie.

32 C. M. Paleos and D. Tsiourvas, Angew. Chem., 1995, 107, 1839.

33 W. Zheng and Z.-G. Wang, Macromolecules, 1995, 28, 7215.

34 C. Auschra and R. Stadler, Macromolecules, 1993, 26, 2171.

35 (a) A. Eckert, B. Kohne and K. Praefcke, Z. Naturforsch., 1988,

43b, 878; (b) K. Praefcke, B. Kohne, A. Eckert and J. Hempel,

Z. Naturforsch., 1990, 45b, 1084; (c) K. Praefcke, P. Marquardt,

B. Kohne and W. Stephan, J. Carbohydr. Chem., 1991, 10, 539;

(d) G. Lattermann and G. Staufer, Liq. Cryst., 1989, 4, 347;

6. References

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37 C. Tschierske, J. Mater. Chem., 1998, 8, 1485.

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J. Am. Chem. Soc., in the press.

Paper 8/03043J

2626

J. Mater. Chem., 1998, 8, 2611–2626

Article Doi

Synthesis and thermotropic liquid crystalline properties of calamitic molecules with laterally attached hydrophilic groups: Y-shaped three-block molecules which can form smectic and columnar mesophases

DOI: 10.1039/a803043j

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Article abstract of DOI:10.1039/a803043j

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