~~~~~~ ~ ~ ~ ~ ~ Molecular design of amphotropic materials: influence of oligooxyethylene groups on the mesogenic properties of calamitic liquid crystals Bernhard Neumann,‘ Christiane Sauer,b Siegmar Dieleb and Carsten Tschierske* aMart in -Luther-Universi ty Ha 11e-Wit te n berg, Depart men t of Chemistry, Institute of 0rga n ic Chemistry, We inb ergw eg 16, 0-06120 Halle, Germany bMartin-Luther-UniversityHalle- Wittenberg, Department of Chemistry, Institute of Physical Chemistry, Muhlpforte 1, 0-06099 Halle, Germany The syntheses and liquid-crystalline properties of novel oligoethylene glycol derivatives are described These are amphiphiles and podand-like trimesogens The hydrophobic sections of the amphiphiles consist of calamitic 4-( 5-pentadecyl- 1,3,4-thiadiazol-2-y1)- phenyl, 4’-dodecyloxybipheny1-4-y1or 4-decylphenyl units, which are connected by a hydrophilic 12,13-dihydroxy- 1,4,7,10- tetraoxatridecyloxy, 9,lO-dihydroxy- 1,4,7-trioxadecyloxy, 6,7-dihydroxy-1,4-dioxaheptyloxyor 2,3-dihydroxypropoxy groups All these amphiphiles contain a 1,2-diol unit In addition the 12-hydroxy-1,4,7,10-tetraoxadodecyl-,9-hydroxy-1,4,7-trioxanonyl, 6-hydroxy- 1,4-dioxahexyl and 2-hydroxyethoxy derivatives of 4’-dodecyloxybiphenyl are described These compounds have only a single hydroxy group at their hydrophilic termini The podand-like trimers consist of three 4’-dodecyloxybiphenyl units which are connected via oligooxyethylene chains with an a, a’,a”-mesitylenetriyl unit The thermotropic liquid-crystalline properties of these compounds were investigated by polarising microscopy, differential scanning calorimetry and, in some cases by X-ray scattering Most diol derivatives exhibited an SA-S, dimorphism However, one of the biphenyl derivatives [4-dodecyloxy-4’-( 6,7-dihydroxy- 1,4-dioxaheptyl)biphenyl] displays another phase instead of the S, phase, probably a phase with a ribbon structure The liquid- crystalline phases of these diol derivatives were influenced by the addition of protic solvents Only lamellar phases were found for the biphenyl derivatives Some thiadiazole derivatives additionally formed lyomesophases consisting of curved aggregates No thermotropic liquid crystalline properties could be detected for the oligoethylene glycol monoethers without the 1,2-diol group However, lyotropic liquid-crystalline phases could be induced by the addition of ethylene glycol or formamide Only those podands with a medium spacer length were thermotropic liquid crystals and no lyotropic mesophases were detected for the podands Some organic compounds can form fluid phases exhibiting anisotropic physical properties, resulting from the orientational order of the anisometric (calarnztzc=lath-like or discotic=disc-like) individual molecules These thermotropic liquid crystals play an important role in materials science and may be used for optoelectronics, information storage and self-reinforcing plastics Amphiphilic molecules consist of a polar head group which is connected to one or more flexible hydrophobic chains They form a wide variety of self-organising systems, such as micelles, monomolecular layers at interfaces and also liquid crystalline phases, which consist of anisometric polymolecular aggregates Many efforts have been made to combine these two types of mesomorphic materials to produce amphotropic liquid crystals In this context, tetraethoxycholesteryl semisuccinate has been reported, which combines the hydrophilic oligoethyl- ene glycol group with the hydrophobic rigid cholesteryl moiety However, several previous attempts were made to introduce rod-like molecular units into the hydrophobic part of oligoethylene glycol amphiphiles, and with one exception5 all the compounds described previously exhibited only lyotropic properties after the addition of water The amphotropic behaviour of simple alkane- 1,2-diols has recently been reported Their combination with rigid cores gives rise to extended thermotropic and lyotropic meso-morphic ranges In order to clarify further the relation between molecular structure and amphotropic behaviour, we herein report on new amphiphilic oligoethylene glycol derivatives incorporating ethers lo Furthermore, the terminal hydroxy groups were replaced by diol head groups or central linking units Results and Discussion Synthesis The synthesis of the diols is displayed in Scheme 1 Compounds 5, which possesses a podand-like structure with a central benzene ring coupling the mesogenic biphenyl units via oligooxy-ethylene spacers, were obtained in a multistep synthesis as outlined in Scheme 2 for the synthesis of the triethylene glycol derivative 5c Thereby 4’-dodecyloxy-4-hydroxybiphenylwas etherified by the Mitsunobu method using 10-phenyl-3,6,9-trioxadecano112 followed by hydrogenolytic debenzylation Alternatively 4 -dodecyloxy-4-hydroxybiphenyl could be etherified directly by reaction with 8-chloro-3,6-dioxaoctanolin the presence of potassium carbonate13 and tetrabutylammonium iodide l4 Both methods gave comparable yields of the oligoethylene glycol monoether 4c.After alkylation with 1,3,5-tris( bromome- thyl)benzene15 in the presence of potassium hydride in THF16 the podand 5c was obtained In order to evaluate the influence of the oligooxyethylene spacer on the mesomorphic properties of these compounds, the trimesogens 7, in which the oligooxyethylene chains are replaced by alkyl chains, were synthesised according to Scheme3 Owing to the readily occurring cyclisation of 4- bromobutanol under basic conditions, 4-tetrahydropyranyl- oxybutanol was used for the synthesis of compound 7b (n=4) different rigid cores and oligooxyethylene chains of different lengths Therefore, single phenyl rings, biphenyl ring systems Thermotropic behaviour or 2-phenyl-1,3,4-thiadiazoleunits were introduced into the The mesomorphic behaviour of the compounds synthesised hydrophobic sections of oligoethylene glycol monoalkyl- was investigated by polarised light micro~copy,~’ differential J Muter Chem, 1996, 6(7), 1087-1098 1087 L I L J" 8 9 MeOH, HlO 1cat.Py TosOH n =0,2,3 Scheme 1 Synthesis of the amphiphilic diols 1-3 1oc nnn0 0 OH HO 0 KZCOS, Bu~N'I' EtOOC-N=N-COOEt, PPh, AAA H2, Pd/C nnon C12H250w0 OH 4cIlc KH, cat Bu4N'I' THF Br Cl~H250-~OnOnOA0 5c C12H250-0 \ / \/ w0uw0 Scheme 2 Synthesis of the podand-like trimesogen 5c 1088 J. Muter. Chem., 1996, 6(7), 1087-1098 Table 1 Transition temperatures/"C and associated enthalpy values/kJ mol- (lower lines in brackets) of the pure and ethylene glycol-saturated samples of the biphenyl derivatives la-d" pure compound ethylene glycol-saturated sample comp n K, K2 SC I K SA I ~~ ~ ~ la 0 0 142 0 176 - (6 2) (273) lb 1 0 124 0 140 X (20.7) (172) lc 2 0 117 0 122 0 (15.5) (163) Id 3 0 - 0 112 0 (34.8) "K, crystalline solid, SA, smectic A phase; S,, smectic C phase, X, unknown mesophase; I, isotropic liquid.KH, cat. Bu,N'I' TH F Br 7a: n = 3 7b:n=8 7c: n= 11 Scheme 3 Synthesis of 1,3,5-tris[o-(4'-dodecyloxybipheny1-4-yloxy)-2-oxaalkyl] benzenes 7a, c and d scanning calorimetry and, in some cases, also by X-ray diffrac- tion measurements. For this purpose the samples were dried simply by heating on a cover glass for 1 min to a temperature ca. 60 "C above the clearing temperature.? Afterwards the samples were immediately sealed. The phase-transition tem-peratures and associated enthalpies are collected in Tables 1-7.Biphenyl derivatives incorporating an 1,2-diol structure. The biphenyl-derived diols 1 exhibit a smectic A (S,) phase as the high-temperature mesophase. The clearing temperatures and the melting temperatures decrease significantly with increasing length of the oligooxyethylene chain (Table 1). The biphenyl derivatives incorporating at least one oxyethyl- ene unit (lb-ld) display an additional phase transition within t The dependence of water desorption on the temperature was investigated by means of a special apparatus. Dry air was passed over a thermostatted sample of the diol The amount of desorbed water was determined by passing the gas through a Karl-Fischer apparatus l8 This method will be described in detail in a separate paper l9 Plate 1 Optical photomicrograph of the texture of the thermotropic S, phase of compound lc at 125°C as obtained by cooling the homeotropically aligned S, phase (crossed polarisers) the liquid crystalline state. Using polarising optical microscopy, in the cases of compounds lc and Id a schlieren texture was observed (Plate l), which is typical for the tilted smectic C (S,) phase.The X-ray patterns of the Sc and SA phases exhibited the characteristic features of these smectic phases with no order in the layers. Using CPK models and assuming an all-trans conformation for the alkyl chains and mainly gauche confor- mations for the oligooxyethylene chains, the molecular length of lc was estimated to be ca. 3.7 nm. Thus the thickness (d) of the smectic layers (d= 5.92 nm at 140"C) is significantly larger than the length of the individual molecules.This means that the molecules should be arranged in bilayersx with the diol groups placed between the layers.20 The dependence of the layer thickness on the temperature was investigated for com- pound lc (Fig. 1). In the Sc phase a typical temperature dependence was established: d decreases with decreasing temperature, which is due to the increasing tilt of the molecules. From this tempera- ture dependence a variation of the tilt angle from 0' (at the transition to the SA phase) to 11.3" (at 130°C) was estimated. In the SA phase, d is also clearly a function of temperature; however, d decreases with increasing temperature.This effect can be interpreted by a growing number of gauche confor- mations of the alkyl chains at higher temperatures. $ The layer thickness amounts less than twice the molecular length, because the alkyl chains are in a molten, liquid-like state and probably also because of the partial intercalation of the terminal groups J. Muter. Chew., 1996, 6(7), 1087-1098 1089 -62 -60 50 -?. 7J -56 0 52 110 120 130 140 150 160 170 Tl"C Fig. 1 Temperature dependence of the layer thickness of compounds lb and lc as determined by X-ray scattering In contrast to lc and Id, the low-temperature phase of compound lb displays a different texture (Plate 2) which is similar to the textures of lyotropic hexagonal and some thermo- tropic columnar phases.In the X-ray pattern of the S, phase of this compound (Fig. 2) the layer reflection and its second order, and an outer diffuse scattering (not displayed) were found. By cooling the sample to the X phase the outer amorphous halo was main- tained but an additional scattering of low intensity was detected in the small-angle region. The position of this reflection relative to the first one does not correspond to the ratio 1:,/3; Therefore a hexagonal columnar arrangement can be excluded. Plate 2 Optical photomicrograph of the texture of the thermotropic X phase (at 144 "C) obtained by cooling the homeotropically aligned SA phase of compound lb (crossed polarisers) 6000 I 1 a 130 OC I 0.8 1.o 1.2 1.4 1.6 I .8 eldegrees Fig. 2 X-Ray scattering (small-angle region of the Guinier-goniometer traces) of compound lb at different temperatures: (150 "C=S, phase; 140 "C=X phase; 130 "C=crystalline state) 1090 J.Muter. Clzem., 1996, 6(7), 1087-1098 SA X phase? Fig. 3 Schematic representations of the SA phase and two possible ribbon-like phases of compound lb This additional reflection disappears in the crystalline state. For the X phase, d is nearly independent of temperature (Fig. 1). Attemps to obtain oriented samples by applying a magnetic field were unsuccessful. The diffuse scattering in the wide-angle region suggests that the X phase is a phase with liquid-like behaviour concerning the lateral molecular distances. If it were smectic, it could be either an SA or an S, phase.The texture, however, is not characteristic of either of these phases. Taking into account all these observations, it seems possible that in the X phase the molecules are arranged in ribbons. Ribbon structures have been described for thermotropic phases of soaps2' and also for the low-temperature phase of a highly polar calamitic nitroben- zoate.22 These ribbons may result from the break up of the smectic layers due to the different space filling of the hydro- philic and the hydrophobic regions (Fig. 3). In order to evaluate this hypothesis, further experiments have been carried out. Protic solvents should increase the size of hydrophilic units and thus influence the mesophases.§ It was found that upon the addition of formamide the thermo- tropic X phase of compound lb was replaced by an Sc phase which changes by larger amounts of solvent to an SA phase.Also, in the contact zone of compound lb with the diethylene glycol derivative lc the X phase of lb was destabilised, whereas the S, phase of compound lc is slightly stabilised. Therefore it may be assumed, that the 6,7-dihydroxy-1,4-dioxaheptyl group of compound lb is a hydrophilic group which allows particularly efficient packing. Accordingly, the area of the hydrophobic sections should be greater than that of the hydrophilic regions, thus giving rise to the frustration of the layered arrangement. Interestingly, compound le, in which one ether oxygen of compound lb is replaced by a methylene group, does not display the X phase, but an Sc phase.\-I lb (X=O) K 140 X 146 SA 169 I le (X=CH2) K 134 S, 157 SA 169 I In order to further verify this hypothesis, further synthetic activities as well as physical measurements to characterise these phases are in progress. The thiadiazoles 2 (Table 2) exhibit exclusively an Sc-SA dimorphism and their transition temperatures decrease with increasing length of the oligooxyethylene spacer. The decrease of the Sc-SA transition with growing spacer 9 A more detailed discussion of the lyotropic behaviour is given later. Table 2 Transition temperaturesrc and associated enthalpy values/kJ mol (lower lines in brackets) of the water-free samples of the thiadiazole derivatives 2a9"and 2b-d phase transitions comp n K, SC I 2a 0 0 105 112 0 114 (52 O)b 2b 1 0 88 97 0 109 (21 3) (11 2) (1 9) 2c 2 72 0 91 101 (20 1) (12 4) (2 4) 2d 3 0 67 84 90 (13 7) (16 7) (4 2) "Abbreviations as in Table 1 bPhase transitions K, -+K,-+Sc-+SA are not resolved transition enthalpies refer to the total amount of these transitions length is less pronounced than for the other phase transitions This gives rise to an increase of the Sc range with increasing number of oxyethylene units The diols 3, incorporating only a single phenyl ring (Table 3) are also liquid crystals, but they form the SAphase exclusively Even diols without any anisometric unit, such as the hexade- cylether 9,23 exhibit thermo tropic liquid-crys talline phases 9 K <20 Lo 37 I This indicates that hydrogen bonding is a main driving force for the self-organisation of these amphiphilic compounds Hydrogen bonds between the diol groups and also between the hydroxy groups and the ether oxygens give rise to the formation of large hydrogen-bonding networks, which force the individual molecules to organise as mesophases 24 In these hydrogen bonds the two hydroxy groups of the diol units act Table3 Transition temperatures/"C and associated enthalpy values/kJ mol (lower lines in brackets) of the water-free samples of the phenyl derivatives 3a9eand 3b-d" r i/-OH phase transitions comp n K SA I 3a 0 0 68 0 91 0 3b 1 0 46 0 69 0 (38 3) (1 2) 3c 2 0 7 0 60 0 (25 0) (12) 3d 3 0 9 0 49 0 (43 6) (1 5) "Abbreviations as in Table 1 as proton donors as well as proton acceptors, whereas the ether oxygens act exclusively as acceptors Oligoethylene glycol monoethers.No thermotropic liquid- crystalline properties could be detected for the biphenyl deriva- tives 4 in which the terminal diol groups are replaced by a single hydroxy group (Table 4) Obviously a single proton- donating hydroxy group is not sufficient to produce stable aggregates which enable the formation of thermotropic liquid- crystalline phases Thermomesomorphic properties of podands and trimesogens. It seems that sufficiently strong terminal fixation of the individ- ual molecules via hydrogen bonding stabilises liquid-crystalline phases But can the covalent fixation of the individual calamitic mesogens via the termini of their oligooxyethylene chains replace the hydrogen bonding, and thus also give mesomorphic materials? This concept was realised by the podand-like trimesogens 5, in which the individual molecules are connected by a central mesitylene unit The transition temperatures of these podands are summarised in Table 5 Only compound 5b exhibits an S, phase over a small temperature range In order to evaluate the influence of the oligooxyethylene spacer on the mesomorphic properties of these trimesogens, compounds 7, in which the oligooxyethylene chains are replaced by alkyl chains, were also investigated (Table 6) Again, only the trimesogens 7a and 7b with medium spacer lengths display liquid-crystalline behaviour These com- pounds may be regarded as oligomeric liquid crystals In accordance with our recent results,25 only those oligomeric liquid crystals in which the calamitic units are decoupled by a spacer of medium length from the central linking unit display liquid-crystalline properties Mesomorphic properties in the presence of solvents Nonionic amphiphilic oligoethylene glycol alkyl ethers are known to exhibit lyotropic liquid crystalline phases in aqueous solution in defined concentration and temperature regimes lo 26 Thereby the mesophases are determined by the concentration, the temperature and the relation between the hydrophobic tails and hydrophilic head groups of the amphiphiles Owing to their amphiphilic structures the diols 1-3, the oligoethylene glycol monoethers 4 and the trimers 5 are assumed to self-organise in water or other protic solvents to give lyotropic mesophases We have studied the behaviour of compounds 1-5 in the presence of protic solvents using the solvent-penetration technique The pure amphiphiles were surrounded by the solvent between two cover slips These samples were then placed on a heating stage and the contact region was observed by means of optical microscopy between crossed polarisers The penetration of the solvent into the sample gives rise to a concentration gradient at the amphiphile/ solvent boundary, and the lyomesophases formed develop as bands and can be monitored as a function of the temperature Mesophases of diols in the presence of water.It was found that in the presence of water all the diol derivatives 1-3 form mesophases with clearing temperatures significantly above 100°C In the case of the biphenyl derived diols 1 the S,-S, transition temperature decreases significantly with increasing water concentration and the water-saturated samples exhibit exlusively the lamellar SAphase between the melting point and 100°C (Plate 3) Obviously the long alkyl chains, the limited length of the oligooxyethylene groups and the rigid biphenyl cores inhibit the formation of curved aggregates The thiadiazole derivatives 2, however, exhibit a more complicated phase behaviour Owing to the ability of the thiadiazole unit to participate in hydrogen bonds, the water J Muter Chern, 1996, 6(7),1087-1098 1091 Table 4 Transition temperatures/"C of the pure, ethylene glycol-saturated and formamide-saturated samples of the oligoethylene glycol monoethers 4a-d" ri comp n pure compound mP 4a 0 138 4b 1 128 4c 2 115 4d 3 104 "Abbreviations as in Table 1 ethylene glycol-saturated sample formamide-saturated sample K SA I K s'4 I a a110 124 a a a105 142 a a a98 133 a a a111 149 a a 098 124 a a 097 144 a a a93 122 a a a92 141 a Table 5 Transition temperatures/"C of the podand-like trimesogens 5a-d" (O \p / O \ /m 0c12H25 phase transitions comp n K SA I 5a 1 a 180 --a 5b 2 a 130 a 131 a 5c 3 a 120 --a -5d 4 a 106 -a "Abbreviations as in Table 1 Table 6 Transition temperaturesrc of the trimesogens 7a-d phase transitions comp n K sx SA I 7a 3 a 7 a 115 a 133 a 7b 4 a 7 a 131 a 141 a ----a7c 8 a 109 7d 11 a 119 --a "Sx,smectic low-temperature phase of unknown structure Other abbreviations as in Table 1 uptake is increased, and mesophases consisting of curved aggregates could also be obtained Compound 2d was used for preliminary phase-behaviour investigations With increasing water content the Sc-SA trans-ition temperature decreases rapidly and finally the Sc phase disappears Further increasing the water content gives rise to the formation of a hexagonal columnar (H,) phase at tempera- tures below the SA phase with a maximum of the H,-SA transition at 70 "C Increasing the water concentration still further slightly decreases the stability of the H, phase In the water-saturated state the SA-H, transition appears at 68 "C A section of the contact region between compound 2d and water at 69 "C is shown in Plate 4 On cooling the H, phase of the water-saturated sample, the transition to an isotropic (probably cubic) phase was observed 1092 J Muter Chem, 1996, 6(7), 1087-1098 at 64 "C Crystallisation occurs at 55 "C and reheating gives a melting point of approximately 67 'C Mesophases of diols in the presence of protic solvents.With the use of other protic solvents, such as ethylene glycol or formamide, broad mesomorphic ranges could also be observed These solvents can form hydrogen bonds with the polyether chains and thus allow the formation of lyotropic mesophases With increasing ethylene glycol concentration the clearing temperatures and the other phase transitions are depres-sed Obviously the incorporation of ethylene glycol into the hydrogen-bonding networks of the diol groups disturbs the mesophase formation In particular, the Sc-SA transition tem- perature decreases with increasing solvent concentration and therefore the S, phase was the only mesophase which was Plate 3 Optical photomicrograph of the oily streaks texture of the lyotropic s* phase Of the water-saturated compound Id at 96 "c (crossed polarisers) Plate 4 (u) Section of the contact zone of compound 2d with water at 69°C as seen between crossed polarisers (pure 2d on the left).(b)Texture of the H, phase appearing in the contact zone of compound 2d and water at 70 "C (crossed polarisers). observed for the solvent-saturated samples. The transition temperatures of the ethylene glycol-saturated samples of the compounds 1 are included in Table 1. Upon the addition of formamide, however, the stability of the SA phase is increased dramatically. The clearing temperatures are very high, and before they are reached extensive decomposition occurs (at 170-190 "C). The thiadiazole derivatives 2 are fairly soluble in formamide, especially at higher temperatures. The greatly increased solu- bility in polar must be caused by the This gives rise to the more COmPlicated Phase behaviour of the thiadiazole derivatives 2c and 2d in the presence of solvents.For example, a lyotropic nematic (N) phase appears in the mixture of compound 2c with ethylene glycol (Plate 5). Mesophases of the oligoethylene glycol monoethers in the presence of water and other protic solvents. In the case of the oligoethylene glycol monoethers 4 the rather high melting point obviously inhibits the formation of lyotropic phases with water below 100"C. However, by using other protic solvents with elevated boiling points, such as ethylene glycol or formam- ide, broad mesomorphic ranges could be induced (Table 4). In this way these oligoethylene glycol monoethers 4 are not amphotropic, but are lyotropic liquid-crystalline materials.The high-temperature mesophase is the SAphase. Only in two cases are additional mesophases found to occur: the induction of an Sc phase was observed at the phase boundary of the triethylene glycol derivative 4c and formamide in the temperature range 97-1 13 "c, and in the formamide-rich region of the &ethylene glycol derivative 4b, a H, phase, was observed within a limited concentration and temperature range below the S, phase (transition to S, occurs at 122°C. Neither the Sc phase nor the columnar phase could be observed for any of the other 4-solvent systems. Behaviour of the podands in the presence of water and other protic solvents. In the case of the podand-like trimers 5 no mesophases could be induced by water, ethylene glycol or formamide.It seems that the central hydrophobic connecting unit inhibits the uptake of solvent molecules. Conclusions Amphotropic materials can be generated by combination of amphiphilic oligoethylene glycol monoalkyl ethers" with appropriate hydrophilic terminal groups such as the diol group (Table 7). The formation of liquid-crystalline phases in these compounds is caused mainly by the hydrogen bonding net- works between their diol groups. The mesophases could be additionally stabilised or modified by the incorporation of rigid units (e.g. phenyl, biphenyl, 2-phenylthiadiazole), which arrange favourably parallel to each other. Alternatively, mesophase stabilisation could be achieved by the addition of solvents such as water and formamide, which reinforce the hydrogen-bonding networks between the hydrophilic units.In the absence of the diol unit no thermo- tropic properties were found, but lyotropic mesophases could still be induced by protic solvents. No mesophase induction by protic solvents was possible, however, if the termini of the oligooxyethylene chains were connected with hydrophobic substituents as in the case of the podand-like trimers 5. Plate 5 Optical photomicrograph of the lyotroplc nematic phase in the contact zone of compound 2c with ethylene glycol at 71 "C (crossed polarisers) J. Mater. Chem., 1996, 6(7), 1087-1098 1093 Table 7 Comparison of the clearing temperatures of the thermotropic and lyotropic mesophases" of the tetraethylene glycol hexadecyl ether 8" and the 1,2-diols9,23Id and 3d TImax/"C compound thermotropic 1yotropic 8 not liquid-crystalline 78 9 37 >100 c1 6H330 3d 49 >100 Id 135 >100 ~ ~~ "TImax =maximal values of the clearing temperature, observed in mixtures with water, determined by the solvent penetration method Experimental Section General Remarks 4'-Dodecyloxybipheny1-4-01,~~4-decylphenol, 4-( 5-pentadecyl- 1,3,4-thiadiaz01-2-yl)phenol,~~4-allyloxyethan01,~~ 1,3,5- tris( bromomethyl) benzene15 and the 1,2-O-isopropylidene-functionalised alcoholsgd were synthesised according to litera- ture procedures co-Bromoalkanols, co-chlorooligooxyethylene ethanols and diethyl azodicarboxylate (Aldrich) were used as received Confirmation of the structures of intermediates and products was obtained by 'H NMR spectroscopy (Varian Unity 500 or Bruker WP200 spectrometers), IR spectroscopy (Specord 71 IR) and mass spectrometry (AMD 402, electron impact, 70eV) The purity of all compounds was checked by thin layer chromatography (Merck, silica gel 60 F254) Light petroleum-ethyl acetate mixtures and chloroform-methanol mixtures (10 0 5) were used as eluents and the spots were detected by UV irradiation and/or by means of bromothymol blue solution Microanalyses were performed using a Leco CHNS-932 elemental analyser Most compounds incorporating at least one oxyethylene unit rapidly take up moisture from the air As determined by the Karl-Fischer method,I8 the water uptake is cu 0 5 mol,l9 while the phenyl derivatives 3 take up even larger amounts Therefore, the samples were dried by heating for 1 min to a temperature approximately 60 "C above the clearing tempera- ture Afterwards the samples were immediately sealed and investigated Transition temperatures were measured using a Mettler FP 82 HT hotstage and control unit in conjunction with a Nikon Optiphot 2 polarising microscope and these were confirmed using differential scanning calorimetry (Perkin Elmer DSC-7) X-Ray studies were performed by means of a Guinier goniometer (Fa Huber) The substances were melted into thin glass capillaries Lyotropic mesophases were studied by the penetration tech- nique A drop of pure amphiphile was surrounded by the solvent between two cover slips The concentration gradient at the amphiphile/solvent boundary allows the phases to develop as bands Their sequence was monitored as a function of temperature In addition, the solvent-saturated samples, obtained by mixing the amphiphile with excess solvent, were investigated by optical microscopy between crossed polarisers The phase structures were determined from the observed textures Etylene glycol and formamide, which were used as solvents, were distilled zn uucuo and stored over molecular sieves Synthesis of diols by Mitsunobu etherificationM with 1,242- isopropylidene functionalised alcohols 4-Dodecyloxy-4-( 3,2-dihydroxypropoxy) biphenyl, la 4'-Dodecyloxybiphenyl-4-01 (1 06 g, 3 0 mmol) and tri-phenylphosphine (1 2 g, 4 5 mmol) were dissolved in dry THF (15 ml) After addition of 1,2-O-isopropylidene glycerine (0 59 g, 4 5 mmol) the mixture was cooled to 0-5 "C At this temperature diethyl azodicarboxylate (0 78 g, 4 5 mmol) was added dropwise over 5min to the stirred mixture, and the solution was stirred for an additional 24 h at room temperature Afterwards the solvent was evaporated and the residue was crystallised twice from methanol-water (9 1) to remove the triphenylphosphine oxide The crude product (0 4 g, 0 8 mmol) was dissolved in wet ethanol (20 ml, containing 5% water) After addition of pyridinium toluene-p-sulfonate (50 mg, 0 2 mmol) the solution was heated at reflux for 3 h Removal of the solvent zn vucuo gave a residue which was dissolved in ethyl acetate (50 ml) and washed with water, saturated aqueous sodium hydrogen carbonate, water and brine successively After drying over sodium sulfate the solvent was evaporated and the residue was repeatedly crystallised from hexane to leave white crystals Yield 0 29 g (23%), transitions/"C K, 142 K, 176 SA 195 I, (MS found 4282908, C27H4004 requires 428 2926), SH (500 MHz, CDCl,, J/Hz) 0 86 (3 H, t, J 7, CH,), 120-1 40 (16 H, m, CH,), 145 (2 H, m, CH,), 1 50-1 70 (2 H, m, OH), 178 (2H, m, CH,), 377 (lH, dd, J 7, 11, CHH,-OH), 3 67 (1 H, dd, J 3, 11, CHbH-OH), 3 96 (2 H, t, J 6, Ar-0-CH,), 403-4 15 (3 H, m, 0-CH,-CCH-OH), 6 93 (4 H, m, Ar-H), 7 43 (4 H, m, Ar-H) 4-Dodecyloxy-4-( 9,1O-dihydroxy-l,4,7-trioxadecyl)biphenyl, lc.Prepared as described for la from 4'-dodecyloxybiphenyl- 4-01 (1 4 g, 4 mmol) and 1,2-O-1sopropylidene-4,7-dioxanon-ane-1,2,9-triol (1 3 g, 6 mmol) Yield 0 26 g (13%), transitions/"C K, 117 K, 122 Sc 136 SA 154 I, (found C, 71 13, H, 928 C31H4806 05H,O requires C, 7082, H, 939%), dH (500 MHz, CDCl,, JIHZ) 0 86 (3 H, t, J 7, CH,), 1 20-1 38 (16H, m, CH,), 145 (2H, m, CH,), 178 (2H, m, CH,), 1 85-2 35 (2 H, br s, OH), 3 54-3 75 (8 H, m, CH,-0), 3 87 (3 H, m, 0-CH,-CCH-OH), 3 98 (2 H, t, J 6, Ar-0-CH,), 1094 J Muter Chem, 1996, 6(7), 1087-1098 4.17 (2 H, m, CH2-O), 6.90-6.98 (4 H, m, Ar-H), 7.44 (4 H, m, Ar-H).4-Dodecyloxy-4-(12,13-dihydroxy-l,4,7,1O-tetraoxatridecyl)-biphenyl, Id. Prepared as described for la from 4'-dodecyloxybiphenyl-4-01 ( 1.06 g, 3 mmol) and 1,2-O-isopro-pylidene-4,7,10-trioxadodecane-1,2,12-triol( 1.18 g, 4.5 mmol).Yield 0.58 g (35%); transitions/"C K 112 S, 121 SA 135 I; (found C, 69.57; H, 9.49. C3,H5,07.0.5 H,O requires: C, 69.56; H, 9.38%); 6H (500 MHz; CDC13; JIHz); 0.86 (3 H, t, J 7, CH3), 1.20-1.38 (16 H, m, CH,), 1.46 (2 H, m, CH,), 1.78 (2 H, m, CH,), 1.95-2.10 (2 H, br s, OH), 3.52-3.76 (12H, m, CH, -0),3.80-3.88 (3 H, m, 0-CH, -CH- OH), 3.97 (2 H, t, J 6, Ar-0-CH,), 4.16 (2H, t, J 5, CH,-0), 6.93 (4H, m, Ar-H), 7.43 (4 H, m, Ar-H). 4-Dodecyloxy-4'-( 5,6-dihydroxyhexyloxy) biphenyl le. Pre-pared as described for la from 4'-dodecyloxybipheny1-4-01 ( 1.06 g, 3 mmol) and 1,2-O-isopropylidenehexane-1,2,6-triol (0.78 g, 4.5 mmol).Yield 0.88g (62 YO);transitions/"C K 134 Sc 157 SA 169 I; 6, (500 MHz; CDC13; J/Hz): 0.87 (3 H, t, J 7, CH,), 1.25-1.83 (26 H, m, CH,), 3.46 (1 H, dd, CHH,-OH), 3.67 (1 H, dd, CHbH-oH), 3.74 (1H, m, CH-OH), 3.95-4.01 (4H, 2t, Ar-0-CH,), 6.92 (4H, 2d, Ar-H), 7.43 (4H, 2d, Ar-H). 2-Pentadecyl-5-[ 4-( 2,3-dihydroxypropoxy) phenyll- 1,3,4- thiadiazole, 2a. Prepared as described for la from 2-( 4-hydroxy- phenyl)-5-pentadecyl-1,3,4-thiadiazole(1.16 g, 3 mmol) and 1,2-O-isopropylidene glycerine (0.59 g, 4.5 mmol). Yield 0.35 g (25%); transitions/"C K, 105 K2 112 S, 114 S, 148 I; (MS: found 462.2891. C26H,203N,S requires 462.29 16); dH (500 MHz; CDC1,; JIHz): 0.86 (3 H, t, J 7, CH3), 1.18-1.38 (22H, m, CH,), 1.42 (2H, m, CH,), 1.70 (2H, m, CH,), 1.85-2.08 (2 H, br s, OH), 3.10 (2 H, t, J 7, CH,-thiadiazole), 3.77 (1 H, dd, J 3, 11, CHH,-OH), 3.87 (1 H, dd, J 3, 11, CH,H-OH), 4.06-4.18 (3 H, m, CH,-CH-OH), 6.98 (2 H, d, J 7, Ar-H), 7.83 (2 H, d, J 7, Ar-H).2-Pentadec yl-5-[4-( 9,l 0-dihydroxy- 1,4,7- trioxadecy1)- phenyl]-l,3,4-thiadiazole, 2c. Prepared as described for la from 2-(4-hydroxyphenyl)-5-pentadecyl-1,3,4-thiadiazole ( 1.1 6 g, 3 mmol) and 1,2-O-isopropylidene-4,7-dioxanonane-1,2,9-triol (1 g, 4.5 mmol). Yield 0.3 g (18%); transitions/"C K, 72 K, 91 Sc 101 SA 119 I; (found: C, 64.77; H, 9.27; N, 5.11; S, 5.93. C30H5005N2S.0.5H20requires C, 64.37; H, 9.18; N, 5.00; S, 5.73%); 6, (500 MHz; CDCl,; JIHz): 0.86 (3 H, t, J 7, CH,), 1.18-1.38 (22H, m, CH,), 1.42 (2H, m, CH,), 1.82 (2H, m, CH,), 2.15-2.36 (2H, br s, OH), 3.12 (2H, t, J 7, CH, -thiadiazole), 3.52-3.78 (8 H, m, CH, -O), 3.80-3.93 (3 H, m, 0-CH,-CH-OH), 4.19 (2 H, t, J 6, Ar-0-CH,), 6.99 (2 H, d, J 7, Ar-H), 7.83 (2 H, d, J 7, Ar-H).2-Pentadecyl-5-[ 4-( 12,13-dihydroxy-l,4,7,1O-tetraoxatri-decyl)phenyl]-1,3,4-thiadiazole 2d. Prepared as described for la from 2-(4-hydroxyphenyl)-5-pentadecyl-1,3,4-thiadiazole (1.16 g, 3 mmol) and 1,2-O-isopropylidene-4,7,lO-trioxadode-cane-1,2,12-triol (1.18 g, 4.5 mmol). Yield 0.2 g (11%); transitions/"C K, 67 K2 84 S, 90 SA 104 I; (found: C, 63.94; H, 9.14; N, 4.77; S, 5.50. C3,H5,06N,S-0.5H,0 requires: C, 63.95; H, 9.18; N, 4.64; S, 5.31%); SH (500 MHz; CDCl3; J/Hz): 0.86 (3 H, t, J 7, CH,), 1.18-1.38 (22 H, m, CH,), 1.42 (2 H, m, CH,), 1.81 (2 H, m, CH,), 1.95-2.30 (2 H, br s, OH), 3.10 (2 H, t, J 7, CH, -thiadiazole), 3.50-3.73 (12 H, m, CH2-O), 3.81-3.90 (3 H, m, 0-CH,-CH-OH), 4.19 (2H, t, J 6, Ar-0-CH,), 6.98 (2H, d, J 7, Ar-H), 7.83 (2 H, d, J 7, Ar-H).4-Decyl-(9,10-dihydroxy-l,4,7-trioxadecyl)benzene 3c. Pre-pared as described for la from 4-decylphenol (1.17 g, 5 mmol) and 1,2-O-isopropylidene-4,7-dioxanonane-1,2,9-triol( 1.65 g, 7.5 mmol). Yield 0.31 g (16%); transitions/"C K 7 SA 60 I; (found: C, 67.52; H, 9.88. C,,H4,0,-0.5H20 requires: C, 68.1 1; H, 10.19%); 8H (500 MHz; CDC13; J/'Hz): 0.85 (3 H, t, J 7, CH,), 1.23 (14 H, m, CH,), 1.53 (2 H, m, CH,), 2.50 (2 H, t, J 7, Ar-CH,), 3.53-3.63 (SH, m, CH,-0), 3.65 (3H, m, CH2-CH-OH), 4.09 (2 H, t, J 5, Ar-0-CH,), 6.81 (2 H, d, J 8, Ar-H), 7.03 (2 H, d, J 8, Ar-H).4-Decyl-(12,13-dihydroxy-l,4,7,10-tetraoxatridecyl)benzene 3d. Prepared as described for la from 4-decylphenol (1.17 g, 5 mmol) and 172-O-isopropylidene-4,7,1 O-trioxadodecane- 1,2,12-triol (2 g, 7.5 mmol). Yield 0.57 g (26%); transitions/"C K 9 SA49 I; (MS: found 440.3125, C25H4406 requires 440.3137); SH (500 MHz; CDC13; JIHz): 0.86 (3 H, t, J 7, CH,), 1.24-1.28 (14 H, m, CHJ, 1.53 (2 H, m, CH,), 2.51 (2 H, t, J 7, Ar-CH,), 3.55-3.72 (12H, m, CH,-0), 3.80-3.86 (3H, m, CH2-CH-OH), 4.09 (2H, t, J 5, Ar-0-CH,), 6.81 (2H, d, J 8, Ar-H), 7.05 (2H, d, J 8, Ar-H). Synthesis of diols via ally1 ethers 2-Pen tadecyl-5-[ 4-( 6,7-dihydroxy-1,Qdioxaheptyl)phenyl 1-1,3,4-thiadiazole 2b.2-Pentadecyl-5-[ 4-( 1,4-dioxahept-6-enyl)- phenyl]-1,3,4-thiadiazole was prepared as described for la by Mitsunobu etherification of 2-( 4-hydroxyphenyl)-5-pentadecyl-1,3,4-thiadiazole (1.16 g, 3 mmol) and 2-allyloxyethanol(l.53 g, 15 mmol). Yield 0.87 g (61%); mp 72 "C; dH (500 MHz; CDCl,; JIHz): 0.86 (3 H, t, J 7, CH,), 1.22-1.44 (24 H, m, CH,), 1.80 (2 H, m, CH,), 3.09 (2 H, t, J 7, CH,-thiadiazole), 3.81 (2 H, t, J 5.2, CH,-0), 4.09-4.19 (2H, m, H,C=CH-CH,-0), 4.18 (2H, t, J 5, CH,-0), 5.20 (lH, dd, J 1.5, 10, H,HbC=CH), 5.30 (1 H, dd, J 1.5, 17, H,HbC=CH), 5.89-5.97 (1 H, m, H,HbC=CH), 6.98 (2 H, d, J 7, Ar-H), 7.84 (2 H, d, J 7, Ar-H). This compound (0.47 g, 1.0 mmol) was added to a solution of N-methylmorpholine N-oxide (0.15 g, 1.5 mmol) in THF (20 ml). To this solution water (0.1 ml) and osmium tetroxide solution (0.05 ml of 1% solution in tert-butyl alcohol) were added.31 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 bisulfite (saturated solution, 5 ml) was added and the resulting slurry was stirred vigorously for 30 min at room temperature. Afterwards the solids were filtered off through a pad of silica gel, the residue was washed twice with ethyl acetate (2 x 50 ml) and the solvents were distilled off using a rotary evaporator. The residue was dissolved in ethyl acetate (50 ml) and the solution was washed three times with water (25 ml) and brine and was finally dried over Na,S04.After evaporation of the solvent the residue was crystallised from hexane-ethyl acetate (10: 1). Yield: 0.41 g (81%); transitions/"C K1 88 K, 97 S, 109 SA 135 I; (found: C, 66.21; H, 9.02; N, 5.40; S, 6.39. C28H4604N2Srequires: C, 66.37; H, 9.15; N, 5.53; S, 6.33%); 6, (500 MHz; CDCl,; J/Hz): 0.86 (3 H, t, J 7, CH3), 1.18-1.38 (22H, m, CH,), 1.44 (2H, m, CH,), 1.83 (2H, m, CH,), 1.86-2.10 (2 H, br s, OH), 3.10 (2 H, t, J 7, CH, -thiadiazole), 3.60-3.75 (4H, m, CH,-0), 3.83-3.91 (3H, m, 0-CH2-CH-OH), 4.19 (2H, t, J 6, Ar-0-CH,), 6.97 (2 H, d, J 7, Ar-H), 7.85 (2 H, d, J 7, Ar-H). 4-Dodecyloxy-4'-(6,7-dihydroxy-1,4-dioxaheptyl)biphenyl, 1b.Prepared as described for 2b from 4'-dodecyloxybiphenyl- 4-01 ( 1.06 g, 3 mmol). Total yield0.3 g (21 YO);transitions/"C K, 124 K2 140 Sx 146 SA 169 I; (found: C, 72.58; H, 9.36. C,,H,,05~0.5H,0 requires: C, 72.31; H, 9.42%); 6, (500 MHz; CDCl,; JIHz): 0.86 (3 H, t, J 7, CH,), 1.18-1.38 (16 H, m, CH,), 1.48 (2 H, m, CH,), 1.40-1.70 (2 H, br s, OH), 1.78 (2 H, m, CH,), 3.62-3.78 (4 H, m, CH2-0), 3.85-3.93 (3 H, J. Muter. Chern., 1996, 6(7), 1087-1098 1095 m, O-CCH2-CCH-OH), 3 97 (2 H, t, J 6, Ar-0-CH,), 4 09 (2H, m, CH2-0), 6 96 (4 H, m, Ar-H), 7 43 (4 H, m, Ar-H) 4Decyl-(6,7-dihydroxy-l,4-dioxaheptyl)benzene, 3b Prepared as described for 2b from 4-decylphenol (1 17 g, 5 mmol) Total yield 0 2 g (1 YO), transitions/"C K 46 S, 69 I, (MS found 352 2607, C21H3604 requires 352 2613), dH (500 MHz, CDCI,, JIHz) 0 86 (3 H, t, J 7, CH3), 1 23 (14 H, m, CH,), 1 53 (2 H, m, CH,), 2 09 (1H, t, J 5, OH), 2 51 (2 H, t, J 7, Ar-CH,), 2 70 (1H, d, J 5, OH), 3 59-3 73 (4 H, m, CH,-0), 385 (3H, m, CH,-CH-OH), 409 (2H, t, J 5, Ar-0-CH,), 681 (2H, d, J 8, Ar-H), 705 (2H, d, J 8, Ar-H) Synthesis of the oligoethylene glycol monoethers 4-Dodecyloxy-4-( 2-hydrox yethox y)biphenyl, 4a 4'-Dodecyl-oxybiphenyl-4-01 (3 54 g, 100 mmol) was dissolved in dry dimethyl formamide (50ml) Potassium carbonate (12 4 g, 90 mmol) and tetrabutylammonium iodide (0 5 g, 3 0 mmol) were added to the solution, followed by addition of 2-bromo- ethanol (1 38 g, 11 mmol) The mixture was then stirred at 70°C for 16 h After cooling to room temperature dichloro- methane (50 ml) was added and the suspension was filtered The solid residue was washed once with dichloromethane (50ml), the solutions were combined and the solvent was distilled off using a rotary evaporator The residue was dis- solved in dichloromethane (100ml) and was washed with two 20 ml portions of dilute hydrochloric acid, water, saturated aqueous sodium hydrogen carbonate and brine, successively, and then dried over sodium sulfate Evaporation of the solvent gave a solid residue, which was recrystallised several times from light petroleum (60-85 "C) and ethyl acetate to give pure 4a Yield 2 3 g (58%), mp 138 "C, (found C, 78 86, H, 9 84 C26H3803 requires C, 78 34, H, 9 62%) 4-Dodecyloxy-4-( 6-hydroxy-1,4-dioxahexyl)biphenyl, 4b 4-Dodecyloxy-4'-( 6-benzyloxy- 1,4-dioxahexyl) biphenyl was pre- pared as described for la from 4'-dodecyloxybipheny1-4-01 (7 08 g, 20 mmol) and 7-phenyl-3,6-dioxaheptanol (3 9 g, 22 mmol) Yield 3 83 g (36%), mp 84 "C, (found C, 78 93, H, 9 10 C35H4804 requires C, 78 89, H, 9 09%), 6, (200 MHz, CDCl,, J/Hz) 0 87 (3 H, t, J 7, CH3), 144 (20 H, m, CH,), 356-410 (10H, m, CH,-0), 450 (2H, s, Ar-CH,-0), 688 (4H, d, J 9, Ar-H), 725 (5 H, m, Ar-H), 734 (4H, d, J 9, Ar-H) This compound was hydrogenated in the presence of 10% palladium on charcoal in 60ml ethyl acetate The catalyst was filtered off and the solvent was evaporated and the residue was repeatedly recrystallised from light petroleum (60-85 "C) to give pure 4b Yield 2 8 g (890/), mp 128 "C, (found C, 76 02, H, 9 62 C28H4204 requires C, 75 97, H, 9 57%) 4-Dodecyloxy-4'-(9-hydroxy-l,4,7-trioxanonyl)biphenyl, 4c 4-Dodecyloxy-4'-( 9- benzyloxy -1,4,7- trioxanonyl )biphenyl was prepared as described for la from 4'-dodecyloxybipheny1-4-01 ( 10 62 g, 30 mmol) and 10-phenyl-3,6,9-trioxadecanol(8 8 g, 33 mmol), Yield 8 3 g (48%), mp 88 "C, (found C, 77 05, H, 9 22 C37H520, requires C, 77 03, H, 9 09 YO),6, (200 MHz, CDCI,, J/Hz) 0 90 (3 H, t, J 7, CH,), 172 (20 H, m, CH2), 3 72 (4 H, m, CH,-0-Ar), 3 88-4 16 (10 H, m, CH2-0), 460 (2 H, s, Ar-CH,-0), 700 (4 H, d, J 9, Ar-H), 7 36 (5 H, m, Ar-H), 7 55 (4 H, d, J 9, Ar-H) The hydrogenation was carried out as as described for the synthesis of 4b Yield 5 9 g 4c (85%), mp 115 "C, (found C, 74 28, H, 9 58 C30H4605 requires C, 74 02, H, 9 53 YO),hH (200 MHz, CDC13, J/Hz) 0 80 (3 H, t, J 7, CH,), 1 22-1 72 (20H, m, CH,), 354-410 (14H, m, CH2-O), 684 (4H, m, Ar-H), 7 36 (4 H, d, J 9, Ar-H), m/z 486 (M+,49%) 1096 J Muter Chern, 1996, 6(7), 1087-1098 4-Dodecyloxy-4'-(12-hydroxy-1,4,7,10-tetraoxadodecyl)-biphenyl 4d 4-Dodecyloxy-4'-(12-benzyloxy-l,4,7,10-tetraox-adodecy1)biphenyl was prepared as described for la from 4'- dodecyloxybiphenyl-4-01 (5 3 g, 15 mmol) and 13-phenyl-3,6,9,12-tetraoxatridecanol(4,8g, 17 mmol) Yield 2 3 g (25%), mp 75 "C, (found C, 75 52, H, 9 13 C39H5606 requires C, 75 43, H, 9 10"/0), 6, (200 MHz, CDCl3, JIHz) 0 84 (3 H, t, J 7, CH,), 118-1 77 (20H, m, CH,), 355-4 13 (18 H, m, CH,-0),454(2H,s,Ar-CH,-0),691(4H,d,J9,Ar-H), 7 31 (5 H, m, Ar-H), 742 (4 H, d, J 9, Ar-H) The catalytic hydrogenation was carried out as described for 4b Yield 1 65 g 4d (83Y0), mp 104 "C, (found C, 72 53, H, 9 63 C32H5006 requires C, 72 41, H, 9 50%), JH (200 MHz, CDCl,, J/Hz) 0 86 (3 H, t, J 7, CH,), 1 20-1 75 (20 H, m, CH,), 33-427(18H,m,CH2-O),693(4H,m,Ar-H),743 (4 H, d, J 9, Ar-H) Preparation of the podands 5 1,3,5-Tris-[ 24 4-dodecyloxybiphenyl-4-yloxy)ethoxymethyll-benzene 5a To a stirred suspension of potassium hydride (008 g, 20mmol), which was washed three times with dry hexane under an argon atmosphere, in dry THF (5 ml) was added 4- dodecyloxy-4-(2-hydroxyethoxy)biphenyl 4a (078 g, 19 mmol) dissolved in dry THF (20 ml) After stirring at room temperature for 2 h a solution of 1,3,5-tris(bromomethyl)benzene(0 21 g, 0 6 mmol) and tetrabutylammonium iodide (007 g, 0 2 mmol) in dry THF (25 ml) was added The mixture was then stirred under reflux for 16 h After cooling to room temperature, the mixture was hydrolysed carefully with 15 ml water and extracted with dichloromethane The organic extract was washed with two 10 ml portions of dilute hydrochloric acid, water, saturated aqueous sodium hydrogen carbonate and brine, successively, and then dried over sodium sulfate Evaporation of the solvent gave a solid residue, which was recrystallised several times from a CHC1,-MeOH (9 1) mixture to give pure 5a Yield 39 mg (5%), mp 180 "C, (found C, 80 27, H, 9 17 C87H,,OO9 requires C, 79 76, H, 9 24%), m/z 1310 (M', 2%) 1,3,5-Tris-[ 1-( 4'-dodecyloxybiphenyl-4-yloxy)-3,6-dioxa-heptyllbenzene, 5b Prepared as described for 5a from 4- dodecyloxy-4'-( 6-hydroxy- 1,4-dioxahexyl) biphenyl 4b (0 88 g, 1 9 mmol) and 1,3,5-tris( bromomethy1)benzene (021 g, 0 6 mmol) Yield 97 mg (12%), transitions/"C K 130 S, 131 I, (found C, 76 85, H, 9 18 C93H132012 requires C, 77 45, H, 9 23%), 6, (200 MHz, CDCI,, J/Hz) 0 76 (9 H, t, J 7, CH,), 1 15-1 66 (60 H, m, CH,), 3 50-4 02 (30 H, m, CH, -0),4 44 (6 H, s, Ar-CH,-0), 680 (12 H, m, Ar-H), 7 12 (3 H, s, Ar-H), 7 32 (12 H, d, J 9, Ar-H), m/z 1440 (M+, 13%) 1,3,5-Tris-[ 1-(4'-dodecyloxybipheny1-4-yloxy)-3,6,9-trioxa-decyllbenzene, 5c Prepared as described for 5a from 4-dodecyloxy-4 -( 9-hydroxy- 1,4,7-trioxanonyl) biphenyl 4c (024 g, 0 5 mmol) and 1,3,5-tris(bromomethyl)benzene (0053g, 0 15 mmol) Yield 23 mg (llY~), mp 12OoC, (found C, 75 04, H, 9 10 C99H144015 requires C, 75 52, H, 9 23%), SH (200 MHz, CDCl,, J/Hz) 0 85 (9 H, t, J 7, CH3), 1 24-1 75 (60H, m, CH,), 362-410 (42H, m, CH,-0), 451 (6H, s, Ar-CH,-0), 690 (12 H, m, Ar-H), 721 (3 H, s, Ar-H), 7 41 (12 H, d, J 9, Ar-H), m/z 1572 (M', 8%) 1,3,5-Tris-[ 1-( 4-dodecyloxybipheny1-4-yloxy)-3,6,9,12-tetraoxatridecyl] benzene 5d Prepared as described for 5a from 4-dodecyloxy-4-( 12-hydroxy- 1,4,7,10-tetraoxadodecyl) biphenyl 4d (0 15 g, 0 28 mmol) and 1,3,5-tris( bromomethy1)- benzene (0 03 g, 0085 mmol) Yield 11 mg (8%), mp 106°C (found C, 73 43, H, 9 10 C,o5H15@18 requires C, 73 89, H, 9 22%), 6, (200 MHz, CDC13, J/Hz) 0 81 (9 H, t, J 7, CH3), 1 17-1 64 (60 H, m, CH,), 3 33-4 29 (54 H, m, CH, -0),4 45 (6H, s, Ar-CH2-0), 684 (12 H, m, Ar-H), 7 16 (3H, s, Ar-H), 7 35 (12 H, d, J 9, Ar-H) Preparation of the 4-dodecyloxy-4'-(o-hydroxyalkoxy)-biphenyls 6 4-Dodecyloxy-4-(3-hydroxypropoxy) biphenyl, 6a Prepared as described for 4a from 4'-dodecyloxybipheny1-4-01 (3 54 g, 10 mmol) and 3-bromopropanol(l 53 g, 11 mmol) Yield 1 5 g (36%), mp 146 "C, (found C, 78 54, H, 9 82 C27H4003 requires C, 78 58, H, 9 78%), 6, (200 MHz, CDCl,, J/Hz) 0 87 (3 H, t, J 7, CH,), 130 (20H, m, CH,), 208 (2H, t, J 7, CH,-CH,--CH,-O), 370-425 (6 H, m, CH,-0), 695 (4 H, d, J 9, Ar-H), 749 (4 H, d, J 9, Ar-H) 4-Dodecyloxy-4-(4-tetrahydropyranyloxybutoxy) biphenyl. Prepared as described for la from 4'-dodecyloxybipheny1-4-01 (3 54 g, 10 mmol) and 4-tetrahydropyranyl-2-yloxybutanol (19 g, 10 mmol) Yield 13 g (BY0), mp llO"C, 6, (200 MHz, CDCI,, J/Hz) 0 85 (3 H, t, J 7, CH,), 1 50 (30 H, m, CH,), 3 35-3 80 (8 H, m, CH,-0), 4 52 (1 H, t, J 3, O-CH-0), 6 90 (4 H, d, J 9, Ar-H), 7 42 (4 H, d, J 9, Ar-H) 4-Dodecyloxy-4'-( 4-hydroxybutoxy) biphenyl 6b 4-Dodecyl-oxy-4 -( 4-tetrahydropyranyloxybutoxy)biphenyl ( 1 3 g, 2 8 mmol) was dissolved in wet ethanol (50ml, containing 5% water) After addition of pyridinium toluene-p-sulfonate (50 mg, 0 2 mmol) the solution was heated at reflux for 3 h Removal of the solvent zn vucuo gave a residue which was dissolved in ethyl acetate (50 ml) and washed with water, saturated aqueous sodium hydrogen carbonate, water, and brine successively After drying over sodium sulfate the solvent was evaporated and the residue was repeatedly crystallised from hexane to leave white crystals Yield 1 06 g (89%) 6b, mp 140"C, 8, (200 MHz, CDCl,, J/Hz) 0 85 (3 H, t, J 7, CH,), 150 (24 H, m, CH, ), 3 38-3 85 (6 H, m, CH,-0), 6 92 (4 H, d, J 9, Ar-H), 7 42 (4 H, d, J 9, Ar-H) 4-Dodecyloxy-4'-( 8-hydroxyoctyloxy) biphenyl 6c Prepared as described for 4a from 4'-dodecyToxybipheny1-4-01(3 54 g, 10 mmol) and 8-bromooctanol (2 3 g, 11 mmol) Yield 1 35 g (BY0), mp 127"C, (found C, 7942, H, 1028 C3,HS0O3 requires C, 79 61, H, 10 45%), 6, (200 MHz, CDCl,, J/Hz) 0 85 (3 H, t, J 7, CH,), 13-1 8 (32 H, m, CH,), 3 63 (2 H, t, J 3, CH2-0), 396 (4H, t, J 3, CH,-0), 692 (4H, d, J 9, Ar-H), 7 43 (4 H, d, J 9, Ar-H) 4-Dodecyloxy-4'-( 1 l-hydroxyundecyloxy) biphenyl 6d Pre-pared as described for 4a from 4'-dodecyloxybipheny1-4-01 (3 54 g, 10 mmol) and ll-bromoundecanol (2 76 g, 11 mmol) Yield 28g (55%), mp 131"C, (found C, 7968, H, 1053 C3sHs603 requires C, 80 09, H, 10 76%), 6, (200 MHz, CDCl,, J/Hz) 088 (3H, t, J 7, CH,), 13-1 8 (38H, m, CH,), 369 (2H, t, J 3, CH2-O), 402 (4H, t, J 3, CH,-0), 698 (4H, d, J 9, Ar-H), 7 49 (4 H, d, J 9, Ar-H) Preparation of the trimesogens 7.l,3,5-Tris[3-(4'-dodecyloxybiphenyl-4-yloxy)propoxy-methyllbenzene, 7a Prepared as described for 5a from 4- dodecyloxy-4 -(3-hydroxypropoxy) biphenyl 6a (0 82 g, 1 9 mmol) and 1,3,5-tris(bromomethyl)benzene (021 g, 0 6 mmol) Yield 97 mg (12%), transitions/"C K 9 Sx 115 SA 133 I, (found C, 79 31, H, 9 18 Cy0H,260y requires C, 79 94, H, 9 4O%), 6, (200 MHz, CDCI,, J/Hz) 0 78 (9 H, t, CH,), 120-1 72 (60H, m, CH,), 201 (6H, t, J 7, CH2-CCH,-CH,-O), 3 55 (6 H, t, CH2-O), 3 88 (6 H, m, Ar-0-CH,), 401 (6H, m, CH,-0), 438 (6H, s, Ar-CH,-0), 684 (12H, d, J 9, Ar-H), 710 (3H, s, J 9, Ar-H), 7 36 (12 H, d, J 9, Ar-H), m/z 1352 (M', 20%) 1,3,5-Tris[4-( 4'-dodecyloxybiphenyl-4-yloxy)butoxymethyll-benzene, 7b Prepared as described for 5a from 4-dodecyloxy- 4'-(4-hydroxybutoxy)biphenyl6b(0 15 g, 0 35 mmol) and 1,3,5- tris(bromomethy1)benzene (0035 g, 0 1 mmol) Yield 15 mg (11?40), transitions/"C K 7 Sx 131 S, 141 I, (found C, 79 86, H, 9 43 C9,HI3,O9 requires C, 80 12, H, 9 55%), 8, (200 MHz, CDCl,, J/Hz) 0 86 (9 H, t, J 7, CH,), 1 24-1 79 (96 H, m, CH,), 3 45 (6 H, m, CH,-O), 3 95 (12 H, t, J 6, Ar-0-CH,), 447 (6H, s, Ar-CH,-0), 690 (12H, d, J 9, Ar-H), 720 (3 H, s, Ar-H), 742 (12 H, d, J 9, Ar-H), m/z 1560 (M', 70%) 1,3,5-Tris[8-( 4'-dodecyloxybiphenyI-4-yloxy)octyloxy-methyllbenzene, 7c Prepared as described for 5a from 4- dodecyloxy-4'-( 8-hydroxyoctyloxy) biphenyl 6c (0 58 g, 12 mmol) and 1,3,5-tris(bromomethyl)benzene (0 13 g, 0 36 mmol) Yield 56 mg (lo%), mp 109 "C, (found C, 80 26, H, 10 15 C,O~H~&, requires C, 80 71, H, 1007%), BH (200 MHz, CDCI,, J/Hz) 0 85 (9 H, t, J 7, CH,), 1 50 (72 H, m, CH,), 338-385 (18H, m, CH,-0), 440 (6H, s, Ar-CH,-0), 6 92 (12 H, d, J 9, Ar-H), 7 18 (3 H, s, Ar-H), 7 42 (12 H, d, J 9, Ar-H) l,3,5-Tris[1 1-( 4'-dodecyloxybiphenyl-4-yloxy)undecyloxy-methyllbenzene 7d Prepared as described for 5a from 4- dodecyloxy-4'-( 1 l-hydroxyundecyloxy) biphenyl 6d ( 1 04 g, 198 mmol) and 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