Liquid crystalline guanidinium phenylalkoxybenzoates: towards room temperature liquid crystals via bending of the mesogenic core and the use of triflate counter ions |
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| Authors: | Martin Butschies Johannes Christian Haenle Stefan Tussetschläger |
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| Affiliation: | Institut für Organische Chemie , Universit?t Stuttgart , Stuttgart , Germany |
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| Abstract: | A series of guanidinium salts 1(C n ) m –4(C n ) m ?X bearing phenyl alkoxybenzoate cores have been synthesised and their mesomorphic properties have been investigated by polarising optical microscopy (POM), differential scanning calorimetry (DSC) and powder X-ray diffraction experiments (small-angle X-ray scattering and wide-angle X-ray scattering). While compounds 1(C12)1?X and 3(C12)1?X with one alkoxy chain showed smectic A (SmA) phases irrespective of the counter ion, compounds 1(C12)2?OTf and 3(C12)2?OTf with two alkoxy chains displayed SmA phases and the corresponding chlorides 1(C12)2?Cl and 3(C12)2?Cl displayed Colh. Guanidinium salts 1(C n )3–4(C n )3?X with three alkoxy chains showed Colh phases. Whereas the use of cyclic guanidinium head groups rather than acyclic ones had only a minor influence on the mesophase properties, melting points were significantly decreased by bent core units instead of linear core units. Replacement of chloride counterions by triflate lead to a further depression of the clearing points and shifted the mesophase towards room temperature. |
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| Keywords: | guanidinium ionic liquid crystals triflates room temperature thermal stabilisation |
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