Dialkyl 2,2′-bipyridine-4,4′-dicarboxylate complexes of PtII, CdII and ReI: the effects of metal centre geometry and ligand substitution on phase behaviour

Abstract

Dialkyl 2,2′-bipyridine-4,4′-dicarboxylate derivatives are non-mesogenic ligands capable of supporting liquid crystalline phase formation when coordinated with a variety of metals. Herein is described a preliminary study on altering stable temperature ranges of thermotropic mesophases through metal centre selection and ligand modification. Characterisation of non-mesogenic CdL α n Cl2 complexes and mesogenic ReL α n (CO)3Br and PtL β n Cl2 derivatives are presented (L α n is the ligand with α-attachment of alkyl chains, L β n is the ligand with β-attachment of chains and n is the number of carbons in the alkyl chain). Synthetic procedures and characterisation of the products by differential scanning calorimetry, thermogravimetric analysis, polarising optical microscopy and variable temperature X-ray diffraction are presented.