Synthesis, characterization and mesomorphic behavior of platinum diimine/dithiolate complexes

New transition metal complexes based on 4,4′-bis(substituted)-2,2 ′-bipyridine dichloride and dichalcogenate systems have been synthesized. The substituents employed are single- and double alkyl-chain esters and single-chain amides; the metals used are Pt(II) and Ni(II). The dichalcogenate ligands are 1,2-benzenedithiolates and 1,2-benzenediselenolates. The single crystal X-ray and thermal phase behavior studies of diester derivatives revealed that these complexes possess extensive Pt-Pt interactions in the solid state, while the amide derivative packing is governed by hydrogen bonding.; The longest single-chain diester synthesized exhibits gelating abilities at low concentrations and also shows soft-crystal mesomorphic behavior. Introduction of double-chained diester ligands allowed the first examples of truly liquid crystalline materials based on the diimine/dithiolate transition metal complexes to be synthesized. Investigation of these materials by means of polarized optical microscopy and powder XRD methods characterized them as columnar hexagonal phases. The ability to form liquid crystalline phases in both dichloride and dithiolate compounds depend on the chain length of the diesters employed.; The effect of the dichalcogenate ligand in this system was investigated by substitution of sulfur atoms by the heavier and more polarizable selenium atoms.