GELS OF BIS[1,2-BIS(3,4-DI-N-ALKOXYPHENYL)ETHANE DIOXIMATO]PALLADIUM(II) COMPLEXES

Bis[1,2-bis(3,4-di-n-alkoxyphenyl)ethanedione dioximato]palladium(II) complexes (abbreviated as [Pd{(CnO)(4)-dpg}(2)]; n = 7-12) form gels i n an over-concentrated n-hexane solution. We have developed a specific cell for X-ray diffraction in order to determine the gel structure. T he gel has a two-dimensional hexagonal structure which is similar to t he inverted hexagonal phase of lyotropic liquid crystals. The electron ic spectra were measured for the gel and for a chloroform solution, wh ich dose not form a gel. As a result, it has become apparent that a 4d z(2)-5pz intermolecular charge-transfer transition between the neighbo ring palladium ions is the main driving force of the gel formation. Th e circular dichroism and magnetic circular dichroism of the gel sugges ted that this complex has a stack of left-handed helicity. The complex also has a thermotropic liquid-crystalline state, as previously repor ted. Hence, these three kinds of states are closely related to each ot her in terms of the formation of molecular aggregates.