PHOTOPHYSICAL AND PHOTOCHEMICAL PROPERTIES OF 3-DIMENSIONAL METAL-TRIS-OXALATE NETWORK STRUCTURES

Chemical variation and combination of metal ions of different valencie s in the oxalate backbone as well as in the tris-bpy cation of the thr ee-dimensional network structures of the type [M(2)(II)(ox)(3)][M(II)( bpy)(3)] (bpy = 2,2'-bipyridine, ox = C2O42-), [M(I)M(III)(ox>(3)][M(I I)(bpy)(3)] and [M(I)M(III)(ox)(3)][M(III)(bpy)(3)]ClO4 offer unique o pportunities for studying a large variety of photophysical processes. Depending upon the relative energies of the excited states of the chro mophores, excitation energy transfer either from the tris-bipyridine c ation to the oxalate backbone or vice versa is observed, as for instan ce from [Ru(bpy)(3)](2+) as photo-sensitiser to [Cr(ox)(3)](3-) as ene rgy acceptor in the combination [NaCr(ox)(3)][Ru(bpy)(3)], or from [Cr (ox)(3)](3-) to [Cr(bpy)(3)](3+) in [NaCr(ox)(3)][Cr(bpy)(3)]ClO4. In addition efficient energy migration within the oxalate backbone is obs erved. Furthermore, depending upon the excited state redox potentials, light-induced electron transfer processes may be envisaged.