Sensitized photoisomerization of cis-stilbazoliumions intercalated in saponite clay layers

Sensitized photoisomerization of the cis-stilbazolium ion 1 by ruthenium tris-2,2′-bipyridine [Ru(bpy)32+] was studied in saponite clay layers. The reaction yield was 100 times higher than the reaction yield in a homogeneous solution. The Stern–Volmer constant of the luminescence of Ru(bpy)32+ by 1 was 3.4×105 d mol-1, which made the quenching rate constant faster than the diffusion limiting rate. The fast quenching rate implies a static quenching by 1 in the vicinity of Ru(bpy)32+. The reaction efficiency showed a maximum when 70 mol% of 1 was intercalated on the basis of the cation exchange capacity (CEC), where the ruthenium complex and 1 are suitably arranged in the saponite layer for effective photoelectron transfer and subsequent electron relay.