Bulkiness effect dependent photosalient behaviours of photoactive cadmium coordination polymers

Abstract

Three structurally related cadmium coordination polymers CP₁–CP₃ {[Cd₃(Pebpeb)₂(L₁)₆] (CP₁), [Cd₃(Pebpeb)₂(L₂)₆] (CP₂) and [Cd₆(Pebpeb)₄(L₃)₁₂]·HL₃ (CP₃)} were constructed from the photoactive alkene ligand Pebpeb (Pebpeb = 4,4′-((1E,1′E)-(5-(pyridin-3-ylethynyl)-1,3-phenylene)bis(ethene-2,1-diyl))dipyridine; HL₁ = 3-chlorobenzoic acid; HL₂ = 3-nitrobenzoic acid; HL₃ = 3-isopropyl benzoic acid) and Cd(II) ions in the presence of different auxiliary carboxylic acids. Different conformations of the functional olefinic ligand Pebpeb were observed in CP₁–CP₃ despite their similar 1D chain motif. [2 + 2] Solid-state photodimerization occurred when crystals of CP₁–CP₃ were irradiated with UV light (365 nm) and each displayed different photosalient (PS) responses attributed to the different bulkiness of the auxiliary carboxylic acids employed. A simple photoactuating device was prepared using a CP₁-PVA (PVA = Polyvinyl Alcohol) composite.