Light-induced dissolution and concomitant crystallization of a Keggin-type polyoxometalate mimicking a naturally occurring phenomenon

Abstract

A suspension of a yellow polycrystalline compound [PPh₄]₃[PMo^VI₁₂O₄₀] in N-methylformanilide (NMF) (in which it is not soluble), on irradiation with sunlight, initiates dissolution via its reduction followed by its crystallization leading to the isolation of single crystals of compound [PPh₄]₄[PMo^VMo^VI₁₁O₄₀]·3CH₃(C₆H₅)NCHO (1). Compounds [PPh₄]₃[PMo^VI₁₂O₄₀]·1.75 CH₃(C₆H₅)NCHO (2) and [PPh₄]₃[PMo^VI₁₂O₄₀]·2CH₃(C₆H₅)NCHO (3), each containing an oxidized Keggin anion, are obtained at two different temperatures when the corresponding mother liquor is kept in the dark.