A photochromic dinuclear compound: aquatetrakis(μ-2,3-diphenylprop-2-enoato)bis(2,3-diphenylprop-2-enoato)ethanolbis(1,10-phenanthroline)dilanthanum(III).

The title dinuclear complex, (aqua-1κO)tetrakis(μ-2,3-diphenylprop-2-enoato-1:2κ(2)O:O')bis(2,3-diphenylprop-2-enoato)-1κO;2κO-(ethanol-2κO)bis(1,10-phenanthroline)-1κ(2)N,N';2κ(2)N,N'-dilanthanum(III), [La(2)(C(15)H(11)O(2))(6)(C(12)H(8)N(2))(2)(C(2)H(5)OH)(H(2)O)], contains two similar La(III) centres with distorted [LaO(6)N(2)] bicapped triganol-prismatic coordination polyhedra formed by six phenylcinnamate (PCA(-) or 2,3-diphenylprop-2-enoate) ligands, two 1,10-phenanthroline (phen) ligands, a coordinating ethanol molecule and a coordinating water molecule. The two metal centres are bridged by four μ-PCA(-) ligands, with the remaining two PCA(-) ligands coordinated in a monodentate fashion. The noncoordinated carboxylate O atoms on the terminal PCA(-) ligands form O-H···O hydrogen bonds with the coordinated solvent molecules. Each La centre is also coordinated by a bidentate phen ligand. The PCA(-) ligands all adopt syn-syn orientations, with the two phenyl rings presenting dihedral angles of about 70°. The compound displays photochromic behaviour both in solution and in the solid state.