Four new dinuclear uranyl complexes based on p- and m-toluic acid: Syntheses, structures, luminescent and photocatalytic properties

Four new uranyl complexes, [(UO2)(DMSO)(p-MBA)2]2 (1), [(UO2)(DMSO)(p-MBA)2]2 (2), [(UO2)(DMSO)(m-MBA)2]2 (3) and [(UO2)(Hm-MBA)(m-MBA)2]2 (4) (Hp-MBA = p-toluylic acid, Hm-MBA = m-toluylic acid, DMSO = Dimethyl sulfoxide), were synthesized. Structural analyses reveal that four complexes have similar structures of which two penta-coordinated ((UO2)(ODMSO)(OL)2 in 1–3 and (UO2)(OHL)(OL)2 in 4) uranyl units bridged by two benzoic acid ligands forming dinuclear units. Compounds 1 and 2 belong to two kinds of polymorph forms, C2/c and P 1¯ space groups, respectively. The supramolecular structures of 1–4 are assembled into 3D network by hydrogen bond interactions and π⋯π stacking interactions. Furthermore, the photocatalysis properties of 1 and 2 for degradation of the rhodamine-B (RhB) upon 500 W xenon lamp irradiation have been examined. Elemental analysis, infrared spectroscopy, thermogravimetric analysis, DRS and luminescence properties were also discussed.