Luminescent 8-hydroxyquinoline derived tin(IV) complexes

Abstract

Four different 8-hydroxyquinoline derivative-based tin(IV) complexes [(nBu)2Sn(Cl-Q-CHO)2] (1), [{(nBu)4Sn2(Q-COO)2}2] (2), [Ph2Sn(Cl)(Q-CHO)] (3) and [Ph2Sn(Cl)(Q-CH{OMe}2)] (4) (Cl-Q-CHO = 5‑chloro-8-hydroxyquinolin-7-carbaldehyde; Q-COO− = 8-hydroxyquinolin-2-carboxylate; Q-CHO = 8-hydroxyquinolin-2-carbaldehyde and Q-CH{OMe}2 = 2-(dimethoxy methyl)quinolin-8-ol) have been synthesized and characterized by elemental analysis, spectroscopy (FT-IR, Mass, UV–Vis, photoluminescence, 1H, 13C and 119Sn NMR) and thermogravimetric analysis. Complexes 1 and 4 have also been characterized by single-crystal diffraction studies and the bulk purity established by powder X-ray diffraction studies. Photophysical studies were conducted in a variety of solvents to demonstrate the effect on excitation and emission on the polarity of the solvent. All the new complexes show higher luminescence in a polar solvent resulting in the stabilization of the excited states. Complex 1 shows a high quantum yield of 97% in chloroform. Further, the photophysical results were substantiated through DFT calculations.