Tin(IV) halide complexes with 5,7-dimethyl-8-quinolinol: structures, optical and thermal properties

Abstract

Three new tin(IV) halide complexes with 5,7-dimethyl-8-quinolinol (dmqo), Sn(dmqo)₂F₂ (1), Sn(dmqo)₂Cl₂ (2a and 2 b), and Sn(dmqo)₂I₂ (3), have been synthesized and characterized by single-crystal X-ray diffraction, UV-Vis spectroscopy, fluorescence, and thermal analysis. The three crystals are of the monoclinic system with space group P2₁/c. A second polymorph of 2 was observed in the space group C2/c. The Sn(IV) center is six coordinate with two bidentate ligands with N and O donor atoms and two halides in a slightly distorted octahedral geometry. The tin(IV) complexes exhibit parallel displaced packing configuration between 5,7-dimethyl-8-quinolinol ligands. Increasing the size of the halide coordinated with the Sn(IV) center increases molecular packing distortion, resulting in weakening π-π interactions between pyridyl rings. Photoluminescence and thermal properties are affected by halide coordination with tin. The relative quantum yields of Sn(dmqo)₂F₂ and Sn(dmqo)₂Cl₂ are higher than that of Sn(dmqo)₂I₂. Complexes 1 and 2 show interesting blue-shifted emissions in the solid state compared to solution. Thermal stability decreases in the order of increasing the size of halide coordinated to Sn(IV).

Graphical Abstract

Keywords:

• Tin halide complex
• Crystal structure
• Intermolecular interactions
• Aggregation blue-shifted emission

Acknowledgement

Authors thank Oliver Baumeyer for photograph images.

Disclosure statement

No potential conflict of interest was reported by the authors.