Synthesis and Photophysical Properties of (Cl2Ph)Salen-based Indium Complexes

초록

Herein, to elucidate the effect of substituent electronic properties on the photophysical properties of indium-based organometallic luminophores, we prepare a series of indium complexes (1-5) with salen ligands bridged by an electron-withdrawing 4,5-dichlorophenylene (Cl2Ph) unit. The structures of all the complexes are fully confirmed by(1)H and(13)C NMR spectroscopy as well as elemental analysis. In particular, the molecular structure of3, confirmed by X-ray crystallography, is monomeric and the central indium atom adopts a square-pyramidal geometry. The UV/Vis and fluorescence spectra of1-5show typically salen-centered intramolecular charge transfer transitions with gradual bathochromic shifts as the electron-donating ability of the substituents increases. This feature is further supported by electrochimical studies. Furthermore, the lowest unoccupied molecular orbital energy levels of1-5are considerably lower (approximately -3.70 eV) than those of salen-based indium complexes with other aryl-bridging units owing to the reduced electron-donating effect of the (Cl2Ph)salen group.

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