Interfacial charge transfer in a functionalized polyoxotitanate cluster

Understanding the charge transfer processes at the dye/TiO2 interface is often modeled using catechol/TiO2 systems. However, it indeed require precise structural information. In order to simulate the dye/TiO2 systems at a molecular level, herein we report the synthesis and structure of a novel titanium oxo-cluster [Ti4O((OPr)-Pr-i)(6)(DTBC)(4)] (1) functionalized with 3,5-di-tert-butylcatechol (DTBC). UV-Vis spectroscopy, electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations show that 1 exhibits property of Ti(III) which is caused by substantial charge transfer from the pi electrons of the benzene rings to Ti3d orbitals. The present precise structure and charge transfer mechanism help to better understand chromophore binding to semiconductor surfaces and charge transfer at the dye/TiO2 interfaces. (C) 2016 Elsevier B.V. All rights reserved.