Interfacial charge transfer in a functionalized polyoxotitanate cluster

• A tetratitanium oxide cluster functionalized with catecholate ligands was synthesized.
• Significant ligand-to-metal (LMCT) charge transfer between the sensitizer and the titanium-oxo framework was characterized.
• The charger transfer mechanism was discussed.

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(OiPr)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 π 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.

A tetratitanium oxide cluster functionalized with catecholate ligands was synthesized. The spontaneous charge transfer from the π-orbitals of benzene rings to the Ti3d orbitals is responsible for the visible absorption and the formation of Ti(III) under ambient conditions.Figure optionsDownload as PowerPoint slide