A novel hexanuclear titanium(iv)-oxo-iminodiacetate cluster with a Ti6O9 core: single-crystal structure and photocatalytic activities

Abstract

A new family of hexanuclear titanium(IV)-oxo-carboxylate cluster K₇H[Ti₆O₉(ida)₆]Cl₂·13H₂O {Ti₆O₉} has been synthesized via the H₂O₂-assisted reaction between TiCl₄ and iminodiacetate ligands. This cluster was fully characterized by single-crystal X-ray diffraction and a wide range of analytical methods, including FT-IR, UV/vis spectroscopy as well as electrochemistry and thermogravimetric analysis. As a new type of carboxylate substituted Ti-oxo-cluster, the structural motif of the {Ti₆O₉} cluster consists of one symmetric {Ti₆O₆} hexagonal prism with two staggered triangular {Ti₃O₃} subunits linked by three μ₂-O bridges. The {Ti₆O₉} polyanions are linked by K⁺ cations to form a novel 3D architecture. The structural information and stability of the {Ti₆O₉} polyanion in aqueous solution were thoroughly investigated by solid-state/solution NMR, ESI-MS spectroscopy. Moreover, this Ti-oxo cluster exhibits remarkable potential as a visible-light homogeneous photocatalyst for degradation of rhodamine B (RhB). Finally, a proposed peroxotitanium(IV)-mediated photocatalytic pathway involved is illustrated by spectroscopic data.