Synthesis, Crystal Structure, and Visible Light Responses of Ti4Cu4-Oxo Clusters with Mixed Valence Copper Ions

Summary of main observation and conclusion In order to extend the absorption spectrum of polyoxo-titanium clusters into the visible region, two new heterometal-oxo clusters Ti 4 Cu II 2 Cu I 2 (μ 3 -O) 6 (benzoate) 10 (MeCN) 4 ( PTC-153 ) and Ti 4 Cu II 2 Cu I 2 (μ 3 -O) 6 (benzoate) 8 (CH 3 COO) 2 (MeCN) 4 ( PTC-154 ) were successfully synthesized. Single-crystal X-ray diffraction and X-ray photoelectron spectroscopy studies showed that these two heterometallic Ti 4 Cu 4 -oxo clusters possessed Chinese knot-shape structure and mixed valence Cu 1+/2+ ions. UV-visible spectroscopy analysis demonstrated that the visible light region absorption of PTC-153 and PTC-154 could be significantly enhanced by doping copper. Furthermore, their visible-light driven photocurrent responses were studied by using samples of PTC-153 and PTC-154 as electrode precursors.