Assembly of thiacalix[4]arene-supported high-nuclearity Cd24 cluster with enhanced photocatalytic activity

A high-nuclearity nanoscale Cd-24 cluster has been hydrothermally synthesized by assembly of Cd-4-TC4A (H(4)TC4A = p-tert-butylthiacalix[4]arene) second building units (SBUs) and in situ generated peroxy(mono)phosphate PO53- groups and peroxyphenoxide groups of TC4A. The cluster was structurally characterized by single crystal X-ray diffractions. Photocatalytic studies revealed that the highest nuclearity Cd,S-co-rich Cd-24 cluster exhibits enhanced photocatalytic water splitting activities compared to the sandwich Cd-4(TC4A)(2) (Cd-4) cluster under the same conditions in the absence of a co-catalyst. The nanostructure of Cd-24 incorporated both peroxyphosphate and peroxyphenoxide groups, which increased the metal coordination numbers to give more labile Cd-O/S bonds and is believed to be the key feature that enables the significant photocatalytic water splitting activities.