Template-Controlled Assembly of Zirconium and Hafnium Clusters Featuring Ligand-Directed Photochemical Performance Modulation

The rational design of molecular metal-oxo clusters provides a versatile strategy for tailoring materials to specific needs at atomic level. Herein, we propose, for the first time and to the best of our knowledge, the concept of templated metal oxo clusters (TMOCs), demonstrated through three zirconium- and hafnium-based mononuclear oxo cluster templates. To achieve enhanced photoelectrochemical performance, we developed customized zirconium and hafnium oxo clusters. Directed assembly of TMOCs with 2,2′-bipyridine enabled effective electron-hole redistribution, resulting in photocurrent responses that increased by approximately 190.9% for Zr oxo clusters and 744.7% for Hf oxo clusters compared to the original TMOCs. A reduction in bandgap of 38.8% and 44.3% was achieved relative to conventional Zr- and Hf-based oxides, respectively. The molecular architecture and photophysical features were confirmed by SCXRD, FT-IR, UV-vis absorption, diffuse reflectance spectroscopy, and electrochemical studies. TD-DFT and DFT calculations provided theoretical guidance for the design of template molecules and revealed the mechanistic basis for the significant enhancement in photoelectrochemical performance. By employing ligand-directed strategies to fine-tune the electronic structures of Zr and Hf oxo clusters, the photoelectrochemical performance of TMOCs based clusters were significantly enhanced. This study establishes a novel templated approach for the design of molecular materials and provides molecular-level insights for the rapid development of functionalized materials.