Bandgap Engineering of Titanium-Oxo Clusters: Labile Surface Sites Used for Ligand Substitution and Metal Incorporation

• Published in: Angewandte Chemie International Edition Vol. 55; no. 17; pp. 5160 - 5165
• Main Authors: Liu, Jin-Xiu, Gao, Mei-Yan, Fang, Wei-Hui, Zhang, Lei, Zhang, Jian
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 18.04.2016; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Adsorption; bandgaps; cluster compounds; Clusters; Coordination compounds; Hydrogen production; Ions; labile coordination sites; ligand effects; Ligands; Light effects; Metal ions; Photocatalysis; Reduction (metal working); Robustness; Surface chemistry; Titanium; cluster compounds; labile coordination sites; bandgaps; titanium; ligand effects
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.201510455

Through the labile coordination sites of a robust phosphonate‐stabilized titanium–oxo cluster, 14 O‐donor ligands have been successfully introduced without changing the cluster core. The increasing electron‐withdrawing effect of the organic species allows the gradual reduction of the bandgaps of the {Ti6} complexes. Transition‐metal ions are then incorporated by the use of bifunctional O/N‐donor ligands, organizing these {Ti6} clusters into polymeric structures. The coordination environments of the applied metal ions show significant influence on their visible‐light adsorption. Both the above structural functionalizations also tune the photocatalytic H2 production activities of these clusters. This work provides a systematic bandgap engineering study of titanium–oxo clusters, which is important not only for their future photocatalytic applications, also for the better understanding of the structure–property relationships. Organized titanium clusters: The labile coordination sites of a robust {Ti6} cluster have been used to functionalize the surface of the {Ti6} cluster with organic species and transition‐metal ions (see picture). A bandgap engineering study indicates that both the electron‐withdrawing effect of the organic ligands and the coordination environments of the incorporated metal ions tune the bandgap structures of the titanium–oxo clusters.