Phenanthroline-Mediated Photoelectrical Enhancement in Calix[4]arene-Functionalized Titanium-Oxo Clusters.

Incorporating two organic ligands with different functionalities into a titanium-oxo cluster entity simultaneously can endow the material with their respective properties and provide synergistic performance enhancement, which is of great significance for enriching the structure and properties of titanium-oxo clusters (TOCs). However, the synthesis of such TOCs is highly challenging. In this work, we successfully synthesized a TBC4A-functionalized TOC, [Ti(TBC4A)(MeO)] (; MeOH = methanol, TBC4A = tert-butylcalix[4]arene). By adjusting the solvent system, we successfully introduced 1,10-phenanthroline (Phen) and prepared TBC4A and Phen co-protected [Ti(TBC4A)(Phen)] (). Moreover, when Phen was replaced with bulky 4,7-diphenyl-1,10-phenanthroline (Bphen), [Ti(TBC4A)(Bphen)] (), which is isostructural with , was obtained, demonstrating the generality of the synthetic method. Remarkably, demonstrates good stability and stronger light absorption, as well as superior photoelectric performance compared to . Density functional theory (DFT) calculations reveal that there exists ligand-to-core charge transfer (LCCT) in , while an unusual ligand-to-ligand charge transfer (LLCT) is present in , accompanied by partial LCCT. Therefore, the superior light absorption and photoelectric properties of are attributed to the existence of the unusual LLCT phenomenon. This study not only deeply explores the influence of Phen on the performance of the material but also provides a reference for the preparation of materials with excellent photoelectric performance.