Structural Analysis of Selenium Coordination Compounds and Mesoporous TiO₂-Based Photocatalysts for Hydrogen Generation

This study reports the synthesis of ten coordination compounds (<b>1</b>-<b>10</b>) derived from the ligand bis((3-aminopyridin-2-yl)selanyl)methane (<b>L</b>) and different metal centers (Co^II, Cu^I, Cu^II, Zn^II, and Ag^I). Single crystals of the complexes were obtained via slow diffusion from overlaid solutions of ligand <b>L</b> and the corresponding metal. Their crystalline structures were determined by single-crystal X-ray diffraction (SCXRD) and further characterized using spectroscopic, spectrometric, and voltammetric techniques. Complexes <b>1</b>-<b>5</b>, <b>7</b>, and <b>10</b> were evaluated as cocatalysts of mesoporous titanium dioxide (m-TiO₂) for photocatalytic hydrogen production via water photolysis under solar light simulation, using triethanolamine (TEOA) as the sacrificial agent. The results showed that complexes <b>4</b>, <b>5</b>, <b>7</b>, and <b>10</b> enhanced m-TiO₂ photocatalytic activity, achieving hydrogen evolution rates at least four times higher than standard m-TiO₂ and P25. Among these, the photocatalyst m-TiO₂-<b>7</b> (<b>7</b> = [Cu₂(μ-SO₄)₂<b>L</b>_<b>2</b>]) exhibited the highest hydrogen production, reaching approximately 7800 μmol/g over a 6-h experiment-nearly 26 times greater than pure m-TiO₂ (300 μmol/g). These findings highlight the potential of organoselenium metal complexes for the development of novel photocatalytic materials based on nonprecious metals.