Eu-phen Bonded Titanium Oxo-Clusters, Precursors for a Facile Preparation of High Luminescent Materials and Films.

Incorporation of Eu complexes into various organic or inorganic matrixes is one of the acceptable strategies to obtain displaying materials having practical applications. In this work, we report a convenient approach to preparing high luminescent organic-inorganic hybrid materials and films from the europium-titanium oxo-clusters (EuTOCs) having photoactive antenna ligands. Three Eu2Ti4 oxo-clusters were synthesized and crystallographically characterized. They are the first reported lanthanide-TOCs coordinated with 1,10-phenanthroline (phen) and 2,2'-bipyridine (bpy) as photoactive ligands, Eu2Ti4O6(phen)2(pa)10 (1) (pa = propionate), Eu2Ti4O6(bpy)2(pa)10 (2), and Eu2Ti4O6(phen)2(MA)10 (3) (MA = methacrylate). Benefitting from the photoactive antenna ligands and the rigid cluster structures, these clusters showed bright red luminescence with quantum yield in the range of 60-80% and long lifetime up to 3.0 ms. Unlike those physically mixed polymeric materials, the MA coordinated compound 3 can be self-polymerized to form a brilliant luminescent film. The film coated slide was used to develop a fluorescence sensor for biomolecule ascorbic acid (AA). The low detection limit and reusable properties suggest great potential for such EuTOC films in real applications.

Molybdenum-titanium oxo-cluster, an efficient electrochemical catalyst for the facile preparation of black titanium dioxide film.

Black-TiO2 has become increasingly interesting as a promising photoactive material. Most of the preparations for black-TiO2 involve either high temperature calcination, plasma, lengthy chemical reactions or dealing with dangerous or toxic chemicals. We found, by accident, that Mo-Ti oxo-clusters are efficient catalysts for the hydrogenation of a TiO2 electrode to black-TiO2 at room temperature. A series of Mo-Ti oxo-clusters, [Ti4Mo4O10(OR)14(X-BA)2] (BA = benzoate, X = H (1), F (2), Cl (3), and Br (4)), were prepared and were characterized by crystallography. They have a Mo4Ti4 structure with Mo(v)-Mo(v) metal-metal interactions. The activated hydrogen (H*) generated by electrochemically catalytic water splitting turns the TiO2 electrode to black-TiO2 at room temperature, due to the reduction of Ti(iv) to H+Ti(iii). The potentials applied for water reduction must generally be higher than the overpotential at the TiO2 electrode (-1.0 V vs. RHE). In this work, the onset potential of hydrogen evolution significantly decreased to -0.1 V vs. RHE. Using this blackened 1-TiO2 electrode, the effective electrochemical catalytic degradation of a dye was examined in comparison with the degradation using the white TiO2 electrode. This work provides a method for the facile preparation of a black-TiO2 film, and is a step forward in black-TiO2 research.

Bio-compatible fluorescent nano TiO materials prepared from titanium-oxo-cluster precursors.

Photoactive nano TiO2 particles with fluorescent properties have attracted great attention because of their potential applications in photodynamic therapy. Herein we report first a simple method to prepare water soluble fluorescent nano titanium oxide particles from titanium-oxo-clusters (TOCs). The nano material was characterized as an aggregate of titanium-oxo-clusters, which can be used directly in aqueous systems for investigations in biomedical fields.

A Series of Ti6 Oxo Clusters Anchored with Arylamine Dyes: Effect of Dye Structures on Photocurrent Responses.

Dye molecules pre-anchored on titanium oxo clusters (dye-TOCs) are attractive as model compounds of dye-sensitized titanium oxide. To investigate the effects of the dye ligand structures of the dye-TOCs on photocurrent conversion, a series of dye-TOCs with the same Ti6 core structure and different antenna ligands (L) was synthesized and characterized crystallographically. The TOCs have the same structural formula of [Ti6 O4 L2 (O3 PPh)2 (OiPr)10 ]. Two types of dyes with para- or meta-substituted structures were designed and used as the ligands. The results show that charge transfer from the donor group to the TiO core of the TOCs with the para-substituted ligands is stronger than those with the meta-substituted ligands. The steric effect of the ligands also greatly influences the photocurrent density. Larger branched structures of the dye ligands reduce the coverage density of the dye-TOCs on TiO2 electrodes and also weaken the effective covalent bonding of the dye-TOCs on the electrode, and consequently, the photocurrent is decreased.