Synthesis, Structure, and Light Absorption Behaviors of Prismatic Titanium-Oxo Clusters Containing Lacunary Lindqvist-like Species.

Exploring new structural types of polyoxotitanium clusters (PTCs), especially those containing classical polyoxometalates structures, has always been the focus of research in the field of metal-oxo clusters. In this work, we present the synthesis and characterization of three prismatic PTCs: namely, Ti(μ-O)(μ-O)(OPr)(HOPr)(L1) (; HL1 = 3,5-di--butylcatechol), Ti(μ-O)(μ-O)(OPr)(L2)(L3) (; HL2 = 1-adamantanecarboxylic acid, HL3 = 2-picolinic acid), and Ti(μ-O)(μ-O)(μ-O)(OPr)(L3) (). Single-crystal X-ray diffraction analyses indicate that the construction of these prismatic PTCs is based on a stepwise interlayer assembly of {Ti} and {Ti} substructures. The diameters of their core skeletons are in the range between 0.9 and 1.3 nm. In particular, lacunary Linqvist-like {Ti} and {Ti} building units are found to exist in the structures of and . According to the solid-state UV-vis diffuse reflectance measurements, the absorption band of 3,5-di--butylcatecholate-functionalized shifts toward the visible-light region, giving a smaller optical band gap of 1.56 eV in comparison to (3.36 eV) and (3.25 eV).