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Reactions of titanium dioxide with acetylene molecules have been studied using matrix isolation infrared absorption spectroscopy. The titanium dioxide molecules were prepared by the reactions of laser-ablated titanium atoms with dioxygen. In solid argon, titanium dioxide molecule reacted with acetylene to form the TiO 2 -C 2 H 2 complex spontaneously on annealing. The complex underwent photochemical rearrangement to the OTi(OH)CCH and H 2 Ti(CO) 2 isomers upon UV-visible photolysis. The product absorptions were identified by isotopic substitutions and density functional calculations of isotopic frequencies.

A one-dimensional (1D) piezoelectric BaTiO3(BT) polycrystal with a tetragonal system was controllably prepared using a one-step hydrothermal soft chemical process. A layered H2Ti4O9­·H2O (HTO) single crystal was used as the precursor. Interestingly, the obtained polycrystalline BT constructed from oriented BT nanoparticles shows a set of single-crystalline diffraction points, implying that the BT polycrystal is a mesocrystal. The [010] and [001] directions of the obtained mesocrystalline BT correspond to the [001] and [010] directions of the original HTO crystal, respectively, and the [010] direction of the mesocrystalline BT corresponds to the direction along the length of a 1D rod matrix. An in situ topochemical mesocrystal conversion of mesocrystalline BT grown on the HTO substrate occurred not only on the substrate surface but also in the interlayers owing to the unique TiO6 octahedral layers of HTO. In addition, the piezoelectric response of the 1D mesocrystal was captured for the first time. The piezoelectric property of BT mesocrystals hinges on its nanostructure. It is a challenge to develop a special process to prepare highly 1D anisotropic perovskite titanate polycrystals with high crystallinity and piezoelectric response. This novel strategy can be utilized to develop piezoelectric mesocrystalline materials.