Evolution of nanocrystallinity in periodic mesoporous anatase thin films.

Herein we report the first kinetic study of the intrachannel wall phase-transition of amorphous titania to nanocrystalline anatase for periodic mesoporous titania thin films, monitored by time-resolved in situ high-temperature X-ray diffraction. Structural transformations associated with the phase transition are further probed by high-resolution scanning electron microscopy and transmission electron microscopy. The model found to be most consistent with the kinetic data involves 1D diffusion-controlled growth of nanocrystalline anatase within the spatial confines of the channel walls of the mesostructure. The observation of anisotropic, rod-shaped anatase nanocrystals preferentially aligned along the channel axis implies that the framework of the liquid-crystal-templated mesostructure guides the crystal growth.

Towards flexible inorganic "mesomaterials": one-pot low temperature synthesis of mesostructured nanocrystalline titania.

We hereby report a simple route for the low temperature synthesis of mesoporous nanocrystalline titania involving brief hydrothermal treatment of butanolic precursors and non-ionic tri-block-copolymer surfactant at 100 degrees C, followed by evaporation induced self assembly to make a crack-free flexible film. At no time in the film-forming process is a temperature of more than 120 degrees C reached, thereby permitting the use of substrates that are not stable to higher temperatures.

A Giant Carceplex Permanently Entraps Three Organic Molecules.

Capping a trimer of cavitands at the top and bottom creates a large carceplex which contains three permanently entrapped N,N-dimethylformamide (DMF) molecules (shown schematically). Room-temperature NMR spectra and CPK models indicate that the DMF molecules are free to move within the carceplex cavity and thus create a "microsolvent" environment, while at lower temperatures distinct DMF sites can be distinguished.

Mesoporous bragg stack color tunable sensors.

Herein we report a novel self-assembly synthesis, structural and optical characterization of mesoporous Bragg stacks (MBS) composed of spin-coated multilayer stacks of mesoporous TiO(2) and mesoporous SiO(2). Investigation of the optical response of MBS to the infiltration of alcohols and alkanes into its pores reveals better sensitivity and selectivity than conventional Bragg reflectors. Furthermore, we demonstrate that the chemical sensing ability can be tuned via layer thickness, composition and surface properties.