Synthesis and structure determination of ETS-4 single crystals

We report the hydrothermal synthesis of 10 m 100 m 10 m single crystals of the microporous titanosilicate sodium-ETS-4. The crystallization of large needle-shaped Na-ETS-4 crystals is preceded by the formation and subsequent dissolution of the titanosilicate GTS-1. Large Na-ETS-4 crystals are obtained with purity higher than 97%. The structures of Na-ETS-4 and its Sr ion-exchanged form are solved from single-crystal X-ray diffraction data. It is suggested from the structure solution and further supported by the results of the empirical bond valence model that the bridging unit of ETS-4 contains five-coordinate titanium(IV). Infrared spectroscopy is also used to support the crystallographic results, with regard to the presence of charge-balancing protons and five-coordinate titanium. ETS-4 is, thus, one of only two synthetic titanosilicate materials containing five-coordinate titanium. We also discuss some structural differences between ETS-4 and its natural analogue, zorite.

Nair, S., Jeong, H. K., Chandrasekaran, A., Braunbarth, C. M., Tsapatsis, M., & Kuznicki, S. M.

Nair, S||Jeong, HK||Chandrasekaran, A||Braunbarth, CM||Tsapatsis, M||Kuznicki, SM

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