Department of Chemistry and Materials Science, Tokyo Institute of Technology^* Department of Chemistry and Materials Science, Tokyo Institute of Technology, Japan^** Nippon Soda Co., Ltd.^***
○Hidehiro Uekusa^* Naonori Akai^** Natsuki Amanokura^*** Masami Kaneko^***

1,1,2,2-tetrakis (4-hydroxyphenyl) ethane(Fig.1, TEP) is an organic host molecule which crystallizes with guest molecules including organic solvents, and a bactericide, 5-chloro-2-methyl-3(2H)-isothiazolone. The TEP molecule has a unique four arms molecular structure, which has terminal OH group for donating/accepting hydrogen bond and phenyl group for weak hydrogen bond and cavity forming.

Crystal structures of five 1:2 host-guest crystals of TEP with methanol, ethanol, acetone, acetonitrile, and methylacetate were analyzed to investigate the host frameworks and their thermal stabilities. In motif (II) and (III)(Fig.2), the TEP host molecules are connected via terminal OH group and making 1D chain, (II), or 2D net, (III), structures. The guests are hydrogen bonded to the host framework. However, motif (I) takes two guest molecules between hosts to form 1D chain structure.

Thermal analyses of crystals indicate that guest molecules in 2D net (III) are removed easily through solvent channels. The guest molecules in the 1D chain framework (II) are confined in a cavity structure, so the leaving temperature is relatively higher. Thus, the crystal stability is well explained by the types of host framework and hydrogen bonding patterns.