Molecular Tectonics. Hydrogen-Bonded Networks Built from Tetraphenols Derived from Tetraphenylmethane and Tetraphenylsilane

Abstract

Tetrakis(3-hydroxyphenyl)silane (1), tetrakis(4-hydroxyphenyl)methane (2), and tetrakis(4-hydroxyphenyl)silane (3), in which phenolic hydroxyl groups are attached to tetrahedral tetraphenylsilyl and tetraphenylmethyl cores, produce a series of hydrogen-bonded networks when crystallized from CH3COOC2H5. Each hydroxyl group in meta-substituted tetraphenol 1 participates in two intermolecular hydrogen bonds as both donor and acceptor, producing helical chains of hydrogen bonds running along the c axis. Each molecule of tetraphenol 1 is linked to four symmetrically oriented neighbors by a total of eight hydrogen bonds, thereby creating a diamondoid network. No interpenetration is observed, and no significant volume remains for the inclusion of guests. The hydrogen-bonded networks derived from para-substituted analogues 2 and 3 are markedly different. Each molecule of tetraphenol 2 is hydrogen-bonded to six neighboring tetraphenols, and the resulting network defines zigzag channels that run parallel to the c axis, measure about 3.3 × 4.4 Å at the narrowest point, and include CH3COOC2H5 as guest. Approximately 28% of the volume of crystals of tetraphenol 2 is available for inclusion. Tetraphenol 3 crystallizes as a monohydrate, and H2O is incorporated as a structural element in the resulting network. Each molecule of tetraphenol 3 forms hydrogen bonds with two molecules of H2O and four unsymmetrically oriented neighboring molecules of tetraphenol 3, producing a structure that is closely packed. The variety of structures obtained from compounds 1−3 under similar conditions shows that the hydroxyl group of phenols is not a highly predictable director of supramolecular assembly.