Molecular Tectonics. Hydrogen-Bonded Networks Built from Tetra- and Hexaanilines

Abstract

A series of compounds with multiple PhNH2 groups were synthesized and crystallized, and their structures were solved by X-ray diffraction to assess the ability of -NH2 groups in anilines to direct molecular crystallization. 2,2‘,7,7‘-Tetraamino-9,9‘-spirobi[9H-fluorene] (1c) forms an inclusion complex held together in part by donation of hydrogen bonds from -NH2 groups to guest molecules. Surprisingly, the -NH2 groups do not engage in hydrogen bonding with each other. Tetrakis(4-aminophenyl)methane (2c) crystallizes to form a guest-free close-packed diamondoid network in which each -NH2 group donates and accepts one N−H···N hydrogen bond. Tetrakis[(4-aminophenoxy)methyl]methane (3c), a more flexible analogue, also crystallizes as a close-packed structure maintained by an extensive network of N−H···N hydrogen bonds. Despite the structural similarity of tetraanilines 2c and 3c, their hydrogen-bonding patterns and network topologies are different. A flexible hexaaniline, 1,1‘-oxybis[3-(4-aminophenoxy)-2,2-bi...