Two different three-dimensional hydrogen-bonded framework structures in two hydrated adducts meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane--terephthalic acid--water (1/1/4) and (1/1/6)

Abstract

Co-crystallization of meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, C16H36N4, with terephthalic acid (1,4-benzenedicarboxylic acid), C8H6O4, from ethanol yields the tetrahydrate (C16H36N4).(C8H6O4).(H2O)4 (1), meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecaneterephthalic acid-water (1/1/4), while similar co-crystallization from methanol yields the hexahydrate (C16H36N4).(C8H6O4).(H2O)6 (2), meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane-terephthalic acid-water (1/1/6). Both compounds are salts, [C16H38N4]2+.[C8H4O4]2-. 4H2O (1) and [C16H38N4]2+.[C8H4O4]2-.6H2O (2): in (2) both ionic components lie across centres of inversion and in both salts there are two protons held within the N4 cavity of the cation. In the structure of (1), the cations and anions are linked into chains by means of paired N-H...O hydrogen bonds, and the water molecules are linked into continuous chains by means of O--H...O hydrogen bonds, in which each of the H atoms is independently disordered over two equally populated sites. The water chains link the ionic chains into a continuous three-dimensional framework by means of further O-H...O hydrogen bonds. In (2) the cations and anions are linked by single N--H...O hydrogen bonds, again into chains: at the same time the anions and the water molecules are linked by multiple O-H...O hydrogen bonds into continuous two-dimensional nets, which are linked by the cations, by means of N--H...O hydrogen bonds into a three-dimensional framework, entirely different from that in (1).