Three-Dimensional Hexagonal Structures from a Novel Self-Complementary Molecular Building Block

Abstract

Nitrilotri(methylphosphonic acid), 1H6, exists as a zwitter ion in its pure form and reveals a complex three-dimensional structure with no predictable structural patterns. However, when acid 1H6 is reacted with 1,7-phenanthroline, 2, 1,10-phenanthroline, 3, acridine, 6, and tripropylamine, 8, in a 1:1 molar ratio, monodeprotonation of 1H6 triggers a prototypal self-complementary 3D hexagonal architecture in complexes 9 (1H5·H·2H2O), 10 (1H5·3H), 11 (1·5H)·(5)0.5, and 12 (1·8H). The networks are stabilized by very strong ionic hydrogen bonds and offer a viable new strategy for the design of stable and predictable 3D open organic networks. However, monodeprotonation of acid 1H6 with quinoline, 6, does not lead to the expected open hexagonal structure in 13 (1·6H) as quinolinium cations cannot effectively fill the void space if open hexagonal open structures were formed. The unique three-dimensional connectivity of these open networks does not permit interweaving, and template effects play a critical role in...