Crystal Structures of S-Shaped Phenylenediurea Dibenzoic Acids and Their Cocrystals with Melamine: Unusual Zigzag Tape of H-Bonded Melamine Network

Abstract

Phenylenediurea dibenzoic acid derivatives 1, 2, 3, and 5 and an amide derivative 4 were synthesized, and their molecular structures were elucidated to be an S-shape by single crystal X-ray analysis. Crystals of 1 were obtained as a DMF solvate, while those of 2 and 3 were not. Sheet and ladder structures were created in the crystal packing of 1 and 3, and 2, respectively. Unlike the para-substituted diureas 1–3 which possessed meso-conformation, the meta-substituted diurea 5 exhibited helical-conformation in its crystal structure. The way of crystal packing of 4 is analogous to that of the corresponding dicarboxylic acid derivative 2. A water cluster of a chair-shaped hexagonal array of water molecules was created in the crystal structure of 4. Diureas 1 and 2 gave cocrystals with melamine recrystallized from DMF/ethyl acetate and DMF/H2O, respectively. Unusual zigzag tapes of a H-bonding network of melamine were created in both cocrystals. The zigzag tapes were connected with S-shaped diureas by H-bondi...