U-Shaped Aromatic Ureadicarboxylic Acids as Versatile Building Blocks: Construction of Ladder and Zigzag Networks and Channels

Abstract

In order to examine versatility of ureadicarboxylic acids as U-shaped building blocks for crystal engineering, their crystal structures and cocrystals with pyridine derivatives were investigated. H-bonding networks created by a sequential linking of H-bonded carboxylic acid dimers resulted in the formation of ladder-type networks in the crystals of N, N ′-diethyl- N, N ′-diphenylureadicarboxylic acid ( 2 ) and N, N ′-diallyl- N, N ′-diphenylureadicarboxylic acid ( 3 ). A zigzag type H-bonding network with wedging of water molecules into carboxy–carboxy H-bonding was observed for N, N ′-dibenzyl- N, N ′-diphenylureadicarboxylic acid ( 4 ). Cocrystals of N, N ′-dimethyl- N, N ′-diphenylureadicarboxylic acid ( 1 ) with 2,5-di(pyridine-4-yl)thiazolo[5,4- d ]thiazole ( 5 ) and 2 with 4,4′-dipyridyl ( 6 ) afforded zigzag-type assembled structures. Two types of channel structures were created in the cocrystals of 1 and dipyridylurea ( 7 ) by inclusion of water molecules together with either methanol or ethanol. The former afforded a straight-type one-dimensional channel, while the latter afforded a fishnet-type two-dimensional channel.