Hydrogen-Bonded Dimers of 3,5-Bis(hydroxymethyl)benzoic Acids: Novel Supramolecular Tectons

As a new supramolecular tecton based on hydrogen bonding for crystal engineering, benzoic acid derivatives possessing two hydroxymethyl groups were developed and their crystal structures were investigated by single crystal X-ray analysis. The hydrogen-bonded dimer of the acid which possesses four hydrogen-bonding sites creates two types of networks, a zigzag and a straight hydrogen-bonded network. Zigzag hydrogen-bonded networks were created with methoxy (1) and benzyloxy (2) derivatives. It was found that the ladder structure was created via a straight hydrogen-bonded network when 2 included either methanol or ethanol in its cavity. The introduction of a long alkoxy group (hexyloxy) (3) resulted in the formation of an alternate hydrogen-bonded network. Ethyl benzoate derivative (4) also formed a hydrogen-bonded network in a zigzag manner.