The Crystal Structures of Three Rhodanine-3-Carboxylic Acids

The rhodanine derivatives show various pharmacological activities. Rhodanine-3-carboxylic acids can be used as the substrates in various synthesis of compounds containing rhodanine-3-carboxyalkyl moiety. In this paper new crystal structures of rhodanine-3-acetic acid and its two homologues, i.e. rhodanine-3-propionic acid and rhodanine-3-butyric acid, are reported. The relationship between the length of the alkyl chain and the geometry of these molecules was studied. The crystal network is dominated by strong hydrogen bonds O–H···O formed by the carboxyl groups. Additionally, weak C–H···O and C–H···S contacts are observed.

To study the difference in intermolecular interactions of rhodanine-3-carboxylic acid, three crystal structures were determined by X-ray diffraction method. The crystal network in all studied structures is built of homosynthons and stabilized by weak C–H···O and C–H···S contacts.