Polymorphism in metal complexes of thiazole-4-carboxylic acid

• Main Authors: Meundaeng N., Rujiwatra A., Prior T.
• Format: Journal
• Published: 2017
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84979656159&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/41471
• Institution: Chiang Mai University

© 2016, The Author(s). Five new molecular complexes of chemical formula [M(4-tza) 2 (H 2 O) 2 ] (M = Co, Ni, or Cu) and a complex of [Cu(4-tza) 2 ]·4H 2 O using thiazole-4-carboxylic acid (4-tza) as the ligand have been successfully synthesized and structurally characterized by single crystal X-ray diffraction. Two district polymorphs (α and β) are found for both [Co(4-tza) 2 (H 2 O) 2 ] and [Ni(4-tza) 2 (H 2 O) 2 ]. The effects of solvent composition and temperature on the formation of these polymorphs have been investigated and phase behaviour of the polymorphs was studied through X-ray powder diffraction. Unlike the complexes of Co and Ni, [Cu(4-tza) 2 (H 2 O) 2 ] does not display polymorphism but exhibits irreversible structural transformation from [Cu(4-tza) 2 (H 2 O) 2 ] to the dehydrated form, [Cu(4-tza) 2 ], upon heating.