The MANABIYA Program enables researchers from other institutes, universities, and companies to come to ICReDD for a short-term period of training and joint research. The following paper includes contributions made through the participation of Dr. Sameeta Sahoo from Chandigarh University Uttar Pradesh, India, in the MANABIYA (ACADEMIC) Program. During her stay at ICReDD, she worked with the group of Prof. Yasuhide Inokuma on collaborative research in macrocyclic chemistry.
This paper reports the synthesis of calix[4]thiazole, an elusive macrocycle composed of four thiazole rings, and investigates its structural and coordination properties. Calix[4]thiazole had previously remained unexplored because of the difficulty in constructing an all-thiazole macrocyclic framework. Using the Hantzsch-type thiazole-forming reaction, the researchers successfully isolated calix[4]thiazole and determined its 1,3-alternate structure by single-crystal X-ray diffraction. Protonated forms were also found to adopt different conformations depending on their hydrogen-bonding modes.
Calix[4]thiazole forms 1:1 complexes with Zn2+, Co2+, and Ni2+ ions through coordination by its four thiazole nitrogen atoms. Unlike conventional calix[4]pyrroles, which often coordinate metal ions as anionic ligands after deprotonation, calix[4]thiazole acts as the neutral tetradentate ligand to form cationic metal complexes. Co2+ complex also exhibited amine-binding behavior, demonstrating the potential of calix[4]thiazole for metal-mediated molecular recognition.
These results establish calix[4]thiazole as a new macrocyclic scaffold with coordination properties distinct from those of calix[4]pyrrole. The work may provide new opportunities for the development of metal complexes and molecular recognition systems based on thiazole-containing macrocycles.
This research was published online in Chemical Communications on July 7, 2026.
Article Details
Calix[4]thiazole: an elusive macrocycle with coordination properties
Narendra Nath Pati, Keita Watanabe, Sameeta Sahoo, Yuki Ide, Yasuhide Inokuma
Chemical Communications, 2026, 62, 15280–15284.
DOI: 10.1039/D6CC02980A