Magnetic and Porous Regulation in Cobalt(II) Hydrogen-Bonded Organic Framework via Supramolecular Isomerism

• Published in: Crystal growth & design 2024-04, Vol.24 (8), p.3449-3457
• Main Authors: Zhu, Jing-Yan, Kumari, Kusum, Chen, Shi-Jie, Shao, Dong, Yang, Jiong, Shi, Le, Singh, Saurabh Kumar, Zhang, Yuan-Zhu
• Format: Article
• Language: English
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.4c00188

Supramolecular isomerism has been recognized as an effective strategy for manipulating structures and properties, particularly in metal–hydrogen-bonded organic frameworks (MHOFs). However, it has been less studied in the context of magnetic dynamics. In this study, we reinvestigated two previously reported cobalt­(II) HOFs, {[(H2O)2Co­(Hbic)2]·sol}n (H2bic = 1H-benzimidazole-5-carboxylic acid; 1, Sol = 2DMF·1.5H2O; 2, Sol = H2O), which exhibit unique supramolecular isomerism. In both complexes, octahedral Co­(II) ions are connected by deprotonated Hbic-ligands to form one-dimensional chains, which are then sustained into three-dimensional frameworks by prominent N–H···O hydrogen-bonding interactions. This results in significantly different porosities and N2-adsorption abilities: a high solvent-accessible void of 46.2% for the desolvated phase of 1, compared to only 2.3% for that of 2, likely due to the additional π–π stacking interactions. Interestingly, our magnetic studies revealed that both 1 and 2 exhibit typical single ion magnet behaviors, with alternating relaxation dynamics (Raman, direct, and QTM for 1; Raman and direct for 2). These findings demonstrate that the structures, stability, porosities, and magnetic properties of MHOF materials can be effectively tuned through a supramolecular isomerization approach.