Magnetic and Porous Regulation in Cobalt(II) Hydrogen-Bonded Organic Framework via Supramolecular Isomerism
Jing-Yan Zhu, Kusum Kumari, Shijie Chen, Dong Shao, Jiong Yang, Le Shi, Saurabh Kumar Singh, Yuan‐Zhu Zhang
Abstract
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, {[(H 2 O) 2 Co(Hbic) 2 ]·sol} n (H 2 bic = 1 H -benzimidazole-5-carboxylic acid; 1, Sol = 2DMF·1.5H 2 O; 2, Sol = H 2 O), 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 N 2 -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.