Mixed Ligand Coordination Polymers for Metallogelation and Iodine Adsorption

A bis-pyridyl-bis-amide derivative of diphenylmethane (LI) and terephthalate (TA) was combined with a number of metal salts [Cu(II), Zn(II), Ni(II), Co(II), and Cd(II)] in a 1:1:1 molar ratio to generate a series of coordination polymers (CP1A-CP5) which were thoroughly characterized by single crystal X-ray diffraction. All the CPs turned out to be lattice occluded crystalline solids having 4 X 4 grid framework structures. Under suitable conditions, the reactants of the corresponding CPs produced metallogels as envisaged considering a crystal engineering based structural rationale. One of the CPs, namely, CP5, demonstrated the ability to adsorb molecular iodine both in vapor and solution phase. Iodine adsorption was also found to be reversible as evident from its release in ethanol from both CP5@I-2 (vapor) and CP5@I-2 (solution). In situ synthesis of silver nanoparticles was also achieved in the gel matrix of LI without the help of any exogenous reducing agent.