A bis-pyridyl-bis-amide derivative of diphenylmethane (L1) 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 × 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 L1 without the help of any exogenous reducing agent.

A relatively less explored bis-pyridyl-bis-amide ligand (L1) having a diphenylmethane backbone was exploited to generate a new series of coordination polymers as potential multifunctional materials. The reaction of L1 with ZnCl2, ZnBr2, CuCl2, and CoCl2 resulted in four coordination polymers, namely, CP1 [{Zn­(II)­(μ-L1)­(Cl) 2 }·H 2 O] ∝ , CP2 [{Zn­(II)­(μ-L1)­(Br) 2 }·H 2 O] ∝ , CP3 [{Cu­(II)­(μ-L1) 4 (Cl)}·Cl·H 2 O] ∝ , and CP4 [{Co­(II)­(μ-L1) 4 (Cl) 2 }] ∝ , which were characterized by single-crystal X-ray diffraction. While isomorphic CP1 and CP2 were one-dimensional (1D) coordination polymers displaying a right-handed and left-handed twist, respectively, CP3 displayed a three-dimensional coordination network having open channels that were occupied by chloride counterions and MeOH solvates. CP4, on the other hand, was a 1D looped chain coordination polymer. Both CP1 and CP2 were found to be a good adsorbent of organic dyes with an increased affinity toward anionic dyes. Powder X-ray diffraction studies revealed that the dye adsorption occurred at the surfaces. CP1 was also able to adsorb an anticancer drug, namely, doxorubicin hydrochloride, and deliver it to the target cancer cells MDA-MB-231 as revealed by a cell migration assay and cell imaging studies.

A crystal engineering approach has been invoked to design a new series of eight Zn(II) coordination complexes derived from various non-steroidal anti-inflammatory drugs (NSAIDs), namely diclofenac (DIC), ibuprofen (IBU), naproxen (NAP), flufenamic acid (FLU) and meclofenamic acid (MEC), and two co-ligands, namely N-phenyl-3-pyridylamide (3-Py) and N-phenyl-4-pyridylamide (4-Py), and Zn(NO 3) 2 as potential supramolecular gelators. Half of the coordination complexes thus synthesized were able to form aqueous gels (MG-3-PyMEC, MG-3-PyDIC, MG-4-PyNAP and MG-4-PyMEC). Single crystal structures of all eight complexes revealed that they possessed a gelation-inducing 1D hydrogen-bonded network including amide…amide synthon in some cases, which supported strongly the design principles based on which these complexes were synthesized. Interestingly, one such metallogelator complex, namely 3-PyMEC, showed an intriguing anticancer property against a human breast cancer cell line (MDA-MB-231), as revealed by both MTT and cell migration assays.