Cadmium and cobalt oxybis(benzoate) coordination polymers with diverse topologies depending on dipyridylamide ligands including a new self-penetrated network

Abstract

Hydrothermal reaction of cadmium or cobalt nitrate, oxybis(benzoic acid) (obaH2), and a hydrogen-bonding capable dipyridylamide ligand afforded four crystalline coordination polymers whose dimensionality depends critically on the coordination environment or dipyridylamide length. The four new phases were structurally characterized via single-crystal X-ray diffraction. {[Cd(obaH)2(3-pina)2]·2(3-pina)·2H2O}n (1, 3-pina=3-pyridylisonicotinamide) shows 1D chain motifs, while {[Co(oba)(3-pina)]·H2O}n (2) displays closely interdigitated 2D (4,4) grid layer motifs. The longer-spanning dipyridylamide ligand N,N′-(hexane-1,6-diyl)diisonicotinamide (hdin) afforded coordination polymers with more interesting self-penetrated or entangled 3D networks. [Cd(oba)(hdin)]n (3) manifests a unique 4,6-connected 3D self-penetrated network with {426272}(42687283} topology. [Co2(oba)2(hdin)]n (4) exhibits a {Co2(OCO)4} paddlewheel-dimer based 6-connected 3-fold interpenetrated jsm net with 510648 topology. Luminescent behavior in 1 and 3 is attributed to intra-ligand molecular orbital transitions. The new d10 phases were also surveyed for the ability to detect nitrobenzene in ethanol suspension. Thermal decomposition behavior is also discussed herein.