Co(II) and Mn(II) coordination polymers: Ligand functional and positional isomeric effects, structural diversities, luminescence sensing and magnetic properties

Abstract

Two new isostructural 3D Co(II) and Mn(II) coordination polymers (CPs) [M(L1′)2] (M = Co(1) and Mn (2)) were prepared by reactions of metal salts and 2-connected 4-(4-(3-cyanophenyl)-[2,3′-bipyridin]-6-yl)benzoic acid ligand (HL1′). Interestingly, when simple modification of the ligand functional group (from the cyano to carboxylate group), other two new 3D Co(II) [Co(HL2′)2] (3) and Mn(II) [Mn(L2′)(H2O)] (4) CPs are constructed by using 3-connected 3-(6-(4-carboxyphenyl)-[2,3′-bipyridin]-4-yl) benzoic acid (H2L2′), which are ascribed to the change in ligand functionality (from the cyano to carboxylate group). Moreover, the variable positions of cyano group (or carboxylate group) at the ligand isomers also can tune structural diversities. Present and previous works indicate that the isomeric effects of the ligand isomers play important role in adjusting structures of the Co(II) CPs. 1–4 were fully characterized by IR, elemental analyses, TGA, PXRD, and single-crystal X-ray diffraction. Interestingly, 2 and 4 can serve as sensing materials for detecting Fe3+ and Cr2O72− ions. Furthermore, the magnetic properties of four CPs have been investigated. The present work provides a promising approach to design and construct CPs or MOFs by adjusting ligand functionality and positional isomeric effects.