Syntheses, structures, magnetic and fluorescence properties of coordination polymers constructed with the reduced Schiff base carboxylic acid ligand

Abstract

Using a reduced Schiff base carboxylic acid ligand 2-((pyridin-4-ylmethyl)amino)terephthalic acid (H2L), five new coordination polymers (CPs), namely, {[Mn2(L)2(H2O)]·DMF]}n (1), {[Cd(L)(H2O)2]}n (2), {[Cu(L)(H2O)3]·2H2O}n (3), {[Cu(L)(H2O)]}n (4), {[Eu2(L)3(H2O)3(H2O)0.5]·O}n (5) were obtained via different synthesis method and further characterized. Complex 1 is a three-dimensional (3D) framework with a (3, 8)-connected hex topology constructed by binuclear [Mn2N2O9] building unit. In complex 2, the adjacent Cd(II) centers are connected by L2‒ ligands using (κ2)-(κ2)-(κ1)-μ3 coordination pattern to form two-dimensional plane structure. In complex 3, the one-dimensional structures linked by hydrogen bonds (O4‒H7B···O7) to form a 2D supramolecular structure. 4 is a 3D structure and 5 belongs to (3, 5)-connected topology with point symbol of {48·62}. It is worth noting that complexes 1, 3 and 4 show the significant antiferromagnetic interactions indicated that they are potential magnetic materials. Remarkably, compared with H2L ligand, the maximum emission peaks of 2 exhibit varying degrees of blue-shifted, and further study for 2 finds that it can acts as luminescence sensor to selectively detect nitrobenzene (NB).