Luminescent and Magnetic Properties of Coordination Polymers Induced by Coordinating Modes of a Bis(oxamate) Ligand.

Abstract

The reactions of an unexploited N,N'-5-carboxyl-1,3-phenylenebis(ethyl oxamate) (HEt2 L) ligand with different Mn2+ and Cd2+ salts under solvothermal conditions afforded four three-dimensional (3D) coordination polymers (CPs): [Mn1.5 L(H2 O)2 ]⋅H2 O (1) [Mn2 L(C2 O4 )0.5 (NMP)(H2 O)] ⋅ NMP (2), [Cd1.5 L(H2 O)2.5 ] ⋅ H2 O (3) and [Cd2 L(C2 O4 )0.5 (H2 O)3 ] ⋅ H2 O (4) (NMP=N-methyl pyrrolidone). L, generated by the in-situ hydrolysis of HEt2 L, displays four kinds of coordinating modes through oxamate and carboxylate groups as well as different syn-syn and syn-trans configurations. The resulting novel (3,4,5)-, (3,4,6)-, (4,5)- and (4,4,4,5)-connected topologies for 1-4 were formed. Among them, 1 has interesting 1D metal-oxamate zigzag chains, 2 contains 1D channels with a free void of 52.5 %, 3 consists of an unprecedented Cd-oxamate layer, 4 has a novel Cd-oxamate-oxalate chain. The antiferromagnetic interactions of 1 and 2 were observed, meanwhile 3 and 4 exhibit solid-state luminescence with the maximum emission bands at 483 and 479 nm, respectively, under an excitation of 332 nm.