Novel Alternating Ferro-Ferromagnetic Two-Dimensional (4,4) and Photoluminescent Three-Dimensional Interpenetrating PtS-Type Coordination Networks Constructed from a New Flexible Tripodal Ligand as a Four-Connected Node

Abstract

Two novel two-dimensional (2D) and one three-dimensional (3D) coordination polymers[Ni(HTTG)(H2O)2]n (1), [Co(HTTG)(H2O)2]n (2), and [Cd(HTTG)]n (3)have been hydrothermally synthesized by self-assembly of an unexplored tripodal ligand H3TTG (N,N‘,N‘‘-1,3,5-triazine-2,4,6-triyltris-glycine) and corresponding metal salts. X-ray diffraction analysis reveals that the three polymers exhibit novel frameworks due to diverse coordination conformations and different acid forms of the flexible tricaboxylate ligands. The isostructural complexes 1 and 2 possess 2D frameworks with M(H2O)2(CO2)2 chains bridged by the ligands, and the resulting 3D networks were extended through R22(8) hydrogen bonds between the undeprotonated carboxylate groups and the triazine rings as well as π···π interactions between the triazine rings. Complex 3 shows a 3D interpenetrating compact network with inorganic Cd2O2 chains interconnected by the flexible organic ligands. Topological analysis indicates that in all three complexes the tripodal ligand acts as a four-connected square-planar node, linking four-connected square-planar or tetrahedral-connected metal centers to form interesting two-dimensional (2D) (4,4) (in 1 and 2) and three-dimensional (3D) 2-fold interpenetrating PtS topologies (in 3), respectively. Interestingly, both 1 and 2 exhibit ferromagnetic interactions within the chains bridged by the syn−anti carboxylate groups and the water molecules alternately, and complex 3 displays strong photoluminescent properties at 413 nm due to the coordination of the ligands with the metal centers.