Polymeric Complexes with “Piperazine−Pyridine” Building Blocks: Synthesis, Network Structures, and Third-Order Nonlinear Optical Properties

Abstract

A new bidentate “building block”, N,N‘-bis(3-pyridylformyl)piperazine (bpfp), was synthesized. X-ray diffraction studies reveal that the piperazine ring in bpfp forms a chairlike structure conformation. bpfp self-assembled into two-dimensional layered rhombohedral grid polymers {[Mn(H2O)2(SO4)(bpfp)](H2O)3(CH3OH)}n (1) and {[Zn(NCS)2(bpfp)2]·2H2O}n (2) with Mn(II) and Zn(II), a three-dimensional polymer [Cd(N3)2(bpfp)]n (3) with Cd(II), and a one-dimensional zigzag polymer [HgI2(bpfp)]n (4) with Hg(II). Each rhombohedral grid in polymer 1 is composed of four Mn, two bpfp, and two SO42-; the dimensions of the grid are 6.537 × 12.843 A. In polymer 2, each rhombohedral grid consists of 60-membered rings Zn4(bpfp)4 showing the dimensions of 14.231 × 15.586 A. Zn4(bpfp)4 grids are bridged by Zn ions and all pyridyl-N atoms of bpfp ligands into the 2-D network structure along a and c directions. Polymer 3 exhibits a 3-D layered structure with tetragonal prism channel viewing from a direction. The bpfp ligands o...