Synthesis, crystal structure and nonlinear optical property of cadmium(II) and copper(II) complexes with novel chiral ligand

Two novel metal-organic frameworks (MOFs) [Cd(3-MPCA)2 · H2O] · 5.5H2O (1) and [Cu(3-MPCA)2 · H2O] · 4H2O (2) [3-MPCA− = (1R, 3S)-1,2,2-trimethyl-3-(pyridin-3-ylmethylcarbamoyl)cyclopentanecarboxylate] were hydrothermally synthesized and characterized by X-ray crystallography. Complexes 1 and 2 are homochiral and have similar one-dimensional (1D) chain structure, which are further linked by strong hydrogen bonds to give 3D architectures. There are oxygen hexmers and heptamers from water molecules and carbonyl group in 1 with O⋯O distances and O–O–O angles comparable to the corresponding values in ice. Nonlinear optical measurements on powdered sample of 1 and 2 revealed that they display second-harmonic-generation (SHG) response of 0.8 and 0.3 times of that for urea, respectively.