Chiral Ni(II) Coordination Polymers: Structure-Driven Effects of Temperature and Polyvinylpyrrolidone

Chiral Ni­(II) coordination compounds with structures of [NiL­(H2O)3] (1) and {[NiL­(H2O)]·0.5H2O}n (2) (H2L = thiazolidine 2,4-dicaboxlic acid) have been successfully synthesized by the reaction of Ni­(CH3COO)2·4H2O and H2L in aqueous solution at 25 and 80 °C, respectively. From the same procedure with polyvinylpyrrolidone (PVP) as a surfactant, another corresponding micrometer-scale Ni­(II) coordination polymer, {[NiL­(H2O)2]·H2O}n (3), has been obtained at both 25 and 80 °C, which shows a different structure (one-dimensional, 1D) than both 1 (discrete molecule) and 2 (3D). The conversions of structures and conformations are directed by temperature and surfactant (PVP), as confirmed by powder and single-crystal X-ray diffraction. Circular Dichroism (CD) and Second Harmonic Generation (SHG) measurements of the products have been investigated as well, which indicate the potential applications of these products in chiral and nonlinear optical (NLO) areas.