Homochiral 1D Zinc−Quitenine Coordination Polymer with a High Dielectric Constant

Heat treatment of a solution of MeOH and water containing the
quitenine ligand HQA [HQA = 6-methoxyl-(8S,9R)-cinchonan-9-ol-3-carboxylic acid] and ZnCl2 at 70 °C to give the one-dimensional
(1D) chain coordination polymer {(HQA)(ZnCl2)(2.5H2O)}n (1). The
local coordination geometry around the zinc center in 1 displays a
slightly distorted tetrahedron, with the HQA ligand adopting a zwitterionic moiety similar to that found in natural amino acids. Measurements on a powdered sample of 1 reveal a strong second-harmonic-generation response of ca. 20 times larger than that for KDP
(KH2PO4). Notably, measurements on the dielectric properties of
1 showed that the 1D chain coordination polymer exhibited a dipolar
chain relaxation process and a high dielectric constant (ε0 = 37.3).