Synthesis and crystal structure of a new nickel(II) coordination polymer based on Schiff base

A new Schiff base coordination polymer, [Ni(C₁₈H₁₆N₃O₂)₂ · 2CH₃OH] _n (C₁₈H₁₆N₃O₂, 2-acetylpyridine-L-tryptophan), was synthesized and characterized by IR, UV, and X-ray diffraction singlecrystal analysis. The crystal crystallizes in the tetragonal crystal system, space group P4₃2₁2 with cell parameters a = 11.8912(11), c = 28.822(3) ?, V = 4075.5(6) ?³, Z = 4, F(000) = 1544, S = 1.187, ??_calcd = 1.199 g cm^?3, ?? = 0.525 mm^?1, the final R ₁ = 0.0515 and wR ₂ = 0.1513 for 3602 observed reflections (I > 2??(I)). The Ni(II) atom is six-coordinated by two nitrogen atoms from C=N, two nitrogen atoms from pyridine rings and two carboxylic oxygen atoms in different ligands, forming a distorted octahedron geometry. Each ligand serves as a bridging ligand to link Ni²⁺ ions through carboxylic oxygen atoms, leading to a two-dimensional coordination polymer.