Synthesis, crystal structure, and fluorescent property of a chiral 2D polymer based on bis(2-benzimidazoles) and aromatic carboxylate ligands

We have synthesized a new complex [Zn(H₂C₃PIm)(BTC) H₂O]_n (1) [H₃BTC = 1,3,5-benzenetricarboxylic acid, H₂C₃PIm = 2,2′-(1,3-propanediyl)-bis(1H- benzimidazole)] and determined its structure (C₂₆H₂₀N ₄O₇Zn, Mr = 565.83) using single-crystal X-ray diffraction analysis. The complex crystallizes in the monoclinic system, space group P2(1) with a = 8.497(5), b = 16.316(5), c = 9.316(5) Å, β = 104.955(5), V = 1247.8(11) ų, Z = 2, Dc = 1.506 g·cm^-3, μ(Mo-K_α) = 1.038 mm^-1, F(000) = 580, S = 0.755, the final indices are R = 0.0386 and wR = 0.0456 for 3461 reflections with I > 2σ(I). In the asymmetric unit of complex 1, the distorted tetrahedral Zn^II ion is bridged by the carboxylic oxygen atoms of the BTC ligand and the nitrogen atoms of the H₂C₃PIm ligand. The complex units are linked through BTC ligands into a chiral 2D layer and further connected into a 3D framework by π-π packing interactions between the adjacent H₂C₃PIm ligands. The complex exhibits high stablility in air at ambient temperature and strong photoluminescence at room temperature.