Metal coordination polymers of 2,3-bis(benzimidazol-1-ylmethyl)quinoxaline: Syntheses, crystal structures and luminescent properties

Abstract: Two new metal-organic frameworks, {[CuLI]·CHCl3}∞(1) and {[HgL(Br)2]4·2CH2Cl2}∞ (2) have been prepared by reacting CuI and HgBr2 with the new flexible ligand L [L = 2,3-Bis(benzimidazol-1-ylmethyl)quinoxaline]. Both complexes have been characterized by elemental analysis, IR, TGA, XRPD, and single crystal X-ray diffraction determination. In 1, the Cu(I) ion takes tetrahedral coordination geometry, and the flexible ligands bridge dinuclear units (Cu2I2) to form a one dimensional (1D) double chain structure. While in 2, the Hg(II) coordinates to two bromine ions and two nitrogen donors of L to form a 1D coordination polymer. The structure differences of the two complexes mainly depend on the geometry of the metal ions and the influence of anions. The coordination features of the ligand have also been primarily investigated by density functional theory (DFT) calculations. In addition, the fluorescent properties of the complexes and free ligand L have been investigated in the solid state at room temperature. [Copyright &y& Elsevier]