Preparation, Crystal Structure and Enthalpy Change of Formation of the Reaction in Liquid Phase of a New Three-Dimensional Mixed-Ligand Holmium(Ⅲ) Coordination Polymer Based on Strong π-π Stacking Interactions

摘要

A new three-dimensional coordination polymer, [Ho(5-nip)(phen)(NO3)(DMF)] (5-nip=5-nitroisophthalic acid and phen=1,10-phenanthroline), was prepared and characterized by single crystal X-ray diffraction, elemental analysis, IR spectrum and DTG-DSC techniques. The results show that the title complex crystallizes in space group P2/m with a= 1.0906(3) nm, b=1.2804 (3) nm, c= 1.6987(4) nm,β=91.400(5)°, Z=4, Dc= 1.931 Mg/m3, F(000)=1352. Each Ho(Ⅲ) ion is nine-coordinated by one chelating bidentate and two monodentate bridging carboxylate groups, one chelating bidentate NO3- anion, one DMF molecule and one 1,10-phenanthroline molecule. The complex is constructed with one-dimensional ribbons featuring dinuclear units and the one-dimensional ribbons are further assembled into two-dimensional networks by strong π-π stacking interactions with the distance of 0.327 nm,then the networks are arranged into three-dimensional structure according to ABAB fashion. The complex exhibits high stability up to 600 ℃. Its enthalpy change of formation of the reaction in liquid-phase in solvent DMF was measured using an RD496-Ⅲ type microcalorimeter with a value of (-11.016±0.184) kJ·mol-1.