Preparation, crystal structures and properties of a series of novel lanthanide complexes based on 2,3-dimethoxybenzoic acid and 1,10-phenanthroline

Abstract

Ten novel lanthanide complexes {[Ln(L)3phen][Ln(L)3phen (C2H5OH)(H2O)]}2 (Ln=La (1), Nd (2)) and [Ln(L)3phen]2 (Ln=Pr (3), Sm (4), Eu (5), Gd (6), Tb (7), Dy (8), Ho (9), Er (10); HL: 2,3-dimethoxybenzoic acid; phen: 1,10-phenanthroline) have been synthesized and characterized by elemental analyses, IR spectra and powder X-ray diffraction. Single crystals of complexes 1–5 and 8 were obtained and their structures have been determined by single crystal X-ray diffraction. The molecular structures of complexes 1 and 2 are very particular. They both contain two structures with different coordination environments but the same geometric configurations in the molecular structures, which has rarely been reported previously. Complexes 3, 4, 5 and 8 have similar structures with coordination numbers of nine, forming distorted monocapped square antiprisms, and their binuclear structures are stitched together by π–π intermolecular interactions to form 1D chains. The thermal decomposition mechanisms of complexes 1–10 have been studied by the technology of TG and TG-FTIR. The antimicrobial activities of the ten complexes have been explored by the disc diffusion method. The solid-state luminescence of complexes 5 and 7 was also studied, and the two complexes exhibit strong fluorescence, which shows that phen has a better sensitizing effect.