Temperature-controlled 1D helical and discrete Er(III) complexes based on benzimidazole-5,6-dicarboxylic acid

The reaction between ErCl3·6H2O and H2bmdc (H2bmdc = benzimidazole-5,6-dicarboxylic acid) produced two distinct complexes: 1D helical complex {[Er(Hbmdc)(bmdc)(H2O)3]·3H2O}n (1) obtained under hydrothermal condition at 160 °C and discrete complex [Er2(Hbmdc)2(bmdc)2(H2O)8]·8H2O (2) under ambient temperature, evaporated from the mother liquor of 1. The crystal structures of the complexes were determined by X-ray single-crystal diffraction. Through comparison of complexes 1 and 2, we found that enhanced temperature favors the formation of higher dimensional products and lower amount of coordinated water. Both complexes are characterized by IR, elemental analysis, X-ray powder diffraction and thermogravimetric analysis.

Graphical abstractTwo new coordination compounds were constructed from ErCl3·6H2O and H2bmdc (H2bmdc = Benzimidazole-5,6-dicarboxylic acid). Through comparison of both compounds, it is found that enhanced temperature favors the formation of higher dimensional products and less coordinated water. Both complexes exhibit complicated 3D hydrogen bonding frameworks with multiple π-π stacking interactions.Figure optionsDownload full-size imageDownload as PowerPoint slide