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

The reaction between ErCl(3)center dot 6H(2)O and H(2)bmdc (H(2)bmdc = benzimidazole-5,6-dicarboxylic acid) produced two distinct complexes: 1D helical complex {[Er(Hbmdc)(bmdc)(H(2)O)(3)]center dot 3H(2)O}(n) (1) obtained under hydrothermal condition at 160 degrees C and discrete complex [Er(2)(Hbmdc)(2)(bmdc)(2)(H(2)O)(8)]center dot 8H(2)O (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. (C) 2010 Elsevier B.V. All rights reserved.