Single-crystal to single-crystal transformation from a 1-D chain-like structure to a 2-D coordination polymer on heating

The temperature-driven single-crystal to single-crystal transformation of a new erbium(III) coordination polymer with the ligand benzimidazole-5,6-dicarboxylic acid (H2bidc), {[Er(bidc)(ClO4)((H2O)3]·3H2O}n (1) to [Er(bidc)(ClO4)]n (2), has been reported and the structures of 1 and 2 were determined by X-ray crystallography. The thermal stability of compounds 1 and 2 were studied by thermogravimetric analysis (TGA). Powder X-ray diffraction experiments showed that the phase transitions described for single crystals also occur in the macroscopic powder samples and lead to monophasic products. Interestingly, with the loss of water molecules, the near infrared (NIR) emission of the Er(III) ion in compound 2 can be obviously enhanced compared to that in 1, which provides an effective strategy for enhancing the near infrared luminescence of lanthanide complexes.