Lanthanide coordination polymers based on flexible ligands derived from iminodiacetic acid

Two flexible ligands derived from iminodiacetic acid, N-methlyiminodiacetic acid (H(2)mida) and N-(2-hydroxyethyl)iminodiacetic acid (H(2)hida) have been used as ligands towards lanthanide ions. Potentiometric studies (25.0 degrees C, 0.50 mol L-1 Me4NCl) revealed the predominance of stable species at acidic pH values. With this information, the synthesis of the coordination compounds was afforded in aqueous solution and the polymeric solids [Sm(Hmida)(2)(H2O)]ClO4 center dot 1/6NaClO(4)center dot 9H(2)O and [Ln(hida)(H2O)(2)](F3CSO3)center dot H2O (Ln = Ho, Yb) were prepared and characterized. The samarium compound consists of a cationic 2D polymeric structure in which the ligand is protonated in the N atom, preventing coordination to the central atom. The structure presents channels along one crystallographic direction. Ho and Yb coordination compounds are isostructural. A 2D polymeric cationic network is also observed. In this case, the additional hydroxyethyl group and the unprotonated N atom participate in the coordination. (C) 2019 Elsevier Ltd. All rights reserved.