Two Novel Rare Earth Coordination Polymers Derived from Zwitterionic 1,3-Bis(1-carboxylatoethyl)imidazolium Bromide: Structures and Magnetic Properties.

• The article we are going to contribute has the following highlights: • Two rare earth metal organic frameworks were synthesized by solvothermal method using zwitterionic 1,3-Bis(1-carboxylatoethyl)imidazolium bromide as ligand. • Complex 2 of Gd(C 9 H 11 N 2 O 4)(C 2 O 4)(H 2 O) (C 9 H 11 N 2 O 4 2‒ = 1,3-Bis(1-carboxylatoethyl) imidazolium ion, C 2 O 4 2- = oxalate) shows antiferromagnetic interactions in the temperature range 2−300 K. Good water-solubility, integrity and stability of 2 significantly different from common complexes grant it great potential in bio-related applications. Two rare earth coordination polymers named {[La 6 (C 9 H 11 N 2 O 4) 11 (H 2 O) 2 (OH) 2 ]⋅Br 5 } n (1) and [Gd(C 9 H 11 N 2 O 4)(C 2 O 4)(H 2 O)] n (2) (C 9 H 11 N 2 O 4 2‒ = 1,3-bis(1-carboxylatoethyl) imidazolium ion, C 2 O 4 2- = oxalate) were solvothermally synthesized using zwitterionic 1,3-bis(1-carboxylatoethyl)imidazolium bromide as ligand. 1 and 2 were both structurally characterized by single crystal X-ray diffraction, and their thermodynamic properties and magnetic properties of 2 were studied. In the 3D structure of 1 , La3+ ions are all ten-coordinated and exhibit three different coordination environments. This 3D structure of 1 is formed by La−O coordination bonds with Br− located in the cavities through H-bond and electrostatic attraction. Different from 1 , all Gd3+ ions in 2 have the same eight-coordinated environment. These two coordination polymers both have good thermostability until 323 °C for 1 and 375 °C for 2 , and then decompose giving rise to La 2 O 3 and Gd 2 O 3 , respectively. The magnetic behaviors of 2 are measured in the temperature range 2–300 K. [Display omitted] [ABSTRACT FROM AUTHOR]