A Eurium–Organic Polymer Incorporating 1-H, 2-Ethyl-4,5-Imidazole Dicarboxylate, and Formate Ancillary Ligand: Structure, Luminescent, and Magnetic Properties

Abstract

The hydrothermal reaction of eurium(III) salt with substituted imidazole-4, 5-dicarboxylic acid in the presence of aliphatic carboxylate afforded a new lanthanide ploymer, namely, {[Eu₃(Heimda)₄(μ ₂-HCOO)·4H₂O]·2H₂O}_n (1) (H₃eimda = 1H-2-ethyl-4, 5-imidazole-dicarboxylic acid). The polymer 1 features 2-D double-decker networks based on the Ln₄Heimda₄ tetranuclear cluster as secondary building unit. The extensive hydrogen bonds stabilize the crystal structure, forming 3-D supramolecular tectonics. The luminescence spectra of polymer 1 display weak characteristic f-f transfer of Eu(III) ion, besides emission based on the ligand. Variable-temperature magnetic susceptibility measurements show that the end to end bridging fashion of formate results in antiferromagnetic properties occurring between adjacent Eu(III) centers.

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Keywords:

• antiferromagnetic properties
• double-decker network
• lanthanide polymer
• luminescence

Acknowledgments

The authors gratefully acknowledge financial support by the National Natural Science Foundation of China (Nos. 21071074 and 20871042), the Foundation for Backbone Teachers in Universities of Henan Province, China (No. 2012GGJS158), and the Foundation of Education Committee of Henan province, China (No 2011B150022).