Homochiral imidazole-based dicarboxylate metal complexes with SrSi₂ topology: synthesis, crystal structures, and properties

Abstract

Two new complexes with homochiral frameworks, {Co₃(EIDC)₂(H₂O)₅}_n (1) and {Zn₃(EIDC)₂(H₂O)₄}_n (2) (H₃EIDC = 2-ethyl-1H-imidazole-4,5-dicarboxylic acid), have been synthesized from achiral starting precursors via spontaneous resolution and fully characterized by elemental analyses, IR, circular dichroism, photoluminescence (PL) spectroscopy, single-crystal X-ray diffraction, and thermogravimetric analysis. X-ray diffraction data revealed that 1 and 2 have SrSi₂ topologies and that both are homochiral metal–organic frameworks. Compound 1 is constructed by left-handed chiral chains; however, right-handed chains constitute the homochiral framework of 2. Variable temperature magnetic susceptibility measurements of 1 indicate strong antiferromagnetic interactions between the magnetic Co centers. Compound 2 exhibited weak blue PL in the solid state at room temperature.

Graphical Abstract

Two novel homochiral frameworks with SrSi₂ topology, {Co₃(EIDC)₂(H₂O)₅}_n (1) and {Zn₃(EIDC)₂(H₂O)₄}_n (2) (H₃EIDC = 2-ethyl-1H-imidazole-4,5-dicarboxylic acid), have been synthesized from totally achiral starting precursors via spontaneous resolution. The homochiral natures of 1 and 2 were further confirmed by circular dichroism spectra.

Keywords:

• Homochirality
• Coordination polymer
• Crystal structure
• Fluorescence
• Magnetic property

Funding

This work was supported by the National Natural Science Foundation of China [grant number 21201155]; the Natural Science Young Scholars Foundation of Shanxi Province [grant numbers 2012021007-5, 2013021008-6]; Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi, respectively.