Architectures and fluorescence characteristics of two Cd(II) coordination polymer probes assembled from N-p-toluenesulfonyl-l-glutamic acid

Abstract

By varying the nitrogen-containing auxiliary ligand, two novel cadmium coordination polymers [Cd₂(C₁₂H₁₃NO₆S)₂(C₁₂H₁₂N₂)₂]_n (1), [Cd(C₁₂H₁₃NO₆S)(C₁₀H₈N₂)]_n (2) (C₁₂H₁₅NO₆S = N-p-toluenesulfonyl-l-glutamic acid (H₂tsgluO), C₁₂H₁₂N₂ = 5,5′-dimethyl-2,2′-bipyridyl, C₁₀H₈N₂ = 2,2′-bipyridyl) were satisfactorily assembled under hydrothermal conditions. The crystal structures were confirmed through single-crystal X-ray diffraction analysis and further characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and circular dichroism. Crystal data analysis demonstrates that compounds 1 and 2 possess a one-dimensional (1D) double-chain structure, ultimately compound 1 expands into a three-dimensional (3D) supramolecular architecture through hydrogen bonding interactions and π-π stacking, while compound 2 forms a two-dimensional (2D) layered structure via π-π stacking. The present findings substantiate that a subtle variation in the structure of the N-containing auxiliary ligands can exert a profound influence on the structural motifs of the resultant coordination compounds: circular dichroism spectroscopic studies corroborate the homochiral nature of compound 1, whereas 2 is a non-chiral molecule. Significantly, compounds 1 and 2 exhibit high recognition sensitivities toward Cu²⁺ and Fe³⁺ in aqueous solutions, with low detection limits and excellent anti-interference capabilities, thereby underscoring their potential as fluorescent sensors for the selective detection of copper and iron ions.