Spectroscopic and Colorimetric Studies for Anions with a New Urea-Based Molecular Cleft

A new simple urea-based dipodal molecular cleft (L) has been synthesized and studied for its binding affinity for a variety of anions by H-1-NMR, UV-Vis and colorimetric techniques in DMSO-d(6) and DMSO, respectively. The results from titration studies suggest that the receptor forms a 1:2 complex with each of the anions used via hydrogen bonding interactions and exhibits strong selectivity for fluoride among halides, showing the binding affinity in the order of fluoride > chloride > bromide > iodide; meanwhile, it displays moderate selectivity for acetate among oxoanions, showing the binding affinity in the order of acetate > dihydrogen phosphate > bicarbonate > hydrogen sulfate > nitrate. Colorimetric studies of L for anions in DMSO reveal that the receptor is capable of detecting fluoride, acetate, bicarbonate and dihydrogen phosphate, displaying a visible color change in the presence of the respective anions.

Automated summary

A new simple urea-based dipodal molecular cleft has been synthesized and studied for its binding affinity for various anions. The receptor shows strong selectivity for fluoride among halides and moderate selectivity for acetate among oxoanions, displaying visible color changes in the presence of specific anions.