The interaction of various anions with artificial receptors is an essential field of research because of the roles played by anions in chemistry, medicine, biology, and the environment. Excess amounts of anions in drinking cause health-related problems, and that in agricultural water causes poor production of crops. For example, nitrate is toxic for infants younger than six months, susceptible to nitrate-induced methemoglobinemia because of its relatively easy oxidation of fetal hemoglobin. Phosphate is a nutrient that causes an increase of phytoplankton in a body of water. Discharging industrial and municipal wastes that contain abundant phosphate may cause eutrophication, resulting in oxygen depletion in the water. Sulfate anion has been of significant concern in nuclear waste management in the USA, interfering in the vitrification process used for waste disposal. Additionally, excessive sulfate in drinking water is related to diarrhea and laxative e_ects. Cyanide is well known as a fast-acting and potentially deadly chemical to humans which poses a severe threat to public health, environment, and homeland security. It is used as a critical reagent in several industries, including gold mining, electroplating, plastic manufacturing, and the petroleum industry, which leads to the unavoidable pollution of the environment. That's why the recognition of anions and purification of water with artificial receptors have immense attention. This research field is being augmented with diverse acyclic and cyclic systems with functional groups urea, thiourea, polyamines, and amides, which can potentially host different anions in solution and solid state. Among the various hosts, macrocyclic polyamines are promising. Because they bind anions by making hydrogen bonds and, after converting them to dinuclear transition metal complexes that can bind anions with Lewis acid-base interaction, which is generally more robust than H-bond interactions. In our research, a polyamines macrocycle was synthesized using 2,6-pyridinedicarboxaldehyde spacers and N-methyl-2,2_-diaminodiethylamine linkage by the Schiff base condensation followed by sodiumborohydride reduction. This polyamines macrocycle was studied for anions (fluoride, chloride, bromide, Iodide, nitrate, perchlorate, sulfate, phosphate, and cyanide) binding by proton NMR spectroscopy technique in solution and single crystal X-ray diffraction method in the solid state. In solution, the protonated receptor showed the highest binding constant for sulfate, and the binding mode was 1:1, as confirmed by the Job plot. Then, the polyamines macrocycle was converted to a dinuclear copper (II) complex, which was investigated for the same anions by calorimetrically and fluorescence technique using commercially available dye disodium eosin Y. Dinuclear copper (II) complex showed the highest binding constant for cyanide by Indicator Displacement Assay. This oral presentation will explain the synthesis, complexation, and anions binding studies in detail.
Acknowledgment: The National Science Foundation is acknowledged for a CAREER award (CHE-1056927) to Dr. Md Alamgir Hossain. The National Institutes of Health (G12MD007581) and RCMI support the analytical core facility at Jackson State University. This work also acknowledges Eastern New Mexico University for supporting Graduate student Mr. Enrique Martinez.