Coordination of bromide anions and organic bromine to tryptophan ligands

Two tryptophan-based pyridine dicarboxamide ligands have been synthesised and characterised. 1H NMR studies indicated that these ligands are capable of coordinating to bromide anions through amide/indole NH and CH groups. Based on 1H NMR studies, we found that organic bromides selectively bind to with one of the ligands, as evidenced by complexation induced chemical shifts for the indole and amide NH resonances.