Knowledge Bank

Investigation of current ion sensing technology has revealed both the great need for new anion sensors in medicine and environmental science, as well as a number of trends in structural development that can aid in the design of new colorimetric halide indicators for use in aqueous media. Previously, a survey of commercial dyes led the way to a new bromide-sensing design based on the structure of Sudan Black B. Building off of this success, a new approach was taken for the synthesis of iodide detectors from Victoria Blue BO units in a dimeric fashion, incorporating a three-dimensional ion binding site and chromogenic signaling unit in one molecule. Syntheses were attempted for a methylene chain linked dimer through substitution reactions, and a para-phenylene linked dimer through Pd-catalyzed Buchwald-Hartwig coupling. Through promising TLC and prep TLC results were obtained by using methods from Marshall and Lewis, NMR and HPLC-TOF mass spectroscopy revealed that almost no product was formed. Rather, partially due to the heat of the reaction conditions, VB appears to have degraded into three major unknown compounds. Future experiments should strive for more mild reaction conditions when working with VB, as well as better purification methods so that modes of analysis can be properly used.