The effect of boronic acid acidity on performance of viologen-based boronic acids in a two-component optical glucose-sensing system

A two-component saccharide sensing system using the fluorescent dye, hydroxypyrene trisulfonic acid, combined with a boronic acid functional viologen as a receptor/quencher in pH 7.4 buffer solution has been further investigated. The effect of substituents on the acidity of the boronic acid was measured. The boronic acid pKa changed in the expected manner when electron donating or withdrawing groups were present. The glucose binding constants were dependent on pKa, but no simple correlation was observed for the Stern–Volmer quenching constants and the fluorescence signal modulation.