Abstract

Anions, or negatively charged molecules, are species found in systems throughout the natural world. However, anion sensing has not been studied to the same degree as cation sensing. Rhenium(I)diimine complexes created by our group employ methods of noncovalent interactions, such as hydrogen bonding, and they demonstrate quenching of phosphorescence upon anionic interaction, as analyzed using fluorimetry and UV-visible spectroscopy. This allows for the quantification of anions by correlating the intensity of emission to concentration with great accuracy. These sensors show high sensitivity towards halides and cyanides, as revealed by substantial emission spectral changes upon addition of low concentrations of anion. Molecular modifications to the bridging ligand of the sensor molecule have been used to study the effects of different electron withdrawing and donating groups to understand the nature of the anion-complex interaction, photophysical mechanisms giving rise to the observed emission changes, and to optimize sensitivity and selectivity of the anion sensor.