Affinity Studies of Hemicyanine Derived Water Soluble Colorimetric Probes with Reactive Oxygen/Nitrogen/Sulfur Species

Abstract

AbstractPeroxynitrite (ONOO‐) is an essential endogenous reactive oxygen species (ROS) generated in mitochondria under various pathological and physiological conditions. An increase in its level in mitochondria is related to numerous diseases. Herein, we report a series of hemicyanine‐derived water‐soluble colorimetric probes (1–4) and the reactivity of which was studied with various reactive oxygen, nitrogen, and sulfur species. Probes 1–4 are formed by conjugating 1,2,3,3‐tetramethyl‐3H‐indolium iodide and 4‐hydroxybenzaldehyde or its derivatives through an alkene linkage formed by the Knoevenagel reaction. Oxidative cleavage of the electron‐rich double bond of the conjugated hemicyanine dye revealed a discerning affinity of probe 3 towards peroxynitrite among all reactive oxygen species. The rapid change in color of 3 provides a sensitive and selective method for detecting peroxynitrite with a low detection limit of 180 nM. Notably, the water solubility of the probe displays excellent performance for the selective detection of peroxynitrite among ROS and reactive nitrogen (RNS)/sulfur species (RSS). UV‐vis, 1H NMR, and 13C NMR spectroscopic data and results from theoretical calculations provide further information on the interaction of peroxynitrite with probe 3.