An Anthracene-imidazoanthraquinone Conjugate Exhibiting Ratiometric Fluorescence Turn - On Behavior with CN- and F- Anions.

Abstract

A new conjugate, 2-(4-(anthracen-9-yl) phenyl)-[1,2-d]imidazole-1H-anthraquninone (AQI) has been designed and synthesized as a molecular probe 4. The photophysical and electrochemical behavior of the probe in the absence and presence of different class of ions were examined in acetonitrile solution. The probe 4 with F- and CN- anions showed ratiometric fluorescence "turn - On" response due to variation in ICT processes. Cyclic voltammetry of probe exhibited reversible redox behavior wherein the band gap (Eg = 1240/lmax) of probe (DE = 3.220 eV) decreased (~ 2.583 eV) after the interaction with F- and CN- anions. The probe interacted with both anions in a 1:1 stoichiometry with good binding constants (KF- = 2.05×106 M-1 and KCN- = 1.46×106 M-1) and limit of detection/quantification (LOD/LOQ) in nM range. The probable complexes, 4+F-/CN- upon interaction with trifluoroacetic (TFA) acid showed reversible behavior. The out emission of probe upon providing F- and TFA as a chemical inputs mimic the function of a memory device, write-read-erase-read functions and a molecular keypad lock system. The probe upon interaction with both F- and CN- anions showed a naked-eye sensitive color change in solution and on test paper strips. Also, the probe showed sensitivity to detect the F- in toothpaste.