AIE active fluorescent probe for the detection of cyanide ion through fluorescence enhancement in real samples: An integrated extensive fluorescence and DFT studies

A simple and easy to synthesize fluorescein hydrazine derivative (FHA) was designed by direct condensation reaction which exhibited remarkable fluorescence properties. Probe FHA exhibited aggregation induced emission (AIE) property in aqueous media and displayed remarkable sensing ability to selectively detect (CN‾) in real samples. Emission intensity of probe FHA was enormously increased on addition of CN− due to the inhibition of cis–trans isomerization across C = N bond in the probe FHA. The probe FHA selectively detected CN− due to its smaller size that easily penetrated into the spaces of FHA. 1H and 13C NMR titration experimentations were carried out to determine the nature of interaction between CN‾@FHA complex. Furthermore, the extensive DFT studies were carried out that includes thermodynamic stability, natural bond orbital (NBO), density of states (DOS), non-covalent interactions (NCIs), frontier molecular orbitals (FMO), and quantum theory of atom in molecule (QTAIM) analysis. All these studies supported the NCIs between CN‾ and FHA.