A Comparative Study on “Turn-off” Fluorimetric Nitro Aromatic Detection Using a Class of Dinulear Zinc (II) Schiff Base Complexes

Four “end-off” compartmental ligands 2,6-bis((E)-((2-(dimethylamino)ethyl)imino)methyl)-4-R-phenol, where R= methyl/isopropyl/ tertiary butyl/ chloro for HL1 – HL4 respectively, have been designed and four complexes of zinc(II) have been synthesized and structurally characterized with the aim to apply them as nitro aromatic detector by utilizing their fluorescent behavior. All the four complexes are found to be highly fluorescent in acetonitrile medium and their emission intensities are found to quench in presence of four nitro aromatics such as 2,6-dinitrotoluene (2,6-DNT), 4-nitrobenzoic acid (4- NBA), 1,3-dinitrobenzene (1,3-DNB), and 4-nitrotoluene (4-NT) with the complex 4 having the highest quenching capability. Fluorescence sensing ability and anti interference ability were done using complex 4 and 4-NBA to establish their exclusive detection property. Stern-Volmer experiments were performed to evaluate the quenching constants. Finally, photo physical experiments such as temperature dependent fluorescence titration study and TCSPC experiment in presence of quencher are carried out to prove the quenching mode as a dynamic.