Two dinuclear Zn(II) complexes for the fluorescent detection of 2,4,6-trinitrophenol

In order to obtain high selectivity and high quenching efficiency fluorescent sensors for 2,4,6-trinitrophenol (TNP), a ligand [5-(diethylamino)-2-((quinolin-8-ylimino)methyl)phenol hydrochloride, H2LCl] was obtained by the condensation of 4-(diethylamino)salicylaldehyde and 8-aminoquinoline in the present of HCl; and two Zn(II) complexes, namely [Zn2(μ2-L)(μ2-CH3COO)2Cl] (1) and [Zn2(μ2-L)2(NO3)2] (2), were also prepared via the reaction of H2LCl with Zn(AcO)2·2H2O or Zn(NO3)2·6H2O. 1 (in chloroform) and 2 (in methanol) showed strong emission centered at 498 nm and 540 nm respectively, and both of them displayed superior selectivity and high quenching efficiency to TNP among other nitroaromatics and analogues (i.e., 2,4,6-trinitrotoluene, phenol, nitrobenzene, o-nitrophenol, p-nitrotoluene, m-nitrotoluene, and salicylic acid). 6 equ. of TNP made 92% fluorescence quenching of 1, and 8 equ. of TNP induced 85% quenching of 2. The detection limits for TNP were found to be 0.154 ppm of 1 and 1.01 ppm of 2.