Two donor-acceptor (D-A) type Zn(II) complexes as fluorescent probes for highly selective detection of iodide
Two D-A type Zn(II) coordination complexes ([Zn2(L1)2(MeCN)(MeOH)]•(MeCN) (1) and [ZnL2(H2O)] (2)) were synthesized from diaminomaleonitrile-based (DMN) Schiff-base ligands (L1 = 2-Amino-3-[(2-hydroxy-naphthalene-1-ylmethylene)-amino]-but-2-enedinitrile, L2 = 2-[(4-chloro-2-hydroxy-benzylidene)-amino]-3-[(2-hydroxy-naphthalene-1-ylmethylene)-amino]-but-2-enedinitrile). Based on the weak blue fluorescence in THF solution and the bright yellow fluorescence in solid state, the ligand L1 shows obvious aggregation induced emission (AIE) in THF-H2O solvent system. The fluorescent emission of complexes 1 and 2 have a significant red-shift relative to the ligand in THF solution. Interestingly, because of aggregation caused by the interaction between L1 and iodide (I-), complexes 1 and 2 exhibit excellent selectivity for fluorescence detecing iodide, and the quenching efficiency of 2 with iodide is higher than 1.