Red-shift in fluorescence emission of D-A type asymmetrical Zn(II) complexes by extending the π-π stacking interaction

Two D-A type asymmetrical Zn(II) coordination complexes, [ZnL1(C2H5OH)] (1) (H2L1 = 2,4-di-tert-butyl-6(( E)-((2-((E)-(2-hydroxybenzylidene) amino)-4-nitrophenyl) imino) methyl) phenol) and [ZnL2(DMF)]center dot DMF (2) (H2L2 = 1-((E)-((2-((E)-(3,5-di-tert-butyl-2-hydroxybenzylidene) amino)-5-nitrophenyl) imino) methyl) naphthalen-2-ol), were designed, synthesized, and studied. Their fluorescence properties were comprehensively analysed based on their single-crystal structures. The results showed that the red-shift of fluorescence emission from complex 1 to complex 2 was successfully pushed via the strategy of extending the p-p stacking interaction.