An "end-off"-type compartmental Lewis base, 2,6-bis(2-hydroxybenzyl-2-hydroxyethylamino)methyl-4-methylphenol (L), was synthesized as a potential chemosensor for Zn2+ ions. L coordinates two Zn2+ cations in methanol-water solution, forming a dinuclear complex whose formulation was confirmed by ESI-MS spectroscopy and Job's plot. The fluorescence of L is remarkably enhanced by Zn2+ as compared with K+, Ca2+, Mg2+, Cu2+, Pb2+, Mn2+, Fe3+, Fe2+, Co2+, Cd2+ and Ni2+ ions. The fluorescence enhancement is attributed to the complexation of Zn2+ with L, which interrupts the photoinduced electron transfer process and rigidifies the molecular skeleton of L. The fluorescence of L is greatly dependent on the acidity and polarity of the solvents. This compound may be used as a probe to sense Zn2+ ion in polar protic solvents after proper modification.
chemosensor; fluorescence mechanism; phenol derivative; solvent effects; zinc(II)
