Selective fluorescence zinc ion sensing and binding behavior of 4-methyl-2,6-bis(((phenylmethyl)imino)methyl)phenol: Biological application

Zinc ion fluorescence sensing and the binding properties of 4-methyl-2,6-bis(((phenylmethyl)imino)methyl)phenol (HL) have been investigated. It displays high selectivity for Zn2+ and can be used as zinc ion-selective luminescent probe for biological application under physiological conditions. The increase in emission in the presence of Zn2+ is accounted for by the formation of hexanuclear complex [Zn6(L) 2(OH)2(CH3COO)8] characterized by X-ray crystallography. An approximately 6-fold Zn2+-selective chelation-enhanced fluorescence response in HEPES buffer (pH 7.4) is attributed due to the strong coordination of Zn(II) that would impose rigidity and hence decrease the nonradiative decay of the excited state. By incubation of cultured living cells (B16F10 mouse melanoma and A375 human melanoma) with HL, intracellular Zn2+ concentration could be monitored.