Abstract:

Two new quaternary ammonium salts of indolizine derivatives 4a(1-{2-[N'-(3-cyano- indolizine-1-carbonyl)-hydrazino]-2-oxo-ethyl}-pyridinium; chloride) and 4b(1-{2-[N'-(3-Cyano-indolizine-1-carbonyl)-hydrazino]-2-oxo-ethyl}-2-methyl-pyridinium; chloride) as fluorescent sensors for Cu²⁺ were synthesized. The structures of the two compounds were determined by IR, ¹H NMR, MS and elemental analysis. Their UV and fluorescence spectra were measured. The influences of sixteen metal ions such as Cu²⁺, Zn²⁺, Ca²⁺, Cr³⁺, Co²⁺, Al³⁺, Mn²⁺, Ni²⁺, Ba²⁺, Hg²⁺, Fe³⁺, Cd^{2 +}, Mg²⁺, Pb²⁺, Li⁺ and Ag⁺ on their fluorescence properties were studied. Spectroscopic studies revealed that the two compounds had rather strong affinity toward Cu²⁺. The specificities of the two probes toward Cu²⁺ were determined. Compound 4a nearly no fluorescence intensity changes were observed in emission spectra together with Zn²⁺, Ca²⁺, Co²⁺, Mn²⁺, Ni²⁺, Ba²⁺, Hg²⁺,Cd²⁺, Mg²⁺, Pb²⁺, Li⁺ and Ag⁺, respectively. Compound 4b nearly no fluorescence intensity changes were observed in emission spectra together with Zn²⁺, Ca²⁺, Cr³⁺, Co²⁺, Al³⁺, Mn²⁺, Ni²⁺, Ba²⁺, Hg²⁺, Cd²⁺, Mg²⁺, Pb²⁺, Li⁺and Ag⁺, respectively. However, under identical conditions, the results showed that compounds 4a and 4b had fluorescence quenching together with Cu²⁺. So we have developed two new fluorescent sensors(4a and 4b). They showed high sensitivity and selectivity toward Cu²⁺ in aqueous solution.

Key words: Quaternary ammonium salt of indolizine derivative, Cu2+ ion, Fluorescent sensor