Types of interaction of meso-tetraphenylporphyrin with alkali and alkaline-earth metal ions

摘要

The cavity in a porphyrin can accommodate metal ions through electron donor-acceptor (EDA) interaction in acetonitrile media without any specially designed fabrication with the porphyrin subunit. Alkali metal ion forms a complex with meso-tetraphenylporphyrin (TP) in 2:1 stoichiometry, while the bivalent Mg ~(2+) ion follows a 1:1 stoichiometry. A fluorescence interaction study indicated that TP can behave like a chemosensor for these ions present in the blood electrolytes. Specifically, for the alkali metal ions intensity-based sensing was observed, due to inhibition of photoinduced electron transfer (PET), entailing enhancement of fluorescence intensity, and for the alkaline-earth Mg ~(2+) a mixed quenching was observed. Na ~+ and K ~+ ions can be differentiated depending upon the extent of fluorescence enhancement.