Abstract: The mechanism of fluorescence quenching of Tb³⁺-Trion complex by nucleotides,polynucleotides and nucleic acids has been studied.It was considered that it is a static quenching which is based on the phosphate moieties of nucleotides, polynucleotides and nucleic acids conpeting the Tb³⁺ ion with Tiron and forming non-fluorescent binary complex under the optimal conditions.The experimental results of nucleic acids reacting with intercalating reagent of DNAor metal ion using Tb³⁺-Trion complex as a fluorescence probe indicated that the mechanism is reasonable.

Key words: Tb³⁺-Trion complex, Nucleotides, Polynucleotides, Nucleic acids, Mechanisin of fluorescence quenching