Application Of Fluorescence And Electrochemical Properties Of Indolizine Compounds

1. The Fluorescence Determination of Nitrite in water samples withIndolizineNitrite widely exists in the soil, natural water and foods and is an important and common pollutant because it is an important precursor of the cancer-leading compond, N-nitrosamine. It can react with the dietary components to form toxic, carcinogenic and/or mutagenic nitrosamines. Thus, the detennination of nitrite is an important project in environment and food analysis and a simple, sensitive and specific detennination of nitrite is highly desirable. In this thesis, a novel fluorescence probe, 3-(4-aminophenyl)indolizine-1-carboxy methyle (API) for the determination of trace nitrite in the aqueous solution has been investigated. It was found that API can form diazo salt with nitrite in acidic medium and then it would form hydroxydiazene in alkaline medium, leading the significant increase in the fluorescence. Based on this reaction, a simple method with high sensitivity and good selectivity for rapid detennination of nitrite was suggested. Using this method, the linear range for the nitrite measurement is 4.5×10^-8-7.5×10^-6mol/L and the detection limit is 8.3×10^-9mol/L(0.38ngmL^-1, S/N=3). Thus, using this method to detect the concentration of nitrite in the aqueous solution, the satisfactory results would be obtained.2. Studies on Interaction of Indolizine-naphthoquinone and CT-DNADeoxyribonucleic acid (DNA) is the essential germ plasm in organisms. DNA is usually the interaction target of many drugs, especially antitumor drugs. Thus, study on the interaction drugs with DNA can understand the mechanism of some diseases at the molecular level, design and synthesize new and efficient drugs. In this thesis, interaction of indolizine-naphthoquinone compounds (INQ) with calf thymus DNA(CT-DNA) was investigated using the electrochemical and spectroscopic methods. It was found that the interaction between INQ and DNA leads the deacrease in the redox peak currents of INQ and the positive shift of the peak positionas well as the decrease in the absorbance of INQ with the increase of CT-DNA concentration. The experimental results suggested that the interaction of INQ with CT-DNA belongs to the intercalative mode. In addition, the intercalative action between INQ and CT-DNA is related to magnitude of the conjugation system in the INQ. Increasing the magnitude of the conjugation system of INQ would intensify the π-π stack interaction between INQ and CT-DNA and then lead the strength of the intercalative action of INQ with CT-DNA. Comparing the interaction of INQ with different polynucleotides with the electrochemical technique, it was found that the interaction of INQ with polynucleotides is of sequence selectivity. The interaction strength of INQ with G-C sequence is larger than that with A-T sequences.