Synthesis And Application Of A Fluorescent [2] Rotaxane And Chemsensors Based On A Rhodamine B Unite

Rhodamine B is a kind of xanthene fluorescent dye, which having a conjugated structure and rigid planar. With its superior photophysical properties and biocompatibility, it has become a good material for fluorescent probe and has a very good value in the field of medical diagnostics. In addition, rhodamine B, which has the large steric structure and functional groups, has become an important material in the field of supramolecular chemistry, especially the application in terms of rotaxane. Since 1976, the crown ether complexation with metal ions have been extensively studied by scientists and has been used in environmental science, materials science, life sciences and other fields.In the first part of this dissertation, the design, synthesis and application of two novel fluorescent probes based on rhodamine B were studied. Probe A exhibits a high selectivity for Fe3+ in the presence of many other metal cations in a MeOH/H2O (1:1, v/v, pH= 7.4) solution. The binding analysis using a Job plot suggested that probe A formed a 1:1 complex with Fe3+, and the binding association constant for Fe3+, Ka, was estimated to be 2.46×104M-1. The detection limit was then calculated to be 0.396 μM. In addition, cell imaging studies of human liver cells (L-02) and rat neuronal cells (PC 12) hepatocytes show that sensor A can be used as a fluorescent probe for detecting Fe3+ in living cells. In a MeOH/HaO (2:3, v/v, pH 5.95) solution RBAP exhibits a high selectivity and excellent sensitivity for Sn2+ ions in the presence of many other metal cations. The binding analysis using the Job’s plot suggested the RBAP formed a 1:1 complex with Sn2+, and the binding association constant for Sn2+, Ka, was estimated to be 2.65 × 104M-1. The detection limit of Sn2+ by RBAP was determined to be 0.044 μM.The second chapter of this dissertation is about the design, synthesis and characterization of a novel fluorescent [2] rotaxane based on rhodamine B, which was composed of a dibenzyl-24-crown-8 (DB24C8) rings as a wheel, a rhodamine B and a 2,2-Diphenylacetyl chloride as the topper units. we efficiently synthesized the novel [2] rotaxane by esterification of alcohol with chloride without the help of catalyst, and this capping method is fast response, mild reaction conditions, easy separation, which perhaps will be a wide range of applications in the future.