Synthesis And Properties Of Rhodamine-Based Fluorescence Sensor Based On FRET Mechanism

In recent years,due to the excellent photophysical and photochemical properties of rhodamine-based derivatives,the properties of the rhodamine derivative spironolactone ring have been converted into an open-loop structure after interaction with the target analyte.At this time,it changes from a non-fluorescent state to a strong fluorescence emission,and the color change is obvious,and is often used as a colorimetric fluorescence sensor.The fluorescence sensor can be used not only for the detection of cations,but also for the sensing and identification of pH,anions and biologically active substances.Based on the mechanism of fluorescence resonance energy transfer?FRET?,three kinds of rhodamine-based derivative multi-response fluorescence sensors?naphthalimide-rhodamine derivative,coumarin-rhodamine derivative,and diarylethene-rhodamine derivative?were designed and synthesized.The properties were studied by UV and fluorescence spectroscopy.The main research contents are as follows:The first chapter introduces the research background and detection mechanism of fluorescence sensor,and the research situation of rhodamine derivatives.Through the research and analysis of the system,the research content of this subject is put forward.In the second chapter,a two-channel fluorescence sensor 1A with large emission wavelength shift was designed by linking the naphthalimide and rhodamine fluorophores with piperazine,which can be used for sequential detection of Cu²⁺and H₂S,as a multi-response fluorescence sensor.Among the many cations,the sensor specifically recognizes Cu²⁺,and two spectroscopy-enhanced fluorescence emission peaks appear at 528 nm and 610 nm,and the color changes from colorless to pink.Then,only after the addition of H₂S,the fluorescence was quenched and the color returned to the original solution state.In addition,it is preliminarily proved that the sensor is permeable to cell membranes and can be used in cell imaging applications to achieve dual-channel fluorescence emission in HeLa living cells.In the third chapter,the coumarin and rhodamine B fluorophores were designed by piperazine to synthesize a colorimetric and ratiometric fluorescence sensor,which can be used for sequential detection of Cu²⁺and Arg,and can be used as a multi-response fluorescence sensor.In the UV and fluorescence spectra,sensor 1B has higher selectivity to Cu²⁺than other competitive metal ions and has good anti-interference ability.In the process of detecting Cu²⁺,not only the ratio-type fluorescence change with large emission offset?125 nm?is realized,but also the color change of the solution is obvious,which can be recognized by the naked eye.The complex of sensor 1B with Cu²⁺can be successfully applied to the detection of Arg with high selectivity.The color change of the solution apparently changed from pink to pale yellow,and fluorescence quenching was achieved.In addition,the feasibility of sensor 1B in intracellular Cu²⁺ratio imaging has been initially studied using HeLa cells.In the fourth chapter,a multi-response fluorescent chemical sensor was designed and synthesized.The diarylethene group was linked to the rhodamine fluorophore by intramolecular piperazine,and the highly reactive spirolactam group of rhodamine as a reaction site,which helps to promote the introduction of other coordinating groups.Sensor 1C uniquely identifies Hg²⁺,exhibiting a significant"naked eye"color change and a selective fluorescent"off-on"response,which can be used for Hg²⁺detected colorimetric and fluorescence enhanced sensors.The fluorescence of the sensor with Hg²⁺complex(1C-Hg²⁺)can be easily adjusted by the FRET mechanism under the alternating irradiation of ultraviolet light and visible light,has good photochromism and fluorescent switching performance,and exhibits excellent fatigue resistance and photobleaching resistance.