Design And Construction Of Indicator For Organic Radical Based On Rhodamine

Objective:A series of radical indicators based on Rhodamine B was designed as the fluorescent indicator to understand the radical process of organic reactions.Method:A series of different substituted Rhodamine B amides derivatives（1-22）was synthesized by condensation reaction.The structure of these products is characterized by¹HNMR,¹³CNMR、HR-MS.It was found that amide derivatives of rhodamine B could be used in the visualization of free radical intermediates formed by thermal cleavage of different free radical initiators by naked eyes.At the same time,the optical properties and the recognition ability of these chromogenic substances were evaluated by the UV-Vis spectrophotometer and fluorescence spectrophotometer.In order to confirmed the recognition ability of these derivatives to free radicals in different chemical environments,color development and fluorescence analysis were investigated in different solvents.Finally,the proposed mechanism for the reaction of free radical and indicators were analyzed by HPLC-MS,GC-MS and IR.Results:The obtained target molecules were confirmed by modern analytical methods such as NMR and HR-MS.Through visualization by naked eyes,solvent adaptability investigation and fluorescence analysis were studied,it was found that（1）through screening,free radicals can be visualized by the obtained Rhodamine B arylamide derivatives;（2）through fluorescence analysis of the emission wavelengths of these derivatives between 580-600 nm,it can realize fluorescence visibility and partly visible to the naked eye;（3）It can realize visualization of the free radical by fluorescence in different solvents and colored reactions.Conclusion:A series of Rhodamine B amide derivatives that can detect free radicals were obtained,which will provide a simple and sensitive method for indicating free radical processes in organic reactions.