A Distinguishing Recognition Type Fluorescence Sensor Based On A Biguanide Modified Phthalimide Derivative

Fluorescent sensors have been widely applied to food analysis,environmental monitoring and other fields due to they have advantages like good selectivity,high sensitivity,real-time online detection,and rich output signal,etc.Sensor arrays composed of a number of fluorescent sensors can generate a recognition fingerprint for a specific analyte by combing the fluorescent response signals of all the sensing units and realize discrimination of chemically or structurally similar analytes.However,there are some serious issues in using sensor arrays,for example,high dependence on a large number of sensing units,large sample consumption,complex data collection,etc.Therefore,it is important and challenging to develop a single fluorescent sensor with discrimination ability.Proteins are the fundamental components of living organisms and play vital roles in many processes of life.The identification of various proteins is of great significance.However,reports on single fluorescent sensor that can effectively differentiate proteins are limited.Therefore,in this dissertation,perylene and pyrene with multi emission signals were used as reporter groups to design a bispyrene-modified perylene derivative,which could empower the probe with cross-reactive multiple wavelength responses,so as to achieve discrimination of a variety of analytes.Thus,a bispyrene-modified perylene derivative was specially synthesized,and its discriminating properties were studied.The present dissertation covers the following two parts that have been conducted.In the first part,a bispyrene-modified perylene derivative,PEPBI,was synthesized and characterized.It is found that this molecule has multiple emission bands composing of both the emission peaks of pyrene and perylene units,and the cationic surfactant CTAB assemblies can effectively modulate the emission spectra of the probe in aqueous solution.The binary sensing system based on PEPBI and CTAB aggregates could be used to distinguish proteins.Protein titration experiments found that the sensing system exhibited a different response mode to non-metalloproteins and metalloproteins(a ratiometric response to non-metalloproteins and turn-off response to metalloproteins),and the fluorescence changes at different emission wavelengths was also different to a protein.Combing the data of emission variation of both pyrene and perylene units can form specific fingerprints for non-metalloproteins and metalloproteins,respectively.Linear discriminant analysis shows that this sensing system can distinguish among various proteins,not only achieve the distinction between different types of proteins,but also realize differentiation of proteins belonging to the same type.In the second part,the photophysical properties of PEPBI in different solvents and the identification of different solvents were investigated.Three kinds of organic solvent systems with similar structures were selected to be examined,which were methyl chloride with different chlorine atoms,organic alcohols with different alkyl chain lengths,and butanol with isomeric structures.It is found that the fluorescent probe has a certain ability to distinguish organic liquids with similar structures by exhibiting different color of the solvent.This is mainly due to the fact that the probe experiences different microenvironment in different solvents and has different distribution in the DMSO phase and other solvent phase,which may lead to different aggregation states,resulting in different luminescence in different solutions.And how to achieve data analysis and differentiation of similar solvents needs further studies.