Synthesis And Fluorescence Sensing Properties Of 2-Mercaptoimidazole Phenazine Derivatives

Recently,fluorescence sensing technology has emerged as an crucial instrument for targeted detection of analytes in the environment and in vivo owing to its advantages of simplicity,sensitivity,real-time detection and low cost.However,it is still challenging to construct an efficient and stable fluorescent sensing platform.Currently,fluorescence sensing platforms based on organic small molecules have attracted much attention.Among them,phenazine is one of the most attractive fluorescent molecules.Compared with other nitrogenous heterocyclic compounds,phenazine’s natural organic skeleton structure has the characteristics of large conjugated system and flexible modification,and it has become irreplaceable because of its excellent optical properties and biocompatibility.Therefore,the skeleton has been found widespread application in fluorescence sensing technologies.Based on this concept,we started from the synthesis of phenazine,summarized several synthetic methods of phenazine derivatives and the application of fluorescence sensing.Moreover,combined with the present research status of phenazine derivatives,a series of fluorescent molecules with imidazophenazine was designed and synthesized as the core.On this premise,the fluorescence sensing platform was constructed and studied the application of this platform in sensitive identification and detection of hazardous ions,volatile organic pollutants and isomers.This paper primarily consists of four sections:In the first part,various synthetic strategies of phenazine derivatives and their applications were summarized in fluorescent sensing through reviewing literatures,such as the identification and detection of hazardous ions,organic pollutants,biomolecules,volatile poisonous gases and other stimulatory response materials.In the second part,a dual-functional fluorescence sensor PZ was designed and synthesized.The sensor could quickly and sensitively detect poisonous Hg²⁺and CN^-in different systems.The detection methods were colorimetric and fluorescence dual-channel response.Compared with other interfering ions,PZ had high sensitivity and specificity to Hg²⁺and CN^-,and their detection time could be completed in tens of seconds.Additionally,the lowest detection limits of Hg²⁺and CN^-by PZ were 1.52×10^-8 M and 7.05×10^-7 M,respectively,which were far lower than WHO permissible drinking water limits.It is worth mentioning that PZ has also been successfully employed for the trace detection of Hg²⁺or CN^-in a variety of practical samples such as cosmetics,water samples and food.In the third part,a multiphase sensing platform PT based on diester-substituted-2-mercaptoimidazole phenazine was designed and developed.The platform could selectively detect volatile organic pollutant ethylenediamine（EDA）through fluorescence,naked-eye color and state changes.Meanwhile,PT could be used as a solid-state fluorescence sensor,which could not only achieve the naked-eye detection of EDA vapor,but also showed excellent stability.Studies indicated that the diesteryl functional groups on PT structure occurred"nucleophile substitution"with EDA to form the product with different fluorescence emission,resulting in obvious fluorescence changes after the interaction of PT and EDA.This reactivity detection strategy could efficiently distinguish between other aliphatic amines,and provided a simple and stable platform for EDA detection.Furthermore,the portable test box was prepared,which could be successfully used for the multiphase sensing and qualitative analysis of EDA.In the fourth part,a 2-mercaptoimidazolephenazine cyclodiamide PNH was designed and synthesized.The molecule’s solid material（PNH）effectively absorbed iodine vapor from the air.On this basis,iodine molecule（I₂）was introduced to regulate the stimulus response properties of PNH.Thus,a novel fluorescence sensing platform PNH-I₂ based on 2-mercaptoimidazolephenazine cyclodiamide was developed.The sensor platform enabled naked-eye identification and ultra-sensitive detection of o-phenylenediamine（OPD）,m-phenylenediamine（MPD）and p-phenylenediamine（PPD）at low concentrations.It was worth noting that the test box based on PNH-I₂could also be used as an intelligent fluorescent display material,which had good application value in the detection and identification of three phenylenediamine isomers.This work not only provides a simple and rapid strategy for the detection of phenylenediamine isomers,but also broadens the application field of phenazine derivatives in the development of environmental science.