Synthesis And Application Of Carbazole-Based Fluorescent Probe

Carbazole derivatives are a class of conjugate system of matter and often used to construct intramolecular charge transfer effect?ICT?.Also,they are often used as a kind of electron-donating group and show large Stokes shift.Synthesis of carbazole-based fluorescent probe is recently attracting a considerable interest owing to their simplicity,high sensitivity and inexpensive nature.In this work,we designed and synthesized three carbazole-based fluorescent probes for CN^-,HSO₃^-,ClO^-as well as p H detection.The main contents are as follows:Chapter 1: We describe the concept of molecular recognition and fluorescent probe,briefly.Then,we introduce the concept of carbazole-based fluorescent probe.And we present its research progress in detail.Chapter 2: We report a single water-soluble broadly emitting?500-650 nm?carbazole-based fluorescent probe?Probe 1?,which can respond to CN^-,HSO₃^-and extremely alkaline pH,via the ethylene bridging of 3-formyl-N-ethylcarbazole and 2,3-dimethyl benzothizolium iodide.Here,CN^-and HSO₃^-are expected to be undergone 1,4-addition reactions.In DMSO media,the ratiometric probe not only displays high sensitivity and selectivity toward CN^-ions,but also exhibits two well-separated emission peaks before and after the CN^-addition??? =199 nm?.The supernal selectivity and sensitivity of Probe 1 are also achieved toward HSO₃^-ions and alkaline pH in water.Importantly,Probe1 features remarkable large Stokes shift,good stability and rapid response for CN^-,HSO₃^-and extremely alkaline pH sensing.Fluorescent CN^-and HSO₃^-imaging in living cells by Probe 1 are also successfully applied.Last but not least,laser scanning confocal microscopy of Escherichia coli cells indicates that Probe 1 could image alkaline pH values fluctuations in biological systems.Chapter 3: We report a novel ratiometric carbazole-basedfluorescence probe?Probe 2?for monitoring cyanide ion via the ethylene bridging of N-ethylcarbazole-3-formaldehyde and1,1,2-trimethyl-3-ethyl-1H-benz[e]indolium iodide.Here,CN^-is expected to be detectable by nucleophilic attack toward the carbon atom of the C=N group.Two well-separated emission peaks before and after the CN^-addition could be obtained,as well as an obvious color change.Notably,this probe was found to show high selectivity and sensitivity for CN^-,and also importantly,it is able to detect CN^-at extremely low concentrations,quantitatively.Moreover,fluorescent CN^-imaging in living cells by this probe was also successfully applied.Chapter 4: We report a unique type of carbazole-based fluorescent probe?Probe 3?,which can monitor ClO^-with significant fluorescent turn-on responses.The reaction mechanism could be reasonably explained that ClO^-could oxidize the probe.The new fabricated probe this probe is found to show high selectivity and sensitivity for ClO^-.And also importantly,it also shows favorable optical properties for ClOdetection in living cells,which indicates that the probe could noninvasively image ClO^- in biological systems.