Novel Fluorescent Viscosity And ROS Probes Based On Tuning ICT Effect Of D-pai-A Fluorophores

Intramolecular Charge Transfer(ICT) mechanism is of great interest concerning theoretical investigation and applications in fluorophore/prone design.Detection of viscosity of microenvironment and reactive oxygen species(ROS) with fluorescent probes based on ICT mechanism are still in its very early infancy.The fluorescent molecular rotors sensitive to viscosity are in very limited number and the structure of the reported rotors is highly conserved to 9-(dicyanovinyl)-julolidine(DCVJ).The traditional DCVJ type of rotors suffer from short emission wavelength,small stokes' shifts,etc.Besides viscosity,solvent polarity can cause solvatochromic effect in molecular rotors,and their fluorescent intensity can be influenced by solvent viscosity.The constant x in the F(o|¨)rster-Hoffmann Equation can be interpreted as the rotor's sensitivity towards viscosity,but the relation between the molecular structure and the x values of the molecular rotors have not been systematically investigated.The fluorescent probes sensitive to ROS based on ICT are few,and most of the present ROS probes are fluorescence intensity based probes.Very few ratiometric fluorescent probes toward HOCl has been reported.Based on tuning the ICT effect of D-Ï€-A fluorophores,we envision that ratiometric fluorescent probes can be obtained for detection of ROS.In order to selectively sensing the microviscosity and ROS,and to investigate systematically the structure-x relation of the molecular that would occur ICT process,the following works were carded out in this thesis:A family of molecular rotors v-1 to v-10 with dicyanovinyl group,and extendedÏ€-conjugation system were synthesized.It is found both extending n-conjugation system and changing the electron-donating ability of the substitutions can make the fluorescent rotors more sensitive to solvent polarity.Wither or not a rotor shows the viscosity sensitivity depends on their polarity sensitivity.Extending n-conjugation system,changing the electron donor group or increasing the molecular size can improve the photophysical properties of rotors.The rotor V-9 is more sensitive to viscosity than all the reported rotors.The phenothiazine derivates R-1 to R-7 were synthesized,and these compounds were applied to detect H₂O₂ and HOCl.R-1 is a colorimetric and ratiometric fluorescent probe for H₂O₂ and HOCl,and it showed higher selectivity toward HOCl.Moreover,it was demonstrated that R-1 can be used for in vivo detection of HOCl in zebrafish treated (pretreated with HOCl).The change of R-3 from weak fluorescence to strong fluorescence after reacting H₂O₂ and HOCl can be used for detection of H₂O₂ and HOCl quantitatively and qualitatively,and it showed higher selectivity toward HOCl over other ROS.