Synthesis And Photophysical Behavior Of 2-(2-Hydroxyphenyl) Benzothiazole And Its Dyad With Porphyrins

2-?2-hydroxyphenyl?benzothiazole?HBT?and its derivatives are a kind of typical proton transfer organic molecules.Porphyrins are also a class of molecules with unique fluorescence properties.These compounds not only have large stokes displacement and high fluorescence quantum yield,the central framework of their fluorophore but also can be modifed to obtain derivatives with different fluorescence properties.In view of this,new functional materials with excellent properties of the two can be obtained by connecting them with appropriate bridging groups.Therefore,this paper adopts the method of combining theoretical calculation and experiment to study the solvent effect and the effect of the substituent effect on HBT proton transfer,and dyad?HTP?,was synthesized by fluorescence spectrometry and analyses the influence of different solvents HTP uv spectra and fluorescence emission spectrum,furthermore,form the 2-?2-hydroxy-5-amino phenyl?benzothiazole?HBT-NH2?and amino porphyrin?TPP-NH2?system of fluorescence resonance energy transfer?FRET?,the influence for receptor concentration in this system were analyzed.1.In this paper,2-?2-hydroxyphenyl?benzothiazole and its derivatives were synthesized by optimizing the traditional synthesis method.The effect of solvent effect and substituent effect on HBT proton transfer was studied by measuring ultraviolet spectrum and fluorescence spectrum.Experimental results show that HBT interacts with solvents in strongly polar solvents to form phenol-oxygen anions,and fluorescence peaks of phenol-oxygen anions can be observed near 460 nm.With the decrease of polarity,the fluorescence peak at 460 nm disappeared and a new fluorescence peak,namely keto fluorescence peak,appeared at the long wavelength.Therefore,the decrease of solvent polarity is beneficial to the proton transfer process.Fluorescence spectrometry showed that the hydroxyl pair of HBT was replaced by different groups and different positions were replaced by the same group,and double fluorescence emission peaks appeared,namely enol fluorescence peak and keto fluorescence peak.When the electron-donating group,such as the tert-butyl group,hinders the proton transfer process of HBT,In the case of electron-absorbing groups such as aldehyde group,the molecule is easy to achieve stable structure through ESIPT process.By analyzing the fluorescence spectra of HBT substituted at different positions,it was found that the change of the spectral properties of HBT was related not only to the adsorption or electron supply properties of the substituents,but also to the positions of the substituents.To further verify the accuracy of the experimental results,the bond length,charge density,ultraviolet and fluorescence spectra of HBT and its derivatives were calculated by density functional theory.The calculated results are in good agreement with the experimental results,which further illustrates the influence of substituents on HBT proton transfer.2.The ultraviolet and fluorescence spectra of HBT-NH₂ and TPP-NH₂ were determined,and it was found that the two can be used as the donor and recipient of FRET system respectively.The fluorescence emission spectra were determined by changing the donor concentration or the receptor concentration.The experimental results showed that when the donor concentration remained unchanged and the receptor concentration was changed,the donor fluorescence intensity decreased and the receptor fluorescence intensity increased with the increasing of the receptor concentration.On the contrary,when the donor concentration was changed while the receptor concentration remained unchanged,the fluorescence intensity of the receptor decreased with the increase of the donor concentration.It indicates that the change of donor and recipient concentration has a great impact on the FRET system composed of HBT-NH₂ and TPP-NH₂.3.The structure of HBT and TPP-NH₂ were modified by means of appropriate bridging groups to connect them.Binary compounds were synthesized and characterized by nuclear magnetic hydrogen spectra and mass spectra.Ultraviolet absorption spectra and fluorescence emission spectra of HTP in different solvents were determined.The experimental results showed that in different solvents,HTP had strong absorption peaks around 417nm and four weak absorption peaks within 450-650nm.In the fluorescence spectrum,it could be seen that with the increase of solvent polarity,the fluorescence peak of HTP near 650nm showed an increasing trend,indicating that HTP was greatly affected by solvents,but had little influence on its peak.