Spectroscopic Properties And Energy Transfer Of Aminobenzothiazole And Its Porphyrin / Zinc Porphyrin Bridged Compounds

In this paper,2-(2-aminophenyl)benzothiazole(APBT)and its 2-(2,5-diaminophenyl)benzothiazole(DABT)derivatives,tetraphenylporphyrin(TPP)and tetraphenylzinc porphyrin(Zn TPP),and two kinds of binary luminescent compounds,APBT-TPP and APBT-Zn TPP,were synthesized.The effects of solvent effect and substituent effect on the electronic spectra and excited state intramolecular proton transfer(ESIPT)of DABT were investigated.The fluorescence resonance energy transfer(FRET)between APBT and TPP,APBT and Zn TPP was studied.The influence of solvent effect on the spectral properties of binary luminescent compounds was analyzed.1.The fluorescent compound DABT was synthesized,the electronic spectra of DABT in different solvents were measured,and the electronic spectra and possible ESIPT process of DABT were analyzed by the quantitative calculation of TD DFT B3LYP/6-311++G(d).Both experimental and calculated results show that the maximum absorption and emission wavelengths of DABT are red shifted with the increase of solvent polarity.It is also found that the fluorescence emission intensity increases with the increase of solvent polarity in aprotic solvent,while in proton solvent,DABT-H⁺is formed due to protonation of solvent,which makes the fluorescence partially quenched,and the fluorescence emission intensity of DABT decreases with the increase of solvent polarity.2.A series of amino hydrogen substituted derivatives at 5-position of DABT were synthesized,the electronic effect of substituents on the absorption and emission spectra of DABT was examined by using tetrahydrofuran as solvent,It was found that the electronegativity of the substituents could significantly affect the electronic spectral properties.A series of related theoretical data,such as frontier orbital energy level difference,electronic spectrum data and plane structure parameters,are obtained by time-dependent density functional calculation,and the experimental conclusions are demonstrated and expounded.3.APBT,TPP and Zn TPP were synthesized and their interactions were studied.According to the electronic spectrum test,it can be found that the emission spectrum of APBT and the absorption spectrum of TPP/Zn TPP overlap to a great extent.according to F?rster's fluorescence resonance energy transfer(FRET)theory,On this basis,a FRET system with APBT as energy donor and TPP/Zn TPP as energy acceptor can be established.Compared two FRET systems,APBT/TPP and APBT/Zn TPP,to investigate the effect of the receptor structural change on the energy conduction in the FRET system.4.Two binary luminescent compounds,APBT-TPP and APBT-Zn TPP,were synthesized.The electronic spectra of the two compounds in different solvents were measured.It was found that the fluorescence intensity of the two compounds increased with the increase of solvent polarity.According to the test results under different p H conditions,it is confirmed that the intramolecular energy transfer can take place in APBT-TPP and APBT-Zn TPP.At the same time,the quantitative calculation method of B3LYP/6-31G(d)is used to optimize the structure of APBT-TPP.Based on this,the molecular surface electrostatic potential diagram and frontier molecular orbital data are obtained.