Study On The Excited-state Dynamics Behavior And Photophysical Properties Of Some Special Kinds Of Intramolecular Proton Transfer

Kinds of new intra-molecular proton transfer systems were investigated in both ground and excited states.The stable configurations were obtained through Density Function Theory(DFT)and Time-dependent Density Function Theory(TD-DFT).Combined with the hydrogen bond changes in different excited states,we used the IR spectra of special functional groups,Front Molecule Orbital,absorption spectra,emission spectra and etc to investigate the spectra shift,electron redistribution and intra-molecular proton transfer.In the first chapter,the photo-excitation and decay processes,the property and influence of hydrogen bond were briefly introduced,and then present the main research contents of the paper.In the second chapter,some main quantum mechanics methods to study the electronic structures of multi-electron systems were introduced,and the Density Function Theory(DFT)and Time-dependent Density Function Theory(TD-DFT)were mainly introduced.The third chapter focus on properties of the ground and excited states indigo and its derivative molecules.The results demonstrate that the intramolecular hydrogen bond I is weakened and the intramolecular hydrogen bond II is strengthened upon photo-excitation to the S1 state.In the absorption spectra,the substitution at R4R4,of indigo causes a significant redshift.In addition,the halogen substitution obviously increases the electron transfer mobility of indigo.It is proved that the halogen substitution may be a new method to design high performance organic semiconductors.The forth chapter introduce excited-state double proton transfer process(ESDPT)of the1,3-bis(2-pyridylimino)-4,7-dihydroxyisoindole(BPD).The hydrogen bond strengthening promotes the proton transfer in the S1 state effectively.The potential energy surface can investigate the proton transfer process directly.The fifth chapter focus on the influence of ?-conjugation framework in1,8-Dihydroxydibenzo[a,c]phenazine(DHBP)on the excited-state proton transfer.The increment of?-conjugation framework effectively decreases the Stokes shift and promotes the proton transfer.The potential energy surfaces of DHBP indicate that the reverse double-proton transfer can spontaneously happen in ground state.The sixth chapter mainly focus on the newly synthesized blue fluorescence protein(BFP)molecule combined with its anchoring group substitution derivatives.The substitution of malonic and malononitrile groups can create the fluorescence quenching phenomenon,which may be caused bytheir participation in the excited state charge redistribution and act as important electron-donating groups.