Theoretical Study On Recognition Mechanism And Coordination Mode Effect Of Two Photon Zinc Ion Probe

Since the emergence of laser,the theoretical research on nonlinear optics has developed rapidly,and its related materials have shown good applications in many fields,such as integrated optics,quantum optics and so on.Two-photon absorption is an important third-order nonlinear optical effect.Its organic materials are widely used in two-photon fluorescence microscopy due to their good designability and tailorability.Two photon fluorescence microscope combines two-photon excitation technology and laser scanning technology,which can observe the two-photon fluorescence probes in living cells,and is widely used in cell detection and microbial observation.In this paper,the one-photon absorption,fluorescence emission and two-photon absorption properties of a series of two-photon zinc ion fluorescent probes are calculated by using time-dependent density functional theory and response theory.The molecular structure changes in solvent are simulated by molecular dynamics simulation.The main contents and conclusions are as follows:1.Response mechanism and coordination mode effect of bipyridine based two-photon zinc ion fluorescent probeUsing the time-dependent density functional theory,the one-photon absorption,emission and two-photon absorption properties of a two-photon zinc ion probe based on bipyridine group are studied.The dihedral angle between two pyridine rings in solvent is investigated by molecular dynamics simulation.It is found that the intramolecular charge transfer ability is enhanced after coordination with zinc ion,which leads to the red shift of two-photon absorption wavelength and the increase of two-photon absorption intensity.The fluctuation of dihedral angle between two pyridine rings leads to the blue shift of two-photon absorption wavelength and the decrease of two-photon absorption cross section.Coordination modes have great influence on the two-photon absorption properties.The two-photon absorption wavelength of the compound composed of Zn²⁺and two ligands is more in line with the experimental results.2.Isomerism and coordination mode effects of two-photon zinc ion fluorescent probe based on tris(pyridylmethyl)amine groupThe one-and two-photon absorption properties of a two-photon zinc ion probe based on the recognition group of tris(pyridylmethyl)amine are calculated.According to the probe molecule synthesized by the experimenter,the optical properties of the structure with stronger electron withdrawing group are considered.The results show that the isomerism effect is very important for the two-photon absorption properties.Different coordination modes give rise to different charge transfer ability.When zinc ion is combined with the pyridine group in the middle of the molecule,the complex has a strong two-photon absorption in the longer wavelength range.3.The influence of hydrogen bond in the two-photon absorption properties of green fluorescent proteinThe hydrogen bonding structures of a push-pull molecule derived from green fluorescent protein(GFP)in aqueous solution is simulated by molecular dynamics simulation.Employing the density functional theory,the one and two-photon absorption properties of various hydrogen bonding structures are calculated.It is found that the influence of the type,position and number of hydrogen bonds in the two-photon absorption properties can not be ignored.As the number of hydrogen bonds increases,the two-photon absorption cross section increases.The two-photon absorption properties of N…H and O…H structures are also different.There are six chapters in this paper:the first chapter is the introduction,which briefly introduces the nonlinear optics and two-photon metal fluorescent probes and their related theoretical research.The second chapter introduces the theoretical calculation methods of optical properties,including the calculation methods of one and two-photon absorption properties.In the third chapter,we study a kind of two-photon zinc ion fluorescence probe containing bipyridine group,focusing on the recognition mechanism of the probe and the coordination mode effect on the two-photon absorption properties.In forth chapter,the effects of isomerism and coordination mode on the one-and two-photon absorption properties of a zinc ion fluorescent probe based on tris(pyridylmethyl)amine group are studied.In Chapter five,we study the effect of hydrogen bonding on the two-photon absorption properties of a green fluorescent protein molecules.The sixth chapter summarizes and prospects the work of this paper.