Synthesis And Characterization Of Various Excited-state Properties Of The Two Photon Photosensitizer

The photophysical and photochemical properties induced by two-photon absorption is different from those induced by one-photon absorption, which makes the two-photon absorption (TPA) materials had great potential applications in many fields. Recently, more and more attention has been paid to the organic dyes'large two-photon absorption (TPA) effects because of their various applications such as optical power limiting up-converted lasing, three-dimensional optical data storage, two-photon fluorescence excitation microscopy, photodynamic therapy and micro fabrication. In 1993, S.R.Marder and coworkers calculated nonlinear optical polarization of the conjugated molecules from the theory. In 1997, Marder and coworkers reported that bis(styryl)benzene derivatives with donor-Ï€-donor donor-acceptor-donor, and acceptor-donor-acceptor structural motifs exhibited exceptionally large two-photon effects. Almost at the same time, Prasad and coworkers designed and synthesized similar molecules, which made the research on the two-photon compounds entered a new stage. Some two-photon dyes with stilbene structures which have various excited-state properties have been designed and synthesized in this paper. Two main aspects of research were listed as followings:1. we have presented a range of new nitro-stilbene derivatives with benzophenones via ether or ester bridged bond. These nitro-stilbene derivatives with benzophenones have been conveniently obtained by condensation reaction. The linked benzophenones were efficiently introduced to nitro-stilbene dyes. The structures of these compounds have been characterized with 1H-NMR, 13C-NMR and element analysis. The single crystal of compound (C14) has been obtained, and its X-ray crystallographic data have been determined and discussed. The results of electrochemistry showed that the energy of the frontier orbital and electron density of compounds had some relationship with the position of the substituted benzophenone parts. The optical properties of these compounds were fully studied. The relationship between the structure and properties were also discussed. The solvent's effects on the UV absorption and fluorescence were studied. Remarkably different absorption and fluorescence spectroscopy were observed for nitro-stilbene derivatives with benzophenones via different linked bonds. The results showed that electron-donating or electron-withdrawing bridged bonds had significant influence on the absorption and fluorescence spectroscopy, which could be used for the development of the ideal nitro-stilbene dyes with benzophenones through chemical approaches.2. In order to explore the two-photon photodynamic therapy, we designed and synthesized three stilbene derivatives with multi-bromine substituents. The structure of these compounds were characterized by ¹H-NMR,¹³C-NMR and elemental analysis. The structure of compounds were furtherly confirmed by thermal analysis. The single crystal of compound (C19) was obtained, and the X-ray crystallographic data were determined and discussed. UV-Vis absorption spectrum showed that they had large absorption on visible area, while no fluorescence emission was observed. In the irradiation of UV-visible light, singlet oxygen could be generated by the compounds with detection by chemical approach.