الفهرس 
Introduction and Literature SurveyOnly 14 pages are availabe for public view
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Abstract
Despite the compound 1-((E)-2- phenylethenyl) -2-(4-(2-((E)-2-phenylethenyl) phenoxy) butoxy) benzene (PPPBB) having a Chemical Abstracts Service (CAS) Registry Number 864867-98-1 and a CAS Index Name, there are no data available in literature. The present study is concerned with the characterization of this compound by studying its UV-visible absorption and fluorescence spectra, the influence of solvent polarity on photophysical and photochemical reactivity, X- ray single crystal structure, Density functional theory TD-DFT studies and its interaction with DNA acting as a DNA Stain in the important UV- regionthat gains interest in confocal fluorescence microscopy. This thesis comprises three chapters as follow: Chapter (1) : Introduction. This chapter includes a general introduction about photophysical processes of excited states, effect of solvent on electronic absorption and emission spectra and excited state lifetime as well as literature survey on stlibene deraivatives and its applications. Chapter (2) : Experimental The second chapter include the experimental part. It describes all the chemicals and solvents used in the measurements and all apparatus used like UV-visible spectrophotometer, spectrofluorometer, excited state lifetime apparatus, Single crystal X-ray analysis. This chapter includes also methods of the measurements the fluorescence and photochemical quantum yields light intensity calculation, lifetimes and rate constant calculations Chapter (3): Results and Discussion. The third chapter include results and discussion of theoretical and practical results including X- ray single crystal structure, thermal stability, electronic absorption and emission spectra, lifetime measurement, fluorescence quantum yield , molecular orbital calculations using TD-DFT and geometrical optimization to a minimum energy with B3LYP of the density functional theory (DFT) with basis set 6–31 G(d). The electronic UV-Vis. spectra of PPPBB in different solvents were stimulated by using TD-DFT with the 6-31G(d) basis set. The molecular electrostatic potential maps (MEP) for PPPBB molecular structures in both the E- and Z-forms in the ground and excited states were obtained. In the E-configuration, the negative potential site in the ground state is shown at the center of phenyl and vinyl groups, while it is little bit shifted in the excited state. The positive potential regions are localized over the center of the molecule and the hydrogen atoms. For the Z-configuration, the negative potential site of PPPBB in ground state is around O atoms, while the negative potential sites in excited state are shifted to the center of phenyl and vinyl groups. The positive potential regions are around the hydrogen atoms. PPPBB shows little solvent polarity on both electronic absorption and emission spectra reflecting low polarity effect in both ground and excited states. Some molecular parameters including excited state lifetime, oscillator strength and dipole moment have been calculated. The oscillator strengths and transition dipole moments indicate that the So→S1 transition is an allowed transition of π→π* character. The photostability of PPPBB in different solvents upon UV irradiation (λ = 310 nm) was studied and the rate constants of photodegradation together with the photochemical quantum yields (c) were calculated in different solvents by applying the slope method according to the first order rate equation. The interaction of PPPBB with (DNA) was studied by flourescence spectroscopy and the binding constant was calculated. PPPBB was sumitted as a patent under the name Tanta DNA Stain 4. Its selective fluorescence binding to DNA has been identified with a significant increase in fluorescence intensity upon binding, making this dye an alternative to unhealthy commercial dyes such as ethidium bromide. The increase was detected up to twenty-five times upon selective binding to DNA. The advantage of PPPBB is that the wavelengths used in fluorescence excitation (280 nm) or for the amplified fluorescence when bound with nucleic acids (380 nm) are among the shortest values of the wavelengths recorded in this field. This low-value wavelength has a major role in improving resolution in microscopy used to examine proteins, cells and living tissues. In an ideal optical system, the resolution of separation is restricted by a few optical components, including the wavelength of light, whether used in excitation or emission.