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This paper presents a variety of conjugated derivatives with different number of arms (4-styryl-triphenylamine: C1, 4, 4′-di-styryltriphenylamine: C2, 4, 4′, 4″-tri-styryltriphenylamine: C3). The linear absorption and fluorescence maxima and the molar extinction coefficients are in the order of C1< C2< C3 in various solvents. Two-photon absorption (TPA) up-converted emission of the derivatives were determined with Ti:sapphire femtosecond laser. The maximal TPA emission wavelength and the two-photon absorption cross section of the derivatives are also in the order of C1< C2< C3 in various solvents. The dipole moment changes of the derivatives between the excited state and the ground state were estimated from experiment, and they are in the order of C1< C2< C3, which is confirmed further by the molecular geometry optimization of the derivatives. The electron density distribution and the energy levels of the frontier orbital of the derivatives were analyzed. The cyclic voltammograms of the derivatives were performed and discussed. [ABSTRACT FROM AUTHOR]

This paper presents a range of novel new branched conjugated dyes containing benzophenone moiety. As compared with those of 4-( p-benzoyl-styrene)yl-4′-(styrene)yl-triphenylamine ( C1) and 4-( p-benzoyl-styrene)yl-4′-3,4,5-trimethoxyl-styrene)yl-triphenylamine ( C2), the maximal linear absorption and emission wavelength of 4-( p-benzoyl-styrene)yl-4′-( p′-nitro-styrene)yl-triphenylamine ( C3) displays red-shifted remarkably, While the fluorescence quantum yields of C3 are lower than those of C1 and C2 in various solvents. The fluorescence lifetimes of the derivatives were measured, and radiative and non-radiative transition constants of the derivatives were calculated. Two-photon absorption (TPA) optical data of the derivatives were measured by Ti:sapphire femtosecond laser tuning from 720 to 880 nm at intervals of 20 nm. TPA induced fluorescence emission of C3 is red-shifted with respected to that of C1 and C2. TPA cross sections of C3 are larger than those of C1 and C2 in various excited laser frequencies. TPA cross section of C2 and C3 are much larger than those of 3,4,5-(trimethoxylstyrene)yl-triphenylamine ( C4) and 4-( p-nitrostyrene)yl-triphenylamine ( C5) respectively under various near-IR Ti:sapphire femtosecond laser wavelength. C1 and C2 show similar one- and two- photon optical nature. Geometry optimization with ab initio method confirms that C3 has different electron density distribution, the energy levels in frontier orbitals, the dipole moment changes, the absorption and emission spectroscopy from those of C1 and C2. The cyclic voltammograms of the derivatives were detected in methylene chloride at various scan rates, and the energy of frontier orbials were estimated further from the redox potentials. [ABSTRACT FROM AUTHOR]

Suitable chemical strategy is a useful approach on the tuning color and photoluminescence of organic dyes. This paper presented tuning novel branched p-nitro-stilbene derivatives efficiently with a new chemical strategy through variation of chemical bridged bond. Linking bonds played significant effects on the absorption and fluorescence spectroscopy of the branched p-nitro-stilbene derivatives. A change from "D-π-A" to "A-π-A" chemical structural characteristics occurred for the branched p-nitro-stilbene derivatives as ester bond was attached. This led to not only large hypsochromic shift of the maximal absorption wavelength of the branched p-nitro-stilbene derivatives, but considerable reduction of the fluorescence intensity. While in contrast, the branched p-nitro-stilbene derivatives with ether bond exhibited longer wavelength absorption and much stronger fluorescence emission in modest polar solvent. The cyclic voltammograms of these branched p-nitro-stilbene derivatives were determined. Different electrochemistry processes were observed for the branched p-nitro-stilbene derivatives with various linking bonds. The energies of frontier orbital of the branched p-nitro-stilbene derivatives were estimated from their corresponding redox potentials. Molecular geometry optimization of the branched p-nitro-stilbene derivatives was performed, and the electron density distribution of frontier orbital was analyzed. Thermal stabilities of these branched nitrostilbene derivatives were investigated via the analysis of the differential scanning calorimetry (DSC) and thermograving (TGA) curves. This paper presented strong evidences that the absorption and fluorescence spectroscopy of the branched stilbene derivatives could be mediated efficiently by chemical strategy. [ABSTRACT FROM AUTHOR]

Abstract  Novel nitro-azobenzene dyes bearing one or two benzophenone branches were proposed and synthesized to improve their photophysical and photochemical properties. The new dyes exhibited double UV/visible bands, and they displayed weak fluorescence emission as excited at 350 nm. Single crystal X-ray diffraction data showed that two phenyl rings of azobenzene was almost coplanar, and the benzophenone part was neither coplanar nor linear connection with azobenzene via ether bridged bond, which have good fit with molecular geometry optimization calculation results. The cyclic voltammeric results of nitro-azobenzene dyes were firstly reported in this paper, which demonstrated that the electrochemical properties of nitro-azobenzene dyes was altered by the substitution of benzophenone part. Thermal stabilities of the new dyes were studied by the analysis of differential scanning calorimetry (DSC) and thermograving (TG) in this paper. Efficient visible-light photoinitiating polymerization of methyl methacrylate (MMA) by the novel nitro-azobenzene dyes was presented and discussed. [ABSTRACT FROM AUTHOR]

Abstract  In this paper, 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 NMR and element analysis. The single crystals of two target compounds (11 and 12) have been obtained, and their X-ray crystallographic data have been determined and discussed. Remarkably different absorption and fluorescence spectroscopy was observed for nitro-stilbene derivatives with benzophenones via different linked bonds. The results show that electron-donating or electron withdrawing bridged bonds have significant influence on the absorption and fluorescence spectroscopy, which makes it possible for the development of ideal nitro-stilbene dyes with benzophenones through chemical strategy. [ABSTRACT FROM AUTHOR]