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Abstract A Donor-acceptor (D-π-A) type near-infrared fluorescent compound 2,3-is(4′-diphenylamino)−1,1′-biphenyl] −4-l) fumaronitrile (TPATCN) is fully characterized in a mono-disperse system as well as in film. Transient absorption (TA) data showed that intramolecular charge transfer (ICT) processes exist in the mono-disperse TPATCN molecule, and the corresponding transfer velocity is accelerated by solvent polarity. The energy transfers from the excited TPATCN to the surrounding polar solvent molecules via solvent cage effects based on dipole-dipole interactions. The TA data also showed that the exciton relaxation process involves the exciton-exciton annihilation (EEA) in the TPATCN film. The EEA replaces the ICT process for the mono-disperse system in the TPATCN film. The distance between single exciton and the EEA among excitons after exciton generation are estimated to be 7.8 Å and 356.8 Å, respectively. The former is much smaller than the size of a single TPATCN (28.3 Å) indicating that the intermolecular exciton is formed after photo-excitation in the TPATCN film. The latter is about 46 times that of a singel exciton, suggesting that the nature of EEA depends on the long-range interaction based on an electric filed. Moreover, the EEA process depends not only the distance among exciton after exciton generation but also the percentage of exciton participating in the EEA process in the whole exciton population. [ABSTRACT FROM AUTHOR]

Three push-pull chromophores comprising a triphenylamine (TPA) as electron-donating moiety and functionalized β-diketones as electron acceptor units are studied by various spectroscopic techniques. The time-correlated single-photon counting data shows that increasing the number of electron acceptor units accelerates photoluminescence relaxation rate of compounds. Transient spectra data shows that intramolecular charge transfer (ICT) takes place from TPA units to β-diketones units after photo-excitation. Increasing the number of electron acceptor units would prolong the generation process of ICT state, and accelerate the excited molecule reorganization process and the relaxation process of ICT state. [ABSTRACT FROM AUTHOR]

The key problem which needs to be solved during the commercialization process of the organic light emitting diode (OLED) lighting technology is how to improve the efficiency and stability of optoelectronic materials. In order to solute this issue, we explore the regulation of Ag nanoparticles (NPs) on the photoluminescence (PL) characteristics of an efficient organic optoelectronic polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene-vinylene] (MEH-PPV). Because of the coupling between the localized surface plasmons from the Ag NPs and the PL emission of the MEH-PPV, the Ag NPs could effectively enhance the PL intensity, modulate the spectral line shape and shorten the lifetime of interchain species. The temperature-dependent PL measurement exhibits that with the introduction of Ag NPs, the thermal exchange process between the sample and the surrounding environment becomes more effective, and the activation energy decreases from 448 to 318 meV. The excitation intensity (EI)-dependent PL measurement demonstrates that the thermal accumulation effect and the nonlinearity of EI-dependent PL enhancement are both suppressed by the Ag NPs. The results of this study will provide experimental guidance to the design and fabrication of OLED devices with high efficiency and stability. [ABSTRACT FROM AUTHOR]

Through comparing the linear and nonlinear optical property of two pull-push chromophores, which are composed of difluoroboron β-diketonate functionalized with carbazole and tert-butyl carbazole, the role of tert-butyl in chromosphere has been discussed in detail. The tert-butyl unit would lead to the absorption and fluorescence peak red shift and accelerate the fluorescence relaxation rate of chromophores. Moreover, the tert-butyl unit would affect obviously the two-photon optical property of chromophore according to the Z-scan test. The transient absorption (TA) data shows that these two pull-push chromopphores both own intramolecular charge transfer (ICT) characteristics and the tert-butyl unit accelerate the dynamic rate of ICT generation and relaxation process, which may be responsible for the variance of fluorescence property. [ABSTRACT FROM AUTHOR]

Two push-pull compounds, which are comprised of triphenylamine (TPA) (electron donor units) and functionalized β-diketones difluorboron complexes (electron acceptor units) are probed by many spectroscopies, which offers the relationship between electron acceptor and the intrinsic excited state properties of push–pull chromophores. We found that the photoluminescence (PL) intensity would enhance with the number of electron acceptor. Transient absorption (TA) data shows that intramolecular charge transfer (ICT) process really exists in the two molecules after photoexcitation and this process would be prolonged through increasing the electron-acceptor, which would be responsible for the improvement of PL property. [ABSTRACT FROM AUTHOR]

The photoluminescence (PL) characteristics of CdTe/ZnS quantum dots (QDs) infiltrated in TiO 2 inverse opal photonic crystals (PCs) are studied in detail. The PL dynamics of QDs show that the PCs could accelerate the PL relaxation rate of QDs as the PL peak of QDs is overlapped with the photonic stop band of PCs. Besides, the PCs could decrease the activation energy of QDs due to its porous structure and suppress the exciton annihilation process of QDs at high excitation intensity, owing to the light scattering effect. The final results are beneficial for people in further understanding the role of inverse opal PCs on manipulating the PL characteristics of QDs. [ABSTRACT FROM AUTHOR]

Paclitaxel, a microtubule-stabilizing chemotherapy drug, can cause severe paclitaxel-induced peripheral neuropathic pain (PIPNP). The roles of transient receptor potential (TRP) ion channel vanilloid 1 (TRPV1, a nociceptor and heat sensor) and melastatin 8 (TRPM8, a cold sensor) in PIPNP remain controversial. In this study, Western blotting, immunofluorescence staining, and calcium imaging revealed that the expression and functional activity of TRPV1 were upregulated in rat dorsal root ganglion (DRG) neurons in PIPNP. Behavioral assessments using the von Frey and brush tests demonstrated that mechanical hyperalgesia in PIPNP was significantly inhibited by intraperitoneal or intrathecal administration of the TRPV1 antagonist capsazepine, indicating that TRPV1 played a key role in PIPNP. Conversely, the expression of TRPM8 protein decreased and its channel activity was reduced in DRG neurons. Furthermore, activation of TRPM8 via topical application of menthol or intrathecal injection of WS-12 attenuated the mechanical pain. Mechanistically, the TRPV1 activity triggered by capsaicin (a TRPV1 agonist) was reduced after menthol application in cultured DRG neurons, especially in the paclitaxel-treated group. These findings showed that upregulation of TRPV1 and inhibition of TRPM8 are involved in the generation of PIPNP, and they suggested that inhibition of TRPV1 function in DRG neurons via activation of TRPM8 might underlie the analgesic effects of menthol. [ABSTRACT FROM AUTHOR]