Based on these findings, phosphorylation of p38 MAPK via P2X(7)R may induce tactile allodynia/hyperalgesia, which is most likely mediated by sTNF-α released by microglia.
Mechanofluorochromism is found for a series of benzofuro [2,3-c]oxazolo [4,5-a]carbazole-type fluorophores (1a-1d) having cyano groups as acceptor: grinding of 1a-1d induces a fluorescent color change with an enhanced quantum yield, and the fluorescent color is recovered by heating or exposure to solvent vapor. Interestingly, both absorption and emission peaks are redshifted by grinding, in conflict with the common view. On the basis of time-resolved fluorescence spectroscopy, X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), and single-crystal X-ray structural
As new-type donor-acceptor π-conjugated dyes capable of forming a strong interaction between the electron-acceptor moiety of the sensitizers and a TiO 2 surface, fluorescent dye OH11 and pyridinum dye OH12 with a pyridine and pyridinium ring as the electron-accepting group, respectively, have been designed and synthesized as photosensitizers for use in dye-sensitized solar cells (DSSCs). The fluorescent dye OH11 exhibits an absorption band at around 410 nm and a fluorescence band at around 530 nm. On the other hand, the pyridinum dye OH12 shows an absorption maximum at around 560 nm, assigned to a strong intramolecular charge-transfer excitation from the dibutylamino group to the pyridinium
Heteropolycyclic donor--acceptor (D--A) structural isomers of benzofuro[2,3-c]oxazolo[4,5-a]carbazole-type (2a-f) and benzofuro[2,3-c]oxazolo[5,4-a]carbazole-type fluorescent dyes (3a-f), which differ in the position of oxygen and nitrogen atoms of the oxazole ring, have been synthesized, and their photophysical and electrochemical properties have been investigated. The fluorescent dyes 2a-f exhibit much stronger intramolecular charge transfer (ICT) absorption and fluorescence bands than 3a-f. Both of the D-pi-A structural isomers showed bathochromic shifts of the fluorescence band and a decrease in the fluorescence quantum yields with increasing solvent polarity (i.e., positive fluorescence solvatochromism), and the bathochromic shifts for 3a-f were larger than those for 2a-f. The fluorescent dyes 2a-c and 3a-c, which have cyano and carboxyl groups, and carboxylic acid ester as electron-withdrawing substituents, exhibited significant fluorescence solvatochromic properties, compared to 2e, 2f, 3e and 3f without an electron-withdrawing substituent. The fluorescence solvatochromism of the fluorescent dyes were analyzed with the Lippert-Mataga correlation. Moreover, to elucidate the differences of photophysical properties among the fluorescent dyes, we have performed time-resolved fluorescence spectroscopic measurements, and a change of the electronic or molecular structures between the ground and excited states was evaluated by a comparison of the experimental radiative rate constant (k(r)) with the Strickler-Berg rate constant (kSB(r)). The electrochemical properties of 2a-f and 3a-f were determined by cyclic voltammetry, which demonstrated that these fluorescent dyes have similar HOMO energy levels, but different LUMO energy levels. Semi-empirical molecular orbital calculations (AM1 and INDO/S) have been carried out to elucidate the effects of the substituents and chromophore skeleton on photophysical properties of the two D-pi-A structural isomers. These studies indicated that the ICT characteristics in the excited state are different among the fluorescent dyes, which is a principal reason for the differences of the fluorescence solvatochromism and the substituent dependent fluorescence properties among the two D-pi-A structural isomers.
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