The spectra of 2,5-bis( 2-benzoxazolyl)hydroquinone (BBXHQ) in solid argon at IS K reveals two species. The major species (96%) undergoes very efficient excited-state intramolecular proton transfer (ESIPT) after excitation to S,. It is assigned to the isolated BBXHQ molecule (solvated by argon atoms) in which ESIPT is not thermally activated. Either no energy barrier exists or it can be overcom...

Hypocrellin A displays photoinduced antiviral activity, in particular against the human immunodeficiency virus (HIV), as does its counterpart, hypericin. Although hypocrellin A, like hypericin, executes an excited-state intramolecular proton transfer, it differs from hypericin in two important ways. Unlike hypericin, hypocrellin A absolutely requires oxygen for its antiviral activity. Also, whe...

J. Phys. Or es (SADs) in aqueous solutions was investigated in a wide range of pH by time-correlated single photon counting (lex1⁄4 350nm, tresp1⁄4 300ps) and fluorescence up-conversion (lex1⁄4 266nm, tresp1⁄4 300 fs) techniques. The acid–base equilibrium constants in the ground (pKa) and the excited states (pK a ), the fluorescence quantum yields as well as the lifetimes of anionic, neutral, a...

In their Review (article number 2001952), Ling Chen, Peng-Yan Fu, Mei Pan and co-workers give a summary introduction of ESIPT (excited state intramolecular proton transfer) materials in the solid including small organic molecules, metal-organic frameworks covalent-organic frameworks. The four-leveled energy cycle based keto-enol emissions these respond to temperature, pressure, solvent, ions, l...

It is shown that owing to a dominance of np−pair transfer mechanism of backward elastic p Hescattering for incident proton kinetic energies Tp > 1 GeV the cross section of this process is defined mainly by the values of the Faddeev component of the wave function of He nucleus, φ(q23,p1), at high relative momenta q23 > 0.6GeV/c of the NN-pair in the S0− state and at low spectator momenta p1 ∼ 0−...

Herein, three environment-sensitive (solvatochromic) fluorescent dyes presenting a strong electron acceptor 3-methoxychromone unit and varied electron donor 2-aryl were developed. All three dyes showed remarkable polarity-dependent shifts of the emission maximum, which increase with extension of the dye conjugation. For the 3-methoxychromone bearing a 7-(diethylamino)-9,9-dimethylfluoren-2-yl d...

The semi-empirical tight-binding methods GFN1-xTB and GFN2-xTB are applied to calculations of structure, energy normal vibrations the molecule 2-(2'-hydroxyphenyl)benzoxazole undergoing excited state intramolecular proton transfer. results compared with ones obtained by density-functional hydrogen interaction corrections density functional theory. method is found provide good correspondence mor...