Ultrafast dynamics of gas-phase excited-state intramolecular proton transfer in 1-hydroxy-2-acetonaphthone

Excited-state vibrational relaxation and deactivation dynamics of trans-4-(N,N-dimethylamino)-4′-nitrostilbene in nonpolar solvents studied by ultrafast time-resolved broadband fluorescence spectroscopy

“…Assuming 1 t* is the only emitting species, the kinetic model indeed predicts a biexponential decay with two compounded rate constants, k a and k b [46]. If the equilibrium between 1 t* and 1 p* is established much faster than the decay of both species, i.e., k 1 + k À1 >> k t or k p , then k a % k 1 + k À1 and k b % ðkt ÀkpÞ 2 [46]. Such approximation is well justified because t a << t b in the present case.…”

“…dynamics of emissive species; the production of dark triplet states and their subsequent relaxations are based on previous photochemical studies [17][18][19]. Assuming 1 t* is the only emitting species, the kinetic model indeed predicts a biexponential decay with two compounded rate constants, k a and k b [46]. If the equilibrium between 1 t* and 1 p* is established much faster than the decay of both species, i.e., k 1 + k À1 >> k t or k p , then k a % k 1 + k À1 and k b % ðkt ÀkpÞ 2 [46].…”

An abnormally slow proton transfer reaction in a simple HBO derivative due to ultrafast intramolecular-charge transfer events

“…The excited-state intramolecular proton transfer (ESIPT) reaction involving hydrogen atom (or proton) donor and acceptor groups within the same molecule generally takes place in very short time (o100 fs) via preformed intramolecular hydrogen bonds (IHBs). [2][3][4][5][6][7][8][9][10] When the donor and acceptor sites do not meet the geometrical requirements of an IHB, a H-bonding solvent may play the role of a proton-relay, and the excited-state intramolecular proton transfer is then assisted by the solvent molecules. During the last three decades, excited-state proton-transfer dyes have been much studied, leading to their different applications as fluorescent chemosensors, 11,12 laser dyes, [13][14][15][16][17] UV photostabilizers 18 and promising components for photoswitches, [19][20][21][22] and organic optoelectronic materials.…”

Slow excited state phototautomerization in 3-hydroxyisoquinoline

“…For the aromatic molecules which contain proton donor and acceptor sites, transfer of protons from the donor to the acceptor group in the excited state can occur in the gas phase and also in the condensed phase depending upon the surrounding medium/solvent. [1][2][3][4][5] In general, ESIPT reactions are believed to be very fast (occurring on the femtosecond scale); [6][7][8] however, in some cases slower ESIPT has been reported. 9 In the case of aprotic solvents or in the gaseous phase, direct excited state intramolecular proton transfer (ESIPT) can occur.…”