Transient absorption and two-step laser excitation fluorescence studies of photoisomerization in 2-(2-hydroxyphenyl)benzoxazole and 2-(2-hydroxyphenyl)benzothiazole

Photoisomerization of 2-(2'-Hydroxyphenyl)benzoxazole. Formation and Decay of the Trans-Keto Tautomer in Dry and in Water-Containing 3-Methylpentane

“…This value is very close to z, = 0.26 ps found, as mentioned above, by Itoh and Fujiwara. 2 We therefore presume that the 3MP solution investigated in ref 2 contained traces of water. This would imply that the absorption and, in two-step-laser-excitation (TSLE) experiments, the emission of the proton-quenched trans-keto tautomer had been observed2 and not that of the cis-keto tautomer.…”

Time-dependent density functional theory study on excited state intramolecular proton transfer of 3-hydroxy-2-(pyridin-2-yl)-4H-chromen-4-one

“…Excited state intramolecular proton transfer (ESIPT) is one type of proton transfer reaction that has been investigated in the past few decades [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] and has been of considerable interest. It is generally believed that the ESIPT process involves the transfer of a hydroxyl (or amino) proton to an acceptor in the excited state, giving rise to the proton transfer tautomer emission.…”

“…This process occurs in many systems. For example, 3-hydroxyflavone (3-HF) derivatives displayed dual fluorescence with two highly resolved emission bands resulting from ESIPT [1]; Barbara et al [2] and Itoh and Fujiwara [3] found that the ESIPT of 2-(2-hydroxyphenyl) benzothiazole takes place in less than a few picoseconds; ESIPT could also respond to microenvironment polarity through two well-separated bands in the emission spectra of 3-hydroxychromones [7]. The reaction path of ESIPT of benzotriazole was nonplanar and charge-transfer from phenol to triazole group triggered adiabatic proton transfer [8].…”

Photochemical and complexation studies for new fluorescent and colored chelator

“…Oxa and Oxa-ester have metal binding moieties and photoresponsive 2-(2 0 -hydroxyphenyl)benzoxazole (HBO) skeleton in its structure. HBO is well known as a typical molecule, which undergoes excited state intramolecular proton-transfer (ESIPT) [28][29][30][31][32][33][34][35][36][37][38][39][40][41]. Thus, the produced tautomer has different electronic structure and may have a considerably different binding constant with cations.…”