Excited-state intramolecular proton transfer and rotamerism of 2-(2′-hydroxyphenyl) benzimidazole

Theoretical Modelling for the Ground State Rotamerisation and Excited State Intramolecular Proton Transfer of 2-(2’-hydroxyphenyl)oxazole, 2-(2’-hydroxyphenyl)imidazole, 2-(2’-hydroxyphenyl)thiazole and Their Benzo Analogues

“…Hence, although the IPT process in infeasible in the ground state, the photoinduced proton transfer reaction is feasible in the S 1 and the T 1 states from both thermodynamic and kinetic reasons. The activation barriers from our calculations appear to be a little higher than the experimental values [11,16,25,27,37,48,53]. This deviation may be because of the fact that the short range specific interactions, like hydrogen bonding, have not been considered in the present work.…”

“…There is also a difference in the temporal behaviour of the fluorescence decay of the rotamer and the formation of the tautomer [18,39]. These evidences indicate that the electronic excitation of the species leads to the ESIPT product from only one of the two rotameric forms in selected solvents [23,25,27,28,[33][34][35]37,[39][40][41][42][43][44][45][46][47][48][49][50]. Mordzinski and Grellmann suggested that a thermally activated radiationless transition dominates the decay of the photoproduced keto form at room temperature, whereas, at lower temperature, fluorescence and intersystem crossing are the main deactivation processes [40].…”

“…They have also calculated the molecular geometry of the excited enol and keto forms using the MNDO methods [36]. Effect of rotamerism and hydrogen bonding on the ESIPT in HBO and HBI has also been studied using steadystate and time-resolved emission spectroscopy at various temperatures and by semi-empirical quantum mechanical methods like CNDO/SCI and AM1 [16,37].…”

Research of electronic absorption spectra of benzazols derivatives by ab initio calculations

“…Excited state intramolecular proton transfer and rotamerization of HBI have been studied using steady-state and time-resolved emission spectroscopy and also by semiempirical quantum chemical methods [17]. Picosecond spectroscopic studies have been performed on the excited state intramolecular proton transfer in HBT [23,24] where a change in the fluorometric behavior of the compound in different environmental conditions has been highlighted.…”

Tautomerization in the ground and first excited singlet states of phenyl-lapimidazole

“…Proton transfer is an area of wide interest due to its ubiquitous nature and recently many intramolecular proton transfer (IPT) reactions have been studied [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The advent of ultrafast spectroscopic methods has permitted kinetic studies on the nano-, pico-and femtosecond timescales [2][3][4].…”