Singlet excited-state intramolecular proton tranfer in 2-(2t'-hydroxyphenyl) benzoxazole: spectroscopy at low temperatures, femtosecond transient absorption, and MNDO calculations

Arthen-Engeland, T.; Bultmann, T.; Érnsting, N. P.; Rodrı́guez, Miguel A.; Thiel, Walter

doi:10.1016/0301-0104(92)80138-l

Cited by 204 publications

(119 citation statements)

References 26 publications

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“…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.…”

Section: Intramolecular Proton Transfercontrasting

confidence: 59%

“…For larger molecules semi-empirical molecular orbital methods are better compromise as they are some orders of magnitude faster than the ab initio method and give calculated results which agree with the experimental ones within acceptable limits [48][49][50][51][52][53].…”

Section: Quantum Chemical Calculationsmentioning

confidence: 99%

“…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].…”

Section: Introductionmentioning

confidence: 99%

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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

Purkayastha

Chattopadhyay

2003

IJMS

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Two series of compounds, one comprising of 2-(2′-hydroxyphenyl)benzoxazole (HBO), 2-(2′-hydroxyphenyl)benzimidazole (HBI), 2-(2′-hydroxyphenyl)benzothiazole (HBT), and the other of 2-(2′-hydroxyphenyl)oxazole (HPO), 2-(2′-hydroxyphenyl)imidazole (HPI) and 2-(2′-hydroxyphenyl)thiazole (HPT) are susceptible to ground state rotamerization as well as excited state intramolecular proton transfer (ESIPT) reactions. Some of these compounds show experimental evidence of the existence of two ground state conformers. Out of these two one undergoes ESIPT reaction leading to the formation of the tautomer. The two photophysical processes, in combination, result in the production of a number of fluorescence bands each one of which corresponding to a particular species. Semiempirical AM1-SCI calculations have been performed to rationalize the photophysical behaviour of the compounds. The calculations suggest that for the first series of compounds, two rotational isomers are present in the ground state of HBO and HBI while HBT has a single conformer under similar circumstances. For the molecules of the other series existence of rotamers depends very much on the polarity of the environment. The potential energy curves (PEC) for the ESIPT process in different electronic states of the molecules have been generated theoretically. The simulated PECs reveal that for all these systems the IPT reaction is unfavourable in the ground state but feasible, both kinetically and thermodynamically, in the S 1 as well as T 1 states.

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Section: Intramolecular Proton Transfercontrasting

confidence: 59%

Section: Quantum Chemical Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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

Purkayastha

Chattopadhyay

2003

IJMS

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“…Vibronic states closer to the S 1 origin are known to have a longer lifetime. 15,28 The proton transfer time of less than 50 fs presented for OHBA and for higher vibronic levels in HAN is very similar to the proton transfer rates of many related systems, e.g., methyl salicylate, 18 2-͑2Ј-hydroxyphenyl͒benzoxazole 33 and TINUVIN P 34 and may be a common time scale for direct ESIPT processes. The observation of signal oscillations by transient absorption experiments on 2-͑2Ј-hydroxyphenyl͒benzothiazole show that the ESIPT is mediated by deformations of the whole chelate ring, 35 in agreement with theoretical work.…”

mentioning

confidence: 56%

Dynamics of excited-state proton transfer systems via time-resolved photoelectron spectroscopy

Lochbrunner

Schultz

Schmitt

et al. 2001

The Journal of Chemical Physics

156

158

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We investigate the applicability of time-resolved photoelectron spectroscopy to excited state intramolecular proton transfer (ESIPT) and internal conversion dynamics in the model system o-hydroxybenzaldehyde (OHBA) and related compounds. Photoelectron spectra of both the excited state enol and keto tautomers were obtained as a function of pump laser wavelength and pump-probe time delay. The ESIPT was found to occur in less than 50 fs over the whole absorption range of the S1(ππ*) state for both OHBA and its monodeuterated analog, suggestive of a small or nonexistent barrier. The subsequent keto internal conversion rate in OHBA varies from 0.63 to 0.17 ps−1 over the S1(ππ*) absorption band and the OD-deuterated analog shows no significant isotope effect. Based upon ab initio calculations and comparison with the two-ring analog, 1-hydroxy-2-acetonaphthone (HAN), we suggest that the internal conversion dynamics in OHBA is influenced by interactions with a close-lying nπ* state.

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“…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.…”

Section: Introductionmentioning

confidence: 99%

Photochemical and complexation studies for new fluorescent and colored chelator

Ohshima

Momotake

Arai

2005

Science and Technology of Advanced Materials

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The photo-induced intramolecular proton (or hydrogen atom) transfer (ESIPT) and metal binding properties of Oxa-ester were studied in methanol solution. The dissociation constant between Oxa-ester and the metal ion was highly dependent with the metal ion and was determined by Hill plots or iterative least squares fitting to be 447 mM, 14.9 mM, and 290 nM for Ca 2C , Zn 2C , and Cu 2C , respectively, in methanol. The fluorescence intensity of Oxa-ester greatly increased with increasing concentration of Zn 2C , while the fluorescence intensity decreased with the addition of Ca 2C and Cu 2C . Transient absorption spectroscopy revealed that Oxa-ester underwent ESIPT to give Z-NH isomer in the excited state in benzene, while Oxa did not undergo ESIPT probably due to the hydrogen bonding with solvent water. q

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Singlet excited-state intramolecular proton tranfer in 2-(2t'-hydroxyphenyl) benzoxazole: spectroscopy at low temperatures, femtosecond transient absorption, and MNDO calculations

Cited by 204 publications

References 26 publications

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

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

Dynamics of excited-state proton transfer systems via time-resolved photoelectron spectroscopy

Photochemical and complexation studies for new fluorescent and colored chelator

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