Direct observation of fast proton transfer: femtosecond photophysics of 3-hydroxyflavone

Schwartz, Benjamin J.; Peteanu, Linda A.; Harris, Charles B.

doi:10.1021/j100188a009

Cited by 277 publications

(259 citation statements)

References 0 publications

Supporting

Mentioning

235

Contrasting

Unclassified

Order By: Relevance

“…4 and 6). The time scale is similar to those found in other systems in the gas phase (14) or in solution (23)(24)(25). A barrierless mechanism (14) was proposed and supported by theoretical calculations (26,27).…”

Section: Directed Dynamics In Confined Geometry: Intramolecular Protonsupporting

confidence: 82%

Femtosecond Studies of Protein-Ligand Hydrophobic Binding and Dynamics: Human Serum Albumin

Douhal

Zhong

Zewail

2002

Femtochemistry and Femtobiology

View full text Add to dashboard Cite

Section: Directed Dynamics In Confined Geometry: Intramolecular Protonsupporting

confidence: 82%

Femtosecond Studies of Protein-Ligand Hydrophobic Binding and Dynamics: Human Serum Albumin

Douhal

Zhong

Zewail

2002

Femtochemistry and Femtobiology

View full text Add to dashboard Cite

“…47 In addition, the presence of a hydrogen-bonding impurity might complicate the excited-state dynamics. 48 The fluorescence upconversion decay trace of curcumin in chloroform is shown in Figure 3c. The decay trace is best fitted with a single-exponential decay function with a time constant of 130 ( 20 ps.…”

Section: Resultsmentioning

confidence: 99%

Excited-State Intramolecular Hydrogen Atom Transfer and Solvation Dynamics of the Medicinal Pigment Curcumin

et al. 2009

View full text Add to dashboard Cite

The potential use of the naturally occurring yellow-orange pigment curcumin as a photodynamic therapy agent is one of the most exciting applications of this medicinal compound. Although subnanosecond spectroscopy has been used to investigate the photophysical processes of curcumin, the time resolution is insufficient to detect important and faster photoinduced processes, including solvation and excited-state intramolecular hydrogen atom transfer (ESIHT). In this study, the excited-state photophysics of curcumin is studied by means of ultrafast fluorescence upconversion spectroscopy. The results show two decay components in the excited-state kinetics with time scales of 12−20 ps and ∼100 ps in methanol and ethylene glycol. The resulting prominent isotope effect in the long component upon deuteration indicates that curcumin undergoes ESIHT in these solvents. The short component (12−20 ps) is insensitive to deuteration, and multiwavelength fluorescence upconversion results show that this decay component is due to solvation of excited-state curcumin. KeywordsAtomic spectroscopy, deuterium, ethylene, ethylene glycol, fluorescence, free radical reactions, hydrogen, methanol, photodynamic therapy, solvation, curcumin, decay components, deuteration, excited-state, fluorescence upconversion, intramolecular hydrogens, isotope effects, photophysics The potential use of the naturally occurring yellow-orange pigment curcumin as a photodynamic therapy agent is one of the most exciting applications of this medicinal compound. Although subnanosecond spectroscopy has been used to investigate the photophysical processes of curcumin, the time resolution is insufficient to detect important and faster photoinduced processes, including solvation and excited-state intramolecular hydrogen atom transfer (ESIHT). In this study, the excited-state photophysics of curcumin is studied by means of ultrafast fluorescence upconversion spectroscopy. The results show two decay components in the excited-state kinetics with time scales of 12-20 ps and ∼100 ps in methanol and ethylene glycol. The resulting prominent isotope effect in the long component upon deuteration indicates that curcumin undergoes ESIHT in these solvents. The short component (12-20 ps) is insensitive to deuteration, and multiwavelength fluorescence upconversion results show that this decay component is due to solvation of excited-state curcumin.

show abstract

“…Equilibrium parameters of different photoisomers of HBO, HBI, HBT and HPO, HPI, HPT in different electronic states. R [7][8][9][10][11][12][13][14][15][16][17] represents the interatomic distance between the two atoms for the first series and R [8][9][10][11][12][13] represents it for the other series referred to by the numbers (see Scheme 1). T 7-8-10-11 is the torsional angle developed by the atoms of the first series and T 2-1-7-8 is that developed by those of the second series.…”

Section: Resultsmentioning

confidence: 99%

“…The Franck-Condon excited state of the molecule is very close to the intersection zone of the potential energy surfaces of the two prototropic species. Thus, upon excitation, the molecule passes to the potential well of the tautomeric species almost instantaneously and then relaxes vibrationally [17][18][19][20][21]. The tautomeric transformation barrier is very low; greater than the energies of the lowest frequency vibrations but similar to, or smaller than those of the stretching modes of the concerned compound skeleton.…”

Section: Introductionmentioning

confidence: 99%

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

View full text Add to dashboard Cite

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.

show abstract

Direct observation of fast proton transfer: femtosecond photophysics of 3-hydroxyflavone

Cited by 277 publications

References 0 publications

Femtosecond Studies of Protein-Ligand Hydrophobic Binding and Dynamics: Human Serum Albumin

Femtosecond Studies of Protein-Ligand Hydrophobic Binding and Dynamics: Human Serum Albumin

Excited-State Intramolecular Hydrogen Atom Transfer and Solvation Dynamics of the Medicinal Pigment Curcumin

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

Contact Info

Product

Resources

About