Proton transfer and internal conversion of o-hydroxybenzaldehyde: coherent versus statistical excited-state dynamics

Stock, Kai; Bizjak, T.; Lochbrunner, Stefan

doi:10.1016/s0009-2614(02)00152-5

Cited by 71 publications

(75 citation statements)

References 26 publications

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“…In a recent preliminary communication of the present work, we located not only an S 2 /S 1 conical intersection but also a three-state conical intersection where S 0 , S 1 , and S 2 are simultaneously degenerate. 24 Although there have been a number of femtosecond timeresolved spectroscopic studies of ESIPT systems such as o-hydroxybenzaldehyde (OHBA) 25, 26 and methyl salicylate (MS), 27 none have yet been reported for MA. Observed time scales for ESIPT have been reported as 45 (OHBA) and e60 (MS) fs.…”

Section: Figurementioning

confidence: 99%

Ab Initio Molecular Dynamics of Excited-State Intramolecular Proton Transfer around a Three-State Conical Intersection in Malonaldehyde

2005

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Excited-state potential energy surface (PES) characterization is carried out at the CASSCF and MRSDCI levels, followed by ab initio dynamics simulation of excited-state intramolecular proton transfer (ESIPT) on the S2(pipi*) state in malonaldehyde. The proton-transfer transition state lies close to an S2/S1 conical intersection, leading to substantial coupling of proton transfer with electronic relaxation. Proton exchange proceeds freely on S2, but its duration is limited by competition with twisting out of the molecular plane. This rotamerization pathway leads to an intersection of the three lowest singlet states, providing the first detailed report of ab initio dynamics around a three-state intersection (3SI). There is a significant energy barrier to ESIPT on S1, and further pyramidalization of the twisted structure leads to the minimal energy S1/S0 intersection and energetic terminal point of excited-state dynamics. Kinetics and additional mechanistic details of these pathways are discussed. Significant depletion of the spectroscopic state and recovery of the ground state is seen within the first 250 fs after photoexcitation.

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Section: Figurementioning

confidence: 99%

Ab Initio Molecular Dynamics of Excited-State Intramolecular Proton Transfer around a Three-State Conical Intersection in Malonaldehyde

2005

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“…The generic model for the mechanistic function of photostabilizers involves barrierless enol-to-keto proton (or hydrogen) transfer in the excited state, ultrafast (E100 fs) radiationless decay of the excited keto form, as well as barrierless hydrogen back-transfer in the electronic ground state, thus closing the photocycle. [3][4][5][6] While the spectroscopic and kinetic measurements for SA, MS and OHBA indicate a barrierless proton (or hydrogen) transfer process in the excited state, [9][10][11][12][13] early electronic structure calculations based on semiempirical methods or simple ab initio methods without inclusion of electron correlation predicted sizeable barriers. More recent calculations based on more sophisticated electronic structure methods such as CASPT2 (second-order perturbation theory based on the complete active space self-consistent field (CASSCF) reference), CC2 (a simplified and cost-efficient variant of singlesand-doubles coupled cluster theory) or TDDFT (time-dependent density functional theory) consistently predicted extremely flat and barrierless energy profiles along the minimum energy reaction path for intramolecular hydrogen transfer.…”

Section: Introductionmentioning

confidence: 99%

Photophysics of intramolecularly hydrogen-bonded aromatic systems: ab initio exploration of the excited-state deactivation mechanisms of salicylic acid

Sobolewski

Domcke

2006

Phys. Chem. Chem. Phys.

134

122

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Excited state reaction paths and the corresponding energy profiles of salicylic acid have been determined with the CC2 method, which is a simplified version of singles-and-doubles coupled cluster theory. At crucial points of the potential energy hypersurfaces, single-point energy calculations have been performed with the CASPT2 method (second-order perturbation theory based on the complete active space self-consistent field reference). Hydrogen transfer along the intramolecular hydrogen bond as well as torsion and pyramidization of the carboxy group have been identified as the most relevant photochemical reaction coordinates. The keto-type planar S(1) state reached by barrierless intramolecular hydrogen transfer represents a local minimum of the S(1) energy surface, which is separated by a very low barrier from a reaction path leading to a low-lying S(1)-S(0) conical intersection via torsion and pyramidization of the carboxy group. The S(1)-S(0) conical intersection, which occurs for perpendicular geometry of the carboxy group, is a pure biradical. From the conical intersection, a barrierless reaction path steers the system back to the two known minima of the S(0) potential energy surface (rotamer I, rotamer II). A novel structure, 7-oxa-bicyclo[4.2.0]octa-1(6),2,4-triene-8,8-diol, has been identified as a possible transient intermediate in the photophysics of salicylic acid.

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“…Fluorescence of salicylaldehyde [25] and 2-(2-hydroxyphenyl)imidazo-[1,2-a]pyridine analogues [23,24] exhibiting hydrogen bonding similar to that shown between the salicylaldimino nitrogen and phenolic proton in Scheme I, have been reported to involve excited state intramolecular proton transfer [23,24], in which the nitrogen atom (oxygen atom in the case of salicylaldehyde) serves as a proton acceptor during the fluorescing process. As neither of the amideamine precursors was noted to fluoresce, the fluorescence exhibited by the title compounds is likely due entirely to the salicylaldimine moiety.…”

Section: Resultsmentioning

confidence: 94%

“…While fluorescence has been observed for 2,2'-biimidazole and a few of its derivatives [20][21][22], fluorescence of the biimidazole amide-amine precursors for the title compounds was not observed to an appreciable degree. However, fluorescence of salicylaldehyde is well known and occurs in the yellow-green region of the spectrum [25], precisely the region over which the title compounds fluoresce.…”

Section: Introductionmentioning

confidence: 99%

Syntheses and fluorescence of salicylaldimine schiff base derivatives of 1,1′‐di(aminoethylaminocarbonylalkyl)‐2,2′‐biimidazole

Barnett

Carr

Counsil

et al. 2008

Journal of Heterocyclic Chem

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The amide‐amine, 1,1′‐di(aminoethylaminocarbonylethyl)‐2,2′‐biimidazole (DAEPB) (1), and subsequent Schiff base imine product, 1,1′‐di(salicylaldiminoethylaminocarbonylethyl)‐2,2′‐biimidazole (DSEB) (2a), have been synthesized from the ester, 1,1′‐di(ethoxycarbonylethyl)‐2,2′‐biimidazole (DEPB). Additionally, 1,1′‐di(salicylaldiminoethylaminocarbonylmethyl)‐2,2′‐biimidazole (DSMB) (2b), was prepared from its corresponding amide‐amine. All compounds were characterized with FTIR, NMR and elemental analyses. The salicylaldimines, compounds (2a) and (2b), exhibit fluorescence at 540 and 520 nm, respectively, over a broad range of excitation wavelengths.

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Proton transfer and internal conversion of o-hydroxybenzaldehyde: coherent versus statistical excited-state dynamics

Cited by 71 publications

References 26 publications

Ab Initio Molecular Dynamics of Excited-State Intramolecular Proton Transfer around a Three-State Conical Intersection in Malonaldehyde

Ab Initio Molecular Dynamics of Excited-State Intramolecular Proton Transfer around a Three-State Conical Intersection in Malonaldehyde

Photophysics of intramolecularly hydrogen-bonded aromatic systems: ab initio exploration of the excited-state deactivation mechanisms of salicylic acid

Syntheses and fluorescence of salicylaldimine schiff base derivatives of 1,1′‐di(aminoethylaminocarbonylalkyl)‐2,2′‐biimidazole

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