Excited-state proton transfer to solvent of protonated aniline derivatives in aqueous solution: a remarkable effect of ortho alkyl group on the proton-dissociation rate

Shiobara, Satoru; Kamiyama, Rie; Tajima, So; Shizuka, Haruo; Tobita, Seiji

doi:10.1016/s1010-6030(02)00310-6

Cited by 13 publications

(10 citation statements)

References 53 publications

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“…Excited-state proton dissociation in aqueous solutions has also been reported for protonated Chemical Physics Letters 380 (2003) 673-680 www.elsevier.com/locate/cplett amino arenes [14][15][16][17]. The acid-base equilibria of aniline derivatives (ANs) in the ground and excited singlet states are shown in Fig.…”

Section: Introductionmentioning

confidence: 84%

“…These values were estimated using the pK a value in the ground state and absorption and fluorescence data, taking into account the energy difference ðDG solv Þ between the Franck-Condon state and the equilibrium state [14,15]. The DG solv for the proton-dissociation reactions in the ground and S 1 states were estimated by assuming that the energy difference between the absorption and fluorescence energies (Stokes shift) is equal to twice the DG solv if the two harmonic potential surfaces are the same and symmetrical [32] hm a À hm…”

Section: Thermochemical Considerationsmentioning

confidence: 99%

“…Such structural change of the amino group in the S 1 state results in charge migration from the amino group to the benzene ring, leading to enhancement of the acidity of its protonated form in the excited state [20]. In fact we have recently found that protonated aniline (ANH þ ) and its derivatives (ANsH þ ) in aqueous solutions undergo very fast excited-state proton dissociation [14,15]. Since the intramolecular charge transfer character of AN should be influenced by a substituent on the aromatic ring, it is expected that the acidity of ANs in the S 1 state is modified significantly depending on the electronic character of the substituent.…”

Section: Introductionmentioning

confidence: 99%

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Substituent effects on ultrafast excited-state proton transfer of protonated aniline derivatives in aqueous solution

Shiobara¹,

Tajima²,

Tobita³

2003

Chemical Physics Letters

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Section: Introductionmentioning

confidence: 84%

Section: Thermochemical Considerationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Substituent effects on ultrafast excited-state proton transfer of protonated aniline derivatives in aqueous solution

Shiobara¹,

Tajima²,

Tobita³

2003

Chemical Physics Letters

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“…A comparison of the time of protonation/deprotonation with the lifetime of emission is needed. The lifetime of luciferin fluorescence is approximately 10 À9 s (16), whereas the time of protonation or deprotonation of organic molecules is 10 À10 -10 À9 s (33,34). These evaluations suggest that a single protonation or deprotonation event could occur before emission, whereas two or more protons coordinating or dissociating in S 1 rarely occur.…”

Section: Methodsmentioning

confidence: 99%

Analysis of Photoexcitation Energy Dependence in the Photoluminescence of Firefly Luciferin

Hiyama

Akiyama

Mochizuki

et al. 2014

Photochem & Photobiology

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The whole pathways for photoluminescence, which include absorption, relaxation and emission, of firefly luciferin in aqueous solutions of different pH values with different photoexcitation energies were theoretically investigated by considering protonation/deprotonation. It is experimentally known that the color of fluorescence changes from green to red with a decrease in the photoexcitation energy. We confirmed with the theoretical analysis that the peak energy shift in the fluorescence spectra with varying photoenergies is due to a change in photoluminescence pathway. When the photoexcitation energy is decreased, the red emission from a monoanion form of firefly luciferin with carboxylate and phenolate groups and N-protonated thiazoline ring occurs irrespective of the pH values. However, because the species abundant in the solution and those excited by the photon depend on the solution pH, the pathway leading to the monoanion form changes with the solution pH.

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“…This dynamic process accompanies the decay tail of the fluorescence of the parent photoacid, according to a power law, t −d . In this study, N ‐methyl‐7‐hydroxyquinolinium ion was carefully chosen because its deprotonated form is neutral, so there exists much weaker ion–dipole interaction to the dissociated proton with negligible (or weak) geminate recombination . This strategy allows straightforward interpretation of simpler dynamics.…”

Section: Methodsmentioning

confidence: 99%

Alcohol Dimer is Requisite to Form an Alkyl Oxonium Ion in the Proton Transfer of a Strong (Photo)Acid to Alcohol

Park

Lee

Kwac

et al. 2016

Chemistry A European J

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What was the inspiration for this cover design? When we were invited to submit ac over suggestion, we were seeking an intuitive way to represent the key finding of this study: the basicity enhancement of an alcohol by hydrogen-bonded clustering. As such, we used at wo-pan balance, which "weighs" the basicity of ac lustered alcohol versus as ingle alcohol molecule, in the pk a scale, to highlight their difference. Is your current researchm ainly curiosity driven (fundamental) or rather applied? Our current research is basically curiosity driven. The role of the hydrogen bond network of water has been extensively investigated and, in many aspects, its importance can never be underestimated, in terms of structure, dynamics, and function in chemistry and biology .W eh ave also sought to understand how the hydrogen-bonded network of water is arranged and affects the energetics and dynamics of aqueous acid-base reactions by using photo-chemistry and photophysics. The motivation of this work, in particular ,w as the observation that the photoinduced proton transfer can also occur in alcohol with ap roperly chosen photoacid, yet this issue of proton transfer to alcohol is (perhaps surprisingly) poorly understood in the literature and textbooks, although this simple reaction is directly related to acid catalysis in alcohol dehydration , for example. Therefore, in this project, we were interested in understanding this very basic acid-base chemistry involving alcohol , which has not been considered in many organic chemistry textbooks. What other topics are you working on at the moment? Besides the current research in understanding the molecular mechanisms in acid-base reactions utilizing time-resolved spectroscopy, we are also very interested in studying structural dynamics in higher architectures made of small molecular entities, such as metal-organic frameworks and protein complexes. To this end, we are working on building ah igh-end time-resolved electron microscope at UNIST,w hich is now at the final phase of setting up. With the combination of electronic spectroscopy and structural imaging in space and time, we hope to extend our journey to understand various chemical and materials phenomena from am olecular level to amesoscopic level, where communication between constituents plays asignificant role in function. Invited for the cover of this issue is the group of Oh-Hoon Kwon at the Ulsan National Institute of Science and Technology and the Institutef or Basic Science in Ulsan. The image depicts at wo-pan balance representingt he enhancemento fa na lco-hol'sb asicity by hydrogen-bonded clustering, as investigatedb yt ime-resolved fluorescence quenching of as trong Brønsted photoacid. Read the full text of the article at

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Excited-state proton transfer to solvent of protonated aniline derivatives in aqueous solution: a remarkable effect of ortho alkyl group on the proton-dissociation rate

Cited by 13 publications

References 53 publications

Substituent effects on ultrafast excited-state proton transfer of protonated aniline derivatives in aqueous solution

Substituent effects on ultrafast excited-state proton transfer of protonated aniline derivatives in aqueous solution

Analysis of Photoexcitation Energy Dependence in the Photoluminescence of Firefly Luciferin

Alcohol Dimer is Requisite to Form an Alkyl Oxonium Ion in the Proton Transfer of a Strong (Photo)Acid to Alcohol

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