1
|
Hunt JR, Hecht J, Goolsby C, Hagihara J, Loza M, del Pozo S. Excited State Proton Transfer from Acidic Alcohols to a Quinoline Photobase Can Be Solvated by Non-Acidic Alcohol Solvents. J Phys Chem A 2024; 128:6199-6207. [PMID: 39034730 PMCID: PMC11299183 DOI: 10.1021/acs.jpca.4c02907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 06/25/2024] [Accepted: 07/11/2024] [Indexed: 07/23/2024]
Abstract
Photobases are a type of molecule that become more basic upon photoexcitation and can therefore be used to control proton transfer reactions with light. The solvation requirements for excited state proton transfer (ESPT) in photobase systems is poorly understood, which limits their applicability. Here, we investigate the solvation of the ESPT reaction using 5-methoxyquinoline (MeOQ), a well-studied photobase with an excited state pKa (pKa*) of approximately 15.1, as a model system. Previous studies have shown that, in addition to the acidic donor that donates a proton to the photoexcited MeOQ, an additional "auxiliary donor" is necessary to solvate the resulting alkoxide. We investigate whether a nonacidic hydrogen bond donor (an alcohol solvent that MeOQ cannot deprotonate in bulk) can act as the auxiliary donor for the MeOQ ESPT reaction. First, we use steady state spectroscopy, TCSPC, and electronic structure calculations to show that MeOQ can deprotonate the acidic donor 2,2,2-trifluoroethanol (TFE, pKa = 12.5) using ethanol as the auxiliary donor. We show that the degree of ESPT is largely predicted by the degree of ground state hydrogen bonding between the photobase and the acidic donor. Next, we study the deprotonation of the acidic donors TFE and 1,1,1,3,3,3-hexafluoroisopropanol (HFIP, pKa = 9.3) with MeOQ in a variety of nonacidic alcohol solvents of varying chain length and branching. MeOQ ESPT occurs to varying extents in all solvents, suggesting that all studied nonacidic alcohols can function as auxiliary donors. We show that the concentration of the acidic donor is strongly correlated with the degree of ESPT. These results are necessary fundamental steps toward the understanding of the photobase ESPT reaction and its wide application in a variety of chemical systems.
Collapse
Affiliation(s)
- Jonathan Ryan Hunt
- Loyola Marymount University, Los Angeles, California 90045, United States
| | - Joseph Hecht
- Loyola Marymount University, Los Angeles, California 90045, United States
| | - Clara Goolsby
- Loyola Marymount University, Los Angeles, California 90045, United States
| | - Jade Hagihara
- Loyola Marymount University, Los Angeles, California 90045, United States
| | - Monique Loza
- Loyola Marymount University, Los Angeles, California 90045, United States
| | - Samantha del Pozo
- Loyola Marymount University, Los Angeles, California 90045, United States
| |
Collapse
|
2
|
Bhide R, Phun GS, Ardo S. Elementary Reaction Steps That Precede or Follow a Unimolecular Reaction Step Can Obfuscate Interpretation of the Driving-Force Dependence to Its Rate Constant. J Phys Chem A 2024; 128:4177-4188. [PMID: 38752741 DOI: 10.1021/acs.jpca.3c08228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Assessing the validity of a driving-force-dependent kinetic theory for a unimolecular elementary reaction step is difficult when the observed reaction rate is strongly influenced by properties of the preceding or following elementary reaction step. A well-known example occurs for bimolecular reactions with weak orbital overlap, such as outer-sphere electron transfer, where bimolecular collisional encounters that precede a fast unimolecular electron-transfer step can limit the observed rate. A lesser-appreciated example occurs for bimolecular reactions with stronger orbital overlap, including many proton-transfer reactions, where equilibration of an endergonic unimolecular proton-transfer step results in a relatively small concentration of reaction products, thus slowing the rate of the following step such that it becomes rate limiting. Incomplete consideration of these points has led to discrepancies in interpretation of data from the literature. Our reanalysis of these data suggests that proton-transfer elementary reaction steps have a nonzero intrinsic free energy barrier, implying, in the parlance of Marcus theory, that there is non-negligible nuclear reorganization. Outcomes from our analyses are generalizable to inner-sphere electron-transfer reactions such as those involved in (photo)electrochemical fuel-forming reactions.
Collapse
Affiliation(s)
- Rohit Bhide
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Gabriel S Phun
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Shane Ardo
- Department of Chemistry, University of California Irvine, Irvine, California 92697, United States
- Department of Chemical & Biomolecular Engineering, University of California Irvine, Irvine, California 92697, United States
- Department of Materials Science & Engineering, University of California Irvine, Irvine, California 92697, United States
| |
Collapse
|
3
|
Yucknovsky A, Amdursky N. Controlling pH-Sensitive Chemical Reactions Pathways with Light - a Tale of Two Photobases: an Arrhenius and a Brønsted. Chemistry 2023:e202303767. [PMID: 38084008 DOI: 10.1002/chem.202303767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Indexed: 12/22/2023]
Abstract
Light-gated chemical reactions allow spatial and temporal control of chemical processes. Here, we suggest a new system for controlling pH-sensitive processes with light using two photobases of Arrhenius and Brønsted types. Only after light excitation do Arrhenius photobases undergo hydroxide ion dissociation, while Brønsted photobases capture a proton. However, none can be used alone to reversibly control pH due to the limitations arising from excessively fast or overly slow photoreaction timescales. We show here that combining the two types of photobases allows light-triggered and reversible pH control. We show an application of this method in directing the pH-dependent reaction pathways of the organic dye Alizarin Red S simply by switching between different wavelengths of light, i. e., irradiating each photobase separately. The concept of a light-controlled system shown here of a sophisticated interplay between two photobases can be integrated into various smart functional and dynamic systems.
Collapse
Affiliation(s)
- Anna Yucknovsky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 3200003, Israel
| | | |
Collapse
|
4
|
Codescu MA, Kunze T, Weiß M, Brehm M, Kornilov O, Sebastiani D, Nibbering ETJ. Ultrafast Proton Transfer Pathways Mediated by Amphoteric Imidazole. J Phys Chem Lett 2023; 14:4775-4785. [PMID: 37186569 DOI: 10.1021/acs.jpclett.3c00595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Imidazole, being an amphoteric molecule, can act both as an acid and as a base. This property enables imidazole, as an essential building block, to effectively facilitate proton transport in high-temperature proton exchange membrane fuel cells and in proton channel transmembrane proteins, enabling those systems to exhibit high energy conversion yields and optimal biological function. We explore the amphoteric properties of imidazole by following the proton transfer exchange reaction dynamics with the bifunctional photoacid 7-hydroxyquinoline (7HQ). We show with ultrafast ultraviolet-mid-infrared pump-probe spectroscopy how for imidazole, in contrast to expectations based on textbook knowledge of acid-base reactivity, the preferential reaction pathway is that of an initial proton transfer from 7HQ to imidazole, and only at a later stage a transfer from imidazole to 7HQ, completing the 7HQ tautomerization reaction. An assessment of the molecular distribution functions and first-principles calculations of proton transfer reaction barriers reveal the underlying reasons for our observations.
Collapse
Affiliation(s)
- Marius-Andrei Codescu
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Thomas Kunze
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Moritz Weiß
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Martin Brehm
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Oleg Kornilov
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Daniel Sebastiani
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Erik T J Nibbering
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| |
Collapse
|
5
|
Antalicz B, Versluis J, Bakker HJ. Observing Aqueous Proton-Uptake Reactions Triggered by Light. J Am Chem Soc 2023; 145:6682-6690. [PMID: 36940392 PMCID: PMC10064335 DOI: 10.1021/jacs.2c11441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2023]
Abstract
Proton-transfer reactions in water are essential to chemistry and biology. Earlier studies reported on aqueous proton-transfer mechanisms by observing light-triggered reactions of strong (photo)acids and weak bases. Similar studies on strong (photo)base-weak acid reactions would also be of interest because earlier theoretical works found evidence for mechanistic differences between aqueous H+ and OH- transfer. In this work, we study the reaction of actinoquinol, a water-soluble strong photobase, with the water solvent and the weak acid succinimide. We find that in aqueous solutions containing succinimide, the proton-transfer reaction proceeds via two parallel and competing reaction channels. In the first channel, actinoquinol extracts a proton from water, after which the newly generated hydroxide ion is scavenged by succinimide. In the second channel, succinimide forms a hydrogen-bonded complex with actinoquinol and the proton is transferred directly. Interestingly, we do not observe proton conduction in water-separated actinoquinol-succinimide complexes, which makes the newly studied strong base-weak acid reaction essentially different from previously studied strong acid-weak base reactions.
Collapse
Affiliation(s)
- Balázs Antalicz
- AMOLF, Ultrafast Spectroscopy, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Jan Versluis
- AMOLF, Ultrafast Spectroscopy, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Huib J Bakker
- AMOLF, Ultrafast Spectroscopy, Science Park 104, 1098 XG Amsterdam, The Netherlands
| |
Collapse
|
6
|
Ley C, Siedel A, Bertaux T, Croutxé-Barghorn C, Allonas X. Photochemical Processes of Superbase Generation in Xanthone Carboxylic Salts. Angew Chem Int Ed Engl 2023; 62:e202214784. [PMID: 36533332 DOI: 10.1002/anie.202214784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 12/16/2022] [Accepted: 12/16/2022] [Indexed: 12/23/2022]
Abstract
Photobase generators are species that allow the photocatalysis of various reactions, such as thiol-Michael, thiol-isocyanate, and ring-opening polymerization reactions. However, existing compounds have complex syntheses and low quantum yields. To overcome these problems, photobase generators based on the photodecarboxylation reaction were developed. We synthesized and studied the photochemistry and photophysics of two xanthone photobase, their carboxylic acid precursors, and their photoproducts to understand the photobase generation mechanism. We determined accurate quantum yields of triplet states and photobase generation. The effect of the intermediate radical preceding the base release was demonstrated. We characterized the photophysics of the photobase by femtosecond spectroscopy and showed that the photodecarboxylation process occurred from the second excited triplet state with a rate constant of 2.2×109 s-1 .
Collapse
Affiliation(s)
- Christian Ley
- Laboratoire de Photochimie et d'Ingénierie Macromoléculaire, Université de Haute Alsace, 3b rue A. Werner, 68200, Mulhouse, France
| | - Antoine Siedel
- Laboratoire de Photochimie et d'Ingénierie Macromoléculaire, Université de Haute Alsace, 3b rue A. Werner, 68200, Mulhouse, France
| | - Tony Bertaux
- Laboratoire de Photochimie et d'Ingénierie Macromoléculaire, Université de Haute Alsace, 3b rue A. Werner, 68200, Mulhouse, France
| | - Céline Croutxé-Barghorn
- Laboratoire de Photochimie et d'Ingénierie Macromoléculaire, Université de Haute Alsace, 3b rue A. Werner, 68200, Mulhouse, France
| | - Xavier Allonas
- Laboratoire de Photochimie et d'Ingénierie Macromoléculaire, Université de Haute Alsace, 3b rue A. Werner, 68200, Mulhouse, France
| |
Collapse
|
7
|
Bhide R, Feltenberger CN, Phun GS, Barton G, Fishman D, Ardo S. Quantification of Excited-State Brønsted-Lowry Acidity of Weak Photoacids Using Steady-State Photoluminescence Spectroscopy and a Driving-Force-Dependent Kinetic Theory. J Am Chem Soc 2022; 144:14477-14488. [PMID: 35917469 DOI: 10.1021/jacs.2c00554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photoacids and photobases constitute a class of molecules that upon absorption of light undergoes a reversible change in acidity, i.e. pKa. Knowledge of the excited-state pKa value, pKa*, is critical for predicting excited-state proton-transfer behavior. A reasonable approximation of pKa* is possible using the Förster cycle analysis, but only when the ground-state pKa is known. This poses a challenge for the study of weak photoacids (photobases) with less acidic (basic) excited states (pKa* (pKb*) > 7), because ground-state pKa (pKb) values are >14, making it difficult to quantify them accurately in water. Another method to determine pKa* relies on acid-base titrations with photoluminescence detection and Henderson-Hasselbalch analysis. This method requires that the acid dissociation reaction involving the thermally equilibrated electronic excited state reaches chemical quasi-equilibrium, which does not occur for weak photoacids (photobases) due to slow rates of excited-state proton transfer. Herein, we report a method to overcome these limitations. We demonstrate that liquid water and aqueous hydroxide are unique proton-accepting quenchers of excited-state photoacids. We determine that Stern-Volmer quenching analysis is appropriate to extract rate constants for excited-state proton transfer in aqueous solutions from a weak photoacid, 5-aminonaphthalene-1-sulfonate, to a series of proton-accepting quenchers. Analysis of these data by Marcus-Cohen bond-energy-bond-order theory yields an accurate value for pKa* of 5-aminonaphthalene-1-sulfonate. Our method is broadly accessible because it only requires readily available steady-state photoluminescence spectroscopy. Moreover, our results for weak photoacids are consistent with those from previous studies of strong photoacids, each showing the applicability of kinetic theories to interpret driving-force-dependent rate constants for proton-transfer reactions.
Collapse
Affiliation(s)
- Rohit Bhide
- Department of Chemistry, University of California─Irvine, Irvine, California 92697, United States
| | - Cassidy N Feltenberger
- Department of Chemistry, University of California─Irvine, Irvine, California 92697, United States
| | - Gabriel S Phun
- Department of Chemistry, University of California─Irvine, Irvine, California 92697, United States
| | - Grant Barton
- Department of Chemistry, University of California─Irvine, Irvine, California 92697, United States
| | - Dmitry Fishman
- Department of Chemistry, University of California─Irvine, Irvine, California 92697, United States.,Laser Spectroscopy Laboratories, University of California─Irvine, Irvine, California 92697, United States
| | - Shane Ardo
- Department of Chemistry, University of California─Irvine, Irvine, California 92697, United States.,Department of Chemical & Biomolecular Engineering, University of California─Irvine, Irvine, California 92697, United States.,Department of Materials Science & Engineering, University of California─Irvine, Irvine, California 92697, United States
| |
Collapse
|
8
|
Pandey N, Tewari N, Pant S, Mehata MS. Solvatochromism and estimation of ground and excited state dipole moments of 6-aminoquinoline. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 267:120498. [PMID: 34740005 DOI: 10.1016/j.saa.2021.120498] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 10/08/2021] [Accepted: 10/09/2021] [Indexed: 06/13/2023]
Abstract
The spectral behaviour of 6AQ was investigated using fluorescence spectroscopy in several polar and non-polar solvents. Both the absorption and fluorescence spectra displayed solvatochromism. The Stokes shift increased significantly with increasing solvent polarity and signifies a more polar excited state with possible change in the excited state (ES) geometry. The involvement of π→π∗ transition was observed. The ground state (GS) and excited state (ES) dipole moments were determined by the solvatochromic shift method using Bilot-Kawaski, Lippert-Mataga, Kawski-Chamma-Viallet, and Reichardt equations. The experimental value of GS dipole moment matches closely with the theoretical value computed using DFT/B3LYP/6-311G(d,p). The ES dipole moment is higher than the GS dipole moment. Besides, the solvatochromic study reveals that the ES of 6AQ is more polarized than the GS due to intramolecular charge transfer (ICT), possibly aided by a change in the geometry of the molecule in the ES. The influence of the non-specific and specific interactions in the photophysical properties of the titled molecule was analyzed using the Catalan scale. The study shows that 6AQ has reasonable band-gap energy and good CIE chromaticity coordinate in the blue region close to the national television standard committee system (NTSC) for the ideal blue CIE coordinate. Therefore, future research into 6AQ as a source of light-emitting diodes and fluorescent sensors may have potential applications in the field of optoelectronics.
Collapse
Affiliation(s)
- Nupur Pandey
- Photophysics Laboratory, Department of Physics, Centre of Advanced Study, DSB Campus, Kumaun University, Nainital 263002, Uttarakhand, India
| | - Neeraj Tewari
- Physics Department, Lajpat Rai College, Sahibabad, Ghaziabad 201005, U.P, India
| | - Sanjay Pant
- Photophysics Laboratory, Department of Physics, Centre of Advanced Study, DSB Campus, Kumaun University, Nainital 263002, Uttarakhand, India.
| | - Mohan Singh Mehata
- Laser-Spectroscopy Laboratory, Department of Applied Physics, Delhi Technological University, Delhi 110042, India.
| |
Collapse
|
9
|
Codescu MA, Weiß M, Brehm M, Kornilov O, Sebastiani D, Nibbering ETJ. Switching between Proton Vacancy and Excess Proton Transfer Pathways in the Reaction between 7-Hydroxyquinoline and Formate. J Phys Chem A 2021; 125:1845-1859. [PMID: 33651619 PMCID: PMC7957860 DOI: 10.1021/acs.jpca.0c10191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Bifunctional or amphoteric
photoacids simultaneously present donor
(acidic) and acceptor (basic) properties making them useful tools
to analyze proton transfer reactions. In protic solvents, the proton
exchange between the acid and the base is controlled by the acidity
or basicity strength and typically occurs on two different pathways
known as protolysis and hydrolysis. We report here how the addition
of a formate base will alter the relative importance of the possible
reaction pathways of the bifunctional photoacid 7-hydroxyquinoline
(7HQ), which has been recently understood to predominantly involve
a hydroxide/methoxide transport mechanism between the basic proton-accepting
quinoline nitrogen site toward the proton-donating OH group with a
time constant of 360 ps in deuterated methanol (CD3OD).
We follow the reaction dynamics by probing the IR-active marker modes
of the different charged forms of photoexcited 7HQ, and of formic
acid (HCOOD) in CD3OD solution. A comparison of the transient
IR spectra as a function of formate concentration, and classical molecular
dynamics simulations enables us to identify distinct contributions
of “tight” (meaning “contact”) and “loose”
(i.e., “solvent-separated”) 7HQ–formate reaction
pairs in our data. Our results suggest that depending on the orientation
of the OH group with respect to the quinoline aromatic ring system,
the presence of the formate molecule in a proton relay pathway facilitates
a net proton transfer from the proton-donating OH group of 7HQ-N*
via the methanol/formate bridge toward the quinoline N site.
Collapse
Affiliation(s)
- Marius-Andrei Codescu
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Moritz Weiß
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle Saale, Germany
| | - Martin Brehm
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle Saale, Germany
| | - Oleg Kornilov
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Daniel Sebastiani
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle Saale, Germany
| | - Erik T J Nibbering
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| |
Collapse
|
10
|
Photobase effect for just-in-time delivery in photocatalytic hydrogen generation. Nat Commun 2020; 11:5179. [PMID: 33056986 PMCID: PMC7560858 DOI: 10.1038/s41467-020-18583-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 08/17/2020] [Indexed: 11/09/2022] Open
Abstract
Carbon dots (CDs) are a promising nanomaterial for photocatalytic applications. However, the mechanism of the photocatalytic processes remains the subject of a debate due to the complex internal structure of the CDs, comprising crystalline and molecular units embedded in an amorphous matrix, rendering the analysis of the charge and energy transfer pathways between the constituent parts very challenging. Here we propose that the photobasic effect, that is the abstraction of a proton from water upon excitation by light, facilitates the photoexcited electron transfer to the proton. We show that the controlled inclusion in CDs of a model photobase, acridine, resembling the molecular moieties found in photocatalytically active CDs, strongly increases hydrogen generation. Ultrafast spectroscopy measurements reveal proton transfer within 30 ps of the excitation. This way, we use a model system to show that the photobasic effect may be contributing to the photocatalytic H2 generation of carbon nanomaterials and suggest that it may be tuned to achieve further improvements. The study demonstrates the critical role of the understanding the dynamics of the CDs in the design of next generation photocatalysts.
Collapse
|
11
|
Joung JF, Lee J, Hwang J, Choi K, Park S. A new visible light triggered Arrhenius photobase and its photo-induced reactions. NEW J CHEM 2020. [DOI: 10.1039/c9nj05404a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Visible light triggered Arrhenius photobases are of potential use for excited state hydroxide ion dissociation (ESHID), photo-induced pOH jump experiments, and base-catalyzed reactions.
Collapse
Affiliation(s)
- Joonyoung F. Joung
- Department of Chemistry and Research Institute for Natural Science
- Korea University
- Seoul
- Korea
| | - Jeeun Lee
- Department of Chemistry and Research Institute for Natural Science
- Korea University
- Seoul
- Korea
| | - Joungin Hwang
- Department of Chemistry and Research Institute for Natural Science
- Korea University
- Seoul
- Korea
| | - Kihang Choi
- Department of Chemistry and Research Institute for Natural Science
- Korea University
- Seoul
- Korea
| | - Sungnam Park
- Department of Chemistry and Research Institute for Natural Science
- Korea University
- Seoul
- Korea
| |
Collapse
|
12
|
Hunt JR, Dawlaty JM. Kinetic Evidence for the Necessity of Two Proton Donor Molecules for Successful Excited State Proton Transfer by a Photobase. J Phys Chem A 2019; 123:10372-10380. [PMID: 31710812 DOI: 10.1021/acs.jpca.9b08970] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photobases are molecules that convert light to proton transfer drive and therefore have potential applications in many areas of chemistry. Previously, we studied the photobasicity of quinolines and explored their applications. While it is possible to tether a photobase near a target proton donor, for the sake of versatility it is desirable to explore their capability to deprotonate molecules dispersed in a solution. Previous evidence suggested that in this scenario at least two proton donors were necessary for successful excited state proton transfer: one to donate a proton and the second to stabilize the photogenerated donor anion. Here we report kinetic evidence from transient absorption (TA) and time-correlated single photon counting (TCSPC) in support of this hypothesis. We used 5-methoxyquinoline as the photobase and 2,2,2-trifluoroethanol (TFE), a low pKa alcohol, as the proton donor. A constant concentration of the photobase was used for a range of proton-donor dilutions spanning several orders of magnitude in an aprotic background solvent. Absorption spectra confirm that over most of the studied range the majority of the photobase population is hydrogen bonded to at least one donor. Short-pulse TA was used to measure the faster (2-500 ps) dynamics, while TSCPC was used to measure the slower (>500 ps) dynamics. The measured proton transfer time constants varied as a function of donor concentration over a wide range. A log-log plot of the proton transfer rate constant as a function of proton-donor concentration shows two regimes: nondiffusive at high donor concentrations where multiple proton donors are near the photobase and diffusive at low donor concentrations where proton donors are more dilute. The nondiffusive regime has a slope of approximately one, suggesting that the proton transfer process is dependent on one donor molecule in addition to the donor molecule already hydrogen bonded with the photobase. The diffusive regime reasonably follows diffusion kinetics. We propose a model for how the second proton-donor molecule may interact with the photogenerated alkoxide to stabilize it. This work highlights the importance of inducing irreversible changes, in this case solvation of the alkoxide, after proton transfer. Understanding of such details is likely to be important in applications of photobases.
Collapse
Affiliation(s)
- Jonathan Ryan Hunt
- Department of Chemistry , University of Southern California , 920 Bloom Walk SSC 702 , Los Angeles , California 90089-0482 , United States
| | - Jahan M Dawlaty
- Department of Chemistry , University of Southern California , 920 Bloom Walk SSC 702 , Los Angeles , California 90089-0482 , United States
| |
Collapse
|
13
|
Hossen T, Sahu K. Effect of Photoacid Strength on Fluorescence Modulation of 2-Naphthol Derivatives inside β-Cyclodextrin Cavity: Insights from Fluorescence, Isothermal Calorimetry, and Molecular Dynamics Simulations. J Phys Chem B 2019; 123:9291-9301. [PMID: 31596595 DOI: 10.1021/acs.jpcb.9b05457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fluorescence response of a photoacid inside a confined environment often differs markedly from the bulk response. Is there any correlation between the extent of fluorescence modulation and the strength of the photoacid? Here, we used three photoacids: 2-naphthol (2OH, pKa* = 3.3), 6-sulfonate-2-naphthol (6SO3-2OH, pKa* = 3.06), and 6-cyano-2-naphthol (6CN-2OH, pKa* = 0.6) with remarkably different excited-state acidities to investigate fluorescence modulation inside the nanocavity of β-cyclodextrin (β-CD). Interestingly, we found strong fluorescence modulation for 2OH and 6SO3-2OH but almost none for 6CN-2OH. Isothermal calorimetry measurements showed that all three fluorophores form 1:1 inclusion complex with comparable binding constants (285, 420, and 580 M-1 for 2OH, 6SO3-2OH, and 6CN-2OH, respectively). Molecular dynamics simulation further revealed that binding modes are quite similar, and the distribution of water molecules around the proton-donating hydroxyl group of the photoacids are also comparable. Consequently, the difference in the fluorescence response should be accounted solely to the difference in the photoacidity strengths.
Collapse
Affiliation(s)
- Tousif Hossen
- Department of Chemistry , Indian Institute of Technology Guwahati , Guwahati 781039 , Assam , India
| | - Kalyanasis Sahu
- Department of Chemistry , Indian Institute of Technology Guwahati , Guwahati 781039 , Assam , India
| |
Collapse
|
14
|
Ekimova M, Hoffmann F, Bekçioğlu-Neff G, Rafferty A, Kornilov O, Nibbering ETJ, Sebastiani D. Ultrafast Proton Transport between a Hydroxy Acid and a Nitrogen Base along Solvent Bridges Governed by the Hydroxide/Methoxide Transfer Mechanism. J Am Chem Soc 2019; 141:14581-14592. [PMID: 31446754 PMCID: PMC8168916 DOI: 10.1021/jacs.9b03471] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Aqueous
proton transport plays a key role in acid–base neutralization
and energy transport through biological membranes and hydrogen fuel
cells. Extensive experimental and theoretical studies have resulted
in a highly detailed elucidation of one of the underlying microscopic
mechanisms for aqueous excess proton transport, known as the von Grotthuss
mechanism, involving different hydrated proton configurations with
associated high fluxional structural dynamics. Hydroxide transport,
with approximately 2-fold-lower bulk diffusion rates compared to those
of excess protons, has received much less attention. We present femtosecond
UV/IR pump–probe experiments and ab initio molecular dynamics
simulations of different proton transport pathways of bifunctional
photoacid 7-hydroxyquinoline (7HQ) in water/methanol mixtures. For
7HQ solvent-dependent photoacidity, free-energy–reactivity
correlation behavior and quantum mechanics/molecular mechanics (QM/MM)
trajectories point to a dominant OH–/CH3O– transport pathway for all water/methanol mixing
ratios investigated. Our joint ultrafast infrared spectroscopic and
ab initio molecular dynamics study provides conclusive evidence for
the hydrolysis/methanolysis acid–base neutralization pathway,
as formulated by Manfred Eigen half a century ago. Our findings on
the distinctly different acid–base reactivities for aromatic
hydroxyl and aromatic nitrogen functionalities suggest the usefulness
of further exploration of these free-energy–reactivity correlations
as a function of solvent polarity. Ultimately the determination of
solvent-dependent acidities will contribute to a better understanding
of proton-transport mechanisms at weakly polar surfaces and near polar
or ionic regions in transmembrane proton pump proteins or hydrogen
fuel cell materials.
Collapse
Affiliation(s)
- Maria Ekimova
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie , Max Born Str. 2A , 12489 Berlin , Germany
| | - Felix Hoffmann
- Institut für Chemie , Martin-Luther-Universität Halle-Wittenberg , Von-Danckelmann-Platz 4 , 06120 Halle , Saale , Germany
| | - Gül Bekçioğlu-Neff
- Institut für Chemie , Martin-Luther-Universität Halle-Wittenberg , Von-Danckelmann-Platz 4 , 06120 Halle , Saale , Germany
| | - Aidan Rafferty
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie , Max Born Str. 2A , 12489 Berlin , Germany
| | - Oleg Kornilov
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie , Max Born Str. 2A , 12489 Berlin , Germany
| | - Erik T J Nibbering
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie , Max Born Str. 2A , 12489 Berlin , Germany
| | - Daniel Sebastiani
- Institut für Chemie , Martin-Luther-Universität Halle-Wittenberg , Von-Danckelmann-Platz 4 , 06120 Halle , Saale , Germany
| |
Collapse
|
15
|
Demianets I, Hunt JR, Dawlaty JM, Williams TJ. Optical pKa Control in a Bifunctional Iridium Complex. Organometallics 2019. [DOI: 10.1021/acs.organomet.8b00778] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ivan Demianets
- Donald P. and Katherine B. Loker Hydrocarbon Institute and Department of Chemistry, University of Southern California, Los Angeles, California 90089-1661, United States
| | - Jonathan R. Hunt
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Jahan M. Dawlaty
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Travis J. Williams
- Donald P. and Katherine B. Loker Hydrocarbon Institute and Department of Chemistry, University of Southern California, Los Angeles, California 90089-1661, United States
| |
Collapse
|
16
|
Hunt JR, Tseng C, Dawlaty JM. Donor-acceptor preassociation, excited state solvation threshold, and optical energy cost as challenges in chemical applications of photobases. Faraday Discuss 2019; 216:252-268. [PMID: 31025987 DOI: 10.1039/c8fd00215k] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Photobases are molecules with increased pKa in the excited state that can serve to transduce light energy into proton removal capability. They can be used to control chemical reactions using light, such as removing protons from a catalytic site in reactions that are rate-limited by proton transfer. We identify and explore several major challenges toward their practical applications. Two important challenges are the need for pre-association (or ground state hydrogen bonding) between the proton donor and the photobase, and the need for excited state solvation of the photogenerated products. We investigate these two challenges with the photobase 5-methoxyquinoline as the proton acceptor and a low-pKa alcohol, 2,2,2-trifluoroethanol, as the proton donor. We vary the concentration of the donor in a background non-hydrogen-bonding solvent. Using absorption spectroscopy, we have identified that the donor-acceptor concentration ratio must exceed 100 : 1 to achieve appreciable ground state hydrogen bonding. Interestingly, emission spectroscopy reveals that the onset of ground state hydrogen bonding does not guarantee successful excited state proton transfer. It takes an additional order of magnitude increase in donor-acceptor ratio to achieve that goal, revealing that it is necessary to have excess donor molecules to reach the solvation threshold for the photogenerated products. The next challenge is reducing the large ground-excited state energy gap, which often requires UV photons to drive proton transfer. We show experimental and computational data comparing the photobasicity and optical energy gap for a few N-aromatic heterocyclic photobases. In general, we find that reducing the energy gap by increasing the conjugation size necessarily reduces photobasicity, while adding substituents of varying electron-withdrawing strength allows some fine-tuning of this effect. The combination of these two factors provide a preliminary design space for creating new photobasic molecules.
Collapse
Affiliation(s)
| | - Cindy Tseng
- University of Southern California, 920 Bloom Walk, Los Angeles, USA.
| | - Jahan M Dawlaty
- University of Southern California, 920 Bloom Walk, Los Angeles, USA.
| |
Collapse
|
17
|
Sheng W, Nairat M, Pawlaczyk PD, Mroczka E, Farris B, Pines E, Geiger JH, Borhan B, Dantus M. Ultrafast Dynamics of a “Super” Photobase. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201806787] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Wei Sheng
- Department of Chemistry Michigan State University E. Lansing MI 48824 USA
| | - Muath Nairat
- Department of Chemistry Michigan State University E. Lansing MI 48824 USA
| | | | - Elizabeth Mroczka
- Department of Chemistry Michigan State University E. Lansing MI 48824 USA
| | - Benjamin Farris
- Department of Chemistry Michigan State University E. Lansing MI 48824 USA
| | - Ehud Pines
- Department of Chemistry Ben-Gurion University of the Negev POB 653 Beer Sheva 84105 Israel
| | - James H. Geiger
- Department of Chemistry Michigan State University E. Lansing MI 48824 USA
| | - Babak Borhan
- Department of Chemistry Michigan State University E. Lansing MI 48824 USA
| | - Marcos Dantus
- Department of Chemistry Michigan State University E. Lansing MI 48824 USA
- Department of Physics and Astronomy Michigan State University East Lansing MI 48824 USA
| |
Collapse
|
18
|
Sheng W, Nairat M, Pawlaczyk PD, Mroczka E, Farris B, Pines E, Geiger JH, Borhan B, Dantus M. Ultrafast Dynamics of a "Super" Photobase. Angew Chem Int Ed Engl 2018; 57:14742-14746. [PMID: 30152115 DOI: 10.1002/anie.201806787] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 07/26/2018] [Indexed: 11/08/2022]
Abstract
Molecular reactivity can change dramatically with the absorption of a photon due to the difference of the electronic configurations between the excited and ground states. Here we report on the discovery of a modular system (Schiff base formed from an aldehyde and an amine) that upon photoexcitation yields a more basic imine capable of intermolecular proton transfer from protic solvents. Ultrafast dynamics of the excited state conjugated Schiff base reveals the pathway for proton transfer, culminating in a 14-unit increase in pKa to give the excited state pKa * >20 in ethanol.
Collapse
Affiliation(s)
- Wei Sheng
- Department of Chemistry, Michigan State University, E. Lansing, MI, 48824, USA
| | - Muath Nairat
- Department of Chemistry, Michigan State University, E. Lansing, MI, 48824, USA
| | - Patrick D Pawlaczyk
- Department of Chemistry, Michigan State University, E. Lansing, MI, 48824, USA
| | - Elizabeth Mroczka
- Department of Chemistry, Michigan State University, E. Lansing, MI, 48824, USA
| | - Benjamin Farris
- Department of Chemistry, Michigan State University, E. Lansing, MI, 48824, USA
| | - Ehud Pines
- Department of Chemistry, Ben-Gurion University of the Negev, POB 653, Beer Sheva, 84105, Israel
| | - James H Geiger
- Department of Chemistry, Michigan State University, E. Lansing, MI, 48824, USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, E. Lansing, MI, 48824, USA
| | - Marcos Dantus
- Department of Chemistry, Michigan State University, E. Lansing, MI, 48824, USA.,Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| |
Collapse
|
19
|
Hunt JR, Dawlaty JM. Photodriven Deprotonation of Alcohols by a Quinoline Photobase. J Phys Chem A 2018; 122:7931-7940. [DOI: 10.1021/acs.jpca.8b06152] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Jonathan Ryan Hunt
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Jahan M. Dawlaty
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| |
Collapse
|
20
|
Driscoll EW, Hunt JR, Dawlaty JM. Proton Capture Dynamics in Quinoline Photobases: Substituent Effect and Involvement of Triplet States. J Phys Chem A 2017; 121:7099-7107. [DOI: 10.1021/acs.jpca.7b04512] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Eric William Driscoll
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Jonathan Ryan Hunt
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Jahan M. Dawlaty
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| |
Collapse
|
21
|
Xiao H, Ma L, Fang W, Chen X. A pOH Jump Driven by N═N Out-of-Plane Motion in the Photoisomerization of Water-Solvated Triazabutadiene. J Phys Chem A 2017; 121:4939-4947. [DOI: 10.1021/acs.jpca.7b04817] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hongmei Xiao
- Key Laboratory of Theoretical
and Computational Photochemistry of Ministry of Education, Department
of Chemistry, Beijing Normal University, Xin-wai-da-jie No. 19, Beijing, 100875, Peoplés Republic of China
| | - Lishuang Ma
- Key Laboratory of Theoretical
and Computational Photochemistry of Ministry of Education, Department
of Chemistry, Beijing Normal University, Xin-wai-da-jie No. 19, Beijing, 100875, Peoplés Republic of China
| | - Weihai Fang
- Key Laboratory of Theoretical
and Computational Photochemistry of Ministry of Education, Department
of Chemistry, Beijing Normal University, Xin-wai-da-jie No. 19, Beijing, 100875, Peoplés Republic of China
| | - Xuebo Chen
- Key Laboratory of Theoretical
and Computational Photochemistry of Ministry of Education, Department
of Chemistry, Beijing Normal University, Xin-wai-da-jie No. 19, Beijing, 100875, Peoplés Republic of China
| |
Collapse
|
22
|
Singh AK, Ghosh S, Kancherla R, Datta A. Engineering the Excited-State Dynamics of 3-Aminoquinoline by Chemical Modification and Temperature Variation. J Phys Chem B 2016; 120:12920-12927. [DOI: 10.1021/acs.jpcb.6b09939] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Avinash Kumar Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Srijon Ghosh
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Rajesh Kancherla
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| |
Collapse
|
23
|
Hoffmann F, Ekimova M, Bekçioğlu-Neff G, Nibbering ETJ, Sebastiani D. Combined Experimental and Theoretical Study of the Transient IR Spectroscopy of 7-Hydroxyquinoline in the First Electronically Excited Singlet State. J Phys Chem A 2016; 120:9378-9389. [DOI: 10.1021/acs.jpca.6b07843] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Felix Hoffmann
- Institut
für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz
4, 06120 Halle (Saale), Germany
| | - Maria Ekimova
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Gül Bekçioğlu-Neff
- Institut
für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz
4, 06120 Halle (Saale), Germany
- Physics
Department, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Erik T. J. Nibbering
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A, 12489 Berlin, Germany
| | - Daniel Sebastiani
- Institut
für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz
4, 06120 Halle (Saale), Germany
| |
Collapse
|
24
|
Driscoll EW, Hunt JR, Dawlaty JM. Photobasicity in Quinolines: Origin and Tunability via the Substituents' Hammett Parameters. J Phys Chem Lett 2016; 7:2093-2099. [PMID: 27195691 DOI: 10.1021/acs.jpclett.6b00790] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
| | - Jonathan Ryan Hunt
- University of Southern California , Los Angeles, California 90089, United States
| | - Jahan M Dawlaty
- University of Southern California , Los Angeles, California 90089, United States
| |
Collapse
|
25
|
Pines D, Nibbering ETJ, Pines E. Monitoring the Microscopic Molecular Mechanisms of Proton Transfer in Acid-base Reactions in Aqueous Solutions. Isr J Chem 2015. [DOI: 10.1002/ijch.201500057] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
26
|
Spies C, Shomer S, Finkler B, Pines D, Pines E, Jung G, Huppert D. Solvent dependence of excited-state proton transfer from pyranine-derived photoacids. Phys Chem Chem Phys 2015; 16:9104-14. [PMID: 24700348 DOI: 10.1039/c3cp55292f] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Steady-state and time-resolved techniques were employed to study the excited-state proton-transfer (ESPT) rate of two newly synthesized 8-hydroxy-1,3,6-pyrenetrisulfonate (pyranine, HPTS) derived photoacids in three protic solvents, water, methanol and ethanol. The ESPT rate constant k(PT) of tris(1,1,1,3,3,3-hexafluoropropan-2-yl)-8-hydroxypyrene-1,3,6-trisulfonate, 1a, whose pK(a)* ~ -4, in water, methanol and ethanol is 3 × 10(11) s(-1), 8 × 10(9) s(-1) and 5 × 10(9) s(-1) respectively. (8-Hydroxy-N1,N3,N6-tris(2-hydroxyethyl)-N1,N3,N6-trimethylpyrene-1,3,6 trisulfonamide, 1b) is a weaker acid than 1a but still a strong photoacid with pK(a)* ~ -1 and the ESPT rate in water, methanol and ethanol is 7 × 10(10) s(-1), 4 × 10(8) s(-1) and 2 × 10(8) s(-1). We qualitatively explain our kinetic results by a Marcus-like free-energy correlation which was found to have a general form suitable for describing proton transfer reactions in both the proton-adiabatic and the proton-non-adiabatic limits.
Collapse
Affiliation(s)
- Christian Spies
- Biophysical Chemistry, Saarland University, Campus, Building B2 2, D-66123 Saarbrücken, Germany.
| | | | | | | | | | | | | |
Collapse
|
27
|
Prémont-Schwarz M, Barak T, Pines D, Nibbering ETJ, Pines E. Ultrafast Excited-State Proton-Transfer Reaction of 1-Naphthol-3,6-Disulfonate and Several 5-Substituted 1-Naphthol Derivatives. J Phys Chem B 2013; 117:4594-603. [DOI: 10.1021/jp308746x] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mirabelle Prémont-Schwarz
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Str. 2 A, D-12489 Berlin, Germany
| | - Tamar Barak
- Department of Chemistry, Ben-Gurion University of the Negev,
P.O.B. 653, Beer-Sheva 84105, Israel
| | - Dina Pines
- Department of Chemistry, Ben-Gurion University of the Negev,
P.O.B. 653, Beer-Sheva 84105, Israel
| | - Erik T. J. Nibbering
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Str. 2 A, D-12489 Berlin, Germany
| | - Ehud Pines
- Department of Chemistry, Ben-Gurion University of the Negev,
P.O.B. 653, Beer-Sheva 84105, Israel
| |
Collapse
|