1
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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.
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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
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2
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Szemik-Hojniak A, Deperasińska I, Erez Y, Gawłowska M, Jerzykiewicz L. Ultrafast excited state dynamics of pyridine N-oxide derivative in solution; femtosecond fluorescence up-conversion and theoretical calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 285:121896. [PMID: 36183536 DOI: 10.1016/j.saa.2022.121896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 08/29/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
In this study we have investigated 2-ethylamino-4-nitro-6-methyl pyridine N-oxide (2E6M) molecule that belongs to important group of Proton Coupled Electron Transfer (PCET) compounds where both the charge transfer (CT) and proton transfer processes in excited states may proceed. In this case, this is possible due to the donors and acceptors of electrons and protons in this system, as well as due to the presence of intramolecular {N-H… O [2,566(3) Å}, hydrogen bond.Using stationary and time-resolved spectroscopy, as well as quantum chemical calculations on the DFT and TD DFT B3LYP/6-31G (d,p) level of theory, a partial CT nature of the S0 → S1 transition in both tautomeric forms (N and T) has been revealed. Additionally, the excited state intramolecular proton transfer (ESIPT) process shown to be more favorable in apolar and weakly polar solvents than in strongly polar acetonitrile (EN(S1) > ET(S1). The displacement of charge from the amine group and the ring to the nitro group has been observed on the changing shapes of the HOMO and LUMO orbitals involved in this transition what further quantitatively allowed to realize the increase in the dipole moment of both forms in the electronic excited state. The calculations show that in two solvents with radically different polarity (heptane, acetonitrile), dipole moments of both forms are very similar [in acetonitrile uN(S1) and uT(S1) are 11.0 D and 11.5 D, respectively]. Hence, in polar media both forms can be stabilized in a comparable manner. This made it difficult for us to assign a single fluorescent band in acetonitrile to one of the tautomeric forms. However, it seems that due to application of time-resolved spectroscopy, this problem has been clarified. The TCSPC decay curve in acetonitrile with an ultrafast lifetime assigned to the (N) form, along with the femtosecond up-conversion signals that demonstrated only an ultrafast decay without any rise-time of a new excited (T) species, allowed us to conclude that in 2E6M in strongly polar solvent the ESIPT does not occur.The unique fluorescence band origins from the (N) form. In protic solvents, the significant kinetic isotopic effects have provided us with conclusive evidence for the presence of the solvent-assisted ESIPT process. Furthermore, it was noticed that the fluorescence lifetime in D2O (100-120 fs) estimated from the up-conversion signals is about 40 times shorter relative to methanol. This may suggest that the sine qua non for the ESIPT process in 2E6M in protic solvents is the formation of a complex with a solvent molecule in the hydrogen bridge between the proton donor and proton acceptor, respectively.
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Affiliation(s)
- Anna Szemik-Hojniak
- Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14 st, 50-383 Wrocław, Poland; The Angelus Silesius State University of Applied Sciences, Institute of Health, Zamkowa 4 str 58-300 Wałbrzych, Poland.
| | - Irena Deperasińska
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46,02-668 Warsaw, Poland
| | - Yuval Erez
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel
| | - Monika Gawłowska
- The Angelus Silesius State University of Applied Sciences, Institute of Health, Zamkowa 4 str 58-300 Wałbrzych, Poland
| | - L Jerzykiewicz
- Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14 st, 50-383 Wrocław, Poland
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3
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Nakashima K, Georgiev A, Yordanov D, Matsushima Y, Hirashima SI, Miura T, Antonov L. Solvent-Triggered Long-Range Proton Transport in 7-Hydroxyquinoline Using a Sulfonamide Transporter Group. J Org Chem 2022; 87:6794-6806. [PMID: 35512011 DOI: 10.1021/acs.joc.2c00494] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The ability of long-range proton transport by substitution of 7-hydroxyquinoline at the eighth position with sulfonamide and sulfonylhydrazone rotor units to act as a crane-arm has been studied. Different proton transport pathways triggered by different stimuli have been established depending on the structure of the crane-arms. Solvent-driven proton switching from OH to the quinoline nitrogen (Nquin) site, facilitated by a sulfonamide transporter group in polar protic and aprotic solvents, has been confirmed by optical (absorption and fluorescence) and NMR spectroscopies as well as by single-crystal X-ray structure analysis. Photoinduced long-range proton transport to the Nquin site upon 340 nm UV light irradiation has been estimated in sulfonylhydrazone, which is not sensitive to solvent-driven switching. Both compounds have exhibited acid-triggered switching by trifluoroacetic acid due to the formation of a stable six-membered intramolecular hydrogen bonding interaction between the protonated Nquin and crane-arm. The structures of acid-switched form were confirmed by NMR spectroscopy and single-crystal X-ray structure analysis. The behavior of the compounds suggests a big step forward in the advanced proton pump-switching architecture because they cover three distinct driving forces in the switching process: solvent, light, and acid.
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Affiliation(s)
- Kosuke Nakashima
- Department of Pharmaceutical Chemistry, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Anton Georgiev
- Department of Organic Chemistry, University of Chemical Technology and Metallurgy, 8 St. Kliment Ohridski Boulevard, 1756 Sofia, Bulgaria.,Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Boulevard, 1784 Sofia, Bulgaria.,Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bonchev Avenue, Building 109, 1113 Sofia, Bulgaria
| | - Dancho Yordanov
- Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Boulevard, 1784 Sofia, Bulgaria.,Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Avenue, Building 9, Sofia 1113, Bulgaria
| | - Yasuyuki Matsushima
- Department of Pharmaceutical Chemistry, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Shin-Ichi Hirashima
- Department of Pharmaceutical Chemistry, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Tsuyoshi Miura
- Department of Pharmaceutical Chemistry, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Liudmil Antonov
- Department of Organic Chemistry, University of Chemical Technology and Metallurgy, 8 St. Kliment Ohridski Boulevard, 1756 Sofia, Bulgaria.,Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Boulevard, 1784 Sofia, Bulgaria
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4
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Dobkowski J, Kijak M, Gawinkowski S, Karpiuk E, Pietrzak M, Sazanovich IV, Waluk J. Solving the Puzzle of Unusual Excited-State Proton Transfer in 2,5-Bis(6-methyl-2-benzoxazolyl)phenol. J Phys Chem A 2022; 126:1823-1836. [PMID: 35286097 PMCID: PMC8958588 DOI: 10.1021/acs.jpca.1c10030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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2,5-Bis(6-methyl-2-benzoxazolyl)phenol
(BMP) exhibits
an ultrafast excited-state intramolecular proton transfer (ESIPT)
when isolated in supersonic jets, whereas in condensed phases the
phototautomerization is orders of magnitude slower. This unusual situation
leads to nontypical photophysical characteristics: dual fluorescence
is observed for BMP in solution, whereas only a single
emission, originating from the phototautomer, is detected for the
ultracold isolated molecules. In order to understand the completely
different behavior in the two regimes, detailed photophysical studies
have been carried out. Kinetic and thermodynamic parameters of ESIPT
were determined from stationary and transient picosecond absorption
and emission for BMP in different solvents in a broad
temperature range. These studies were combined with time-dependent-
density functional theory quantum-chemical modeling. The excited-state
double-well potential for BMP and its methyl-free analogue
were calculated by applying different hybrid functionals and compared
with the results obtained for another proton-transferring molecule,
2,5-bis(5-ethyl-2-benzoxazolyl)hydroquinone (DE-BBHQ).
The results lead to the model that explains the difference in proton-transfer
properties of BMP in vacuum and in the condensed phase
by inversion of the two lowest singlet states occurring along the
PT coordinate.
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Affiliation(s)
- Jacek Dobkowski
- Institute of Physical Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Michał Kijak
- Institute of Physical Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Sylwester Gawinkowski
- Institute of Physical Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Elena Karpiuk
- Institute of Physical Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Mariusz Pietrzak
- Institute of Physical Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Igor V Sazanovich
- Institute of Physical Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Jacek Waluk
- Institute of Physical Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw, Poland.,Faculty of Mathematics and Science, Cardinal Stefan Wyszyński University, Dewajtis 5, 01-815 Warsaw, Poland
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5
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Kaiser C, Halbritter T, Heckel A, Wachtveitl J. Proton-Transfer Dynamics of Photoacidic Merocyanines in Aqueous Solution. Chemistry 2021; 27:9160-9173. [PMID: 33929051 PMCID: PMC8361770 DOI: 10.1002/chem.202100168] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Indexed: 01/22/2023]
Abstract
Photoacids attract increasing scientific attention, as they are valuable tools to spatiotemporally control proton-release reactions and pH values of solutions. We present the first time-resolved spectroscopic study of the excited state and proton-release dynamics of prominent merocyanine representatives. Femtosecond transient absorption measurements of a pyridine merocyanine with two distinct protonation sites revealed dissimilar proton-release mechanisms: one site acts as a photoacid generator as its pKa value is modulated in the ground state after photoisomerization, while the other functions as an excited state photoacid which releases its proton within 1.1 ps. With a pKa drop of 8.7 units to -5.5 upon excitation, the latter phenolic site is regarded a super-photoacid. The 6-nitro derivative exhibits only a phenolic site with similar, yet slightly less photoacidic characteristics and both compounds transfer their proton to methanol and ethanol. In contrast, for the related 6,8-dinitro compound an intramolecular proton transfer to the ortho-nitro group is suggested that is involved in a rapid relaxation into the ground state.
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Affiliation(s)
- Christoph Kaiser
- Institute for Physical and Theoretical ChemistryGoethe University Frankfurt/MainMax-von-Laue-Str. 760438Frankfurt/MainGermany
| | - Thomas Halbritter
- Current address: Department of Chemistry, Science InstituteUniversity of IcelandDunhaga 3Reykjavikpostcode is missingIceland
- Institute for Organic Chemistry and Chemical BiologyGoethe University Frankfurt/MainMax-von-Laue-Str. 760438Frankfurt/MainGermany
| | - Alexander Heckel
- Institute for Organic Chemistry and Chemical BiologyGoethe University Frankfurt/MainMax-von-Laue-Str. 760438Frankfurt/MainGermany
| | - Josef Wachtveitl
- Institute for Physical and Theoretical ChemistryGoethe University Frankfurt/MainMax-von-Laue-Str. 760438Frankfurt/MainGermany
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6
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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.
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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
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7
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Lahiri J, Moemeni M, Kline J, Magoulas I, Yuwono SH, Laboe M, Shen J, Borhan B, Piecuch P, Jackson JE, Blanchard GJ, Dantus M. Isoenergetic two-photon excitation enhances solvent-to-solute excited-state proton transfer. J Chem Phys 2020; 153:224301. [PMID: 33317305 PMCID: PMC7725536 DOI: 10.1063/5.0020282] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 11/15/2020] [Indexed: 01/05/2023] Open
Abstract
Two-photon excitation (TPE) is an attractive means for controlling chemistry in both space and time. Since isoenergetic one- and two-photon excitations (OPE and TPE) in non-centrosymmetric molecules are allowed to reach the same excited state, it is usually assumed that they produce similar excited-state reactivity. We compare the solvent-to-solute excited-state proton transfer of the super photobase FR0-SB following isoenergetic OPE and TPE. We find up to 62% increased reactivity following TPE compared to OPE. From steady-state spectroscopy, we rule out the involvement of different excited states and find that OPE and TPE spectra are identical in non-polar solvents but not in polar ones. We propose that differences in the matrix elements that contribute to the two-photon absorption cross sections lead to the observed enhanced isoenergetic reactivity, consistent with the predictions of our high-level coupled-cluster-based computational protocol. We find that polar solvent configurations favor greater dipole moment change between ground and excited states, which enters the probability for TPE as the absolute value squared. This, in turn, causes a difference in the Franck-Condon region reached via TPE compared to OPE. We conclude that a new method has been found for controlling chemical reactivity via the matrix elements that affect two-photon cross sections, which may be of great utility for spatial and temporal precision chemistry.
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Affiliation(s)
- Jurick Lahiri
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - Mehdi Moemeni
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - Jessica Kline
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - Ilias Magoulas
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - Stephen H. Yuwono
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - Maryann Laboe
- Department of Chemical Engineering and Material Science, Michigan State University, East Lansing, Michigan 48824, USA
| | - Jun Shen
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - Piotr Piecuch
- Authors to whom correspondence should be addressed: , Tel.: +1-517-353-0501; , Tel.: +1-517-353-1151; , Tel.: +1-517-353-0504; , Tel.: +1-517-353-1105; and , Tel.: +1-517-353-1191
| | - James E. Jackson
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - G. J. Blanchard
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
| | - Marcos Dantus
- Authors to whom correspondence should be addressed: , Tel.: +1-517-353-0501; , Tel.: +1-517-353-1151; , Tel.: +1-517-353-0504; , Tel.: +1-517-353-1105; and , Tel.: +1-517-353-1191
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8
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Georgiev A, Antonov L. 8-(Pyridin-2-yl)quinolin-7-ol as a Platform for Conjugated Proton Cranes: A DFT Structural Design. MICROMACHINES 2020; 11:mi11100901. [PMID: 33003325 PMCID: PMC7601234 DOI: 10.3390/mi11100901] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 09/23/2020] [Accepted: 09/29/2020] [Indexed: 12/15/2022]
Abstract
Theoretical design of conjugated proton cranes, based on 7-hydroxyquinoline as a tautomeric sub-unit, has been attempted by using ground and excited state density functional theory (DFT) calculations in various environments. The proton crane action request existence of a single enol tautomer in ground state, which under excitation goes to the excited keto tautomer through a series of consecutive excited-state intramolecular proton transfer (ESIPT) steps with the participation of the crane sub-unit. A series of substituted pyridines was used as crane sub-units and the corresponding donor-acceptor interactions were evaluated. The results suggest that the introduction of strong electron donor substituents in the pyridine ring creates optimal conditions for 8-(pyridin-2-yl)quinolin-7-ols to act as proton cranes.
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Affiliation(s)
- Anton Georgiev
- Department of Organic Chemistry, University of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria;
- Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Liudmil Antonov
- Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
- Correspondence:
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9
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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.
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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
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10
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Ekimova M, Hoffmann F, Bekcioglu-Neff G, Rafferty A, Nibbering ETJ, Sebastiani D. Ultrafast proton transport in water-methanol mixtures. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201920509004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Femtosecond UV/IR pump-probe experiments and ab initio molecular dynamics simulations of 7-hydroxyquinoline in water-methanol mixtures demonstrate an unexpectedly dominant OH-/CH3O- transport pathway but consistent with a solvent-dependent photoacidity free energy-reactivity correlation behaviour.
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11
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Kumpulainen T, Qian J, Brouwer AM. Spectroscopic Study of a Cinchona Alkaloid-Catalyzed Henry Reaction. ACS OMEGA 2018; 3:1871-1880. [PMID: 29503974 PMCID: PMC5830691 DOI: 10.1021/acsomega.7b01713] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 01/05/2018] [Indexed: 06/08/2023]
Abstract
A spectroscopic study of an organocatalytic Henry reaction between nitroalkanes and aldehydes catalyzed by a quinidine-derived Cinchona alkaloid is described. The binding modes of the reaction substrates are investigated using electronic absorption and fluorescence spectroscopy and further corroborated by nuclear magnetic resonance measurements. Aldehydes are shown to associate with both the 6'-OH group and the basic quinuclidine nitrogen of the catalyst, whereas nitroalkanes do not exhibit a clear binding mode. Reaction progress kinetic analysis reveals that the reaction is first-order in both of the substrates and the catalyst. Second, the reaction proceeds approximately five times faster in the excess of the nitroalkanes than in the excess of the aldehydes, suggesting that binding of the aldehydes results in the inhibition of the catalyst. Aldehydes deactivate the basic quinuclidine site, thus suppressing the deprotonation of the nitroalkanes which is the proposed initial step in the reaction cycle.
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Affiliation(s)
| | | | - Albert M. Brouwer
- Van’t Hoff Institute for Molecular
Sciences, Faculty of Science, University
of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands
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12
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Gil M, Kijak M, Piwoński H, Herbich J, Waluk J. Non-typical fluorescence studies of excited and ground state proton and hydrogen transfer. Methods Appl Fluoresc 2017; 5:014007. [PMID: 28248649 DOI: 10.1088/2050-6120/aa5e29] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Fluorescence studies of tautomerization have been carried out for various systems that exhibit single and double proton or hydrogen translocation in various environments, such as liquid and solid condensed phases, ultracold supersonic jets, and finally, polymer matrices with single emitters. We focus on less explored areas of application of fluorescence for tautomerization studies, using porphycene, a porphyrin isomer, as an example. Fluorescence anisotropy techniques allow investigations of self-exchange reactions, where the reactant and product are formally identical. Excitation with polarized light makes it possible to monitor tautomerization in single molecules and to detect their three-dimensional orientation. Analysis of fluorescence from single vibronic levels of jet-isolated porphycene not only demonstrates coherent tunneling of two internal protons, but also indicates that the process is vibrational mode-specific. Next, we present bifunctional proton donor-acceptor systems, molecules that are able, depending on the environment, to undergo excited state single intramolecular or double intermolecular proton transfer. For molecules that have donor and acceptor groups located in separate moieties linked by a single bond, excited state tautomerization can be coupled to mutual twisting of the two subunits.
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Affiliation(s)
- Michał Gil
- Institute of Physical Chemistry Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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13
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Kumpulainen T, Lang B, Rosspeintner A, Vauthey E. Ultrafast Elementary Photochemical Processes of Organic Molecules in Liquid Solution. Chem Rev 2016; 117:10826-10939. [DOI: 10.1021/acs.chemrev.6b00491] [Citation(s) in RCA: 249] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Tatu Kumpulainen
- Department of Physical Chemistry,
Sciences II, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | - Bernhard Lang
- Department of Physical Chemistry,
Sciences II, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | - Arnulf Rosspeintner
- Department of Physical Chemistry,
Sciences II, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | - Eric Vauthey
- Department of Physical Chemistry,
Sciences II, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
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14
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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
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15
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Park SY, Ghosh P, Park SO, Lee YM, Kwak SK, Kwon OH. Origin of ultraweak fluorescence of 8-hydroxyquinoline in water: photoinduced ultrafast proton transfer. RSC Adv 2016. [DOI: 10.1039/c5ra23802a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Ultrafast excited-state proton transfer of 8-hydroxuquinoline to produce short-lived its tautomeric form causes immensely attenuated fluorescence in water.
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Affiliation(s)
- Sun-Young Park
- Center for Soft and Living Matter
- Institute for Basic Science (IBS)
- Ulsan 689-798
- Republic of Korea
| | - Prasun Ghosh
- Department of Chemistry
- Ulsan National Institute of Science and Technology (UNIST)
- Ulsan 689-798
- Republic of Korea
| | - Sung O. Park
- School of Energy and Chemical Engineering
- Ulsan National Institute of Science and Technology (UNIST)
- Ulsan 689-798
- Republic of Korea
| | - Young Min Lee
- Department of Chemistry
- Ulsan National Institute of Science and Technology (UNIST)
- Ulsan 689-798
- Republic of Korea
| | - Sang Kyu Kwak
- School of Energy and Chemical Engineering
- Ulsan National Institute of Science and Technology (UNIST)
- Ulsan 689-798
- Republic of Korea
| | - Oh-Hoon Kwon
- Center for Soft and Living Matter
- Institute for Basic Science (IBS)
- Ulsan 689-798
- Republic of Korea
- Department of Chemistry
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16
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Carnerero JM, González-Benjumea A, Carmona C, Balón M. Spectroscopic study of the ground and excited state prototropic equilibria of 4-azaindole. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2012; 97:1072-1078. [PMID: 22925984 DOI: 10.1016/j.saa.2012.07.099] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 07/23/2012] [Accepted: 07/26/2012] [Indexed: 06/01/2023]
Abstract
The ground and singlet excited state prototropism of 4-azaindole, 4AI, in acid and basic aqueous solutions, inside and outside the pH range, has been systematically studied by using absorption and fluorescence spectroscopic techniques. These studies have thrown light on some interesting aspects on the nature and the photophysics of the 4-AI prototropic species. Thus, the changes of the 4AI absorption spectra reveal the existence of four ground state species; the pyridinic protonated cation, C (pK(a)(C)=7.5±0.1), the neutral molecule, N (pK(a)(N)=15.5±0.5), the pyrrolic deprotonated anion, A, and a previously unnoticed dication, DC (pK(a)(DC)=-4.6±0.4). Besides the emissions of these species, a new fluorescence profile appears in alkaline solutions at around 500nm. This extra band has been ascribed to the neutral phototautomer, NT. What is more relevant to this study is the fact that the position and the intensity of the emission band assigned to the monoprotonated cation are very different from those observed for the normal cation of the 7-azaindole, 7-AI. This together with the fact that for the formation of the DC species a cationic precursor with a quinoid structure must be invoked, have prompted us to assign this cationic emission to the isomeric CI cations. Finally, the excited-state pK(a)s of the prototropic species of 4AI have been theoretically estimated by using the Förster-Weller cycle.
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Affiliation(s)
- José M Carnerero
- Departamento de Química Física, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain
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17
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Piechowska J, Huttunen K, Wróbel Z, Lemmetyinen H, Tkachenko NV, Gryko DT. Excited state intramolecular proton transfer in electron-rich and electron-poor derivatives of 10-hydroxybenzo[h]quinoline. J Phys Chem A 2012; 116:9614-20. [PMID: 22946783 DOI: 10.1021/jp305459r] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Eight previously inaccessible derivatives of 10-hydroxybenzo[h]quinoline were prepared via a straightforward strategy comprising formation of the benzo[h]quinoline skeleton followed by C-H acetoxylation at position 10. The occurrence of excited state intramolecular proton transfer (ESIPT) was detected in all cases since emission was observed only from the excited keto-tautomer. Studies on derivatives bearing both electron-donating and electron-withdrawing groups adjacent to the pyridine ring allowed us to identify some design patterns giving rise to NIR emission and large Stokes shifts. For a derivative of 10-hydroxybenzo[c]acridine, emission at 745 nm was observed, one of the lowest energy fluorescence ever reported for ESIPT system. On the basis of time-resolved measurements, proton transfer was found to be extremely fast with time constants in the range (0.08-0.45 ps).
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Affiliation(s)
- Joanna Piechowska
- Institute of Chemistry of the Polish Academy of Sciences, Warsaw, Poland
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18
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Kwon OH, Mohammed OF. Water-wire catalysis in photoinduced acid–base reactions. Phys Chem Chem Phys 2012; 14:8974-80. [DOI: 10.1039/c2cp23796b] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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19
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Piechowska J, Gryko DT. Preparation of a family of 10-hydroxybenzo[h]quinoline analogues via a modified Sanford reaction and their excited state intramolecular proton transfer properties. J Org Chem 2011; 76:10220-8. [PMID: 22066857 DOI: 10.1021/jo202072d] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We have developed a highly optimized methodology that allows for the oxidative acetoxylation of a sterically and electronically demanding library of analogues of benzo[h]quinoline. The optimal conditions for the insertion of an OAc group were identified after examining various reaction parameters (solvent, oxidant, catalyst, temperature, time). The conditions identified (Pd(OAc)(2), PhI(OAc)(2), MeCN, 150 °C, 16 h), combined with the hydrolysis of acetates, resulted in the formation of hydroxybenzoquinolines in 27-59% yield, whereas all previously published procedures were ineffective. This synthesis was compatible with diverse functionalities (ester, aldehyde, carbon-carbon triple bond) and, most importantly, worked for sterically hindered analogues as well as for compounds possessing electron-donating and electron-withdrawing substituents at various positions. All the obtained compounds demonstrated excited-state intramolecular proton transfer (ESIPT) manifesting as small fluorescence quantum yields and large Stokes shifts (8300-9660 cm(-1)). The effect of structural variations in eight 10-hydroxybenzo[h]quinoline analogues on absorption and emission properties was studied in detail.
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Affiliation(s)
- Joanna Piechowska
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
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20
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McGrier PL, Solntsev KM, Zucchero AJ, Miranda OR, Rotello VM, Tolbert LM, Bunz UHF. Hydroxydialkylamino Cruciforms: Amphoteric Materials with Unique Photophysical Properties. Chemistry 2011; 17:3112-9. [DOI: 10.1002/chem.201002865] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Indexed: 11/08/2022]
Affiliation(s)
- Psaras L. McGrier
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332 (USA)
| | - Kyril M. Solntsev
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332 (USA)
| | - Anthony J. Zucchero
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332 (USA)
| | - Oscar R. Miranda
- Department of Chemistry, 710 North Pleasant St., University of Massachusetts Amherst, MA 01003 (USA)
| | - Vincent M. Rotello
- Department of Chemistry, 710 North Pleasant St., University of Massachusetts Amherst, MA 01003 (USA)
| | - Laren M. Tolbert
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332 (USA)
| | - Uwe H. F. Bunz
- Organisch‐Chemisches Institut, Ruprecht‐Karls‐Universität, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany), Fax: (+49) 6221548404
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332 (USA)
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21
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Erez Y, Huppert D. Excited-state intermolecular proton transfer of the firefly's chromophore D-luciferin. J Phys Chem A 2010; 114:8075-82. [PMID: 20684579 DOI: 10.1021/jp103264y] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Steady-state absorption and emission as well as time-resolved emission spectroscopies were employed to study the photophysics and photochemistry of D-luciferin, the firefly active bioluminescent compound. In aqueous solution the electronically excited-state protonated D-luciferin compound undergoes an efficient process of proton transfer to the solvent, with a rate constant k(PT) = 3.0 x 10(10) s(-1). We found a kinetic isotope effect of about 2.5 for this process. The deprotonated form of D-luciferin in the excited state recombines irreversibly with the geminate proton. Hence, the fluorescence decay of the deprotonated form is nonexponential, and the fluorescence quantum yield is low.
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Affiliation(s)
- Yuval Erez
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel
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22
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Competition between proton and H-atom transfer: The role of the chromophore environment in the green fluorescent protein. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.06.087] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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23
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24
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Zhu Y, Pavlos CM, Toscano JP, Dore TM. 8-Bromo-7-hydroxyquinoline as a Photoremovable Protecting Group for Physiological Use: Mechanism and Scope. J Am Chem Soc 2006; 128:4267-76. [PMID: 16569001 DOI: 10.1021/ja0555320] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two-photon excitation (2PE) of "caged" biomolecules represents a powerful method to investigate the temporal and spatial relevance of physiological function in real time and on living tissue, because the excitation volume can be restricted to 1 fL. Additionally, low-energy IR light is used, which minimizes tissue destruction and enables deeper penetration into tissue preparations. Exploitation of this technology for studying cell physiology requires the further development of photoremovable protecting groups with sufficient sensitivity to 2PE for use in "caged" compounds. 8-Bromo-7-hydroxyquinoline (BHQ) is efficiently photolyzed by classic 1PE (365 nm) and 2PE (740 nm) under simulated physiological conditions (aqueous buffer of high ionic strength, pH 7.2) to release carboxylates, phosphates, and diols-functional groups commonly found on bioactive molecules such as neurotransmitters, nucleic acids, and drugs. It is stable in the dark, soluble in water, and exhibits low levels of fluorescence, which will enable use in conjunction with fluorescent indicators of biological function. BHQ-protected effectors are synthetically accessible. Stern-Volmer quenching, time-resolved infrared (TRIR), and (18)O-labeling experiments suggest that the photolysis occurs through a solvent-assisted photoheterolysis (S(N)1) reaction mechanism on the sub-microsecond time scale. BHQ has the requisite photochemical and photophysical properties as a photoremovable protecting group to regulate the action of biological effectors in cell and tissue culture with light, especially 2PE.
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Affiliation(s)
- Yue Zhu
- Department of Chemistry, University of Georgia, Athens, 30602-2556, USA
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25
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Wang SL, Yeh TW, Ho TI. Photophysics and excited-state proton transfer of 2′-hydroxy-2-trans-styrylquinoline. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2005.11.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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26
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Kwon OH, Lee YS, Yoo BK, Jang DJ. Excited-State Triple Proton Transfer of 7-Hydroxyquinoline along a Hydrogen-Bonded Alcohol Chain: Vibrationally Assisted Proton Tunneling. Angew Chem Int Ed Engl 2006; 45:415-9. [PMID: 16323238 DOI: 10.1002/anie.200503209] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Oh-Hoon Kwon
- School of Chemistry, Seoul National University, NS60, Seoul 151-742, Korea
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27
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Kwon OH, Lee YS, Yoo BK, Jang DJ. Excited-State Triple Proton Transfer of 7-Hydroxyquinoline along a Hydrogen-Bonded Alcohol Chain: Vibrationally Assisted Proton Tunneling. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200503209] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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28
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Leiderman P, Huppert D, Agmon N. Transition in the temperature-dependence of GFP fluorescence: from proton wires to proton exit. Biophys J 2005; 90:1009-18. [PMID: 16284263 PMCID: PMC1367087 DOI: 10.1529/biophysj.105.069393] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In green fluorescent protein, photo-excitation leads to excited-state proton transfer from its chromophore, leaving behind a strongly fluorescing anion, while the proton is commonly thought to migrate internally to Glu-222. X-ray data show that the protein contains more extended hydrogen-bonded networks that can support proton migration (i.e., proton wires). Here we study the temperature-dependence of the transient fluorescence from both the acid and anionic forms up to 15 ns. At low temperatures, we find that the (lifetime-corrected) fluorescence of the acidic form decays asymptotically as t(-1/2), following quantitatively the solution of a one-dimensional diffusion equation for reversible geminate recombination with quenching. This indicates proton migration along the internal proton wires. A small degree of geminate proton quenching is attributed to the formation of the zwitterion by proton migration on a side-branch of the proton wire. Above 230 K, the fluorescence kinetics undergo a transition, exhibiting an asymptotic t(-3/2) decay, and the quenching effect disappears. We interpret these findings as evidence for a conformational change enabling the rotation of Thr-203, which eventually allows the proton to escape to the exterior solution.
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Affiliation(s)
- Pavel Leiderman
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel-Aviv University, Tel-Aviv, Israel
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29
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Mulon JB, Destandau E, Alain V, Bardez E. How can aluminium(III) generate fluorescence? J Inorg Biochem 2005; 99:1749-55. [PMID: 16055192 DOI: 10.1016/j.jinorgbio.2005.06.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 06/02/2005] [Accepted: 06/09/2005] [Indexed: 11/24/2022]
Abstract
In a previous paper [F. Launay, V. Alain, E. Destandau, N. Ramos, E. Bardez, P. Baret, J. L. Pierre, New J. Chem. 25 (2001) 1269-1280] [New J. Chem. 25 (2001) 1269], we showed that the hexadentate tripodal ligand O-TRENSOX (O-TR), incorporating three 8-hydroxy-5-sulfoquinoline subunits, was an efficient chelator of Al(III), quantitatively giving the 1:1 chelate in stoichiometric conditions even at the 10(-5) mol L(-1) concentration scale. However, the 1:1 Al:O-TR chelate turned out to be not significantly more fluorescent than the free ligand, whereas fluorescence enhancement by factors of at least 100 occurred either with the 3:1 Al:O-TR chelate, or with the 1:1 complex obtained with n-BUSOX, a ligand similar to one arm of O-TRENSOX. The present paper addresses the unresolved question of the magnitude of the fluorescence enhancement. Time-resolved fluorescence measurements, and additional complexation experiments carried out with the tripod TRENSOXCAMS2 (one 8-HQS and two 5-sulfocatechol subunits) and with n-BUCAMS analogous to one catechol arm of TRENSOXCAMS2, show that stoichiometry between Al(III) and the bound bidentate subunits is the key factor of fluorescence enhancement. The charge density on Al(III), tuned by the number of chelating groups and by their formal charges, influences the photoinduced charge transfer which tends to quench the fluorescence emission of the 8-hydroxyquinoline ligand. Transposition can be done to other bifunctional amphoterous ligands such as morin.
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Affiliation(s)
- Jean-Baptiste Mulon
- Laboratoire PPSM, Ecole Normale Supérieure de Cachan, 61 avenue du président Wilson, 94235 Cachan Cedex, France
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30
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Manca† C, Tanner C, Leutwyler S. Excited state hydrogen atom transfer in ammonia-wire and water-wire clusters. INT REV PHYS CHEM 2005. [DOI: 10.1080/01442350500390912] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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31
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Tanner C, Manca C, Leutwyler S. Exploring excited-state hydrogen atom transfer along an ammonia wire cluster: Competitive reaction paths and vibrational mode selectivity. J Chem Phys 2005; 122:204326. [PMID: 15945743 DOI: 10.1063/1.1924410] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The excited-state hydrogen-atom transfer (ESHAT) reaction of the 7-hydroxyquinoline(NH(3))(3) cluster involves a crossing from the initially excited (1)pipi(*) to a (1)pisigma(*) state. The nonadiabatic coupling between these states induces homolytic dissociation of the O-H bond and H-atom transfer to the closest NH(3) molecule, forming a biradical structure denoted HT1, followed by two more Grotthus-type translocation steps along the ammonia wire. We investigate this reaction at the configuration interaction singles level, using a basis set with diffuse orbitals. Intrinsic reaction coordinate calculations of the enol-->HT1 step predict that the H-atom transfer is preceded and followed by extensive twisting and bending of the ammonia wire, as well as large O-H...NH(3) hydrogen bond contraction and expansion. The calculations also predict an excited-state proton transfer path involving synchronous proton motions; however, it lies 20-25 kcal/mol above the ESHAT path. Higher singlet and triplet potential curves are calculated along the ESHAT reaction coordinate: Two singlet-triplet curve crossings occur within the HT1 product well and intersystem crossing to these T(n) states branches the reaction back to the enol reactant side, decreasing the ESHAT yield. In fact, a product yield of approximately 40% 7-ketoquinoline.(NH(3))(3) is experimentally observed. The vibrational mode selectivity of the enol-->HT1 reaction step [C. Manca, C. Tanner, S. Coussan, A. Bach, and S. Leutwyler, J. Chem. Phys. 121, 2578 (2004)] is shown to be due to the large sensitivity of the diffuse pisigma(*) state to vibrational displacements along the intermolecular coordinates.
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Affiliation(s)
- Christian Tanner
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3000 Bern 9, Switzerland
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32
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Solntsev KM, Clower CE, Tolbert LM, Huppert D. 6-Hydroxyquinoline-N-oxides: A New Class of “Super” Photoacids1. J Am Chem Soc 2005; 127:8534-44. [PMID: 15941289 DOI: 10.1021/ja0514545] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N-Oxidation of hydroxyquinolines leads to a dramatic increase in their excited-state acidity. Time-resolved and steady-state emission characterization of 6-hydroxyquinoline-N-oxide and 2-methyl-6-hydroxyquinoline-N-oxide reveals a rich but less complex proton-transfer behavior than that of its parent hydroxyquinoline. The electronic effect of the oxidized heterocyclic nitrogen atom makes the excited state both less basic and more acidic than the parent and adds hydroxyquinoline N-oxides to the class of high-acidity excited-state proton donors in photochemistry and photobiology. Adiabatic photoinduced proton transfer is accompanied by the efficient nonreversible deoxygenation and 1-2 oxygen migration.
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Affiliation(s)
- Kyril M Solntsev
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA.
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33
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Park HJ, Kwon OH, Ah CS, Jang DJ. Excited-State Tautomerization Dynamics of 7-Hydroxyquinoline in β-Cyclodextrin. J Phys Chem B 2005; 109:3938-43. [PMID: 16851447 DOI: 10.1021/jp046817m] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The excited-state tautomerization dynamics of 7-hydroxyquinoline encapsulated in beta-cyclodextrin is compared with that in pure water by measuring isotope-dependent fluorescence kinetics as well as absorption and emission spectra. The normal species tautomerizes stepwise via forming anionic intermediate species in both systems. However, the enol-deprotonation time (40 ps in water) becomes as large as 170 ps whereas the imine-protonation time of the anionic intermediate (160 ps in water) becomes as short as 85 ps in beta-cyclodextrin. The slow formation and the fast decay of the anionic species are attributed to the unstability of the charged species in hydrophobic cages. Encapsulation can be utilized to enhance fluorescence enormously and to accelerate selective reactions by retarding other processes.
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Affiliation(s)
- Han Jung Park
- School of Chemistry, Seoul National University, NS60, Seoul 151-742, Korea
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34
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Penedo JC, Lustres JLP, Lema IG, Rodríguez MCR, Mosquera M, Rodríguez-Prieto F. Solvent-Dependent Ground- and Excited-State Tautomerism in 2-(6‘-Hydroxy-2‘-pyridyl)benzimidazole. J Phys Chem A 2004. [DOI: 10.1021/jp049056w] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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35
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Yu H, Kwon OH, Jang DJ. Migration of Protons during the Excited-State Tautomerization of Aqueous 3-Hydroxyquinoline. J Phys Chem A 2004. [DOI: 10.1021/jp031293w] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hyunung Yu
- School of Chemistry, Seoul National University, NS60, Seoul 151-742, Korea
| | - Oh-Hoon Kwon
- School of Chemistry, Seoul National University, NS60, Seoul 151-742, Korea
| | - Du-Jeon Jang
- School of Chemistry, Seoul National University, NS60, Seoul 151-742, Korea
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36
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Scharnagl C, Raupp-Kossmann RA. Solution pKa Values of the Green Fluorescent Protein Chromophore from Hybrid Quantum-Classical Calculations. J Phys Chem B 2003. [DOI: 10.1021/jp036411u] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christina Scharnagl
- Physik-Department, E14 Lehrstuhl für Physik Weihenstephan, Technische Universität München, D-85350 Freising, Germany, and Institut für Theoretische Physik T38, Technische Universität München, D-85747 Garching, Germany
| | - Robert A. Raupp-Kossmann
- Physik-Department, E14 Lehrstuhl für Physik Weihenstephan, Technische Universität München, D-85350 Freising, Germany, and Institut für Theoretische Physik T38, Technische Universität München, D-85747 Garching, Germany
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37
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Tanner C, Manca C, Leutwyler S. Probing the Threshold to H Atom Transfer Along a Hydrogen-Bonded Ammonia Wire. Science 2003; 302:1736-9. [PMID: 14657491 DOI: 10.1126/science.1091708] [Citation(s) in RCA: 242] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We characterized the entrance channel, reaction threshold, and mechanism of an excited-state H atom transfer reaction along a unidirectionally hydrogen-bonded "wire" -O-H...NH3...NH3...NH3...N. Excitation of supersonically cooled 7-hydroxyquinoline.(NH3)3 to its vibrationless S1 state produces no reaction, whereas excitation of ammonia-wire vibrations induces H atom transfer with a reaction threshold approximately 200 wave numbers. Further translocation steps along the wire produce the S1 state 7-ketoquinoline.(NH3)3 tautomer. Ab initio calculations show that proton and electron movement along the wire are closely coupled. The rate-controlling S1 state barriers arise from crossings of a pipi* with a Rydberg-type pisigma* state.
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Affiliation(s)
- Christian Tanner
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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38
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Abstract
Ground and excited state processes induced by hydrogen bond formation are discussed for a family of heterocyclic compounds which possess both a proton donor (pyrrole NH group) and an acceptor (pyridine-type nitrogen). Excited state double proton transfer and rapid S(0) <-- S(1) internal conversion are observed only for molecules capable of forming cyclic, multiply hydrogen-bonded complexes. If the 1:1 cyclic, doubly hydrogen-bonded solvate is present in the ground state, the phototautomerization occurs even in rigid solvents at low temperatures. Internal conversion process requires solvent rearrangement and, therefore, does not proceed in a rigid environment. Another type of fluorescence quenching was also detected, involving photoinduced electron transfer from an excited chromophore to an aromatic hydrogen-bonded acceptor, such as pyridine. In molecules consisting of proton donor and acceptor units linked by a single bond, syn-anti rotamerization caused by hydrogen bonding is observed.
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Affiliation(s)
- Jacek Waluk
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44, 01-224 Warsaw, Poland.
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39
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Bach A, Tanner C, Manca C, Frey HM, Leutwyler S. Ground- and excited state proton transfer and tautomerization in 7-hydroxyquinoline⋅(NH3)n clusters: Spectroscopic and time resolved investigations. J Chem Phys 2003. [DOI: 10.1063/1.1603740] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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40
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Coussan S, Manca C, Tanner C, Bach A, Leutwyler S. Ammonia-chain clusters: Vibronic spectra of 7-hydroxyquinoline⋅(NH3)2. J Chem Phys 2003. [DOI: 10.1063/1.1589482] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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41
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Intermolecular photochemical proton transfer in solution: new insights and perspectives. J Photochem Photobiol A Chem 2002. [DOI: 10.1016/s1010-6030(02)00304-0] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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42
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Investigation of excited-state proton transfer in 2-naphthol derivatives containing a carboxyl group in organic solvents and in methanol–water mixtures. J Photochem Photobiol A Chem 2002. [DOI: 10.1016/s1010-6030(02)00262-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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43
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Tolbert LM, Solntsev KM. Excited-state proton transfer: from constrained systems to "super" photoacids to superfast proton transfer. Acc Chem Res 2002; 35:19-27. [PMID: 11790085 DOI: 10.1021/ar990109f] [Citation(s) in RCA: 610] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have used knowledge of the electronic structure of excited states of acids to design molecules that exhibit enhanced excited-state acidity. Such "super" photoacids are the strongest reversible photoacids known and allow the time evolution of proton transfer to be examined in a wide array of organic solvents. This includes breaking/formation of the hydrogen bonds in hundreds of femtoseconds, solvent reorientation and relaxation in picoseconds, proton dissociation, and, finally, diffusion and geminate recombination of the dissociated proton, observed in nanoseconds.
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Affiliation(s)
- Laren M Tolbert
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA
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44
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Cheatum CM, Heckscher MM, Fleming Crim F. Excited-state dynamics in 8-hydroxyquinoline dimers. Chem Phys Lett 2001. [DOI: 10.1016/s0009-2614(01)01173-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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45
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Penedo JC, Mosquera M, Rodríguez-Prieto F. Role of Hydrogen-Bonded Adducts in Excited-State Proton-Transfer Processes. J Phys Chem A 2000. [DOI: 10.1021/jp001473v] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. Carlos Penedo
- Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Spain
| | - Manuel Mosquera
- Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Spain
| | - Flor Rodríguez-Prieto
- Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Spain
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46
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Solntsev KM, Huppert D, Agmon N, Tolbert LM. Photochemistry of “Super” Photoacids. 2. Excited-State Proton Transfer in Methanol/Water Mixtures. J Phys Chem A 2000. [DOI: 10.1021/jp994454y] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kyril M. Solntsev
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, 69978, Israel, Department of Physical Chemistry and Fritz Haber Research Center, The Hebrew University, Jerusalem, 91904, Israel, and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, 30332-0400
| | - Dan Huppert
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, 69978, Israel, Department of Physical Chemistry and Fritz Haber Research Center, The Hebrew University, Jerusalem, 91904, Israel, and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, 30332-0400
| | - Noam Agmon
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, 69978, Israel, Department of Physical Chemistry and Fritz Haber Research Center, The Hebrew University, Jerusalem, 91904, Israel, and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, 30332-0400
| | - Laren M. Tolbert
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, 69978, Israel, Department of Physical Chemistry and Fritz Haber Research Center, The Hebrew University, Jerusalem, 91904, Israel, and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, 30332-0400
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