1
|
Matsuoka R, Kimura S, Miura T, Ikoma T, Kusamoto T. Single-Molecule Magnetoluminescence from a Spatially Confined Persistent Diradical Emitter. J Am Chem Soc 2023. [PMID: 37311307 DOI: 10.1021/jacs.3c01076] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Luminescent radicals are an emerging class of materials that exhibit unique photofunctions not found in closed-shell molecules due to their open-shell electronic structure. Particularly promising are photofunctions in which radical's spin and luminescence are correlated; for example, when a magnetic field can affect luminescence (i.e., magnetoluminescence, ML). These photofunctions could be useful in the new science of spin photonics. However, previous observations of ML in radicals have been limited to systems in which radicals are randomly doped in host crystals or polymerized through metal complexation. This study shows that a covalently linked luminescent radical dimer (diradical) can exhibit ML as a single-molecular property. This facilitates detailed elucidation of the requirements for and mechanisms of ML in radicals and can aid the rational design of ML-active radicals based on synthetic chemistry.
Collapse
Affiliation(s)
- Ryota Matsuoka
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193, Japan
| | - Shojiro Kimura
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Tomoaki Miura
- Department of Chemistry, Faculty of Science, Niigata University, Niigata, 950-2181, Japan
| | - Tadaaki Ikoma
- Department of Chemistry, Faculty of Science, Niigata University, Niigata, 950-2181, Japan
| | - Tetsuro Kusamoto
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
- SOKENDAI (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa 240-0193, Japan
- JST-PRESTO, 4-1-8, Honcho, Kawaguchi, Saitama, 332-0012, Japan
| |
Collapse
|
2
|
Buck JT, Mani T. Magnetic Control of Recombination Fluorescence and Tunability by Modulation of Radical Pair Energies in Rigid Donor–Bridge–Acceptor Systems. J Am Chem Soc 2020; 142:20691-20700. [DOI: 10.1021/jacs.0c09146] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jason T. Buck
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
| | - Tomoyasu Mani
- Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, United States
- PRESTO, JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| |
Collapse
|
3
|
Angulo G, Rosspeintner A. Bimolecular photo-induced electron transfer enlightened by diffusion. J Chem Phys 2020; 153:040902. [PMID: 32752717 DOI: 10.1063/5.0014384] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Photochemical electron transfer between freely diffusing molecules has been studied extensively. Here, we try to elucidate how much these works have contributed to the understanding of electron transfer. To this end, we have revisited the work performed in the experimental and theoretical areas of concern from the beginning of the 20th century up to the present day. We present a critical look at the major contributions and compile the current picture of a variety of phenomena around electron transfer in solution. This is based on two main developments, besides the theory of Marcus: encounter theories of diffusion and laser techniques in time-resolved spectroscopy.
Collapse
Affiliation(s)
- Gonzalo Angulo
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Arnulf Rosspeintner
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| |
Collapse
|
4
|
Verma P, Rosspeintner A, Kumpulainen T. Propyl acetate/butyronitrile mixture is ideally suited for investigating the effect of dielectric stabilization on (photo)chemical reactions. RSC Adv 2020; 10:23682-23689. [PMID: 35517311 PMCID: PMC9054732 DOI: 10.1039/d0ra04525j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 06/12/2020] [Indexed: 11/21/2022] Open
Abstract
Characterization of propyl acetate/butyronitrile (PA/BuCN) mixtures by various spectroscopic techniques is described. The neat solvents have identical viscosities and refractive indices but their dielectric constants differ significantly. Detailed solvatochromic and titration data show that the mixtures do not exhibit specific solute-solvent interactions or significant dielectric enrichment effects. Therefore, the mixtures are ideally suited for investigating the effect of dielectric stabilization on (photo)chemical reactions. Dynamic Stokes shift experiments performed on two push-pull probes demonstrate that the solvation dynamics are significantly decelerated in the mixtures as compared to the neat solvents. Therefore, the mixtures allow for varying both the extent and time scale of the dielectric stabilization in a predictable manner.
Collapse
Affiliation(s)
- Pragya Verma
- Department of Physical Chemistry, University of Geneva 30 Quai Ernest Ansermet Geneva Switzerland +41 22 379 6518 +41 22 379 6530
| | - Arnulf Rosspeintner
- Department of Physical Chemistry, University of Geneva 30 Quai Ernest Ansermet Geneva Switzerland +41 22 379 6518 +41 22 379 6530
| | - Tatu Kumpulainen
- Department of Physical Chemistry, University of Geneva 30 Quai Ernest Ansermet Geneva Switzerland +41 22 379 6518 +41 22 379 6530
| |
Collapse
|
5
|
Kim D, Lee YJ, Ahn DH, Song JW, Seo J, Lee H. Peptoid-Conjugated Magnetic Field-Sensitive Exciplex System at High and Low Solvent Polarities. J Phys Chem Lett 2020; 11:4668-4677. [PMID: 32441939 DOI: 10.1021/acs.jpclett.0c00636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The magnetic field effect (MFE) in exciplex emission (ExE) has been studied for decades, but it has been observed to occur only in solvents with a limited range of polarity. This limitation is mainly due to the reversible interconversion collapse between two quenching products of the photoinduced electron transfer, the exciplex and magnetic field-sensitive radical ion pair (RIP) beyond that polarity range. In a nonpolar solvent, the formation of RIPs is suppressed, whereas in a polar solvent, the probability of their re-encounter forming the exciplexes decreases. In this study, we developed new exciplex-forming (phenyl-phenanthrene)-(phenyl-N,N-dimethylaniline)-peptoid conjugates (PhD-PCs) to overcome this limitation. The well-defined peptoid structure allows precise control of the distance and the relative orientation between two conjugated moieties. Steady-state and time-resolved spectroscopic data indicate that the PhD-PCs can maintain the reversibility, which allows MFEs in ExE regardless of the solvent polarity. Subtle differences between the ExEs of the PhD-PCs were observed and explained by their exciplex geometries obtained through time-dependent density functional theory (TD-DFT) calculations.
Collapse
Affiliation(s)
- Dongkyum Kim
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdan Gwagiro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Yen Jea Lee
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdan Gwagiro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Dae-Hwan Ahn
- Department of Chemistry Education, Daegu University, Gyeongsan-si 113-8656, Republic of Korea
| | - Jong-Won Song
- Department of Chemistry Education, Daegu University, Gyeongsan-si 113-8656, Republic of Korea
| | - Jiwon Seo
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdan Gwagiro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Hohjai Lee
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), 123 Cheomdan Gwagiro, Buk-gu, Gwangju 61005, Republic of Korea
| |
Collapse
|
6
|
Atkins C, Bajpai K, Rumball J, Kattnig DR. On the optimal relative orientation of radicals in the cryptochrome magnetic compass. J Chem Phys 2019. [DOI: 10.1063/1.5115445] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Chadsley Atkins
- Institute and Department of Physics, University of Exeter, North Park Road, Exeter EX4 4QL, United Kingdom
| | - Kieran Bajpai
- Institute and Department of Physics, University of Exeter, North Park Road, Exeter EX4 4QL, United Kingdom
| | - Jeremy Rumball
- Institute and Department of Physics, University of Exeter, North Park Road, Exeter EX4 4QL, United Kingdom
| | - Daniel R. Kattnig
- Institute and Department of Physics, University of Exeter, North Park Road, Exeter EX4 4QL, United Kingdom
- Living Systems Institute and Department of Physics, University of Exeter, Stocker Road, Exeter EX4 4QD, United Kingdom
| |
Collapse
|
7
|
Hoang HM, Pham VTB, Grampp G, Kattnig DR. Magnetic Field-Sensitive Radical Pair Dynamics in Polymethylene Ether-Bridged Donor-Acceptor Systems. ACS OMEGA 2018; 3:10296-10305. [PMID: 30198006 PMCID: PMC6120740 DOI: 10.1021/acsomega.8b01232] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 08/20/2018] [Indexed: 05/13/2023]
Abstract
Donor-acceptor systems forming exciplexes are versatile models for the study of magnetic field effects (MFEs) on charge recombination reactions. The MFEs originate from singlet-triplet interconversion within transient radical ion pairs (RIPs), which exist in a dynamic equilibrium with the exciplexes. Here, we describe the synthesis and MFEs of the chain-linked N,N-dimethylaniline (DMA)/9-methylanthracene (MAnt) donor-acceptor system MAnt-(CH2) n -O-CH2-CH2-DMA for n = 6, 8, 10, and 16. The MFEs are found to increase with increasing chain length. Effects as large as 37.5% have been observed for the long-chain compound with n = 16. The solvent dependence of the MFEs at magnetic field intensity 75 mT is reported. For the range of solvent static dielectric constants εs = 6.0-36.0, the MFEs go through a maximum for intermediate polarities, for which the direct formation of RIPs prevails and their dissociation and reencounter are balanced. Field-resolved measurements (MARY spectra) are reported for solutions in butyronitrile. The MARY spectra reveal that for n = 8, 10, 16, the average exchange interaction is negligible during the coherent lifetime of the radical pair. However, singlet-triplet dephasing broadens the lineshape; the shorter the linker, the more pronounced this effect is. For n = 6, a dip in the fluorescence intensity reveals a nonzero average exchange coupling of the order of ±5 mT. We discuss the field-dependence in the framework of the semiclassical theory taking spin-selective recombination, singlet-triplet dephasing, and exchange coupling into account. Singlet recombination rates of the order of 0.1 ns-1 and various degrees of singlet-triplet dephasing govern the spin dynamics. In addition, because of a small free energy gap between the exciplex and the locally excited fluorophore quencher pair, a fully reversible interconversion between the RIP, exciplex, and locally excited fluorophore is revealed by spectrally resolved MFE measurements for the long-chain systems (n = 10, 16).
Collapse
Affiliation(s)
- Hao Minh Hoang
- Ho
Chi Minh City University of Technology and Education, Vo Van Ngan 01, Linh Chieu Ward, Thu Duc District, Ho Chi Minh City 700000, Vietnam
- Institute
of Physical and Theoretical Chemistry, Graz
University of Technology, Stremayrgasse 9/I, A-8010 Graz, Austria
| | - Van Thi Bich Pham
- Institute
of Physical and Theoretical Chemistry, Graz
University of Technology, Stremayrgasse 9/I, A-8010 Graz, Austria
| | - Günter Grampp
- Institute
of Physical and Theoretical Chemistry, Graz
University of Technology, Stremayrgasse 9/I, A-8010 Graz, Austria
| | - Daniel R. Kattnig
- Living
Systems Institute and Department of Physics, University of Exeter, Stocker Road, Exeter, Devon EX4 4QD, United Kingdom
| |
Collapse
|
8
|
Angulo G, Rosspeintner A, Lang B, Vauthey E. Optical transient absorption experiments reveal the failure of formal kinetics in diffusion assisted electron transfer reactions. Phys Chem Chem Phys 2018; 20:25531-25546. [DOI: 10.1039/c8cp05153d] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The charge separation yield is shown to be strongly influenced by the distance dependence of the reactivity, viscosity and concentration and cannot be disentangled from the preceding events.
Collapse
Affiliation(s)
- Gonzalo Angulo
- Institute of Physical Chemistry
- Polish Academy of Sciences
- 01-224 Warsaw
- Poland
| | - Arnulf Rosspeintner
- Department of Physical Chemistry
- University of Geneva
- CH-1211 Geneva
- Switzerland
| | - Bernhard Lang
- Department of Physical Chemistry
- University of Geneva
- CH-1211 Geneva
- Switzerland
| | - Eric Vauthey
- Department of Physical Chemistry
- University of Geneva
- CH-1211 Geneva
- Switzerland
| |
Collapse
|
9
|
Pham VTB, Hoang HM, Grampp G, Kattnig DR. Effects of Preferential Solvation Revealed by Time-Resolved Magnetic Field Effects. J Phys Chem B 2017; 121:2677-2683. [PMID: 28263599 PMCID: PMC5377269 DOI: 10.1021/acs.jpcb.7b00510] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
External
magnetic fields can impact recombination yields of photoinduced electron
transfer reactions by affecting the spin dynamics in transient, spin-correlated
radical pair intermediates. For exciplex-forming donor–acceptor
systems, this magnetic field effect (MFE) can be investigated sensitively
by studying the delayed recombination fluorescence. Here, we investigate
the effect of preferential solvation in microheterogeneous solvent
mixtures on the radical pair dynamics of the system 9,10-dimethylanthracene
(fluorophore)/N,N-dimethylaniline
(quencher) by means of time-resolved magnetic field effect (TR-MFE)
measurements, wherein the exciplex emission is recorded in the absence
and the presence of an external magnetic field using time-correlated
single photon counting (TCSPC). In microheterogeneous environments,
the MFE of the exciplex emission occurs on a faster time scale than
in iso-dielectric homogeneous solvents. In addition, the local polarity
reported by the exciplex is enhanced compared to homogeneous solvent
mixtures of the same macroscopic permittivity. Detailed analyses of
the TR-MFE reveal that the quenching reaction directly yielding the
radical ion pair is favored in microheterogeneous environments. This
is in stark contrast to homogeneous media, for which the MFE predominantly
involves direct formation of the exciplex, its subsequent dissociation
to the magneto-sensitive radical pair, and re-encounters. These observations
provide evidence for polar microdomains and enhanced caging, which
are shown to have a significant impact on the reaction dynamics in
microheterogeneous binary solvents.
Collapse
Affiliation(s)
- Van Thi Bich Pham
- Institute of Physical and Theoretical Chemistry, Graz University of Technology , Stremayrgasse 9/I, A-8010 Graz, Austria
| | - Hao Minh Hoang
- Institute of Physical and Theoretical Chemistry, Graz University of Technology , Stremayrgasse 9/I, A-8010 Graz, Austria.,Ho Chi Minh City University of Technology and Education , Vo Van Ngan 01, Linh Chieu Ward, Thu Duc District, Ho Chi Minh City, Vietnam
| | - Günter Grampp
- Institute of Physical and Theoretical Chemistry, Graz University of Technology , Stremayrgasse 9/I, A-8010 Graz, Austria
| | - Daniel R Kattnig
- Physical and Theoretical Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QZ, U.K
| |
Collapse
|
10
|
Angulo G, Milkiewicz J, Kattnig D, Nejbauer M, Stepanenko Y, Szczepanek J, Radzewicz C, Wnuk P, Grampp G. Influence of the excitation light intensity on the rate of fluorescence quenching reactions: pulsed experiments. Phys Chem Chem Phys 2017; 19:6274-6285. [PMID: 28195278 DOI: 10.1039/c6cp08562h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of multiple light excitation events on bimolecular photo-induced electron transfer reactions in liquid solution is studied experimentally. It is found that the decay of fluorescence can be up to 25% faster if a second photon is absorbed after a first cycle of quenching and recombination. A theoretical model is presented which ascribes this effect to the enrichment of the concentration of quenchers in the immediate vicinity of fluorophores that have been previously excited. Despite its simplicity, the model delivers a qualitative agreement with the observed experimental trends. The original theory by Burshtein and Igoshin (J. Chem. Phys., 2000, 112, 10930-10940) was created for continuous light excitation though. A qualitative extrapolation from the here presented pulse experiments to the continuous excitation conditions lead us to conclude that in the latter the order of magnitude of the increase of the quenching efficiency upon increasing the light intensity of excitation, must also be on the order of tens of percent. These results mean that the rate constant for photo-induced bimolecular reactions depends not only on the usual known factors, such as temperature, viscosity and other properties of the medium, but also on the intensity of the excitation light.
Collapse
Affiliation(s)
- Gonzalo Angulo
- Institute of Physical Chemistry, Polish Academy of Sciences, 44/52 Kasprzaka, 01-224 Warsaw, Poland.
| | - Jadwiga Milkiewicz
- Institute of Physical Chemistry, Polish Academy of Sciences, 44/52 Kasprzaka, 01-224 Warsaw, Poland.
| | - Daniel Kattnig
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Michał Nejbauer
- Institute of Physical Chemistry, Polish Academy of Sciences, 44/52 Kasprzaka, 01-224 Warsaw, Poland.
| | - Yuriy Stepanenko
- Institute of Physical Chemistry, Polish Academy of Sciences, 44/52 Kasprzaka, 01-224 Warsaw, Poland.
| | - Jan Szczepanek
- Institute of Physical Chemistry, Polish Academy of Sciences, 44/52 Kasprzaka, 01-224 Warsaw, Poland. and Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Czesław Radzewicz
- Institute of Physical Chemistry, Polish Academy of Sciences, 44/52 Kasprzaka, 01-224 Warsaw, Poland. and Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Paweł Wnuk
- Institute of Physical Chemistry, Polish Academy of Sciences, 44/52 Kasprzaka, 01-224 Warsaw, Poland. and Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland and Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany and Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, D-85748 Garching, Germany
| | - Günter Grampp
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| |
Collapse
|
11
|
Magin IM, Polyakov NE, Kruppa AI, Purtov PA, Leshina TV, Kiryutin AS, Miranda MA, Nuin E, Marin ML. Low field photo-CIDNP in the intramolecular electron transfer of naproxen-pyrrolidine dyads. Phys Chem Chem Phys 2015; 18:901-7. [PMID: 26648262 DOI: 10.1039/c5cp04233j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoinduced processes with partial (exciplex) and full charge transfer in donor-acceptor systems are of interest because they are frequently used for modeling drug-protein binding. Low field photo-CIDNP (chemically induced dynamic nuclear polarization) for these processes in dyads, including the drug, (S)- and (R)-naproxen and (S)-N-methyl pyrrolidine in solutions with strong and weak permittivity have been measured. The dramatic influence of solvent permittivity on the field dependence of the N-methyl pyrrolidine (1)H CIDNP effects has been found. The field dependences of both (R,S)- and (S,S)-dyads in a polar medium are the curves with a single extremum in the area of the S-T+ terms intersection. Moreover, the CIDNP field dependences of the same protons measured in a low polar medium present curves with several extrema. The shapes of the experimental CIDNP field dependence with two extrema have been described using the Green function approach for the calculation of the CIDNP effects in the system without electron exchange interactions. The article discusses the possible causes of the differences between the CIDNP field dependence detected in a low-permittivity solvent with the strong Coulomb interactions and in a polar solvent.
Collapse
Affiliation(s)
- I M Magin
- Institute of Chemical Kinetics and Combustion SB RAS, Institutskaya st. 3, 630090, Novosibirsk, Russia.
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Mentel KK, Nunes RMD, Serpa C, Arnaut LG. Dynamics of Radical Ion Pairs following Photoinduced Electron Transfer in Solvents with Low and Intermediate Polarities. J Phys Chem B 2015; 119:7571-8. [PMID: 25588979 DOI: 10.1021/jp511425y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Fluorescence quenching of p-xylene, naphthalene, or pyrene by fumaronitrile in apolar solvents and in solvents of intermediate polarities leads to weakly fluorescent radical ion pairs. This emission is assigned to ion pairs in close contact on the basis of their solvent polarity dependence, kinetics, and thermodynamics. The temperature-dependence of the intensity and fluorescence emission maxima of ion pairs in methyl acetate reveals that they have decay channels competitive with their thermal equilibration. The results presented in this work are consistent with the direct formation of contact ion pairs in weakly polar solvents and in solvents of intermediate polarities as the result of bimolecular photoinduced electron transfer reactions between aromatic hydrocarbons and nitriles. The implications of these findings in free-energy relationships of electron transfer reactions are discussed.
Collapse
Affiliation(s)
- Kamila K Mentel
- Chemistry Department, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Rui M D Nunes
- Chemistry Department, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Carlos Serpa
- Chemistry Department, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Luis G Arnaut
- Chemistry Department, University of Coimbra, 3004-535 Coimbra, Portugal
| |
Collapse
|
13
|
Rosspeintner A, Vauthey E. Bimolecular photoinduced electron transfer reactions in liquids under the gaze of ultrafast spectroscopy. Phys Chem Chem Phys 2014; 16:25741-54. [PMID: 25356933 DOI: 10.1039/c4cp03862b] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Because of their key role in many areas of science and technology, bimolecular photoinduced electron transfer reactions have been intensively studied over the past five decades. Despite this, several important questions, such as the absence of the Marcus inverted region or the structure of the primary reaction product, have only recently been solved while others still remain unanswered. Ultrafast spectroscopy has proven to be extremely powerful to monitor the entire electron transfer process and to access, with the help of state-of-the-art theoretical models of diffusion-assisted reactions, crucial information like e.g. the intrinsic charge separation dynamics beyond the diffusion limit. Additionally, extension of these experimental techniques to other spectral regions than the UV-visible, such as the infrared, has given a totally new insight into the nature, the structure and the dynamics of the key reaction intermediates, like exciplexes and ions pairs. In this perspective, we highlight these recent progresses and discuss several aspects that still need to be addressed before a thorough understanding of these processes can be attained.
Collapse
Affiliation(s)
- Arnulf Rosspeintner
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest Ansermet, Geneva, Switzerland.
| | | |
Collapse
|
14
|
Hoang HM, Pham TB, Grampp G, Kattnig DR. Exciplexes versus Loose Ion Pairs: How Does the Driving Force Impact the Initial Product Ratio of Photoinduced Charge Separation Reactions? J Phys Chem Lett 2014; 5:3188-3194. [PMID: 25243054 PMCID: PMC4166680 DOI: 10.1021/jz501575r] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Accepted: 08/29/2014] [Indexed: 05/24/2023]
Abstract
Many donor-acceptor systems can undergo a photoinduced charge separation reaction, yielding loose ion pairs (LIPs). LIPs can be formed either directly via (distant) electron transfer (ET) or indirectly via the dissociation of an initially formed exciplex or tight ion pair. Establishing the prevalence of one of the reaction pathways is challenging because differentiating initially formed exciplexes from LIPs is difficult due to similar spectroscopic footprints. Hence, no comprehensive reaction model has been established for moderately polar solvents. Here, we employ an approach based on the time-resolved magnetic field effect (MFE) of the delayed exciplex luminescence to distinguish the two reaction channels. We focus on the effects of the driving force of ET and the solvent permittivity. We show that, surprisingly, the exciplex channel is significant even for an exergonic ET system with a free energy of ET of -0.58 eV and for the most polar solutions studied (butyronitrile). Our findings demonstrate that exciplexes play a crucial role even in polar solvents and at moderate driving forces, contrary to what is usually assumed.
Collapse
Affiliation(s)
- Hao Minh Hoang
- Institute of Physical
and Theoretical Chemistry, Graz University of Technology, Streymayrgasse 9/I, A-8010 Graz, Austria
| | - Thi Bich
Van Pham
- Institute of Physical
and Theoretical Chemistry, Graz University of Technology, Streymayrgasse 9/I, A-8010 Graz, Austria
| | - Günter Grampp
- Institute of Physical
and Theoretical Chemistry, Graz University of Technology, Streymayrgasse 9/I, A-8010 Graz, Austria
| | - Daniel R. Kattnig
- Physical
and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, United Kingdom
| |
Collapse
|
15
|
Burshtein AI, Ivanov AI. Diffusion affected magnetic field effect in exciplex fluorescence. J Chem Phys 2014; 141:024508. [DOI: 10.1063/1.4886809] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - Anatoly I. Ivanov
- Volgograd State University, University Avenue, 100, Volgograd 400062, Russia
| |
Collapse
|
16
|
Koch M, Letrun R, Vauthey E. Exciplex Formation in Bimolecular Photoinduced Electron-Transfer Investigated by Ultrafast Time-Resolved Infrared Spectroscopy. J Am Chem Soc 2014; 136:4066-74. [DOI: 10.1021/ja500812u] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Marius Koch
- Department
of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Romain Letrun
- Department
of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Eric Vauthey
- Department
of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| |
Collapse
|
17
|
Asim S, Mansha A, Landgraf S, Grampp G, Zahid M, Bhatti HN. Spectral and thermodynamic properties for the exciplexes of N-alkyl carbazoles with dicyanobenzenes in THF. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 118:138-145. [PMID: 24051282 DOI: 10.1016/j.saa.2013.08.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Revised: 07/29/2013] [Accepted: 08/02/2013] [Indexed: 06/02/2023]
Abstract
The exciplex emission spectra of N-ethylcarbazole with 1,2-dicyanobenzene (NEC/1,2-DCB), N-methylcarbazole with 1,2-dicyanobenzene (NMC/1,2-DCB), 1,3-dicyanobenzene (NMC/1,3-DCB), and 1,4-dicyanobenzene (NMC/1,4-DCB) are studied in tetrahydrofuran (THF) for the temperature range starting from 253 K to 334 K. Thermochromic shifts along with the spectral properties including change in peak intensities and the ratio of exciplex peak intensity to fluorophore peak intensity are studied. Effect of temperature on the energy of zero-zero transitions hνo('), Huang-Rhys factor (S), Gauss broadening of vibronic level (σ) and the dominant high-frequency vibration (hνν) are also part of investigation. Enthalpy of exciplex formation (ΔH(EX)(∗)) calculated by the model proposed by A. Weller and the Gibb's energy of electron transfer (ΔG(et)(∗)) for all exciplex systems are also discussed in the present paper. All the exciplexes under study were observed to be dipolar in nature. The exciplex of the N-methylcarbazole/1,4-dicyanobenzene was found to be the most stable and the N-methylcarbazole/1,3-dicyanobenzene was the weakest exciplex system.
Collapse
Affiliation(s)
- Sadia Asim
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria; Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad, Pakistan(1).
| | | | | | | | | | | |
Collapse
|
18
|
Richert S, Rosspeintner A, Landgraf S, Grampp G, Vauthey E, Kattnig DR. Time-resolved magnetic field effects distinguish loose ion pairs from exciplexes. J Am Chem Soc 2013; 135:15144-52. [PMID: 24041160 PMCID: PMC3797520 DOI: 10.1021/ja407052t] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
We describe the experimental investigation
of time-resolved magnetic
field effects in exciplex-forming organic donor–acceptor systems.
In these systems, the photoexcited acceptor state is predominantly
deactivated by bimolecular electron transfer reactions (yielding radical
ion pairs) or by direct exciplex formation. The delayed fluorescence
emitted by the exciplex is magnetosensitive if the reaction pathway
involves loose radical ion pair states. This magnetic field effect
results from the coherent interconversion between the electronic singlet
and triplet radical ion pair states as described by the radical pair
mechanism. By monitoring the changes in the exciplex luminescence
intensity when applying external magnetic fields, details of the reaction
mechanism can be elucidated. In this work we present results obtained
with the fluorophore-quencher pair 9,10-dimethylanthracene/N,N-dimethylaniline (DMA) in solvents of
systematically varied permittivity. A simple theoretical model is
introduced that allows discriminating the initial state of quenching,
viz., the loose ion pair and the exciplex, based on the time-resolved
magnetic field effect. The approach is validated by applying it to
the isotopologous fluorophore-quencher pairs pyrene/DMA and pyrene-d10/DMA. We detect that both the exciplex and
the radical ion pair are formed during the initial quenching stage.
Upon increasing the solvent polarity, the relative importance of the
distant electron transfer quenching increases. However, even in comparably
polar media, the exciplex pathway remains remarkably significant.
We discuss our results in relation to recent findings on the involvement
of exciplexes in photoinduced electron transfer reactions.
Collapse
Affiliation(s)
- Sabine Richert
- Department of Physical Chemistry, University of Geneva , 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | | | | | | | | | | |
Collapse
|
19
|
Angulo G, Cuetos A, Rosspeintner A, Vauthey E. Experimental Evidence of the Relevance of Orientational Correlations in Photoinduced Bimolecular Reactions in Solution. J Phys Chem A 2013; 117:8814-25. [DOI: 10.1021/jp407203r] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Gonzalo Angulo
- Institute
of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224
Warsaw, Poland
| | - Alejandro Cuetos
- Department of Physical,
Chemical and Natural Systems, Universidad Pablo Olavide, 41013 Sevilla, Spain
| | - Arnulf Rosspeintner
- Department of Physical
Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Eric Vauthey
- Department of Physical
Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| |
Collapse
|
20
|
Pal K, Grampp G, Kattnig DR. Solvation dynamics of a radical ion pair in micro-heterogeneous binary solvents: a semi-quantitative study utilizing MARY line-broadening experiments. Chemphyschem 2013; 14:3389-99. [PMID: 23939826 DOI: 10.1002/cphc.201300435] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/15/2013] [Indexed: 11/10/2022]
Abstract
This work aims at elucidating the mechanism of solvation of a radical ion pair (RIP) in a micro-heterogeneous binary solvent mixture using magnetically affected reaction yield (MARY) spectroscopy. For the exciplex-forming 9,10-dimethylanthracene/N,N-dimethylaniline system a comparative, composition-dependent MARY line-broadening study is undertaken in a heterogeneous (toluene/dimethylsulfoxide) and a quasi-homogenous (propyl acetate/butyronitrile) solvent mixture. The half-saturation field extrapolated to zero-quencher concentration, B(1/2), and the self-exchange rate constants are analyzed in the light of solvent dynamical properties of the mixtures and a dielectric continuum solvation model. The dependence of B(1/2) on the solvent composition is explained by cluster formation giving rise to shortened RIP lifetimes. The results are in qualitative agreement with the continuum solvation model suggesting that it could serve as a theoretical basis for quantitative modeling.
Collapse
Affiliation(s)
- Kunal Pal
- Institute of Physical and Theoretical Chemistry, Graz University of Technolgy, Stremayrgasse 9/Z2, A-8010 Graz (Austria).
| | | | | |
Collapse
|
21
|
Xiao LH, Wang T, Zhao TY, Zheng X, Sun LY, Li P, Liu FQ, Gao G, Dong A. Fabrication of magnetic-antimicrobial-fluorescent multifunctional hybrid microspheres and their properties. Int J Mol Sci 2013; 14:7391-404. [PMID: 23549271 PMCID: PMC3645692 DOI: 10.3390/ijms14047391] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Revised: 02/26/2013] [Accepted: 03/07/2013] [Indexed: 11/25/2022] Open
Abstract
Novel magnetic-antimicrobial-fluorescent multifunctional hybrid microspheres with well-defined nanostructure were synthesized by the aid of a poly(glycidyl methacrylate) (PGMA) template. The hybrid microspheres were fully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and digital fluorescence microscope. The as-synthesized microspheres PGMA, amino-modified PGMA (NH2-PGMA) and magnetic PGMA (M-PGMA) have a spherical shape with a smooth surface and fine monodispersity. M-PGMA microspheres are super-paramagnetic, and their saturated magnetic field is 4.608 emu·g−1, which made M-PGMA efficiently separable from aqueous solution by an external magnetic field. After poly(haxemethylene guanidine hydrochloride) (PHGH) functionalization, the resultant microspheres exhibit excellent antibacterial performance against both Gram-positive and Gram-negative bacteria. The fluorescence feature originating from the quantum dot CdTe endowed the hybrid microspheres with biological functions, such as targeted localization and biological monitoring functions. Combination of magnetism, antibiosis and fluorescence into one single hybrid microsphere opens up the possibility of the extensive study of multifunctional materials and widens the potential applications.
Collapse
Affiliation(s)
- Ling-Han Xiao
- College of Chemistry and MacDiarmid Laboratory, Jilin University, Changchun 130021, China; E-Mails: (L.-H.X.); (T.W.); (T.-Y.Z.); (X.Z.); (L.-Y.S.); (P.L.); (F.-Q.L.)
| | - Tao Wang
- College of Chemistry and MacDiarmid Laboratory, Jilin University, Changchun 130021, China; E-Mails: (L.-H.X.); (T.W.); (T.-Y.Z.); (X.Z.); (L.-Y.S.); (P.L.); (F.-Q.L.)
| | - Tian-Yi Zhao
- College of Chemistry and MacDiarmid Laboratory, Jilin University, Changchun 130021, China; E-Mails: (L.-H.X.); (T.W.); (T.-Y.Z.); (X.Z.); (L.-Y.S.); (P.L.); (F.-Q.L.)
| | - Xin Zheng
- College of Chemistry and MacDiarmid Laboratory, Jilin University, Changchun 130021, China; E-Mails: (L.-H.X.); (T.W.); (T.-Y.Z.); (X.Z.); (L.-Y.S.); (P.L.); (F.-Q.L.)
| | - Li-Ying Sun
- College of Chemistry and MacDiarmid Laboratory, Jilin University, Changchun 130021, China; E-Mails: (L.-H.X.); (T.W.); (T.-Y.Z.); (X.Z.); (L.-Y.S.); (P.L.); (F.-Q.L.)
| | - Ping Li
- College of Chemistry and MacDiarmid Laboratory, Jilin University, Changchun 130021, China; E-Mails: (L.-H.X.); (T.W.); (T.-Y.Z.); (X.Z.); (L.-Y.S.); (P.L.); (F.-Q.L.)
| | - Feng-Qi Liu
- College of Chemistry and MacDiarmid Laboratory, Jilin University, Changchun 130021, China; E-Mails: (L.-H.X.); (T.W.); (T.-Y.Z.); (X.Z.); (L.-Y.S.); (P.L.); (F.-Q.L.)
| | - Ge Gao
- College of Chemistry and MacDiarmid Laboratory, Jilin University, Changchun 130021, China; E-Mails: (L.-H.X.); (T.W.); (T.-Y.Z.); (X.Z.); (L.-Y.S.); (P.L.); (F.-Q.L.)
- Authors to whom correspondence should be addressed; E-Mails: (G.G.); (A.D.); Tel.: +86-431-822-763-25 (G.G.); Fax: +86-431-884-991-87 (G.G.); Tel./Fax: +86-471-499-4363 (A.D.)
| | - Alideertu Dong
- College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
- Authors to whom correspondence should be addressed; E-Mails: (G.G.); (A.D.); Tel.: +86-431-822-763-25 (G.G.); Fax: +86-431-884-991-87 (G.G.); Tel./Fax: +86-471-499-4363 (A.D.)
| |
Collapse
|
22
|
Dodin DV, Ivanov AI, Burshtein AI. Hyperfine interaction mechanism of magnetic field effects in sequential fluorophore and exciplex fluorescence. J Chem Phys 2013; 138:124102. [DOI: 10.1063/1.4795576] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
23
|
Dodin DV, Ivanov AI, Burshtein AI. Magnetic field effect in fluorescence of excited fluorophore equilibrated with exciplex that reversibly dissociates into radical-ion pair undergoing the spin conversion. J Chem Phys 2012; 137:024511. [DOI: 10.1063/1.4734306] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
24
|
Pal K, Kattnig DR, Grampp G, Landgraf S. Experimental observation of preferential solvation on a radical ion pair using MARY spectroscopy. Phys Chem Chem Phys 2012; 14:3155-61. [PMID: 22286393 DOI: 10.1039/c2cp23858f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effect of preferential solvation on the exciplex luminescence detected magnetic field effect has been studied using magnetic-field-effect-on-reaction-yield (MARY) spectroscopy. By designing solvent mixtures which can provide a micro-environment around the magneto-sensitive radical ion pair (RIP) from highly heterogeneous to quasi-homogenous, the effect of the polarity scan on an absolute magnetic field effect (χ(E)) and B(1/2) (the field value marking half saturation) has been studied on the system 9,10-dimethylanthracene (fluorophore)/N,N'-dimethylaniline (quencher). While the trend in χ(E) (although with subtle differences) follows the usual norm of passing through maxima with increasing polarity, the B(1/2) values show either a large monotonic decrease (for heterogeneous solvents) or remain constant (for quasi-homogenous systems) with increasing polarity. The observations have been interpreted invoking the concept of amplification of the "cage-effect" as a result of preferential solvation in binary solvents and its influence on the decaying exciplex. The use of ternary solvents further confirms the proposed mechanism. Additionally electron hopping from the radical ion pair to the surrounding neutral donor molecules could also possibly contribute to the observed trend.
Collapse
Affiliation(s)
- Kunal Pal
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9/I, A-8010 Graz, Austria
| | | | | | | |
Collapse
|
25
|
Preparation of magnetically separable N-halamine nanocomposites for the improved antibacterial application. J Colloid Interface Sci 2011; 364:333-40. [DOI: 10.1016/j.jcis.2011.08.036] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Revised: 08/14/2011] [Accepted: 08/17/2011] [Indexed: 11/17/2022]
|
26
|
Awasthi K, Ohta N. Magnetic field effects on electro-photoluminescence of photoinduced electron transfer systems in a polymer film. J Photochem Photobiol A Chem 2011. [DOI: 10.1016/j.jphotochem.2011.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
27
|
|
28
|
Kattnig DR, Rosspeintner A, Grampp G. Magnetic field effects on exciplex-forming systems: the effect on the locally excited fluorophore and its dependence on free energy. Phys Chem Chem Phys 2010; 13:3446-60. [PMID: 21180733 DOI: 10.1039/c0cp01517b] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
This study addresses magnetic field effects in exciplex forming donor-acceptor systems. For moderately exergonic systems, the exciplex and the locally excited fluorophore emission are found to be magneto-sensitive. A previously introduced model attributing this finding to excited state reversibility is confirmed. Systems characterised by a free energy of charge separation up to approximately -0.35 eV are found to exhibit a magnetic field effect on the fluorophore. A simple three-state model of the exciplex is introduced, which uses the reaction distance and the asymmetric electron transfer reaction coordinate as pertinent variables. Comparing the experimental emission band shapes with those predicted by the model, a semi-quantitative picture of the formation of the magnetic field effect is developed based on energy hypersurfaces. The model can also be applied to estimate the indirect contribution of the exchange interaction, even if the perturbative approach fails. The energetic parameters that are essential for the formation of large magnetic field effects on the exciplex are discussed.
Collapse
|
29
|
Awasthi K, Iimori T, Ohta N. Synergy Effects of Electric and Magnetic Fields on Locally Excited-State Fluorescence of Photoinduced Electron Transfer Systems in a Polymer Film. J Phys Chem A 2009; 113:10603-9. [DOI: 10.1021/jp905579p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kamlesh Awasthi
- Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan
| | - Toshifumi Iimori
- Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan
| | - Nobuhiro Ohta
- Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan
| |
Collapse
|
30
|
Rosspeintner A, Kattnig DR, Angulo G, Landgraf S, Grampp G. The Rehm-Weller experiment in view of distant electron transfer. Chemistry 2008; 14:6213-21. [PMID: 18506871 DOI: 10.1002/chem.200701841] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The driving-force dependence of bimolecular fluorescence quenching by electron transfer in solution, the Rehm-Weller experiment, is revisited. One of the three long-standing unsolved questions about the features of this experiment is carefully analysed here, that is, is there a diffusional plateau? New experimental quenching rates are compiled for a single electron donor, 2,5-bis(dimethylamino)-1,3-benzenedicarbonitrile, and eighteen electron acceptors in acetonitrile. The data are analysed in the framework of differential encounter theory by using an extended version of the Marcus theory to model the intrinsic electron-transfer step. Only by including the hydrodynamic effect and the solvent structure can the experimental findings be well modelled. The diffusional control region, the "plateau", reveals the inherent distance dependence of the reaction, which is shown to be a general feature of electron transfer in solution.
Collapse
Affiliation(s)
- A Rosspeintner
- Graz University of Technology, Technikerstrasse 4/I, 8010 Graz, Austria
| | | | | | | | | |
Collapse
|