1
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Mayer D, Lever F, Gühr M. Time-resolved x-ray spectroscopy of nucleobases and their thionated analogs. Photochem Photobiol 2024; 100:275-290. [PMID: 38174615 DOI: 10.1111/php.13903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/05/2024]
Abstract
The photoinduced relaxation dynamics of nucleobases and their thionated analogs have been investigated extensively over the past decades motivated by their crucial role in organisms and their application in medical and biochemical research and treatment. Most of these studies focused on the spectroscopy of valence electrons and fragmentation. The advent of ultrashort x-ray laser sources such as free-electron lasers, however, opens new opportunities for studying the ultrafast molecular relaxation dynamics utilizing the site- and element-selectivity of x-rays. In this review, we want to summarize ultrafast experiments on thymine and 2-thiouracil performed at free-electron lasers. We performed time-resolved x-ray absorption spectroscopy at the oxygen K-edge after UV excitation of thymine. In addition, we investigated the excited state dynamics of 2-tUra via x-ray photoelectron spectroscopy at sulfur. For these methods, we show a strong sensitivity to the electronic state or charge distribution, respectively. We also performed time-resolved Auger-Meitner spectroscopy, which shows spectral shifts associated with internuclear distances close to the probed site. We discuss the complementary aspects of time-resolved x-ray spectroscopy techniques compared to optical and UV spectroscopy for the investigation of ultrafast relaxation processes.
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Affiliation(s)
- Dennis Mayer
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - Fabiano Lever
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - Markus Gühr
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
- Institute of Physical Chemistry, University of Hamburg, Hamburg, Germany
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2
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Mathew R, Verma P, Barak A, Adithya Lakshmanna Y. Excited-State Dynamics in 4-[4'(Dimethylamino)styryl]pyridine, a Photobase: Role of Photoinitiated Proton-Coupled Electron Transfer. J Phys Chem A 2023; 127:7419-7428. [PMID: 37647516 DOI: 10.1021/acs.jpca.3c02502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
The photoinitiated proton-coupled electron transfer (PCET) process in photoacid-based adducts is predominantly governed by the evolution of the electron-proton transfer state. However, such a process is underexplored in the case of photobases as the excited states evolve through multiple competitive channels. Here, we elucidate the excited-state dynamics of a photobase, 4-[4'-(dimethylamino)styryl]pyridine (DMASP), in the presence of hexafluoroisopropanol (HFIP) that enables PCET. Transient absorption measurements show the evolution of a protonated species in the excited state with a time constant of ∼2.5 ps. Fluorescence upconversion measurements reveal the signatures of an emissive intramolecular charge transfer state and a protonated state. The role of such states is further confirmed by time-resolved measurements in the presence of trifluoroacetic acid and computational analysis. Furthermore, the proton-abstraction dynamics of DMASP is analyzed in bulk methanol and butanol solvents. The extent of proton abstraction by DMASP is found to be higher in the presence of HFIP when compared with the normal alcohols over a time period of a few picoseconds.
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Affiliation(s)
- Reshma Mathew
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Vithura, Thiruvananthapuram 695551, India
| | - Preetika Verma
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Vithura, Thiruvananthapuram 695551, India
| | - Arvind Barak
- Department of Inorganic and Physical Chemistry, Indian Institute of Science Bangalore, Bangalore 560012, India
| | - Yapamanu Adithya Lakshmanna
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Vithura, Thiruvananthapuram 695551, India
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3
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Cherneva TD, Todorova MM, Bakalska RI, Shterev IG, Horkel E, Delchev VB. Experimental and theoretical study of the cytosine tautomerism through excited states. J Mol Model 2023; 29:303. [PMID: 37665380 DOI: 10.1007/s00894-023-05707-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 08/23/2023] [Indexed: 09/05/2023]
Abstract
CONTEXT The irradiation of water solution of cytosine with UV light (λmax = 254 nm) shows oxo-hydroxy tautomerism with a rate constant of 6.297 × 10-3 min-1. The order of the reaction implies a tautomeric conversion. After removing the UV light source, we observed a dark reaction with a rate constant of 1.473 × 10-3 min-1 which leads to a restoration of the initial tautomer as before the irradiation. The mechanism of oxo-hydroxy tautomerism of cytosine in water solution was studied in the excited state. It was found that the transformations occur along the 1πσ* excited-state reaction paths which link the Franck-Condon geometries of the tautomers and the conical intersections S0/S1 connected with the H-detachment processes of the corresponding bonds. Furthermore, we established that the conical intersections S0/S1 are also mutually accessible along the 1πσ* excited-state reaction paths. METHODS The ground-state equilibrium geometries were optimized at the B3LYP/aug-cc-pVDZ level of theory in water environment according to PCM as well as at the CC2/aug-cc-pVDZ level in the gas phase. The TD B3LYP and CC2 methods were applied for the study of the excited states. The tautomerization mechanisms were studied with the use of the linear interpolation in internal coordinates approach using the optimized geometries of tautomers minima and conical intersections S0/S1 at the CASSCF(6,6)/6-31G* level. All calculations were performed with the GAUSSIAN 16 commercial software.
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Affiliation(s)
- Tsvetina D Cherneva
- Faculty of Chemistry, University of Plovdiv, Tzar Assen 24 Str, 4000, Plovdiv, Bulgaria
| | - Mina M Todorova
- Faculty of Chemistry, University of Plovdiv, Tzar Assen 24 Str, 4000, Plovdiv, Bulgaria
| | - Rumyana I Bakalska
- Faculty of Chemistry, University of Plovdiv, Tzar Assen 24 Str, 4000, Plovdiv, Bulgaria
| | - Ivan G Shterev
- Department of Inorganic and Physical Chemistry, University of Food Technologies, 4002, Plovdiv, Bulgaria
| | - Ernst Horkel
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9, 1060, Vienna, Austria
| | - Vassil B Delchev
- Faculty of Chemistry, University of Plovdiv, Tzar Assen 24 Str, 4000, Plovdiv, Bulgaria.
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4
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Christopoulou G, Tran T, Worth GA. Direct nonadiabatic quantum dynamics simulations of the photodissociation of phenol. Phys Chem Chem Phys 2021; 23:23684-23695. [PMID: 34642723 DOI: 10.1039/d1cp01843d] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gaussian wavepacket methods are becoming popular for the investigation of nonadiabatic molecular dynamics. In the present work, a recently developed efficient algorithm for the Direct Dynamics variational Multi-Configurational Gaussian (DD-vMCG) method has been used to describe the multidimensional photodissociation dynamics of phenol including all degrees of freedom. Full-dimensional quantum dynamic calculations including for the first time six electronic states (1ππ, 11ππ*, 11πσ*, 21πσ*, 21ππ*, 31ππ*), along with a comparison to an existing analytical 4-state model for the potential energy surfaces are presented. Including the fifth singlet excited state is shown to have a significant effect on the nonadiabatic photodissociation of phenol to the phenoxyl radical and hydrogen atom. State population and flux analysis from the DD-vMCG simulations of phenol provided further insights into the decay mechanism, confirming the idea of rapid relaxation to the ground state through the 1ππ/11πσ* conical intersection.
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Affiliation(s)
| | - Thierry Tran
- Department of Chemistry, University College London, London WC1H 0AJ, UK.,Department of Chemistry, Imperial College London, Imperial College London, White City Campus, W12 0BZ London, UK.
| | - Graham A Worth
- Department of Chemistry, University College London, London WC1H 0AJ, UK
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5
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6
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Yankov EP, Bakalska RI, Horkel E, Svatunek D, Delchev VB. Experimental and theoretical study of the excited-state tautomerism of 6-azauracil in water surroundings. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.07.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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7
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Lin YC, Lee C, Lee SH, Lee YY, Lee YT, Tseng CM, Ni CK. Excited-state dissociation dynamics of phenol studied by a new time-resolved technique. J Chem Phys 2018; 148:074306. [PMID: 29471658 DOI: 10.1063/1.5016059] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Phenol is an important model molecule for the theoretical and experimental investigation of dissociation in the multistate potential energy surfaces. Recent theoretical calculations [X. Xu et al., J. Am. Chem. Soc. 136, 16378 (2014)] suggest that the phenoxyl radical produced in both the X and A states from the O-H bond fission in phenol can contribute substantially to the slow component of photofragment translational energy distribution. However, current experimental techniques struggle to separate the contributions from different dissociation pathways. A new type of time-resolved pump-probe experiment is described that enables the selection of the products generated from a specific time window after molecules are excited by a pump laser pulse and can quantitatively characterize the translational energy distribution and branching ratio of each dissociation pathway. This method modifies conventional photofragment translational spectroscopy by reducing the acceptance angles of the detection region and changing the interaction region of the pump laser beam and the molecular beam along the molecular beam axis. The translational energy distributions and branching ratios of the phenoxyl radicals produced in the X, A, and B states from the photodissociation of phenol at 213 and 193 nm are reported. Unlike other techniques, this method has no interference from the undissociated hot molecules. It can ultimately become a standard pump-probe technique for the study of large molecule photodissociation in multistates.
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Affiliation(s)
- Yen-Cheng Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Chin Lee
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Shih-Huang Lee
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Yin-Yu Lee
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Yuan T Lee
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Chien-Ming Tseng
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Chi-Kung Ni
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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8
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Marchetti B, Karsili TNV, Ashfold MNR, Domcke W. A 'bottom up', ab initio computational approach to understanding fundamental photophysical processes in nitrogen containing heterocycles, DNA bases and base pairs. Phys Chem Chem Phys 2018; 18:20007-27. [PMID: 26980149 DOI: 10.1039/c6cp00165c] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The availability of non-radiative decay mechanisms by which photoexcited molecules can revert to their ground electronic state, without experiencing potentially deleterious chemical transformation, is fundamental to molecular photostability. This Perspective Article combines results of new ab initio electronic structure calculations and prior experimental data in an effort to systematise trends in the non-radiative decay following UV excitation of selected families of heterocyclic molecules. We start with the prototypical uni- and bicyclic molecules phenol and indole, and explore the structural and photophysical consequences of incorporating progressively more nitrogen atoms within the respective ring structures en route to the DNA bases thymine, cytosine, adenine and guanine. For each of the latter, we identify low energy non-radiative decay pathways via conical intersections with the ground state potential energy surface accessed by out-of-plane ring deformations. This is followed by summary descriptions and illustrations of selected rival (electron driven H atom transfer) non-radiative excited state decay processes that demand consideration once the nucleobases are merely components in larger biomolecular systems like nucleosides, and both individual and stacked base-pairs.
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Affiliation(s)
- Barbara Marchetti
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - Tolga N V Karsili
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK. and Department of Chemistry, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
| | - Michael N R Ashfold
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - Wolfgang Domcke
- Department of Chemistry, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
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9
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Chakraborty R, Bose S, Ghosh D. Effect of solvation on the ionization of guanine nucleotide: A hybrid QM/EFP study. J Comput Chem 2017; 38:2528-2537. [PMID: 28856705 DOI: 10.1002/jcc.24913] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/20/2017] [Accepted: 07/24/2017] [Indexed: 11/11/2022]
Abstract
Ionization of nucleobases is affected by their biological environment, which includes both the effect of adjacent nucleotides as well as the presence of water around it. Guanine and its nucleotide have the lowest ionization potentials among the various DNA bases. Therefore, the threshold of ionization is dependent on that of guanine and its characterization is crucial to the prediction of interaction of light with DNA. We investigate the effect of solvation on the vertical ionization energies (VIEs) of guanine and its nucleotide. In this work, we have used hybrid quantum mechanics/molecular mechanics (QM/MM) approach with effective fragment potential as the MM method of choice and equation-of-motion coupled-cluster for ionization potential with singles and doubles (EOM-IP-CCSD) as the QM method. The performance of the hybrid scheme with respect to the full QM method shows an accuracy of ≤ 0.02-0.04 eV. The lowest few ionizations of the nucleotide are found to be from different parts of the moiety, that is, the nucleic acid base, phosphate, or sugar, and these ionization energies are very closely spaced giving rise to a very complicated spectrum. Furthermore, microsolvation has large effects on these ionizations and can lead to red or blue shift depending on the position of the water molecule. Even a single water molecule can change the order of ionized states in the nucleotide. The VIEs of the bulk solvated chromophores are predicted and compared to existing experimental spectra. The predominant role of polarization in the solvatochromic shift is noticed. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Rahul Chakraborty
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Kolkata, 700032, India
| | - Samik Bose
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Kolkata, 700032, India
| | - Debashree Ghosh
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Kolkata, 700032, India
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10
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Bose S, Ghosh D. An interaction energy driven biased sampling technique: A faster route to ionization spectra in condensed phase. J Comput Chem 2017; 38:2248-2257. [DOI: 10.1002/jcc.24875] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/06/2017] [Accepted: 06/19/2017] [Indexed: 01/09/2023]
Affiliation(s)
- Samik Bose
- Physical and Materials Chemistry Division; CSIR-National Chemical Laboratory; Pune 411008 India
| | - Debashree Ghosh
- Department of Physical Chemistry; Indian Association for the Cultivation of Science; Kolkata 700032 India
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11
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Maity S, Mazumdar P, Shyamal M, Sahoo GP, Misra A. Crystal induced phosphorescence from Benz(a)anthracene microcrystals at room temperature. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2016; 157:61-68. [PMID: 26720419 DOI: 10.1016/j.saa.2015.12.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 11/27/2015] [Accepted: 12/02/2015] [Indexed: 06/05/2023]
Abstract
Pure organic compounds that are also phosphorescent at room temperature are very rare in literature. Here, we report efficient phosphorescence emission from aggregated hydrosol of Benz(a)anthracene (BaA) at room temperature. Aggregated hydrosol of BaA has been synthesized by re-precipitation method and SDS is used as morphology directing agent. Morphology of the particles is characterized using optical and scanning electronic microcopy (SEM). Photophysical properties of the aggregated hydrosol are carried out using UV-vis, steady state and time resolved fluorescence study. The large stoke shifted structured emission from aggregated hydrosol of BaA has been explained due to phosphorescence emission of BaA at room temperature. In the crystalline state, the restricted intermolecular motions (RIM) such as rotations and vibrations are activated by crystal lattice. This rigidification effect makes the chromophore phosphorescent at room temperature. The possible stacking arrangement of the neighboring BaA within the aggregates has been substantiated by computing second order Fukui parameter as local reactivity descriptors. Computational study also reveals that the neighboring BaA molecules are present in parallel slipped conformation in its aggregated crystalline form.
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Affiliation(s)
- Samir Maity
- Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore, 721 102, W.B., India
| | - Prativa Mazumdar
- Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore, 721 102, W.B., India
| | - Milan Shyamal
- Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore, 721 102, W.B., India
| | - Gobinda Prasad Sahoo
- Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore, 721 102, W.B., India
| | - Ajay Misra
- Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore, 721 102, W.B., India.
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12
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Xue B, Yabushita A, Kobayashi T. Ultrafast dynamics of uracil and thymine studied using a sub-10 fs deep ultraviolet laser. Phys Chem Chem Phys 2016; 18:17044-53. [DOI: 10.1039/c5cp07861j] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Single 9.6 fs deep ultraviolet pulses with a spectral range of 255–290 nm are generated by a chirped-pulse four-wave mixing technique for use as pump and probe pulses.
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Affiliation(s)
- Bing Xue
- Advanced Ultrafast Laser Research Centre and Department of Engineering Science
- Faculty of Informatics and Engineering
- University of Electro-Communications
- Chofu
- Japan
| | - Atsushi Yabushita
- Department of Electrophysics
- National Chiao Tung University
- Hsinchu 30010
- Taiwan
| | - Takayoshi Kobayashi
- Advanced Ultrafast Laser Research Centre and Department of Engineering Science
- Faculty of Informatics and Engineering
- University of Electro-Communications
- Chofu
- Japan
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13
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Omidyan R, Ataelahi M, Azimi G. Excited-state deactivation mechanisms of protonated and neutral phenylalanine: a theoretical study. RSC Adv 2015. [DOI: 10.1039/c5ra00630a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Minimum energy paths (MEPs) of protonated phenylalanine (PheH+) at the electronic ground and S1 (1ππ*) excited states along the Cα–Cβ bond stretching coordinate, following proton transfer to the aromatic chromophore.
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Affiliation(s)
- Reza Omidyan
- Department of Chemistry
- University of Isfahan
- 81746-73441 Isfahan
- Iran
| | - Mitra Ataelahi
- Department of Chemistry
- University of Isfahan
- 81746-73441 Isfahan
- Iran
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14
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Molesky BP, Giokas PG, Guo Z, Moran AM. Multidimensional resonance raman spectroscopy by six-wave mixing in the deep UV. J Chem Phys 2014; 141:114202. [DOI: 10.1063/1.4894846] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Brian P. Molesky
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Paul G. Giokas
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Zhenkun Guo
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Andrew M. Moran
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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15
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Photochemistry of Nucleic Acid Bases and Their Thio- and Aza-Analogues in Solution. Top Curr Chem (Cham) 2014; 355:245-327. [DOI: 10.1007/128_2014_554] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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16
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Li MJ, Liu MX, Zhao YY, Pei KM, Wang HG, Zheng X, Fang WH. Excited State Structures and Decay Dynamics of 1,3-Dimethyluracils in Solutions: Resonance Raman and Quantum Mechanical Calculation Study. J Phys Chem B 2013; 117:11660-9. [DOI: 10.1021/jp403798d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Ming-Juan Li
- Department of Chemistry and
Key Laboratory of Advanced Textiles Material and Manufacture Technology,
MOE, Zhejiang Sci-Tech University, Hangzhou, Zhejiang Province, 310023, People’s Republic of China
| | - Ming-Xia Liu
- Department of Chemistry and
Key Laboratory of Advanced Textiles Material and Manufacture Technology,
MOE, Zhejiang Sci-Tech University, Hangzhou, Zhejiang Province, 310023, People’s Republic of China
| | - Yan-Ying Zhao
- Department of Chemistry and
Key Laboratory of Advanced Textiles Material and Manufacture Technology,
MOE, Zhejiang Sci-Tech University, Hangzhou, Zhejiang Province, 310023, People’s Republic of China
| | - Ke-Mei Pei
- Department of Chemistry and
Key Laboratory of Advanced Textiles Material and Manufacture Technology,
MOE, Zhejiang Sci-Tech University, Hangzhou, Zhejiang Province, 310023, People’s Republic of China
| | - Hui-Gang Wang
- Department of Chemistry and
Key Laboratory of Advanced Textiles Material and Manufacture Technology,
MOE, Zhejiang Sci-Tech University, Hangzhou, Zhejiang Province, 310023, People’s Republic of China
| | - Xuming Zheng
- Department of Chemistry and
Key Laboratory of Advanced Textiles Material and Manufacture Technology,
MOE, Zhejiang Sci-Tech University, Hangzhou, Zhejiang Province, 310023, People’s Republic of China
| | - Wei Hai Fang
- Department
of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
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17
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West BA, Molesky BP, Giokas PG, Moran AM. Uncovering molecular relaxation processes with nonlinear spectroscopies in the deep UV. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2013.06.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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18
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West BA, Womick JM, Moran AM. Interplay between vibrational energy transfer and excited state deactivation in DNA components. J Phys Chem A 2012; 117:5865-74. [PMID: 22920964 DOI: 10.1021/jp306799e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Femtosecond laser spectroscopies are used to examine a thymine family of systems chosen to expose the interplay between excited state deactivation and two distinct vibrational energy transfer (VET) pathways: (i) VET from the base to the deoxyribose ring; (ii) VET between neighboring units in a dinucleotide. We find that relaxation in the ground electronic state accelerates markedly as the molecular sizes increase from the nucleobase to the dinucleotide. This behavior directly reflects growth in the density of vibrational quantum states on the substituent of the base. Excited state lifetimes are studied at temperatures ranging from 100 to 300 K to characterize the thermal fluctuations that connect the Franck-Condon geometries and the conical intersections leading back to the ground state. An Arrhenius analysis yields an approximate excited state energy barrier of 13 meV in the thymine dinucleotide. In addition, we find that the transfer of vibrational energy from the base to the substituent suppresses thermal fluctuations across this energy barrier. The possibility that the solvent viscosity imposes friction on the reaction coordinate is examined by comparing thymine and adenine systems. Experiments suggest that the solvent viscosity has little effect on barrier crossing dynamics in thymine because the conical intersection is accessed through relatively small out-of-plane atomic displacements. Overall, we conclude that the transfer of vibrational quanta from thymine to the deoxyribose ring couples significantly to the internal conversion rate, whereas the neighboring unit in the dinucleotide serves as a secondary heat bath. In natural DNA, it follows that (local) thermal fluctuations in the geometries of subunits involving the base and deoxyribose ring are most important to this subpicosecond relaxation process.
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Affiliation(s)
- Brantley A West
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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19
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Billinghurst BE, Oladepo SA, Loppnow GR. Initial excited-state structural dynamics of thymine derivatives. J Phys Chem B 2012; 116:10496-503. [PMID: 22697627 DOI: 10.1021/jp301952v] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Thymine is one of the pyrimidine nucleobases found in DNA. Upon absorption of UV light, thymine forms a number of photoproducts, including the cyclobutyl photodimer, the pyrimidine pyrimidinone [6-4] photoproduct and the photohydrate. Here, we use UV resonance Raman spectroscopy to measure the initial excited-state structural dynamics of the N(1)-substituted thymine derivatives N(1)-methylthymine, thymidine, and thymidine 5'-monophosphate in an effort to understand the role of the N1 substituent in determining the excited-state structural dynamics and the subsequent photochemistry. The UV resonance Raman spectrum of thymidine and thymidine 5'-monophosphate are similar to that of thymine, suggesting that large masses at N(1) effectively isolate the vibrations of the nucleobase. However, the UV resonance Raman spectrum of N(1)-methylthymine is significantly different, suggesting that the methyl group couples into the thymine ring vibrations. The resulting resonance Raman intensities and absorption spectra are self-consistently simulated with a time-dependent expression to quantitatively extract the initial excited-state slopes, homogeneous and inhomogeneous linewidths, and electronic parameters. These results are discussed in the context of the known photochemistry of thymine and its derivatives.
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Affiliation(s)
- Brant E Billinghurst
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada
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20
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Kobayashi T, Kida Y. Ultrafast spectroscopy with sub-10 fs deep-ultraviolet pulses. Phys Chem Chem Phys 2012; 14:6200-10. [PMID: 22354017 DOI: 10.1039/c2cp23649d] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Time-resolved transient absorption spectroscopy with sub-9 fs ultrashort laser pulses in the deep-ultraviolet (DUV) region is reported for the first time. Single 8.7 fs DUV pulses with a spectral range of 255-290 nm are generated by a chirped-pulse four-wave mixing technique for use as pump and probe pulses. Electronic excited state and vibrational dynamics are simultaneously observed for an aqueous solution of thymine over the full spectral range using a 128-channel lock-in detector. Vibrational modes of the electronic ground state and excited states can be observed as well as the decay dynamics of the electronic excited state. Information on the initial phase of the vibrational modes is extracted from the measured difference absorbance trace, which contains oscillatory structures arising from the vibrational modes of the molecule. Along with other techniques such as time-resolved infrared spectroscopy, spectroscopy with sub-9 fs DUV pulses is expected to contribute to a detailed understanding of the photochemical dynamics of biologically significant molecules that absorb in the DUV region such as DNA and amino acids.
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Affiliation(s)
- Takayoshi Kobayashi
- Advanced Ultrafast Laser Research Center, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan.
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21
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Excited-state deactivation of the monohydrated complexes of cytosine, uracil, and thymine through S0/S1 conical intersections. MONATSHEFTE FUR CHEMIE 2012. [DOI: 10.1007/s00706-012-0720-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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22
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Sui XX, Li L, Zhao Y, Wang HG, Pei KM, Zheng X. Resonance Raman and density functional study of the excited state structural dynamics of 3-amino-2-cyclohexen-1-one in water and acetonitrile solvents. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2012; 85:165-172. [PMID: 22032972 DOI: 10.1016/j.saa.2011.09.055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 09/27/2011] [Indexed: 05/31/2023]
Abstract
FT-Raman and/or FT-IR spectra of 3-amino-2-cyclohexen-1-one (ACyO) in solid state and/or in solvents of water and acetonitrile were obtained. Density functional theory calculations were done to help elucidate the vibrational band assignments. The A-band resonance Raman spectra of ACyO were acquired in water and acetonitrile solvents to examine the excited state structural dynamics and the state-mixing or curve-crossing tuned by solvents. A preliminary resonance Raman intensity analysis using the time-dependent wave-packet theory and simple model was done for ACyO in acetonitrile solvent. Resonance Raman spectroscopic probing of the excited state curve-crossing or state-mixing was proposed.
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Affiliation(s)
- Xiao-Xian Sui
- Department of Chemistry and Key Lab. of Advanced Textiles Material and Manufacture Technology, MOE, Zhejiang Sci-Tech University, Hangzhou, PR China
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23
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West BA, Womick JM, Moran AM. Influence of temperature on thymine-to-solvent vibrational energy transfer. J Chem Phys 2011; 135:114505. [DOI: 10.1063/1.3628451] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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West BA, Womick JM, Moran AM. Probing ultrafast dynamics in adenine with mid-UV four-wave mixing spectroscopies. J Phys Chem A 2011; 115:8630-7. [PMID: 21756005 DOI: 10.1021/jp204416m] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Heterodyne-detected transient grating (TG) and two-dimensional photon echo (2DPE) spectroscopies are extended to the mid-UV spectral range in this investigation of photoinduced relaxation processes of adenine in aqueous solution. These experiments are the first to combine a new method for generating 25 fs laser pulses (at 263 nm) with the passive phase stability afforded by diffractive optics-based interferometry. We establish a set of conditions (e.g., laser power density, solute concentration) appropriate for the study of dynamics involving the neutral solute. Undesired solute photoionization is shown to take hold at higher peak powers of the laser pulses. Signatures of internal conversion and vibrational cooling dynamics are examined using TG measurements with signal-to-noise ratios as high as 350 at short delay times. In addition, 2DPE line shapes reveal correlations between excitation and emission frequencies in adenine, which reflect electronic and nuclear relaxation processes associated with particular tautomers. Overall, this study demonstrates the feasibility of techniques that will hold many advantages for the study of biomolecules whose lowest-energy electronic resonances are found in the mid-UV (e.g., DNA bases, amino acids).
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Affiliation(s)
- Brantley A West
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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25
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Kim NJ, Chang J, Kim HM, Kang H, Ahn TK, Heo J, Kim SK. Femtosecond Decay Dynamics of Intact Adenine and Thymine Base Pairs in a Supersonic Jet. Chemphyschem 2011; 12:1935-9. [DOI: 10.1002/cphc.201100091] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 04/04/2011] [Indexed: 11/06/2022]
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26
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Yang YL, Dyakov Y, Lee YT, Ni CK, Sun YL, Hu WP. Photodissociation dynamics of hydroxybenzoic acids. J Chem Phys 2011; 134:034314. [DOI: 10.1063/1.3526059] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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27
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Delchev VB. Photoinduced conformational transformation of the hydroxy form of uridine and deoxyuridine and hydrogen detachment in oxo and hydroxy tautomers of the compounds: a computational study. MONATSHEFTE FUR CHEMIE 2010. [DOI: 10.1007/s00706-010-0385-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Szymczak JJ, Müller T, Lischka H. The effect of hydration on the photo-deactivation pathways of 4-aminopyrimidine. Chem Phys 2010. [DOI: 10.1016/j.chemphys.2010.07.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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29
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Tseng CM, Lin MF, Yang YL, Ho YC, Ni CK, Chang JL. Photostability of amino acids: photodissociation dynamics of phenylalanine chromophores. Phys Chem Chem Phys 2010; 12:4989-95. [DOI: 10.1039/b925338f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Tseng CH, Matsika S, Weinacht TC. Two-dimensional ultrafast fourier transform spectroscopy in the deep ultraviolet. OPTICS EXPRESS 2009; 17:18788-18793. [PMID: 20372612 DOI: 10.1364/oe.17.018788] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We demonstrate two-dimensional ultrafast fourier transform spectroscopy in the deep ultraviolet (approximately 260 nm) using an acousto-optic modulator based pulse shaper. The use of a pulse shaper in the ultraviolet allows for rapid scanning, high phase (time) stability (approximately 0.017 rad) and phase cycling. We present measurements on the DNA nucleobase Adenine.
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Affiliation(s)
- Chien-hung Tseng
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794-3800, USA
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31
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Karunakaran V, Kleinermanns K, Improta R, Kovalenko SA. Photoinduced dynamics of guanosine monophosphate in water from broad-band transient absorption spectroscopy and quantum-chemical calculations. J Am Chem Soc 2009; 131:5839-50. [PMID: 19341282 DOI: 10.1021/ja810092k] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Guanosine monophosphate (GMP) in aqueous solutions has been studied with femtosecond broad-band transient absorption spectroscopy and by quantum-mechanical calculations. The sample was excited at 267 or 287 nm and probed between 270 and 1000 nm with 100 fs resolution, for various pH values between 2 and 7. At pH 2, when the guanine ring is ground-state protonated (GMPH(+)), we observe isosbestic behavior indicating state-to-state relaxation. The relaxation is biexponential, tau(1) = 0.4 ps, tau(2) = 2.2 ps, and followed by slower internal conversion with tau(3) = 167 ps. For nonprotonated GMP in the pH range 7-4, we find biexponential decay in the region 400-900 nm (tau(1) = 0.22 ps, tau(2) = 0.9 ps), whereas, between 270 and 400 nm, the behavior is triexponential with one growing, tau(1) = 0.25 ps, and two decaying, tau(2) = 1.0 ps, tau(3) = 2.5 ps, components. The excited-state evolution is interpreted with the help of quantum-chemical calculations, performed at the time-dependent PBE0 level accounting for bulk solvent effects and specific solvation. The computed dynamics involves L(a) and L(b) bright excited states, whereas the n(0)pi* and pisigma* dark excited states play a minor role. Independent of the pH, the photoinduced evolution involves ultrafast L(b)-->L(a) conversion (tau(ba) << 100 fs) and exhibits the presence of a wide planar plateau on L(a). For neutral GMP a barrierless path connects this region to a conical intersection (CI) with the ground state, giving an account of the ultrafast decay of this species. For protonated GMPH(+) the system evolves into a stable minimum L(a min) characterized by out-of-plane displacement of NH and CH groups, which explains the longer (167 ps) fluorescence lifetime.
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Affiliation(s)
- Venugopal Karunakaran
- Department of Chemistry, Humboldt University, Brook-Taylor Street-2, D-12489 Berlin, Germany
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32
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Zhu XM, Wang HG, Zheng X, Phillips DL. Role of Ribose in the Initial Excited State Structural Dynamics of Thymidine in Water Solution: A Resonance Raman and Density Functional Theory Investigation. J Phys Chem B 2008; 112:15828-36. [DOI: 10.1021/jp806248b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xin-Ming Zhu
- Department of Chemistry and State Key Laboratory of ATMMT(MOE), Zhejiang Sci-Tech University, Hangzhou, People’s Republic of China 310018, and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, People’s Republic of China
| | - Hui-gang Wang
- Department of Chemistry and State Key Laboratory of ATMMT(MOE), Zhejiang Sci-Tech University, Hangzhou, People’s Republic of China 310018, and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, People’s Republic of China
| | - Xuming Zheng
- Department of Chemistry and State Key Laboratory of ATMMT(MOE), Zhejiang Sci-Tech University, Hangzhou, People’s Republic of China 310018, and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, People’s Republic of China
| | - David Lee Phillips
- Department of Chemistry and State Key Laboratory of ATMMT(MOE), Zhejiang Sci-Tech University, Hangzhou, People’s Republic of China 310018, and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, People’s Republic of China
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33
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Lin MF, Dyakov YA, Lee YT, Lin SH, Mebel AM, Ni CK. Photodissociation of S atom containing amino acid chromophores. J Chem Phys 2007; 127:064308. [PMID: 17705597 DOI: 10.1063/1.2761916] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Photodissociation of 3-(methylthio)propylamine and cysteamine, the chromophores of S atom containing amino acid methionine and cysteine, respectively, was studied separately in a molecular beam at 193 nm using multimass ion imaging techniques. Four dissociation channels were observed for 3-(methylthio)propylamine, including (1) CH(3)SCH(2)CH(2)CH(2)NH(2)-->CH(3)SCH(2)CH(2)CH(2)NH+H, (2) CH(3)SCH(2)CH(2)CH(2)NH(2)-->CH(3)+SCH(2)CH(2)CH(2)NH(2), (3) CH(3)SCH(2)CH(2)CH(2)NH(2)-->CH(3)S+CH(2)CH(2)CH(2)NH(2), and (4) CH(3)SCH(2)CH(2)CH(2)NH(2)-->CH(3)SCH(2)+CH(2)CH(2)NH(2). Two dissociation channels were observed from cysteamine, including (5) HSCH(2)CH(2)NH(2)-->HS+CH(2)CH(2)NH(2) and (6) HSCH(2)CH(2)NH(2)-->HSCH(2)+CH(2)NH(2). The photofragment translational energy distributions suggest that reaction (1) and parts of the reactions (2), (3), (5) occur on the repulsive excited states. However, reaction (4), (6) occur only after the internal conversion to the electronic ground state. Since the dissociation from an excited state with a repulsive potential energy surface is very fast, it would not be quenched completely even in the condensed phase. Our results indicate that reactions following dissociation may play an important role in the UV photochemistry of S atom containing amino acid chromophores in the condensed phase. A comparison with the potential energy surface from ab initio calculations and branching ratios from RRKM calculations was made.
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Affiliation(s)
- Ming-Fu Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
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34
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Tseng CM, Lee YT, Ni CK, Chang JL. Photodissociation dynamics of the chromophores of the amino acid tyrosine: p-methylphenol, p-ethylphenol, and p-(2-aminoethyl)phenol. J Phys Chem A 2007; 111:6674-8. [PMID: 17447739 DOI: 10.1021/jp068968q] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photodissociation of p-methylphenol, p-ethylphenol, and p-(2-aminoethyl)phenol, chromophores of the amino acid tyrosine, was studied separately for each compound in a molecular beam at 248 nm using multimass ion imaging techniques. They show interesting side-chain size-dependent dissociation properties. Only one dissociation channel, that is, H atom elimination, was observed for both p-methylphenol and p-ethylphenol. The photofragment translational energy distributions and potential energy surfaces from ab initio calculation suggest that H atom elimination occurs from a repulsive excited state. On the other hand, the H atom elimination channel is quenched completely by internal conversion and/or intersystem crossing in p-(2-aminoethyl)phenol. Only C-C bond cleavage was observed from p-(2-aminoethyl)phenol. The photofragment translational energy distribution shows a slow component and a fast component. The fast component results from dissociation on an electronic excited state, but the slow component occurs only after the internal conversion to the ground electronic state. Comparison with the photodissociation of phenol and ethylbenzene is made.
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Affiliation(s)
- Chien-Ming Tseng
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, 10617 Taiwan
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35
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Noguera M, Blancafort L, Sodupe M, Bertran J. Canonical Watson–Crick base pair interactions in π → π* type triplet states. Mol Phys 2007. [DOI: 10.1080/00268970500418349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- M Noguera
- a Universitat Autònoma de Barcelona , Spain
| | | | - M Sodupe
- a Universitat Autònoma de Barcelona , Spain
| | - J Bertran
- a Universitat Autònoma de Barcelona , Spain
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36
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Panajotović R, Michaud M, Sanche L. Cross sections for low-energy electron scattering from adenine in the condensed phase. Phys Chem Chem Phys 2006; 9:138-48. [PMID: 17164896 DOI: 10.1039/b612700b] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Measurements of the vibrational and electronic excitation of a sub-monolayer up to a monolayer film of adenine were performed with a high resolution electron energy-loss (HREEL) spectrometer. The integral cross sections (over the half-space angle) for excitation of the normal vibrational modes of the ground electronic state and electronically excited states are calculated from the measured reflectivity EEL spectra. Most cross sections for vibrational excitation are of the order of 10(-17) cm(2), the largest being the out-of-plane wagging of the amino-group and the six-member ring deformations. A wide resonance feature appears in the incident energy dependence of the vibrational cross sections at 3-5 eV, while a weak shoulder is present in this dependence for combined ring deformations and bending of hydrogen atoms. For the five excited electronic states, at 4.7, 5.0, 5.5, 6.1 and 6.6 eV, the cross sections are of the order of 10(-18) cm(2), except in the case of the state at the energy of 6.1 eV, for which it is two to three times higher.
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Affiliation(s)
- Radmila Panajotović
- Groupe en sciences des radiations, Département de médecine nucléaire et de radiobiologie, Faculté de médecine, Université de Sherbrooke, 3001, 12e Av. Nord, Sherbrooke (Québec), Canada.
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37
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Abstract
An ab initio theoretical study at the CASPT2 level is reported on minimum energy reaction paths, state minima, transition states, reaction barriers, and conical intersections on the potential energy hypersurfaces of two tautomers of adenine: 9H- and 7H-adenine. The obtained results led to a complete interpretation of the photophysics of adenine and derivatives, both under jet-cooled conditions and in solution, within a three-state model. The ultrafast subpicosecond fluorescence decay measured in adenine is attributed to the low-lying conical intersection (gs/pipi* La)(CI), reached from the initially populated 1(pipi* La) state along a path which is found to be barrierless only in 9H-adenine, while for the 7H tautomer the presence of an intermediate plateau corresponding to an NH2-twisted conformation may explain the absence of ultrafast decay in 7-substituted compounds. A secondary picosecond decay is assigned to a path involving switches towards two other states, 1(pipi* Lb) and 1(npi*), ultimately leading to another conical intersection with the ground state, (gs/npi*), with a perpendicular disposition of the amino group. The topology of the hypersurfaces and the state properties explain the absence of secondary decay in 9-substituted adenines in water in terms of the higher position of the 1(npi*) state and also that the 1(pipi* Lb) state of 7H-adenine is responsible for the observed fluorescence in water. A detailed discussion comparing recent experimental and theoretical findings is given. As for other nucleobases, the predominant role of a pipi*-type state in the ultrafast deactivation of adenine is confirmed.
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Affiliation(s)
- Luis Serrano-Andrés
- Instituto de Ciencia Molecular, Universitat de València, Dr. Moliner 50, Burjassot, 46100 Valencia, Spain.
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38
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Canuel C, Mons M, Piuzzi F, Tardivel B, Dimicoli I, Elhanine M. Excited states dynamics of DNA and RNA bases: characterization of a stepwise deactivation pathway in the gas phase. J Chem Phys 2006; 122:074316. [PMID: 15743241 DOI: 10.1063/1.1850469] [Citation(s) in RCA: 334] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Radiationless deactivation pathways of excited gas phase nucleobases were investigated using mass-selected femtosecond resolved pump-probe resonant ionization. By comparison between nucleobases and methylated species, in which tautomerism cannot occur, we can access intrinsic mechanisms at a time resolution never reported so far (80 fs). At this time resolution, and using appropriate substitution, real nuclear motion corresponding to active vibrational modes along deactivation coordinates can actually be probed. We provide evidence for the existence of a two-step decay mechanism, following a 267 nm excitation of the nucleobases. The time resolution achieved together with a careful zero time-delay calibration between lasers allow us to show that the first step does correspond to intrinsic dynamics rather than to a laser cross correlation. For adenine and 9-methyladenine a first decay component of about 100 fs has been measured. This first step is radically increased to 200 fs when the amino group hydrogen atoms of adenine are substituted by methyl groups. Our results could be rationalized according to the effect of the highly localized nature of the excitation combined to the presence of efficient deactivation pathway along both pyrimidine ring and amino group out-of-plane vibrational modes. These nuclear motions play a key role in the vibronic coupling between the initially excited pipi* and the dark npi* states. This seems to be the common mechanism that opens up the earlier phase of the internal conversion pathway which then, in consideration of the rather fast relaxation times observed, would probably proceed via conical intersection between the npi* relay state and high vibrational levels of the ground state.
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Affiliation(s)
- Clélia Canuel
- Laboratoire Francis Perrin, CNRS URA 2453, DRECAM-SPAM, CEA Saclay, 91191 Gif-sur-Yvette, France
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39
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Lin MF, Tseng CM, Lee YT, Ni CK. Photodissociation dynamics of indole in a molecular beam. J Chem Phys 2005; 123:124303. [PMID: 16392478 DOI: 10.1063/1.2009736] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Photodissociation of indole at 193 and 248 nm under collision-free conditions has been studied in separate experiments using multimass ion imaging techniques. H atom elimination was found to be the only dissociation channel at both wavelengths. The photofragment translational energy distribution obtained at 193 nm contains a fast and a slow component. Fifty-four percent of indole following the 193 nm photoexcitation dissociate from electronically excited state, resulting in the fast component. The rest of 46% indole dissociate through the ground electronic state, giving rise to the slow component. A dissociation rate of 6 x 10(5) s(-1), corresponding to the dissociation from the ground electronic state, was determined. Similar two-component translational energy distribution was observed at 248 nm. However, more than 80% of indole dissociate from electronically excited state after the absorption of 248 nm photons. A comparison with the potential energy surfaces from the ab initio calculation has been made.
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Affiliation(s)
- Ming-Fu Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10617, Taiwan
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40
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Crespo-Hernández CE, Cohen B, Hare PM, Kohler B. Ultrafast Excited-State Dynamics in Nucleic Acids. Chem Rev 2004; 104:1977-2019. [PMID: 15080719 DOI: 10.1021/cr0206770] [Citation(s) in RCA: 962] [Impact Index Per Article: 48.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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41
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Doltsinis NL. Excited state proton transfer and internal conversion ino-hydroxybenzaldehyde: new insights from non-adiabaticab initiomolecular dynamics. Mol Phys 2004. [DOI: 10.1080/00268970410001668408] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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42
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He Y, Wu C, Kong W. Photophysics of Methyl-Substituted Uracils and Thymines and Their Water Complexes in the Gas Phase. J Phys Chem A 2004. [DOI: 10.1021/jp036553o] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yonggang He
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003
| | - Chengyin Wu
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003
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43
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Cohen B, Crespo-Hernández CE, Kohler B. Strickler–Berg analysis of excited singlet state dynamics in DNA and RNA nucleosides. Faraday Discuss 2004; 127:137-47. [PMID: 15471343 DOI: 10.1039/b316939a] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The excited singlet state lifetime of the ribonucleoside uridine was found to be 210+/-30 fs by femtosecond transient absorption spectroscopy. This value is considerably shorter than all previous time-domain measurements. This result and our previous lifetime measurements [see J.-M. L. Pecourt, J. Peon and B. Kohler, J. Am. Chem. Soc., 2001, 123, 10 370] for the other common nucleosides are compared with lifetimes calculated from available photophysical data using the Strickler-Berg (SB) equation. The calculated lifetimes for pyrimidine nucleosides are 10-25% lower than the lifetimes measured in femtosecond transient absorption experiments. For the purine nucleosides, guanosine and adenosine, consideration of just the lowest 1pi --> pi* transition led to predicted lifetimes that are three times greater than experimental ones. On the other hand, inclusion of both of the lowest energy 1pi --> pi* absorption bands in the SB equation resulted in much better agreement with the experimental values. This suggests that both 1pi pi* states of the purine nucleosides contribute to their emission. Decay by the bright 1pi pi* state (or states, in the case of the purines) is believed to be responsible for the experimentally observed lifetimes.
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Affiliation(s)
- Boiko Cohen
- Department of Chemistry, The Ohio State University, Columbus, Ohio 43214, USA
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44
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Sobolewski AL, Domcke W. Ab initio studies on the photophysics of the guanine–cytosine base pair. Phys Chem Chem Phys 2004. [DOI: 10.1039/b314419d] [Citation(s) in RCA: 257] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Cytosine excited state dynamics studied by femtosecond fluorescence upconversion and transient absorption spectroscopy. Chem Phys Lett 2003. [DOI: 10.1016/j.cplett.2003.09.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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46
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Pedersen DB, Zgierski MZ, Simard B. Dehydrogenation and Other Non-radiative Relaxation Processes in Gas-Phase Metal−DNA Base Complexes. J Phys Chem A 2003. [DOI: 10.1021/jp034804n] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- David B. Pedersen
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada, K1A 0R6
| | - Marek Z. Zgierski
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada, K1A 0R6
| | - Benoit Simard
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada, K1A 0R6
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He Y, Wu C, Kong W. Decay Pathways of Thymine and Methyl-Substituted Uracil and Thymine in the Gas Phase. J Phys Chem A 2003. [DOI: 10.1021/jp034733s] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yonggang He
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003
| | - Chengyin Wu
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003
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Kang H, Lee KT, Jung B, Ko YJ, Kim SK. Intrinsic lifetimes of the excited state of DNA and RNA bases. J Am Chem Soc 2002; 124:12958-9. [PMID: 12405817 DOI: 10.1021/ja027627x] [Citation(s) in RCA: 292] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The lifetimes of the excited state of free nucleobases were measured in the gas phase for the first time. They are, respectively, 1.0 and 0.8 ps for the purine bases adenine (shown above) and guanine and 3.2, 2.4, and 6.4 ps for the pyrimidine bases cytosine, uracil, and thymine at 267 nm. The longer lifetimes of the pyrimidine bases may be associated with their higher propensity toward photodegradation, especially in the case of thymine. The ultrashort lifetime of nucleobases conventionally known in solution was found to be an intrinsic molecular property due to extremely facile internal conversion, and therefore the lifetime should be largely independent of the medium at this energy, that is, whether in vacuo, in solution, or in vivo. The evolutionary selection of nucleobases as the durable carriers of genetic information is suggested to be due to their inherent immunity from photochemical reactions.
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Affiliation(s)
- Hyuk Kang
- School of Chemistry, Seoul National University, Seoul 151-747, Korea
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