1
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Zhao T, Matthews DA. Analytic Gradients for Equation-of-Motion Coupled Cluster with Single, Double, and Perturbative Triple Excitations. J Chem Theory Comput 2024. [PMID: 39214857 DOI: 10.1021/acs.jctc.4c00752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Understanding the process of molecular photoexcitation is crucial in various fields, including drug development, materials science, photovoltaics, and more. The electronic vertical excitation energy is a critical property, for example in determining the singlet-triplet gap of chromophores. However, a full understanding of excited-state processes requires additional explorations of the excited-state potential energy surface and electronic properties, which is greatly aided by the availability of analytic energy gradients. Owing to its robust high accuracy over a wide range of chemical problems, equation-of-motion coupled cluster with single and double excitations (EOM-CCSD) is a powerful method for predicting excited-state properties, and the implementation of analytic gradients of many EOM-CCSD variants (excitation energies, ionization potentials, electron attachment energies, etc.) along with numerous successful applications highlights the flexibility of the method. In specific cases where a higher level of accuracy is needed or in more complex electronic structures, the inclusion of triple excitations becomes essential, for example, in the EOM-CCSD* approach of Saeh and Stanton. In this work, we derive and implement for the first time the analytic gradients of EOMEE-CCSD*, which also provides a template for analytic gradients of related excited-state methods with perturbative triple excitations. The capabilities of analytic EOMEE-CCSD* gradients are illustrated by several representative examples.
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Affiliation(s)
- Tingting Zhao
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75205, United States
| | - Devin A Matthews
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75205, United States
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2
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Sadiq S, Park W, Mironov V, Lee S, Filatov Gulak M, Choi CH. Prototropically Controlled Dynamics of Cytosine Photodecay. J Phys Chem Lett 2023; 14:791-797. [PMID: 36652675 DOI: 10.1021/acs.jpclett.2c03340] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The effect of the existence of several prototropic tautomers of cytosine on its UV/vis spectra and the excited state decay dynamics is studied by spectral and nonadiabatic molecular dynamics (NAMD) simulations in connection with the mixed-reference spin-flip time-dependent density functional theory (MRSF-TDDFT) method. Simulated UV/vis spectra provide a strong indication that the H3N keto-amino cytosine tautomer (the least anticipated species) may be present under experimental conditions. The NAMD simulations yield a wide range of excited state decay constants for various tautomers of cytosine, ranging from ∼1.3 ps for the biologically relevant H1N keto-amino tautomer to ∼0.1 ps for the keto-imino tautomer. The slowness of the H1N decay dynamics follows from the presence of a barrier on the excited state energy surface separating the Franck-Condon structure from the major decay funnel, the conical intersection seam. It is suggested that the experimentally observed photodecay dynamics may result from a combination of the decay processes of various tautomers (H3N in particular) present simultaneously under the experimental conditions.
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Affiliation(s)
- Saima Sadiq
- Department of Chemistry, Kyungpook National University, Daegu41566, South Korea
| | - Woojin Park
- Department of Chemistry, Kyungpook National University, Daegu41566, South Korea
| | - Vladimir Mironov
- Department of Chemistry, Kyungpook National University, Daegu41566, South Korea
| | - Seunghoon Lee
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California91125, United States
| | | | - Cheol Ho Choi
- Department of Chemistry, Kyungpook National University, Daegu41566, South Korea
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3
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Wu P, Wang X, Pan H, Chen J. Direct Observation of Excitation Wavelength-Dependent Ultrafast Intersystem Crossing in Cytosine Nucleoside Solution. J Phys Chem B 2022; 126:7975-7980. [PMID: 36179273 DOI: 10.1021/acs.jpcb.2c05865] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A triplet excited state can lead to different DNA photolesions, especially in cytosine and its nucleoside/nucleotide as they are hotspots for DNA mutations. However, the triplet state generation mechanism is in controversy, and experimental evidence of ultrafast intersystem crossing (ISC) has not been registered in these molecules. In this work, ultrafast ISC is directly observed in 2'-deoxycytidine (dCyd) solution by using femtosecond transient absorption spectroscopy. Surprisingly, we demonstrate that ISC in dCyd is sensitive to the excitation wavelength, and a spin-vibronic ISC mechanism is proposed. This finding is the last piece of the dCyd excited-state deactivation mechanism puzzle and sets the base for further investigation of triplet state-involved photophysics and photochemistry in dCyd-containing DNA.
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Affiliation(s)
- Peicong Wu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Xueli Wang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Haifeng Pan
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Jinquan Chen
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
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4
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Ho J, Cheng P. Ultrafast excited‐state dynamics of gas‐phase 5‐methylcytosine tautomers. J CHIN CHEM SOC-TAIP 2021. [DOI: 10.1002/jccs.202100254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jr‐Wei Ho
- Department of Chemistry National Tsing Hua University Hsinchu Taiwan
| | - Po‐Yuan Cheng
- Department of Chemistry National Tsing Hua University Hsinchu Taiwan
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5
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Yaghoubi Jouybari M, Liu Y, Improta R, Santoro F. Ultrafast Dynamics of the Two Lowest Bright Excited States of Cytosine and 1-Methylcytosine: A Quantum Dynamical Study. J Chem Theory Comput 2020; 16:5792-5808. [PMID: 32687360 DOI: 10.1021/acs.jctc.0c00455] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The nonadiabatic quantum dynamics (QD) of cytosine and 1-methylcytosine in the gas phase is simulated for 250 fs after a photoexcitation to one of the first two bright states. The nuclear wavepacket is propagated on the coupled diabatic potential energy surfaces of the lowest seven excited states, including ππ*, nπ*, and Rydberg states along all the vibrational degrees of freedom. We focus in particular on the interplay between the bright and the dark nπ* states, not considering the decay to the ground electronic state. To run these simulations, we implemented an automatic general procedure to parametrize linear vibronic coupling (LVC) models with time-dependent density functional theory (DFT) computations and interfaced it with Gaussian package. The wavepacket was propagated with the multilayer version of the multiconfigurational time dependent Hartree method. Two different density functionals, PBE0 and CAM-B3LYP, which provide a different description of the relative stability of the lowest energy dark states, were used to parametrize the LVC Hamiltonian. Part of the photoexcited population on lowest HOMO-LUMO transition (πHπL*) decays within less than 100 fs to a nπ* state which mainly involves a promotion of an electron from the oxygen lone pair to the LUMO (nOπL*). The population of the second ππ* state decays almost completely, in <100 fs, not only to πHπL* and to nOπL* states but also to another nπL* state involving the nitrogen lone pair. The efficiency of the adopted protocol allowed us to check the accuracy of the predictions by repeating the QD simulations with different LVC Hamiltonians parametrized either at the ground-state minimum or at stationary structures of different relevant excited states.
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Affiliation(s)
- Martha Yaghoubi Jouybari
- CNR-Consiglio Nazionale delle Ricerche, Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR), SS di Pisa, Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa, Italy
| | - Yanli Liu
- School of Physics and Optoelectronics Engineering, Ludong University, 264025 Yantai, Shandong, PR China
| | - Roberto Improta
- CNR-Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini (IBB-CNR), via Mezzocannone 16, I-80136 Napoli, Italy
| | - Fabrizio Santoro
- CNR-Consiglio Nazionale delle Ricerche, Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR), SS di Pisa, Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa, Italy
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6
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Trachsel MA, Blaser S, Lobsiger S, Siffert L, Frey HM, Blancafort L, Leutwyler S. Locating Cytosine Conical Intersections by Laser Experiments and Ab Initio Calculations. J Phys Chem Lett 2020; 11:3203-3210. [PMID: 32251591 DOI: 10.1021/acs.jpclett.0c00779] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The decay mechanism of S0 → S1 excited cytosine (Cyt) and the effect of substitution are studied combining jet-cooled spectroscopy (nanosecond resonant two-photon ionization (R2PI) and picosecond lifetime measurements) with CASPT2//CASSCF computations for eight derivatives. For Cyt and five derivatives substituted at N1, C5, and C6, rapid internal conversion sets in at 250-1200 cm-1 above the 000 bands. The break-off in the spectra correlates with the calculated barriers toward the "C5-C6 twist" conical intersection, which unambiguously establishes the decay mechanism at low S1 state vibrational energies. The barriers increase with substituents that stabilize the charge shifts at C4, C5, and C6 following (1ππ*) excitation. The R2PI spectra of the clamped derivatives 5,6-trimethyleneCyt (TMCyt) and 1-methyl-TMCyt (1M-TMCyt), which decay along an N3 out-of-plane coordinate, extend up to +3500 and +4500 cm-1.
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Affiliation(s)
- Maria A Trachsel
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Susan Blaser
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Simon Lobsiger
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Luca Siffert
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Hans-Martin Frey
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Lluís Blancafort
- Institut de Quı́mica Computacional i Catàlisi and Departament de Quı́mica, Universitat de Girona, C/M.A. Capmany 69, 17003 Girona, Spain
| | - Samuel Leutwyler
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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7
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Sapunar M, Domcke W, Došlić N. UV absorption spectra of DNA bases in the 350-190 nm range: assignment and state specific analysis of solvation effects. Phys Chem Chem Phys 2019; 21:22782-22793. [PMID: 31595896 DOI: 10.1039/c9cp04662c] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The theoretical assignment of electronic spectra of polyatomic molecules is a challenging problem that requires the specification of the character of a large number of electronic states. We propose a procedure for automatically determining the character of electronic transitions and apply it to the study of UV spectra of DNA bases in the gas phase and in the aqueous environment. The procedure is based on the computation of electronic wave function overlaps and accounts for an extensive sampling of nuclear geometries. Novelties of this work are the theoretical assignment of the electronic spectra of DNA bases up to 190 nm and a state specific analysis of solvation effects. By accounting for different effects contributing to the total solvent shift we obtained a good agreement between the computed and experimental spectra. Effects of vibrational averaging, temperature and solvent-induced structural changes shift excitation energies to lower values. Solvent-solute electrostatic interactions are state specific and strongly destabilize nRyd states, and to lesser extent nπ* and πRyd states. Altogether, this results in the stabilization of ππ* states and destabilization of nπ*, πRyd and nRyd states in solution.
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Affiliation(s)
- Marin Sapunar
- Department of Physical Chemistry, Ruder Bošković Institute, 10000 Zagreb, Croatia.
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8
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Nowak MJ, Reva I, Lopes Jesus AJ, Lapinski L, Fausto R. UV-promoted radical formation, and near-IR-induced and spontaneous conformational isomerization in monomeric 9-methylguanine isolated in low-temperature Ar matrices. Phys Chem Chem Phys 2019; 21:22857-22868. [PMID: 31599896 DOI: 10.1039/c9cp04487f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three low-energy isomers of 9-methylguanine, the amino-oxo (AO) form and two amino-hydroxy (AH1 and AH2) conformers, were trapped from the gas phase into low-temperature argon matrices. The AH1 and AH2 isomers, differing in the orientation of the OH group, were found to transform into each other upon excitation with near-IR light. The population of the AO form of the compound was not changed upon any near-IR irradiation of the matrix samples. Using monochromatic near-IR light, generated by a frequency-tunable laser source, it was possible to selectively induce the AH1 → AH2 or AH2 → AH1 conversion. Photoreversibility of this conformational transformation was then demonstrated. Exposure of matrix-isolated monomers of 9-methylguanine to broadband near-IR light also led to conformational conversions within the amino-hydroxy tautomeric form; the final stage of this process was always the same photostationary state independent of the initial ratio of AH1 and AH2 populations. Spontaneous conformational conversion, transforming the higher-energy AH2 form into the lower-energy AH1 isomer, was observed for matrix-isolated monomers of 9-methylguanine kept in the dark. The mechanism of this process must rely on quantum tunneling of the light hydrogen atom. Irradiation of matrix-isolated 9-methylguanine with UV laser light at λ = 288 or 285 nm led to a substantial consumption of the two AH forms, while the amount of AO isomer remained unchanged. On the other hand, a decrease in the population of the AO isomer occurred upon excitations at shorter wavelengths, λ = 280 or 275 nm. The spectral changes observed after UV-irradiation suggest the generation (and stabilization in the matrix) of a radical species, resulting from the photocleavage of the O-H or N1-H bonds, in the AH or AO isomer, respectively.
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Affiliation(s)
- Maciej J Nowak
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland.
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9
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Trachsel MA, Blaser S, Siffert L, Wiedmer T, Leutwyler S. Excited-state vibrations, lifetimes, and nonradiative dynamics of jet-cooled 1-ethylcytosine. J Chem Phys 2019; 151:124301. [PMID: 31575195 DOI: 10.1063/1.5116911] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The S1 excited-state lifetime of jet-cooled 1-ethylcytosine (1ECyt) is ∼1 ns, one of the longest lifetimes for cytosine derivatives to date. Here, we analyze its S0 → S1 vibronic spectrum using two-color resonant two-photon ionization and UV/UV holeburning spectroscopy. Compared to cytosine and 1-methylcytosine, the S0 → S1 spectrum of 1ECyt shows a progression in the out-of-plane "butterfly" mode ν1 ', identified by spin-component scaled-second-order coupled-cluster method ab initio calculations. We also report time-resolved S1 state nonradiative dynamics at ∼20 ps resolution by the pump/delayed ionization technique. The S1 lifetime increases with the number of ν1 ' quanta from τ = 930 ps at v1 '=0 to 1030 ps at v1 '=2, decreasing to 14 ps at 710 cm-1 vibrational energy. We measured the rate constants for S1 ⇝ S0 internal conversion and S1 ⇝ T1 intersystem crossing (ISC): At the v' = 0 level, kIC is 8 × 108 s-1 or three times smaller than 1-methylcytosine. The ISC rate constant from v' = 0 to the T1(3ππ*) state is kISC = 2.4 × 108 s-1, 10 times smaller than the ISC rate constants of cytosine, but similar to that of 1-methylcytosine. Based on the calculated S1(1ππ*) state radiative lifetime τrad = 12 ns, the fluorescence quantum yield of 1ECyt is Φfl ∼ 7% and the intersystem crossing yield is ΦISC ∼ 20%. We measured the adiabatic ionization energy of 1-ethylcytosine via excitation of the S1 state as 8.353 ± 0.008 eV, which is 0.38 eV lower than that of amino-keto cytosine. Measurement of the ionization energy of the long-lived T1(ππ*) state formed via ISC reveals that it lies 3.2-3.4 eV above the S0 ground state.
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Affiliation(s)
- Maria A Trachsel
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Susan Blaser
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Luca Siffert
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Timo Wiedmer
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Samuel Leutwyler
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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10
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Wei SC, Ho JW, Yen HC, Shi HQ, Cheng LH, Weng CN, Chou WK, Chiu CC, Cheng PY. Ultrafast Excited-State Dynamics of Hydrogen-Bonded Cytosine Microsolvated Clusters with Protic and Aprotic Polar Solvents. J Phys Chem A 2018; 122:9412-9425. [PMID: 30452255 DOI: 10.1021/acs.jpca.8b09526] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Microsolvation effects on the ultrafast excited-state deactivation dynamics of cytosine (Cy) were studied in hydrogen-bonded Cy clusters with protic and aprotic solvents using mass-resolved femtosecond pump-probe ionization spectroscopy. Two protic solvents, water (H2O) and methanol (MeOH), and one aprotic solvent, tetrahydrofuran (THF), were investigated, and transients of Cy·(H2O)1-6, Cy·(MeOH)1-3, and Cy·THF microsolvated clusters produced in supersonic expansions were measured. With the aid of electronic structure calculations, we assigned the observed dynamics to the low-energy isomers of various Cy clusters and discussed the microsolvation effect on the excited-state deactivation dynamics. With the protic solvents only the microsolvated clusters of Cy keto tautomer were observed. The observed decay time constants of Cy·(H2O) n are 0.5 ps for n = 1 and ∼0.2-0.25 ps for n = 2-6. For Cy·(MeOH) n clusters, the decay time constant for n = 1 cluster is similar to that of the Cy monohydrate, but for n = 2 and 3 the decays are about a factor of 2 slower than the corresponding microhydrates. With the aprotic solvent, THF, hydrogen-bonded complexes of both keto and enol tautomers are present in the beam. The keto-Cy·THF shows a decay similar to that of the keto-Cy monomer, whereas the enol-Cy·THF exhibits a 2-fold slower decay than the enol-Cy monomer, suggesting an increase in the barrier to excited-state deactivation upon binding of one THF molecule to the enol form of Cy.
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Affiliation(s)
- Shih-Chun Wei
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan 30043 , Republic of China
| | - Jr-Wei Ho
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan 30043 , Republic of China
| | - Hung-Chien Yen
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan 30043 , Republic of China
| | - Hui-Qi Shi
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan 30043 , Republic of China
| | - Li-Hao Cheng
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan 30043 , Republic of China
| | - Chih-Nan Weng
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan 30043 , Republic of China
| | - Wei-Kuang Chou
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan 30043 , Republic of China
| | - Chih-Chung Chiu
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan 30043 , Republic of China
| | - Po-Yuan Cheng
- Department of Chemistry , National Tsing Hua University , Hsinchu , Taiwan 30043 , Republic of China
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11
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Röttger K, Marroux HJB, Böhnke H, Morris DTJ, Voice AT, Temps F, Roberts GM, Orr-Ewing AJ. Probing the excited state relaxation dynamics of pyrimidine nucleosides in chloroform solution. Faraday Discuss 2018; 194:683-708. [PMID: 27711889 DOI: 10.1039/c6fd00068a] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Ultrafast transient electronic and vibrational absorption spectroscopy (TEAS and TVAS) of 2'-deoxy-cytidine (dC) and 2'-deoxy-thymidine (dT) dissolved in chloroform examines their excited-state dynamics and the recovery of ground electronic state molecules following absorption of ultraviolet light. The chloroform serves as a weakly interacting solvent, allowing comparisons to be drawn with prior experimental studies of the photodynamics of these nucleosides in the gas phase and in polar solvents such as water. The pyrimidine base nucleosides have some propensity to dimerize in aprotic solvents, but the monomer photochemistry can be resolved clearly and is the focus of this study. UV absorption at a wavelength of 260 nm excites a 1ππ* ← S0 transition, but prompt crossing of a significant fraction (50% in dC, 17% in dT) of the 1ππ* population into a nearby 1nπ* state is too fast for the experiments to resolve. The remaining flux on the 1ππ* state leaves the vertical Franck-Condon region and encounters a conical intersection with the ground electronic state of ethylenic twist character. In dC, the 1ππ* state decays to the ground state with a time constant of 1.1 ± 0.1 ps. The lifetime of the 1nπ* state is much longer in the canonical forms of both molecules: recovery of the ground state population from these states occurs with time constants of 18.6 ± 1.1 ps in amino-oxo dC and ∼114 ps in dT, indicating potential energy barriers to the 1nπ*/S0 conical intersections. The small fraction of the imino-oxo tautomer of dC present in solution has a longer-lived 1nπ* state with a lifetime for ground state recovery of 193 ± 55 ps. No evidence is found for photo-induced tautomerization of amino-oxo dC to the imino-oxo form, or for population of low lying triplet states of this nucleoside. In contrast, ∼8% of the UV-excited dT molecules access the long-lived T1 (3ππ*) state through the 1nπ* state. The primary influence of the solvent appears to be the degree to which it destabilizes the states of 1nπ* character, with consequences for the lifetimes of these states as well as the triplet state yields.
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Affiliation(s)
- Katharina Röttger
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK. and Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
| | - Hugo J B Marroux
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - Hendrik Böhnke
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
| | - David T J Morris
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - Angus T Voice
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - Friedrich Temps
- Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, D-24098 Kiel, Germany
| | - Gareth M Roberts
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
| | - Andrew J Orr-Ewing
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
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Trachsel MA, Lobsiger S, Schär T, Blancafort L, Leutwyler S. Planarizing cytosine: The S 1 state structure, vibrations, and nonradiative dynamics of jet-cooled 5,6-trimethylenecytosine. J Chem Phys 2018; 146:244308. [PMID: 28668059 DOI: 10.1063/1.4989465] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We measure the S0 → S1 spectrum and time-resolved S1 state nonradiative dynamics of the "clamped" cytosine derivative 5,6-trimethylenecytosine (TMCyt) in a supersonic jet, using two-color resonant two-photon ionization (R2PI), UV/UV holeburning, and ns time-resolved pump/delayed ionization. The experiments are complemented with spin-component scaled second-order approximate coupled cluster (SCS-CC2), time-dependent density functional theory, and multi-state second-order perturbation-theory (MS-CASPT2) ab initio calculations. While the R2PI spectrum of cytosine breaks off ∼500 cm-1 above its 000 band, that of TMCyt extends up to +4400 cm-1 higher, with over a hundred resolved vibronic bands. Thus, clamping the cytosine C5-C6 bond allows us to explore the S1 state vibrations and S0 → S1 geometry changes in detail. The TMCyt S1 state out-of-plane vibrations ν1', ν3', and ν5' lie below 420 cm-1, and the in-plane ν11', ν12', and ν23' vibrational fundamentals appear at 450, 470, and 944 cm-1. S0 → S1 vibronic simulations based on SCS-CC2 calculations agree well with experiment if the calculated ν1', ν3', and ν5' frequencies are reduced by a factor of 2-3. MS-CASPT2 calculations predict that the ethylene-type S1 ⇝ S0 conical intersection (CI) increases from +366 cm-1 in cytosine to >6000 cm-1 in TMCyt, explaining the long lifetime and extended S0 → S1 spectrum. The lowest-energy S1 ⇝ S0 CI of TMCyt is the "amino out-of-plane" (OPX) intersection, calculated at +4190 cm-1. The experimental S1 ⇝ S0 internal conversion rate constant at the S1(v'=0) level is kIC=0.98-2.2⋅108 s-1, which is ∼10 times smaller than in 1-methylcytosine and cytosine. The S1(v'=0) level relaxes into the T1(3ππ*) state by intersystem crossing with kISC=0.41-1.6⋅108 s-1. The T1 state energy is measured to lie 24 580±560 cm-1 above the S0 state. The S1(v'=0) lifetime is τ=2.9 ns, resulting in an estimated fluorescence quantum yield of Φfl=24%. Intense two-color R2PI spectra of the TMCyt amino-enol tautomers appear above 36 000 cm-1. A sharp S1 ionization threshold is observed for amino-keto TMCyt, yielding an adiabatic ionization energy of 8.114±0.002 eV.
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Affiliation(s)
- Maria A Trachsel
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Simon Lobsiger
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Tobias Schär
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Lluís Blancafort
- Institut de Química Computacional i Catàlisi and Departament de Química, Facultat de Ciències, Universitat de Girona, C/M. A. Campmany 69, 17003 Girona, Spain
| | - Samuel Leutwyler
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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13
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Welborn VV, Van Voorhis T. Non-radiative deactivation of cytosine derivatives at elevated temperature. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1457806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
| | - Troy Van Voorhis
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, MA, USA
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14
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Penfold TJ, Gindensperger E, Daniel C, Marian CM. Spin-Vibronic Mechanism for Intersystem Crossing. Chem Rev 2018; 118:6975-7025. [DOI: 10.1021/acs.chemrev.7b00617] [Citation(s) in RCA: 401] [Impact Index Per Article: 66.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Thomas J. Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon-Tyne NE1 7RU, United Kingdom
| | - Etienne Gindensperger
- Laboratoire de Chimie Quantique, Institut de Chimie UMR-7177, CNRS - Université de Strasbourg, 1 Rue Blaise Pascal 67008 Strasbourg, France
| | - Chantal Daniel
- Laboratoire de Chimie Quantique, Institut de Chimie UMR-7177, CNRS - Université de Strasbourg, 1 Rue Blaise Pascal 67008 Strasbourg, France
| | - Christel M. Marian
- Institut für Theoretische Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
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15
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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: 69] [Impact Index Per Article: 11.5] [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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16
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Abstract
The response of nucleobases to UV radiation depends on structure in subtle ways, as revealed by gas-phase experiments.
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Affiliation(s)
- Samuel Boldissar
- Department of Chemistry and Biochemistry University of California Santa Barbara
- USA
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17
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Berenbeim JA, Boldissar S, Siouri FM, Gate G, Haggmark MR, Aboulache B, Cohen T, de Vries MS. Excited-State Dynamics of Isocytosine: A Hybrid Case of Canonical Nucleobase Photodynamics. J Phys Chem Lett 2017; 8:5184-5189. [PMID: 28985073 DOI: 10.1021/acs.jpclett.7b02032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present resonant two-photon ionization (R2PI) spectra of isocytosine (isoC) and pump-probe results on two of its tautomers. IsoC is one of a handful of alternative bases that have been proposed in scenarios of prebiotic chemistry. It is structurally similar to both cytosine (C) and guanine (G). We compare the excited-state dynamics with the Watson-Crick (WC) C and G tautomeric forms. These results suggest that the excited-state dynamics of WC form of G may primarily depend on the heterocyclic substructure of the pyrimidine moiety, which is chemically identical to isoC. For WC isoC we find a single excited-state decay with a rate of ∼1010 s-1, while the enol form has multiple decay rates, the fastest of which is 7 times slower than for WC isoC. The excited-state dynamics of isoC exhibits striking similarities with that of G, more so than with the photodynamics of C.
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Affiliation(s)
- Jacob A Berenbeim
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106-9510, United States
| | - Samuel Boldissar
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106-9510, United States
| | - Faady M Siouri
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106-9510, United States
| | - Gregory Gate
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106-9510, United States
| | - Michael R Haggmark
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106-9510, United States
| | - Briana Aboulache
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106-9510, United States
| | - Trevor Cohen
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106-9510, United States
| | - Mattanjah S de Vries
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106-9510, United States
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18
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Martínez-Fernández L, Pepino AJ, Segarra-Martí J, Jovaišaitė J, Vaya I, Nenov A, Markovitsi D, Gustavsson T, Banyasz A, Garavelli M, Improta R. Photophysics of Deoxycytidine and 5-Methyldeoxycytidine in Solution: A Comprehensive Picture by Quantum Mechanical Calculations and Femtosecond Fluorescence Spectroscopy. J Am Chem Soc 2017; 139:7780-7791. [DOI: 10.1021/jacs.7b01145] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- L. Martínez-Fernández
- Istituto di Biostrutture e Bioimmagini,
CNR, Via Mezzocannone 16, I-80134 Napoli, Italy
| | - A. J. Pepino
- Dipartimento di Chimica Industriale “T. Montanari”, Università di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy
| | - J. Segarra-Martí
- Laboratoire de Chimie UMR 5182, Univ Lyon, ENS de Lyon, CNRS, Université Lyon 1, F-69342 Lyon, France
| | - J. Jovaišaitė
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - I. Vaya
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - A. Nenov
- Dipartimento di Chimica Industriale “T. Montanari”, Università di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy
| | - D. Markovitsi
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - T. Gustavsson
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - A. Banyasz
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - M. Garavelli
- Dipartimento di Chimica Industriale “T. Montanari”, Università di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy
| | - R. Improta
- Istituto di Biostrutture e Bioimmagini,
CNR, Via Mezzocannone 16, I-80134 Napoli, Italy
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
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19
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Mavros MG, Hait D, Van Voorhis T. Condensed phase electron transfer beyond the Condon approximation. J Chem Phys 2016; 145:214105. [DOI: 10.1063/1.4971166] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Michael G. Mavros
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
| | - Diptarka Hait
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
| | - Troy Van Voorhis
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
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20
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Trachsel MA, Wiedmer T, Blaser S, Frey HM, Li Q, Ruiz-Barragan S, Blancafort L, Leutwyler S. The excited-state structure, vibrations, lifetimes, and nonradiative dynamics of jet-cooled 1-methylcytosine. J Chem Phys 2016; 145:134307. [DOI: 10.1063/1.4964091] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- Maria A. Trachsel
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Timo Wiedmer
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Susan Blaser
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Hans-Martin Frey
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Quansong Li
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry, Beijing Institute of Technology, 100081 Beijing, China
| | - Sergi Ruiz-Barragan
- Lehrstuhl für Theoretische Chemie, Ruhr-Universitat Bochum, 44780 Bochum, Germany
| | - Lluís Blancafort
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Facultat de Ciències, C/ M. Aurèlia Campmany 69, 17003 Girona, Spain
| | - Samuel Leutwyler
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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21
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Padula D, Jurinovich S, Di Bari L, Mennucci B. Simulation of Electronic Circular Dichroism of Nucleic Acids: From the Structure to the Spectrum. Chemistry 2016; 22:17011-17019. [PMID: 27699878 DOI: 10.1002/chem.201602777] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Indexed: 12/18/2022]
Abstract
We present a quantum mechanical (QM) simulation of the electronic circular dichroism (ECD) of nucleic acids (NAs). The simulation combines classical molecular dynamics, to obtain the structure and its temperature-dependent fluctuations, with a QM excitonic model to determine the ECD. The excitonic model takes into account environmental effects through a polarizable embedding and uses a refined approach to calculate the electronic couplings in terms of full transition densities. Three NAs with either similar conformations but different base sequences or similar base sequences but different conformations have been investigated and the results were compared with experimental observations; a good agreement was seen in all cases. A detailed analysis of the nature of the ECD bands in terms of their excitonic composition was also carried out. Finally, a comparison between the QM and the DeVoe models clearly revealed the importance of including fluctuations of the excitonic parameters and of accurately determining the electronic couplings. This study demonstrates the feasibility of the ab initio simulation of the ECD spectra of NAs, that is, without the need of experimental structural or electronic data.
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Affiliation(s)
- Daniele Padula
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, 56124, Pisa, Italy
| | - Sandro Jurinovich
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, 56124, Pisa, Italy
| | - Lorenzo Di Bari
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, 56124, Pisa, Italy
| | - Benedetta Mennucci
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, 56124, Pisa, Italy
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22
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Beckstead AA, Zhang Y, de Vries MS, Kohler B. Life in the light: nucleic acid photoproperties as a legacy of chemical evolution. Phys Chem Chem Phys 2016; 18:24228-38. [PMID: 27539809 DOI: 10.1039/c6cp04230a] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Photophysical investigations of the canonical nucleobases that make up DNA and RNA during the past 15 years have revealed that excited states formed by the absorption of UV radiation decay with subpicosecond lifetimes (i.e., <10(-12) s). Ultrashort lifetimes are a general property of absorbing sunscreen molecules, suggesting that the nucleobases are molecular survivors of a harsh UV environment. Encoding the genome using photostable building blocks is an elegant solution to the threat of photochemical damage. Ultrafast excited-state deactivation strongly supports the hypothesis that UV radiation played a major role in shaping molecular inventories on the early Earth before the emergence of life and the subsequent development of a protective ozone shield. Here, we review the general physical and chemical principles that underlie the photostability, or "UV hardiness", of modern nucleic acids and discuss the possible implications of these findings for prebiotic chemical evolution. In RNA and DNA strands, much longer-lived excited states are observed, which at first glance appear to increase the risk of photochemistry. It is proposed that the dramatically different photoproperties that emerge from assemblies of photostable building blocks may explain the transition from a world of molecular survival to a world in which energy-rich excited electronic states were eventually tamed for biological purposes such as energy transduction, signaling, and repair of the genetic machinery.
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Affiliation(s)
- Ashley A Beckstead
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717-3400, USA.
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23
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Pino GA, Feraud G, Broquier M, Grégoire G, Soorkia S, Dedonder C, Jouvet C. Non-radiative processes in protonated diazines, pyrimidine bases and an aromatic azine. Phys Chem Chem Phys 2016; 18:20126-34. [PMID: 27110833 DOI: 10.1039/c6cp01345g] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The excited state lifetimes of DNA bases are often very short due to very efficient non-radiative processes assigned to the ππ*-nπ* coupling. A set of protonated aromatic diazine molecules (pyridazine, pyrimidine and pyrazine C4H5N2(+)) and protonated pyrimidine DNA bases (cytosine, uracil and thymine), as well as the protonated pyridine (C5H6N(+)), have been investigated. For all these molecules except one tautomer of protonated uracil (enol-keto), electronic spectroscopy exhibits vibrational line broadening. Excited state geometry optimization at the CC2 level has been conducted to find out whether the excited state lifetimes measured from line broadening can be correlated to the calculated ordering of the ππ* and nπ* states and the ππ*-nπ* energy gap. The short lifetimes, observed when one nitrogen atom of the ring is not protonated, can be rationalized by relaxation of the ππ* state to the nπ* state or directly to the electronic ground state through ring puckering.
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Affiliation(s)
- Gustavo A Pino
- Instituto de Investigaciones en Físico Química de Córdoba (INFIQC) CONICET - UNC. Dpto. de Fisicoquímica - Facultad de Ciencias Químicas - Centro Láser de Ciencias Moleculares - Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Géraldine Feraud
- CNRS, Aix Marseille Université, PIIM UMR 7345, 13397, Marseille, France.
| | - Michel Broquier
- Centre Laser de l'Université Paris-Sud (CLUPS/LUMAT), Univ. Paris-Sud, CNRS, IOGS, Université Paris-Saclay, F-91405 Orsay, France and Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Gilles Grégoire
- Centre Laser de l'Université Paris-Sud (CLUPS/LUMAT), Univ. Paris-Sud, CNRS, IOGS, Université Paris-Saclay, F-91405 Orsay, France and Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Satchin Soorkia
- Centre Laser de l'Université Paris-Sud (CLUPS/LUMAT), Univ. Paris-Sud, CNRS, IOGS, Université Paris-Saclay, F-91405 Orsay, France and Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Claude Dedonder
- CNRS, Aix Marseille Université, PIIM UMR 7345, 13397, Marseille, France.
| | - Christophe Jouvet
- CNRS, Aix Marseille Université, PIIM UMR 7345, 13397, Marseille, France.
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24
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Lobsiger S, Etinski M, Blaser S, Frey HM, Marian C, Leutwyler S. Intersystem crossing rates of S1 state keto-amino cytosine at low excess energy. J Chem Phys 2016; 143:234301. [PMID: 26696056 DOI: 10.1063/1.4937375] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The amino-keto tautomer of supersonic jet-cooled cytosine undergoes intersystem crossing (ISC) from the v = 0 and low-lying vibronic levels of its S1((1)ππ(∗)) state. We investigate these ISC rates experimentally and theoretically as a function of S1 state vibrational excess energy Eexc. The S1 vibronic levels are pumped with a ∼5 ns UV laser, the S1 and triplet state ion signals are separated by prompt or delayed ionization with a second UV laser pulse. After correcting the raw ISC yields for the relative S1 and T1 ionization cross sections, we obtain energy dependent ISC quantum yields QISC (corr)=1%-5%. These are combined with previously measured vibronic state-specific decay rates, giving ISC rates kISC = 0.4-1.5 ⋅ 10(9) s(-1), the corresponding S1⇝S0 internal conversion (IC) rates are 30-100 times larger. Theoretical ISC rates are computed using SCS-CC2 methods, which predict rapid ISC from the S1; v = 0 state with kISC = 3 ⋅ 10(9) s(-1) to the T1((3)ππ(∗)) triplet state. The surprisingly high rate of this El Sayed-forbidden transition is caused by a substantial admixture of (1)nOπ(∗) character into the S1((1)ππ(∗)) wave function at its non-planar minimum geometry. The combination of experiment and theory implies that (1) below Eexc = 550 cm(-1) in the S1 state, S1⇝S0 internal conversion dominates the nonradiative decay with kIC ≥ 2 ⋅ 10(10) s(-1), (2) the calculated S1⇝T1 ((1)ππ(∗)⇝(3)ππ(∗)) ISC rate is in good agreement with experiment, (3) being El-Sayed forbidden, the S1⇝T1 ISC is moderately fast (kISC = 3 ⋅ 10(9) s(-1)), and not ultrafast, as claimed by other calculations, and (4) at Eexc ∼ 550 cm(-1) the IC rate increases by ∼50 times, probably by accessing the lowest conical intersection (the C5-twist CI) and thereby effectively switching off the ISC decay channels.
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Affiliation(s)
- Simon Lobsiger
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Mihajlo Etinski
- Fakultet za Fizičku Hemiju, Univerzitet u Beogradu, Studentski Trg 12-16, SRB-11000 Beograd, Serbia
| | - Susan Blaser
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Hans-Martin Frey
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Christel Marian
- Institut für Theoretische Chemie und Computerchemie, Heinrich-Heine Universität, Universitätsstrasse 1, D-40225 Düsseldorf, Germany
| | - Samuel Leutwyler
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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25
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Kancheva P, Tuna D, Delchev VB. Comparative study of radiationless deactivation mechanisms in cytosine and 2,4-diaminopyrimidine. J Photochem Photobiol A Chem 2016. [DOI: 10.1016/j.jphotochem.2016.02.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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Ma C, Cheng CCW, Chan CTL, Chan RCT, Kwok WM. Remarkable effects of solvent and substitution on the photo-dynamics of cytosine: a femtosecond broadband time-resolved fluorescence and transient absorption study. Phys Chem Chem Phys 2016; 17:19045-57. [PMID: 26126728 DOI: 10.1039/c5cp02624e] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cytosine (Cyt) among all the nucleic acid bases features the most complex and least understood nonradiative deactivation, a process that is crucially important for its photostability. Herein, the excited state dynamics of Cyt and a series of its N1- and C5-derivatives, including the full set of Cyt nucleosides and nucleotides in DNA and RNA and the nucleosides of 5-methyl cytosine, 5-methylcytidine and 2'-deoxy-5-methylcytidine, have been investigated in water and in methanol employing femtosecond broadband time-resolved fluorescence coupled with fs transient absorption spectroscopy. The results reveal remarkable state-specific effects of the substitution and solvent in tuning distinctively the timescales and pathways of the nonradiative decays. For Cyt and the N1-derivatives, the nonradiative deactivations occur in a common two-state process through three channels, two from the light-absorbing ππ* state with respectively the sub-picosecond (∼0.2 ps) and the picosecond (∼1.5 ps) time constant, and the third is due to an optically dark nπ* state with the lifetime ranging from several to hundreds of picoseconds depending on solvents and substitutions. Compared to Cyt, the presence of the ribose or deoxyribose moiety at the N1 position of N1-derivatives facilitates the formation of the nπ* at the sub-picosecond timescale and at the same time increases its lifetime by ∼4-6 times in both water and methanol. In sharp contrast, the existence of the methyl group at the C5 position of the C5-derivatives eliminates completely the sub-picosecond ππ* channel and the channel due to the nπ*, but on the other hand slows down the decay of the ππ* state which after relaxation exhibits a single time constant of ∼4.1 to ∼7.6 ps depending on solvents. Varying the solvent from water to methanol accelerates only slightly the decay of the ππ* state in all the compounds; while for Cyt and its N1-derivatives, this change of solvent also retards strongly the nπ* channel, prolongs its lifetime from such as ∼7.7 ps in water to ∼52 ps in methanol for Cyt and from ∼30 ps in water to ∼186 ps in methanol for deoxycytidine. The spectral signatures we obtained for the ππ* and the nπ* states allow unambiguous evidence for clarifying uncertainties in the excited states of Cyt and the derivatives. The results provide a unifying experimental characterization at an improved level of detail about the photophysics of Cyt and its analogues under biologically relevant conditions and may help in understanding the photostability as well as photo-damages of the bases and related DNAs.
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Affiliation(s)
- Chensheng Ma
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzheng, Guangdong, P. R. China
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27
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Blaser S, Trachsel MA, Lobsiger S, Wiedmer T, Frey HM, Leutwyler S. Gas-Phase Cytosine and Cytosine-N1-Derivatives Have 0.1-1 ns Lifetimes Near the S1 State Minimum. J Phys Chem Lett 2016; 7:752-757. [PMID: 26863095 DOI: 10.1021/acs.jpclett.6b00017] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ultraviolet radiative damage to DNA is inefficient because of the ultrafast S1 ⇝ S0 internal conversion of its nucleobases. Using picosecond pump-ionization delay measurements, we find that the S1((1)ππ*) state vibrationless lifetime of gas-phase keto-amino cytosine (Cyt) is τ = 730 ps or ∼ 700 times longer than that measured by femtosecond pump-probe ionization at higher vibrational excess energy, Eexc. N1-Alkylation increases the S1 lifetime up to τ = 1030 ps for N1-ethyl-Cyt but decreases it to 100 ps for N1-isopropyl-Cyt. Increasing the vibrational energy to Eexc = 300-550 cm(-1) decreases the lifetimes to 20-30 ps. The nonradiative dynamics of S1 cytosine is not solely a property of the amino-pyrimidinone chromophore but is strongly influenced by the N1-substituent. Correlated excited-state calculations predict that the gap between the S2((1)nOπ*) and S1((1)ππ*) states decreases along the series of N1-derivatives, thereby influencing the S1 state lifetime.
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Affiliation(s)
- Susan Blaser
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Maria A Trachsel
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Simon Lobsiger
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Timo Wiedmer
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Hans-Martin Frey
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Samuel Leutwyler
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
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28
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Improta R, Santoro F, Blancafort L. Quantum Mechanical Studies on the Photophysics and the Photochemistry of Nucleic Acids and Nucleobases. Chem Rev 2016; 116:3540-93. [PMID: 26928320 DOI: 10.1021/acs.chemrev.5b00444] [Citation(s) in RCA: 341] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The photophysics and photochemistry of DNA is of great importance due to the potential damage of the genetic code by UV light. Quantum mechanical studies have played a key role in interpretating the results of modern time-resolved pump-probe spectroscopy, and in elucidating the main photoactivated reactive paths. This review provides a concise, complete picture of the computational studies carried out, approximately, in the past decade. We start with an overview of the photophysics of the nucleobases in the gas phase and in solution. We discuss the proposed mechanisms for ultrafast decay to the ground state, that involve conical intersections, consider the role of triplet states, and analyze how the solvent modulates the photophysics. Then we move to larger systems, from dinucleotides to single- and double-stranded oligonucleotides. We focus on the possible role of charge transfer and delocalized or excitonic states in the photophysics of these systems and discuss the main photochemical paths. We finish with an outlook on the current challenges in the field and future directions of research.
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Affiliation(s)
- Roberto Improta
- Istituto di Biostrutture Biommagini (IBB-CNR), CNR-Consiglio Nazionale delle Ricerche , Via Mezzocannone 16, I-80134, Napoli, Italy
| | - Fabrizio Santoro
- Area della Ricerca di Pisa, Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR), CNR-Consiglio Nazionale delle Ricerche , Via G. Moruzzi 1, I-56124 Pisa, Italy
| | - Lluís Blancafort
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus de Montilivi , 17071 Girona, Spain
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Ho J, Yen H, Shi H, Cheng L, Weng C, Chou W, Chiu C, Cheng P. Microhydration Effects on the Ultrafast Photodynamics of Cytosine: Evidences for a Possible Hydration‐Site Dependence. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201507524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jr‐Wei Ho
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Hung‐Chien Yen
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Hui‐Qi Shi
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Li‐Hao Cheng
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Chih‐Nan Weng
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Wei‐Kuang Chou
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Chih‐Chung Chiu
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Po‐Yuan Cheng
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
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Ho J, Yen H, Shi H, Cheng L, Weng C, Chou W, Chiu C, Cheng P. Microhydration Effects on the Ultrafast Photodynamics of Cytosine: Evidences for a Possible Hydration‐Site Dependence. Angew Chem Int Ed Engl 2015; 54:14772-6. [DOI: 10.1002/anie.201507524] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 09/18/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Jr‐Wei Ho
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Hung‐Chien Yen
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Hui‐Qi Shi
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Li‐Hao Cheng
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Chih‐Nan Weng
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Wei‐Kuang Chou
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Chih‐Chung Chiu
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
| | - Po‐Yuan Cheng
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 30043 (R.O.C.)
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Taccone MI, Féraud G, Berdakin M, Dedonder-Lardeux C, Jouvet C, Pino GA. Communication: UV photoionization of cytosine catalyzed by Ag+. J Chem Phys 2015; 143:041103. [DOI: 10.1063/1.4927469] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Martín I. Taccone
- INFIQC (CONICET – Universidad Nacional de Córdoba), Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Geraldine Féraud
- Physique des Interactions Ioniques et Moléculaires (PIIM): UMR- 7345, CNRS, Aix Marseille Université, 13397 Marseille, France
| | - Matías Berdakin
- INFIQC (CONICET – Universidad Nacional de Córdoba), Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
| | - Claude Dedonder-Lardeux
- Physique des Interactions Ioniques et Moléculaires (PIIM): UMR- 7345, CNRS, Aix Marseille Université, 13397 Marseille, France
| | - Christophe Jouvet
- Physique des Interactions Ioniques et Moléculaires (PIIM): UMR- 7345, CNRS, Aix Marseille Université, 13397 Marseille, France
| | - Gustavo A. Pino
- INFIQC (CONICET – Universidad Nacional de Córdoba), Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina
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Nakayama A, Yamazaki S, Taketsugu T. Quantum Chemical Investigations on the Nonradiative Deactivation Pathways of Cytosine Derivatives. J Phys Chem A 2014; 118:9429-37. [DOI: 10.1021/jp506740r] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Akira Nakayama
- Catalysis
Research Center, Hokkaido University, Sapporo 001-0021, Japan
| | - Shohei Yamazaki
- Department
of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan
| | - Tetsuya Taketsugu
- Department
of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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Lobsiger S, Trachsel MA, Den T, Leutwyler S. Excited-State Structure, Vibrations, and Nonradiative Relaxation of Jet-Cooled 5-Fluorocytosine. J Phys Chem B 2014; 118:2973-84. [DOI: 10.1021/jp500410s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Simon Lobsiger
- Department of Chemistry and
Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Maria A. Trachsel
- Department of Chemistry and
Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Takuya Den
- Department of Chemistry and
Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Samuel Leutwyler
- Department of Chemistry and
Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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Lapinski L, Reva I, Rostkowska H, Fausto R, Nowak MJ. Near-IR-Induced, UV-Induced, and Spontaneous Isomerizations in 5-Methylcytosine and 5-Fluorocytosine. J Phys Chem B 2014; 118:2831-41. [DOI: 10.1021/jp411423c] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Leszek Lapinski
- Institute
of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Igor Reva
- Department
of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Hanna Rostkowska
- Institute
of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Rui Fausto
- Department
of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Maciej J. Nowak
- Institute
of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
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Trachsel MA, Lobsiger S, Schär T, Leutwyler S. Low-lying excited states and nonradiative processes of 9-methyl-2-aminopurine. J Chem Phys 2014; 140:044331. [DOI: 10.1063/1.4862913] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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36
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Frey JA, Ottiger P, Leutwyler S. Watson–Crick and Sugar-Edge Base Pairing of Cytosine in the Gas Phase: UV and Infrared Spectra of Cytosine·2-Pyridone. J Phys Chem B 2014; 118:682-91. [DOI: 10.1021/jp409660b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jann A. Frey
- Department
of Chemistry and
Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Philipp Ottiger
- Department
of Chemistry and
Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Samuel Leutwyler
- Department
of Chemistry and
Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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37
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Chatterley AS, West CW, Stavros VG, Verlet JRR. Time-resolved photoelectron imaging of the isolated deprotonated nucleotides. Chem Sci 2014. [DOI: 10.1039/c4sc01493f] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Time-resolved photoelectron spectroscopy of deprotonated nucleotides provides new insights into their relaxation dynamics.
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Affiliation(s)
- Adam S. Chatterley
- Department
- of Chemistry
- University of Durham
- Durham DH1 3LE, United Kingdom
- Department of Chemistry
| | | | - Vasilios G. Stavros
- Department of Chemistry
- University of Warwick
- Coventry CV4 7AL, United Kingdom
| | - Jan R. R. Verlet
- Department
- of Chemistry
- University of Durham
- Durham DH1 3LE, United Kingdom
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Triandafillou CG, Matsika S. Excited-state tautomerization of gas-phase cytosine. J Phys Chem A 2013; 117:12165-74. [PMID: 24094271 DOI: 10.1021/jp407758w] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In order to investigate experimentally observed phototautomerization of gas-phase cytosine, several excited-state tautomerization mechanisms were characterized at the EOM-CCSD and TDDFT levels. All pathways that took place exclusively on the S1 surface were found to have significant barriers that were much higher than the barriers involved in radiationless decay of cytosine tautomers through conical intersections back to the ground state; tautomerization in this fashion cannot compete with radiationless relaxation. However, an alternative possibility is that the conical intersections that facilitate radiationless decay could also facilitate tautomerization. Barrierless pathways indicate that it is energetically possible that bifurcation at the conical intersections can lead to a subset of the population reaching different tautomers. This could be an explanation for the observed tautomerization of keto cytosine after exposure to low-energy UV light.
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39
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Excitation of Nucleobases from a Computational Perspective I: Reaction Paths. Top Curr Chem (Cham) 2013; 355:57-97. [DOI: 10.1007/128_2013_501] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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