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Slimak S, Lietard A, Jordan KD, Verlet JRR. Effect of N Atom Substitution on Electronic Resonances: A 2D Photoelectron Spectroscopic and Computational Study of Anthracene, Acridine, and Phenazine Anions. J Phys Chem A 2024; 128:5321-5330. [PMID: 38935624 PMCID: PMC11247488 DOI: 10.1021/acs.jpca.4c02756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 06/15/2024] [Accepted: 06/17/2024] [Indexed: 06/29/2024]
Abstract
The accommodation of an excess electron by polycyclic aromatic hydrocarbons (PAHs) has important chemical and technological implications ranging from molecular electronics to charge balance in interstellar molecular clouds. Here, we use two-dimensional photoelectron spectroscopy and equation-of-motion coupled-cluster calculations of the radical anions of acridine (C13H9N-) and phenazine (C12H8N2-) and compare our results for these species to those for the anthracene anion (C14H10-). The calculations predict the observed resonances and additionally find low-energy two-particle-one-hole states, which are not immediately apparent in the spectra, and offer a slightly revised interpretation of the resonances in anthracene. The study of acridine and phenazine allows us to understand how N atom substitution affects electron accommodation. While the electron affinity associated with the ground state anion undergoes a sizable increase with the successive substitution of N atoms, the two lowest energy excited anion states are not affected significantly by the substitution. The net result is that there is an increase in the energy gap between the two lowest energy resonances and the bound ground electronic state of the radical anion from anthracene to acridine to phenazine. Based on an energy gap law for the rate of internal conversion, this increased gap makes ground state formation progressively less likely, as evidenced by the photoelectron spectra.
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Affiliation(s)
- Stephen Slimak
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Aude Lietard
- Department
of Chemistry, Durham University, Durham DH1 3LE, U.K.
| | - Kenneth D. Jordan
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jan R. R. Verlet
- Department
of Chemistry, Durham University, Durham DH1 3LE, U.K.
- J.
Heyrovský Institute of Physical Chemistry, Czech Academy of
Sciences, Dolejškova
3, Prague 8 18223, Czech Republic
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Khatymov RV, Muftakhov MV, Tuktarov RF, Shchukin PV, Khatymova LZ, Pancras E, Terentyev AG, Petrov NI. Resonant electron capture by polycyclic aromatic hydrocarbon molecules: Effects of aza-substitution. J Chem Phys 2024; 160:124310. [PMID: 38533882 DOI: 10.1063/5.0195316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Accepted: 03/07/2024] [Indexed: 03/28/2024] Open
Abstract
Resonant electron capture by aza and diaza derivatives of phenanthrene (7,8-benzoquinoline and 1,10-phenanthroline) and anthracene (acridine and phenazine) at incident free electron energies (Ee) in the range of 0-15 eV was studied. All compounds except 7,8-benzoquinoline form long-lived molecular ions (M-) at thermal electron energies (Ee ∼ 0 eV). Acridine and phenazine also form such ions at epithermal electron energies up to Ee = 1.5-2.5 eV. The lifetimes (τa) of M- with respect to electron autodetachment are proportional to the extent of aza-substitution and increase on going from molecules with bent geometry of the fused rings (azaphenanthrenes) to linear isomers (azaanthracenes). These regularities are due to an increase in the adiabatic electron affinities (EAa) of the molecules. The EAa values of the molecules under study were comprehensively assessed based on a comparative analysis of the measured τa values using the Rice-Ramsperger-Kassel-Marcus theory, the electronic structure analysis using the molecular orbital approach, as well as the density functional calculations of the total energy differences between the molecules and anions. The only fragmentation channel of M- ions from the compounds studied is abstraction of hydrogen atoms. When studying [M-H]- ions, electron autodetachment processes were observed, the τa values were measured, and the appearance energies were determined. A comparative analysis of the gas-phase acidity of the molecules and the EAa values of the [M-H]· radicals revealed their proportionality to the EAa values of the parent molecules.
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Affiliation(s)
- Rustem V Khatymov
- Mendeleev University of Chemical Technology of Russia, Miusskaya Square, 9, 125047 Moscow, Russia
| | - Mars V Muftakhov
- Institute of Molecule and Crystal Physics, Ufa Federal Research Center, Russian Academy of Sciences, Prospekt Oktyabrya, 151, 450075 Ufa, Russia
| | - Renat F Tuktarov
- Institute of Molecule and Crystal Physics, Ufa Federal Research Center, Russian Academy of Sciences, Prospekt Oktyabrya, 151, 450075 Ufa, Russia
| | - Pavel V Shchukin
- Institute of Molecule and Crystal Physics, Ufa Federal Research Center, Russian Academy of Sciences, Prospekt Oktyabrya, 151, 450075 Ufa, Russia
| | - Lyaysan Z Khatymova
- Institute of Molecule and Crystal Physics, Ufa Federal Research Center, Russian Academy of Sciences, Prospekt Oktyabrya, 151, 450075 Ufa, Russia
| | - Eugene Pancras
- Ufa State Petroleum Technological University, ul. Kosmonavtov, 1, 450064 Ufa, Russia
| | - Andrey G Terentyev
- Mendeleev University of Chemical Technology of Russia, Miusskaya Square, 9, 125047 Moscow, Russia
| | - Nikolay I Petrov
- Mendeleev University of Chemical Technology of Russia, Miusskaya Square, 9, 125047 Moscow, Russia
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Lietard A, Mensa-Bonsu G, Verlet JRR. The effect of solvation on electron capture revealed using anion two-dimensional photoelectron spectroscopy. Nat Chem 2021; 13:737-742. [PMID: 33941903 DOI: 10.1038/s41557-021-00687-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/24/2021] [Indexed: 02/02/2023]
Abstract
The reaction of low-energy electrons with neutral molecules to form anions plays an important role in chemistry, being involved in, for example, various biological and astrochemical processes. However, key aspects of electron-molecule interactions, such as the effect of incremental solvation on the initially excited electronic resonances, remain poorly understood. Here two-dimensional photoelectron spectroscopy of anionic anthracene and nitrogen-substituted derivatives-solvated by up to five water molecules-reveals that for an incoming electron, resonances red-shift with increasing hydration; but for the anion, the excitation energies of the resonances remain essentially the same. These complementary points of view show that the observed onset of enhanced anion formation for a specific cluster size is mediated by a bound excited state of the anion. Our findings suggest that polycyclic aromatic hydrocarbons may be more efficient at electron capture than previously predicted with important consequences for the ionization fraction in dense molecular clouds.
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Affiliation(s)
- Aude Lietard
- Department of Chemistry, Durham University, Durham, UK
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Lin Z, Van Voorhis T. Triplet Tuning: A Novel Family of Non-Empirical Exchange–Correlation Functionals. J Chem Theory Comput 2019; 15:1226-1241. [DOI: 10.1021/acs.jctc.8b00853] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Zhou Lin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Troy Van Voorhis
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Harthcock C, Zhang J, Kong W, Mitsui M, Ohshima Y. Electronic spectra and excited-state dynamics of acridine and its hydrated clusters. J Chem Phys 2017; 146:134311. [PMID: 28390373 DOI: 10.1063/1.4979631] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We combine results from several different experiments to investigate the photophysics of acridine (Ac) and its hydrated clusters in the gas phase. Our findings are also compared with results from condensed phase studies. Similar to measurements of Ac dissolved in hydrocarbons, the lifetime of the first electronically excited state of isolated Ac in vacuum is too short for typical resonantly enhanced multiphoton ionization (REMPI) and laser induced fluorescence (LIF) experiments, hence no signal from REMPI and LIF can be attributed to monomeric Ac. Instead, sensitized phosphorescence emission spectroscopy is more successful in revealing the electronic states of Ac. Upon clustering with water, on the other hand, the lifetimes of the excited states are substantially increased to the nanosecond scale, and with two water molecules attached to Ac, the lifetime of the hydrated cluster is essentially the same as that of Ac in aqueous solutions. Detailed REMPI and ultraviolet-ultraviolet hole-burning experiments are then performed to reveal the structural information of the hydrated clusters. Although the formation of hydrogen bonds results in energy level reversal and energy separation between the first two excited states of Ac, its effect on the internal geometry of Ac is minimal, and all clusters with 1-3 water molecules demonstrate consistent intramolecular vibrational modes. Theoretical calculations reveal just one stable structure for each cluster under supersonic molecular beam conditions. Furthermore, different from mono- and di-water clusters, tri-water clusters consist of a linear chain of three water molecules attached to Ac. Consequently, the fragmentation pattern in the REMPI spectrum of tri-water clusters seems to be dominated by water trimer elimination, since the REMPI spectrum of Ac+·W3 is largely reproduced in the Ac+ mass channel, but not in the Ac+·W1 or Ac+·W2 channel.
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Affiliation(s)
- Colin Harthcock
- Department of Chemistry, Oregon State University Corvallis, Oregon 97331, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University Corvallis, Oregon 97331, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University Corvallis, Oregon 97331, USA
| | - Masaaki Mitsui
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Yasuhiro Ohshima
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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Nakajima A. Study on Electronic Properties of Composite Clusters toward Nanoscale Functional Advanced Materials. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2013. [DOI: 10.1246/bcsj.20120298] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Atsushi Nakajima
- Department of Chemistry, Faculty of Science and Technology, Keio University
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Mitsui M, Nakajima A. Formation of Large Molecular Cluster Anions and Elucidation of Their Electronic Structures. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2007. [DOI: 10.1246/bcsj.80.1058] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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