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Suzuki R, Chiba K, Tanaka S, Okuyama K. Electronic spectra of jet-cooled 1,4-bis(phenylethynyl)benzene: Strength in π-electron conjugation and two large-amplitude torsional motions. J Chem Phys 2024; 160:024301. [PMID: 38189806 DOI: 10.1063/5.0176162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 10/30/2023] [Indexed: 01/09/2024] Open
Abstract
To spectroscopically qualify strength in the π-electron conjugation, the electronic spectra of jet-cooled 1,4-bis(phenylethynyl)benzene (BPEB) in the region of the transition to the lowest excited singlet (S1) 1B1u state are measured by the fluorescence excitation and the single-vibronic-level dispersed fluorescence methods. Strength is defined as the difference in potential energies between the planar and perpendicular conformations. BPEB possesses two large-amplitude torsional motions, out-of-phase 24 and in-phase 29 modes. The most stable is the planar conformation, and barrier heights at the perpendicular conformation are coincident in torsional potentials for the two modes. Torsional levels are successively observed up to 19± and 16- quantum levels in the ground state, respectively. Strength is determined to be 293 cm-1 (3.51 kJmol-1) with an accuracy of an error range smaller than 1 cm-1. In the excited state, strength is estimated to be 1549 ± 73 cm-1. Combination levels of two torsional modes are also measured up to high quantum levels. A systematic decrease in frequencies is observed with increasing the quantum number. Quantum-chemistry calculations of B3LYP, CAM-B3PLYP, WB97XD, and M062X with basis sets of aug-cc-pVDZ are performed, where B3LYP theories are carried out with the dispersion correlation. The calculated strength is 1.1-2.1 times larger than observed.
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Affiliation(s)
- Ryoko Suzuki
- Departments of Chemical Biology and Applied Chemistry, Graduate School of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
| | - Kohei Chiba
- Departments of Chemical Biology and Applied Chemistry, Graduate School of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
| | - Sei'ichi Tanaka
- Departments of Chemical Biology and Applied Chemistry, Graduate School of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
| | - Katsuhiko Okuyama
- Departments of Chemical Biology and Applied Chemistry, College of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
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Peterson BN, Alfieri ME, Hood DJ, Hettwer CD, Costantino DV, Tabor DP, Kidwell NM. Solvent-Mediated Charge Transfer Dynamics of a Model Brown Carbon Aerosol Chromophore: Photophysics of 1-Phenylpyrrole Induced by Water Solvation. J Phys Chem A 2022; 126:4313-4325. [PMID: 35776530 DOI: 10.1021/acs.jpca.2c00585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitrogen heterocycles are known to be important light-absorbing chromophores in a newly discovered class of aerosols, commonly referred to as "brown carbon" (BrC) aerosols. Due to their significant absorption and spectral overlap with the solar actinic flux, these BrC chromophores steer the physical and optical properties of aerosols. To model the local aqueous solvation environment surrounding BrC chromophores, we generated cold molecular complexes with water and a prototypical BrC chromophore, 1-phenylpyrrole (1PhPy), using supersonic jet-cooling and explored their intermolecular interactions using single-conformation spectroscopy. Herein, we utilized resonant two-photon ionization (R2PI) and UV holeburning (UV HB) double-resonance spectroscopies to obtain a molecular-level understanding of the role of water microsolvation in charge transfer upon photoexcitation of 1PhPy. Quantum chemical calculations and one-dimensional discrete variable representation simulations revealed insights into the charge transfer efficacy of 1PhPy with and without addition of a single water molecule. Taken together, our results indicate that the intermolecular interactions with water guide the geometry of 1PhPy to adopt a more twisted intramolecular charge transfer (TICT) configuration, thus facilitating charge transfer from the pyrrole donor to the phenyl ring acceptor. Furthermore, the water network surrounding 1PhPy reports on the charge transfer such that the H2O solvent primarily interacts with the pyrrole ring donor in the ground state, whereas it preferentially interacts with the phenyl ring acceptor in the excited state. Large Franck-Condon activity is evident in the 1PhPy + 1H2O excitation spectrum for the water-migration vibronic bands, supporting H2O solvent reorganization upon excitation of the 1PhPy chromophore. Fluorescence measurements with increasing H2O % volume corroborated our gas-phase studies by indicating that a polar water solvation environment stabilizes the TICT configuration of 1PhPy in the excited electronic state, from which emission is observed at a lower energy compared to the locally excited configuration.
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Affiliation(s)
- Brianna N Peterson
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, United States
| | - Megan E Alfieri
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, United States
| | - David J Hood
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, United States
| | - Christian D Hettwer
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, United States
| | - Daniel V Costantino
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, United States
| | - Daniel P Tabor
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Nathanael M Kidwell
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, United States
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3
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Schouder CA, Chatterley AS, Pickering JD, Stapelfeldt H. Laser-Induced Coulomb Explosion Imaging of Aligned Molecules and Molecular Dimers. Annu Rev Phys Chem 2022; 73:323-347. [PMID: 35081323 DOI: 10.1146/annurev-physchem-090419-053627] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We discuss how Coulomb explosion imaging (CEI), triggered by intense femtosecond laser pulses and combined with laser-induced alignment and covariance analysis of the angular distributions of the recoiling fragment ions, provides new opportunities for imaging the structures of molecules and molecular complexes. First, focusing on gas phase molecules, we show how the periodic torsional motion of halogenated biphenyl molecules can be measured in real time by timed CEI, and how CEI of one-dimensionally aligned difluoroiodobenzene molecules can uniquely identify four structural isomers. Next, focusing on molecular complexes formed inside He nanodroplets, we show that the conformations of noncovalently bound dimers or trimers, aligned in one or three dimensions, can be determined by CEI. Results presented for homodimers of CS2, OCS, and bromobenzene pave the way for femtosecond time-resolved structure imaging of molecules undergoing bimolecular interactions and ultimately chemical reactions. Expected final online publication date for the Annual Review of Physical Chemistry, Volume 73 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Fleisher AJ, Bird RG, Zaleski DP, Pate BH, Pratt DW. High-Resolution Electronic Spectroscopy of the Doorway States to Intramolecular Charge Transfer. J Phys Chem B 2012; 117:4231-40. [DOI: 10.1021/jp3041296] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Adam J. Fleisher
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania
15260, United States
| | - Ryan G. Bird
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania
15260, United States
| | - Daniel P. Zaleski
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904,
United States
| | - Brooks H. Pate
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904,
United States
| | - David W. Pratt
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania
15260, United States
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Chen F, Zhang J, Wan X. Design and Synthesis of Piezochromic Materials Based on Push-Pull Chromophores: A Mechanistic Perspective. Chemistry 2012; 18:4558-67. [DOI: 10.1002/chem.201102929] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2011] [Indexed: 11/10/2022]
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Fdez. Galván I, Martín ME, Muñoz-Losa A, Sánchez ML, Aguilar MA. Solvent Effects on the Structure and Spectroscopy of the Emitting States of 1-Phenylpyrrole. J Chem Theory Comput 2011; 7:1850-7. [DOI: 10.1021/ct2001182] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Ignacio Fdez. Galván
- Química Física, Edif. José María Viguera Lobo, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz, Spain
| | - M. Elena Martín
- Química Física, Edif. José María Viguera Lobo, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz, Spain
| | - Aurora Muñoz-Losa
- Química Física, Edif. José María Viguera Lobo, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz, Spain
| | - M. Luz Sánchez
- Química Física, Edif. José María Viguera Lobo, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz, Spain
| | - Manuel A. Aguilar
- Química Física, Edif. José María Viguera Lobo, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz, Spain
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Tanaka SI, Okuyama K. Internal rotation of methyl group in electronically excitedo-andm-ethynyltoluene: New correlation between the Hammett substituent constant σmand rotational barrier change. J Chem Phys 2011; 134:084311. [DOI: 10.1063/1.3535596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Tanaka S, Okuyama K. Electronic spectra of jet-cooled isoindoline: spectroscopic determination of energy difference between conformational isomers. J Chem Phys 2010; 132:164309. [PMID: 20441277 DOI: 10.1063/1.3360307] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The electronic spectra of jet-cooled isoindoline between the electronic ground (S(0)) state and the pi pi(*) lowest-excited singlet state (S(1)) were observed by the fluorescence excitation and single-vibronic-level dispersed fluorescence methods. The low-frequency progression due to the puckering vibration appeared in both spectra. Analysis of dispersed spectra together with geometry optimization at the level of B3LYP/6-311+G(d) indicated the presence of conformational isomers possessing axial and equatorial N-H bonds with respect to the molecular plane. The 0-0 bands of the axial and equatorial conformers were measured at 37,022 and 36,761 cm(-1), respectively. Three common levels in the S(1) state accessible from the respective S(0)-state zero levels were observed. From their transition frequencies, the S(0)-state energy difference between the isomers was determined to be 47.7+/-0.2 cm(-1), where the axial conformer was more stable. In the S(1) state, the energy difference was 213.7+/-0.2 cm(-1), and the equatorial conformer was more stable. The cause of switching from a stable conformation upon excitation is discussed in terms of the electron conjugation between the pi(*) orbital in benzene and the lone pair orbital of nitrogen.
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Affiliation(s)
- Sei'ichi Tanaka
- Department of Materials Chemistry and Engineering, College of Engineering, Nihon University, Koriyama 963-8642, Japan
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Newby JJ, Müller CW, Liu CP, Zwier TS. Jet-cooled vibronic spectroscopy and asymmetric torsional potentials of phenylcyclopentene. Phys Chem Chem Phys 2009; 11:8330-41. [PMID: 19756289 DOI: 10.1039/b903830b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The ultraviolet spectroscopy of the S(1) <-- S(0) transition of 1-phenylcyclopentene (PCP) was studied by resonant-two-photon ionization (R2PI), laser-induced fluorescence (LIF) and single vibronic level fluorescence (SVLF). UV-UV hole-burning (UVHB) spectroscopy was used to determine that there is only one spectroscopically distinct conformer in the supersonic expansion. The excitation spectrum shows extensive vibronic structure extending to over 1000 cm(-1) above the electronic origin (34,646 cm(-1)). Much of the vibronic structure is similar to that of styrene and other singly substituted benzene derivatives, with Franck-Condon (FC) activity predominantly in substituent-sensitive benzene modes. Sizeable FC progressions were also found in the inter-ring torsion, reflecting a large displacement in the inter-ring angle upon electronic excitation. No evidence for FC activity in the ring-puckering coordinate is observed. The torsional potentials of the ground and excited states were determined from the experimental transition frequencies by fitting the calculated to the experimental torsional frequency spacings in an automated least-squares fitting procedure. The S(1) torsional potential is a symmetric single-well potential centered around a locally planar equilibrium geometry at a torsional angle of varphi = 0 degrees . The energy levels are reproduced by a cosine term potential function with torsional parameters V(2) = 3765 cm(-1) and V(4) = -183 cm(-1). The S(0) torsional potential possesses a twisted equilibrium geometry that is strongly asymmetric about varphi = 0 degrees due to the non-planarity of the cyclopentene ring. The best-fit potential parameters uses a sin/cos potential function (odd/even), with V = 948 cm(-1), V = -195 cm(-1), V = -162 cm(-1) and V = -268 cm(-1). The shape of the potentials are similar to those predicted by relaxed potential energy scans calculated at the DFT, CIS and TDDFT//CIS levels of theory. The change in the torsional angle varphi upon electronic excitation was determined to be approximately 15 degrees from fits of the displacement delta of the S(0) torsional potential with respect to the S(1) potential. The simulated shift of the S(0) potential with respect to the S(1) potential of approximately 15 degrees is in very good agreement with that obtained from B3LYP calculations.
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Affiliation(s)
- Josh J Newby
- Department of Chemistry, Purdue University, West Lafayette, IN 47907-2084, USA
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Itoh T, Numata Y. Spectroscopy and Photophysics of Low-Lying Excited Singlet States of α,ω-Dithienylbutadiene and α,ω-Dithienylethylene Vapors. J Phys Chem A 2009; 113:10160-6. [DOI: 10.1021/jp901180a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Takao Itoh
- Graduate School of Integrated Arts and Science, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima City, 739-8521 Japan, and Department of Materials Chemistry and Engineering, College of Engineering, Nihon University, Koriyama, 963-8642 Japan
| | - Yasushi Numata
- Graduate School of Integrated Arts and Science, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima City, 739-8521 Japan, and Department of Materials Chemistry and Engineering, College of Engineering, Nihon University, Koriyama, 963-8642 Japan
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11
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Numata Y, Toyoshima S, Okuyama K, Yasunami M, Suzuka I. S1-State Internal Conversion of Isolated Azulene Derivatives. J Phys Chem A 2009; 113:9603-11. [DOI: 10.1021/jp8078502] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yasushi Numata
- Department of Materials Chemistry and Engineering, College of Engineering, Nihon University, Koriyama 963-8642, Japan
| | - Satoru Toyoshima
- Department of Materials Chemistry and Engineering, College of Engineering, Nihon University, Koriyama 963-8642, Japan
| | - Katsuhiko Okuyama
- Department of Materials Chemistry and Engineering, College of Engineering, Nihon University, Koriyama 963-8642, Japan
| | - Masafumi Yasunami
- Department of Materials Chemistry and Engineering, College of Engineering, Nihon University, Koriyama 963-8642, Japan
| | - Isamu Suzuka
- Department of Materials Chemistry and Engineering, College of Engineering, Nihon University, Koriyama 963-8642, Japan
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12
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Control of charge transfer by conformational and electronic effects: Donor–donor and donor–acceptor phenyl pyrroles. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2009.02.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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13
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Newby JJ, Liu CP, Müller CW, Zwier TS. Jet-cooled vibronic spectroscopy of potential intermediates along the pathway to PAH: phenylcyclopenta-1,3-diene. Phys Chem Chem Phys 2009; 11:8316-29. [DOI: 10.1039/b903827b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Alvarez-Valtierra L, Pratt DW. Rotationally resolved electronic spectra of 9,10-dihydrophenanthrene. A “floppy” molecule in the gas phase. J Chem Phys 2007; 126:224308. [PMID: 17581055 DOI: 10.1063/1.2732753] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Rotationally resolved fluorescence excitation spectra of several bands in the S1<--S0 electronic spectrum of 9,10-dihydrophenanthrene (DHPH) have been observed and assigned. Each band was fit using rigid rotor Hamiltonians in both electronic states. Analyses of these data reveal that DHPH has a nonplanar configuration in its S0 state with a dihedral angle between the aromatic rings (phi) of approximately 21.5 degrees. The data also show that excitation of DHPH with UV light results in a more planar structure of the molecule in the electronically excited state, with phi approximately 8.5 degrees. Three prominent Franck-Condon progressions appear in the low resolution spectrum, all with fundamental frequencies lying below 300 cm(-1). Estimates of the potential energy surfaces along each of these coordinates have been obtained from analyses of the high resolution spectra. The remaining barrier to planarity in the S1 state is estimated to be approximately 2650 cm(-1) along the bridge deformation mode and is substantially reduced by excitation of the molecule along the (orthogonal) ring twisting coordinate.
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15
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The crystal structure and vibrational spectra of two molecules emitting dual fluorescence: 4-(1H-Pyrrol-1-yl)benzonitrile (PBN) and 5-cyano-2-(1pyrrolyl)-pyridine (CPP). Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.01.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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The vibrational spectra of N-phenylpyrrole in the gas phase, in argon matrices and in single crystals. Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.01.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Cogan S, Zilberg S, Haas Y. The Electronic Origin of the Dual Fluorescence in Donor−Acceptor Substituted Benzene Derivatives. J Am Chem Soc 2006; 128:3335-45. [PMID: 16522115 DOI: 10.1021/ja0548945] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The origin of the dual fluorescence of DMABN (dimethylaminobenzonitrile) and other benzene derivatives is explained by a charge transfer model based on the properties of the benzene anion radical. It is shown that, in general, three low-lying electronically excited states are expected for these molecules, two of which are of charge transfer (CT) character, whereas the third is a locally excited (LE) state. Dual fluorescence may arise from any two of these states, as each has a different geometry at which it attains a minimum. The Jahn-Teller induced distortion of the benzene anion radical ground state helps to classify the CT states as having quinoid (Q) and antiquinoid (AQ) forms. The intramolecular charge transfer (ICT) state is formed by the transfer of an electron from a covalently linked donor group to an anti-bonding orbital of the pi-electron system of benzene. The change in charge distribution of the molecule in the CT states leads to the most significant geometry change undergone by the molecule which is the distortion of the benzene ring to a Q or AQ structure. As the dipole moment is larger in the perpendicular geometry than in the planar one, this geometry is preferred in polar solvents, supporting the twisted intramolecular charge transfer (TICT) model. However, in many cases the planar conformation of CT excited states is lower in energy than that of the LE state, and dual fluorescence can be observed also from planar structures.
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Affiliation(s)
- Semyon Cogan
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem, Israel
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Xu X, Cao Z, Zhang Q. Computational Characterization of Low-Lying States and Intramolecular Charge Transfers in N-Phenylpyrrole and the Planar-Rigidized Fluorazene. J Phys Chem A 2006; 110:1740-8. [PMID: 16451003 DOI: 10.1021/jp055695a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Low-lying states and intramolecular charge transfers in N-phenylpyrrole (PP) and its planar-rigidized derivative fluorazene (FPP) have been investigated by ab initio methodologies. On the basis of calculations, properties of the excited states and plausible dual-fluorescence mechanisms have been elucidated. Present results show that S2 as a key state is involved in the consecutive photophysical processes. The S2 state is easily populated under excitation. In the polar MeCN solution, S2 can evolve to either a lower-energy locally excited state or a lower-energy solvated intramolecular charge-transfer state (S-ICT). The former emits a normal fluorescence back to the ground state, and the latter is exclusively responsible for the red-shifted fluorescence band. Calculations reveal that the emissive ICT states in both FPP and PP have similar geometric features, an elongated N-phenyl bond, a pyramidal carbon atom linking the pyrrole ring, and a quinonoid phenyl ring. The twisting of molecule around the N-phenyl bond is not necessary for the intramolecular charge transfer. Predicted absorption and emission spectra are in reasonable agreement with the experimental observations.
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Affiliation(s)
- Xuefei Xu
- Department of Chemistry, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
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Photophysical properties of pyrrolobenzenes with different linking and substitution pattern: The transition between charge transfer states with large (MICT) and small (TICT) resonance interaction. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.06.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Schweke D, Haas Y, Dick B. Photophysics of Phenylpyrrole Derivatives and Their Acetonitrile Clusters in the Gas Phase and in Argon Matrixes: Simulations of Structure and Reactivity. J Phys Chem A 2005; 109:3830-42. [PMID: 16833699 DOI: 10.1021/jp0500844] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Recent experiments on the dual fluorescence of phenylpyrrole (PP) and pyrrolobenzonitrile (PBN) in supersonic jets and in cryogenic matrixes are analyzed. The structures of the 1:1 clusters are calculated using ab initio, density functional theory (DFT) and molecular mechanics (MM) methods. In these calculations, the structures of PP and PBN in the ground state and in two possible minima on the charge-transfer excited state are taken from a recent theoretical analysis. The structures of PP and PBN clusters with a larger number of acetonitrile molecules are also calculated using the molecular mechanics method. It is shown that the fact that small PP:AN and PBN:AN clusters do not exhibit any charge-transfer (CT) type emission, whereas for PBN:AN(n) clusters (n > or = 4) CT emission is observed, can be understood on the basis of the calculated structures. The trapping of PP and of PBN in an argon matrix (neat and doped with acetonitrile) is simulated by a molecular dynamics procedure. The observation of locally excited (LE) fluorescence only from PP in neat argon, whereas from argon-trapped PBN both CT and LE emission bands are observed, is readily understood on the basis of these simulations. Moreover, the appearance of CT emission from PP-doped argon matrixes when acetonitrile is added is also explained, as well as the relatively small spectral shift observed upon addition of acetonitrile to PBN-doped argon matrixes.
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Affiliation(s)
- D Schweke
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem, Israel 91904
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Yoshihara T, Druzhinin SI, Demeter A, Kocher N, Stalke D, Zachariasse KA. Kinetics of Intramolecular Charge Transfer with N-Phenylpyrrole in Alkyl Cyanides. J Phys Chem A 2005; 109:1497-509. [PMID: 16833471 DOI: 10.1021/jp046586j] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
For the electron acceptor/donor molecule N-phenylpyrrole (PP), the fast intramolecular charge transfer (ICT) reaction accompanied by dual fluorescence from a locally excited (LE) and an ICT state is investigated in alkyl cyanide solvents as a function of temperature. After a comparison of the X-ray crystal structure of PP with calculations from the literature, absorption and fluorescence spectra of PP in a series of solvents over a wide polarity range are discussed. ICT with PP strongly depends on solvent polarity and starts to appear in solvents more polar than diethyl ether. From an analysis of the ICT/LE fluorescence quantum yield ratio Phi'(ICT)/Phi(LE), approximate data for the change in enthalpy -DeltaH of the ICT reaction of PP are obtained, ranging from 9 kJ/mol in acetonitrile (MeCN) to 4 kJ/mol in n-butyl cyanide (BuCN). From ICT and LE fluorescence decays of PP measured as a function of temperature, the forward (Ea = 9 kJ/mol in ethyl cyanide (EtCN) and 6 kJ/mol in MeCN) and backward (Ed = 16 kJ/mol in EtCN and MeCN) ICT reaction barriers are determined. From these data, -Delta H (7 kJ/mol (EtCN); 10 kJ/mol (MeCN)) is calculated, in good agreement with the results coming from Phi'(ICT)/Phi(LE). The data for Ea show that the forward ICT barrier becomes smaller with increasing solvent polarity, whereas the absence of change for Ed comes from the compensating increase of -DeltaH. Both observations are indicative of a late transition state for the LE --> ICT reaction. For PP in EtCN and MeCN, the ICT radiative rate constant k'(f)(ICT) increases with temperature. This is caused by the ICT low transition dipole moment and hence does not contain information on the molecular structure (twisted or planar) of the ICT state. The fast ICT observed with PP supports our previous conclusion, based on a comparison of PP with its planarized derivative fluorazene, that the pyrrole and phenyl moieties in the ICT state of PP are coplanar and possess substantial electronic coupling.
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Affiliation(s)
- Toshitada Yoshihara
- Max-Planck-Institut für biophysikalische Chemie, Spektroskopie und Photochemische Kinetik, 37070 Göttingen, Germany
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Robertson EG, Thompson CD, Morrison RJS. Interplanar torsion in the S[sub 1]←S[sub 0] electronic spectrum of jet cooled 1-phenylimidazole. J Chem Phys 2004; 121:12421-7. [PMID: 15606262 DOI: 10.1063/1.1822922] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The S(1)<--S(0) transition of 1-phenylimidazole (1PI) has been studied in a supersonic jet expansion by resonant two-photon ionization. The origin band at 36 075 cm(-1) is accompanied by a low frequency progression associated with torsion about the bond connecting phenyl and imidazole groups. Torsional potentials have been determined for both states. In S(0), phi(min)=37.2+/-0.5 degrees and the planar barrier is 339+/-20 cm(-1), while in S(1), phi(min)=17.6+/-0.5 degrees and the planar barrier is 57+/-2 cm(-1). The transition moment alignment is observed to be consistent with an excited state of L(b) character, in spite of the "off-axis" conjugation provided by the imidazole ring. These results are compared with ab initio calculations on both states, performed using Hartree-Fock, Møller-Plesset second-order perturbation, density functional theory with the Becke3-Lee-Yang-Parr functional, time-dependent density functional theory, configuration interaction singles, and complete active space self-consistent field methods. Solution-phase UV spectra of neutral and protonated 1PI are also reported.
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Affiliation(s)
- Evan G Robertson
- School of Chemistry, P.O. Box 23, Monash University, Victoria 3800, Australia
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23
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Fuss W, Rettig W, Schmid WE, Trushin SA, Yatsuhashi T. Ultrafast temporary charge transfer in pyrrolidinyl–benzonitrile and pyrrolyl–benzonitrile in the gas phase. Faraday Discuss 2004; 127:23-33. [PMID: 15471337 DOI: 10.1039/b313691d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
4-(N-pyrrolidinyl)benzonitrile and 4-(N-pyrrolyl)benzonitrile were excited by an ultrashort pulse at 270 nm to their La (S2) states and then probed by ionization at long wavelengths. Parent and fragment ion signals show components with time constants < 100 fs which we attribute to ultrafast relaxation to the Lb (S1) state. From this short time we infer a conical intersection between the Lb and La surfaces. The wave packet can branch there, one part going temporarily to a strongly displaced state. Its shift was concluded from an anisotropy observed only there. The only excited state known to have a large displacement is the charge-transfer (CT) state. The positive anisotropy indicates that the CT state belongs to the 2A species for both molecules. For pyrrolylbenzonitrile, this is in contrast to previous assignments. The anisotropy, and a coherent oscillation observed in pyrrolidinylbenzonitrile, support the idea that the amino-group twist is an important component of the CT reaction coordinate.
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Affiliation(s)
- Werner Fuss
- Max-Planck-Institut für Quantenoptik, D-85741 Garching, Germany
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24
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Schweke D, Haas Y. The Fluorescence of N-Phenylpyrrole in an Argon/Acetonitrile Matrix. J Phys Chem A 2003. [DOI: 10.1021/jp035959y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Danielle Schweke
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yehuda Haas
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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25
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Grabowski ZR, Rotkiewicz K, Rettig W. Structural Changes Accompanying Intramolecular Electron Transfer: Focus on Twisted Intramolecular Charge-Transfer States and Structures. Chem Rev 2003; 103:3899-4032. [PMID: 14531716 DOI: 10.1021/cr940745l] [Citation(s) in RCA: 2251] [Impact Index Per Article: 107.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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26
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Ionescu S, Chiorescu I, Hillebrand M. Theoretical study of non-radiative deactivation pathways for some heterocyclic compounds. I. Pyrrolyl-izoxazole derivatives. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0166-1280(03)00150-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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27
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Yoshihara T, Galievsky VA, Druzhinin SI, Saha S, Zachariasse KA. Singlet excited state dipole moments of dual fluorescent N-phenylpyrroles and 4-(dimethylamino)benzonitrile from solvatochromic and thermochromic spectral shifts. Photochem Photobiol Sci 2003; 2:342-53. [PMID: 12713236 DOI: 10.1039/b211838f] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The excited state dipole moments mue(ICT) and mue(LE) of the dual fluorescent molecules N-phenylpyrrole (PP), N-(4-cyanophenyl)pyrrole (PP4C) and N-(3-cyanophenyl)pyrrole (PP3C) are determined from solvatochromic and thermochromic measurements. It is shown that the best results are obtained when the solvatochromic as well as the thermochromic analysis of the spectral shifts is made relative to 4-(dimethylamino)benzonitrile (DMABN) as the model compound. Direct thermochromic experiments with PP4C, PP3C and DMABN in diethyl ether lead to reasonable results, but unrealistically large dipole moments mue(ICT) are found for PP, PP4C, PP3C and DMABN in acetonitrile, ethyl cyanide and n-propyl cyanide. The mue(ICT) values obtained for the N-phenylpyrroles from the thermochromic analysis in these solvents relative to DMABN (17 D) do not depend on solvent polarity: 13 D for PP, 15 D for PP4C and PP3C. The spectral shifts for the LE emission of the N-phenylpyrroles and aminobenzonitriles are much smaller than those for the ICT fluorescence, resulting in relatively small values for mue(LE). With PP and N-(4-methylphenyl)pyrrole (PP4M) the problem arises that one of the two values calculated by solving the quadratic equation for mue(LE) in the solvatochromic and thermochromic analysis cannot be discarded on photophysical or molecular grounds, as is the case for the other molecules. The experimental data for mue(ICT) of PP and PP4C are compared with theoretical values calculated for coplanar (PICT) and perpendicular (TICT) conformations of the pyrrole and phenyl or cyanophenyl groups. The experimental ICT dipole moment of PP4C has a value in between the theoretical results for mue(PICT) and mue(TICT), whereas the data for PP tend to favour the TICT configuration. It appears that in the LE state of PP and PP4M a negative charge remains on the pyrrole moiety, whereas a charge reversal takes place for the LE state of PP3C and the ICT state of PP, PP4C and PP3C.
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Affiliation(s)
- Toshitada Yoshihara
- Max-Planck-Institut für biophysikalische Chemie, Spektroskopie und Photochemische Kinetik, 37070 Göttingen, Germany
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28
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Belau L, Haas Y, Rettig W. Jet cooled spectra of pyrrolobenzene and of pyrrolobenzonitrile: the nature of the excited states. Chem Phys Lett 2002. [DOI: 10.1016/s0009-2614(02)01316-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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29
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Zilberg S, Haas Y. The Nature of the Intramolecular Charge Transfer Excited State in p-Pyrrolocyanobenzene (PBN) and Other Derivatives of Benzene Substituted by Electron Donor and Acceptor Groups. J Phys Chem A 2001. [DOI: 10.1021/jp012573j] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shmuel Zilberg
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem, Israel 91904
| | - Yehuda Haas
- Department of Physical Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University of Jerusalem, Jerusalem, Israel 91904
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30
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Fujiwara T, Fujimura Y, Kajimoto O. 9,9′-Bianthryl and its van der Waals complexes studied by rotational coherence spectroscopy: Structure and excited state dynamics. J Chem Phys 2000. [DOI: 10.1063/1.1288518] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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31
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Proppe B, Merchán M, Serrano-Andrés L. Theoretical Study of the Twisted Intramolecular Charge Transfer in 1-Phenylpyrrole. J Phys Chem A 2000. [DOI: 10.1021/jp993627g] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Boris Proppe
- Institut für Chemie-Physikalische und Theoretische Chemie, Freie Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany
| | - Manuela Merchán
- Departamento de Química Física, Universitat de València, Dr. Moliner 50, Burjassot, E-46100 Valencia, Spain
| | - Luis Serrano-Andrés
- Department of Theoretical Chemistry, Chemical Centre, P.O. Box 124, S-221 00 Lund, Sweden
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32
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Pirowska K, Parusel A, Najbar J, Kolek P, Gajdek P. The LIF excitation spectra of jet-cooled 3-aminobiphenyl. Chem Phys Lett 1999. [DOI: 10.1016/s0009-2614(99)00808-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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33
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Tsuji T, Hayashi Y, Hamabe H, Kawakami H, Mori A, Nishimura Y, Sekiya H. The electronic spectra of jet-cooled 5-phenyltropolone: Phenyl torsion and its effect on proton tunneling. J Chem Phys 1999. [DOI: 10.1063/1.478757] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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