1
|
Anstöter CS, Verlet JRR. A Hückel Model for the Excited-State Dynamics of a Protein Chromophore Developed Using Photoelectron Imaging. Acc Chem Res 2022; 55:1205-1213. [PMID: 35172580 PMCID: PMC9084545 DOI: 10.1021/acs.accounts.1c00780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Chemistry can be described as the movement of nuclei within molecules and the concomitant instantaneous change in electronic structure. This idea underpins the central chemical concepts of potential energy surfaces and reaction coordinates. To experimentally capture such chemical change therefore requires methods that can probe both the nuclear and electronic structure simultaneously and on the time scale of atomic motion. In this Account, we show how time-resolved photoelectron imaging can do exactly this and how it can be used to build a detailed and intuitive understanding of the electronic structure and excited-state dynamics of chromophores. The chromophore of the photoactive yellow protein (PYP) is used as a case study. This chromophore contains a para-substituted phenolate anion, where the substituent, R, can be viewed as an acrolein derivative. It is shown that the measured photoelectron angular distribution can be directly related to the electronic structure of the para-substituted phenolate anion. By incrementally considering differing R groups, it is also shown that these photoelectron angular distributions are exquisitely sensitive to the conformational flexibility of R and that when R contains a π-system the excited states of the chromophore can be viewed as a linear combination of the π* molecular orbitals on the phenolate (πPh*) and the R substituent (πR*). Such Hückel treatment shows that the S1 state of the PYP chromophore has predominantly πR* character and that it is essentially the same as the chromophore of the green fluorescent protein (GFP). The S1 excited-state dynamics of the PYP chromophore probed by time-resolved photoelectron imaging clearly reveals both structural (nuclear) dynamics through the energy spectrum and electronic dynamics through the photoelectron angular distributions. Both motions can be accurately assigned using quantum chemical calculations, and these are consistent with the intuitive Hückel treatment presented. The photoactive protein chromophores considered here are examples of where a chemists' intuitive Hückel view for ground-state chemistry appears to be transferable to the prediction of photochemical excited-state reactivity. While elegant and insightful, such models have limitations, including nonadiabatic dynamics, which is present in a related PYP chromophore, where a fraction of the S1 state population forms a nonvalence (dipole-bound) state of the anion.
Collapse
Affiliation(s)
- Cate S. Anstöter
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Jan R. R. Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| |
Collapse
|
2
|
Dowek D, Decleva P. Trends in angle-resolved molecular photoelectron spectroscopy. Phys Chem Chem Phys 2022; 24:24614-24654. [DOI: 10.1039/d2cp02725a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this perspective article, main trends of angle-resolved molecular photoelectron spectroscopy in the laboratory up to the molecular frame, in different regimes of light-matter interactions, are highlighted with emphasis on foundations and most recent applications.
Collapse
Affiliation(s)
- Danielle Dowek
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d’Orsay, 91405 Orsay, France
| | - Piero Decleva
- CNR IOM and Dipartimento DSCF, Università di Trieste, Trieste, Italy
| |
Collapse
|
3
|
Woodhouse JL, Henley A, Lewin R, Ward JM, Hailes HC, Bochenkova AV, Fielding HH. A photoelectron imaging study of the deprotonated GFP chromophore anion and RNA fluorescent tags. Phys Chem Chem Phys 2021; 23:19911-19922. [PMID: 34474467 DOI: 10.1039/d1cp01901e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Green fluorescent protein (GFP), together with its family of variants, is the most widely used fluorescent protein for in vivo imaging. Numerous spectroscopic studies of the isolated GFP chromophore have been aimed at understanding the electronic properties of GFP. Here, we build on earlier work [A. V. Bochenkova, C. Mooney, M. A. Parkes, J. Woodhouse, L. Zhang, R. Lewin, J. M. Ward, H. Hailes, L. H. Andersen and H. H. Fielding, Chem. Sci., 2017, 8, 3154] investigating the impact of fluorine and methoxy substituents that have been employed to tune the electronic structure of the GFP chromophore for use as fluorescent RNA tags. We present photoelectron spectra following photoexcitation over a broad range of wavelengths (364-230 nm) together with photoelectron angular distributions following photoexcitation at 364 nm, which are interpreted with the aid of quantum chemistry calculations. The results support the earlier high-level quantum chemistry calculations that predicted how fluorine and methoxy substituents tune the electronic structure and we find evidence to suggest that the methoxy substituents enhance internal conversion, most likely from the 2ππ* state which has predominantly Feshbach resonance character, to the 1ππ* state.
Collapse
Affiliation(s)
- Joanne L Woodhouse
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Alice Henley
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Ross Lewin
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - John M Ward
- The Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Gower Street, London WC1E 6BT, UK
| | - Helen C Hailes
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | | | - Helen H Fielding
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| |
Collapse
|
4
|
Anstöter CS, Verlet JRR. Modeling the Photoelectron Angular Distributions of Molecular Anions: Roles of the Basis Set, Orbital Choice, and Geometry. J Phys Chem A 2021; 125:4888-4895. [PMID: 34042462 DOI: 10.1021/acs.jpca.1c03379] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A study investigating the effect of the basis set, orbital choice, and geometry on the modeling of photoelectron angular distributions (PADs) of molecular anions is presented. Experimental and modeled PADs for a number of molecular anions, including both closed- and open-shell systems, are considered. Guidelines are suggested for chemists who wish to design calculations to capture the correct chemical physics of the anisotropy of photodetachment, while balancing the computational cost associated with larger molecular anions.
Collapse
Affiliation(s)
- Cate S Anstöter
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| |
Collapse
|
5
|
Gozem S, Krylov AI. The
ezSpectra
suite: An easy‐to‐use toolkit for spectroscopy modeling. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2021. [DOI: 10.1002/wcms.1546] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Samer Gozem
- Department of Chemistry Georgia State University Atlanta Georgia USA
| | - Anna I. Krylov
- Department of Chemistry University of Southern California Los Angeles California USA
| |
Collapse
|
6
|
Anstöter CS, Verlet JRR. Photoelectron imaging of the SO 3 anion: vibrational resolution in photoelectron angular distributions*. Mol Phys 2021. [DOI: 10.1080/00268976.2020.1821921] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
7
|
Anstöter CS, Matsika S. Understanding the Interplay between the Nonvalence and Valence States of the Uracil Anion upon Monohydration. J Phys Chem A 2020; 124:9237-9243. [DOI: 10.1021/acs.jpca.0c07407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Cate S. Anstöter
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Spiridoula Matsika
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| |
Collapse
|
8
|
Anstöter CS, Verlet JRR. Gas-Phase Synthesis and Characterization of the Methyl-2,2-dicyanoacetate Anion Using Photoelectron Imaging and Dipole-Bound State Autodetachment. J Phys Chem Lett 2020; 11:6456-6462. [PMID: 32687376 DOI: 10.1021/acs.jpclett.0c02036] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The methyl-2,2-dicyanoacetate anion is synthesized in an electrospray ionization source through a gas-phase reaction involving tetracyanoethylene and methanol. Photoelectron imaging is used to determine the isomeric form of the product. The photoelectron spectra and angular distributions are consistent with only a single isomer. Additionally, mode-specific vibrational autodetachment is observed. This can be correlated with the emission from a photoexcited dipole-bound state by considering the IR spectrum of the neutral molecule, adding further confirmation of the isomeric form and providing a binding energy of the dipole-bound state. Our experiments show how conventional photoelectron imaging can be used to determine detailed information about gas-phase reaction products.
Collapse
Affiliation(s)
- Cate S Anstöter
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| |
Collapse
|
9
|
Anstöter CS, Curchod BFE, Verlet JRR. Geometric and electronic structure probed along the isomerisation coordinate of a photoactive yellow protein chromophore. Nat Commun 2020; 11:2827. [PMID: 32499507 PMCID: PMC7272410 DOI: 10.1038/s41467-020-16667-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 05/15/2020] [Indexed: 01/29/2023] Open
Abstract
Understanding the connection between the motion of the nuclei in a molecule and the rearrangement of its electrons lies at the heart of chemistry. While many experimental methods have been developed to probe either the electronic or the nuclear structure on the timescale of atomic motion, very few have been able to capture both these changes in concert. Here, we use time-resolved photoelectron imaging to probe the isomerisation coordinate on the excited state of an isolated model chromophore anion of the photoactive yellow protein. By probing both the electronic structure changes as well as nuclear dynamics, we are able to uniquely measure isomerisation about a specific bond. Our results demonstrate that the photoelectron signal dispersed in time, energy and angle combined with calculations can track the evolution of both electronic and geometric structure along the adiabatic state, which in turn defines that chemical transformation. Resolving concerted nuclear and electronic motion in real-time is a primary goal in chemistry. The authors monitor nuclear and valence electronic dynamics in the excited state single-bond isomerisation of a chromophore of photoactive yellow protein, using time-resolved photoelectron imaging and electronic structure calculations.
Collapse
Affiliation(s)
- Cate S Anstöter
- Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | | | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham, DH1 3LE, UK.
| |
Collapse
|
10
|
Verlet JRR, Anstöter CS, Bull JN, Rogers JP. Role of Nonvalence States in the Ultrafast Dynamics of Isolated Anions. J Phys Chem A 2020; 124:3507-3519. [PMID: 32233436 PMCID: PMC7212518 DOI: 10.1021/acs.jpca.0c01260] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Nonvalence states
of neutral molecules (Rydberg states) play important
roles in nonadiabatic dynamics of excited states. In anions, such
nonadiabatic transitions between nonvalence and valence states have
been much less explored even though they are believed to play important
roles in electron capture and excited state dynamics of anions. The
aim of this Feature Article is to provide an overview of recent experimental
observations, based on time-resolved photoelectron imaging, of valence
to nonvalence and nonvalence to valence transitions in anions and
to demonstrate that such dynamics may be commonplace in the excited
state dynamics of molecular anions and cluster anions.
Collapse
Affiliation(s)
- Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Cate S Anstöter
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Joshua P Rogers
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| |
Collapse
|
11
|
Castellani ME, Anstöter CS, Verlet JRR. On the stability of a dipole-bound state in the presence of a molecule. Phys Chem Chem Phys 2019; 21:24286-24290. [PMID: 31663558 DOI: 10.1039/c9cp04942h] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dipole-bound states (DBSs) are diffuse non-valence molecular orbitals of anions where the electron is bound by the permanent dipole moment of the neutral core. Here, an experimental study of the stability of such orbitals under the influence of a perturbing molecular alkyl chain is presented. Photodetachment action and photoelectron imaging spectroscopy of five para-substituted phenolate anions with progressively longer alkyl chains show that the DBS survives in all cases, suggesting that the perturbation of the orbital is not critical to the existence of the DBS.
Collapse
|
12
|
Woodhouse JL, Henley A, Parkes MA, Fielding HH. Photoelectron Imaging and Quantum Chemistry Study of Phenolate, Difluorophenolate, and Dimethoxyphenolate Anions. J Phys Chem A 2019; 123:2709-2718. [PMID: 30848907 DOI: 10.1021/acs.jpca.8b11121] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joanne L. Woodhouse
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AH, U.K
| | - Alice Henley
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AH, U.K
| | - Michael A. Parkes
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AH, U.K
| | - Helen H. Fielding
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AH, U.K
| |
Collapse
|
13
|
Rogers JP, Anstöter CS, Bull JN, Curchod BFE, Verlet JRR. Photoelectron Spectroscopy of the Hexafluorobenzene Cluster Anions: (C 6F 6) n- ( n = 1-5) and I -(C 6F 6). J Phys Chem A 2019; 123:1602-1612. [PMID: 30694676 DOI: 10.1021/acs.jpca.8b11627] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Frequency-resolved (2D) photoelectron (PE) spectra of the anionic clusters (C6F6) n-, for n = 1-5, and time-resolved PE spectra of I-C6F6 are presented using a newly built instrument and supported by electronic structure calculations. From the 2D PE spectra, the vertical detachment energy (VDE) of C6F6- was measured to be 1.60 ± 0.01 eV, and the adiabatic detachment energy (ADE) was ≤0.70 eV. The PE spectra also contain fingerprints of resonance dynamics over certain photon energy ranges, in agreement with the calculations. An action spectrum over the lowest resonance is also presented. The 2D spectra of (C6F6) n- show that the cluster can be described as C6F6-(C6F6) n-1. The VDE increases linearly (200 ± 20 meV n-1) due to the stabilizing influence on the anion of the solvating C6F6 molecules. For I-C6F6, action spectra of the absorption just below both detachment channels are presented. Time-resolved PE spectra of I-C6F6 excited at 3.10 eV and probed at 1.55 eV reveal a short-lived nonvalence state of C6F6- that coherently evolves into the valence ground state of the anion and induces vibrational motion along a specific buckling coordinate. Electronic structure calculations along the displacement of this mode show that at the extreme buckling angle the probe can access an excited state of the anion that is bound at that geometry but adiabatically unbound. Hence, slow electrons are emitted and show dynamics that predominantly probe the outer-turning point of the motion. A PE spectrum taken at t = 0 contains a vibrational structure assigned to a specific Raman- or IR-active mode of C6F6.
Collapse
Affiliation(s)
- Joshua P Rogers
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - Cate S Anstöter
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - James N Bull
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - Basile F E Curchod
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - Jan R R Verlet
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| |
Collapse
|
14
|
Affiliation(s)
- Alice Henley
- Department of Chemistry, University College London, London, UK
| | | |
Collapse
|
15
|
Rogers JP, Anstöter CS, Verlet JRR. Evidence of Electron Capture of an Outgoing Photoelectron Wave by a Nonvalence State in (C 6F 6) n. J Phys Chem Lett 2018; 9:2504-2509. [PMID: 29694047 DOI: 10.1021/acs.jpclett.8b00739] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Frequency-resolved photoelectron spectra are presented for (C6F6) n- with n = 1-5 that show that C6F6- is solvated by neutral C6F6 molecules. Direct photodetachment channels of C6F6- are observed for all n, leaving the neutral in the S0 ground state or triplet states, T1 and T2. For n ≥ 2, an additional indirect electron loss channel is observed when the triplet-state channels open. This indirect emission appears to arise from the electron capture of the outgoing photoelectron s-wave by a neutral solvent molecule through an anion nonvalence state. The same process is not observed for the S0 detachment channel because the outgoing electron wave is predominantly a p-wave. Our results show that anion nonvalence states can act as electron-accepting states in cluster environments and can be viewed as precursor states for diffuse states of liquid C6F6.
Collapse
Affiliation(s)
- Joshua P Rogers
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - Cate S Anstöter
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| | - Jan R R Verlet
- Department of Chemistry , Durham University , Durham DH1 3LE , United Kingdom
| |
Collapse
|
16
|
Nelson DJ, Oliveira AM, Lineberger WC. Anion photoelectron spectroscopy of deprotonated indole and indoline. J Chem Phys 2018; 148:064307. [DOI: 10.1063/1.5003978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Daniel J. Nelson
- JILA and The Department of Chemistry and Biochemistry, University of Colorado Boulder, 440 UCB, Boulder, Colorado 80309, USA
| | - Allan M. Oliveira
- JILA and The Department of Chemistry and Biochemistry, University of Colorado Boulder, 440 UCB, Boulder, Colorado 80309, USA
| | - W. Carl Lineberger
- JILA and The Department of Chemistry and Biochemistry, University of Colorado Boulder, 440 UCB, Boulder, Colorado 80309, USA
| |
Collapse
|
17
|
Anstöter CS, Gartmann TE, Stanley LH, Bochenkova AV, Verlet JRR. Electronic structure of the para-dinitrobenzene radical anion: a combined 2D photoelectron imaging and computational study. Phys Chem Chem Phys 2018; 20:24019-24026. [DOI: 10.1039/c8cp04877k] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
2D photoelectron spectroscopy combined with high-level ab initio calculations provides insights into the dissociative electron attachment of para-dinitrobenzene.
Collapse
Affiliation(s)
- Cate S. Anstöter
- Department of Chemistry
- Durham University
- Durham DH1 3LE
- UK
- Department of Chemistry
| | | | | | | | | |
Collapse
|
18
|
Anstöter CS, Dean CR, Verlet JRR. Chromophores of chromophores: a bottom-up Hückel picture of the excited states of photoactive proteins. Phys Chem Chem Phys 2017; 19:29772-29779. [DOI: 10.1039/c7cp05766k] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Many photoactive proteins contain chromophores based on para-substituted phenolate anions which are an essential component of their electronic structure.
Collapse
|