1
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Diop M, El-Hayek M, Attard J, Muhieddine A, Veremeienko V, Soorkia S, Carbonnière P, de la Lande A, Soep B, Shafizadeh N. Chlorophyll and pheophytin protonated and deprotonated ions: Observation and theory. J Chem Phys 2023; 159:194308. [PMID: 37987519 DOI: 10.1063/5.0174351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 10/30/2023] [Indexed: 11/22/2023] Open
Abstract
Pheophytin a and chlorophyll a have been investigated by electrospray mass spectrometry in the positive and negative modes, in view of the importance of the knowledge of their properties in photosynthesis. Pheophytin and chlorophyll are both observed intensely in the protonated mode, and their main fragmentation route is the loss of their phytyl chain. Pheophytin is observed intact in the negative mode, while under collisions, it is primarily cleaved beyond the phytyl chain and loses the attaching propionate group. Chlorophyll is not detected in normal conditions in the negative mode, but addition of methanol solvent molecule is detected. Fragmentation of this adduct primarily forms a product (-30 amu) that dissociates into dephytyllated deprotonated chlorophyll. Semi-empirical molecular dynamics calculations show that the phytyl chain is unfolded from the chlorin cycle in pheophytin a and folded in chlorophyll a. Density functional theory calculations have been conducted to locate the charges on protonated and deprotonated pheophytin a and chlorophyll a and have found the major location sites that are notably more stable in energy by more than 0.5 eV than the others. The deprotonation site is found identical for pheophytin a and the chlorophyll a-methanol adduct. This is in line with experiment and calculation locating the addition of methanol on a double bond of deprotonated chlorophyll a.
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Affiliation(s)
- M Diop
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d' Orsay, 91405 Orsay, France
| | - M El-Hayek
- Université Paris Saclay, CNRS, Institut de Chimie Physique, UMR 8000, 91405 Orsay, France
| | - J Attard
- Université Paris Saclay, CNRS, Institut de Chimie Physique, UMR 8000, 91405 Orsay, France
- Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Pau, France
| | - A Muhieddine
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d' Orsay, 91405 Orsay, France
| | - V Veremeienko
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - S Soorkia
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d' Orsay, 91405 Orsay, France
| | - Ph Carbonnière
- Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Pau, France
| | - A de la Lande
- Université Paris Saclay, CNRS, Institut de Chimie Physique, UMR 8000, 91405 Orsay, France
| | - B Soep
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d' Orsay, 91405 Orsay, France
| | - N Shafizadeh
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d' Orsay, 91405 Orsay, France
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2
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Förster A, Visscher L. Quasiparticle Self-Consistent GW-Bethe-Salpeter Equation Calculations for Large Chromophoric Systems. J Chem Theory Comput 2022; 18:6779-6793. [PMID: 36201788 PMCID: PMC9648197 DOI: 10.1021/acs.jctc.2c00531] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The GW-Bethe–Salpeter equation
(BSE) method
is promising for calculating the low-lying excitonic states of molecular
systems. However, so far it has only been applied to rather small
molecules and in the commonly implemented diagonal approximations
to the electronic self-energy, it depends on a mean-field starting
point. We describe here an implementation of the self-consistent and
starting-point-independent quasiparticle self-consistent (qsGW)-BSE approach, which is suitable for calculations on
large molecules. We herein show that eigenvalue-only self-consistency
can lead to an unfaithful description of some excitonic states for
chlorophyll dimers while the qsGW-BSE vertical excitation
energies (VEEs) are in excellent agreement with spectroscopic experiments
for chlorophyll monomers and dimers measured in the gas phase. Furthermore,
VEEs from time-dependent density functional theory calculations tend
to disagree with experimental values and using different range-separated
hybrid (RSH) kernels does change the VEEs by up to 0.5 eV. We use
the new qsGW-BSE implementation to calculate the
lowest excitation energies of the six chromophores of the photosystem
II (PSII) reaction center (RC) with nearly 2000 correlated electrons.
Using more than 11,000 (6000) basis functions, the calculation could
be completed in less than 5 (2) days on a single modern compute node.
In agreement with previous TD-DFT calculations using RSH kernels on
models that also do not include environmental effects, our qsGW-BSE calculations only yield states with local characters
in the low-energy spectrum of the hexameric complex. Earlier works
with RSH kernels have demonstrated that the protein environment facilitates
the experimentally observed interchromophoric charge transfer. Therefore,
future research will need to combine correlation effects beyond TD-DFT
with an explicit treatment of environmental electrostatics.
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Affiliation(s)
- Arno Förster
- Theoretical Chemistry, Vrije Universiteit, De Boelelaan 1083, NL-1081 HVAmsterdam, The Netherlands
| | - Lucas Visscher
- Theoretical Chemistry, Vrije Universiteit, De Boelelaan 1083, NL-1081 HVAmsterdam, The Netherlands
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3
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Li F, Cao J, Wang Z, Liao X, Hu X, Zhang Y. Dual aggregation in ground state and ground-excited state induced by high concentrations contributes to chlorophyll stability. Food Chem 2022; 383:132447. [PMID: 35182875 DOI: 10.1016/j.foodchem.2022.132447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 01/07/2022] [Accepted: 02/10/2022] [Indexed: 11/16/2022]
Abstract
Chlorophyll (Chl) has great application potential in food colouring and nutritional supplementation. Since Chl is easily degraded, stability protection is vital to its application. Herein, a dual aggregation mechanism induced by high concentrations to improve Chl stability was proposed. As a result, the Chl retention at high concentrations increased to 323.92% of that at low concentrations. To explain aggregation, the Chl dimer was observed by atomic force microscopy, and a stable structural model of the Chl a "sandwich" dimer was established. It was proven that Chl dimer stability was dominated by van der Waals (vdW) interactions, while monomer orientation during aggregation was dominated by electrostatic interactions. Charge transfer (CT) was also shown to be a key interaction in the dimer. Excitation at 393 nm was first proposed for CT identification. This research hopes to provide new ideas for the design of food ingredients in human health promotion.
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Affiliation(s)
- Fangwei Li
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, People's Republic of China; National Engineering Research Center for Fruit and Vegetable Processing, Ministry of Science and Technology, Beijing 100083, People's Republic of China
| | - Jiarui Cao
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, People's Republic of China; National Engineering Research Center for Fruit and Vegetable Processing, Ministry of Science and Technology, Beijing 100083, People's Republic of China
| | - Zhenhao Wang
- College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, People's Republic of China
| | - Xiaojun Liao
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, People's Republic of China; National Engineering Research Center for Fruit and Vegetable Processing, Ministry of Science and Technology, Beijing 100083, People's Republic of China
| | - Xiaosong Hu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, People's Republic of China; National Engineering Research Center for Fruit and Vegetable Processing, Ministry of Science and Technology, Beijing 100083, People's Republic of China
| | - Yan Zhang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, People's Republic of China; National Engineering Research Center for Fruit and Vegetable Processing, Ministry of Science and Technology, Beijing 100083, People's Republic of China.
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4
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Gruber E, Teiwes R, Kjær C, Brøndsted Nielsen S, Andersen LH. Tuning fast excited-state decay by ligand attachment in isolated chlorophyll a. Phys Chem Chem Phys 2021; 24:149-155. [PMID: 34901981 DOI: 10.1039/d1cp04356k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Excited-state dynamics plays a key role for light harvesting and energy transport in photosynthetic proteins but it is nontrivial to separate the intrinsic photophysics of the light-absorbers (chlorophylls) from interactions with the protein matrix. Here we study chlorophyll a (4-coordinate complex) and axially ligated chlorophyll a (5-coordinate complex) isolated in vacuo applying mass spectrometry to shed light on the intrinsic dynamics in the absence of nearby chlorophylls, carotenoids, amino acids, and water molecules. The 4-coordinate complexes are tagged by quaternary ammonium ions while the charge is provided by a formate ligand in the case of 5-coordinate complexes. Regardless of excitation to the Soret band or the Q band, a fast ps decay is observed, which is ascribed to the decay of the lowest excited singlet state either by intersystem crossing (ISC) to nearby triplet states or by excited-state relaxation on the excited-state potential-energy surface. The lifetime of the first excited state is 15 ps with Mg2+ at the chlorophyll center, but only 1.7 ps when formate is attached to Mg2+. When the Soret band is excited, an initial sup-ps relaxation is observed which is ascribed to fast internal conversion to the first excited state. With respect to ISC, two factors seem to play a role for the reduced lifetime of the formate-chlorophyll complex: (i) The Mg ion is pulled out of the porphyrin plane thus reducing the symmetry of the chromophore, and (ii) the first excited state (Q band) and T3 are tuned almost into resonance by the ligand, which increases the singlet-triplet mixing.
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Affiliation(s)
- Elisabeth Gruber
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000C, Denmark.
| | - Ricky Teiwes
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000C, Denmark.
| | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000C, Denmark.
| | | | - Lars H Andersen
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000C, Denmark.
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5
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Hansen K. DECAY DYNAMICS IN MOLECULAR BEAMS. MASS SPECTROMETRY REVIEWS 2021; 40:725-740. [PMID: 32362024 DOI: 10.1002/mas.21630] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 04/07/2020] [Indexed: 06/11/2023]
Abstract
The phenomenon of power law decays in molecular beams is reviewed. The transition from a canonical to a microcanonical description of the decay is analyzed, and the appearance of the power law decay derived. Deviations from a power law often contain information on parallel competing processes. This is illustrated with examples where thermal radiation or dark unimolecular channels are the competing processes. Also corrections to the power law due to finite heat capacities and from nonideal energy distributions are derived. Finally, the consequences for the interpretation of action spectroscopy data are reviewed. © 2020 The Authors. Mass Spectrometry Reviews published by Wiley Periodicals, Inc. Mass Spec Rev.
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Affiliation(s)
- Klavs Hansen
- Department of Physics, School of Science, Center for Joint Quantum Studies, Tianjin University, 92 Weijin Road, 300072, Tianjin, China
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6
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Giacomozzi L, Kjær C, Brøndsted Nielsen S, Ashworth EK, Bull JN, Stockett MH. Non-statistical fragmentation in photo-activated flavin mononucleotide anions. J Chem Phys 2021; 155:044305. [PMID: 34340366 DOI: 10.1063/5.0056415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The spectroscopy and photo-induced dissociation of flavin mononucleotide anions in vacuo are investigated over the 300-500 nm wavelength range. Comparison of the dependence of fragment ion yields as a function of deposited photon energy with calculated dissociation energies and collision-induced dissociation measurements performed under single-collision conditions suggests that a substantial fraction of photo-activated ions decompose through non-statistical fragmentation pathways. Among these pathways is the dominant photo-induced fragmentation channel, the loss of a fragment identified as formylmethylflavin. The fragment ion specific action spectra reveal electronic transition energies close to those for flavins in solution and previously published gas-phase measurements, although the photo-fragment yield upon excitation of the S2 ← S0 transition appears to be suppressed.
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Affiliation(s)
| | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | | | - Eleanor K Ashworth
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - James N Bull
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Mark H Stockett
- Department of Physics, Stockholm University, Stockholm, Sweden
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7
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Ultrafast spectroscopic investigation of discrete co-assemblies of a Zn-porphyrin–polymer conjugate with a hexapyridyl template. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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8
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Furlan C, Berenbeim JA, Dessent CEH. Photoproducts of the Photodynamic Therapy Agent Verteporfin Identified via Laser Interfaced Mass Spectrometry. Molecules 2020; 25:molecules25225280. [PMID: 33198255 PMCID: PMC7696214 DOI: 10.3390/molecules25225280] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/08/2020] [Accepted: 11/09/2020] [Indexed: 12/12/2022] Open
Abstract
Verteporfin, a free base benzoporphyrin derivative monoacid ring A, is a photosensitizing drug for photodynamic therapy (PDT) used in the treatment of the wet form of macular degeneration and activated by red light of 689 nm. Here, we present the first direct study of its photofragmentation channels in the gas phase, conducted using a laser interfaced mass spectrometer across a broad photoexcitation range from 250 to 790 nm. The photofragmentation channels are compared with the collision-induced dissociation (CID) products revealing similar dissociation pathways characterized by the loss of the carboxyl and ester groups. Complementary solution-phase photolysis experiments indicate that photobleaching occurs in verteporfin in acetonitrile; a notable conclusion, as photoinduced activity in Verteporfin was not thought to occur in homogenous solvent conditions. These results provide unique new information on the thermal break-down products and photoproducts of this light-triggered drug.
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9
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Preciado-Rivas MR, Mowbray DJ, Lyon K, Larsen AH, Milne BF. Optical excitations of chlorophyll a and b monomers and dimers. J Chem Phys 2019; 151:174102. [PMID: 31703510 DOI: 10.1063/1.5121721] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A necessary first step in the development of technologies such as artificial photosynthesis is understanding the photoexcitation process within the basic building blocks of naturally occurring light harvesting complexes (LHCs). The most important of these building blocks in biological LHCs such as LHC II from green plants are the chlorophyll a (Chl a) and chlorophyll b (Chl b) chromophores dispersed throughout the protein matrix. However, efforts to describe such systems are still hampered by the lack of computationally efficient and accurate methods that are able to describe optical absorption in large biomolecules. In this work, we employ a highly efficient linear combination of atomic orbitals (LCAOs) to represent the Kohn-Sham (KS) wave functions at the density functional theory (DFT) level and perform time-dependent density functional theory (TDDFT) calculations in either the reciprocal space and frequency domain (LCAO-TDDFT-k-ω) or real space and time domain (LCAO-TDDFT-r-t) of the optical absorption spectra of Chl a and b monomers and dimers. We find that our LCAO-TDDFT-k-ω and LCAO-TDDFT-r-t calculations reproduce results obtained with a plane-wave (PW) representation of the KS wave functions (PW-TDDFT-k-ω) but with a significant reduction in computational effort. Moreover, by applying the Gritsenko, van Leeuwen, van Lenthe, and Baerends solid and correlation derivative discontinuity correction Δx to the KS eigenenergies, with both LCAO-TDDFT-k-ω and LCAO-TDDFT-r-t methods, we are able to semiquantitatively reproduce the experimentally measured photoinduced dissociation results. This work opens the path to first principles calculations of optical excitations in macromolecular systems.
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Affiliation(s)
| | - Duncan John Mowbray
- School of Physical Sciences and Nanotechnology, Yachay Tech University, Urcuquí 100119, Ecuador
| | - Keenan Lyon
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Ask Hjorth Larsen
- Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, Departamento de Física de Materiales, Universidad del País Vasco UPV/EHU, E-20018 San Sebastián, Spain
| | - Bruce Forbes Milne
- Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, Departamento de Física de Materiales, Universidad del País Vasco UPV/EHU, E-20018 San Sebastián, Spain
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10
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Gruber E, Kjaer C, Nielsen SB, Andersen LH. Intrinsic Photophysics of Light-harvesting Charge-tagged Chlorophyll a and b Pigments. Chemistry 2019; 25:9153-9158. [PMID: 31095797 DOI: 10.1002/chem.201901786] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 05/15/2019] [Indexed: 12/20/2022]
Abstract
Chlorophylls a and b (Chla/b) are responsible for light-harvesting by photosynthetic proteins in plants. They display broad absorption in the visible region with multiple bands, due to the asymmetry of the macrocycle and strong vibronic coupling. Their photophysics relies on the microenvironment, with regard to transition energies as well as quenching of triplet states. Here, we firmly establish the splitting of the Q and Soret bands into x- and y- polarized bands for the isolated molecules in vacuo, and resolve vibronic features. Storage-ring experiments reveal that dissociation of photoexcited charge-tagged complexes occurs over several milliseconds, but with two different time constants. A fast decay is ascribed to dissociation after internal conversion and a slow decay to the population of a triplet state that acts as a bottleneck. Support for the latter is provided by pump-probe experiments, where a second laser pulse probes the long-lived triplet state.
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Affiliation(s)
| | - Christina Kjaer
- Department of Physics and Astronomy, Aarhus University, Denmark
| | | | - Lars H Andersen
- Department of Physics and Astronomy, Aarhus University, Denmark
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11
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Chojecki M, Rutkowska-Zbik D, Korona T. Dimerization Behavior of Methyl Chlorophyllide a as the Model of Chlorophyll a in the Presence of Water Molecules-Theoretical Study. J Chem Inf Model 2019; 59:2123-2140. [PMID: 30998013 DOI: 10.1021/acs.jcim.8b00984] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A dimerization of methyl chlorophyllide a molecules and a role of water in stabilization and properties of methyl chlorophyllide a dimers were studied by means of symmetry-adapted perturbation theory (SAPT), functional-group SAPT (F-SAPT), density-functional theory (DFT), and time-dependent DFT approaches. The quantification of various types of interactions, such as π-π stacking, coordinative, and hydrogen bonding by applying the F-SAPT energy decomposition scheme shows the major role of the magnesium atom and the pheophytin macrocycle in the stability of the complex. The examination of interaction energy components with respect to a mutual orientation of monomers and in the presence or absence of water molecules reveals that the dispersion energy is the main binding factor of the interaction, while water molecules tend to weaken the attraction between methyl chlorophyllide a species. The dimerization can be seen in computed UV-vis spectra, and results in a doubling of the lowest peaks, as compared to the monomer spectrum, and in an intensity rise of the lowest 1.8 and 2.4 eV peaks at a cost of the 3.5 eV peaks for the majority of dimer configurations. The complexation of water has little effect on the peaks' position; however, it affects the overall shape of simulated spectra through changes in peak intensities, which is strongly dependent on the structure of the complex. The VCD spectra for the dimers show several characteristic features attributed to the interaction of substituting groups and/or water ligand attached to macrocycle groups belonging to different monomers. VCD is sensitive to the type of the formed dimer, but not to the number of water molecules it contains. This and several other features, as well as the differential UV-vis spectra, may serve as the indicator of the presence of a given dimer structure in the experiment.
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Affiliation(s)
- Michał Chojecki
- Faculty of Chemistry , University of Warsaw , ul. Pasteura 1 , 02-093 Warsaw , Poland
| | - Dorota Rutkowska-Zbik
- Jerzy Haber Institute of Catalysis and Surface Chemistry , Polish Academy of Sciences , ul. Niezapominajek 8 , 30-239 Cracow , Poland
| | - Tatiana Korona
- Faculty of Chemistry , University of Warsaw , ul. Pasteura 1 , 02-093 Warsaw , Poland
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12
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Suomivuori CM, Fliegl H, Starikov EB, Balaban TS, Kaila VRI, Sundholm D. Absorption shifts of diastereotopically ligated chlorophyll dimers of photosystem I. Phys Chem Chem Phys 2019; 21:6851-6858. [DOI: 10.1039/c9cp00616h] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Excited-state properties of α- and β-ligated chlorophyll dimers of photosystem I were studied at ab initio correlated levels of theory.
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Affiliation(s)
| | - Heike Fliegl
- Hylleraas Centre for Quantum Molecular Sciences
- Department of Chemistry
- University of Oslo
- 0315 Oslo
- Norway
| | - Evgeni B. Starikov
- Graduate School of System Informatics
- Department of Computational Science
- Kobe 657-8501
- Japan
| | - T. Silviu Balaban
- Aix Marseille Univ
- CNRS
- Centrale Marseille
- UMR 7313
- 13397 Marseille, Cedex 20
| | - Ville R. I. Kaila
- Department of Chemistry
- Technical University of Munich
- D-85747 Garching
- Germany
| | - Dage Sundholm
- Department of Chemistry
- University of Helsinki
- Finland
- Centre for Advanced Study at the Norwegian Academy of Science and Letters
- N-0271 Oslo
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13
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Bull JN, Carrascosa E, Giacomozzi L, Bieske EJ, Stockett MH. Ion mobility action spectroscopy of flavin dianions reveals deprotomer-dependent photochemistry. Phys Chem Chem Phys 2018; 20:19672-19681. [PMID: 30014081 PMCID: PMC6063075 DOI: 10.1039/c8cp03244k] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Photo-induced proton transfer, deprotomer-dependent photochemistry, and intramolecular charge transfer in flavin anions are investigated using action spectroscopy.
The intrinsic optical properties and photochemistry of flavin adenine dinucleotide (FAD) dianions are investigated using a combination of tandem ion mobility spectrometry and action spectroscopy. Two principal isomers are observed, the more stable form being deprotonated on the isoalloxazine group and a phosphate (N-3,PO4 deprotomer), and the other on the two phosphates (PO4,PO4 deprotomer). Ion mobility data and electronic action spectra suggest that photo-induced proton transfer occurs from the isoalloxazine group to a phosphate group, converting the PO4,PO4 deprotomer to the N-3,PO4 deprotomer. Comparisons of the isomer selective action spectra of FAD dianions and flavin monoanions with solution spectra and gas-phase photodissociation action spectra suggests that solvation shifts the electronic absorption of the deprotonated isoalloxazine group to higher energy. This is interpreted as evidence for significant charge transfer in the lowest optical transition of deprotonated isoalloxazine. Overall, this work demonstrates that the site of deprotonation of flavin anions strongly affects their electronic absorptions and photochemistry.
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Affiliation(s)
- James N Bull
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Eduardo Carrascosa
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
| | | | - Evan J Bieske
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Mark H Stockett
- School of Chemistry, University of Melbourne, Melbourne, VIC 3010, Australia and Department of Physics, Stockholm University, Stockholm, Sweden.
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14
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Schneider E, Brendle K, Jäger P, Weis P, Kappes MM. Ion Mobility Measurements of Multianionic Metalloporphyrin Dimers: Structural Changes Induced by Countercation Exchange. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:1431-1441. [PMID: 29667165 DOI: 10.1007/s13361-018-1941-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 02/19/2018] [Accepted: 03/08/2018] [Indexed: 06/08/2023]
Abstract
We present gas-phase structures of dimers of MnIII and FeIII meso-tetra(4-sulfonatophenyl)porphyrin multianions with various amounts of sodium and hydrogen counterions. The structural assignments are achieved by combining mass spectrometry, ion mobility measurements, quantum chemical calculations, and trajectory method collision cross section calculations. For a common charge state, we observe significant topological variations in the dimer structures of [(MTPPS)2+nX](6-n)- (M=MnIII, FeIII; X=H, Na; n = 1-3) induced by replacing hydrogen counterions by sodium. For sodium, the dimer structures are much more compact, a finding that can be rationalized by the stronger interactions of the sodium cations with the anionic sulfonic acid groups of the porphyrins as compared to hydrogen. Graphical Abstract ᅟ.
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Affiliation(s)
- Erik Schneider
- Institute of Physical Chemistry, Karlsruhe Institute of Technology, 76131, Karlsruhe, Germany
| | - Katrina Brendle
- Institute of Physical Chemistry, Karlsruhe Institute of Technology, 76131, Karlsruhe, Germany
| | - Patrick Jäger
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
| | - Patrick Weis
- Institute of Physical Chemistry, Karlsruhe Institute of Technology, 76131, Karlsruhe, Germany.
| | - Manfred M Kappes
- Institute of Physical Chemistry, Karlsruhe Institute of Technology, 76131, Karlsruhe, Germany.
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany.
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15
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Jäger P, Brendle K, Schneider E, Kohaut S, Armbruster MK, Fink K, Weis P, Kappes MM. Photodissociation of Free Metalloporphyrin Dimer Multianions. J Phys Chem A 2018; 122:2974-2982. [PMID: 29490134 DOI: 10.1021/acs.jpca.8b00641] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Patrick Jäger
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Postfach 3630, 76021 Karlsruhe, Germany
| | - Katrina Brendle
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Erik Schneider
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Stephan Kohaut
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Postfach 3630, 76021 Karlsruhe, Germany
| | - Markus K. Armbruster
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Postfach 3630, 76021 Karlsruhe, Germany
| | - Karin Fink
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Postfach 3630, 76021 Karlsruhe, Germany
| | - Patrick Weis
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Manfred M. Kappes
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Postfach 3630, 76021 Karlsruhe, Germany
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
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16
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Stockett MH. Photo-induced proton-coupled electron transfer and dissociation of isolated flavin adenine dinucleotide mono-anions. Phys Chem Chem Phys 2018; 19:25829-25833. [PMID: 28745349 DOI: 10.1039/c7cp04068g] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The intrinsic optical absorption spectrum and photo-dissociation pathways of flavin adenine dinucleotide (FAD) mono-anions isolated in vacuo are probed using photo-induced dissociation (PID) action spectroscopy. The main photo-products are lumichrome and formylmethylflavin. Evidence is presented that the dissociation pathway leading to these products is non-statistical i.e. occurs during the excited state lifetime. This suggests that the stacking of the adenine and alloxazine chromophores, which enables ultra-fast quenching of the flavin excited state by photo-induced electron transfer in aqueous solution, is inhibited in vacuo. These results provide firm experimental confirmation that lumichrome formation from flavins proceeds via photo-induced, intra-molecular proton-coupled electron transfer.
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Affiliation(s)
- Mark H Stockett
- Stockholm University Department of Physics, Stockholm, Sweden.
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17
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Wellman SMJ, Jockusch RA. Tuning the Intrinsic Photophysical Properties of Chlorophylla. Chemistry 2017; 23:7728-7736. [DOI: 10.1002/chem.201605167] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Sydney M. J. Wellman
- Department of Chemistry; University of Toronto; 80 St. George Street Toronto Ontario M5S 3H6 Canada
| | - Rebecca A. Jockusch
- Department of Chemistry; University of Toronto; 80 St. George Street Toronto Ontario M5S 3H6 Canada
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18
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Kjær C, Stockett MH, Pedersen BM, Nielsen SB. Strong Impact of an Axial Ligand on the Absorption by Chlorophyll a and b Pigments Determined by Gas-Phase Ion Spectroscopy Experiments. J Phys Chem B 2016; 120:12105-12110. [PMID: 27933942 DOI: 10.1021/acs.jpcb.6b10547] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The microenvironments in photosynthetic proteins affect the absorption by chlorophyll (Chl) pigments. It is, however, a challenge to disentangle the impact on the transition energies of different perturbations, for example, the global electrostatics of the protein (nonbonded environmental effects), exciton coupling between Chl's, conformational variations, and binding of an axial ligand to the magnesium center. This is needed to distinguish between the two most commonly proposed mechanisms for energy transport in photosynthetic proteins, relying on either weakly or strongly coupled pigments. Here, on the basis of photodissociation action spectroscopy, we establish that the redshift of the Soret absorption band due to binding of a negatively charged carboxylate (as present in aspartic acid and glutamic acid residues) is 0.1-0.2 eV for Chl a and b. This effect is almost enough to reproduce the well-known green color of plants and can account for the strong spectral variation between Chl's. The experimental data serve to benchmark future high-level calculations of excited-state energies. Finally, we demonstrate that complexes between Chl a and histidine, tagged by a quaternary ammonium ion, can be made in the gas phase by electrospray ionization, but more work is needed to produce enough ions for gas-phase spectroscopy.
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Affiliation(s)
- Christina Kjær
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus, Denmark
| | - Mark H Stockett
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus, Denmark
| | - Bjarke M Pedersen
- Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus, Denmark
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