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Yoon H, Park S, Lim M. Photodissociation Dynamics of Nitric Oxide from N-Acetylcysteine- or N-Acetylpenicillamine-bound Roussin's Red Ester. ACS OMEGA 2021; 6:27158-27169. [PMID: 34693136 PMCID: PMC8529681 DOI: 10.1021/acsomega.1c03820] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/29/2021] [Indexed: 05/05/2023]
Abstract
The photochemical release of nitric oxide (NO) from a NO precursor is advantageous in terms of spatial, temporal, and dosage control of NO delivery to target sites. To realize full control of the quantitative NO administration from photoactivated NO precursors, it is necessary to have detailed dynamical information on the photodissociation of NO from NO precursors. We synthesized two new water-soluble Roussin's red esters (RREs), [Fe2(μ-N-acetylcysteine)2(NO)4] and [Fe2(μ-N-acetylpenicillamine)2(NO)4], which have five times longer lifetime than the well-known [Fe2(μ-cysteine)2(NO)4]. The photodissociation dynamics of NO from these RREs in water were investigated over a broad time range from 0.3 ps to 10 μs after excitation at 310 and 400 nm using femtosecond time-resolved infrared (IR) spectroscopy. When these RREs are excited, they either release one NO, producing a radical species deficient in one NO (R), [Fe2(μ-RS)2(NO)3], or relax into the ground state without photodeligation via an electronically excited intermediate state (M). R appears immediately after photoexcitation, suggesting that one NO is photodissociated faster than 0.3 ps. A certain fraction of R undergoes geminate recombination (GR) with NO with a time constant of 7-9 ps, while the remaining R competitively binds to the solvent. Solvent-bound R eventually bimolecularly recombines with NO with a rate constant of (1.3-1.6) × 108 M-1 s-1. For a given RRE molecule, the fractional yield of M (0.62-0.76) depends on the excitation wavelength (λex); however, the relaxation time of M (6 ± 1 ns) is independent of λex. Although the primary quantum yield of NO photodissociation (Φ1) was found to be 0.24-0.38, the final yield of NO suitable for other reactions (Φ2) was reduced to 0.14-0.29 due to the picosecond GR of the dissociated NO with R. Detailed photoexcitation dynamics of RRE can be utilized in the quantitative control of NO administration at a specific site and time, promoting pin-point usage of NO in chemistry and biology. We demonstrate that femtosecond IR spectroscopy combined with quantum chemical calculations is a powerful method for obtaining detailed dynamic information on photoactivated NO precursors such as Φ1 and Φ2, the GR yield, and secondary reactions of the nascent photoproducts, which are essential information for the design of efficient photoactivated NO precursors and their quantitative utilization.
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Unruh T, Domenianni LI, Vöhringer P. Photo-induced primary processes of trans-[Co(acac) 2(N 3)(py)] in liquid solution studied by femtosecond vibrational and electronic spectroscopies. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1964043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Tobias Unruh
- Abteilung für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
| | - Luis I. Domenianni
- Abteilung für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
| | - Peter Vöhringer
- Abteilung für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
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Straub S, Vöhringer P. Ultrafast "end-on"-to-"side-on" binding-mode isomerization of an iron-carbon dioxide complex. Phys Chem Chem Phys 2021; 23:17826-17835. [PMID: 34397055 DOI: 10.1039/d1cp02300d] [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
Carbon dioxide (CO2) binding by transition metals is a captivating phenomenon with a tremendous impact in environmental science and technology, most notably, for establishing circular economies based on greenhouse gas emissions. The molecular and electronic structures of coordination compounds containing CO2 can be studied in great detail using photochemical precursors bearing the photolabile oxalato-ligand. Here, we study the photoinduced elementary dynamics of the ferric complex, [FeIII(cyclam)(C2O4)]+, in dimethyl sulfoxide solution using femtosecond mid-infrared spectroscopy following oxalate-to-iron charge transfer excitation with 266 nm pulses. The pump-probe response in the ν3-region of carbon dioxide gives unequivocal evidence that a CO2-molecule is detached from the metal within only 500 fs and with a primary quantum yield of 38%. Simultaneously, a primary ferrous product is formed that carries a carbon dioxide radical anion ligand absorbing at 1649 cm-1, which is linked to the metal in a bent-O-"end-on" fashion. This primary ηO,bent1-product is formed with substantial excess vibrational energy, which relaxes on a time scale of several picoseconds. Prior to full thermalization, however, a fraction of the ferrous primary product can structurally isomerize at a rate of 1/(3.5 ps) to a secondary ηCO2-product absorbing at 1727 cm-1, which features a bent carbon dioxide ligand that is linked to the metal in a "side-on" fashion. The ηO,bent1-to-ηCO2 isomerization requires an intersystem crossing from the sextet to the quartet state, which rationalizes a partial trapping of the system in the metastable bent-O-"end-on" geometry. Finally, a fraction (62%) of the initially photoexcited complexes can return without structural changes to the parent's electronic ground state, but dressed with excess kinetic energy, which relaxes again on a time scale of several picoseconds.
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Affiliation(s)
- Steffen Straub
- Lehrstuhl für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie Rheinische Friedrich-Wilhelms, Universität Wegelerstraße 12, 53115 Bonn, Germany.
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Schluschaß B, Borter JH, Rupp S, Demeshko S, Herwig C, Limberg C, Maciulis NA, Schneider J, Würtele C, Krewald V, Schwarzer D, Schneider S. Cyanate Formation via Photolytic Splitting of Dinitrogen. JACS AU 2021; 1:879-894. [PMID: 34240082 PMCID: PMC8243327 DOI: 10.1021/jacsau.1c00117] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Indexed: 05/05/2023]
Abstract
Light-driven N2 cleavage into molecular nitrides is an attractive strategy for synthetic nitrogen fixation. However, suitable platforms are rare. Furthermore, the development of catalytic protocols via this elementary step suffers from poor understanding of N-N photosplitting within dinitrogen complexes, as well as of the thermochemical and kinetic framework for coupled follow-up chemistry. We here present a tungsten pincer platform, which undergoes fully reversible, thermal N2 splitting and reverse nitride coupling, allowing for experimental derivation of thermodynamic and kinetic parameters of the N-N cleavage step. Selective N-N splitting was also obtained photolytically. DFT computations allocate the productive excitations within the {WNNW} core. Transient absorption spectroscopy shows ultrafast repopulation of the electronic ground state. Comparison with ground-state kinetics and resonance Raman data support a pathway for N-N photosplitting via a nonstatistically vibrationally excited ground state that benefits from vibronically coupled structural distortion of the core. Nitride carbonylation and release are demonstrated within a full synthetic cycle for trimethylsilylcyanate formation directly from N2 and CO.
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Affiliation(s)
- Bastian Schluschaß
- University
of Göttingen, Institute for Inorganic
Chemistry, Tammannstraße
4, 37077 Göttingen, Germany
| | - Jan-Hendrik Borter
- Department
of Dynamics at Surfaces, Max Planck Institute
for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Severine Rupp
- Theoretische
Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 4, 64287 Darmstadt, Germany
| | - Serhiy Demeshko
- University
of Göttingen, Institute for Inorganic
Chemistry, Tammannstraße
4, 37077 Göttingen, Germany
| | - Christian Herwig
- Institut
für Chemie, Humboldt Universität
zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Christian Limberg
- Institut
für Chemie, Humboldt Universität
zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Nicholas A. Maciulis
- Department
of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405-7102, United States
| | - Jessica Schneider
- University
of Göttingen, Institute for Inorganic
Chemistry, Tammannstraße
4, 37077 Göttingen, Germany
| | - Christian Würtele
- University
of Göttingen, Institute for Inorganic
Chemistry, Tammannstraße
4, 37077 Göttingen, Germany
| | - Vera Krewald
- Theoretische
Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 4, 64287 Darmstadt, Germany
| | - Dirk Schwarzer
- Department
of Dynamics at Surfaces, Max Planck Institute
for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Sven Schneider
- University
of Göttingen, Institute for Inorganic
Chemistry, Tammannstraße
4, 37077 Göttingen, Germany
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