scholarly journals Functionalized Hydroperoxide Formation from the Reaction of Methacrolein-Oxide, an Isoprene-Derived Criegee Intermediate, with Formic Acid: Experiment and Theory

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 3058
Author(s):  
Michael F. Vansco ◽  
Kristen Zuraski ◽  
Frank A. F. Winiberg ◽  
Kendrew Au ◽  
Nisalak Trongsiriwat ◽  
...  
Keyword(s):  
Formic Acid ◽  
Appearance Energy ◽  
Electronic Structure Calculations ◽  
Methyl Vinyl ◽  
Photoionization Mass Spectrometry ◽  
Hydroperoxide Formation ◽  
Reaction Proceeds ◽  
Theoretical Predictions ◽  
Structure Calculations ◽  
Rapid Appearance

Methacrolein oxide (MACR-oxide) is a four-carbon, resonance-stabilized Criegee intermediate produced from isoprene ozonolysis, yet its reactivity is not well understood. This study identifies the functionalized hydroperoxide species, 1‑hydroperoxy-2-methylallyl formate (HPMAF), generated from the reaction of MACR-oxide with formic acid using multiplexed photoionization mass spectrometry (MPIMS, 298 K = 25 °C, 10 torr = 13.3 hPa). Electronic structure calculations indicate the reaction proceeds via an energetically favorable 1,4-addition mechanism. The formation of HPMAF is observed by the rapid appearance of a fragment ion at m/z 99, consistent with the proposed mechanism and characteristic loss of HO2 upon photoionization of functional hydroperoxides. The identification of HPMAF is confirmed by comparison of the appearance energy of the fragment ion with theoretical predictions of its photoionization threshold. The results are compared to analogous studies on the reaction of formic acid with methyl vinyl ketone oxide (MVK-oxide), the other four-carbon Criegee intermediate in isoprene ozonolysis.

Mechanistic insights into the light-driven hydrogen evolution reaction from formic acid mediated by an iridium photocatalyst

2017 ◽  
Vol 7 (13) ◽  
pp. 2763-2771 ◽  
Author(s):  
Pin Xiao ◽  
Dan Wu ◽  
Wei-Hai Fang ◽  
Ganglong Cui
Keyword(s):  
Electronic Structure ◽  
Formic Acid ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electronic Structure Calculations ◽  
Structure Calculations

Electronic structure calculations shed important mechanistic light on light-driven hydrogen evolution from formic acid mediated by an iridium photocatalyst.

scholarly journals Probing solvation and reactivity in ionized polycyclic aromatic hydrocarbon–water clusters with photoionization mass spectrometry and electronic structure calculations

2019 ◽  
Vol 217 ◽  
pp. 414-433 ◽  
Author(s):  
Bo Xu ◽  
Tamar Stein ◽  
Utuq Ablikim ◽  
Ling Jiang ◽  
Josie Hendrix ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Polycyclic Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbon ◽  
Water Clusters ◽  
Theoretical Calculations ◽  
Electronic Structure Calculations ◽  
Photoionization Mass Spectrometry ◽  
Polycyclic Aromatic ◽  
Structure Calculations ◽  
Insight Into

Synchrotron based mass spectrometry coupled with theoretical calculations provides insight into polycyclic aromatic hydrocarbon water interactions.

Identification of C5HxIsomers in Fuel-Rich Flames by Photoionization Mass Spectrometry and Electronic Structure Calculations

2006 ◽  
Vol 110 (13) ◽  
pp. 4376-4388 ◽  
Author(s):  
Nils Hansen ◽  
Stephen J. Klippenstein ◽  
James A. Miller ◽  
Juan Wang ◽  
Terrill A. Cool ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Electronic Structure ◽  
Electronic Structure Calculations ◽  
Photoionization Mass Spectrometry ◽  
Structure Calculations

scholarly journals Exciton energy transfer reveals spectral signatures of excited states in clusters

2020 ◽  
Vol 22 (25) ◽  
pp. 14284-14292
Author(s):  
Wenchao Lu ◽  
Ricardo B. Metz ◽  
Tyler P. Troy ◽  
Oleg Kostko ◽  
Musahid Ahmed
Keyword(s):  
Mass Spectrometry ◽  
Energy Transfer ◽  
Excited States ◽  
Electronic Excitation ◽  
Electronic Structure Calculations ◽  
Exciton Energy ◽  
Penning Ionization ◽  
Spectral Signatures ◽  
Photoionization Mass Spectrometry ◽  
Structure Calculations

Electronic excitation and concomitant energy transfer leading to Penning ionization in argon–acetylene clusters are investigated with synchrotron-based photoionization mass spectrometry and electronic structure calculations.

scholarly journals Direct kinetic measurements and theoretical predictions of an isoprene-derived Criegee intermediate

2020 ◽  
Vol 117 (18) ◽  
pp. 9733-9740 ◽  
Author(s):  
Rebecca L. Caravan ◽  
Michael F. Vansco ◽  
Kendrew Au ◽  
M. Anwar H. Khan ◽  
Yu-Lin Li ◽  
...  
Keyword(s):  
Formic Acid ◽  
Transport Model ◽  
Thermal Conditions ◽  
Chem Phys ◽  
Kinetic Measurements ◽  
Atmospheric Species ◽  
Photoionization Mass Spectrometry ◽  
Criegee Intermediates ◽  
Atmospheric Processing ◽  
Theoretical Predictions

Isoprene has the highest emission into Earth’s atmosphere of any nonmethane hydrocarbon. Atmospheric processing of alkenes, including isoprene, via ozonolysis leads to the formation of zwitterionic reactive intermediates, known as Criegee intermediates (CIs). Direct studies have revealed that reactions involving simple CIs can significantly impact the tropospheric oxidizing capacity, enhance particulate formation, and degrade local air quality. Methyl vinyl ketone oxide (MVK-oxide) is a four-carbon, asymmetric, resonance-stabilized CI, produced with 21 to 23% yield from isoprene ozonolysis, yet its reactivity has not been directly studied. We present direct kinetic measurements of MVK-oxide reactions with key atmospheric species using absorption spectroscopy. Direct UV-Vis absorption spectra from two independent flow cell experiments overlap with the molecular beam UV-Vis-depletion spectra reported recently [M. F. Vansco, B. Marchetti, M. I. Lester, J. Chem. Phys. 149, 44309 (2018)] but suggest different conformer distributions under jet-cooled and thermal conditions. Comparison of the experimental lifetime herein with theory indicates only the syn-conformers are observed; anti-conformers are calculated to be removed much more rapidly via unimolecular decay. We observe experimentally and predict theoretically fast reaction of syn-MVK-oxide with SO2 and formic acid, similar to smaller alkyl-substituted CIs, and by contrast, slow removal in the presence of water. We determine products through complementary multiplexed photoionization mass spectrometry, observing SO3 and identifying organic hydroperoxide formation from reaction with SO2 and formic acid, respectively. The tropospheric implications of these reactions are evaluated using a global chemistry and transport model.

scholarly journals Theoretical predictions suggest carbon dioxide phases III and VII are identical

2017 ◽  
Vol 8 (11) ◽  
pp. 7374-7382 ◽  
Author(s):  
Watit Sontising ◽  
Yonaton N. Heit ◽  
Jessica L. McKinley ◽  
Gregory J. O. Beran
Keyword(s):  
Carbon Dioxide ◽  
Phase Diagram ◽  
High Pressure ◽  
Electronic Structure ◽  
Raman Spectra ◽  
Electronic Structure Calculations ◽  
Theoretical Predictions ◽  
Structure Calculations

Accurate electronic structure calculations for the structures and simulated Raman spectra of high-pressure carbon dioxide suggest phases III and VII are identical, and the phase diagram should be revised.

Message Passing Neural Networks for Partial Charge Assignment to Metal-Organic Frameworks

2020 ◽  
Author(s):  
Ali Raza ◽  
Arni Sturluson ◽  
Cory Simon ◽  
Xiaoli Fern
Keyword(s):  
Electronic Structure ◽  
Message Passing ◽  
Gas Adsorption ◽  
Metal Organic Frameworks ◽  
Computational Cost ◽  
Electronic Structure Calculations ◽  
High Fidelity ◽  
Partial Charges ◽  
Metal Organic ◽  
Structure Calculations

Virtual screenings can accelerate and reduce the cost of discovering metal-organic frameworks (MOFs) for their applications in gas storage, separation, and sensing. In molecular simulations of gas adsorption/diffusion in MOFs, the adsorbate-MOF electrostatic interaction is typically modeled by placing partial point charges on the atoms of the MOF. For the virtual screening of large libraries of MOFs, it is critical to develop computationally inexpensive methods to assign atomic partial charges to MOFs that accurately reproduce the electrostatic potential in their pores. Herein, we design and train a message passing neural network (MPNN) to predict the atomic partial charges on MOFs under a charge neutral constraint. A set of ca. 2,250 MOFs labeled with high-fidelity partial charges, derived from periodic electronic structure calculations, serves as training examples. In an end-to-end manner, from charge-labeled crystal graphs representing MOFs, our MPNN machine-learns features of the local bonding environments of the atoms and learns to predict partial atomic charges from these features. Our trained MPNN assigns high-fidelity partial point charges to MOFs with orders of magnitude lower computational cost than electronic structure calculations. To enhance the accuracy of virtual screenings of large libraries of MOFs for their adsorption-based applications, we make our trained MPNN model and MPNN-charge-assigned computation-ready, experimental MOF structures publicly available.<br>

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