ORCID Profile
0000-0002-3798-5128
Current Organisations
E O Lawrence Berkeley National Laboratory
,
CSIRO
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Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3SC00911D
Abstract: The gas-phase preparation of naphthalene (C 10 H 8 ) molecule has been revealed through an isomer selective product detection via the reaction of the resonantly stabilized benzyl and the propargyl radicals.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CP02042G
Abstract: 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.
Publisher: American Chemical Society (ACS)
Date: 04-05-2022
DOI: 10.1021/ACS.LANGMUIR.2C00279
Abstract: A mechanistic study is reported for the reactions of singlet oxygen (
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CP01350C
Abstract: Protonated and deprotonated 9-methylguanine follow completely different oxidation routes.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CP02216K
Abstract: 1 H -Phenalene can be synthesized via the reaction of the 1-naphthyl radical with methylacetylene and allene under high temperature conditions prevalent in carbon-rich circumstellar environments and combustion systems.
Publisher: American Chemical Society (ACS)
Date: 26-01-2023
DOI: 10.1021/JACS.2C12045
Publisher: Springer Science and Business Media LLC
Date: 15-08-2019
DOI: 10.1038/S41467-019-11652-5
Abstract: Polycyclic aromatic hydrocarbons (PAHs) represent key molecular building blocks leading to carbonaceous nanoparticles identified in combustion systems and extraterrestrial environments. However, the understanding of their formation and growth in these high temperature environments has remained elusive. We present a mechanism through laboratory experiments and computations revealing how the prototype PAH—naphthalene—can be efficiently formed via a rapid 1-indenyl radical—methyl radical reaction. This versatile route converts five- to six-membered rings and provides a detailed view of high temperature mass growth processes that can eventually lead to graphene-type PAHs and two-dimensional nanostructures providing a radical new view about the transformations of carbon in our universe.
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CP53736F
Abstract: We present a study on the reactions of singlet oxygen O2[a(1)Δg] with hydrated protonated and deprotonated cysteine (Cys) in the gas phase, including measurements of the effects of collision energy (E(col)) and hydration number on reaction cross sections over a center-of-mass E(col) range from 0.05 to 1.0 eV. The aim is to probe how successive addition of water molecules changes the oxidation chemistry of Cys in the gas phase. Hydrated clusters, generated by electrospray ionization, have structures of HSCH2CH(NH3(+))CO2H(H2O)(1,2) and HSCH2CH(NH2)CO2(-)(H2O)(1,2) for protonated and deprotonated forms, respectively. In contrast to (1)O2 reactions with dehydrated protonated/deprotonated Cys of which hydroperoxide products all decomposed, reactions with hydrated protonated/deprotonated Cys yielded stable hydroperoxide products, analogous to photooxidation reaction of Cys in solution. We investigated the number of water ligands necessary to produce a stable hydroperoxide, and found that a single water molecule suffices--that is, to relax nascent, energized hydroperoxide in the hydrated cluster by elimination of water. Hydrated protonated Cys shows higher reaction efficiency than the hydrated deprotonated one, particularly with the addition of the second water ligand. Reactions of hydrated protonated/deprotonated Cys are suppressed by E(col), becoming negligible at E(col) ≥ 0.5 eV. Density functional theory calculations were used to locate reaction coordinates for these systems. Quasi-classical, direct dynamics trajectory simulations were performed for HSCH2CH(NH3(+))CO2H(H2O) + (1)O2 at the B3LYP/4-31G(d) level of theory. Analysis of trajectories highlights the importance of complex mediation in the early stages of the reaction, and illustrates that water can catalyze proton transfer within the hydrated complex.
Publisher: American Chemical Society (ACS)
Date: 04-06-2021
Publisher: American Chemical Society (ACS)
Date: 13-11-2019
Abstract: We report a kinetics and mechanistic study on the
Publisher: American Chemical Society (ACS)
Date: 07-03-2022
Abstract: Polyol-water clusters provide a template to probe ionization and solvation processes of paramount interest in atmospheric and interstellar chemistry. We generate glycerol water clusters in a continuous supersonic jet expansion and interrogate the neutral species with synchrotron-based tunable vacuum ultraviolet photoionization mass spectrometry. A series of glycerol fragments (
Publisher: American Association for the Advancement of Science (AAAS)
Date: 21-05-2021
Abstract: The propargyl self-reaction leading to C 6 H 6 isomers is critical in our understanding of the evolution of carbon in our galaxy.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0CP06537D
Abstract: Corannulene can be formed through molecular mass growth processes in circumstellar envelopes.
Publisher: Wiley
Date: 11-05-2020
Publisher: Wiley
Date: 27-01-2016
Abstract: The chemistry of singlet O2 toward the guanine base of DNA is highly relevant to DNA lesion, mutation, cell death, and pathological conditions. This oxidative damage is initiated by the formation of a transient endoperoxide through the Diels-Alder cycloaddition of singlet O2 to the guanine imidazole ring. However, no endoperoxide formation was directly detected in native guanine or guanosine, even at -100 °C. Herein, gas-phase ion-molecule scattering mass spectrometry was utilized to capture unstable endoperoxides in the collisions of hydrated guanine ions (protonated or deprotonated) with singlet O2 at ambient temperature. Corroborated by results from potential energy surface exploration, kinetic modeling, and dynamics simulations, various aspects of endoperoxide formation and transformation (including its dependence on guanine ionization and hydration states, as well as on collision energy) were determined. This work has pieced together reaction mechanisms, kinetics, and dynamics data concerning the early stage of singlet O2 induced guanine oxidation, which is missing from conventional condensed-phase studies.
Publisher: Elsevier BV
Date: 08-2022
Publisher: American Chemical Society (ACS)
Date: 28-03-2014
DOI: 10.1021/JP500780M
Abstract: It has been proposed (J. Phys. Chem. B 2011, 115, 2671) that the ammonium group is involved in the gas-phase reaction of protonated methionine (MetH(+)) with singlet oxygen (1)O2, yielding hydrogen peroxide and a dehydro compound of MetH(+) where the -NH3(+) transforms into cyclic -NH2-. For the work reported, the gas-phase reaction of protonated N-acetylmethionine (Ac-MetH(+)) with (1)O2 was examined, including the measurements of reaction products and cross sections over a center-of-mass collision energy (Ecol) range from 0.05 to 1.0 eV using a guided-ion-beam apparatus. The aim is to probe how the acetylation of the ammonium group affects the oxidation chemistry of the ensuing Ac-MetH(+). Properties of intermediates, transition states, and products along the reaction coordinate were explored using density functional theory calculations and Rice-Ramsperger-Kassel-Marcus (RRKM) modeling. Direct dynamics trajectory simulations were carried out at Ecol of 0.05 and 0.1 eV using the B3LYP/4-31G(d) level of theory. In contrast to the highly efficient reaction of MetH(+) + (1)O2, the reaction of Ac-MetH(+) + (1)O2 is extremely inefficient, despite there being exoergic pathways. Two product channels were observed, corresponding to transfer of two H atoms from Ac-MetH(+) to (1)O2 (H2T), and methyl elimination (ME) from a sulfone intermediate complex. Both channels are inhibited by collision energies, becoming negligible at Ecol > 0.2 eV. Analysis of RRKM and trajectory results suggests that a complex-mediated mechanism might be involved at very low Ecol, but direct, nonreactive collisions prevail over the entire Ecol range and physical quenching of (1)O2 occurs during the early stage of collisions.
Publisher: Springer Science and Business Media LLC
Date: 03-04-2019
DOI: 10.1038/S41467-019-09224-8
Abstract: A synthetic route to racemic helicenes via a vinylacetylene mediated gas phase chemistry involving elementary reactions with aryl radicals is presented. In contrast to traditional synthetic routes involving solution chemistry and ionic reaction intermediates, the gas phase synthesis involves a targeted ring annulation involving free radical intermediates. Exploiting the simplest helicene as a benchmark, we show that the gas phase reaction of the 4-phenanthrenyl radical ([C 14 H 9 ] • ) with vinylacetylene (C 4 H 4 ) yields [4]-helicene (C 18 H 12 ) along with atomic hydrogen via a low-barrier mechanism through a resonance-stabilized free radical intermediate (C 18 H 13 ). This pathway may represent a versatile mechanism to build up even more complex polycyclic aromatic hydrocarbons such as [5]- and [6]-helicene via stepwise ring annulation through bimolecular gas phase reactions in circumstellar envelopes of carbon-rich stars, whereas secondary reactions involving hydrogen atom assisted isomerization of thermodynamically less stable isomers of [4]-helicene might be important in combustion flames as well.
Publisher: Wiley
Date: 09-01-2023
Abstract: The simplest polycyclic aromatic hydrocarbon (PAH) carrying a five‐membered ring—9 H ‐fluorene (C 13 H 10 )—is produced isomer‐specifically in the gas phase by reacting benzyl (C 7 H 7 ⋅) with phenyl (C 6 H 5 ⋅) radicals in a pyrolytic reactor coupled with single photon ionization mass spectrometry. The unconventional mechanism of reaction is supported by theoretical calculations, which first produces diphenylmethane and unexpected 1‐(6‐methylenecyclohexa‐2,4‐dienyl)benzene intermediates (C 13 H 12 ) accessed via addition of the phenyl radical to the ortho position of the benzyl radical. These findings offer convincing evidence for molecular mass growth processes defying conventional wisdom that radical‐radical reactions are initiated through recombination at their radical centers. The structure of 9 H ‐fluorene acts as a molecular building block for complex curved nanostructures like fullerenes and nanobowls providing fundamental insights into the hydrocarbon evolution in high temperature settings.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1CP02169A
Abstract: Quinoline and isoquinoline can be formed through molecular mass growth processes in low-temperature environments.
Publisher: Wiley
Date: 18-04-2019
Abstract: The reactions of the indenyl radicals with acetylene (C
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0CP03846F
Abstract: The reaction of indenyl radicals with vinylacetylene leads to cyclopentanaphthalene at low temperature.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CP04375K
Abstract: Nucleation and crystallization arising from liquid to solid phase are involved in a multitude of processes in fields ranging from materials science to biology. Controlling the thermodynamics and kinetics of growth is advantageous to help tune the formation of complex morphologies. Here, we harness wide-angle X-ray scattering and vibrational spectroscopy to elucidate the mechanism for crystallization and growth of the metal-organic framework Co-MOF-74 within microscopic volumes enclosed in a capillary and an attenuated total reflection microchip reactor. The experiments reveal molecular and structural details of the growth processes, while the results of plane wave density functional calculations allow identification of lattice and linker modes in the formed crystals. Synthesis of the metal-organic framework with microscopic volumes leads to monodisperse and micron-sized crystals, in contrast to those typically observed under bulk reaction conditions. Reduction in the volume of reagents within the microchip reactor was found to accelerate the reaction rate. The coupling of spectroscopy with scattering to probe reactions in microscopic volumes promises to be a useful tool in the synthetic chemist's kit to understand chemical bonding and has potential in designing complex materials.
Publisher: American Chemical Society (ACS)
Date: 26-08-2015
DOI: 10.1007/S13361-015-1237-4
Abstract: We report a reaction apparatus developed to monitor singlet oxygen ((1)O2) reactions in solution using on-line ESI mass spectrometry and spectroscopy measurements. (1)O2 was generated in the gas phase by the reaction of H2O2 with Cl2, detected by its emission at 1270 nm, and bubbled into aqueous solution continuously. (1)O2 concentrations in solution were linearly related to the emission intensities of airborne (1)O2, and their absolute scales were established based on a calibration using 9,10-anthracene dipropionate dianion as an (1)O2 trapping agent. Products from (1)O2 oxidation were monitored by UV-Vis absorption and positive/negative ESI mass spectra, and product structures were elucidated using collision-induced dissociation-tandem mass spectrometry. To suppress electrical discharge in negative ESI of aqueous solution, methanol was added to electrospray via in-spray solution mixing using theta-glass ESI emitters. Capitalizing on this apparatus, the reaction of (1)O2 with methionine was investigated. We have identified methionine oxidation intermediates and products at different pH, and measured reaction rate constants. (1)O2 oxidation of methionine is mediated by persulfoxide in both acidic and basic solutions. Persulfoxide continues to react with another methionine, yielding methionine sulfoxide as end-product albeit with a much lower reaction rate in basic solution. Density functional theory was used to explore reaction potential energy surfaces and establish kinetic models, with solvation effects simulated using the polarized continuum model. Combined with our previous study of gas-phase methionine ions with (1)O2, evolution of methionine oxidation pathways at different ionization states and in different media is described.
Publisher: American Chemical Society (ACS)
Date: 27-10-2020
Publisher: American Chemical Society (ACS)
Date: 30-12-2022
DOI: 10.1021/ACS.JPCLETT.1C03733
Abstract: Resonantly stabilized free radicals (RSFRs) have been contemplated as fundamental molecular building blocks and reactive intermediates in molecular mass growth processes leading to polycyclic aromatic hydrocarbons (PAHs) and carbonaceous nanoparticles on Earth and in deep space. By combining molecular beams and computational fluid dynamics simulations, we provide compelling evidence on the formation of benzene via the cyclopentadienyl-methyl reaction and of naphthalene through the cyclopentadienyl self-reaction, respectively. These systems offer benchmarks for the conversion of a five-membered ring to the 6π-aromatic (benzene) and the generation of the simplest 10π-PAH (naphthalene) at elevated temperatures. These results uncover molecular mass growth processes from the "bottom up" via RSFRs in high temperature circumstellar environments and combustion systems expanding our fundamental knowledge of the organic, hydrocarbon chemistry in our universe.
Publisher: Wiley
Date: 13-02-2019
Abstract: For the last decades, the hydrogen-abstraction-acetylene-addition (HACA) mechanism has been widely invoked to rationalize the high-temperature synthesis of PAHs as detected in carbonaceous meteorites (CM) and proposed to exist in the interstellar medium (ISM). By unravelling the chemistry of the 9-phenanthrenyl radical ([C
Publisher: American Chemical Society (ACS)
Date: 13-07-2023
Publisher: Springer Science and Business Media LLC
Date: 10-02-2022
DOI: 10.1038/S41467-022-28466-7
Abstract: Polycyclic aromatic hydrocarbons (PAHs) are prevalent in deep space and on Earth as products in combustion processes bearing direct relevance to energy efficiency and environmental remediation. Reactions between hydrocarbon radicals in particular have been invoked as critical molecular mass growth processes toward cyclization leading to these PAHs. However, the mechanism of the formation of PAHs through radical – radical reactions are largely elusive. Here, we report on a combined computational and experimental study of the benzyl (C 7 H 7 ) radical self-reaction to phenanthrene and anthracene (C 14 H 10 ) through unconventional, isomer-selective excited state dynamics. Whereas phenanthrene formation is initiated via a barrierless recombination of two benzyl radicals on the singlet ground state surface, formation of anthracene commences through an exotic transition state on the excited state triplet surface through cycloaddition. Our findings challenge conventional wisdom that PAH formation via radical-radical reactions solely operates on electronic ground state surfaces and open up a previously overlooked avenue for a more “rapid” synthesis of aromatic, multi-ringed structures via excited state dynamics in the gas phase.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CP06670D
Abstract: The intra-base-pair proton transfer and non-RRKM unimolecular kinetics of deprotonated guanine·cytosine base pairs.
Publisher: Wiley
Date: 09-08-2018
Abstract: We report an experimental and computational study on the
Publisher: Wiley
Date: 11-05-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4CP03550J
Abstract: Oxidation of histidine by 1 O 2 is an important process associated with oxidative damage to proteins during aging, diseases and photodynamic therapy of tumors and jaundice, and photochemical transformations of biological species in the troposphere.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CP03084E
Abstract: Racemic mixtures of [5] and [6]helicenes can form in the gas-phase of the interstellar medium at ultralow temperatures in the absence of reaction barriers via molecular mass growth processes.
Publisher: American Chemical Society (ACS)
Date: 25-01-2017
Abstract: 8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) is one of the most common DNA lesions resulting from reactive oxygen species and ionizing radiation, and is involved in mutagenesis, carcinogenesis, and cell death. Notably, 8-oxodGuo is more reactive toward singlet (a
Publisher: American Chemical Society (ACS)
Date: 11-08-2017
Abstract: The reactivity of cystine toward electronically excited singlet O
Publisher: American Chemical Society (ACS)
Date: 19-12-2017
Abstract: We report a kinetic and mechanistic study on the title reactions, in which
Publisher: American Chemical Society (ACS)
Date: 09-10-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CP02930C
Abstract: The three-ring polycyclic aromatic hydrocarbons (PAHs) 3H-benz[e]indene (C
Publisher: American Association for the Advancement of Science (AAAS)
Date: 08-09-2023
Location: United States of America
No related grants have been discovered for Wenchao Lu.