1
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Saak CM, Backus EHG. The Role of Sum-Frequency Generation Spectroscopy in Understanding On-Surface Reactions and Dynamics in Atmospheric Model-Systems. J Phys Chem Lett 2024; 15:4546-4559. [PMID: 38636165 PMCID: PMC11071071 DOI: 10.1021/acs.jpclett.4c00392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 04/09/2024] [Accepted: 04/10/2024] [Indexed: 04/20/2024]
Abstract
Surfaces, both water/air and solid/water, play an important role in mediating a multitude of processes central to atmospheric chemistry, particularly in the aerosol phase. However, the study of both static and dynamic properties of surfaces is highly challenging from an experimental standpoint, leading to a lack of molecular level information about the processes that take place at these systems and how they differ from bulk. One of the few techniques that has been able to capture ultrafast surface phenomena is time-resolved sum-frequency generation (SFG) spectroscopy. Since it is both surface-specific and chemically sensitive, the extension of this spectroscopic technique to the time domain makes it possible to study dynamic processes on the femtosecond time scale. In this Perspective, we will explore recent advances made in the field both in terms of studying energy dissipation as well as chemical reactions and the role the surface geometry plays in these processes.
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Affiliation(s)
- Clara-Magdalena Saak
- University of Vienna, Faculty of Chemistry, Institute of Physical Chemistry, Währingerstrasse 42, 1090 Vienna, Austria
| | - Ellen H. G. Backus
- University of Vienna, Faculty of Chemistry, Institute of Physical Chemistry, Währingerstrasse 42, 1090 Vienna, Austria
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2
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Gaur A, Balasubramanian S. Liquid-Vapor Interface of Aqueous Ethylene Glycol Solutions: A Molecular Dynamics Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:230-240. [PMID: 38150706 DOI: 10.1021/acs.langmuir.3c02431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
While the organic constituent in an aqueous binary solution enriches its liquid-vapor (l-v) interface, the extent of enrichment can depend nonlinearly on its mole fraction. A microscopic quantification and rationalization of this behavior are crucial to understand the dependence of properties such as surface tension and evaporation rate of the solution on its composition. Extensive all-atom molecular dynamics simulations of aqueous ethylene glycol (EG) solutions show that the composition of the solution at the l-v interface deviates the most from that in the bulk solution at an EG mole fraction of 0.3. The population of EG molecules with their central C-C dihedral in the gauche conformation was found to be higher at the l-v interface than that in the bulk solution to facilitate the orientation of its hydrophobic methyl groups toward the vapor phase. Free energy calculations reveal that in dilute EG solutions, an EG molecule is most stable at the l-v interface. The behavior of vapor pressure in aqueous EG solutions is ideal and follows Raoult's law, while in contrast, the aqueous solution of dimethyl sulfoxide does not. A rationale for the same is provided through the orientational distribution of interfacial water molecules in the respective solutions.
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Affiliation(s)
- Anjali Gaur
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | - Sundaram Balasubramanian
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
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3
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Neisser RW, Davis JP, Alfieri ME, Harkins H, Petit AS, Tabor DP, Kidwell NM. Photophysical Outcomes of Water-Solvated Heterocycles: Single-Conformation Ultraviolet and Infrared Spectroscopy of Microsolvated 2-Phenylpyrrole. J Phys Chem A 2023; 127:10540-10554. [PMID: 38085923 DOI: 10.1021/acs.jpca.3c04472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
The molecular chromophores within brown carbon (BrC) aerosols absorb solar radiation at visible and near-ultraviolet wavelengths. This contributes to the overall warming of the troposphere and the photochemical aging of aerosols. In this investigation, we combine a suite of experimental and theoretical methods to reveal the conformation-specific ultraviolet and infrared spectroscopy of 2-phenylpyrrole (2PhPy)─an extended π-conjugated pyrrole derivative and a model BrC chromophore─along with its water microsolvated molecular complexes (2PhPy:nH2O, n = 1-3). Using resonant two-photon ionization and double-resonance holeburning techniques alongside MP3 (ground state) and ADC(3) (excited state) torsional potential energy surfaces and discrete variable representation simulations, we characterized the ultraviolet spectra of 2PhPy and 2PhPy:1H2O. This analysis revealed evidence for Herzberg-Teller vibronic coupling along the CH wagging and NH stretching coordinates of the aromatic rings. Conformation-specific infrared spectroscopy revealed extended hydrogen-bonding networks of the 2PhPy:nH2O complexes. Upon stepwise addition of H2O solvation, the nearest H2O acceptor forms a strong, noncovalent interaction with the pyrrole NH donor, while the second and third H2O partners interface with the phenyl and pyrrole aromatic rings through growing van der Waals π/H atom stabilization. A local-mode Hamiltonian approach was employed for comparison with the experimental spectra, thus identifying the vibrational spectral signatures to specific 2PhPy:nH2O oscillators.
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Affiliation(s)
- Ruby W Neisser
- Department of Chemistry, The College of William & Mary, Williamsburg, Virginia 23187-8795, United States
| | - John P Davis
- Department of Chemistry, The College of William & Mary, Williamsburg, Virginia 23187-8795, United States
| | - Megan E Alfieri
- Department of Chemistry, The College of William & Mary, Williamsburg, Virginia 23187-8795, United States
| | - Hayden Harkins
- Department of Chemistry and Biochemistry, California State University─Fullerton, Fullerton, California 92834-6866, United States
| | - Andrew S Petit
- Department of Chemistry and Biochemistry, California State University─Fullerton, Fullerton, California 92834-6866, United States
| | - Daniel P Tabor
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Nathanael M Kidwell
- Department of Chemistry, The College of William & Mary, Williamsburg, Virginia 23187-8795, United States
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4
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Roterman I, Stapor K, Konieczny L. Ab initio protein structure prediction: the necessary presence of external force field as it is delivered by Hsp40 chaperone. BMC Bioinformatics 2023; 24:418. [PMID: 37932669 PMCID: PMC10629080 DOI: 10.1186/s12859-023-05545-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 10/27/2023] [Indexed: 11/08/2023] Open
Abstract
BACKGROUND The aqueous environment directs the protein folding process towards the generation of micelle-type structures, which results in the exposure of hydrophilic residues on the surface (polarity) and the concentration of hydrophobic residues in the center (hydrophobic core). Obtaining a structure without a hydrophobic core requires a different type of external force field than those generated by a water. The examples are membrane proteins, where the distribution of hydrophobicity is opposite to that of water-soluble proteins. Apart from these two extreme examples, the process of protein folding can be directed by chaperones, resulting in a structure devoid of a hydrophobic core. RESULTS The current work presents such example: DnaJ Hsp40 in complex with alkaline phosphatase PhoA-U (PDB ID-6PSI)-the client molecule. The availability of WT form of the folding protein-alkaline phosphatase (PDB ID-1EW8) enables a comparative analysis of the structures: at the stage of interaction with the chaperone and the final, folded structure of this biologically active protein. The fuzzy oil drop model in its modified FOD-M version was used in this analysis, taking into account the influence of an external force field, in this case coming from a chaperone. CONCLUSIONS The FOD-M model identifies the external force field introduced by chaperon influencing the folding proces. The identified specific external force field can be applied in Ab Initio protein structure prediction as the environmental conditioning the folding proces.
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Affiliation(s)
- Irena Roterman
- Department of Bioinformatics and Telemedicine, Jagiellonian University - Medical College, Medyczna 7, 30-688, Krakow, Poland.
| | - Katarzyna Stapor
- Department of Applied Informatics, Silesian University of Technology, Gliwice, Poland
| | - Leszek Konieczny
- Chair of Medical Biochemistry, Jagiellonian University - Medical College, Kopernika 7, 31-034, Krakow, Poland
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5
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Pei J, Zhao Y, Zhang S, Yu X, Tian Z, Sun Y, Ma S, Zhao RS, Meng J, Chen X, Chen F. A Surface Matrix of Au NPs Decorated Graphdiyne for Multifunctional Laser Desorption/Ionization Mass Spectrometry. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37909321 DOI: 10.1021/acsami.3c08962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
The development of the valid strategy to enhance laser desorption/ionization efficiency gives rise to widespread concern in surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) technology. Herein, a hybrid of Au NP-decorated graphdiyne (Au/GDY) was fabricated and employed as the SALDI-MS matrix for the first time, and a mechanism based on photothermal and photochemical energy conversions was proposed to understand LDI processes. Given theoretical simulations and microstructure characterizations, it was revealed that the formation of a coupled thermal field and internal electric field endow the as-prepared Au/GDY matrix with superior desorption and ionization efficiency, respectively. Moreover, laser-induced matrix ablation introduced strain and defect level into the Au/GDY hybrid, suppressing the recombination of charge carriers and thereby facilitating analyte ionization. The optimized Au/GDY matrix allowed for reliable detection of trace sulfacetamide and visualization of exogenous/endogenous components in biological tissues. This work offers an integrated solution to promote LDI efficiency based on collaborative photothermal conversion and internal electric field, and may inspire the design of novel semiconductor-based surface matrices.
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Affiliation(s)
- Jingxuan Pei
- Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China
| | - Yanfang Zhao
- Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China
- Shandong Analysis and Test Center, Key Laboratory for Applied Technology of Sophisticated Analytical Instruments of Shandong Province, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250014, China
| | - Shuting Zhang
- Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China
| | - Xiang Yu
- Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China
| | - Zhenfei Tian
- Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China
| | - Yibo Sun
- Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China
| | - Shiqing Ma
- Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China
| | - Ru-Song Zhao
- Shandong Analysis and Test Center, Key Laboratory for Applied Technology of Sophisticated Analytical Instruments of Shandong Province, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250014, China
| | - Jianping Meng
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 101400, China
| | - Xiangfeng Chen
- Shandong Analysis and Test Center, Key Laboratory for Applied Technology of Sophisticated Analytical Instruments of Shandong Province, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250014, China
| | - Fang Chen
- Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China
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6
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Carpenter AP, Golbek TW. "Nonlinear" pursuit of understanding pollutant accumulation and chemistry at environmental and biological interfaces. Biointerphases 2023; 18:058501. [PMID: 37728303 DOI: 10.1116/6.0003059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 08/25/2023] [Indexed: 09/21/2023] Open
Abstract
Over the past few decades, the public recognition of the prevalence of certain classes of pollutants, such as perfluoroalkyl substances and nanoplastics, within the environment, has sparked growing concerns over their potential impact on environmental and human health. Within both environmental and biological systems, the adsorption and structural organization of pollutants at aqueous interfaces can greatly impact the chemical reactivity and transformation. Experimentally probing chemical behavior at interfaces can often pose a problem due to bulk solvated molecules convoluting molecular signatures from interfacial molecules. To solve this problem, there exist interface-specific nonlinear spectroscopy techniques that can directly probe both macroscopic planar interfaces and nanoplastic interfaces in aqueous environments. These techniques can provide essential information such as chemical adsorption, structure, and reactivity at interfaces. In this perspective, these techniques are presented with obvious advantages for studying the chemical properties of pollutants adsorbed to environmental and biological interfaces.
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Affiliation(s)
- Andrew P Carpenter
- School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331
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7
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Karre AV, Valsaraj KT, Vasagar V. Review of air-water interface adsorption and reactions between trace gaseous organic and oxidant compounds. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 873:162367. [PMID: 36822420 DOI: 10.1016/j.scitotenv.2023.162367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/06/2023] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
The surface chemistry of the atmospheric aerosol through homogeneous and heterogeneous catalytic reactions in the bulk water and the air-water surface is reviewed. Water plays a critical role as a substrate or an actual reactant in atmospheric reactions. The atmospheric aerosol differs in shape and surface area. Many gaseous reactive species and oxidants react at the air-water surface. Different thermodynamic methods to estimate partitioning coefficients are explored. The Gibbs free energy is reduced when reactant gaseous species react with oxidant at the air-water surface; this phenomenon is explained using examples. Langmuir-Hinshelwood reaction mechanism to quantify the heterogeneous reaction rate at the air-water interface is discussed. Critical comparisons of various sampling techniques used to analyze adsorption and reaction at the water surface are presented. The heterogeneous reaction rate at the air-water surface is significantly higher than in the bulk water phase due to a cage effect, higher rate of reactions, and lower Gibbs free energy of adsorption.
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Affiliation(s)
| | - Kalliat T Valsaraj
- Cain Department of Chemical Engineering, Louisiana State University, LA 70803, United States
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8
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Martins-Costa MTC, Ruiz-López MF. Probing solvation electrostatics at the air–water interface. Theor Chem Acc 2023. [DOI: 10.1007/s00214-023-02969-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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9
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Schulte R, Löcker M, Ihmels H, Heide M, Engelhard C. Pushing Photochemistry into Water: Acceleration of the Di-π-Methane Rearrangement and the Paternó-Büchi Reaction "On-Water". Chemistry 2023; 29:e202203203. [PMID: 36398899 PMCID: PMC10107481 DOI: 10.1002/chem.202203203] [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: 10/13/2022] [Revised: 11/14/2022] [Accepted: 11/17/2022] [Indexed: 11/19/2022]
Abstract
Two representative organic photoreactions, namely a bimolecular photocycloaddition and a monomolecular photorearrangement, are presented that are accelerated when the reaction is performed "on-water", that is, at the water-substrate interface with no solvation of the reaction components. According to the established models of ground-state reactions "on-water", the enhanced efficiency of the photoreactions is explained by hydrophobic effects (Paternó-Büchi reaction) or specific hydrogen bonding (di-π-methane rearrangement) at the water-substrate interface that decrease the energy of the respective transition state. These results point to the potential of this approach to conduct photoreactions more efficiently in an ecologically favorable medium.
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Affiliation(s)
- Robin Schulte
- Department of Chemistry-Biology, Center of Micro- and Nanochemistry and (Bio-)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
| | - Marco Löcker
- Department of Chemistry-Biology, Center of Micro- and Nanochemistry and (Bio-)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
| | - Heiko Ihmels
- Department of Chemistry-Biology, Center of Micro- and Nanochemistry and (Bio-)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
| | - Maximilian Heide
- Department of Chemistry-Biology, Center of Micro- and Nanochemistry and (Bio-)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
| | - Carsten Engelhard
- Department of Chemistry-Biology, Center of Micro- and Nanochemistry and (Bio-)Technology (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57068, Siegen, Germany
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10
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Schramm HM, Tamadate T, Hogan CJ, Clowers BH. Ion-neutral clustering alters gas-phase hydrogen-deuterium exchange rates. Phys Chem Chem Phys 2023; 25:4959-4968. [PMID: 36722872 DOI: 10.1039/d2cp04388b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The rates and mechanisms of chemical reactions that occur at a phase boundary often differ considerably from chemical behavior in bulk solution, but remain difficult to quantify. Ion-neutral interactions are one such class of chemical reactions whose behavior during the nascent stages of solvation differs from bulk solution while occupying critical roles in aerosol formation, atmospheric chemistry, and gas-phase ion separations. Through a gas-phase ion separation technique utilizing a counter-current flow of deuterated vapor, we quantify the degree of hydrogen-deuterium exchange (HDX) and ion-neutral clustering on a series of model chemical systems (i.e. amino acids). By simultaneously quantifying the degree of vapor association and HDX, the effects of cluster formation on reaction kinetics are realized. These results imply that cluster formation cannot be ignored when modeling complex nucleation processes and biopolymer structural dynamics.
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Affiliation(s)
- Haley M Schramm
- Department of Chemistry, Washington State University, Pullman, WA 99163, USA.
| | - Tomoya Tamadate
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Christopher J Hogan
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brian H Clowers
- Department of Chemistry, Washington State University, Pullman, WA 99163, USA.
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11
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Zou H, Shi H, Hao S, Hao Y, Yang J, Tian X, Yang H. Boosting Catalytic Selectivity through a Precise Spatial Control of Catalysts at Pickering Droplet Interfaces. J Am Chem Soc 2023; 145:2511-2522. [PMID: 36652392 DOI: 10.1021/jacs.2c12120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Exploration of new methodologies to tune catalytic selectivity is a long-sought goal in catalytic community. In this work, oil-water interfaces of Pickering emulsions are developed to effectively regulate catalytic selectivity of hydrogenation reactions, which was achieved via a precise control of the spatial distribution of metal nanoparticles at the droplet interfaces. It was found that Pd nanoparticles located in the inner interfacial layer of Pickering droplets exhibited a significantly enhanced selectivity for p-chloroaniline (up to 99.6%) in the hydrogenation of p-chloronitrobenzene in comparison to those in the outer interfacial layer (63.6%) in pure water (68.5%) or in pure organic solvents (46.8%). Experimental and theoretical investigations indicated that such a remarkable interfacial microregion-dependent catalytic selectivity was attributed to the microenvironments of the coexistence of water and organic solvent at the droplet interfaces, which could provide unique interfacial hydrogen-bonding interactions and solvation effects so as to alter the adsorption patterns of p-chloronitrobenzene and p-chloroaniline on the Pd nanoparticles, thereby avoiding the unwanted contact of C-Cl bonds with the metal surfaces. Our strategy of precise spatial control of catalysts at liquid-liquid interfaces and the unprecedented interfacial effect reported here not only provide new insights into the liquid-liquid interfacial reactions but also open an avenue to boost catalytic selectivity.
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Affiliation(s)
- Houbing Zou
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.,Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan 030006, China
| | - Hu Shi
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China
| | - Shijiao Hao
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China
| | - Yajuan Hao
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China
| | - Jie Yang
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China
| | - Xinxin Tian
- Institute of Molecular Science, Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province, Shanxi University, Taiyuan 030006, China.,Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan 030006, China
| | - Hengquan Yang
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.,Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Shanxi University, Taiyuan 030006, China
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12
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Masaya TW, Goulay F. A Molecular Dynamic Study of the Effects of Surface Partitioning on the OH Radical Interactions with Solutes in Multicomponent Aqueous Aerosols. J Phys Chem A 2023; 127:751-764. [PMID: 36639126 DOI: 10.1021/acs.jpca.2c07419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The surface-bulk partitioning of small saccharide and amide molecules in aqueous droplets was investigated using molecular dynamics. The air-particle interface was modeled using a 80 Å cubic water box containing a series of organic molecules and surrounded by gaseous OH radicals. The properties of the organic solutes within the interface and the water bulk were examined at a molecular level using density profiles and radial pair distribution functions. Molecules containing only polar functional groups such as urea and glucose are found predominantly in the water bulk, forming an exclusion layer near the water surface. Substitution of a single polar group by an alkyl group in sugars and amides leads to the migration of the molecule toward the interface. Within the first 2 nm from the water surface, surface-active solutes lose their rotational freedom and adopt a preferred orientation with the alkyl group pointing toward the surface. The different packing within the interface leads to different solvation shell structures and enhanced interaction between the organic molecules and absorbed OH radicals. The simulations provide quantitative information about the dimension, composition, and organization of the air-water interface as well as about the nonreactive interaction of the OH radicals with the organic solutes. It suggests that increased concentrations, preferred orientations, and decreased solvation near the air-water surface may lead to differences in reactivities between surface-active and surface-inactive molecules. The results are important to explain how heterogeneous oxidation mechanisms and kinetics within interfaces may differ from those of the bulk.
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Affiliation(s)
- Tadini Wenyika Masaya
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia26506, United States
| | - Fabien Goulay
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia26506, United States
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13
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Secondary Structure in Amyloids in Relation to Their Wild Type Forms. Int J Mol Sci 2022; 24:ijms24010154. [PMID: 36613597 PMCID: PMC9820225 DOI: 10.3390/ijms24010154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 12/09/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
The amyloid structures and their wild type forms, available in the PDB database, provide the basis for comparative analyses. Globular proteins are characterised by a 3D spatial structure, while a chain in any amyloid fibril has a 2D structure. Another difference lies in the structuring of the hydrogen bond network. Amyloid forms theoretically engage all the NH and C=O groups of the peptide bonds in a chain with two hydrogen bonds each. In addition, the hydrogen bond network is highly ordered-as perpendicular to the plane of the chain. The β-structure segments provide the hydrogen bond system with an anti-parallel system. The folds appearing in the rectilinear propagation of the segment with the β-structure are caused by just by one of the residues in the sequence-residues with a Rα-helical or Lα-helical conformation. The antiparallel system of the hydrogen bonds in the β-structure sections at the site of the amino acid with a Rα- or Lα-helical conformation changes into a parallel system locally. This system also ensures that the involvement of the C=O and H-N groups in the construction of the interchain hydrogen bond, while maintaining a perpendicular orientation towards the plane of the chain. Conformational analysis at the level of the Phi and Psi angles indicates the presence of the conditions for the structures observed in the amyloids. The specificity of amyloid structures with the dominant conformation expressed as |Psi| = |Phi| reveals the system of organisation present in amyloid fibrils. The Phi, Psi angles, as present in this particular structure, transformed to form |Psi| = |Phi| appear to be ordered co-linearly. Therefore, the calculation of the correlation coefficient may express the distribution around this idealised localisation on the Ramachandran map. Additionally, when the outstanding points are eliminated, the part of amyloid chain can be classified as fulfilling the defined conditions. In addition, the presentation of the chain structure using geometric parameters, V-angle-the angle between the planes of the adjacent peptide bonds (angle versus the virtual axis Cα-Cα) and the radius of the curvature R, depending on the size of the angle V, allows for a quantitative assessment of changes during amyloid transformation.
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14
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Jordan CJC, Lowe EA, Verlet JRR. Photooxidation of the Phenolate Anion is Accelerated at the Water/Air Interface. J Am Chem Soc 2022; 144:14012-14015. [PMID: 35900260 PMCID: PMC9376918 DOI: 10.1021/jacs.2c04935] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
![]()
Molecular photodynamics can be dramatically affected
at the water/air
interface. Probing such dynamics is challenging, with product formation
often probed indirectly through its interaction with interfacial water
molecules using time-resolved and phase-sensitive vibrational sum-frequency
generation (SFG). Here, the photoproduct formation of the phenolate
anion at the water/air interface is probed directly using time-resolved
electronic SFG and compared to transient absorption spectra in bulk
water. The mechanisms are broadly similar, but 2 to 4 times faster
at the surface. An additional decay is observed at the surface which
can be assigned to either diffusion of hydrated electrons from the
surface into the bulk or due to increased geminate recombination at
the surface. These overall results are in stark contrast to phenol,
where dynamics were observed to be 104 times faster and
for which the hydrated electron was also a photoproduct. Our attempt
to probe phenol showed no electron signal at the interface.
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Affiliation(s)
- Caleb J C Jordan
- Department of Chemistry, Durham University, Durham, DH1 3LE, United Kingdom
| | - Eleanor A Lowe
- Department of Chemistry, Durham University, Durham, DH1 3LE, United Kingdom
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham, DH1 3LE, United Kingdom
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Speedy at the surface. Nat Rev Chem 2022; 6:302. [PMID: 37117933 DOI: 10.1038/s41570-022-00390-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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