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Zhang D, Wang J, Chen H, Gong C, Xing D, Liu Z, Gladich I, Francisco JS, Zhang X. Fast Hydroxyl Radical Generation at the Air-Water Interface of Aerosols Mediated by Water-Soluble PM 2.5 under Ultraviolet A Radiation. J Am Chem Soc 2023; 145:6462-6470. [PMID: 36913682 DOI: 10.1021/jacs.3c00300] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
Abstract
Due to the adverse health effects and the role in the formation of secondary organic aerosols, hydroxyl radical (OH) generation by atmospheric fine particulate matter (PM) has been of particular research interest in both bulk solutions and the gas phase. However, OH generation by PM at the air-water interface of atmospheric water droplets, a unique environment where reactions can be accelerated by orders of magnitude, has long been overlooked. Using the field-induced droplet ionization mass spectrometry methodology that selectively samples molecules at the air-water interface, here, we show significant oxidation of amphiphilic lipids and isoprene mediated by water-soluble PM2.5 at the air-water interface under ultraviolet A irradiation, with the OH generation rate estimated to be 1.5 × 1016 molecule·s-1·m-2. Atomistic molecular dynamics simulations support the counter-intuitive affinity for the air-water interface of isoprene. We opine that it is the carboxylic chelators of the surface-active molecules in PM that enrich photocatalytic metals such as iron at the air-water interface and greatly enhance the OH generation therein. This work provides a potential new heterogeneous OH generation channel in the atmosphere.
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Affiliation(s)
- Dongmei Zhang
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin 300071, China
| | - Jie Wang
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin 300071, China
| | - Huan Chen
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin 300071, China
| | - Chu Gong
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin 300071, China
| | - Dong Xing
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin 300071, China
| | - Ziao Liu
- Department of Earth and Environmental Science and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6316, United States
| | - Ivan Gladich
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34410, Doha, Qatar
| | - Joseph S Francisco
- Department of Earth and Environmental Science and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6316, United States
| | - Xinxing Zhang
- College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin 300071, China
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
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2
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Yuan S, Zhang H, Yuan S. Theoretical insights into the uptake of sulfonamides onto phospholipid bilayers: Mechanisms, interaction and toxicity evaluation. JOURNAL OF HAZARDOUS MATERIALS 2022; 435:129033. [PMID: 35525012 DOI: 10.1016/j.jhazmat.2022.129033] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/13/2022] [Accepted: 04/26/2022] [Indexed: 06/14/2023]
Abstract
Sulfonamides (SAs) are now recognized as the main emerging environmental pollutants in aquatic environments. Although the bioaccumulation capacities of SAs have been confirmed, the pathway for the penetration of the SAs into lipid bilayer has been not fully understood. In this study, the bioaccumulation mechanism of four typical SAs onto the dipalmitoyl phosphatidylcholine (DPPC) lipid bilayer and their effects on the properties of DPPC bilayer were employed and evaluated respectively by using molecular dynamics simulations. Results show that from the viewpoint of thermodynamics, it is favorable for these SAs partitioning to DPPC bilayer. The accommodation of four SAs onto the lipid membrane needs to undergo several processes, which include the contact stage, transformation stage, and absorption stage. Besides, the sulfamethoxazole (SMX) and sulfamethazine (SMZ) show a strong preference for the DPPC phase rather than the interface region while the sulfadiazine (SDZ) and sulfametoxydiazine (SMD) have similar tendencies in the interface region and DPPC phase. Furthermore, the cytotoxicity of SAs is reflected in their ability to affect the electrostatic potential of the membrane and to reduce the thickness of phospholipid bilayers. This molecular-level study provided an insightful understanding of the toxicity and bioaccumulation of SAs.
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Affiliation(s)
- Shideng Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Heng Zhang
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Shiling Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China.
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3
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Wang X, Liu S, Bao L, Zhang H, Yuan S, He M, Yuan S. Enhanced uptake of methacrolein at the acidic nanoparticle interface: Adsorption, heterogeneous reaction and impact for the secondary organic aerosol formation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 800:149532. [PMID: 34426310 DOI: 10.1016/j.scitotenv.2021.149532] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/17/2021] [Accepted: 08/04/2021] [Indexed: 06/13/2023]
Abstract
Considering the moderate acidity of aerosols, the formation of secondary organic aerosols (SOA) through acid-catalyzed heterogeneous reactions has become a recent concern. However, the detailed information on the multiphase chemistry of organic compounds adsorbed onto acidic aerosols remains uncertain. In this work, we investigated the multiphase chemical processes between methacrolein (MACR) and sulfuric acid (SA) and their relationship with SOA formation. Results show that the aqueous nanoparticle interface, especially when it is an acidic nanoparticle interface, is a perfect area to adsorb and accommodate MACR. The occurrence percentage of MACR on the interface is more than 70%. With the increase of SA concentration, the first solvation shell changed from only water to the mixture of SA and water, which facilitates the heterogeneous hydration reaction of MACR. Compared with the neutral nanoparticle interface, the acidic nanoparticle interface exhibits a better ability to uptake and accommodate gaseous carbonyl species. Moreover, SA can catalyze the hydration reaction of MACR inside the aqueous media, and the resulting oligomers contribute to the formation and growth of SOA. The hydration reaction indirectly promotes the continuous adsorption of MACR at the acidic nanoparticle interface. The rate constant shows a positive altitude dependence, and acid-catalyzed reactions have an important impact on environmental chemistry, such as cloud SOA formation, within the range of about 2-6 km. This study reports a complete description of the heterogeneous interactions between unsaturated carbonyl species and acidic nanoparticles by using molecular dynamics and quantum chemistry methods, aiming to provide some insights for the further study on heterogeneous chemistry and its role in the formation of tropospheric SOA.
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Affiliation(s)
- Xueyu Wang
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Shasha Liu
- School of Chemistry and Chemical Engineering, Qilu Normal University, Jinan 250100, China
| | - Lei Bao
- School of Chemical Sciences, University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Heng Zhang
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Shideng Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China
| | - Maoxia He
- Environment Research Institute, Shandong University, Qingdao 266237, China
| | - Shiling Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, China.
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4
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Wang X, Wei Y, Zhang H, Bao L, He M, Yuan S. Understanding the properties of methyl vinyl ketone and methacrolein at the air-water interface: Adsorption, heterogeneous reaction and environmental impact analysis. CHEMOSPHERE 2021; 283:131183. [PMID: 34467940 DOI: 10.1016/j.chemosphere.2021.131183] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/31/2021] [Accepted: 06/07/2021] [Indexed: 06/13/2023]
Abstract
Air-water interfaces are ubiquitous in nature, as manifested in the form of the surfaces of oceans, lakes, and atmospheric aqueous aerosols. The aerosol droplets interface, in particular, plays a critical role in numerous atmospheric chemistry processes. Methyl vinyl ketone (MVK) and methacrolein (MACR), two abundant volatile organic compounds, are the significant precursors of Criegee intermediates and secondary organic aerosol. In this work, the physicochemical properties of MVK and MACR at the air-water interface are studied from a theoretical perspective. The free energy wells of MVK and MACR occur at the air-water interface, and the absorption probabilities of them are 71% and 67%, respectively. Repulsion dominates the interactions between MVK/MACR and water molecules in the bulk region, while attraction is dominant at the interface. The two molecules tend to tilt at the interface, with the CC bond exposed at the outer interface. The most likely reaction scenario of O3-initiated MVK/MACR reaction in the troposphere is also determined for the first time. Based on the molecular dynamics simulation results, the activity sequence of MVK + O3 is given at four different environments by the density functional theory method: air-water interface, mineral clusters interface, bulk solution, and homogeneous gas. The interfacial water molecule can catalyze the reaction of MVK with O3, and the rate constant at the air-water interface is ~6 times larger than that on the mineral surface model. Compared with mineral particles, aqueous particles play a more significant role in modifying the reaction properties of atmospheric organic species.
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Affiliation(s)
- Xueyu Wang
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan, 250100, China
| | - Yaoyao Wei
- School of Chemistry and Chemical Engineering, Linyi University, Linyi, 276000, China
| | - Heng Zhang
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan, 250100, China
| | - Lei Bao
- School of Chemical Sciences, University of the Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Maoxia He
- Environment Research Institute, Shandong University, Qingdao, 266237, China
| | - Shiling Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan, 250100, China.
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5
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Infrared matrix-isolation and theoretical studies of interactions between CH3I and water. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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6
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Gladich I, Abotaleb A, Sinopoli A. Tuning CO 2 Capture at the Gas/Amine Solution Interface by Changing the Solvent Polarity. J Phys Chem B 2020; 124:10245-10256. [PMID: 33140965 DOI: 10.1021/acs.jpcb.0c06340] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Carbon dioxide scrubbing by aqueous amine solution is considered as a promising technology for post-combustion CO2 capture, while mitigating climate change. The lack of physicochemical details for this process, especially at the interface between the gas and the condensed phase, limits our capability in designing novel and more cost-effective scrubbing systems. Here, we present classical and first-principles molecular dynamics results on CO2 capture at the gas/amine solution interfaces using solvents of different polarities. Even if it is apolar, carbon dioxide is absorbed at the gas/monoethanolamine (MEA) aqueous solution interface, forming stable and interfacial [CO2·MEA] complexes, which are the first reaction intermediate toward the chemical conversion of CO2 to carbamate ions. We report that the stability of the interfacial [CO2·MEA] precomplex depends on the nature and polarity of the solution, as well as on the conformer population of MEA. By changing the polarity of the solvent, using chloroform, we observed a shift in the interfacial MEA population toward conformers that form more stable [CO2·MEA] complexes and, at the same time, a further stabilization of the complex induced by the solvent environment. Thus, while lowering the polarity of the solvent could decrease the solubility of MEA, at the same time, it favors conformers that are more prone to CO2 capture and mineralization. The results presented here offer a theoretical framework that helps in designing novel and more cost-effective solvents for CO2 scrubbing systems, while shedding further light on the intrinsic reaction mechanisms of interfacial environments in general.
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Affiliation(s)
- Ivan Gladich
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34110, Doha, Qatar
| | - Ahmed Abotaleb
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34110, Doha, Qatar
| | - Alessandro Sinopoli
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34110, Doha, Qatar
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7
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Zhu C, Zeng XC, Francisco JS, Gladich I. Hydration, Solvation, and Isomerization of Methylglyoxal at the Air/Water Interface: New Mechanistic Pathways. J Am Chem Soc 2020; 142:5574-5582. [PMID: 32091211 DOI: 10.1021/jacs.9b09870] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aqueous-phase processing of methylglyoxal (MG) has been suggested to play a key role in the formation of secondary organic aerosols and catalyze particle growth in the atmosphere. However, the details of these processes remain speculative owing to the lack of a complete description of the physicochemical behavior of MG on atmospheric aerosols. Here, the solvation and hydrolysis of MG at the air/liquid water interface is studied via classical and first-principles molecular dynamics simulations combined with free-energy methods. Our results reveal that the polarity of the water solvent catalyzed the trans-to-cis isomerization of MG at the air/liquid water interface relative to the gas phase. Despite the presence of a hydrophobic group, MG often solvates with both the ketone and methyl groups parallel to the water interface. Analysis of the instantaneous water surface reveals that when MG is in the trans state, the methyl group repels interfacial water to maintain the planarity of the molecule, indicating that lateral and temporal inhomogeneities of interfacial environments are important for fully characterizing the solvation of MG. The counterintuitive behavior of the hydrophobic group is ascribed to a tendency to maximize the number of hydrogen bonds between MG and interfacial water while minimizing the torsional free energy. This drives MG hydration, and our simulations indicate that the formation of MG diol is catalyzed at the air/liquid water interface compared to the gas phase and occurs through nucleophilic attack of water on the carbonyl carbon.
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Affiliation(s)
- Chongqin Zhu
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States.,Department of Earth and Environmental Science and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Xiao Cheng Zeng
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Joseph S Francisco
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States.,Department of Earth and Environmental Science and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Ivan Gladich
- Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825, Doha, Qatar.,European Centre for Living Technology (ECLT), Ca' Bottacin, Dorsoduro 3911, Calle Crosera, 30124 Venice, Italy
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8
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Lv G, Zhang H, Wang Z, Wang N, Sun X, Zhang C, Li M. Understanding the properties of methanesulfinic acid at the air-water interface. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 668:524-530. [PMID: 30856564 DOI: 10.1016/j.scitotenv.2019.03.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/27/2019] [Accepted: 03/03/2019] [Indexed: 06/09/2023]
Abstract
Methanesulfinic acid (MSIA), an organic sulfur compound, is mainly produced in the oxidation process of dimethyl sulfide in the atmosphere. The properties of MSIA at the air-water interface were studied using molecular dynamics (MD) simulations. The result shows that the lowest system free energy is located at the interface. Because the free energy difference between the interface and water phase is 3.2 kJ mol-1, the MSIA molecule can easily get out of the free energy well and travel to water phase by the thermal motion, leading to only a 21% probability of its occurrence at the interface. The MSIA molecule tends to tilt at the interface with the sulfino group (-S(O)-OH) pointing toward the water phase. The feature of hydration status at the air-water interface may be favorable to the heterogeneous oxidation of MSIA.
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Affiliation(s)
- Guochun Lv
- Environment Research Institute, Shandong University, Jinan 250100, China
| | - Heng Zhang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Zehua Wang
- Environment Research Institute, Shandong University, Jinan 250100, China
| | - Ning Wang
- Environment Research Institute, Shandong University, Jinan 250100, China
| | - Xiaomin Sun
- Environment Research Institute, Shandong University, Jinan 250100, China.
| | - Chenxi Zhang
- College of Biological and Environmental Engineering, Binzhou University, Binzhou 256600, China
| | - Mei Li
- Institute of Mass Spectrometer and Atmospheric Environment, Jinan University, Guangzhou 510632, China; Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangzhou 510632, China.
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9
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Foley CD, Joalland B, Alavi ST, Suits AG. Mixed transitions in the UV photodissociation of propargyl chloride revealed by slice imaging and multireference ab initio calculations. Phys Chem Chem Phys 2018; 20:27474-27481. [DOI: 10.1039/c8cp04596h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Resonance-enhanced multiphoton ionization (REMPI) and DC slice imaging were used to detect photoproducts Cl (2P3/2), spin–orbit excited Cl* (2P1/2), and C3H3 in the photodissociation of propargyl chloride at 212 and 236 nm.
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Affiliation(s)
- Casey D. Foley
- Department of Chemistry
- University of Missouri
- Columbia
- USA
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10
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Abstract
Whisky is distilled to around 70% alcohol by volume (vol-%) then diluted to about 40 vol-%, and often drunk after further slight dilution to enhance its taste. The taste of whisky is primarily associated with amphipathic molecules, such as guaiacol, but why and how dilution enhances the taste is not well understood. We carried out computer simulations of water-ethanol mixtures in the presence of guaiacol, providing atomistic details on the structure of the liquid mixture. We found that guaiacol is preferentially associated with ethanol, and, therefore, primarily found at the liquid-air interface in mixtures that contain up to 45 vol-% of ethanol. At ethanol concentrations of 59 vol-% or higher, guaiacol is increasingly surrounded by ethanol molecules and is driven to the bulk. This indicates that the taste of guaiacol in the whisky would be enhanced upon dilution prior to bottling. Our findings may apply to other flavour-giving amphipathic molecules and could contribute to optimising the production of spirits for desired tastes. Furthermore, it sheds light on the molecular structure of water-alcohol mixtures that contain small solutes, and reveals that interactions with the water may be negligible already at 89 vol-% of ethanol.
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11
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Martins‐Costa MTC, Anglada JM, Ruiz‐López MF. Computational Insights into the CH
3
Cl+OH Chemical Reaction Dynamics at the Air–Water Interface. Chemphyschem 2017; 18:2747-2755. [DOI: 10.1002/cphc.201700437] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 06/02/2017] [Indexed: 11/11/2022]
Affiliation(s)
| | - Josep M. Anglada
- Departament de Química Biològica i Modelització MolecularIQAC, CSIC c/ Jordi Girona 18 E-08034 Barcelona Spain
| | - Manuel F. Ruiz‐López
- SRSMCUniversity of Lorraine and CNRS Boulevard des Aiguillettes, BP 70239 54506 Vandoeuvre-lès-Nancy France
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12
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Vereecken L, Glowacki DR, Pilling MJ. Theoretical Chemical Kinetics in Tropospheric Chemistry: Methodologies and Applications. Chem Rev 2015; 115:4063-114. [DOI: 10.1021/cr500488p] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Luc Vereecken
- Max Planck Institute for Chemistry, 55128 Mainz, Germany
| | - David R. Glowacki
- PULSE
Institute and Department of Chemistry, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- School
of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
- Department
of Computer Science, University of Bristol, Bristol BS8 1UB, United Kingdom
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13
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Lin W, Clark AJ, Paesani F. Effects of surface pressure on the properties of Langmuir monolayers and interfacial water at the air-water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:2147-2156. [PMID: 25642579 DOI: 10.1021/la504603s] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The effects of surface pressure on the physical properties of Langmuir monolayers of palmitic acid (PA) and dipalmitoylphosphatidic acid (DPPA) at the air/water interface are investigated through molecular dynamics simulations with atomistic force fields. The structure and dynamics of both monolayers and interfacial water are compared across the range of surface pressures at which stable monolayers can form. For PA monolayers at T = 300 K, the untilted condensed phase with a hexagonal lattice structure is found at high surface pressure, while the uniformly tilted condensed phase with a centered rectangular lattice structure is observed at low surface pressure, in agreement with the available experimental data. A state with uniform chain tilt but no periodic spatial ordering is observed for DPPA monolayers on a Na(+)/water subphase at both high and low surface pressures. The hydrophobic acyl chains of both monolayers pack efficiently at all surface pressures, resulting in a very small number of gauche defects. The analysis of the hydrogen-bonding structure/dynamics at the monolayer/water interface indicates that water molecules hydrogen-bonded to the DPPA head groups reorient more slowly than those hydrogen-bonded to the PA head groups, with the orientational dynamics becoming significantly slower at high surface pressure. Possible implications for physicochemical processes taking place on marine aerosols in the atmosphere are discussed.
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Affiliation(s)
- Wei Lin
- Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093, United States
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