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J Phys Chem A

Title:		Molecular modeling of the green leaf volatile methyl salicylate on atmospheric air/water interfaces
Author(s):		Liyana-Arachchi TP; Hansel AK; Stevens C; Ehrenhauser FS; Valsaraj KT; Hung FR;
Address:		"Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, USA"
Journal Title:		J Phys Chem A
Year:		2013
Volume:		20130521
Issue:		21
Page Number:		4436 - 4443
DOI:		10.1021/jp4029694
ISSN/ISBN:		1520-5215 (Electronic) 1089-5639 (Linking)
Abstract:		"Methyl salicylate (MeSA) is a green leaf volatile (GLV) compound that is emitted in significant amounts by plants, especially when they are under stress conditions. GLVs can then undergo chemical reactions with atmospheric oxidants, yielding compounds that contribute to the formation of secondary organic aerosols (SOAs). We investigated the adsorption of MeSA on atmospheric air/water interfaces at 298 K using thermodynamic integration (TI), potential of mean force (PMF) calculations, and classical molecular dynamics (MD) simulations. Our molecular models can reproduce experimental results of the 1-octanol/water partition coefficient of MeSA. A deep free energy minimum was found for MeSA at the air/water interface, which is mainly driven by energetic interactions between MeSA and water. At the interface, the oxygenated groups in MeSA tend to point toward the water side of the interface, with the aromatic group of MeSA lying farther away from water. Increases in the concentrations of MeSA lead to reductions in the height of the peaks in the MeSA-MeSA g(r) functions, a slowing down of the dynamics of both MeSA and water at the interface, and a reduction in the interfacial surface tension. Our results indicate that MeSA has a strong thermodynamic preference to remain at the air/water interface, and thus chemical reactions with atmospheric oxidants are more likely to take place at this interface, rather than in the water phase of atmospheric water droplets or in the gas phase"
Keywords:		"Air Atmosphere/*chemistry Models, Molecular Molecular Dynamics Simulation Plant Leaves/*chemistry Salicylates/*chemistry Surface Properties Water/chemistry;"
Notes:		"MedlineLiyana-Arachchi, Thilanga P Hansel, Amie K Stevens, Christopher Ehrenhauser, Franz S Valsaraj, Kalliat T Hung, Francisco R eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2013/05/15 J Phys Chem A. 2013 May 30; 117(21):4436-43. doi: 10.1021/jp4029694. Epub 2013 May 21"