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Amphiphile self-assembly dynamics at the solution-solid interface reveal asymmetry in head/tail desorption

CastilloThese authors contributed equally to this work., Henry D., Espinosa-Duran, John M., Dobscha, James R., AshleyCurrent address: Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, USA., Daniel C., Debnath, Sibali, HirschCurrent address: Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven-University of Leuven Celestijnenlaan 200F, 3001 Leuven, Belgium., Brandon E., SchreckeCurrent address: Department of Chemistry, Texas A&M University, College Station, Texas 77840, USA., Samantha R., BaikCurrent address: Department of Chemistry, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu Daejeon, 34141, Republic of Korea., Mu-Hyun, Ortoleva, Peter J., Raghavachari, Krishnan, Flood, Amar H., Tait, Steven L.
Chemical communications 2018 v.54 no.72 pp. 10076-10079
adsorption, asymmetry, chemical compounds, chemical reactions, desorption, graphene, molecular dynamics, molecular weight, scanning tunneling microscopy, solvents, surfactants
Amphiphilic alkoxybenzonitriles (ABNs) of varying chain length are studied at the solution/graphite interface to analyze dynamics of assembly. Competitive self-assembly between ABNs and alkanoic acid solvent is shown by scanning tunneling microscopy (STM) to be controlled by concentration and molecular size. Molecular dynamics (MD) simulations reveal key roles of the sub-nanosecond fundamental steps of desorption, adsorption, and on-surface motion. We discovered asymmetry in desorption–adsorption steps. Desorption starting from alkyl chain detachment from the surface is favored due to dynamic occlusion by neighbouring chains. Even though the nitrile head has a strong solvent affinity, it more frequently re-adsorbs following a detachment event.