Fragmentation and reactivity in collisions of protonated diglycine with chemically modified perfluorinated alkylthiolate-self-assembled monolayer surfaces

Journal Article · Mon Mar 07 00:00:00 EST 2011 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3558736· OSTI ID:21560039

Barnes, George L; Li, Yang; Hase, William L ^[1]; Young, Kelsey ^[2]

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1. Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409 (United States)
2. Department of Chemistry and Biochemistry, Abilene Christian University, Abilene, Texas 79699 (United States)

Direct dynamics simulations are reported for quantum mechanical (QM)/molecular mechanical (MM) trajectories of N-protonated diglycine (gly{sub 2}-H{sup +}) colliding with chemically modified perfluorinated octanethiolate self-assembled monolayer (SAM) surfaces. The RM1 semiempirical theory is used for the QM component of the trajectories. RM1 activation and reaction energies were compared with those determined from higher-level ab initio theories. Two chemical modifications are considered in which a head group (-COCl or -CHO) is substituted on the terminal carbon of a single chain of the SAM. These surfaces are designated as the COCl-SAM and CHO-SAM, respectively. Fragmentation, peptide reaction with the SAM, and covalent linkage of the peptide or its fragments with the SAM surface are observed. Peptide fragmentation via concerted CH{sub 2}-CO bond breakage is the dominant pathway for both surfaces. HCl formation is the dominant species produced by reaction with the COCl-SAM, while for the CHO-SAM a concerted H-atom transfer from the CHO-SAM to the peptide combined with either a H-atom or radical transfer from the peptide to the surface to form singlet reaction products is the dominant pathway. A strong collision energy dependence is found for the probability of peptide fragmentation, its reactivity, and linkage with the SAM. Surface deposition, i.e., covalent linkage between the surface and the peptide, is compared to recent experimental observations of such bonding by Laskin and co-workers [Phys. Chem. Chem. Phys. 10, 1512 (2008)]. Qualitative differences in reactivity are seen between the COCl-SAM and CHO-SAM showing that chemical identity is important for surface reactivity. The probability of reactive surface deposition, which is most closely analogous to experimental observables, peaks at a value of around 20% for a collision energy of 50 eV.

• OSTI ID: 21560039
• Journal Information: Journal of Chemical Physics, Vol. 134, Issue 9; Other Information: DOI: 10.1063/1.3558736; (c) 2011 American Institute of Physics; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOMS
BONDING
CARBON
COVALENCE
DEPOSITION
DISSOCIATION
ENERGY DEPENDENCE
FRAGMENTATION
HYDROCHLORIC ACID
ION-MOLECULE COLLISIONS
PEAKS
PEPTIDES
PROBABILITY
QUANTUM MECHANICS
REACTION KINETICS
REACTIVITY
SIMULATION
SURFACES
CHLORINE COMPOUNDS
COLLISIONS
ELEMENTS
FABRICATION
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
INORGANIC COMPOUNDS
ION COLLISIONS
JOINING
KINETICS
MECHANICS
MOLECULE COLLISIONS
NONMETALS
ORGANIC COMPOUNDS
PROTEINS