Chemical Warfare Agent Surface Adsorption: Hydrogen Bonding of Sarin and Soman to Amorphous Silica.

Sarin and soman are warfare nerve agents that represent some of the most toxic compounds ever synthesized. The extreme risk in handling such molecules has, until now, precluded detailed research into the surface chemistry of agents. We have developed a surface science approach to explore the fundamental nature of hydrogen bonding forces between these agents and a hydroxylated surface. Infrared spectroscopy revealed that both agents adsorb to amorphous silica through the formation of surprisingly strong hydrogen-bonding interactions with primarily isolated silanol groups (SiOH). Comparisons with previous theoretical results reveal that this bonding occurs almost exclusively through the phosphoryl oxygen (P═O) of the agent. Temperature-programmed desorption experiments determined that the activation energy for hydrogen bond rupture and desorption of sarin and soman was 50 ± 2 and 52 ± 2 kJ/mol, respectively. Together with results from previous studies involving other phosphoryl-containing molecules, we have constructed a detailed understanding of the structure-function relationship for nerve agent hydrogen bonding at the gas-surface interface.

[1]  W. Gordon,et al.  Multifunctional ultra-high vacuum apparatus for studies of the interactions of chemical warfare agents on complex surfaces. , 2014, The Review of scientific instruments.

[2]  Teri Lalain,et al.  Infrared Spectra and Binding Energies of Chemical Warfare Nerve Agent Simulants on the Surface of Amorphous Silica , 2013 .

[3]  D. Troya,et al.  Theoretical Study of the Adsorption of Organophosphorous Compounds to Models of a Silica Surface , 2013 .

[4]  DeCarlos E. Taylor,et al.  Surface binding of organophosphates on silica: Comparing experiment and theory , 2013 .

[5]  J. Uzarski,et al.  Interactions and binding energies of dimethyl methylphosphonate and dimethyl chlorophosphate with amorphous silica. , 2012, Langmuir : the ACS journal of surfaces and colloids.

[6]  A. V. Duin,et al.  Reactive Molecular Dynamics Studies of DMMP Adsorption and Reactivity on Amorphous Silica Surfaces , 2010 .

[7]  Donna A. Chen,et al.  Dimethyl methylphosphonate decomposition on fully oxidized and partially reduced ceria thin films , 2010 .

[8]  B. D. Kay,et al.  Adsorption, desorption, and diffusion of nitrogen in a model nanoporous material. I. Surface limited desorption kinetics in amorphous solid water. , 2007, The Journal of chemical physics.

[9]  Victor M. Bermudez,et al.  Computational Study of the Adsorption of Trichlorophosphate, Dimethyl Methylphosphonate, and Sarin on Amorphous SiO2 , 2007 .

[10]  John R. Morris,et al.  Adsorption and Decomposition of Dimethyl Methylphosphonate on Y2O3 Nanoparticles , 2007 .

[11]  L. T. Zhuravlev.  Concentration of hydroxyl groups on the surface of amorphous silicas , 1987 .

[12]  J. White,et al.  A TPD/AES study of the interaction of dimethyl methylphosphonate with iron oxide (.alpha.-Fe2O3) and silicon dioxide , 1986 .

[13]  S. Bauer,et al.  Spectroscopic Studies of the Hydrogen Bond. II. The Shift of the O–H Vibrational Frequency in the Formation of the Hydrogen Bond , 1937 .