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Abstract: A series of quaternary ammonium functionalized. silicates surface imprinted with the soman hydrolysis product pinacolyl methylphosphonate (PMP) were formed in a one-pot procedure. The formation and adsorption properties of these materials were dependent on the alkyl chain length of the quaternary amine. Brunauer-Emmett-Teller analysis and transmission electron microscopy revealed that silicates formed with added quaternary amine functionalized organosilanes with 10 and 14 carbon hydrocarbon segments (N,N-didecyl-N-methyl-N-(3- trimethoxysilylpropyl)ammonium chloride (DDMAC) and N- tetradecyl-N,N-dimethyl-N-(3-trimethoxysilylpropyl)ammonium chloride (TDDMAC), respectively) formed xerogels with surface areas of 630-712 m(2)/g and broad pore size distributions. The silicate that formed in the presence of a quaternary ammonium functionalized organosilane with an 18 carbon alkyl chain (N- octadecyl-N,N-dimethyl-N-(3-trimethoxysilylpropyl)ammonium chloride (ODDMAC)) formed a microporous silicate with a lower surface area. Addition of PMP during synthesis did not affect the formation or adsorption properties of the DDMAC or TDDMAC silicates but resulted in an ODDMAC silicate with a higher surface area. Significant differences in the adsorption capacities and equilibrium binding constants of ODDMAC silicates formed with and without PMP were observed. This material demonstrated selectivity for small organophosphonate monoesters over a bulkier organophosphonate monoester, diester, and methyl parathion