Immobilization of volatile and corrosive iodine monochloride (ICl) and I(2) reagents in a stable metal-organic framework.

Abstract

The major discovery here is a robust and water-stable metal-organic framework (MOF) material capable of reversible binding of the volatile and reactive molecules of ICl and I2. The immobilization of I2 and ICl, as well as their controllable release thus achieved, is to facilitate the wide-ranging applications of these volatile species as catalysts and reagents in chemical and industrial processes. The framework material TMBP·CuI (hereafter TCuI) can be conveniently prepared in quantitative yields by heating CuI and the organic linker TMBP (3,3',5,5'-tetramethyl-4,4'-bipyrazol) in acetonitrile. The microporous three-dimensional net of TCuI features CuI chains that contribute to efficient and reversible binding of ICl and I2 molecules, to result in the stoichiometrically well-defined adducts of TCuI·ICl and TCuI·I2, respectively. Moreover, the confinement of a volatile compound like ICl within the MOF medium provides unique opportunities to enhance its reactivity and selectivity as a chemical reagent, as is exemplified by the iodination reactions examined herein. With this exemplary study, we intend to stimulate interest in further exploring MOFs and other porous media (e.g., porous polymers) for entrapping ICl and other volatile reagents (e.g., Br2, SCl2, S2Cl2, and SOCl2) and for potentially novel reactivity associated with the porous medium.