Novel halogen and interhalogen adducts of nanoscale magnesium oxide.

The difference in the adsorption properties of magnesium oxide in two different physical forms--large micron-sized crystals (CM-MgO) and nanoscale crystals (AP-MgO)--is described. The highly energetic surface of the nanoparticles is significantly more active than the bulk surface in adsorption of nonpolar halogens (Cl(2), Br(2), and I(2)) and dipole interhalogen molecules (ICl, IBr, and ICl(3)). The nanocrystalline and microcrystalline MgO adducts with halogens and interhalogens were characterized by thermogravimetric analysis (TGA), UV-vis and Raman spectroscopies, and transmission electron microscopy (TEM). The bonds of the adsorbates were considerably strained upon adsorption on the nanocrystalline MgO without a molecular dissociation. The results presented in the paper explain the enhanced reactivities of the nanoscale MgO, halogen adducts as halogenating agents of organic molecules and their noticeable biocidal activity.