Intramolecular H-bond stabilization of a primary hydroxylamine in salen-type metal complexes.

Primary hydroxylamines, RNHOH, decompose readily in the presence of transition metal ions. We show that this reactivity can be arrested by ligand design via an intramolecular hydrogen bond. Six metal complexes with an intact NHOH group were synthesized and crystallographically characterized. The Cu-hydroxylamine complexes can catalyze the aerobic oxidation of benzylic alcohols.

Colloidal chemistry with patchy silica nanoparticles.

We report a new route to synthesize clusters, or so-called colloidal molecules (CMs), which mimic the symmetry of molecular structures made of one central atom. We couple site-specifically functionalized patchy nanoparticles, i.e., valence-endowed colloidal atoms (CAs), with complementary nanospheres through amide bonds. By analogy with the Gillespie formalism, we show that AX4, AX3E1 and AX2E2 CMs can be obtained from tetravalent sp3-like CAs when the relative amount of both building units is varied in a controlled manner. We obtain AX2 CMs from divalent sp-like CAs. We also show that it is possible to covalently attach two different types of satellites to the same central patchy nanoparticle to create more complex CMs, opening the way to the fabrication of new multifunctional nanostructures with well-controlled shape and composition.

Colloidal Molecules from Valence-Endowed Nanoparticles by Covalent Chemistry.

We demonstrate a simple method to create a variety of silica-based colloidal molecules through the covalent assembly of site-specifically functionalized patchy nanoparticles with complementary nanospheres. Colloidal analogues of BeBr2 , BBr3 and CBr4 are obtained from sp-, sp2 - and sp3 -like particles, while Br2 O and NBr3 analogues can be fabricated by varying the relative amounts of both colloidal precursors. We also show that it is possible to attach covalently silica nanospheres of various sizes to one central patchy nanoparticle, which leads to the formation of more complex colloidal molecules, including chiral ones. The possibility to easily extend the strategy to other colloidal precursors which can serve as satellites, for example, ellipsoidal polymer particles or metallic nanoparticles, opens the way to a rich variety of new colloidal analogues of atoms which could serve as building blocks of next generation materials.