Microencapsulation technology has been increasingly applied toward the development of self-healing paints. Added to paint as a dry powder prior to spraying, the microcapsules store a liquid that can repair the protective barrier layer if released into a scratch. However, self-healing will not occur unless the microcapsules can withstand spray-painting, aggressive solvents in the paint, and long-term exposure to the elements. We have therefore developed a one-pot synthesis for the production of Pickering microcapsules with outstanding strength, solvent resistance, and barrier properties. Octadecyltrimethoxysilane-filled (OTS) microcapsules form via standard interfacial polycondensation, except that silica nanopowder (10-20 nm diameter) replaces the conventional surfactant or hydrocolloid emulsifier. Isophorone diisocyanate (IPDI) in the OTS core reacts with diethylenetriamine, polyethylenimine, and water to form a hard polymer shell along the interface. Compared to pure polyurea, the silica-polyurea composite improves the shelf life of the OTS by 10 times. The addition of SiO2 prevents leaching of OTS into xylenes and hexanes for up to 80 days, and the resulting microcapsules survive nebulization through a spray gun at 620 kPa in a 500 cSt fluid.

The basic cleavages (pH 10) of p-nitrophenyl diphenyl phosphate (1, PNPDPP), p-nitrophenyl 1,8-naphthyl phosphate (2, PNPNP), and p-nitrophenyl biphenyl phosphate (3, PNPBPP) were mediated by α-, β-, and γ-cyclodextrins. Derived kinetic parameters revealed substantial selectivity for the β-CD/PNPNP system, with efficient cyclodextrin-catalyzed cleavage characterized by a high value of k cat/K diss.

[reaction: see text] The copper metallomicellar hydrolysis of O-methyl O-4-nitrophenyl phenylphosphonothioate to O-methyl phenylphosphonothioic acid takes place with effectively complete inversion at phosphorus.

The reactivity exhibited by transition metal complexes depends on the oxidation state of the metal center [1] and on stereoelectronic (steric and electronic) effects of the ligands. [2] Since the initial development of poly(pyrazol-1-yl)alkanes [3] and poly(pyrazol-1-yl)borates [4] by Trofimenko, these socalled ™scorpionate∫ ligands have been used in coordination, organometallic, and bioinorganic chemistry. [5±6] Utilizing these scorpionate ligands and different geometrical arrangements of tridentate ™spectator∫ ligands, we observe a dramatic 1.9 Â 10 7 rate increase for ligand substitution at a supposedly inert ruthenium(ii) center. To explain these unexpected results, ligand substitution kinetics for complexes having different ligand geometries are compared. Scheme 1 depicts two systems, one in which the active site lies in the plane of the [*] Dr.

Stung into action: The largest rate constant to date for ligand substitution at an RuII center (110 M−1 s−1) was observed as a result of a heteroscorpionate ligand effect (see picture; X=H2O, R≠pyrazole, M=Ru) for the substitution of H2O by CH3CN.