Evaluation of the Potential of Modified Calcium Carbonate as a Carrier for Unsaturated Fatty Acids in Oxygen Scavenging Applications.

Modified calcium carbonates (MCC) are inorganic mineral-based particles with a large surface area, which is enlarged by their porous internal structure consisting of hydroxyapatite and calcium carbonate crystal structures. Such materials have high potential for use as carriers for active substances such as oxygen scavenging agents. Oxygen scavengers are applied to packaging to preserve the quality of oxygen-sensitive products.

Molecular Electronic Coupling Controls Charge Recombination Kinetics in Organic Solar Cells of Low Bandgap Diketopyrrolopyrrole, Carbazole, and Thiophene Polymers.

Low-bandgap diketopyrrolopyrrole- and carbazole-based polymer bulk-heterojunction solar cells exhibit much faster charge carrier recombination kinetics than that encountered for less-recombining poly(3-hexylthiophene). Solar cells comprising these polymers exhibit energy losses caused by carrier recombination of approximately 100 mV, expressed as reduction in open-circuit voltage, and consequently photovoltaic conversion efficiency lowers in more than 20%. The analysis presented here unravels the origin of that energy loss by connecting the limiting mechanism governing recombination dynamics to the electronic coupling occurring at the donor polymer and acceptor fullerene interfaces.

Quenching dynamics in CdSe nanoparticles: surface-induced defects upon dilution.

We have analyzed the decays of the fluorescence of colloidal CdSe quantum dots (QDs) suspensions during dilution and titration by the ligands. A ligand shell made of a combination of trioctylphosphine (TOP), oleylamine (OA), and stearic acid (SA) stabilizes the as-synthesized QDs. The composition of the shell was analyzed and quantified using high resolution liquid state 1H nuclear magnetic resonance (NMR) spectroscopy.

Chemoselectivity as a delineator of cuprate structure in catalytic 1,4-addition of diorganozinc reagents to Michael acceptors.

Reaction of the cyclic thioacetal (RS)(2)CHCHO [R=1/2 x -(CH(2))(3)-] with HCCCOMe, followed by treatment with TsCl/DABCO (Ts=tosyl, DABCO=1,4-diazabicyclo[2.2.2]octane) affords the mono-protected 1,4-benzoquinone dithioacetal.

Tandem reactions with chiral enolates: preparation of allylic alcohols via trapping with vinyl oxiranes.

An opening of vinyl oxiranes has been accomplished with Zn and Al enolates resulting from asymmetric conjugate addition reactions on cyclic enones. This novel tandem procedure affords the adducts in moderate to good yields, enantioselectivities up to 98%, and moderate to good cis/trans selectivities. This provides potentially useful synthetic substrates to prepare complex bicyclic compounds.