A question of coordination mode : Two new borane compounds are prepared. They act as bifunctional ligands as illustrated by their reaction with ruthenium polyhydrides which leads to the formation of two complexes (see scheme) displaying either a δ‐agostic interaction of a η2‐B? H bond involving a trivalent boron atom or a dihydroborate ligation.
Taking shortcuts : A remarkably short and high‐yielding asymmetric total synthesis of (?)‐oseltamivir takes advantage of organocatalysis and single‐pot domino operations. The target, known as the drug Tamiflu, is prepared efficiently in a short time, and also its derivatives can be synthesized effectively.
Mark us bent! The synthesis, structure, and single‐ and two‐photon spectroscopic properties of a series of pyrimidine‐based (bent‐shaped) molecules are reported. These allow structure‐property relationships and guidelines for both the development and application of TPA compounds to be derived.
Three attractions in one cage : Various magnetic networks are formed in the three polymorphs of an organic magnet, BBTDA(=benzo[1,2‐d:4,5‐d′]bis[1,3,2]dithiazole)?GaBr4. The three phases show quite different magnetic behaviors in spite of having the same chemical formula. Their magnetic differences originate from the relative configuration of the neighboring organic radical molecules in their crystals.
A dramatic increase in the photostability of a blue‐light‐emitting polymer, poly(9,9‐dioctylfluorene), was achieved by the addition of 5–10 nm gold nanoparticles. The optical absorption band of the gold nanoparticles was tuned to resonate the triplet exciton ground state bandgap energy of the polymer. Photo‐oxidation rate of poly(9,9‐dioctylfluorene) was effectively reduced by doping the polymer with very small amounts (≈10−6–10−5 volume fraction) of the gold nanoparticles.
Retarded photo‐oxidation in PDOF nanocomposite films with various doped gold nanoparticles. 相似文献
Chiral 1,2‐diols have been prepared from α‐aminoxylated aldehydes or cyclohexanone and Grignard reagents with L ‐proline or its tetrazole derivative as the catalyst. The presence of the ate complex of CeCl3?2 LiCl is essential for the high overall yields and good selectivities (see scheme; DMSO=dimethyl sulfoxide, THF=tetrahydrofuran, Tol=tolyl).
Perlen auf Gold : Neuartige multifunktionelle Nanopartikel bestehen aus einzelnen Amin‐modifizierten Goldnanostäbchen, an denen Fe3O4‐„Perlen“ mit Carboxyendgruppe angebracht sind. Die Partikel eignen sich zur simultanen Erkennung, dualen Bildgebung und photothermischen Ablation von Brustkrebszellen.
Catalytic convenience : The use of iridium or ruthenium catalysts for C? H bond activation has led to the addition reaction of trifluoromethylated compounds to alkenes (see scheme). This atom‐economical reaction occurs under neutral reaction conditions and without the formation of undesired defluorinated by‐products, even at high temperature.
Oxidizing gold? A gold(I)/gold(III) catalytic cycle is essential for the first oxidative cross‐coupling reaction in gold catalysis. By using Selectfluor for gold(I) oxidation, this chemistry reveals the synthetic potential of incorporating gold(I)/gold(III) catalytic cycles into contemporary gold chemistry and promises a new area of gold research by merging powerful gold catalysis and oxidative metal‐catalyzed cross‐coupling reactions.
Quality control : The incorporation of a wrong amino acid into a growing polypeptide chain induces a correction step in which the release factor (RF1) hydrolyzes the peptide from the incorrectly matched peptidyl‐tRNA (see picture). The nascent erroneous polypeptide is released from the ribosome and degraded.
Collisional activation demonstrates that the stable ions from o-nitrobenzaldehydedimethylacetale possess the structure of ionized o-nitroso benzoic acid methyl ester. Contrary to previous conclusions it is demonstrated that the structure of the stable ions (m/e 135) from different precursors [i.e. o-nitrobenzyl alcohol o-nitrobenzyl cyanide and o-nitrobenzaldoxime is best represented by 2,1-benzisoxazoline-3-one. Ionized o-nitrosobenzaldehtde rearranged to 2,1-benzisoxazoline-3-one prior to collision induced decomposition, whereas 2-benzoxazolinone and 3-hydroxy-1,2-benzisoxazole do not rearrange within 10?5 s. 相似文献
Now you bind it—now you don't! Chemical degradation of a dendritic scaffold allows multivalent interactions with DNA to be “switched off” as the multivalent array of ligands breaks down into smaller fragments, offering an approach by which a molecule can be temporarily endowed with high affinity for a biological target—an important concept in the development of new synthetic systems to intervene in biological pathways.
Synergy in synthesis : Strategic consideration of metathesis and Suzuki–Miyaura (SM) cross‐coupling for C? C bond‐formation processes has opened up new and “green” synthetic routes to various complex targets. The use of this synergistic combination for the synthesis of supramolecular ligands, polyaromatic compounds, and complex natural products is covered in this Focus Review.
Ordered water : Gypsum has been used for construction for millennia. The structure and water content of calcined gypsum, CaSO4?0.5 H2O, has been under discussion until now: single‐crystal structure analysis (see picture: S yellow, Ca gray, O blue, H red) provides an ordered model that is confirmed by DFT calculations.
Additional cyclization : Dicyanonitrosomethanide, [C(CN)2(NO)]? undergoes nucleophilic addition and cyclization of 1,2‐diaminoethane and 1,3‐diaminopropane on the nitrile groups to form imidazolinyl and 1,4,5,6‐tetrahydropyrimidinyl groups, respectively. Ethanolamine has lower reactivity and fails to cyclize.
