Bambusuril-based receptors have been used in conjunction with H-1 NMR spectroscopy to recognize mixtures of inorganic anions in aqueous solutions. This was achieved by examining complexationinduced changes in the receptors' H-1 NMR fingerprints. This approach enables the simultaneous identification of up to 9 anions and the quantification of up to 5 anions using a single receptor in DMSO-d(6) containing 5% D2O. Toxic perchlorate was recognized and quantified at 0.1 mu M (1.8 ppb, mol mol(-1)) concentration in pure water.
We report an intraparticle surface plasmon coupling in Au nanorod structures consisting of half smooth and half nanoporous surface morphology; the relative ratio and the diameter difference between each block were important in determining the overall optical properties of such nanostructures.
The gene btrR from Bacillus circulans has been cloned and expressed and shown to produce a protein which catalyses the transamination of 2-deoxy-scyllo-inosose to give 2-deoxy-scyllo-inosamine, an intermediate in the biosynthesis of 2-deoxystreptamine.
Rapid progress on the catalytic mechanism and substrate recognition by squalene-hopene cyclase, which has occurred only in the last several years, is reported. A series of site-directed mutation experiments and some squalene analogues have provided deep insight into the polycyclization mechanism and catalytic sites in conjunction with the information from X-ray crystal data.
Locked nucleic acid (LNA), a recently introduced nucleic acid analogue with a bicyclic 2′-O,4′-C-methylene linked furanose sugar, exhibits enhanced affinities for DNA and RNA relative to the corresponding oligodeoxyribonucleotides and oligoribonucleotides; we report the first crystal structure of an LNA unit incorporated in an oligonucleotide duplex. The structure at 1.4 A resolution of the DNA–LNA decamer duplex with one LNA thymine monomer per strand provides a detailed view of the conformation and hydration of locked nucleic acid residues in a duplex A-form.
Cytochrome c (horse heart) has been adsorbed onto a range of mesoporous silicate materials with the extent of adsorption dependent on the silicate pore size; adsorption and activity profiles of the adsorbed protein are reported.
Incubation of squalene with the site-directed mutant of Ile261Ala of squalene-hopene cyclase from Alicyclobacillus acidocaldarius afforded multiple triterpenes consisting of tri-, tetra- and penta-cyclic skeletons, together with a final product of hopene, among which the previously unknown 6/6/6/6-fused tetracyclic skeletal compounds, denoted prohopene A and B, are included.
Incubation of squalene with the site-directed mutant F605A of squalene–hopene cyclase from Alicyclobacillus acidocaldarius yielded many triterpenes consisting of the 6/6/5-fused tri-, 6/6/6/5-fused tetra-, and 6/6/6/6/5-fused pentacyclic skeletons, the function of F605 being assignable for facilitating the ring expansion and for stabilizing the hopanyl C22-cation, possibly via cation-π interactions.
A catalytically active, bimetallic Pd–allyl complex of the Trost modular ligand, for which X-ray crystallography reveals a tetradentate ('POPO') coordination mode, induces a memory effect in Pd-catalysed allylic alkylation.
2-Substituted (6a-e) and 2, 2-disubstituted oxapenams (6f-g) are obtained in one step by thermolysis of the beta-lactam-based oxazolidinone 4 in the presence of aldehydes and reactive ketones respectively; the C(6)-substituted oxazolidinone variant 7 reacts with hexafluoroacetone to give the enantiomerically pure oxapenam 8.
Dehydrogenation reaction between AlH3←NMe3 and ButP[N(H)But]2 leads to ButP(NBut)2AlH←NMe3, the first neutral 1,3,2,4-diazaphosphaaluminetidine.
Cytochrome P-450 from Bacillus megaterium catalyses the diastereoselective hydroxylations of 13-hydroxymyristic acid, to predominantly erythro-12,13-dihydroxymyristic acid, and of 12-hydroxymyristic acid to give predominantly threo-12,13-dihydroxymyristic acid, in reactions that are stereocomplementary and with considerable potential application in biotransformations.
The deprotonation of [FeIII(N4Py)(η1-OOH)]2+ 1 gives [FeIII(N4Py)(η2-OO)]+ 2, as unequivocally demonstrated by resonance Raman spectroscopy, and leads to the loss of alkane hydroxylation activity by 1.
Two bicyclic products were accumulated by the mutant F365A, showing the amino acid residue is located close to the transient C-8 carbocation intermediate in the active site cavity; the mutants of F365Y and F365W significantly accelerated the cyclization reaction at low temperatures.
The utility of the cis-MCl2... HN+ chelated hydrogen bond as a synthon in preparation of crystalline [4,4'-H(2)bipy][MCl4] (M = Pd 1, Pt 2) is demonstrated; the structure of 2 contains anions and cations linked by hydrogen bonds to form a ribbon polymer.
First row transition metal (M = Mn–Ni) dichlorides react with cyanomanganese(I) carbonyl ligands to give novel paramagnetic bi- and poly-nuclear cyanide-bridged complexes, X-ray structural studies on which are consistent with FeIIIMnI, FeIIIMnII and MnIIMnII core oxidation states for [Cl3M(µ-NC)Mn(CO)(dppm)2]z (M = Fe, z = 0, 1; M = Mn, z = 0) respectively; FeIIIMnI complexes show strong solvatochromism, consistent with low spin d6 octahedral MnI to tetrahedral d5 FeIII charge transfer.
N-Boc 3-hydroxypyrrolidine 1 undergoes directed C-lithiation at C5 and not, as previously reported, at C2; the resulting dilithiated intermediate 6 has been trapped by a range of electrophiles to give 2-substituted 4-hydroxypyrrolidines 7.
Anionic ring-opening polymerisation of spiro[cyclopropane-1,9′-fluorene] with fluorenyl anion as initiator yields polymers 1 with chains which are essentially all-anti and have transversely-oriented fluorenyl groups, as shown by strong upfield shifts for the mid-chain methylene and 1,8-fluorenyl protons; synthetic routes to some specific oligomers are also reported.
