Complete synthesis of serratamolide

Summary The complete synthesis of the antibiotic serratamolide has been effected, definitively demonstrating its structure.Khimiya Prirodnykh Soedinenii, Vol. 3, No. 4, pp. 267–272, 1967     

Complete synthesis of angolide

Summary The structure of angolide — a depsipeptide produced by one of the strains of Pithomyces — has been established and its complete synthesis has been effected.Khimiya prirodnykh soedinenii, Vol. 1, No. 1, pp. 58–62, 1965     

Complete synthesis of the antibiotic anisomycin

The synthesis of the antibiotic anisomycin ( 1 ) is described. In the key step 3, 4-dimethoxy-thiopyrrolidone ( 16 ), prepared from diethyl L -( + )-tartarate ( 4 ) was converted to the thioiminoester 18 , which upon treatment with trimethylphosphite yielded the benzylidene derivative 19 . Cleavage of the ester group of 19 and hydrogenation of the decarboxylation product gave the two isomers 21 and 22 . 22 was converted into desacetylanisomycin ( 3 ) and anisomycin ( 1 ).     

Complete stereochemistry of tetrafibricin

With use of the NMR databases in achiral and chiral solvents, the complete stereochemistry of tetrafibricin (1) has been elucidated without degradation of the carbon framework. [structure--see text]     

Complete Carbonylation of fac-

The rate constant of ligand exchange on the complex fac-[(99)Tc(H(2)O)(3)(CO)(3)](+) was determined by means of (13)C, (17)O, and (99)Tc NMR spectroscopy under pressurized conditions in aqueous media. After keeping the sample under CO pressure for an extended period, the formation of [(99)Tc(CO)(6)](+) could unambiguously be detected in the (13)C and (99)Tc NMR spectra.     

Complete functionalisation of small and large diameter bromopolystyrene beads; applications for solid-supported reagents, scavengers and diversity-oriented synthesis

Bromopolystyrene beads with diameters of up to 600 microm have been derivatized completely, via bromine-magnesium exchange and interception with electrophiles, to yield high quality solid-supported reagents, scavengers and solid supports for use in diversity-oriented synthesis.     

Complete error potential

The complete error potential is a function of electronic and nuclear coordinates which has to be added to the physical potential in order to obtain the eigenfunctions of the molecular Hamiltonian in an a priori specified approximation. This potential is essential for the error theory, in particular it furnishes a simple justification of the Born-Oppenheimer approximation. It is given as a sum of the electronic error potential and that of the intramolecular forces, whose importance is discussed.Dedicated to Professor J. Koutecký on the occasion of his 65th birthday     

Complete NMR assignments of tubulosine

This article reports the structural elucidation of the Alangium alkaloid, tubulosine (1) on the basis of systematic 2D-NMR analyses (DEPT, COSY, TOCSY, NOESY, ROESY, HMQC and HMBC). The data obtained allowed the unambiguous assignment of all proton and carbon signals in 1 for the first time.     

Complete wetting of curved microscopic channels

We have measured the adsorption of argon films on arrays of microscopic nonlinear cusps and of semicircular channels. In the former case, we observe a distinct crossover from a planarlike to a geometry dependent growth behavior near liquid-vapor bulk coexistence, characterized by a growth exponent chi equal to -0.96+/-0.04 in very good agreement with the predictions of a recent scaling theory [C. Rascon and A. O. Parry, J. Chem. Phys. 112, 5175 (2000)]. The crossover location is also consistent with theory. Instead, on the concave channels we find a much steeper growth near saturation that may signal the formation of two menisci at both sides of the channel bottom.     

Complete maps of molecular-loop conformational spaces

This paper presents a numerical method to compute all possible conformations of distance-constrained molecular loops, i.e., loops where some interatomic distances are held fixed, while others can vary. The method is general (it can be applied to single or multiple intermingled loops of arbitrary topology) and complete (it isolates all solutions, even if they form positive-dimensional sets). Generality is achieved by reducing the problem to finding all embeddings of a set of points constrained by pairwise distances, which can be formulated as computing the roots of a system of Cayley-Menger determinants. Completeness is achieved by expressing these determinants in Bernstein form and using a numerical algorithm that exploits such form to bound all root locations at any desired precision. The method is readily parallelizable, and the current implementation can be run on single- or multiprocessor machines. Experiments are included that show the method's performance on rigid loops, mobile loops, and multiloop molecules. In all cases, complete maps including all possible conformations are obtained, thus allowing an exhaustive analysis and visualization of all pseudo-rotation paths between different conformations satisfying loop closure.     

Complete oxidation of ethanol over MnOx

MnO_x was synthesized through the oxidation of MnCO₃ and its catalytic activity in the complete oxidation of ethanol was determined. Analyses of the catalyst through in situ X-Ray Diffraction and in situ DRIFTS spectroscopy showed the presence of Mn₂O₃ (bixbyite) and γMnO_2. The catalytic activity of MnO_x depends on the mixtures of oxides and the treatment before reaction. This revised version was published online in June 2006 with corrections to the Cover Date.     

Complete multi-configuration self-consistent field theory

The two-configuration self-consistent field formalism previously presented in this Journal is extended and the CMC SCF LCAO MO (complete multi-configuration self-consistent field LCAO MO) technique is presented. The single Slater determinant for a 2n electron system is replaced by a combination of determinants built from two sets of MO's, one containingn orbitals; the second, ( —n) orbitals. All the possible double excitations from the (n) set to the ( —n) set are considered. The orbitals as well as the linear combination of determinants are simultaneously optimized making use of the self-consistent field technique.

---

Zusammenfassung Es wird die Methode des self-consistent field für eine Gesamtheit mehrerer Konfigurationen in der LCAO-Näherung entwickelt. Ein 2n-Elektronensystem wird nicht mehr durch eine einzige Slaterdeterminante, sondern durch eine Kombination von Determinanten beschrieben, die aus zwei Sätzen von Molekülfunktionen mitn bzw. ( —n) Orbitalen aufgebaut werden. Alle möglichen zweifachen Anregungen vom (n) zum ( —n) Satz werden berücksichtigt. Mit Hilfe der SCF-Teehnik werden sowohl die Orbitale als auch die Kombination der Determinanten gleichzeitig optimiert.

---

Résumé On expose la méthode du champ self-consistant pour un ensemble complet de plusieurs configurations, dans l'approximation LCAO-MO (CMC SCF LCAO MO). Le déterminant de Slater pour un système de 2n électrons est remplacé par une combinaison de déterminants construits a partir de deux ensembles d'orbitales moléculaires, l'un contenant (n) orbitales et l'autre (-n) orbitales. On considère toutes les doubles excitations possibles, de l'ensemble (n) à l'ensemble (-n). La technique du champ self-consistant permet d'optimiser simultanément les orbitales ainsi que les coefficients dans la combinaison linéaire de determinants. La méthode CMC SCF tient plainement compte de la corrélation associée à chaque paire d'électrons et fait intervenir toutes les interactions paire-paire. L'optimisation simultanée des orbitales des deux ensembles (n) et (-n) garantit une convergence rapide.

     

苯醚菊酯气质联用全分析研究

采用气质联用分析外标定量法,测定了苯醚菊酯的顺、反式异构体及其总含量;采用制备衍生物,气质联用分析法,测定了苯醚菊酯4个光学异构体和主要副反应产物的含量,确定了它们的化学结构式,实现了苯醚菊酯定性、定量全分析.     

Complete nanofibrillation of cellulose prepared by phosphorylation

In this work, we prepared phosphorylated pulp with a phosphorous content of 1.23 mmol/g by adding an aqueous solution of NH₄H₂PO₄ and urea to softwood pulp sheets followed by drying and curing with hot air and obtained cellulose nanofibers (CNFs) with a uniform width of 3–4 nm in approximately 100% gravimetric yield by high-pressure homogenization of the phosphorylated pulp slurry. After phosphorylation, no significant decrease in the pulp recovery ratio was observed, and the viscosity-average degree of polymerization of phosphorylated pulp was almost equal to that of the original pulp. In addition, the crystal structure and crystallinity index were almost unchanged during phosphorylation. The obtained phosphorylated CNF dispersion was highly transparent, and the maximum total light transmittance was nearly 100% when the CNF content was 0.2 wt%. The maximum viscosity of the CNF dispersions was nearly 10–100 times greater than that of conventional thickeners. Furthermore, we found that not only insufficient but also excessive phosphorylation negatively affected the gravimetric yield, transparency and viscosity.     

Complete valence double photoionization of SF6

Single photon double ionization of SF(6) has been investigated at the photon energies 38.71, 40.814, and 48.372 eV by using a recently developed time-of-flight photoelectron-photoelectron coincidence spectroscopy technique which gives complete two-dimensional e(-)-e(-) spectra. The first complete single photon double ionization electron spectrum of SF(6) up to a binding energy of approximately 48 eV is presented and accurately interpreted with the aid of Green's function ADC(2) calculations. Spectra which reflect either mainly direct or mainly indirect (via interatomic coulombic decay of F 2s holes) double ionization of SF(6) are extracted from the coincidence map and discussed. A previous, very low value for the onset of double ionization of SF(6) is found to energetically coincide with a peak structure related to secondary inelastic scattering events.