نتایج جستجو برای: f 18
تعداد نتایج: 633014 فیلتر نتایج به سال:
In the title compound, C24H17NO2, the carbonyl O atom of the benzoyl group is cis with respect to the furanyl O atom, and the associated O-C-C-O torsion angle is 4.62 (19)°. The puckering of the dihydro-furan ring is close to twisted ((4) T 5), with parameters Q = 0.1856 (16) Å and φ = 313.5 (5)°. Mol-ecules are inter-connected via a C-H⋯N and a C-H⋯O hydrogen bond, leading to layers parallel t...
Hydrogenases are enzymes of great biotechnological relevance because they catalyse the interconversion of H2, water (protons) and electricity using non-precious metal catalytic active sites. Electrochemical studies into the reactivity of NiFe membrane-bound hydrogenases (MBH) have provided a particularly detailed insight into the reactivity and mechanism of this group of enzymes. Significantly,...
It is a great pleasure to be able to introduce this Themed series on organo-fluorine chemistry in the Beilstein Journal of Organic Chemistry. The introduction of fluorine into organic molecules is widely practiced particularly when tuning the properties of molecules for specialist functions. Of particular prominence is the role fluorine substitution finds in pharmaceutical development [1], and ...
OBJECTIVE this study aimed to perform a comprehensive validation of the 16-item and 7-item Falls Efficacy Scale International (FES-I) by investigating the overall structure and measurement properties, convergent and predictive validity and responsiveness to change. METHOD five hundred community-dwelling older people (70-90 years) were assessed on the FES-I in conjunction with demographic, phy...
Fluorinated, contorted hexabenzocoronenes (HBCs) have been synthesized in a facile manner via Suzuki-Miyaura coupling of fluorinated phenyl boronic acids followed by photocyclization and Scholl cyclization. In addition to the molecular conformation observed in previous HBC derivatives, close-contact fluorine-fluorine intramolecular interactions result in a metastable conformation not previously...
Liquid-crystal phases with both solid and liquid characteristics are unique, since they exhibit chirality on both molecular and mesoscopic levels under special circumstances. We have studied binary composites formed by mixing of a chiral dimer (B-Ch), in which a bent core is covalently linked to a promesogenic cholesterol unit through a flexible spacer, and an achiral bent-core mesogen having t...
The information accessible from a muon-spin relaxation experiment can be limited due to a lack of knowledge of the precise muon stopping site. We demonstrate here the possibility of localizing a spin polarized muon in a known stopping state in a molecular material containing fluorine. The muon-spin precession that results from the entangled nature of the muon spin and surrounding nuclear spins ...
The effect of variously fluorine-substituted β-methyl-β-nitrostyrenes on their antimicrobial activity was investigated. Their efficacy was determined by minimum inhibition concentration (MIC) in cultures of Gram positive and Gram negative bacteria and a fungus. Highest activity against the Gram negative bacterium, E.coli, was achieved with 4-fluorine-aryl substituted β-methyl-β-nitrostyrenes, w...
The large discrepancies between the calculated and observed structures for BrF(4)(+) and IF(4)(+) (Christe, K. O.; Zhang, X.; Sheehy, J. A.; Bau, R. J. Am. Chem. Soc. 2001, 123, 6338) prompted a redetermination of the crystal structures of BrF(4)(+)Sb(2)F(11)(-) (monoclinic, P2(1)/c, a = 5.2289(6) A, b = 14.510(2) A, c = 14.194(2) A, beta = 90.280(1) degrees, Z = 4) and IF(4)(+)SbF(6)(-) (ortho...
The enantio- and diastereoselective Michael addition of a δ-valerolactone-derived pronucleophile to a substituted furanyl nitroolefin catalysed by a bifunctional cinchonine-derived thiourea has been used as the key stereocontrolling step in a new synthetic strategy to the heavily functionalised piperidine core of keramaphidin B.
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