Synthesis and crystal structure of 10a‐oxo‐1‐phenylimino‐ 10‐propyl‐3,4,10,10a‐tetrahydro‐1H‐ 2‐thia‐4a,10‐diaza‐10aλ5‐ phospha‐phenanthren‐9‐one

The title novel fused tricyclic phosphoroheterocycle, C₁₉H₂₀N₃O₂PS, was synthesized in an excellent yield of 88.5% via the reac‐ tion of 1‐(2‐bromoethyl)‐2,3‐dihydro‐3‐propyl‐1,3,2‐benzodiazaphosphorin‐4(1H)‐one 2‐oxide with phenyl isothiocyanate, which contains the proximate imino and phosphoryl groups in the fused heterocycle. The crystallographic data analysis reveals that the title compound crystallizes into triclinic space group P with unit cell parameters: a = 9.159(3) Å, b = 10.463(4) Å, c = 10.698(4) Å, α = 88.090(6)°, β = 86.921(6)°, γ = 70.528(6)°, V = 965.0(6) ų for Z = 2 and there is a fused three‐ring in the molecule. The structure has been solved by direct methods and refined to R = 0.0424 for 2451 observed reflections with I >2 σ(I). The proximate imino and phosphoryl groups are not coplanar because both are jointly located in the fused heterocycle, thus having ring tension and this then destroys the conjugation between the CN and the PO moieties. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:671–676, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20169     

Particle‐in‐a‐Frame Nanostructures with Interior Nanogaps

Designing plasmonic hollow colloids with small interior nanogaps would allow structural properties to be exploited that are normally linked to an ensemble of particles but within a single nanoparticle. Now, a synthetic approach for constructing a new class of frame nanostructures is presented. Fine control over the galvanic replacement reaction of Ag nanoprisms with Au precursors gave unprecedented Au particle‐in‐a‐frame nanostructures with well‐defined sub‐2 nm interior nanogaps. The prepared nanostructures exhibited superior performance in applications, such as plasmonic sensing and surface‐enhanced Raman scattering, over their solid nanostructure and nanoframe counterparts. This highlights the benefit of their interior hot spots, which can highly promote and maximize the electric field confinement within a single nanostructure.     

Indium Trichloride Catalyzed Diels–Alder Reaction: Synthesis of Novel 5‐Butyl‐11a‐aryl‐4a,5,11,11a‐tetrahydro‐11bH‐indolo[3,2‐c]quinoline‐1,4‐dione

Hetero Diels–Alder reaction of 3‐butyliminomethyl‐2‐aryl‐1H‐indoles (Schiff's base) 1 with p‐benzoquinone 2 affords six novel 5‐butyl‐11a‐aryl‐4a,5,11,11a‐tetrahydro‐11bH‐indolo[3,2‐c]quinoline‐1,4‐diones 3 in good yields. All the reactions proceeded with complete diastereoselectivity giving only one product in each case, which was characterized on the basis of its elemental analyses and spectral data (IR, ¹H NMR, and Mass).     

9‐Phenyl‐3,4,4a,9a‐tetrahydrotri­ptycene and 9‐phenyl‐1,2,3,4,4a,9a‐hexa­hydro­triptycene

The structure of 9‐phenyl‐3,4,4a,9a‐tetra­hydro­triptycene, C₂₆H₂₂, (I), exhibits regiochemistry consistent with a stepwise mechanism for its formation from photo­cyclo­addition of 1,3‐cyclo­hexa­diene and 9‐phenyl­anthracene. Bond distances involving the bridgehead C atoms are similar in (I) and the hydrogenated derivative, 9‐phenyl‐1,2,3,4,4a,9a‐hexa­hydro­triptycene, C₂₆H₂₄, (II), with bonds to the quaternary‐C atoms exhibiting significant elongation [1.581 (2) Å in (I) and 1.585 (2) Å in (II)]. The molecular geometry precludes significant σ–π overlap between the phenyl groups and the interannular bonds in both compounds, indicating that the origin of the bond lengthening is steric in nature.     

1,4‐Methano‐11a‐methyl‐4,4a,11,11a‐tetrahydro‐1H‐benzo­[b]­fluoren‐11‐one

The title compound, C₁₉H₁₆O, crystallizes with two mol­ecules of opposite chirality in the asymmetric unit. In both mol­ecules, the naphthalene and cyclo­pentanone moieties are individually planar. The two cyclo­pentane rings adopt envelope conformations, while the cyclo­hexane ring adopts a boat conformation.     

[1a(1aα,5β,9aα)]‐1,1a,4,5,7,8,9,9a‐Octahydro‐3‐hydroxy‐1,1,2,5‐tetramethyl‐7‐methylene‐6H‐cyclopropa[3,4]cyclo­hept[1,2‐e]inden‐6‐one

Interest in the title structure, C₂₀H₂₄O₂, lies in the novel cis ring junction between the three‐ and seven‐membered rings. This stereochemical arrangement causes the methylene moiety and the cycloheptane ring to be twisted out of the plane of the aromatic ring. The cyclopropane ring is also twisted out of the plane of the aromatic system. The molecules are linked by an O—H?O hydrogen bond [O?O 2.741 (3) Å].     

Quantized Double‐Layer Charging of Iron Oxide Nanoparticles on a‐Si:H Controlled by Charged Defects in a‐Si:H

Sequential single‐electron charging of iron oxide nanoparticles encapsulated in oleic acid/oleyl amine envelope and deposited by the Langmuir‐Blodgett technique onto Pt electrode covered with undoped hydrogenated amorphous silicon film (a‐Si:H) is reported. Quantized double‐layer charging of nanoparticles is detected by cyclic voltammetry as current peaks and the charging effect can be switched on/off by the excess of negative/positive charged defect states in the a‐Si:H layer. The particular charge states in a‐Si:H are created by the simultaneous application of a suitable bias voltage and illumination before the measurement.     

(4aR,8aS,9aR,10aS)‐8a,9a‐Difluoro‐1,4,4a,5,8,8a,9,9a,10,10a‐decahydroanthracene‐4a,10a‐diol hemihydrate

The title compound, C₁₄H₁₈F₂O₂·0.5H₂O, a hemihydrate of a C_s‐symmetric unsaturated difluorodiol, crystallizes in the centrosymmetric space group P2/m (Z = 4). The asymmetric unit contains two crystallographically independent difluorodiol half‐molecules, occupying the mirror planes at (x, 0, z) and (x, , z), and half a molecule of water, lying on the twofold axis at (0, y, 0). Four difluorodiol molecules self‐assemble around each solvent water molecule via O—H...O hydrogen bonds in a near tetrahedral symmetry to generate a cylindrical column‐like architecture.     

11‐Methyl‐12a‐phenyl‐9a,12a‐dihydrophenanthro[9′,10′:5,6][1,4]dioxino[2,3‐d]oxazole and 9a‐(10‐hydroxyphenanthren‐9‐yl)‐11,12a‐diphenyl‐9a,12a‐dihydrophenanthro[9′,10′:5,6][1,4]dioxino[2,3‐d]oxazole

In the title compounds, C₂₄H₁₇NO₃, (I), and C₄₃H₂₇NO₅, (II), the dioxine ring is not planar and tends toward a boat conformation. The oxazoline ring adopts a twisted conformation in mol­ecule (I) but is essentially planar in mol­ecule (II). The configuration of the dioxine–oxazoline system is determined by the sp³ state of the two shared atoms. The phenanthrene moiety is nearly coplanar with the dioxine ring, while the phenyl ring is perpendicular to the attached oxazole ring. The triclinic unit cell of (II) contains two crystallographically independent mol­ecules related by a pseudo‐inversion centre.     

Synthesis of 7a‐aryl‐5‐t‐butyl‐3‐methyleneoctahydrobenzofuran possessing partial skelotons of some santonin analogue and furanolignans by intramolecular radical cyclisation reaction

Bicyclic octahydrobenzofuran derivatives ( 1c‐6c ) possessing the partial skeletons of santonin ( 7 ), 11,13‐dehydroisohyposantonin ( 8 ), dihydrosesamin ( 9 ) and lariciresinol ( 10 ) have been synthesised by intramolecular radical cyclisation in good yield via the precursors viz., the trans diaxial bromopropynyl ethers ( 1b‐6b ) obtained in highly regio/stereoselective manner.     

2,3,3a,4,5a,6,7,8‐Octa­hydro‐5a‐methyl‐6,9‐methano‐1H,9H‐5‐oxa‐4‐aza­cyclo­penta­[c]­indene

The regio‐ and stereochemistry of the title compound, C₁₂H₁₅NO, has been established by X‐ray analysis. The molecular dimensions are normal.     

Detecting Single‐Molecule Dynamics on Lipid Membranes with Quenchers‐in‐a‐Liposome FRET

Tracking membrane‐interacting molecules and visualizing their conformational dynamics are key to understanding their functions. It is, however, challenging to accurately probe the positions of a molecule relative to a membrane. Herein, a single‐molecule method, termed LipoFRET, is reported to assess interplay between molecules and liposomes. It takes advantage of FRET between a single fluorophore attached to a biomolecule and many quenchers in a liposome. This method was used to characterize interactions between α‐synuclein (α‐syn) and membranes. These results revealed that the N‐terminus of α‐syn inserts into the membrane and spontaneously transitions between different depths. In contrast, the C‐terminal tail of α‐syn is regulated by calcium ions and floats in solution in two conformations. LipoFRET is a powerful tool to investigate membrane‐interacting biomolecules with sub‐nanometer precision at the single‐molecule level.     

Syntheses of 2,3‐dicyano‐5a,8a‐dihydro‐5a‐hydroxycyclopentano[1′,2′:4,5]pyrrolo[2,3‐b]pyrazines and 2,3‐dicyanocyclohexano[1′,2′:4,5]pyrrolo‐[2,3‐b]pyrazines

Previously synthesized 2‐(3′‐chloro‐5′,6′‐dicyanopyrazin‐2′‐yl)cyclopentan‐1‐one 1 , obtained from the reaction of 2,3‐dichloro‐5,6‐dicyanopyrazine with 1‐pyrrolidino‐1‐cyclopentene, was further reacted with primary alkylamines to give mixtures of diastereomer of 5‐alkyl‐2,3‐dicyano‐5a,8a‐dihy‐dro‐5a‐hydroxycyclopentano[1′,2′:4,5]pyrrolo[2,3‐b]pyrazines 3a‐h in high yield. The reaction of 2‐alkylamino‐3‐chloro‐5,6‐dicyanopyrazine with 1‐pyrrolidino‐1‐cyclohexene gave 5‐alkyl‐2,3‐dicyanocyclopentano[1′,2′:4,5]pyrrolo[2,3‐b]pyrazines 5a‐b together with 5‐alkylamino‐2,3‐dicyano‐6‐pyrrolidinopyrazines 6a‐b . The products prepared are all of interest as potential pesticides and new fluorescent chromophores.     

Comparative study of microstructure and tribological behavior of TiC/a‐C:H and a‐C:H coatings in a sand‐dust environment

TiC/a‐C:H and a‐C:H nanocomposite coatings were prepared on AISI 440C steel substrates using magnetron sputtering process. A comparative study was made on their composition and microstructure by Raman spectroscopy and high‐resolution transmission electron microscopy (HRTEM). The tribological properties of two types of carbon‐based coatings were investigated by pin‐on‐disc tribometer under the sand‐dust conditions concerning the influence of applied load, amount of sand and sand particle sizes. The results show that these carbon‐based coatings exhibited high tribological performance with low friction coefficient and wear rate under the sand‐dust environments. However, the TiC/a‐C:H coatings exhibit relatively higher fluctuant friction coefficient as well as higher wear rate in comparison with the a‐C:H coatings under sand‐dust environments. The formation of nanocrystalline hard TiC phase distributed in amorphous carbon matrix decreased the residual stress but significantly increased the hardness and Young's modulus of TiC/a‐C:H coatings, and consequently caused a relatively higher abrasive and fatigue wear loss under the sand‐dust conditions. Copyright © 2010 John Wiley & Sons, Ltd.     

3,3′‐Dimesityl‐7‐methyl‐9a‐phenyl‐4,4′,5,5′,6,8,9,9a‐octa­hydro‐7H‐1,2,4‐oxa­diazo­lo­[4,5‐d][1,4]­diazepine‐8‐spiro‐5′‐isoxazole

Condensation of mesito­nitrile oxide with 1,7‐di­methyl‐5‐phenyl‐2,3‐di­hydro‐1H‐1,4‐diazepine leads to two cycloadducts (I) and (II). The structure and stereochemistry of the dicyclo­adduct (II) was established by X‐ray crystallographic analysis.     

Complete assignment of the 1H and 13C NMR spectra of four 2‐substituted 4a,8a‐cis‐endo‐5,8‐methano‐4a,5,8,8a‐tetrahydronaphthalene‐1,4‐diones

The complete assignment of the ¹H and ¹³C NMR spectra of the title enediones, bearing as substituents N‐aziridinyl (a novel compound), methoxy, chloro and methylsulfanyl, is reported. Copyright © 2002 John Wiley & Sons, Ltd.     

Two diastereomers of 9‐(2,6‐di­chloro­phenyl)‐4a‐hydroxy‐3,3,6,6‐tetra­methyl‐1,2,3,4,4a,5,6,7,8,9a‐deca­hydro­xanthene‐1,8‐dione in the same crystal

The reaction of dimedone with 2,6‐di­chloro­benz­aldehyde leads to the title compound, C₂₃H₂₆Cl₂O₄. In principle, the reaction could yield eight different stereoisomers. We have found four of them in the same crystal as two enantiomeric pairs of diastereomers, which means that the asymmetric unit is built up of two different diastereomers. Two of the three chiral centres display the same configuration, while the third is different in the two mol­ecules in the asymmetric unit. The packing of the mol­ecules is stabilized by hydrogen bonds between the hydroxy group and the carbonyl group attached to the cyclo­hexene ring, forming chains in which the different diastereomers alternate.