The synthesis of benzofuroquinolines. I. Some benzofuro[2,3-b]quinoline and benzofuro[3,2-c]quinoline derivatives

Benzofuro[2,3-b]quinoline ( Ia ) and its 11-methyl derivative ( Ib ) were synthesized by demethylcyclization of 3-(o-methoxyphenyl)-1,2-dihydroquinolin-2-ones (VIa,b). Benzofuro[2,3-b]quinoline-11-carboxylic acid (Id) was synthesized by chlorination followed by the action of potassium hydroxide of a lactone (IX) prepared by demethyl-cyclization of 3-(o-methoxyphenyl)-2-oxo-1,2-dihydroquinoline-4-carboxylic acid (VIII). Isomeric benzofuro[3,2-c]quinoline (Ha) and its 6-methyl derivative (IIb) were synthesized by demethyl-cyclization of 3-(o-methoxyphenyl)-1,4-dihydroquinolin-4-ones (XIa,b). Both the methyl derivatives (Ib and IIb) were converted to the carboxylic acids (Id and IId) through condensation with benzaldehyde followed by oxidation. The benzofuroquinolines (Ia,b,d and IIa,b) thus obtained were oxidized to the corresponding N-oxides (IIIa,b,d and IVa,b).     

温度对液态水结构的影响：中子及X射线散射研究

采用中子散射和X射线散射研究了液态水在298～373 K温度范围内的结构,通过偏径向分布函数(PDF)、配位数分布(CN)、角分布(ADF)及空间密度分布(SDF)等讨论了温度对液态水结构的影响。整体来看,液态水具有"不规则四面体"氢键网络的短程有序结构,该有序度可延续到第三水合层。液态水分子的第一水合层中,围绕中心水分子约有4.8个水分子,然而其中仅有约3.3个水分子与中心水分子通过氢键相键合,约1/3进入到第一水合层的水分子并未与中心水分子直接键合,也正是这些间隙水分子的存在加剧了液态水结构的复杂性。温度对液态水的有序度存在一定的影响,在298～373 K的有限温度变化范围内,温度对液态水中氢键的键长、键角分布及第一水合层SDF的影响不大。从298K升温到373K,O(W)-O(W)距离仅增加0.03?,氢键数目也仅有微小减少,温度对第二和第三水合层的影响则要显著很多。     

Diffusivities of tris(2,2'-bipyridyl)ruthenium inside silica-nanochannels modified with alkylsilanes.

The apparent diffusion coefficients of tris(2,2'-bipyridyl)ruthenium ([Ru(bpy(3))](2+)) are estimated in silica-nanochannels which are assembled inside columnar alumina pores in an anodic alumina membrane, and are modified with alkylsilanes such as trimethylchlorosilane (C1), butyldimethylchlorosilane (C4), and dodecyldimethylchlorosilane (C12). The estimation is performed by observing the lag-time, which is defined as the time required for [Ru(bpy)(3)](2+) to diffuse through alkylsilane-modified silica-nanochannels in the alumina membrane. When ethanol is used as a solvent, the apparent diffusion coefficients of [Ru(bpy)(3)](2+) are estimated as 2.1 x 10(-10) and 3.2 x 10(-10) cm(2) s(-1) in the C1- and C4-modified silica-nanochannels, respectively. These values are about 10(4) times smaller than that obtained in bulk ethanol. Based on the experimental results on the solvent dependency of the lag-time, the hydrogen-bonding interaction between ethanol molecules is considered to be stronger in the C1- and C4-modified silica-nanochannels than in bulk ethanol, and the hydrogen-bonding interaction plays a critical role for the slow diffusivity in those nanochannels. In contrast, the apparent diffusion coefficient in the C12-modified silica-nanochannel is at least two orders of magnitude larger than those in the C1- and C4-modified silica-nanochannels. This relatively fast diffusion is most likely explained by the presence of a long alkyl chain of C12, which reduces a hindrance effect that is originates in the hydrogen-bonding interaction.     

Convergent and stereoselective synthesis of vitamin D3 via 3,5-cyclovitamins D3

A convergent and stereoselective synthesis of vitamin D₃ was achieved via 3,5-cyclovitamins D₃ (20) which were prepared from the chiral aldehyde (2) and the vinyl bromide (12) derived from Grundmann's ketone.     

Revisit to the intrinsic viscosity-molecular weight relationship of ionic polymers. 7. Examination of the Pals-Hermans dilution method with reference to the viscosity behavior of dilute aqueous dispersion of ionic polymer latex

The isoionic dilution method, which was proposed by Pals and Hermans, for linear ionic polymer solutions, was examined for the viscosity behavior of dilute aqueous dispersion of ionic latex [particle diameter, (0.120 ± 0.003) × 10^–6 m; surface charge density, 1.6 × 10^–6 C/cm²] in the presence of sodium chloride (5 × 10^–5 to 5 × 10^–4 M). Linear relations were obtained between the reduced viscosity and the latex concentration, when a parameter m, which appeared in the effective ionic strength introduced by Pals and Hermans, was chosen to be about 0.1. This finding on the latex system does not support that, at the salt and polymer concentrations employed, the dimension of linear macroions varies with changing effective ionic strength and it is kept constant along the isoionic dilution line. Brief discussion on the m value is presented. ©1995 John Wiley & Sons, Inc.     

Development and validation of a liquid chromatographic method for the analysis of positron emission tomography radiopharmaceuticals with Ru(bpy)(3)(2+)-KMnO(4) chemiluminescence detection.

A sensitive, selective and rapid high-performance liquid chromatographic (HPLC) method with chemiluminescence (CL) detection was developed and validated for the analysis of positron emission tomography (PET) radiopharmaceuticals. This method is based on the CL reaction of PET compounds with tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)] and acidic potassium permanganate [KMnO(4)]. After optimization of the reaction conditions, 12 of the 14 PET compounds investigated could be successfully detected and showed good performance in terms of sensitivity, linearity and reproducibility. In particular, for compounds with a tertiary amine functional group, the limits of detection were ppb levels for a 20 microL injection volume. Finally, this method was used to determine PET compounds for calculating of specific radioactivity in pharmaceutical samples.     

Selective determination of tryptophan-containing peptides through precolumn derivatization and liquid chromatography using intramolecular fluorescence resonance energy transfer detection.

A selective and sensitive fluorometric determination method for native fluorescent peptides has been developed. This method is based on intramolecular fluorescence resonance energy transfer (FRET) detection in a liquid chromatography (LC) system following precolumn derivatization of the amino groups of tryptophan (Trp)-containing peptides. In this detection process, we monitored the FRET from the native fluorescent Trp moieties (donor) to the derivatized fluorophore (acceptor). From a screening study involving 10 fluorescent reagents, we found that o-phthalaldehyde (OPA) generated FRET most effectively. The OPA derivatives of the native fluorescent peptides emitted OPA fluorescence (445 nm) through an intramolecular FRET process when they were excited at the excitation maximum wavelength of the Trp-containing peptides (280 nm). The generation of FRET was confirmed through comparison with the analysis of a non-fluorescent peptide (C-reactive protein fragment (77 - 82)) performed using LC and a three-dimensional fluorescence detection system. We were able to separate the OPA derivatives of the Trp-containing peptides when performing LC on a reversed-phase column. The detection limits (signal-to-noise ratio = 3) for the Trp-containing peptides, at a 20-microL injection volume, were 41 - 180 fmol. The sensitivity of the intramolecular FRET-forming derivatization method is higher than that of the system that takes advantage of the conventional detection of OPA derivatives. Moreover, native non-fluorescent amines and peptides in the sample monitored at FRET detection are weaker than those of conventional fluorescence detection.     

Hyperfine interaction of13O and23Mg implanted in Pt

The spin relaxation timeT ₁ for short-lived beta emitters¹³O and²³Mg implanted in Pt have been measured for the first time;T ₁T¹³O) = 2.90 ±0.65 Ks andT ₁ T(²³Mg) = 1665 ±140 Ks. The Knight shift for¹³O in Pt was measured at 300 K to beK(¹³O) = +(4.23 ±0.14) × 10^–3. In the case of¹³O, the Knight shift is unusually large and the relaxation time is unusually fast compared with other interstitial impurities in Pt. A KKR band-structure calculation reproduces the present large Knight shift fairly well.     

Linear and A2+B3‐type hyperbranched polyesters comprising phenylbenzothiazole unit: Preparation,liquid crystalline,and optical properties

Novel liquid crystalline (LC) hyperbranched (HB) polyesters comprising phenylbenzothiazole (PBT) unit as mesogen in the interiors were prepared at various feed mole ratios (A₂/B₃) by solution polycondensation of a dioxydiundecanol derivative of PBT (A₂ monomer) with trimesic acid trimethyl ester (B₃ monomer) via A₂+B₃ approach and their LC and optical properties were investigated. Analogous linear polyesters containing the PBT unit in the main chains were also prepared by the solution polycondensation of A₂ monomer with aromatic or aliphatic dimethyl esters. FTIR and ¹H‐NMR spectroscopies indicated that the HB polyesters are produced without gelation during the polycondensation and have degree of branching (DB) of 7–46%. The structures of HB polymers changed depending on the feed mole ratios and the polymer prepared in the mole ratio of A₂/B₃ = 3/2 had the highest inherent viscosity and DB. Acetylation of terminal OH group‐having HB polyesters prepared in excess mole ratios of A₂/B₃ afforded ones bearing acetoxy groups in the terminals. DSC measurements, polarizing microscope observations of textures, and X‐ray analyses suggested that only the terminal OH group‐having HB polymer prepared in the mole ratio of A₂/B₃ = 3/1 form smectic C phase. In the linear polymers, the polymers derived by using the aromatic dimethyl esters had no LC melt, but those from the aliphatic dimethyl esters formed LC smectic C phase. The acetoxy group‐bearing HB polymers showed more stable smectic A or C phase than those with the OH terminals. Solution UV‐vis and photoluminescent (PL) spectra indicated that the linear and the HB polymers have analogous optical properties and display maximum absorbances and blue‐light emission on the basis of the PBT unit, where the Stokes shifts were observed because of intermolecular aggregation effects, but there is a large difference between the optical behaviors of the linear and the HB polymers in film, whose E_g values of the linear polymers decreased and those of the HB polymers vice versa. Quantum efficiencies (Φ) had a tendency of increase in the linear polymers and the HB polymers forming LC phases. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6688–6702, 2008     

Stress relaxation under large step equibiaxial elongation for low‐density polyethylene

The stress relaxation under large step equibiaxial elongation for low‐density polyethylene with long‐chain branches revealed that the time‐strain separability holds in relaxation modulus G_B(t, ε_B), and damping function h_B(ε_B) exhibits weaker equibiaxial elongational strain ε_B dependence than that predicted by the Doi–Edwards theory without the independent alignment approximation. Dependencies of damping function h(γ) for step shear deformation and h_B(ε_B) on stretch ratio α of polymer contour length and orientation of a polymer chain in direction of the maximum orientation were evaluated, and it was found that the α dependencies of h(γ) and h_B(ε_B) are different, whereas dependencies of h(γ) and h_B(ε_B) on the orientation coincide fairly well. These results indicate that the damping is dominated by the chain orientation rather than α. This implies that withdrawal of long‐chain branches into tube of a backbone chain occurs when the orientation of the long‐chain branches is large and friction force against the branch point withdrawal is small. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1275–1284, 2009