Synthesis and evaluation of 6-nitro-7-(1-piperazino)quinazolines: dual-acting compounds with inhibitory activities toward both tumor necrosis factor-alpha (TNF-alpha) production and T cell proliferation

We investigated the chemical modifications of the nitroquinazoline derivative (1) through the replacement of the NH group at the C(4)-position with several N-alkyl groups to increase the lipophilicity at the C(4)-position. Among them, we found that the N-methyl analogue (5a) showed a 2-fold loss in the inhibitory activity toward tumor necrosis factor-alpha (TNF-alpha) production in vitro as compared with the NH analogue (1); however, 5a exhibited an oral inhibitory activity on TNF-alpha production with an ED50 value of 26 mg/kg, whereas 1 did not. Moreover, the oral bioavailability of 5a was higher than that of 1 (1, F=1%; 5a, F=21%), and the calculated ClogP value for 5a was higher than that for 1. These results suggest that the improved lipophilicity of 5a compared with that of 1 reflects its greater inhibitory activity on TNF-alpha production in vivo as well as oral bioavailability.     

Systematic study on synthesis and structural, electrical transport and magnetic properties of Pb-substituted Bi-Ca-Co-O misfit-layer cobaltites

Single-phases of Pb-substituted Bi-Ca-Co-O misfit-layer cobaltites with various Pb concentrations have been synthesized and the Pb-substitution effects on the structural, electrical and magnetic properties have been systematically investigated. Powder X-ray diffraction analysis showed that the single-phases of Bi_1.8−x/2Pb_xCa₂Co₂O_z were obtained up to x=0.6-0.7 under the optimized synthesis conditions. The lattice parameters of Bi_1.8−x/2Pb_xCa₂Co₂O_z continuously changed with increasing Pb concentration. The electron diffraction analysis suggested that the structure consisted of two different sublattices with a rock salt structure (RS) and a hexagonal CdI₂ structure (H), respectively, without modulation. In combined with the chemical composition analysis, the chemical formulas of the x=0 and x=0.6 samples were determined approximately as [Bi_1.74Co_0.31Ca_2.01O₄]^RS[CoO₂]_1.69 and [Bi_1.47Pb_0.38Co_0.29Ca_1.98O₄]^RS[CoO₂]_1.71, respectively. The electrical resistivity became more metallic with increasing the Pb concentration up to x=0.6. Moreover, the Pb-substitution simultaneously increased the antiferromagnetic Weiss temperatures and decreased the effective magnetic moments of the Co ions.     

Efficient [3,3]-sigmatropic rearrangement accelerated by a trifluoroacetyl group: synthesis of benzofurans under mild conditions

The [3,3]-sigmatropic rearrangement took place smoothly during the course of trifluoroacetylation of O-phenyloxime at below room temperature to give the dihydrobenzofuran or benzofuran as a result of concomitant cyclization.     

Direct Transformation of Molecular Dinitrogen into Ammonia Catalyzed by Cobalt Dinitrogen Complexes Bearing Anionic PNP Pincer Ligands

The direct formation of ammonia from molecular dinitrogen under mild reaction conditions was achieved by using new cobalt dinitrogen complexes bearing an anionic PNP‐type pincer ligand. Up to 15.9 equivalents of ammonia were produced based on the amount of catalyst together with 1.0 equivalent of hydrazine (17.9 equiv of fixed nitrogen atoms).     

Raman spectroscopy of SWNTs produced by a XeCl excimer laser ablation at high temperatures

Synthesis of single-wall carbon nanotubes (SWNTs) was carried out by an ablation method using a XeCl excimer laser. It was irradiated onto a graphite target containing Co and Ni at the temperatures of 1073, 1173, 1273, 1373, 1473, 1523 and 1623 K under the atmosphere (0.1 MPa) of Ar gas with the flow rate of 12 ml/min. The measurement by a scanning/transmission electron microscope and Raman spectroscopy found the formation of SWNTs with the diameter of about 1.3 nm and the length of about 2 μm in ablated carbonaceous soot. The ratio of peak intensity of 1590 cm⁻¹ (G band) to that of 1335 cm⁻¹ (D band) in the high frequency Raman spectra increased with increasing the ambient temperature. The radial breathing mode (RBM) in the low frequency Raman spectra shows that the mean diameter of SWNTs increased with increasing the ambient temperature.     

Investigation into pH-responsive self-assembled monolayers of acylated anthranilate-terminated alkanethiol on a gold surface

This article describes the preparation of pH-responsive self-assembled monolayers (SAMs) of acylated anthranilate-terminated alkanethiol. These monolayers are formed by chemisorption of the alkanethiol molecules onto a gold surface, resulting in different wetting properties of the surfaces depending upon the pH. By using various characterization techniques (e.g., infrared spectroscopy, cyclic voltammetry, contact angle measurements, and surface energy analysis), we have found that the changes in the wetting properties originate from the different surface structures of the monolayers in different pH environments. From surface energy analysis, we found that the disperse components of the surface energy on such SAMs predominate after treatment with pH 1 water, whereas the polar components of the surface energy on such SAMs predominate after treatment with pH 13 water. It is greatly anticipated that this line of research will provide new insight into the mechanism behind pH-responsive properties, facilitating the design and synthesis of new surface-active molecules for the fabrication of pH-responsive functional surfaces.     

Nitrosation of Phenolic Substrates under Mildly Basic Conditions: Selective Preparation of p-Quinone Monooximes and Their Antiviral Activities

Nitrosation of 3-methoxyphenol and 1-naphthol were examined under both acidic (NaNO(2)-EtCO(2)H-H(2)O) and basic (i-AmNO(2)-K(2)CO(3)-DMF) conditions. Acidic nitrosations afforded ortho-directed products, whereas para-directed nitrosations were observed under basic conditions to yield p-quinone monooximes. The basic para-directed nitrosation was further examined using 15 phenols, two naphthols, and four phenolic heterocyclics. A one-pot operation of the basic nitrosation followed by methylation with dimethyl sulfate gave the corresponding methyl ethers in high yield. Two p-quinone monooximes derived from 3-methoxyphenol and 8-hydroxyquinoline showed a moderate activity against HSV-1, and the latter oxime was also effective against HSV-2. On the other hand, p-quinone monooximes derived from methyl salicylate, 1-naphthol, 7-hydroxy-2-methylbenzo[b]furan, and 8-hydroxycoumarin showed the comparable activity to that of DDI against HIV-1.     

Rates of electronic excitation hopping in anisotropic ionic crystals of [Ru(2,2'-bipyridine)3]X2 (X = ClO4-, PF6-, SbF6-); Monte Carlo simulation of single- and multi-exponential emission decays

Emission decays of triplet metal-to-ligand charge transfer states in anisotropic crystals of [Ru(1 - x)Os(x)(bpy)(3)]X(2) (bpy = 2,2'-bipyridine, X = PF(6)-, ClO(4)-, SbF(6)-, and 0.115 > x > 0.001) at approximately 300 K were measured by means of time-correlated single-photon counting. Rates of excitation hopping calculated on the basis of an interaction between transition dipoles of a donor cation and an acceptor cation are insufficient to simulate the single-exponential decays (x = 0.0099) and the multiexponential decays (x = 0.060 and 0.115) of the PF(6)- salt crystals. A limiting rate of excitation hopping to an imaginary cation at the van der Waals distance via a super-exchange interaction between d orbitals through the bpy ligands was determined to be 0.83 x 10(10) s(-1) on average by means of a step-by-step Monte Carlo simulation, assuming an distance-attenuation factor, beta, of the exchange interaction of 10 nm-1. The total rate of excitation hopping via both a dipole-dipole mechanism and a super-exchange mechanism to the neighboring sites of the cation was calculated to be 5.4 x 10(9) s(-1) for the PF(6)- crystal. Anisotropic diffusion constants estimated from the hopping rates and lengths in the PF(6)- crystal are 9.3 x 10(-6), 9.1 x 10(-6), and 1.4 x 10(-6) cm(2)s(-1) along the a axis, the b axis, and the c axis, respectively, which are compared with an isotropic diffusion constant, 1.3 x 10(-6) cm(2) s(-1), estimated from the pseudo-bimolecular rate constant of excitation transfer to [Os(bpy)(3)](2+), using an isotropic Smoluchowski equation. A multiexponential emission decay of [Ru(0.885)Os(0.115)(bpy)(3)](PF(6))(2) was also simulated to determined the limiting rate of excitation transfer to [Os(bpy)(3)](2+) at the van der Waals distance (2.6 x 10(11) s(-1)). The magnitude of beta determined is 6.5 and 11.5 nm(-1) for the ClO(4)- and the SbF(6)- salt crystals, respectively, on reference to that of beta (10 nm(-1)) for the PF(6)- salt crystal.