Functionalization of α-Aminonicotinonitrile: A New Entry for Synthesis of Pyrazolo[3,4-b]pyridine,Pyrido[2,3-d]pyrimidine,and 1,8-Naphthyridine Derivatives

Russian Journal of General Chemistry - Functionalization of α-aminopyridine to a new series of pyridine and fused pyridine derivatives has been achieved via its reaction with a variety of...     

Interconvertible multiple photoluminescence color of a gold(i) isocyanide complex in the solid state: solvent-induced blue-shifted and mechano-responsive red-shifted photoluminescence

In this study, we report the interconvertible tetracolored solid state photoluminescence of gold(i) isocyanide complex 2 upon various external stimuli through solid state structural changes. Soaking complex 2 in acetone yields blue emission as a result of the formation of 2B. The subsequent removal of acetone yields 2G through a crystal-to-crystal phase transition, which exhibits green emission. This green-emitting solid 2G exhibits stepwise emission color changes to yellow and then to orange upon mechanical stimulation by ball-milling, which corresponds to the formation of 2Y and 2O, respectively. 2B could be recovered upon the addition of acetone to 2G, 2Y, and 2O. Thus, these four emitting solid states of 2 can be switched between repeatedly by means of acetone soaking and the application of mechanical stimulation. Importantly, single crystal and powder X-ray diffraction (PXRD) studies fully show the detailed molecular arrangements of 2B, 2G, and 2Y. This is the first mechanochromic compound to show interconvertible four color emission in the solid state. We also present the first example of using PXRD measurements and the Rietveld refinement technique for the structural analysis of a ground powder in a luminescence mechanochromism study. We obtained complete molecular-level structural information of the crystalline states of 2B, 2G, 2Y, and 2O. In comparison with a more solvophobic analogue 1, we suggest that the weak interaction of 2 with acetone in the solid state would allow a solvent inclusion/release mode, which is an important structural factor for the unprecedented multicolor mechanochromic luminescence.     

Reaction dynamics of V(a4FJ)+NO-->VO(X 4Sigma-)+N studied by a crossed-beam laser-induced fluorescence technique

The dynamics of the reaction, V(a 4FJ)+NO-->VO(X 4Sigma-)+N was studied by using a crossed-beam technique at 16.4 kJ/mol of collision energy. The V atomic beam was generated by laser vaporization and crossed with the O2 beam at a right angle. The laser-induced fluorescence (LIF) for the transition of VO(B 4Pi-X 4Sigma) was used to determine the rotational state distribution of the reaction product in the vibrational ground state. Almost pure V(a 4FJ) beam was obtained by using the mixture of NH3 with N2 as a carrier gas. Comparing the LIF spectra of VO measured for two carrier gases, i.e., NH3N2 and pure N2, it was concluded that the vibrational ground state of VO(X 4Sigma-) is formed almost entirely from the reaction of V(a 4FJ) and the contribution of the metastable V(a 6DJ) is negligible. The observed rotational distribution was similar to a statistical prior prediction, and suggested that the title reaction proceeds via a long-lived intermediate, which is consistent with an electron transfer mechanism.     

Lewis acid-assisted nucleophilic substitution of fullerene epoxide

[Structure: see text] A 1,4-bis(phenyl)-1,4-dihydro[60]fullerene resulting from an efficient nucleophilic substitution has been obtained by reaction of a fullerene epoxide, C60O, with nucleophilic aromatic compounds in the presence of boron trifluoride etherate as a Lewis acid.     

Cyclic-tri(N-methyl-meta-benzamide)s: substituent effects on the bowl-shaped conformation in the crystal and solution states

Cyclic trimers of 3-(N-alkylamino)benzoic acid (calix[3]amides) with various substituents at the meta position of the phenyl rings were synthesized and the effects of the substituents on the crystal structures and energy profiles in solution were examined. The calixamides existed in a syn conformation in the crystal state, and this was also the major conformation in solution, especially in polar solvents. The energy barrier between syn and anti conformers in the solution was not significantly affected by substituents (12.7-14.0 kcal/mol). The effect of the substituent on the temperature dependence of the syn/anti ratio are discussed.     

Formation and its mechanism of copper metal layers at surface by annealing in reduced atmosphere in CuO–Li2O–Nb2O5–SiO2 glass

A trace amount (0.5 mol%) of CuO-doped 40Li₂O–32Nb₂O₅–28SiO₂ glass (mol%) exhibits the formation of copper metal layers at the glass surface by annealing at temperatures (530 °C) below the glass transition temperature (544 °C) in the reduced atmosphere of 7% H₂–93%Ar. The coordination state of copper ions is examined from optical absorption and Fourier transform infrared (FT-IR) spectrum measurements, indicating the formation of Si–OH and Si–H bonds due to the diffusion of hydrogen into the inside of the glass and the reduction of Cu⁺ and Cu²⁺ ions. The mechanism of the formation of copper metals at the surface is proposed, in which the key points are the reduction of Cu²⁺ to Cu⁺ ions due to the hydrogen and the migration of Cu⁺ ions in the interior of the glass to the surface. The first finding on copper metal layers at the glass surface might have a potential for practical applications such as electrodes in glass.     

Existence of limit cycles for Liénard-type systems with p-Laplacian

The purpose of this paper is to give sufficient conditions under which an equivalent system to the equation has at least one stable limit cycle, where is the one-dimensional p-Laplacian. The main results are proved by means of phase plane analysis with the Poincaré-Bendixson theorem. Sufficient conditions are also given for the origin to be unstable and for all solutions to be bounded in the future. Jitsuro Sugie: Supported in part by Grant-in-Aid for Scientific Research 16540152     

Modified Markó’s aerobic oxidation of alcohols under atmospheric pressure with air or molecular oxygen at room temperature

A modified version of Markó’s aerobic oxidation procedure, using highly pure (99.995+%) CuCl with 4,7-diphenyl-1,10-phenanthroline (dpPhen), DBAD, and Cs₂CO₃ (98% purity) successfully oxidized primary and secondary alcohols to the corresponding aldehydes and ketones in excellent yield at room temperature with either air or molecular oxygen under atmospheric pressure.     

Electrical conductivity and dynamics of quasi-solidified lithium-ion conducting ionic liquid at oxide particle surfaces

Lithium ion conducting solid-state composites consisting of lithium ion conducting ionic liquid, lithium bis(trifluoromethanesulfonyl)amide (Li-TFSA) dissolved 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)amide (EMI-TFSA), denoted by [yMLi⁺][EMI⁺][TFSA⁻] in this study, and various oxide particles such as SiO₂, Al₂O₃, TiO₂ (anatase and rutile) and 3YSZ are synthesized via a liquid route for the molar concentration of lithium, y, to be 1. The composite consists of SiO₂ and the ionic liquid with y = 0.2 was also prepared. The ionic liquid are quasi-solidified at the above oxide particle surfaces when x is below 40 for y = 1 and x is below 30 for y = 0.2, corresponding to the confinable thickness of the ionic liquid at the oxides' surfaces to be approximately 5-10 nm regardless of the oxide compositions. The electrical conductivities of x vol.%[yMLi⁺][EMI⁺][TFSA^-]-SiO₂, Al₂O₃, TiO₂s or 3YSZ composites are evaluated by ac impedance measurements. The quasi-solid-state composites exhibited liquid-like high apparent conductivity, e.g. 10^− 3.3-10^− 2.0 S cm^− 1 in the temperature range of 323-538 K for SiO₂-ionic liquid composites with y = 1. The self-diffusion coefficients of the constituent species of x vol.% [yMLi⁺][EMI⁺][TFSA⁻] (x is below 40, y = 0.2 and 1) − SiO₂ are evaluated by the Pulse Gradient Spin Echo (PGSE)-NMR technique in the temperature range of 298-348 K. By the quasi-solidification of the ionic liquid at SiO₂ particle surfaces, the absolute values of the diffusion coefficients of all constituent species decreased. The SiO₂ surfaces work to promote ionization of ion pair, [EMI⁺][TFSA⁻], while significant influence on the solvation coordination, [Li(TFSA)_n + 1]ⁿ⁻, was not observed. The apparent transport numbers of Li-containing species both in the bulk and the quasi-solidified ionic liquid showed similar values with each other, which was evaluated to be in the range of 0.010-0.017 for y = 0.2 and 0.051-0.093 for y = 1 in the abovementioned temperature range.     

Determination of simazine in water samples by HPLC after preconcentration with diatomaceous earth

A sensitive and selective batch adsorption method is proposed for the preconcentration and determination of simazine. Simazine was preconcentrated on diatomaceous earth as an adsorbent and then determined by high-performance liquid chromatography (HPLC). Several parameters on the recovery of the analyte were investigated. The experimental results showed that it was possible to obtain quantitative analysis when the solution pH was 2 using 100 mL of validation solution containing 1.5 μg of simazine and 5 mL of ethanol as an eluent. Recovery of simazine was 89.0 ± 1.6% with a relative standard deviation for seven determinations of 1.5% under optimum conditions. The maximum preconcentration factor was 100 for simazine when 500 mL of sample solution volume was used. The linear range of calibration curve was 1-200 ng mL⁻¹ with a correlation coefficient of 0.996 and the detection limit (3S/N) was 0.3 ng mL⁻¹. The capacity of the adsorbent was also examined and found to be 1.1 mg g⁻¹ for simazine. The proposed method was successfully applied to the determination of simazine in river water with high precision and accuracy.