Synthetic approach to kendomycin: preparation of the C-glycosidic core

Synthesis of the C13-C19 C-glycoside portion of kendomycin was achieved via oxidative pyran cyclization and Claisen rearrangement to construct the fully functionalized aromatic ring.     

Synthetic studies on sugar-fused erinacines

Samarium-mediated 7-endo-trig radical cyclization afforded excellent stereocontrol of the four contiguous asymmetric centers present in the 6-7-6 tricyclic cores of the (sugar-fused) erinacines E, F, and G.     

Rapid and sensitive determination of aprindine in serum by gas chromatography using a surface ionization detector

A rapid and highly sensitive method for the determination in serum of aprindine, an antiarrhythmic drug, was developed employing gas chromatography with a surface ionization detector. No interfering peak from endogenous substances appeared when an organic phase was directly injected into the system after single extraction from a serum sample. A standard curve obtained was linear up to the serum level of 6 micrograms/ml, and the limit of sensitivity was 16 pg. The method described is applicable to routine therapeutic monitoring of serum concentrations of aprindine.     

Determination of the angular separation and the spectra of two-point sources from spectral coherence measurements

We present a novel method not only for determining the angular separation of unknown two-point spectral sources but also for obtaining each of their spectral profiles from measurements of both their complex degree of spectral coherence and their spectra across an observation area in the space-frequency domain. The theoretical predictions are fully proved by an experimental demonstration with a pair of uncorrelated two-point spectral sources.     

Chemical Processing of Potassium Substituted (Pb0.6Ba0.4)Nb2O6 Powders and Thin Films Through Metallo-Organics

Highly oriented tungsten bronze K_0.4(Pb_0.6Ba_0.4)_0.8Nb₂O₆ ferroelectric thin films have been prepared from metal alkoxides and metal acetate by chemical process. The formation of solid solution with potassium was found to be very effective to form the tungsten bronze phase at lower temperatures compared with (Pb_0.6Ba_0.4)Nb₂O₆. The amount of potassium in the composition of K_x(Pb_0.6Ba_0.4)_{1 – x/2}Nb₂O₆ [0 x 0.4] is also important to crystallize in the tungsten bronze phase. K_0.4(Pb_0.6Ba_0.4)_0.8Nb₂O₆ films with c-axis preferred orientation were successfully synthesized on MgO(1 0 0) and Pt(1 0 0)/MgO(1 0 0) substrates above 700°C. KPBN60 thin film on Pt(1 0 0)/MgO(1 0 0) showed a remnant polarization of 20 C/cm² and a coercive field of 140 kV/cm at –150°C.     

Probing stepwise complexation in phenylazomethine dendrimers by a metallo-porphyrin core

A series of dendritic phenylazomethines (DPA), which have a meso-substituted zinc porphyrin core (DPAGX-ZnP, X = 1-4), were synthesized. Structural studies of these dendrimers were carried out using Tri-SEC (triple detection after size exclusion chromatography), intrinsic viscosity analysis, TEM (tunneling electron microscopy), and molecular modeling calculations by AM1. As a result, a sphere-like structure within a single-nanometer scale (R(h) = 22 A for DPAG4-ZnP) was observed. In addition, encapsulating effects by the DPA shell in the larger dendrimers were confirmed as fundamental properties, based on the UV-vis abosorption spectra, cyclic voltammograms, and 1H NMR spin-lattice relaxation times (T1). The DPAGX-ZnP acts as a multi-metal ion reservoir for SnCl2 and FeCl3. The generation-4 dendrimer (DPAG4-ZnP) can take up to 60 molar amounts of metal complexes around the porphyrin core. A quantitative study of the metal assembling reaction by UV-vis titration revealed stepwise layer-by-layer complexations from the inner imines nearest to the core to the surface. The redox behavior and fluorescence of the zinc porphyrin in these metal-assembled dendrimers also support the stepwise complexation of the metal ion. These analyses suggest that the finely assembled metal complexes in a dendrimer architecture strongly affect the electronic status of the porphyrin core. Results from transient absorption measurements strongly indicate a very fast electron transfer on a subpicosecond time scale between the core and assembled metal complexes.     

Structural analysis of certain linear operators representing chemical network systems via the existence and uniqueness theorems of spectral resolution. II

The methodology and theoretical framework of Part I of this series of articles have been further developed to the setting of the Banach algebra B (??), of all bounded operators acting on a Banach space ??. Using the above setting B (??), certain dynamical systems of chemical kinetic equations are illustrated in conjunction with Part I and with the analysis of more general systems, some of which will be made in Part III of this series of articles. The main theorem and its auxiliary theorem in the present article elucidate in a unifying manner the structure and the underlying pattern of the spectral symmetry of linear operators (acting on Banach spaces and Hilbert spaces) that are investigated in each of the research fields of dynamical systems and quantum chemistry involving the spectral symmetry of alternant hydrocarbons. © 1995 John Wiley & Sons, Inc.     

The Functional Delta Existence Theorem and the Reduction of a Proof of the Fukui Conjecture to That of the Special Functional Asymptotic Linearity Theorem

This article establishes a fundamental existence theorem, called the Functional Delta Existence Theorem (DET), which is significant for a new development in the repeat space theory (RST) and also for elucidating an empirical asymptotic principle from experimental chemistry. By using the Functional DET, we reduce a proof of the Fukui conjecture to that of a special and simpler version of the Asymptotic Linearity Theorem (ALT). This reduction provides a basis for the forthcoming series of articles entitled “Proof of the Fukui conjecture via resolution of singularities and related methods”. A proof of the Functional DET is given here in a unifying manner so that an investigative link is formed among: (i) fundamental methodology in the RST, which is referred to as the approach via the aspect of form and general topology, (ii) frontier electron theory of reactivity indices, and (iii) the Shingu–Fujimoto empirical asymptotic principle for long chain molecules.     

The courant-fischer theorem and the spectrum of selfadjoint block band Toeplitz operators

We show that ifT(F) is a selfadjoint block Toeplitz operator generated by a trigonometric matrix polynomialF, then the spectrum ofT(F) as well as the limiting set (F) of the eigenvalues of the truncationsT _n (F) is the union of a finite collection of segments (the spectral range ofF) and at most a finite set of points for which we give an upper bound.