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Showing papers in "ChemInform in 1993"


MonographDOI
TL;DR: Anomeric effect -how it came to be postulated, John T. Edward anomeric and associated stereoeleconic effects - scope and controversy, Gregory R.J. Thatcher intramolecular strategies and stereoelectronic effects - glycosides and orthoesters hydrolysis revisited, P.H.
Abstract: Anomeric effect - how it came to be postulated, John T. Edward anomeric and associated stereoeleconic effects - scope and controversy, Gregory R.J. Thatcher intramolecular strategies and stereoelectronic effects - glycosides and orthoesters hydrolysis revisited, P. Deslongchamps anomeric and gauche effects - some basic stereoelectronics, Anthony J. Kirby and Nicholas H. Williams anomeric effects - an iconoclastic view, Charles L. Perrin no kinetic anomeric effect in reactions of acetal derivatives, Michael L. Sinnott involvement of ns interactions in glycoside cleavage, C. Webster Andrews et al X-C-Z anomeric effect and Y-C-C-Z gauch effect (X,Y = O,S Z = O,N) - evaluation of the steric, electrostatic and orbital interaction components, B. Mario Pinto and Ronald Y.N. Leung origin and quantitative modeling of anomeric effect, Peter A. Petillo and Laura E. Lerner application of quantum theory of atoms in molecules to study of anomeric effect in dimethoxymethane, N.H. Westiuk et al anomeric and reverse anomeric effect in acetals and related functions, F. Grein glycosylmanganese complexes and anomeric anomalies - the next generation?, Philip DeShong et al do stereoelectronic effects control the structure and reactivity of trigonal- bipyramidal phosphoesters?, Philip Tole and Carmay Lim steroelectronic effects in pentaoxysulfuranes - putative intermediates in sulfuryl-group transfer, Dale R. Cameron and Gregory R.J. Thatcher O-C-N anomeric effect in nucleosides - a major factor underlying the experimentally observed eastern barrier to pseudorotation, Ravi K. Jalluri.

244 citations




Journal ArticleDOI
TL;DR: A series of new fluorescent labeling reagents based on sulfoindocyanine dyes has been developed as discussed by the authors, which can be conjugated to antibodies, avidin, DNA, lipids, polymers, and other amino-groupcontaining materials.
Abstract: A series of new fluorescent labeling reagents based on sulfoindocyanine dyes has been developed. We describe the synthesis and properties of these reagents. They contain succinimidyl ester reactive groups and can be readily conjugated to antibodies, avidin, DNA, lipids, polymers, and other amino-group-containing materials. The labeling reagents are water soluble, pH insensitive, and show much reduced dye aggregation under labeling conditions. One of the reagents, Cy3, can be excited with the 488-, 514- and 532-nm laser lines and is optimally excited with the 546-nm mercury arc line. Another, Cy5, can be excited with the 633-nm HeNe and 647-nm Kr laser lines available with many flow cytometers and confocal laser-scanning microscopes. New laser diodes emitting near 650 nm should also be excellent excitation sources for Cy5.

151 citations


Book ChapterDOI
TL;DR: Heterogeneous catalysis is rapidly developing from a black box technology employed by the chemical engineer and becoming a frontier area of modern physical science as mentioned in this paper, encouraged by parallel developments in surface science, in in situ methods suitable for studies of the working catalyst, in our understanding of reactivity, kinetics and mechanism, and of relevant and cognate theoretical studies.
Abstract: Heterogeneous catalysis is rapidly developing from a black box technology employed by the chemical engineer and becoming a frontier area of modern physical science. Progress is encouraged by parallel developments in surface science, in in situ methods suitable for studies of the working catalyst, in our understanding of reactivity, kinetics and mechanism, and of relevant and cognate theoretical studies. This improved insight into catalysis at the molecular level has increased the rate of catalyst development and is changing catalytic practise. This is therefore an appropriate time to review the field and to set the agenda for future progress.

134 citations







Journal ArticleDOI
I. D. Brown1
TL;DR: In this paper, the ideal chemical structure and bond geometry can be predicted using the bondvalence model which is developed in some detail, and the resulting rich crystal chemistry is often associated with important physical properties such as ferroelectricity and superconductivity.
Abstract: The structures observed for many inorganic solids are the result of a compromise between the conflicting requirements of chemical bonding and threedimensional geometry. The ideal chemical structure and bond geometry can be predicted using the bondvalence model which is developed in some detail. The constraints imposed on this geometry when the ideal structure is mapped into three-dimensional space require, in many cases, that ideal bond lengths be strained. Particularly in compounds containing bonds of intermediate strength (e.g. the oxides and halides of di- and trivalent cations), the relaxation of this strain can result in non-stoichiometry, stabilization of unusual oxidation states, distortion of bonding environments and lowering of symmetry. The resulting rich crystal chemistry is often associated with important physical properties such as ferroelectricity and superconductivity. Examples are given which show that these properties can, at least in some cases, be derived directly from the chemical formula by considering the problems of generating a structure that conforms to both the chemical and the spatial constraints.

Journal ArticleDOI
TL;DR: In this article, a simple and convenient method for measuring antioxidant efficiencies in a model system consisting of micelles of sodium dodecyl sulfate (SDS) with added linoleic acid was presented.
Abstract: This paper presents a simple and convenient method for measuring antioxidant efficiencies in a model system consisting of micelles of sodium dodecyl sulfate (SDS) with added linoleic acid. The analytical method involves following the development of absorption at 230 nm due to the conjugated diene hydroperoxide of linoleic acid; 2,2'-azobis(2-amidinopropane) dihydrochloride (ABAP) is used as the initiator. The antioxidant efficiency of an antioxidant is defined as AE=k inh /k p , where k inh is the rate constant for reaction of the peroxyl radical from linoleic acid with the antioxidant (eq 7 in the text) and k p is the propagation rate constant for autoxidation of linoleic acid (eq 5)

Journal ArticleDOI
TL;DR: In this article, a new approach for the preparation of nanoparticles is presented, based on control of the gelification phenomenon of alginate by calcium ions, and it leads to small particles of a wide range of very well-defined sizes (250-850 nm).
Abstract: A new approach for the preparation of nanoparticles is presented. The method is based on control of the gelification phenomenon of alginate by calcium ions, and it leads to small particles of a wide range of very well-defined sizes (250–850 nm) depending on the alginate concentration. The particles are formed in a sodium alginate solution by addition of calcium chloride and then poly-L-lysine. The concentrations of sodium alginate and of calcium chloride were lower than those required for gel formation and corresponded to the formation of a pregel state. The size of the particles formed is greatly dependent on the order of addition of calcium and poly-L-lysine to the sodium alginate solution. This phenomenon can be attributed to the difference in the nature of the interactions between calcium and alginate and between poly-L-lysine and alginate. Furthermore, the data indicate that the formation of the particles probably occurs during the addition of the first component to the sodium alginate solution. Evaluation of the drug-loading capacity was done with doxorubicin as a drug model. The results indicate that alginate nanoparticles are interesting carriers because the drug-loading capacity could be >50 mg of doxorubicin per 100 mg of alginate.

Journal ArticleDOI
TL;DR: In this article, a Monte Carlo technique was used to obtain accurate theoretical mobilities for carbon cluster cations, which indicated that linear structures exist up to C[sub 10[sup +]].
Abstract: Carbon clusters are generated by laser desorption. Mass-selected beams are then pulse injected into an ion chromatography (IC) device. This device temporally and spatially separates the beam into its isomeric components. Arrival time distributions (ATDs) are then measured at the detector. From these distributions, accurate mobilities are obtained for each isomeric component, along with the the fractional abundance of each isomer. Different isomer structures are calculated using quantum chemical methods. A Monte Carlo technique uses these structures to obtain accurate theoretical mobilities. Comparison of theory with experiment allows unambiguous structural assignment of the various families of isomers present in the cluster beam. The results indicate that, for carbon cluster cations, linear structures exist up to C[sub 10[sup +]]. Several families of planar ring systems begin with monocyclic rings (ring I), which first appear at C[sub 7[sup +]], and persist beyond C[sub 40[sup +]]. Bicyclic rings (ring II) are first observed at C[sub 21[sup +]] and persist beyond C[sub 40[sup +]], followed by tricyclic rings (ring III, initiated at C[sub 30[sup +]]) and tetracyclic rings (ring IV, initiated at C[sub 40[sup +]]). A 3-dimensional family we label as 3-D rings begins at C[sub 29[sup +]], whose structure is not yet unambiguouslymore » assigned. This family never exceeds 5% of the ions at any cluster size. Finally, the first fullerene is observed at C[sub 30[sup +]], with this family dominating above C[sub 50[sup +]]. 32 refs., 14 figs., 4 tabs.« less


Journal ArticleDOI
TL;DR: In this article, the staging phenomenon was observed by X-ray diffraction (XRD) and the first and second stage compounds were identified as a commensurate structure in which lithium atoms form a close-packed two-dimensional array.
Abstract: Electrochemical reduction of natural graphite was carried out in 1M LiClO[sub 4] ethylene carbonate (EC)/1,2-dimethoxyethane (DME) solution at 30 C. Natural graphite was reduced stepwise to LiC[sub 6]. The staging phenomenon was observed by X-ray diffraction (XRD). The first stage and the second stage compounds were identified as a commensurate structure in which lithium atoms form a close-packed two-dimensional array. A second-stage compound (LiC[sub 18]) with a different in-plane lithium ordering based on a LiC[sub 9] two-dimensional packing in lithium intercalated sheets also was observed; also third, fourth-stage compounds were identified. The electrochemical oxidation of the first-stage compound (LiC[sub 6]) was examined and shown to reversible over the entire range, i.e., C[sub 6] + xLi [r reversible] Li[sub x]C[sub 6]. The reaction mechanism for the reduction of graphite and the oxidation of the first-stage compound are discussed in relation to the staging phenomenon from the detailed open-circuit voltage and XRD data. The chemical potential of LiC[sub 6] was estimated to be [minus]3.6 kcal mol from the observed reversible potential. The feasibility of using a lithium-graphite intercalation compound in lithium ion (shuttlecock) cells is described, and the innovative secondary systems, C[sub 6]/LiCoO[sub 2] and C[sub 6]/LiNiO[sub 2] fabricated in discharged states,more » are demonstrated.« less

Journal ArticleDOI
TL;DR: In this article, the processes of passive oxidation, deposit-induced corrosion, active oxidation, scale/substance interactions, and scale volatility are studied in the case of high-purity SiC and Si3N4 in pure oxygen, giving attention to such secondary elements in the ceramics as water and CO2 oxidants, combustion environment impurities, and thermal cycling.
Abstract: The processes of passive oxidation, deposit-induced corrosion, active oxidation, scale/substance interactions, and scale volatility are presently studied in the case of high-purity SiC and Si3N4 in pure oxygen, giving attention to such secondary elements in the ceramics as water and CO2 oxidants, combustion environment impurities, and thermal cycling. Deposit-induced corrosion is discussed for the cases of NaSO4 as well as vanadate and oxide-slag deposits; issues associated with the active-to-passive oxidation transition are noted.




Journal ArticleDOI
TL;DR: In this article, the Universal Force Field (UFF) was used to predict the structures of a variety of organic molecules, including unstrained and uncongested hydrocarbons, silanes, alkenes, saturated amines, saturated ethers and phosphines.
Abstract: The application of a Universal force field (UFF) to the treatment of organic molecules is described. The ability of the force field to predict the structures of a variety of organic molecules is examined, and the results are compared with the MM2 or MM3 force fields. UFF correctly predicts the structures of unstrained and uncongested hydrocarbons, silanes, alkenes, saturated amines, saturated ethers and phosphines, aromatic systems, and simple unconjugated multiple bond containing compounds such as nitriles, ketones, and imines well

Journal ArticleDOI
Ryoji Noyori1
TL;DR: A wide range of optically active substances can be synthesized catalytically by the appropriate combination of transition metals or main group elements and suitably designed chiral organic elements as discussed by the authors.
Abstract: Homogeneous catalysis using chiral metal complexes provides a general principle for chemical multiplication of chirality. A wide range of optically active substances can be synthesized catalytically by the appropriate combination of transition metals or main group elements and suitably designed chiral organic elements. This chemistry is useful not only for stereoselective preparation of chiral compounds in laboratories but also even on industrial level. The recent progress in this field greatly raised the potential of organic synthesis in general. The current status is discussed.


Journal ArticleDOI
TL;DR: In this paper, a diamido diacid diphenyl fulleroid derivative was designed specifically to inhibit an HIV enzyme and detailed synthesis and mass spectrometric analysis of the water-soluble, biologically active methanofullerene are described.
Abstract: A diamido diacid diphenyl fulleroid derivative was designed specifically to inhibit an HIV enzyme. The detailed synthesis and mass spectrometric analysis of the water-soluble, biologically active methanofullerene are described. The compound was prepared in three steps from C[sub 60] via a suitably diphenyldiazomethane. High-resolution mass spectrometric analysis was possible only under mild matrix-assisted laser desorption/ionization Fourier transform mass spectrometry conditions. Direct infrared or ultraviolet laser desorption resulted exclusively in observation of C[sub 60] ions, in either positive or negative mode. 13 refs., 3 figs.



Journal ArticleDOI
Leslie S. Ettre1


Journal ArticleDOI
TL;DR: In this paper, the authors discuss the biological importance of copper thiosemicarbazone complexes and their applications in the field of chemical engineering, such as chemical synthesis, chemical engineering and electrical engineering.
Abstract: A. Introduction (i) Biological importance of copper(H) complexes (ii) Historical interest in copper thiosemicarbazone complexes (iii) Synthesis (iv) Bonding types B. Crystal structures of copper thiosemicarbazones C. Magnetic studies (i) Magnetic moments (ii) Electron spin resonance spectra (a) Bis(thiosemicarbazones), Cu(SNNS) (b) Tridentate thiosemicarbazones, Cu(ONS) (c) Tridentate thiosemicarbazones, Cu(NNS) (d) Pentadentate thiosemicarbazones, Cu(SNNNS) D.Spectralstudies.. (i) Infrared spectra (ii) Electronic spectra E. Thermal studies F. Electrochemical studies G. Recent biological studies of thiosemicarbazones H. Conclusion References 50 50 51 52 52 53 56 56 57 57 58 59 60 60 60 61 63 64 65 66 67