Synthesis and Characterization of a Novel Cyclomatrix Phosphazene Polymer

Novel phosphazene cyclomatrix network polymers were synthesized via the nucleophilic displacement of activated nitro groups of tri(4-nitrophenoxy)tri(phenoxy)cyclotriphosphazene and hexa(p-nitrophenoxy) cyclotriphosphazene with hydroxyls of bisphenol A. Both monomers and polymers were characterized by Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance, and elemental analysis measurements, and their structures were identified. Thermal properties of polymers were investigated using dynamic thermogravimetric analysis in air. The results demonstrated that both cyclomatrix phosphazene polymers 4 and 6 were of excellent thermal stability, and their char yields in air at 800°C were 45.1 and 43.2%, respectively. According to combustion phenomenon, polymer 4 was supposed to be processed with a good flame-retardant property because of its excellent crosslinked structure during pyrolysis or combustion. However, polymer 6 yielded the opposite result. Translated from the Journal of Beijing University of Chemical Technology, 2005, 32(2) (in Chinese) This study was supported by the National High Technology Research and Development Foundation (2002AADF3202)     

Three new ɑ-pyrone derivatives induced by chemical epigenetic manipulation of Penicillium herquei,an endophytic fungus isolated from Cordyceps sinensis

Abstract

Chemical epigenetic manipulation was applied to explore secondary metabolite of an endophytic fungus Penicillium herquei, which was obtained from the fruiting body of Cordyceps sinensis, and three previously undescribed polyketides with pyran-2-one scaffold were isolated from its fermentation broth containing 10?mg/L 5-aza-2-deoxycytidine (a frequently-used DNA methyltransferase inhibitor). The structures of these new compounds were identified by extensive spectroscopic analyses, and their absolute configurations were elucidated by quantum chemical ECD calculations.     

ON THE PHOSPHORUS-31 CHEMICAL SHIFTS OF SUBSTITUTED TRIARYLPHOSPHINES

Abstract

The ³¹P chemical shifts of eleven (4-ZC₆H₄)₃P compounds show a slight correlation with the Hammet [sgrave]para constant of Z. The unusually large upfield chemical shifts of (2-ZC₆H₄)₃P compounds are attributed to an extreme “gamma” effect caused by the restricted conformations due to the steric influence of the ortho substituents. Chemical shifts are given for about thirty triarylphosphines, and group contributions to phosphine chemical shifts are listed for twenty-one aryl groups.     

History and Heritage of Scientific and Technical Information Systems

Die nach 1998 zweite „Conference on the History and Heritage of Scientific and Technical Information Systems”︁ brachte vom 15. bis 17. November 2002 in Philadelphia, Pennsylvania, Informationswissenschaftler, Chemiker, Wissenschafts‐ und Technikhistoriker sowie Pioniere und Zeitzeugen zusammen. Mit dem Schwerpunkt auf der Zeit nach dem zweiten Weltkrieg wurde sowohl die Entwicklung konventioneller und maschineller Informationssysteme als auch die Rolle von Einzelpersonen und Institutionen bei der Entwicklung solcher Systeme und deren Infrastruktur gewürdigt. Mehr als 100 Teilnehmer aus den Vereinigten Staaten, aber auch aus Australien, Deutschland, Finnland, Frankreich, Großbritannien, Irland, Kanada, dem Kongo, Rußland, Schweden und Slowenien besuchten diese von der American Society for Information Science and Technology (ASIST) und der Chemical Heritage Foundation (CHF) veranstaltete und von Mary Ellen Bowden und W. Boyd Rayward organisierte Konferenz.     

Analytical Chemistry,Past, Present and Future*This paper is dedicated to the Editorial Board of Analytical Letters.

ABSTRACT

Analytical Chemistry as a science has its own history as well as an important present and a sure future.

The aim of this paper is to demonstrate the role of Analytical Chemistry as a science and of Chemical Analysis as an art in the development of human society.

The correlation between method and instrument hyphenated by the sample is discussed along a long period of active Analytical Chemistry.

The connection between theory of Analytical Chemistry and the practice of chemical analysis enables us to be sure of the future of Analytical Chemistry.

We must consider that to do science it is necessary to know the history of science as well as to make research to be used not only in the present, but also in the near future.

Surely, Analytical Chemistry as a real scientific area will be on the top of sciences in the next century.     

Lavoisier's Achievement; More Than a Chemical Revolution

Abstract

The Chemical Revolution of the late eighteenth century consisted essentially of combustion being explained by the addition of oxygen rather than by the removal of phlogiston. This has been seen as the “paradigm shift” of a scientific revolution in the familiar Kuhnian sense. Yet Lavoisier helped to change chemistry in several other ways as well, particularly by the introduction of a new chemical language. This reorganisation of chemistry, at a time when it was being swamped with many new substances, has great similarity to the slightly earlier systematisation of botany by Linnaeus through the introduction of a binomial nomenclature. A further parallel in the late eighteenth century was the introduction of the metric system, which also introduced a new language. Yet, however one understands the Chemical Revolution, Lavoisier clearly made an enormous difference, not only to the internal science of chemistry, but also to its status. By the end of the 1700s, chemistry had become something of a model science.     

Chemical Imaging for PAH Analysis in Particulate Materials

Abstract

Chemical imaging is a new analytical science, related to a combination of spatial and chemical resolutions. Several new chemical imaging tools have been developed and applied to environmental analysis. The advantages of such methods, which provide simultaneous morphological/geometrical and chemical speciation, are pointed out and exemplified in several environmental analytical applications. These include fast analysis of PAH contaminated aerosols at low concentrations, analysis of contaminated quartz sand particles, as well as improvement of laser induced fluorescence detection of PAH compounds in natural water, in the presence of various microparticles. It is shown that chemical imaging has a considerable potential in environmental applications and can provide detailed and unique information when particulate materials are concerned.     

Acutifoliside,a novel benzoic acid glycoside from Salix acutifolia

Ultra high-performance liquid chromatography–mass spectrometry (UHPLC–MS) profiling of a polar solvent extract of juvenile stem tissue of Salix acutifolia Willd. identified a range of phenolic metabolites. Salicortin, 1, a well-known salicinoid, was the major compound present and the study identified young stem tissue of this species as a potential source of this compound for future studies. Three further known metabolites (salicin 2, catechin 3 and tremuloidin 4) were also present. The UHPLC–MS analysis also revealed the presence of a further, less polar, unknown compound, which was isolated via HPLC peak collection. The structure was elucidated by high-resolution mass spectroscopic analysis, 1- and 2-D NMR analysis and chemical derivatisation and was shown to be a novel benzoic acid glycoside 5, which we have named as acutifoliside.     

Chemical Analyses of Canadian Reference Samples: SY-2 and SY-3

Abstract

Chemical analyses of the major and some of the minor constituents are reported for two new Canadian silicate rock standards recently introduced by the Department of Energy, Mines and Resources. To date quantitative chemical analyses have not yet been reported for these samples. The compositions of these rocks offer a useful range of values that are not currently covered by existing silicate rock standards.     

H Nmr Spectra of Oligosaccharide Substituted Cyclodextrins

ABSTRACT

¹H NMR spectra of some oligosaccharide substituted cyclodextrins composed of only α-D-glucose units are analysed. Chemical shifts of protons of each glucosyl group of the chain were determined by experiments with the HOHAHA pulse technique. In spite of the similar kinds of protons, dispersion of chemical shifts is observed. The most dispersed proton is the anomeric proton, and the largest change in the chemical shifts is 0.5 ppm.     

Neutral solvent/crown ether interactions, 4. Crystallization and low temperature (−150°C) structural characterization of 18-crown-6 · 2(CH3CN)

The crystal structure of 18-crown-6 · 2(CH₃CN) has been determined via data collection at –150°C. The structure consists of two crown molecules each hydrogen bonded to two acetonitrile moieties in the asymmetric unit, each residing around a center of inversion. The crown ethers display their fullD _3d symmetry; methyl ... O contacts range from 3.189(8) to 3.598(8) Å. There are no close contacts indicative of any interaction between the crown/2(CH₃CN) units. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82056 (14 pages).For Part 3, see reference [1]     

Molecular conformations at the cellulose–water interface

¹³C-NMR chemical shifts were measured for C-4 and C-6 in a collection of eight crystalline glucoses and glucosides. The influence of the hydroxymethyl conformation was greater at C-4 than at C-6, with mean chemical shifts for gauche–trans molecules displaced 3.1 ppm (C-4) and 2.5 ppm (C-6) relative to gauche–gauche molecules. This information was used to interpret ¹³C-NMR spectra of crystalline celluloses. Chemical shifts for C-4 in the crystallite cores of celluloses I and II differed by just 0.2 ppm, but the corresponding chemical shifts for well-ordered crystallite surfaces differed by 3.0 ppm. The separation between crystallite-surface signals was attributed to different hydroxymethyl conformations at the cellulose–water interface, i.e., gauche–gauche and gauche–trans on crystallites of cellulose I and cellulose II, respectively. A broad C-4 signal in the spectrum of cellulose II indicated gauche–gauche conformations in disordered cellulose. Chemical shifts for C-6 were consistent with these conformations.     

New cytotoxic spongian-class rearranged diterpenes from a marine sponge

Chemical investigation of an Okinawan marine sponge resulted in the isolation of two new spongian-class diterpenes 1 and 2 together with two known compounds, chromodorolide B (3) and chromodorolide C (4). Compound 1, named chromodorolide D, is an example of a diterpenoid with a highly rearranged chromodorane carbon skeleton, while compound 2 retains the open side chains. The structures of the new compounds were elucidated on the basis of extensive spectroscopic analysis and chemical conversion. Compounds 1–4 exhibited significant cytotoxicity against NBT-T2 rat bladder epithelial cells.     

Cytotoxic cholic acid type sterones from a marine soft coral <Emphasis Type="Italic">Paraminabea</Emphasis> sp.

Chemical investigation of an Okinawan marine soft coral resulted in the isolation of one new compound (1) and five known cholic acid type keto-steroids 2–6 possessing enone or dienone A-rings and desmosterol (7). The structures of all compounds were elucidated from spectral data, mainly by 1D and 2D NMR techniques, mass spectra, comparison of NMR data with those of reported compounds, and by chemical transformations. Compounds 1–7 showed potent cytotoxic activity.     

Green chemistry & chemical stewardship certificate program: a novel,interdisciplinary approach to green chemistry and environmental health education

ABSTRACT

The Green Chemistry & Chemical Stewardship Certificate Program was designed using the Community of Inquiry (COI) model as a framework for developing curriculum that engages students across the entire program to meet interdisciplinary, professional development program outcomes. The COI framework allows faculty and course developers to develop courses that consider cognitive, social, and teaching presence as equal components of successful learning experiences. In this program, students focus on systems thinking around green chemistry, business, environmental health, chemical alternative assessment tools, and social and environmental justice. They complete a capstone project that identifies a particular environmental or human health issue associated with a chemical and suggest suitable substitutions that are less harmful but equally effective. This paper describes the program’s curriculum, partnerships, delivery modalities, and student feedback as a framework developing professional development opportunities that offer a rich interdisciplinary experience for learners.     

Lanthanoid coordination with a tetrazole-substituted calix[4]diquinone and calix[4]dihydroquinone

The tetrazole-functionalised calixdiquinone 5,17-di-tert-butyl-26,28-bis-(1H-tetrazole-5-ylmethoxy)-calix[4]-25,27-diquinone Q was synthesised by chemical oxidation of the bis-tetrazole calix[4]arene precursor using PbO₂/HClO₄. The single crystal X-ray structure determination of Q confirmed the structure and showed binding of a water molecule in the solid state. Chemical reduction of Q to the dihydroquinone QR was achieved using N,N-diethylhydroxylamine. Comparison of the solution phase photophysical properties of Q or QR in the presence of terbium ions showed significant excitation only with QR, suggesting redox switching of the photophysical response may be possible with this or similar receptor.     

Symposium on the Polymerization of Cyclic Ethers and Sulfides

Abstract

Ring-opening polymerization of cyclic ethers and sulfides has long been exciting broad interest as a distinct area of specialization. Often it was useful to include discussions of these studies as part of other areas such as anionic or cationic polymerization However, these ring-opening polymerizations have likewise been the sole subject of successful symposia The time lapse since the previous such ACS sponsored symposium and the worldwide effort since then amply justified this American Chemical Society sponsored symposium held in Boston, Massachusetts, April 11 and 12, 1972. Judging from its reception, I felt it was a successful. and timely symposium. I think this attests to the considerable amount of good work being done in the area and to the advances that are being made. Not only are there a number of important products on the market based on this chemistry, but also considerable basic chemical knowledge has evolved, leading in turn to still more products.     

Antarctic Environmental Specimen Bank-First 5 Years of Experience

Abstract

The Project on an Antarctic Environmental Specimen Bank (Banca Campioni Ambientali Antartici—BCAA) began in 1994 in order to collect and classify samples from the Antarctic ecosystem to be used for future studies.

The objectives of the project are similar to the general aims of the Environmental Specimen Banks, but they specifically focus on the chemical aspects concerning the research activities of the Italian Project on the “Micropollutants Chemistry” (Sector “Chemical Contamination” of the Italian Antarctic Research Programme—PNRA).

During these first years the facilities suitable for storing a significant number of specimens (now over 2,000) at different temperatures (from ?30°C to ?150°C) and a database system, specifically designed for managing and consulting information concerning both the storage of samples and data on their chemical characterisation, have been developed.

In addition, a programme for validating the procedures of Antarctic organisms storage by checking the stability of some chemical parameters both in fresh and freeze-dried specimens has been developed.     

Diffusion-Controlled Reactions in Polymer Systems

Abstract

Chemical reactions require that at least two molecules or reacting groups come into close proximity so that energy, electrical charge, or chemical groups may be exchanged between them. The process of bimolecular reaction between A and B is given by Eq. (1), taking into account the diffusion step bringing the two reactions in proximity, (AB)