Modern Chemistry (modern + chemistry)

Distribution by Scientific Domains

Selected Abstracts

Dendrimers: a review of their appeal and applications,,

Graham M Dykes
Abstract Dendrimer chemistry is one of the most fascinating and rapidly expanding areas of modern chemistry. This review attempts to uncover the appeal of these structurally-perfect branched macromolecules. The three intriguing regions of a dendritic molecule are discussed: the multifunctional surface, the tailored sanctuary within the branches, and the encapsulated core. The advantages of dendritic structures for property modification, and their potential applications in very diverse areas are illustrated. The exciting merger of dendrimer chemistry with self-assembly offers new, stimulating avenues for exploration. Consequently, self-assembling dendrimers comprise a major section of this article. © 2001 Society of Chemical Industry [source]

On the performance of some aromaticity indices: A critical assessment using a test set

Ferran Feixas
Abstract Aromaticity is a central chemical concept widely used in modern chemistry for the interpretation of molecular structure, stability, reactivity, and magnetic properties of many compounds. As such, its reliable prediction is an important task of computational chemistry. In recent years, many methods to quantify aromaticity based on different physicochemical properties of molecules have been proposed. However, the nonobservable nature of aromaticity makes difficult to assess the performance of the numerous existing indices. In the present work, we introduce a series of fifteen aromaticity tests that can be used to analyze the advantages and drawbacks of a group of aromaticity descriptors. On the basis of the results obtained for a set of ten indicators of aromaticity, we conclude that indices based on the study of electron delocalization in aromatic species are the most accurate among those examined in this work. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008 [source]

Von Seefahrern, Meerschweinchen und Citrusfrüchten.

Der lange Kampf gegen Skorbut
Obwohl der Skorbut die Menschheit von Anbeginn begleitet hat, wurde er erst im 16. Jahrhundert als Krankheit erkannt und es schloss sich eine Jahrhunderte andauernde Aneinanderreihung von kleinen Fortschritten und verpassten Chancen an. Erst zu Beginn des 20. Jahrhunderts identifizierten Wissenschaftler mit Hilfe von Meerschweinchen als Versuchstieren den Skorbut als eine Form von Mangelernährung. Dann begann ein spannender Wettlauf um die Isolierung, Strukturaufklärung und Synthese des Vitamin C. Heute ermöglicht die industrielle Vitamin-C-Synthese eine preiswerte Versorgung von jedermann. Diese Erfolgsgeschichte der modernen Chemie hat dafür gesorgt, dass der Skorbut aus unserem Leben nahezu vollständig verschwunden ist. Although scurvy has been around since the beginning of mankind, it was not until the 16th century that it was recognized as a disease. It took hundreds of years and a long sequence of small advances and missed opportunities to discover its cause. Finally at the beginning of the 20th century and with the help of guinea pigs for testing the experiments, scurvy was identified as a form of malnutrition. This started an exciting race for the isolation, structure determination, and synthesis of vitamin C. As a result, modern industrial synthesis now allows an affordable Vitamin C supply for everyone. This success story due to modern chemistry has made scurvy one of the many diseases that have almost entirely disappeared from our lives. [source]

Ideal für kleine Künstler: Fingerfarben

Klaus Roth Prof.
Fingermalfarben sind Vorzeigeprodukte der modernen Chemie. Die Hauptbestandteile sind Polysaccharide pflanzlichen und halbsynthetischen Ursprungs als Bindemittel, Mineralcarbonate und -oxide als Füllstoffe, Farbpigmente, Farbstoffe und Konservierungsstoffe. Seit 2002 ist die Zusammensetzung nach Europäischem Gesetz geregelt, vor allem, welche Pigmente, Farbstoffe und Konservierungsstoff enthalten sein dürfen. Alle Bestandteile von Fingerfarben gelten als sicher, und die meisten dürfen auch in Kosmetikartikeln und Lebensmitteln verwendet werden. Insgesamt sind Fingermalfarben ein völlig sicheres Produkt in den Händen unserer Kinder. Finger paint is a remarkable product of modern chemistry. The main components are polysaccharides of plant or semi-synthetic origin or non-toxic polyglycols as binders, mineral carbonates, or oxides as fillers, pigments, and/or dyes, and preservatives that delay microbiological spoilage. Since 2002 the composition has been strictly controlled under European Law especially in regard to which pigments, dyes, and preservatives are allowed. All constituents in finger paint can be regarded as safe and most of them are used in cosmetics and as food additives. In summary, finger paint is totally safe in the hands of our children. [source]