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The versatility of hyaluronic acid is connected to not only its size, but also to inherent opportunities within the molecule for multiple bonds and for the differentiated release of bound functional molecules. Here, ester bonds are used to introduce substitutes for the material's alcohol groups, thus providing elasticizing, moisturizing and antiaging benefits for skin care. [ABSTRACT FROM AUTHOR]

Terdentate ruthenium(II) complexes of general formula RuX(CNN)(dppb) (X chloride, hydride, alkoxide; dppb Ph2P(CH2)4PPh2), where CNN is a deprotonated 2-aminomethyl-6-arylpyridine ligand, have been prepared. The orthometalated derivative RuCl(b)(dppb) (1) has been obtained by reaction of RuCl2(PPh3)(dppb) with N,N-dimethyl-2-aminomethyl-6-(4-methylphenyl)pyridine (Hb) in 2-propanol and in the presence of triethylamine by elimination of PPh3and HCl. Similarly, RuCl(a)(dppb) (2) and the chiral analogue RuCl(c)(dppb) (3), containing primary amine ligands, have been isolated starting from 2-aminomethyl-6-(4-methylphenyl)pyridine (Ha) and (R)-2,2-dimethyl-1-(6-phenylpyridin-2-yl)propylamine (Hc), respectively. The synthesis of the functionalized pyridines Ha−Hcis here described, whereas the crystal structure of 3has been determined through an X-ray diffraction experiment. Treatment of 1−3with sodium or potassium isopropoxide gives the corresponding hydrides RuH(b)(dppb) (4), RuH(a)(dppb) (5), and RuH(c)(dppb) (6) from the ruthenium isopropoxide complexes, via a -H elimination process. Studies in solution show that the isopropoxides bearing a NH donor group are in equilibrium with the corresponding hydrides (5 and 6). Reaction of 5with benzophenone leads to the alkoxide Ru(OCHPh2)(a)(dppb) (7), which has been proven to interact with benzhydrol in C6D6, leading to the adduct 7·(HOCHPh2), the alkoxide ligand, and the alcohol being in rapid exchange. Complexes 2 and3display a remarkable high catalytic activity for the transfer hydrogenation of ketones to alcohol in 2-propanol using a very small amount of catalyst. With the chiral complex 3(0.005 mol %) methyl-aryl ketones can be quickly reduced (TOF ranging from 5.4 × 105to 1.4 × 106h-1) with an enatiomeric excess up to 88%.

Recent successful applications of NMR spectroscopy and imaging in food science prompted the authors to use these new techniques for the analysis of espresso coffee. The target of this work was to identify an experimental procedure to obtain maximum information from high-resolution ¹H spectra. Only the espresso coffee was considered as the true food, since it includes all aromatic substances responsible for the coffee aroma and taste. A big effort was made in order to select an easy, quick and non-degrading procedure to analyse the espresso cup content, preventing artificial or natural degradation effects with a particular care in the measurement of labile and volatile components. The procedure was tested on two arabica and one robusta samples; each sample was prepared with three roasting degrees to follow the chemical changes due to the roasting process. Moreover, one water extract was prepared also from ground green coffees. As a comparison, each coffee extract was prepared both with a standard ‘espresso coffee machine’ and with a ‘mocha’ as used in the domestic setting. Significant differences among the three samples were observed. Moreover, for all samples, as a function of the roasting degree, a clear trend in the chemical composition was observed. © 1999 Society of Chemical Industry

Crude lipid extracts from different tissues were analysed by ³¹P NMR spectroscopy in a mixture of triethylamine, dimethylformamide and guanidinium chloride. Higher dispersion of the ³¹P NMR signals and better reproducibility of the chemical shifts were achieved with respect to the spectra acquired in the conventional chloroform–methanol–water solvent. In particular, the reproducibility of the chemical shifts allowed the unambiguous identification of all the components in the ³¹P NMR spectra of complex phospholipid mixtures, which was not feasible using the chloroform–methanol–water system. The efficiency of the new solvent was tested on crude lipid extracts from different biological sources such as lecithin, mouse mammary carcinoma, porcine stomach, porcine spleen, porcine brain, human red blood cells, yeast, fungi and tuna fish muscle. The reproducibility of the chemical shift of the phospholipid signals was demonstrated in the presence of various amounts of neutral lipids (triglycerides) and sterols, which are commonly present in the Folch extracts. © 1998 John Wiley & Sons, Ltd.