Current Organic Chemistry - Volume 11, Issue 6, 2007

In the paper the introduction pointing out the important role of viologens is followed by two chapters concerning rotaxanes with a thread incorporating viologens, and those with a ring built from viologens. In the next two chapters dendrimers containing viologens as a core and those with viologens localized in their apical positions are presented. The fifth chapter deals with cucurbiturils and calixarenes noncovalently bonding viologen units. The final chapter shows other viologen containing compounds; it mainly concerns assemblies of their nanostructured films.

Antisense strategy represents a promising molecular tool for efficient and selective chemotherapeutic action. It belongs among oligonucleotide strategies that employ specific single-stranded sequences of deoxyribo- and ribonucleotides or their synthetic analogs to block or suppress expression of a pathogen in its early stage. This approach is also promising for studies of the biological function of the gene. However, the routine use of modified oligonucleotides in practice is complicated by non-ideal properties of currently available oligonucleotide analogs. A successful medical treatment requires not only proper binding of the modified oligonucleotide to its cellular target but also its efficient cellular uptake, stability and appropriate distribution in the intracellular environment. The latter processes can be effectively studied by various microfluorescence techniques. The paper reviews the current situation in the application of advanced microfluorescence methods in this field and gives a brief description of the oligonucleotide strategy and possibilities to support the cellular uptake, theoretical and technical basics of current fluorescence microimaging and fluorescence microspectroscopy including time-resolved measurements. Second part of the paper describes experiment preparation, surveys the most interesting studies published so far and outlines the perspectives.

Analytical methods often benefit from progress in other fields of science. One of the best-illustrated and most spectacular examples is NMR technology and its numerous improvements that have resulted from new applications in biology and medicine. These techniques came under the term MRI during the mid 1970s, and then in vivo MRS since the early 1980s. Biomedical NMR of lipids is presently emerging as an exciting topic in onco-biology. However, for various reasons, biochemists up to quite recently showed more interest in proteins than in lipids. This is probably because proteins are “active” reactant molecules and lipids are often still considered as merely nutritional or structurally more “passive” components. While classical biochemistry quantifies molecules independently from each other, biophysical methods, including NMR, also take into account the multi-molecular structure and the resulting “visibility” of each component, which is itself related to mobility. Results from numerous studies concerning lipids in cancer mainly focused on blood plasma using high resolution in vitro NMR, cells using both classical high resolution ex-vivo NMR and high-resolution Magic Angle Spinning NMR and, more recently, in vivo tumours by single-voxel spectroscopy or by Chemical Shift Imaging.

Its outstanding ability to generate singlet oxygen or reactive oxygen species upon irradiation with light makes hypericin one of the most powerful photosensitizers to be found in nature. The most important fields of application of hypericin seem presently to be its use as a photosensitizing anti-viral agent to destroy virus particles in blood preparations, to sensitize the destruction of superficial tumors, and its use as a diagnostic tool for fluorescence detection of malignant tissue. Despite of all of its benefits and its strong photosensitizing ability, the application of hypericin in photodynamic therapy (PDT) suffers from three main disadvantages: cost expensive isolation, limited solubility under physiological conditions, long wavelength absorption maximum outside the optimum wavelength range for a photosensitizer. Thus, over the last decade several efforts have been undertaken to synthesize new hypericin derivatives with increased solubility, bathochromically shifted long wavelength absorption band, enhanced photosensitizing potential, and applicability in a more widespread field (second generation hypericin based photosensitizers). The objective of this review is to discuss the investigations undertaken in the development of second generation hypericin based photosensitizers. The focus will be on the synthesis aspects of such derivatives as well as on their photochemical properties, their advantages, and disadvantages. Several of these novel synthetic hypericin derivatives have already been tested in vitro and/or in vivo. Accordingly, also a summary of the corresponding results will be presented.

Recently, the concept of fluorous bi-phasic catalysis (FBC) was introduced as an environmentally benign recyclable process. Numerous nine and long-enough (e.g. perfluorooctyl, C8F17) fluorous ponytails can be employed for fluorous phase immobilization of lanthanide catalysts and to catalyze the Diels-Alder and Friedel-Crafts reactions more efficiently. Meanwhile, Bis(perfluoroalkylsulfonyl)amides of lanthanum, ytterbium, yttrium, and scandium have been described as strong Lewis acids, more powerful catalysts for Diels-Alder acylation, esterification, and Baeyer-Villiger reactions. The key to success is that lanthanide complexes are extremely efficient Lewis acid catalysts by virtue of the highly electron-withdrawing and solubilizing effect of tris(perfluoroalkylsulfonyl)methide and bis(perfluoroalkylsulfonyl)amide without hydrocarbon spacers. On the other hand, it has been reported that a new rare earth perfluorocarboxylate catalyst, the rare earth perfluorooctanoate, showed efficient catalytic activity in the Mannich reaction and the reaction of indole with carbonyl compounds due to the unique surfactivity of the long perfluoro-chain. These catalysts can be prepared, stored and recoveredeasily. In this paper, we will review the application of long perfluoro-chain lanthanide catalysts in a series of organic reactions.