The organoselenium and organotellurium compounds have been described as promising pharmacological agents in view of their unique biological properties. Glutathione peroxidase mimic, antioxidant activity and thioredoxin reductase inhibition are some of the properties reviewed here. On the other hand, little is known about the molecular toxicological effects of organoselenium and organotellurium compounds. Most of our knowledge arose from research on inorganic selenium and tellurium. However, the ability to oxidize sulfhydryl groups from biological molecules can be involved both in their pharmacological properties and in their toxicological effects. In fact, exposition to high doses of organoselenium or to low doses of organotellurium causes the depletion of endogenous reduced glutathione in a variety of tissues. Thus, the design of compounds that cause low depletion of glutathione and react with specific targeted proteins, controlling specific metabolic pathways, will represent an important progress in understanding the field of organochalcogen compounds. Furthermore, the development of new organochalcogens with higher thiol-peroxidase activity that can use other non-toxic thiol reducing agents, such as N-acetylcysteine instead of glutathione, will permit the investigation of the co-administration of organochalcogens and thiols as a formulation for antioxidant therapy.

Organoselenium and Organotellurium Compounds: Toxicology and Pharmacology

Chemistry of biologically important synthetic organoselenium compounds.

Enzyme-like catalysis by molecularly imprinted polymers.

This review describes a multidimensional treatment of molecular recognition phenomena involving aromatic rings in chemical and biological systems. It summarizes new results reported since the appearance of an earlier review in 2003 in host-guest chemistry, biological affinity assays and biostructural analysis, data base mining in the Cambridge Structural Database (CSD) and the Protein Data Bank (PDB), and advanced computational studies. Topics addressed are arene-arene, perfluoroarene-arene, S⋅⋅⋅aromatic, cation-π, and anion-π interactions, as well as hydrogen bonding to π systems. The generated knowledge benefits, in particular, structure-based hit-to-lead development and lead optimization both in the pharmaceutical and in the crop protection industry. It equally facilitates the development of new advanced materials and supramolecular systems, and should inspire further utilization of interactions with aromatic rings to control the stereochemical outcome of synthetic transformations.

Aromatic rings in chemical and biological recognition: energetics and structures.

Tetrahedron report number 221

Selenium stabilized carbanions. Acidity of allyl and vinyl sulfides and selenides

Structure of Silyl‐Substituted Allenyl/Propargyllithium Reagents in Solution

Interconversion of contact and separated ion pairs in silyl- and arylthio-substituted alkyllithium reagents.

Palladium(II) acetate (1) and two new complexes of the ligand α,α,α′,α′-tetramethyl-1,3-benzenedipropionate (esp2–), Cs-Pd3(esp)3 (Cs-2) and C3h-Pd3(esp)3 (C3h-2), are studied in the solid state and in solution. Variable-temperature NMR and DFT studies of Cs-2 reveal an unusual shielding region above the Pd atoms. The compounds show a surprising quasi-reversible reduction between −880 and −1200 mV versus Fc/Fc+, and the Pd3(esp)3 complexes may be cleanly reduced electrochemically. EPR spectra of reduced samples show pseudo-axial signals with 105Pd hyperfine coupling, consistent with unprecedented, isostructural Pd35+ species with a valence-trapped PdII–PdII–PdI electronic structure.

Hans J. Reich

Papers

Selenium stabilized carbanions. Acidity of allyl and vinyl sulfides and selenides

Structure of Silyl‐Substituted Allenyl/Propargyllithium Reagents in Solution

Interconversion of contact and separated ion pairs in silyl- and arylthio-substituted alkyllithium reagents.

Palladium Acetate Revisited: Unusual Ring-Current Effects, One-Electron Reduction, and Metal-Metal Bonding.

Organoselenium chemistry. Intra- and intermolecular trapping of selenenic acids formed by selenoxide elimination. Formation of a selenium ylide