Organic diselenides are nowadays investigated for pharmaceutical applications, as well as in material science in molecular (semi)conductors. In both application's domains, their interactions with Lewis bases, in solution or in the solid state, has been shown to play a crucial role in their biological activity or in their electronic structure. The current comprehensive survey of reported crystal structures of organic diselenides demonstrates the recurrent setting of intermolecular as well as intramolecular chalcogen bonding interactions (ChB) between the selenium atoms acting as ChB donors and Lewis bases. These interactions take place along the two covalent bonds of the selenium atom. In diselenides, stronger interactions are found in the prolongation of the Se−Se bond than in the prolongation of the C−Se bond. Charge activation of ChB is demonstrated in dicationic diselenides or in cation radical salts of 1,2-diselenole derivatives. This survey is extended to the structures of organic selenocyanates whose crystal structures reflect also the presence of two σ-holes, with a much stronger one in the prolongation of the NC−Se bond. Such ChB interactions of selenocyanates with polytopic Lewis bases or with halide anions open novel strategies in crystal engineering and anion recognition strategies.
We report a mild, versatile and high yielding glycosylation method via activation of thioglycoside donors using a Au(iii) catalyst and without using any co-promoter. Both armed and disarmed donors could be activated by this method and the anomeric selectivity could be tuned by changing the solvents.
Activation of a deep electron‐deficient area on chalcogen atoms (Ch=Se, Te) is demonstrated in alkynyl chalcogen derivatives, in the prolongation of the (C≡)C−Ch bond. The solid‐state structures of 1,4‐bis(methylselenoethynyl)perfluorobenzene (1Se) show the formation of recurrent chalcogen‐bonded (ChB) motifs. Association of 1Se and the tellurium analogue 1Te with 4,4′‐bipyridine and with the stronger Lewis base 1,4‐di(4‐pyridyl)piperazine gives 1:1 co‐crystals with 1D extended structures linked by short and directional ChB interactions, comparable to those observed with the corresponding halogen bond (XB) donor, 1,4‐bis(iodoethynyl)‐perfluorobenzene. This “alkynyl” approach for chalcogen activation provides the crystal‐engineering community with efficient, and neutral ChB donors for the elaboration of supramolecular 1D (and potentially 2D or 3D) architectures, with a degree of strength and predictability comparable to that of halogen bonding in iodoacetylene derivatives.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.