Organoselenium ligands for heterogeneous and nanocatalytic systems: development and applications.

Organoselenium ligands have attracted great attention among researchers during the past two decades. Various homogeneous, heterogeneous and nanocatalytic systems have been designed using such ligands. Although reports on selenium ligated homogeneous catalysts are quite high in number, significant work has also been done on the development of heterogeneous and nanocatalytic systems using organoselenium ligands. A review article, focusing on the utility of organoselenium compounds in the development of catalytic systems, was published in 2012 (A. Kumar, G. K. Rao, F. Saleem and A. K. Singh, Dalton Trans., 2012, 41, 11949). Moreover, it mainly covered the homogeneous catalysts. There are no review articles in the literature on heterogeneous and nanocatalytic systems designed using organoselenium compounds and their applications. Hence, this perspective aims to cover the developments pertaining to the synthetic aspects of such catalytic systems (using organoselenium compounds) and their applications in catalysis of a variety of chemical transformations. Salient features and advantages of organoselenium compounds have also been highlighted to justify the rationale behind their use in catalyst development. Their performance in various chemical transformations [viz. Suzuki-Miyaura coupling, Heck coupling, Sonogashira coupling, O-arylation of phenol, transfer hydrogenation of aldehydes and ketones, aldehyde-alkyne-amine (A3) coupling, hydration of nitriles, conversion of aldehydes to amides, cross-dehydrogenative coupling (CDC), photodegradation of substrates (formic acid, methylene blue), reduction of nitrophenols, electrolysis (hydrogen evolution reaction and oxygen reduction reactions), organocatalysis and dye sensitized solar cells] and relevant aspects of catalytic processes (such as recyclability, substrate scope and green aspects) have been critically analyzed. Future perspectives have also been discussed.