Binding molecular entity with selectivity

The requisite research issues essential to the creation of fluorescent chemosensors are (1) how can one bind a molecular entity with selectivity (preferably from water), (2) what molecular changes result in fluorescence changes, and (3) what mechanisms for binding and fluorescence signal transduction intersect. 

Binding a Molecular Entity with Selectivity. While much of organic chemistry focusses on the selective creation of covalent bonds, such irreversible associations of potential analytes yield chemodosimeters (designed for cumulative assay) in contrast to chemosensors (designed for real-time assay). Thus, sensing applications require the existence of receptors (hosts) that associate with analytes (guests) selectively and reversibly. 

Second, since the small number of atoms bind firmly to the underlying support, it may be more appropriate to regard the nanocluster as a molecular entity with its activity and selectivity being more like that of multinuclear single-site catalysts, such as that found in many metalloenzymes, e.g., hydrogenases, than of a bulk metal or alloy. 

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