Shape-selective sorption and fluorescence sensing of aromatics in a flexible network of tetrakis[(4-methylthiophenyl)ethynyl]silane and AgBF 4

The large tetrapod tetxakis[(4-methylthiophenyl)ethynyl]silane was crystallized with AgBF ₄ to form a diamondoid network based on the Ag(I)-thioether interaction. A 4-fold interpenetration of the individual nets was observed, with the rest of the unit-cell volume occupied by the benzene guests. The benzene molecules can be removed without collapsing of the host networks, even though the benzene molecules appear to be well enclathrated in the cavities formed by the host nets. Interestingly, the apohost displays a strict size selectivity for small aromatic molecules, which effectively excludes ortho- and meta-substituted benzene derivatives from entering the pores, enabling, for example, the selective sorption of benzene over hexafluorobenzene. The fluorescence arising from the molecular building block also provides for the sensing of nitrobenzene molecules, which effectively quenches the fluorescence upon entry into the host net. © 2009 American Chemical Society.