Organoplatinum crystals for gas-triggered switches

Considerable effort is being devoted to the fabrication of nanoscale device s(1). Molecular machines, motors and switches have been made, generally ope rating in solution(2-7), but for most device applications (such as electron ics and opto-electronics), a maximal degree of order and regularity is requ ired(8). Crystalline materials would be excellent systems for these purpose s, as crystals comprise a vast number of self-assembled molecules, with a p erfectly ordered three-dimensional structure(9). In non-porous crystals, ho wever, the molecules are densely packed and any change in them (due, for ex ample, to a reaction) is likely to destroy the crystal and its properties. Here we report the controlled and fully reversible crystalline-state reacti on of gaseous SO2 with nonporous crystalline materials consisting of organo platinum molecules. This process, including repetitive expansion-reduction sequences (on gas uptake and release) of the crystal lattice, modifies the structures of these molecules without affecting their crystallinity. The pr ocess is based on the incorporation of SO2 into the colourless crystals and its subsequent liberation from the orange adducts by reversible bond forma tion and cleavage(10). We therefore expect that these crystalline materials will rnd applications for gas storage devices and as opto-electronic switc hes(11,12).