A molecular-level plug/socket system: Electronic energy transfer from a binaphthyl unit incorporated into a crown ether to an anthracenyl unit linkedto an ammonium ion

The reversible acid/base- (hydrogen-bonding-) controlled association betwee n racemic crown ethers incorporating a binaphthyl unit (the socket) and wir elike compounds bearing an anthracenyl unit (the plug) is described. The co mpounds used were the (+/-)binaphthocrown ethers BN20C6, BN23C7, and BN26C8 , the amines 9-methyl(aminomethyl)anthracene (AM) and 9-methyl(aminobenzyl) anthracene (AB), and their hexafluorophosphate salts AMH(+)PF(6)(-) and ABH (+)PF(6)(-). The experiments were carried out in CH,CI, solution. Fluoresce nce data, H-1 NMR spectra, and molecular modeling all point to the formatio n of stable, pseudorotaxane-type H-bonded adducts of BN23C7 with AMH(+) and of BN26C8 with AMH+ and ABH(+). These systems can be considered as molecul ar-level plug/socket devices since they are characterized by i) reversible, acid/base-controlled plug in/plug out behavior and ii) photoinduced flow o f electronic energy from the binaphthyl to the anthracenyl unit in the plug in state. The above concepts can be easily extended to systems in which a) the plug in/plug out function is stereoselective and b) light excitation i nduces an electron flow instead of a flow of electronic energy.