Lock and Key Adsorption Chemistry: Preferential Absorption of an Isomer of Di-iodobenzene on Molecular Films of Quinonoid Zwitterions

We have investigated the absorption and adsorption of three isomers of di-iodobenzene on molecular films of a zwitterionic p-benzoquinonemonoimine-type molecule which is characterized by a large intrinsic dipole of 10 D. Specifically, we compared the reversible adsorption and absorption of 1,2-di-iodobenzene, 1,3-di-iodobenzene, and 1,4-di-iodobenzene on molecular films of (6Z)-4-(butylamino)-6-(butyliminio)-3-oxocyclohexa-1,4-dien-1-olate C6H2((center dot center dot center dot) over bar NHR)(2)((center dot center dot center dot) over barO)(2) where R = n-C4H9. We provide unequivocal evidence that molecular adsorption and absorption of 1,3-di-iodobenzene are strongly favored at 150 K over that of the other isomers of di-iodobenzene.