Designing Synthetic Cationic Molecular Receptors for Alcohols

The monoprotonation of diaza-12-crown-6 derivatives converts these macrocycles to hosts for short-chain alcohols; the association constant Ka is as high as 47 M−1. For the neutral diaza crown ether, on the other hand, Ka is only 1.1 M−1. X-ray structure investigations show that the alcohol (R = Me) is held in place by two hydrogen bonds (see right). R = Me, Et, nPr, nBu; R′ = PhCH2, PhCH2CH2