A chiral sensor for arginine and lysine

[GRAPHICS] We provide access to a new class of C-1- or C-2-symmetrical host molecules 1 and 2 based on a spirobisindane skeleton, Whereas 1 is selective for shor t, rigid diamines, 2 prefers longer alpha,omega-dications. Of all the amino acid methyl esters, only those of lysine and arginine with the correct dis tance between their cationic groups form strong 1:1 complexes in DMSO with 2, NMR titrations reveal high association constants as well as discriminati on between the enantiomers of lysine and arginine.