A chiral sensor for arginine and lysine

[structure: see text] We provide access to a new class of C1- or C2-symmetrical host molecules 1 and 2 based on a spirobisindane skeleton. Whereas 1 is selective for short, rigid diamines, 2 prefers longer alpha,omega-dications. Of all the amino acid methyl esters, only those of lysine and arginine with the correct distance between their cationic groups form strong 1:1 complexes in DMSO with 2. NMR titrations reveal high association constants as well as discrimination between the enantiomers of lysine and arginine.