A potentiometric and NMR investigation of triphosphate recognition by linear and bismacrocyclic octaamines possessing a 1,4-xylenyl linker

The host-guest binding interaction between two symmetrical octaazaligands, the para-xylenylbiscyclam and its linear analogue, the para-xylenylbis-1,4,8,11-tetraazaundecane, and triphosphate anion is reported. The results clearly indicate that the linear octaamine presents a better triphosphate recognition in the whole p[H] range than its biscyclam analogue. The polyprotonated octaamine is sufficiently flexible to wrap itself round the anion in a way to achieve an optimal fit for the best host-guest recognition.