. H NMR spectra of the host-guest titration of PA [6] with guest 1, increasing the guest concentration according to Table The peak broadening indicates a very strong binding between the host and guest 3, restricting the molecular movement of the host and leading to a short t2 transverse relaxation time, which causes peak broadening. Upon heating the sample, the molecular movement increases, which enhances the transverse relaxation time t2, followed by peak sharpening.