Pulsed gradient spin-echo (PGSE) diffusion and 1H,19F heteronuclear overhauser spectroscopy (HOESY) NMR methods in inorganic and organometallic chemistry:: Something old and something new

Pulsed gradient spin-echo (PGSE) methodology routinely gives diffusion constants that are accurate to +2%. Generally, the approach is fairly rapid for 1H and 19F and noninvasive and requires only small quantities of material depending on the nucleus chosen. Applications of this methodology include (i) determination of the relative volume of a compound via rH from the Stokes-Einstein equations, (ii) hydrogen bonding, capsules, and host-guest interactions, (iii) ion pairing, and (iv) homogeneous catalysis.