the OCH3 configurational effects of M on (M+A)+ adduct ion formation. The findings can be interpreted in terms of multisite electrostatic interaction of oxygens with the cation. Coupled with the results of gas-phase behavior by FABMS/MS(CAD), solution behavior by 1H NMR, and model calculations by MNDO, the characteristic structure of the 1 : 1adduct ion is deduced as host-guest type association between