Selective retention of methanol over ethanol by a cyclen-based cryptand/copper(II) complex.

A cyclen-based cryptand (2) was prepared in a two-step synthesis from dioxocyclen. When a Cu(CF3SO3)2 complex with 2 was prepared in methanol, the 2/Cu(CF3SO3)2 complex incorporated one methanol in the cavity formed by the diethyleneoxy unit and the NH group of the cyclen. When prepared in ethanol, the 2/Cu(CF3SO3)2 complex similarly incorporated one ethanol. Cold electrospray ionization mass spectrometry (CSI-MS) of the 2/Cu(CF3SO3)2/alcohol complexes selectively retains methanol over ethanol under CSI-MS conditions.