Detection of hydrogen‐bonded supramolecular complexes using electrospray ionization from chloroform

The stoichiometry of a noncovalent, hydrogen‐bonded supramolecular complex, hub(M) 3 ·RCA 3 , was characterized using electrospray ionization from chloroform. The intact (1:3) complex was observed in the negative‐ion mode as a Cl − ‐bound species using Ph 4 PCl as the source of the charge donor. Collisionally and thermally induced dissociation of the (1:3) complex resulted in the simultaneous loss of all the three RCA units, indicating a cooperative binding of RCA units in the (1:3) complex. These results suggest that the attachment of small, organic‐soluble ions may be a useful technique for mass spectrometric characterization of neutral supramolecular complexes that are stable or soluble only in non‐polar organic solvents.