An Efficient Ionization Method of Electrospray Mass Spectrometry: The Development of an Aromatic‐Cored Matrix That Wraps Labile Metal Complexes through Molecular Recognition

Compound 1 a , which possesses a triphenylene core and six tetraethyleneoxide side chains, shows efficient ionization of M II ‐containing (M=Pd, Pt) complexes in electrospray ionization mass spectrometry (ESI‐MS). The molecular ion peaks [ M ] + , which are hardly detected under common ESI‐MS conditions, are clearly observed as their [ M ⋅( 1 a ) n ] + ( n =1–4) adducts. UV‐visible and NMR studies reveal that the electron‐rich triphenylene core of 1 a binds to the electron‐deficient frameworks of the M II complexes in solution, giving rise to charge transfer (CT) complexes. We suggest that 1 a stabilizes the complexes and promotes efficient ionization through unique donor–acceptor molecular recognition.