Synthesis of cage-type molecules with pi-cavity and selective gas-phase cation complexation.
[structure: see text] Cage-type molecules composed of phenyl walls and caps were synthesized as hosts for the binding of ammonium and alkali metal cations through cation-pi interactions. The synthesis involved a key cyclization step, which was markedly dependent on the capping component. Binding studies by electrospray ionization mass spectrometry toward lithium, sodium, potassium, and ammonium cations showed that the cage-type molecules selectively form a 1:1 complex. A competitive binding study showed that cage 3c (R = Et, R' = OMe) has a preference toward lithium cation while cage 4b (R = Me, R' = OMe) has a similar preference toward both lithium and ammonium ion in the presence of others. This selectivity pattern was tentatively explained by the gate size of the cage-type compounds, not by their cavity size.
Kim
Jeongryul
J
Department of Chemistry and Center for Integrated Molecular Systems, Division of Molecular and Life Sciences, San 31 Hyoja-dong, Pohang 790-784, Republic of Korea.
Kim
Young Kook
YK
Park
Nokyoung
N
Hahn
Jong Hoon
JH
Ahn
Kyo Han
KH