Host–Guest Chemistry in the Gas Phase: Complex Formation of Cucurbit[6]uril with Proton-bound Water Dimer

摘要: The hydration of cucurbit[6]uril (CB[6]) in the gas phase is investigated using electrospray ionization traveling wave ion mobility mass spectrometry (ESI-TWIM-MS). Highly abundant dihydrated and tetrahydrated species diprotonated CB[6] are found ESI-TWIM-MS spectrum. patterns dissociation hydrated indicate that two water molecules bound to each other, forming a dimer complex. Ion studies combined with structures calculated by density functional theory suggest proton-bound present as Zundel-like structure portal, hydrogen bond network carbonyl groups CB[6]. When large guest molecule cannot bind portal. In addition, strong binding energy blocks hindering insertion long alkyl chain into cavity. With small alkali metal cations, such Li+ Na+, single interacts bonds A highly stable or metal-bound at portal suggested an initial process for CB[6], which only dissolved aqueous solution acid ions.