title: Unusual complex formation and chemical reaction of haloacetate anion on the exterior surface of cucurbit[6]uril in the gas phase.
abstract: Noncovalent interactions of cucurbit[6]uril (CB[6]) with haloacetate and halide anions are investigated in the gas phase using electrospray ionization ion mobility mass spectrometry. Strong noncovalent interactions of monoiodoacetate, monobromoacetate, monochloroacetate, dichloroacetate, and trichloroacetate on the exterior surface of CB[6] are observed in the negative mode electrospray ionization mass spectra. The strong binding energy of the complex allows intramolecular S(N)2 reaction of haloacetate, which yields externally bound CB[6]-halide complex, by collisional activation. Utilizing ion mobility technique, structures of exteriorly bound CB[6] complexes of haloacetate and halide anions are confirmed. Theoretically determined low energy structures using density functional theory (DFT) further support results from ion mobility studies. The DFT calculation reveals that the binding energy and conformation of haloacetate on the CB[6] surface affect the efficiency of the intramolecular S(N)2 reaction of haloacetate, which correlate well with the experimental observation.
authors.affiliation: Department of Chemistry, Pohang University of Science and Technology, Gyeongbuk, Korea.
authors.forename: Tae Su
authors.initials: TS
authors.lastname: Choi
authors.forename: Jae Yoon
authors.initials: JY
authors.lastname: Ko
authors.forename: Sung Woo
authors.initials: SW
authors.lastname: Heo
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Ko
authors.forename: Kimoon
authors.initials: K
authors.lastname: Kim
authors.forename: Hugh I
authors.initials: HI
authors.lastname: Kim
mesh_terms: D001952:Bridged-Ring Compounds / Q000737:chemistry*; D062845:Chloroacetates / Q000737:chemistry*; D003198:Computer Simulation; D005740:Gases / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D008958:Models, Molecular; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D001952:Bridged-Ring Compounds; D062845:Chloroacetates; D005740:Gases; D007093:Imidazoles; C454805:cucurbit(6)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils