Computational and ion mobility MS study of (all-S)-cyclohexylhemicucurbit[6]uril structure and complexes

Abstract

A computational study of (all-S)-cyclohexylhemicucurbit[6]uril and its complexes with anions (Cl(-), Br(-), I(-) and HCOO(-)), the proton (H(+)) and non-dissociated acid (HCl, HBr, HI and HCOOH) guests was performed. The geometries of guest-host complexes were optimized via density functional theory using the BP86 functional, SV(P) basis set and Stuttgart pseudopotentials for iodide. Binding affinities and their trends were evaluated at the BP86/TZVPD level of theory. In addition, the quantum theory of atoms in molecules was used to gain insight into guest-host interactions. A computational study in the gas phase and ion-mobility mass-spectrometry analysis revealed that the studied macrocycle formed inclusion complexes with anions. Protonation of the macrocycle is preferred at the nitrogen atom pointing inside of the cavity. In the studied conditions, non-dissociated acids formed complexes at the oxygen atom pointing outside of the macrocycle.

Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution

“…S2 and S3†). Halide anions (13 to 35 Å 3 in volume 36 ), while readily forming complexes with 6-membered hemicucurbiturils, 37–41 appear to have very low affinity towards cycHC[8] , presumably due to a mismatch in size with the cavity of cycHC[8] . As expected, the affinity towards more heavily solvated anions was found to be lower than for weakly solvated ones.…”

Hemicucurbit[n]urils and Their Derivatives – Synthesis and Applications

“…Gas phase calculationson on the (all-S)-cychmCB [6] indicated that the anions were located inside the cavity and the affinity of the anions (in gas phase) is Cl À > Br À > HCOO À > I À . [28] The existence of even larger macrocycles of cyclohexylhemicucurbit[n]uril (n = 7-10) were first shown in 2014 by analysing the reaction mixture of (all-R)-cychmCB [6] by HPLC-MS. [29] The (all-R)-cyclohexylhemicucurbit [8]uril (all-R-cychmCB [8]) was isolated in 11 % yield. The chloride and formate complexes of (all-R)-cychmCB [8] were detected in negativemode MS.…”

Templating Effects in the Dynamic Chemistry of Cucurbiturils and Hemicucurbiturils

“…Rapid equilibration between library members under controlled conditions is necessary, making imines, [16] hydrazones [17] (Scheme 2, A, B), disulphides [18] and boronates [19] currently the most applied linkers. [34] Computational and ionmobility MS study of cycHC [6] [35] in gas phase demonstrates that the favourable site for protonation of (S,S)-cycHC [6] was at a N-atom on the inside of the cavity (Figure 1, left side). the monomer and alkylthiourea is carried along as substituent of the resulting HC (Scheme 3, C).…”

“…According to theoretical study in presence of water, the formation of the second CÀN bond and deprotonation is mediated by water and the urea C= O group (Scheme 3, A). [35] that the protonation site may depend on proton carrier and media. Therefore this dynamic multicomponent chemistry (Scheme 2 C) has been utilized in chiral sensing.…”

“…[15] BU figures are based on the crystal structures CCDC 809240 and 809242 from ref. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 form inclusion complexes with halides [35] and (R,R)-cycHC [8] to form anion inclusion complexes size selectively with larger anions. [72] and CCDC 1053111 from ref.…”