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Journal ArticleDOI

Understanding behaviour of vitamin-C guest binding with the cucurbit[6]uril host

04 May 2017-Supramolecular Chemistry (Taylor & Francis)-Vol. 29, Iss: 5, pp 387-394
TL;DR: In this paper, non-covalent interaction and complexation behavior of sodium ascorbate (SA) with cucurbit[6]uril (CB[6]) at neutral pH in aqueous Na2SO4 solution was investigated using various analytical techniques like NMR, UV-Vis, fluorescence, TGA and DRS.
Abstract: The present study describes non-covalent interaction and complexation behaviour of sodium ascorbate (SA) with cucurbit[6]uril (CB[6]) at neutral pH in aqueous Na2SO4 solution. The interaction behaviour is investigated using various analytical techniques like NMR, UV–Vis, fluorescence, TGA and DRS. The substantial increase in the intensity of emission and absorption spectra of sodium ascorbate is observed. The Benesi–Hildebrand evaluation method is used to determine the stoichiometry and equilibrium constant of the cucurbit[6]uril–sodium ascorbate complex, which suggested the 1:1 complex. Time-dependent 1H NMR, 13C CP MAS and CD studies also echoed non-covalent interaction between SA with CB[6].
Citations
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Journal ArticleDOI
TL;DR: In this article, a review provides an overview of related advances and achievements involving such a combination of Q[n]-based host-guest chemistry and Q[ n]-based coordination chemistry.
Abstract: Cucurbit[n]urils (Q[n]s), a relatively new class of macrocyclic hosts with a rigid hydrophobic cavity and two identical carbonyl-fringed portals, have attracted much attention since the first member of the Q[n]-family, cucurbit[6]uril (Q[6]), was structurally identified in 1981 by Mock and co-workers. The interactions of the rigid cavities and negative portals of Q[n]s have resulted in the development of two almost mutually exclusive areas of study, namely Q[n]-based host–guest chemistry and Q[n]-based coordination chemistry. However, researches has revealed that Q[n]-based host–guest inclusion interactions may be influenced by metal ion coordination at the Q[n] portals, and in turn, coordination of metal ions at the Q[n] portals could be promoted by the formation of Q[n]-based inclusion host–guest complexes. Thus, this review provides an overview of related advances and achievements involving such a combination of Q[n]-based host–guest chemistry and Q[n]-based coordination chemistry, which could become an emerging branch, that is, Q[n]-based host–guest-metal ion chemistry. In particular, it could be useful in the treatment of wastewater, kinetic studies, drug delivery, the construction of novel supramolecular frameworks, metal-catalyzed reactions, recognition or response to metal cations, and so on.

22 citations


Cites background from "Understanding behaviour of vitamin-..."

  • ...Significant increases in the intensities of the emission and absorption spectra of SA were observed, probably due to its restricted motion in the cavity of Q[6] by the coordinated Na+ cation [86]....

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Journal ArticleDOI
05 Apr 2018-Symmetry
TL;DR: This review will present examples from three directions of induction of chirality in or by cucurbituril-type hosts: first, through the incorporation of stereogenic elements into host molecules; second, through complexation with achiral guests, which leads to axial supramolecular chiralities and helical structures; and third,Through the formation of complexes with chiral guests in multi-molecule complexes and induction of supramolescular chorality.
Abstract: Cucurbituril-type hosts are highly symmetric, but there are means to break their symmetry. This review will present examples from three directions of induction of chirality in or by cucurbituril-type hosts: first, through the incorporation of stereogenic elements into host molecules; second, through complexation with achiral guests, which leads to axial supramolecular chirality and helical structures; third, through the formation of complexes with chiral guests in multi-molecule complexes and induction of supramolecular chirality. In addition, a list of chiral guests used in binding studies with cucurbiturils is collected. We would envision that encouraged by the outlined examples of outstanding applications of chiral cucurbituril-supramolecular systems, the boundaries of chiral applications of cucurbiturils would be widened.

12 citations


Cites background from "Understanding behaviour of vitamin-..."

  • ...[82] [83] [84] G Symmetry 2018, 10, x FOR PEER REVIEW 18 of 26 CB[7] CB[6] Ref....

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Journal ArticleDOI
TL;DR: In this article, the potential of cucurbit[5]uril to be used as inverse phase transfer catalyst in electrocatalytic hydrogenation of α,β-unsaturated ketones is illustrated.
Abstract: The potential of cucurbit[5]uril to be used as inverse phase transfer catalyst in electrocatalytic hydrogenation of α,β-unsaturated ketones is illustrated. The interaction behavior among isophorone and cucurbit[5]uril was also investigated using cyclic voltammetry and UV/vis absorption spectroscopy. The results concerning to both techniques revealed an enhancement in the intensity of the absorption peak and also in the current cathodic peak of isophorone in presence of cucurbit[5]uril. This achievement is related to the increase of the isophorone solubility in the medium being an indicative of a host-guest complex formation. The electrochemical hydrogenation of isophorone using cucurbit[5]uril was more efficient than others well-stablish methodologies. Regarding to (R)-(+)-pulegone and (S)-(+)-carvone, the use of cucurbit[5]uril leads to an increase of 17% and 9%, on average, respectively, in the yields when compared to the control reaction. The efficiency of selective C=O bond hydrogenation of 1-acetyl-1-cyclohexene was evaluated. The presence of cucurbit[5]uril increased by 12% the hydrogenations yields of 1-acetyl-1-cyclohexene when compared to the control reaction. In this sense, these results open up an opportunity to carry out electrocatalytic reactions within the cucurbit[5]uril environment.

1 citations

Journal ArticleDOI
TL;DR: Theoretical methods were used to investigate the encapsulation of two vitamin E isoforms into the macrocycle cucurbit[7]uril (CB[7]). The [email protected][7] complexes were stable along 100 ns molecular dynamics simulation with similar conformation as mentioned in this paper .
Abstract: Theoretical methods were used to investigate the encapsulation of two vitamin E isoforms, α-tocopherol (α-TOC) and α-tocotrienol (α-TCT), into the macrocycle cucurbit[7]uril (CB[7]). The [email protected][7] complexes were stable along 100 ns molecular dynamics simulation with similar conformation. The binding free energy obtained from the MM/PBSA method is ∼ –25 kcal.mol−1 for both complexes. Also, DFT-D3/B3LYP/6-31G(d,p) calculations indicate a favorable encapsulation process with bind energies of –58.25 (α[email protected][7]) and –61.08 kcal.mol−1 (α[email protected][7]). Moreover, the calculated solvation enthalpies show a solubility enhancement of complexed vitamins compared to their free forms. Finally, CB[7] may be a promising macrocyclic host for encapsulating vitamins E.
References
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Journal ArticleDOI
TL;DR: This review brings together the past and current methods for synthesizing the classical cucurbit[n]uril (Q[n], structural variants, and derivatives, and particular attention is drawn to the synthesis of structural variants that have significance for chiral recognition properties.

29 citations

Journal ArticleDOI
TL;DR: This review first discussed some reduction potential-based biochemical activities of vitamin C such as assisting the post-translational collagen modification as well as acting as an antioxidant and pro-oxidant that may contribute to the adverse effect of high-level vitamin C supplementation in clinical trials.
Abstract: Scurvy due to severe vitamin C (ascorbic acid) deficiency among sailors was one of the earliest documented occupational diseases. This review first discussed some reduction potential-based biochemical activities of vitamin C such as assisting the post-translational collagen modification as well as acting as an antioxidant and pro-oxidant. These known activities of vitamin C were then used to address recent outcomes of vitamin C clinical trials on the prevention and treatment of non-scurvy diseases such as cardiovascular diseases and cancer. The pro-oxidant activity may contribute to the adverse effect of high-level vitamin C supplementation in clinical trials.

11 citations