A systematic study of the ternary complex formation process for aromatic amino acids using ucurbit[8]uril (CB[8]) and a viologen amphiphile shows that the affinity of the amino acid needs to be higher or in a comparable range to that of CB[8] for the amphiphile in order to form the ternary complex. Based on these observations, a supramolecular peptide amphiphile and its corresponding vesicle are prepared using a peptide containing an azobenzene moiety. The azobenzene group at the N-terminus of the peptide served as the second guest for CB[8]. The vesicles obtained from this peptide amphiphile show response to a number of external triggers. The trans-cis isomerization of the azobenzene group upon irradiation with UV-light of 365 nm leads to the breakdown of the ternary complex and eventually to the disruption of the vesicle. The deformation-reformation of the vesicle can be controlled by illuminating the disrupted solution with light of 420 nm as it facilitates the cis-trans isomerization. Thus, the vesicle showed a controlled and reversible response to UV-light with the ability for manipulation of the formation-deformation of the vesicle by the choice of an appropriate wavelength. The vesicle showed response to a stronger guest (1-adamantylamine) for CB[8], which displaces both the guests from the CB[8] cavity and consequently ruptures the vesicle structure. 2,6-Dihydroxynaphthalene acts as a competitive guest and thereby behaves as another external trigger for replacing the peptide from the CB[8] cavity by self-inclusion to form the ternary complex. Henceforth, it allows retaining the vesicle structure and results in the release of the peptide from the vesicle.

A systematic study on the cucurbit[8]uril (CB[8]) assisted transformation of a mixed micellar system of CTAB and a viologen surfactant to vesicles is depicted. The micelle to vesicle transformation is assisted by a charge transfer complex mediated ternary complexation between the viologen group of the surfactant, CB[8], and 2,6-dihydroxynaphthalene. In the presence of CB[8], both the surfactants formed U-shaped binary inclusion complexes inside the CB[8] cavity, and no selective binding is observed. Upon addition of DHN, CB[8] showed two different self-sorting mechanisms. The U-shaped binary complex with CTAB breaks down, and CB[8] moves toward the viologen headgroup of the other surfactant to form a stable ternary complex. In the case of the viologen surfactant, CB[8] moved toward the headgroup leaving the hydrophobic tail free in order to form the ternary complex. The mechanistic detail of this micelle to vesicle transformation is revealed through methodical studies using (1)H and DOSY NMR, ESI-MS, ITC, and other instrumental techniques.

A new organocatalytic glycosylation method exploiting the lactol functionality has been disclosed. The catalytic generation of glycosyl oxacarbenium ions from lactols under forcible conditions via weakly Brønsted-acidic, readily available secondary amine salts affects the diastereoselective glycosylation of 2-deoxypyranoses and furanoses. This operationally simple iminium catalyzed activation of 2-deoxy hemi-acetals is a potential alternative to the existing cumbersome methods that need specialized handling. The mechanisms for this unique transformation and kinetic/thermodynamic effects have been discussed based on both experimental evidence and theoretical studies.

We demonstrate here that the strained and bulky protonated 2,4,6-tri-tert-butylpyridine salts serve as efficient catalysts for highly stereoselective glycosylations of various glycals. Moreover, the mechanism of action involves an interesting single hydrogen bond mediated protonation of glycals and not via the generally conceived Brønsted acid pathway. The counteranions also play a role in the outcome of the reaction.

The reaction of secondary amine salts with 2‐deoxy‐ribofuranoses under forcible conditions leads to the putative furanosyl oxocarbenium ion that is trapped with various alcohols to provide 2‐deoxy‐ribofuranosides. The observed anomeric selectivities range from an equimolar mixture to complete α‐selectivity in the case of bulky sugar acceptors. Owing to the mechanism and temperature of the transformation, the generated oxocarbenium ion shows little or no facial preference towards the nucleophilic attack of non‐carbohydrate acceptors and leads to a mixture of anomers in the case of benzyl and acetyl protected donors. However, the conformationally less flexible tetraisopropylsilyl protected donor reacted with both sugar and non‐sugar acceptors in a stereoselective fashion. Besides, the glycosylation with 2‐cyanoethanol gave the product with unexpected beta‐selectivity presumably due to nitrile effect. The operationally simple organocatalytic protocol provides easy access to otherwise difficult 2‐deoxy‐ribofuranosides/disaccharides.