Modulation of redox reactivity of resazurin through host-guest complexation with Cucurbit[]uril ( = 7, 8).

Resazurin (Alamar Blue, RZ) is a widely utilized fluorescent probe for biological sensing, whose fluorescent intensity can be modulated by changing its redox states; thereby, electrochemical reactivity of RZ is of significance when designing a sensing assay. Herein, we report novel two-way electrochemical reactivity modulation of RZ using host-guest complexation with rigid molecular containers cucurbit[]uril (CB, = 7, 8). The complexation between CB and RZ is confirmed by H NMR measurements and supported by computational simulation, and the binding constants are determined via UV-vis titration.

Noncovalent Modulation of Chemoselectivity in the Gas Phase Leads to a Switchover in Reaction Type from Heterolytic to Homolytic to Electrocyclic Cleavage.

In the gas phase, thermal activation of supramolecular assemblies such as host-guest complexes leads commonly to noncovalent dissociation into the individual components. Chemical reactions, for example of encapsulated guest molecules, are only found in exceptional cases. As observed by mass spectrometry, when 1-amino-methyl-2,3-diazabicyclo[2.

Modulating the reaction pathway of phenyl diazonium ions using host-guest complexation with cucurbit[7]uril.

Aryl diazonium ions are known to be an important intermediate in the divergent synthesis of azo compounds and substituted aromatics. The presence of more than one electrophilic center in a diazonium ion could lead to undesirable side reactions during a synthesis. Herein, we report that the electrophilic α-carbon on a phenyl diazonium [PhN] ion can be selectively deactivated upon host-guest complexation with cucurbit[7]uril (CB7) in aqueous media, achieving a ∼60-fold increase in the half-life of [PhN].

Rapid Estimation of Binding Constants for Cucurbit[8]uril Ternary Complexes Using Electrochemistry.

Supramolecular complexes are of fundamental interests in biomedicines and adaptive materials, and thus facile methods to determine their binding affinity show usefulness in the design of novel drugs and materials. Herein, we report a novel approach to estimate the binding constants of cucurbit[8]uril-methyl viologen-based ternary complexes (CB8-MV-G2) using electrochemistry, achieving high precision (±0.03) and practical accuracy (±0.

Supramolecular Catalysis of -Xylene Isomerization by Cucurbiturils: Transition State Stabilization, Vibrational Coupling, and Dynamic Binding Equilibrium.

The ability of cucurbit[6]uril () and cucurbit[7]uril () to catalyze the thermally activated 1,2-methyl shift isomerization pathway of -xylene in vacuum is investigated using infrequent metadynamics. is predicted to effectively and selectively catalyze the meta-to-para isomerization through stabilization of the transition state (TS) by van der Waals push (packing coefficient ≈74%), while inhibiting the meta-to-ortho pathway by molding effects of the cavity. Interestingly, despite the snug binding, a very low rate of host-guest vibrational energy transfer is revealed using a novel approach of host-guest partition of the mode-specific anharmonic relaxation rates and molecular dynamics.

Ultrahigh binding affinity of a hydrocarbon guest inside cucurbit[7]uril enhanced by strong host-guest charge matching.

Cucurbit[7]uril (CB[7]) is an artificial macrocyclic molecule that can form exceptionally strong host-guest complexes with binding constants higher than that of the biotin-avidin complex. Despite notable experimental efforts, there do not exist large-scale computational investigations on finding strongly binding guests of CB[7]. Herein, we develop a computational approach based on large-scale molecular modelling to predict strongly binding hydrocarbon motifs.

Preparation of uranium(III) in a molten chloride salt: a redox mechanistic study.

The most advanced methodology for the pyroprocessing of spent nuclear fuel is the electrorefining of uranium metal in LiCl-KCl eutectic, in which uranium is solubilized as U(III). The production of U(III) in LiCl-KCl eutectic by the chlorination of uranium metal using BiCl has been performed for research purposes. In this work, this reaction was studied in-situ by visual observation, electronic absorption spectroscopy and electrochemistry at 450 °C.