Encapsulation of charge-diffuse peralkylated onium cations in the cavity of cucurbit[7]uril

Cucurbit[7]uril binds, with considerable size selectivity, NR(4)(+), PR(4)(+), and SR(3)(+) cations (R=Me, Et, (n)Pr, (n)Bu), with the smaller guests inside its cavity, rather than at the carbonyl-lined portals.     

Cucurbit[7]uril host-guest complexes with small polar organic guests in aqueous solution

The host-guest stability constants for the inclusion of a series of small neutral polar organic guests in cucurbit[7]uril (CB[7]) have been determined in aqueous solution by (1)H NMR titrations. The dependence of the stability constant on the nature of the guests indicates that hydrophobic and dipole-quadrupole interactions are responsible for the binding. The complexation-induced chemical shift changes in the guest proton resonances, coupled with energy-minimization calculations, suggest that the guests are located such that their dipole moment is aligned perpendicular with the quadrupole moment of the CB[7] host. The stability constants for acetone and acetophenone decrease in the presence of Na(+) or K(+) cations as a result of cation capping of the CB[7] portals.     

Matrix measure on time scales and almost periodic analysis of the impulsive Lasota–Wazewska model with patch structure and forced perturbations

In this paper, a new impulsive Lasota–Wazewska model with patch structure and forced perturbed terms is proposed and analyzed on almost periodic time scales. For this, we introduce the concept of matrix measure on time scales and obtain some of its properties. Then, sufficient conditions are established which ensure the existence and exponential stability of positive almost periodic solutions of the proposed biological model. Our results are new even when the time scale is almost periodic, in particular, for periodic time scales on or . An example is given to illustrate the theory. Finally, we present some phenomena which are triggered by almost periodic time scales. Copyright © 2016 John Wiley & Sons, Ltd.     

Weak solutions for fractional differential equations in nonreflexive Banach spaces via Riemann‐Pettis integrals

The aim of this paper is to develop fractional calculus for vector‐valued functions using the weak Riemann integral. Also, we establish the existence of weak solutions for a class of fractional differential equations with fractional weak derivatives.     

Cucurbit[8]uril/cucurbit[7]uril controlled off/on fluorescence of the acridizinium and 9-aminoacridizinium cations in aqueous solution

The blue fluorescence of acridizinium bromide (ADZ+) and the green fluorescence of 9-aminoacridizinium bromide (AADZ+) in aqueous solutions can be almost entirely switched off upon the double inclusion of these guests in the cavity of cucurbit[8]uril (CB[8]) owing to the formation of a nonfluorescent, noncovalent dimer complex, and then fluorescence can be effectively restored by adding cucurbit[7]uril (CB[7]) to the complex because it competitively extracts the fluorophores out of the CB[8] cavity.     

On a New Class of Abstract Neutral Integro-Differential Equations and Applications

In this paper we introduce a new class of abstract integro-differential equations with delay and we study the existence of strict solutions. An application involving the heat equation with memory is presented.     

Existence to singular boundary value problems with sign changing nonlinearities using an approximation method approach

This paper studies the existence of solutions to the singular boundary value problem

Development and application of a direct vinyl lithiation of cis-stilbene and a directed vinyl lithiation of an unsymmetrical cis-stilbene

[reaction: see text] The vinyl deprotonation of cis-stilbene can be readily achieved using s-BuLi in THF at -25 degrees C. The generated 1-lithio-1,2-diphenylethene undergoes an in situ Z-to-E isomerization, and subsequent reaction with electrophiles results in an efficient stereoselective synthesis of trisubstituted alkenes. A directed vinyl lithiation of the unsymmetrical cis-stilbene 2-styryl-phenyl-carbamic acid tert-butyl ester can be achieved regioselectively, thereby expanding this methodology for further synthetic applications in indole chemistry.