Curryyork9299

Ion selective separators with the capability of conducting lithium ion and blocking polysulfides are critical and highly desired for high-performance lithium-sulfur (Li-S) batteries. Herein, we fabricate an ion selective film of covalent organic framework (denoted as TpPa-SO3Li) onto the commercial Celgard separator. The aligned nanochannels and continuous negatively charged sites in the TpPa-SO3Li layer can effectively facilitate the lithium ion conduction and meanwhile significantly suppress the diffusion of polysulfides via the electrostatic interaction. Consequently, the TpPa-SO3Li layer exhibits excellent ion selectivity with an extremely high lithium ion transference number of 0.88. Tie2 kinase inhibitor 1 manufacturer When using this novel functional layer, the Li-S batteries with a high sulfur loading of 5.4 mg cm-2 can acquire a high initial capacity of 822.9 mA h g-1 and high retention rate of 78% after 100 cycles at 0.2 C. This work provides new insights into developing high-performance Li-S batteries via ion selective separator strategy.Ion pair receptors based on meso-octamethylcalix[4]pyrrole (CP) have been extensively investigated over recent years. However, the nature of their ion pair recognition has barely been reported, even for CP itself. Herein, cesium chloride was used as a guest ion pair to investigate the dynamic process of ion pair recognition by CP, and the "capture-bind" mechanism for this process is proposed for the first time. The results reveal that Cs+ can be first captured by Cl- at long distances, and then it is bound to the cavity through almost equal contributions of Cl- and CP. Although the effective charge of Cl- is obviously reduced by charge-transfer, the electrostatic interactions between Cl- and Cs+ are still strong even at long distances in the presence of CP.Herein, we present for the first time a general methodology for obtaining arbitrary-order nuclear coordinate derivatives of electronic energies derived from quantum chemistry methods. By leveraging modern advances in automatic differentiation software, we demonstrate that exact derivatives can be obtained for any method. This innovation completely bypasses the issues associated with the computational stability of applying numerical differentiation methods and dispenses the need to derive challenging formulae for analytic energy derivatives. We describe a freely available and open-source software implementation of our scheme and demonstrate its use in obtaining exact nuclear derivatives of energies from Hartree-Fock theory, second-order Møller-Plesset perturbation theory (MP2), and coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)]. Our sample computations include up to sextic derivatives and span a variety of test systems with up to 100 basis functions, confirming the viability of this scheme for a wide range of applications. Many of the results obtained have hitherto been unobtainable by exact means due to a lack of higher-order derivative formulae. The details of our implementation and possible further developments are discussed.We examined the uptake of Tl(I) by two hexagonal birnessites and related phase transformations in laboratory experiments over 12 sequential additions of 0.01 M Tl(I)/Mn at pH 4.0, 6.0, and 8.0. The Tl-reacted Mn oxides were characterized for their structure, Tl binding, and morphology using X-ray diffraction, X-ray photoelectron and X-ray absorption spectroscopies, and transmission electron microscopy. Very limited Tl oxidation was observed in contrast to previous works, where equal Tl(I)/Mn was added in a single step. Instead, both birnessites transformed into a 2 × 2 tunneled phase with dehydrated Tl(I) in its tunnels at pH 4, but only partially at pH 6, and at pH 8.0 they remained layered. The first four to nine sequential Tl(I)/Mn additions resulted in lower residual dissolved Tl+ concentrations than when the same amounts of Tl(I)/Mn were added in single steps. This study thus shows that the repeated reaction of hexagonal birnessites with smaller Tl(I)/Mn at ambient temperature triggers a complete phase conversion with Tl(I) as the sole reacting cation. The novel pathway found may be more relevant for contaminated environments and may help explain the formation of minerals like thalliomelane [Tl+(Mn7.54+Cu0.52+)O16]; it also points to the possibility that other reducing species trigger similar Mn oxide transformation reactions.Organic transformations exclusively in water as an environmentally friendly and safe medium have drawn significant interest in the recent years. Moreover, transition metal-free synthesis of enantiopure molecules in water will have a great deal of attention as the system will mimic the natural enzymatic reactions. In this work, a new set of proline-derived hydrophobic organocatalysts have been synthesized and utilized for asymmetric Michael reactions in water as the sole reaction medium. Among the various catalysts screened, the catalyst 1 is indeed efficient for stereoselective 1,4-conjugated Michael additions (dr >973, ee up to >99.9%) resulting in high chemical yields (up to 95%) in a very short reaction time (1 h) at room temperature. This methodology provides a robust, green, and convenient protocol and can thus be an important addition to the arsenal of the asymmetric Michael addition reaction. Upon successful implementation, the present strategy also led to the formation of an optically active octahydroindole, the key component found in many natural products.Over the years, researchers in drug discovery have taken advantage of the use of privileged structures to design innovative hit/lead molecules. The α-ketoamide motif is found in many natural products, and it has been widely exploited by medicinal chemists to develop compounds tailored to a vast range of biological targets, thus presenting clinical potential for a plethora of pathological conditions. The purpose of this perspective is to provide insights into the versatility of this chemical moiety as a privileged structure in drug discovery. After a brief analysis of its physical-chemical features and synthetic procedures to obtain it, α-ketoamide-based classes of compounds are reported according to the application of this motif as either a nonreactive or reactive moiety. The goal is to highlight those aspects that may be useful to understanding the perspectives of employing the α-ketoamide moiety in the rational design of compounds able to interact with a specific target.