Activiteit

Ethyl and phenyl thioglycosides are the two most common types of thioglycoside donors in carbohydrate chemistry. However, the chemoselective activation of ethyl vs. phenyl thioglycosides is very rare in the literature. In this work, ethyl thioglycosides could be readily activated with an N-trifluoromethylthiosaccharin/TMSOTf system in the presence of phenyl thioglycosides carrying the same or even more armed protecting group pattern. Both armed and disarmed thioglycosides exhibited high chemoselectivity towards the promoter system. Chemoselective glycosylation was subsequently applied to one-pot synthesis, thus providing an efficient means to oligosaccharides.Functionalization of metal-organic framework (MOF) ligands can tune the adsorption properties of MOFs. The adsorptions of NO, NO2, NH3, C5H5N, C4H5N, and C4H4O on pristine and five X-functionalized HKUST-1, i.e. read more Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylate) (X = CH3, CH3O, NH2, NO2, and Br) are evaluated by van der Waals corrected density functional theory calculations. Despite the fact that the open metal center is the energetically preferred adsorption site for most of them, the functional group site can yield a comparable adsorption ability with the open metal center. This is particularly true for pyrrole C4H5N adsorption on CH3O-functionalized HKUST-1 where the functional group site shows stronger adsorption stability than the open metal center site, probably due to the formed hydrogen bond between pyrrole and the CH3O functional group. While the CH3- or CH3O-functionalized organic linker in these MOFs strengthens the adsorption of all the considered species, that of NO2-, Br-, or NH2-functional groups reduces, which is associated with their topologies. Among them, only CH3- or CH3O-functionalized HKUST-1 presents the fmj (orthorhombic crystal system) topology while all the others are isostructural to the pristine HKUST-1 with the tbo (twisted boracite-type, cubic) topological structure. Among six adsorbates, two basic adsorbates, C5H5N and NH3, always yield the strongest bonding strength upon adsorption on the pristine and five functionalized HKUST-1. Electronic properties including the Bader charges, electron density differences, and electron localization function were investigated to comprehend their adsorption behaviors. This work provides guidance for the proper functionalization of HKUST-1 with improved adsorption properties for specific adsorbates.Three Zr(iv)-substituted polyoxometalate nanoclusters, H16(H2dap)4[Zr2(OH)2(α-SiW10O38)2Zr2(OH)2(β-SiW10O38)2]·8H2O (1, dap = 1,3-diaminopropane), H17Na9[(Zr2(OH)2)2(Zr2BO(OH)4)2(β-SiW10O38)4]·50H2O (2) and H20Na8[(Zr2BO(OH)4)2(Zr2B2O2(OH)5)2(β-SiW10O38)4]·40H2O (3), were made by a hydrothermal reaction of trivacant [A-α-SiW9O34]10-, Zr4+ ions, and H3BO3 under different alkaline conditions. Single-crystal X-ray structure analysis revealed that they are ring-shaped polyoxotungstate aggregates built by Zr2(OH)2 (Zr2) clusters and two types of dilacunary α-/β-SiW10O38 (α-/β-SiW10) fragments for 1, Zr2, β-SiW10, and Zr2BO(OH)4 (Zr2B) clusters for 2, and β-SiW10, Zr2B, and Zr2B2O2(OH)5 (Zr2B2) clusters for 3, respectively, showing that the Zr-B-O clusters, Zr2B and Zr2B2, have been introduced to the lacunary sites of polyoxometalates for the first time. The electrochemistry and electrocatalytic properties of 2 were studied, and it exhibited effective catalytic activities for the reduction of H2O2, NO2-, and BrO3-. Moreover, the catalysis of 2 for the oxidation reactions of various thioethers was investigated, and it was found that 2 possessed high conversion and remarkable selectivity.From the viewpoint of inorganic crystal engineering (ICE), the coordination sphere of the metal centre can be affected by two main parts of inorganic and organic units in complexes. Database study can play a significant role in the explanation of the relationship between various parameters related to these parts. For the first time, we have investigated this relationship through the concomitant studies of the inorganic crystal structure database (ICSD) and the cambridge structural database (CSD) for mercury(ii) halide compounds. The results of CSD analysis are divided into two categories of metal halide complexes (MHC or mercury halide compounds with ligands) and metal halide only (MHO or mercury halide compounds without ligands). MHC (970, 460, and 521 metal centres as HgCl2, HgBr2, and HgI2, respectively) and MHO (419, 141, and 201 metal centres as HgCl2, HgBr2, and HgI2, respectively) were structurally investigated. The coordination number, polymerization mode, coordination geometry of the metal centre, tyanic unit can also change the coordination sphere of complexes with one major effect or the cooperativity of minor effects.Referred to as the “guardian of the genome”, p53 is the most frequently mutated protein in cancer and almost all cancers exhibit malfunction along the p53 pathway. As an overexpressed and tumour-specific target, the past two decades have seen considerable dedication to the development of small molecules that aim to restore wild-type function in mutant p53. In this review we collect and communicate the chemical principles involved in small molecule drug design for misfolded proteins in anticancer therapy. While this approach has met with significant challenges including off-target mechanisms that induce cytotoxicity independent of p53 status, major technological advancements in gene sequencing capability and a shift towards personalized medicine holds significant promise for p53 reactivating compounds and could have widespread benefits for the field of cancer therapy.Tremendous effort has been devoted to develop durable electrode materials for sodium ion batteries. This work focuses on enhancing the reversibility of a cathode material Na0.5Ni0.25Mn0.75O2 by adopting the titanium cation doping strategy. The obtained P2-Na0.5Ni0.25Mn0.60Ti0.15O2 material shows smooth charge-discharge curves upon suppressing the Na+/vacancy ordering effect via the partial substitution of Mn4+ for Ti4+, and enhanced cycling performance. It exhibits a reversible capacity of 138 mA h g-1 at 0.5C, as well as a high rate capacity of 81 mA h g-1 at 5C between a cut-off voltage of 2 and 4 V, while long-term cycling stability is demonstrated with a capacity retention of 84% over 200 cycles. An enhanced cycling stability is also observed when the voltage is between 2 and 4.2 V. The feasibility of constructing a symmetrical Na-ion full cell with Na0.5Ni0.25Mn0.60Ti0.15O2 as cathode and anode electrodes is also demonstrated. The titanium cation doping results in reduced charge transfer impedance and an enhanced sodium cation diffusion coefficient, thus suggesting an efficient strategy to obtain a durable cathode material for sodium ion batteries.