Latest ArticlesThe utilization of an efficient photocatalyst is crucial for the photocatalytic degradation of antibiotics in water through visible light, which is an imperative requirement for the remediation of water environments. In this study, a novel Cu-CeO2/BiOBr Z-type heterojunction was synthesized by calcination and hydrothermal methods, and the degradation rate of sulfathiazole (STZ) antibiotic solution was studied using simulated illumination (300 W xenon lamp). The results indicated that 3% Cu-CeO2/BiOBr achieved a degradation rate of 92.3% within 90 min when treating 20 mg/L STZ solution, demonstrating its potential for practical water treatment applications. Characterization using various chemical instruments revealed that 3% Cu-CeO2/BiOBr exhibited the lowest electron-hole recombination rate and electron transfer resistance. Furthermore, the utilization of ESR data and quenching experiments has substantiated the involvement of hydroxyl radicals (•OH) and superoxide radicals (•O2−) as the primary active species. Consequently, a plausible degradation mechanism has been inferred. These findings offer a prospective approach for the development of heterojunction materials with appropriate band matching.
Described here is a divergent, biosynthetically inspired synthesis of cochlearol B and ganocin A. Key steps of the synthesis include the chromene unit construction through a biomimetic acid-catalyzed [4 + 2] ring cyclization. A photochemical [2 + 2] cycloaddition was featured to construct the cyclobutane core of cochlearol B. Different skeletal rearrangements of cochlearol B afforded ganocin A, that one of them was Lewis acid mediated epoxide rearrangement and another was DDQ induced cyclobutane formed tetrahydrofuran ring. The described syntheses not only achieved these natural products in an efficient manner, but also provided insight into the biosynthetic relationship between the two different skeletons.
Here, we designed asymmetric (mDS) and symmetrical (dDS) chiral V-shaped molecules by linking one or two dansyl groups to trans-1,2-cyclohexane diamine and investigated the solvent-regulated structural transformation and inversed circularly polarized luminescence (CPL) in the self-assemblies. Upon increasing water volume fraction (fw) in the mixed solvent of water/acetonitrile, asymmetric mDS selfassembled into hollow nanospheres and microtubes, while solid nanospheres and solid microplates were corresponding to symmetric dDS. During this transformation process, the emission of mDS and dDS was changed from yellow-green to blue and cyan color, which was ascribed to twisted intramolecular charge transfer (TICT) and locally excited (LE) fluorescence of V-shaped DS molecules. The conformation of N,N-dimethyl groups with respect to naphthalene ring also led to the transformation of structures. These tubular and platelike structures had stronger and reversed CPL signals in comparison with spheroidal structures. The chiral information of DS assembly could be effective transferred to achiral Nile red via co-assembly strategy, which endowed Nile red exhibiting inversed induced CPL signal regulated by water fraction. This work provides a method for achieving a variety of self-assembled structures with adjustable chiroptical properties.
A highly efficient and concise bromocyclization has been successfully achieved, in which tryptamine/tryptophol derivates can be transformed to valuable HPI/TFI scaffolds with economic and green manners. Moreover, a controllable cascade transformation of bromocyclization and aromatic bromination has also been smoothly achieved to form dibrominated HPIs and TFIs. Production could be successfully scaled up under both the batch process and a continuous flow fashion. The most remarkable peculiarity of our process over all previous methods is that the generated water is the major waste. Notably, successful application of this new protocol has been demonstrated by the pharmaceutical and natural products syntheses.
Improving the highly selective and sensitive binding of chemosensor to target guest is always very challenging. In order to solve this issue, herein, the enrichment effect was introduced into the design of chemosensor molecule. A novel bi-fused-macrocyclic host molecule BPN1 was synthesized by bridging a pillar[5]arene and a naphthalene diimide (NDI) group through hydrogen-bond-rich chain. In the BPN1, the naphthalimide side ring is outside the cavity of the pillar[5]arene. In addition, Cr(Ⅵ) greatly threat human health and the environment due to its severe toxicity, and it is very important to develop effective chemosensor for sensitive and selective detection of Cr2O72− or its ion pairs. In this paper, the novel bi-fused-macrocyclic host molecule BPN1 can recognize Cr2O72− with high selectivity and sensitivity. The mechanism of BPN1 recognition of Cr2O72− was studied through experiments and density functional theory (DFT), the results show that BPN1 could supply enrichment effect to bind Cr2O72− through multiple weak interactions such as hydrogen bonds and anion-π, and achieve highly sensitive and selective detection of Cr2O72−. It is a significant and feasible strategy for improve high selectivity and sensitivity of host to specific objects by using the enrichment effect of fused bi-macrocyclic.
Transition-metal-catalyzed cross-electrophile coupling has emerged as a reliable method for constructing carbon–carbon bonds. Herein, we report a general method, cobalt-catalyzed reductive alkynylation, to construct C(sp)-C(sp3) and C(sp)-C(sp2) bonds. This presented reaction has a broad substrate scope, enabling the efficient cross-electrophile coupling between alkynyl bromides with alkyl halides and aryl or alkenyl (pseudo)halides. This presented reaction is conducted under mild conditions, tolerating many functional groups, thus suitable for the modification and synthesis of biologically active molecules.
Anode free lithium metal batteries (AF-LMBs) have conspicuous advantages both in energy density and the compatibility of battery manufacturing process. However, the limited cycle life of AF-LMBs is a crucial factor hindering its practical application. Fluorinated or nitride artificial inorganic solid electrolyte interphase (SEI) has been found as an effective method to prolong the lifespan of AF-LMBs. Herein, by investigating the impact of nano-sized inorganic gradient layers (LiF or Li3N) on initial Li deposition behavior, we notice that the Li+ diffusion barrier and the deposition morphology are highly depended on the thickness of inorganic layers. Thicker protective layers cause larger overpotential as well as more aggregated Li+ distribution. This study reveals that the ideal SEI should be synthesized thin and uniformly enough and uncontrollable artificial SEI can cause damage to the lifespan of AF-LMBs.
A nonsymmetrical PNN pincer ligand [6-(Bu2PNH)C5H4N-2-(3-Mes)C3H2N2] and its corresponding cobalt-N2 complex were synthesized and characterized. By the stoichiometric reaction of the PNN ligand lithium salt with CoCl2, the complex 3, (PNN)CoCl, was obtained. Then, reduction of 3 with NaBHEt3 under a dinitrogen atmosphere yielded complex 5, (PNN)Co(Ⅰ)(η1-N2). Single-crystal X-ray analysis, IR spectrum, and DFT calculations revealed that the dinitrogen in 5 was only weakly reduced by the cobalt center. The reactions of 5 with carbon monoxide and 2, 6-dimethylphenyl isocyanide gave carbonyl and isocyanide complexes 6 and 7 with the release of N2, respectively. Furthermore, these cobalt complexes, especially complex 5, demonstrated the capacity to convert dinitrogen to N(TMS)3 with moderate efficiency.
A copper(Ⅰ)-catalyzed diastereodivergent addition of phosphinothioates (HP(S)ROR') to α, β-unsaturated thioamides is disclosed, which constructs vicinal P-chiral and C-chiral centers in generally high diastereo- and enantioselectivities. In this reaction, the kinetic resolution of HP(S)ROR' occurs, which affords (R)-HP(S)PhOMe in high enantioselectivity in the addition with (R, R)-Ph-BPE as the ligand. It is found through control experiment that dual "soft-soft" interaction, indicated by both 1H and 31P NMR experiments, is indispensable in the present reaction. The first "soft-soft" interaction between copper(Ⅰ) catalyst and HP(S)ROR' enables facile deprotonation to generate nucleophilic [Cu]-SPROR' species. The second one between the [Cu]-SPROR' species and α, β-unsaturated thioamides facilitated the nucleophilic addition. Finally, both Michael adducts and (R)-HP(S)PhOMe are easily converted to synthetically useful compounds.
The conjugate addition of in-situ generated (aza-)quinone methides (QMs) and indole imine methides (IIMs) emerged as a powerful protocol to access densely functionalized benzenes and indoles. Hydroxybenzyl alcohols, aminobenzhydryl alcohols, and varied indolylmethanols served as most effective precursors for the in-situ generation of such reactive species under acid conditions. The relevant propargylic alcohol has proven to be an elegant precursor to generate the propargylic-QMs and -IIMs via the acid promoted dehydration process, thus enabling diverse challenging remote activation to proceed conjugate 1,6- and 1,8-additions. Moreover, the heteroarene has proven to be workable to transfer the LUMO of the p-QMs and 2-IIMs, thus inducing the remote nucleophilic dearomative additions. The conjugate additions of (aza-)p-QMs and varied IIMs has made significant contribution in the field of remote activation chemistry in past decade. This review summarizes the latest advances of the remote conjugate additions of the in-situ generated QMs and IIMs.
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