Getting a fix: The copper‐catalyzed hydrocarboxylation of alkynes using carbon dioxide in the presence of a hydrosilane, which serves as a reducing agent, has been developed (see scheme). Copper ...fluorides bearing N‐heterocyclic carbene ligands such as IMes and Cl2IPr show high catalytic activities.
Precision synthesis of advanced polymeric materials requires efficient, robust, and facile chemical reactions. Paradoxically, the synthesis of increasingly intricate macromolecular structures ...generally benefits from exploitation of the simplest reactions available. This idea, combined with requirements of high efficiency, orthogonality, and simplified purification procedures, has led to the rapid adoption of “click chemistry” strategies in the field of macromolecular engineering. This Perspective provides context as to why these newly developed or recently reinvigorated reactions have been so readily embraced for the preparation of polymers with advanced macromolecular topologies, increased functionality, and unique properties. By highlighting important examples that rely on click chemistry techniques, including copper(I)-catalyzed and strain-promoted azide−alkyne cycloadditions, Diels−Alder cycloadditions, and thiol−ene reactions, among others, we hope to provide a succinct overview of the current state of the art and future impact these strategies will have on polymer chemistry and macromolecular engineering.
More hip than nano: Bielawski and co‐workers recently demonstrated the remarkable ability of graphene oxide to catalyze the oxidation of a variety of alcohols to the corresponding ketones/aldehydes, ...alkenes to the corresponding diones, and alkynes to the corresponding hydrates—a process they termed “carbocatalysis”. These efficient metal‐free reactions mark a promising convergence of heterogeneous catalysis with graphene science.
Graphdiine (engl. graphdiynes=GDYs) sind zweidimensionale graphenähnliche Kohlenstoffsysteme und gelten aufgrund ihrer einzigartigen physikalisch‐chemischen Eigenschaften als potenzielles ...Membranmaterial. Die Maßstabvergrößerung der Präparation von GDY‐Membranen ist jedoch eine technologische Herausforderung. Wir berichten hier über eine einfache und effiziente alkinierte oberflächenvermittelte Strategie zur Herstellung von wasserstoffsubstituierten Graphdiin1c (HsGDY)‐Membranen auf kommerziellen Aluminiumoxidrohren, die zuvor Alkin‐modifiziert wurden. Die Oberflächenalkinierung der Keramik erlaubt eine oberflächenbegrenzte Kupplungsreaktion in Gegenwart eines Kupferkatalysators und ermöglicht so das epitaktische Wachstum von HsGDY im Nanomaßstab. Eine kontinuierliche und ultradünne HsGDY‐Membran (∼100 nm) kann innerhalb von 15 min hergestellt werden. Die resultierenden Membranen weisen eine sehr hohe Molekularsiebung zusammen mit hervorragender Wasserpermeanz (ca. 1100 L m−2 h−1 MPa−1) auf und zeigen aufgrund der superhydrophilen Oberfläche und hydrophoben Porenwände ein stabiles Trennverhalten in der Cross‐Flow‐Nanofiltration.
Hydrogen‐substituted graphdiyne (HsGDY)‐based membranes are prepared on alkynylated commercial ceramic tubes, overcoming the limitation that such layers could be synthesized so far only on a limited number of metal surfaces. The prepared HsGDY layers are strongly attached to the ceramic surface and exhibit excellent molecular permselectivity and ultra‐high water permeance due to the unique surface properties and peculiar conjugated structure.
Entering the iron age: The first general method for iron‐catalyzed monocarbonylation of alkynes has been developed. A range of structurally diverse cinnamides and acrylamides have been obtained ...smoothly starting from commercially available amines and alkynes in the presence of Fe3(CO)12 and ligand L (see scheme). The method is highly chemo‐ and regioselective and requires no expensive catalyst.
One source of learning in universities is a digital library. In the era of industry 4.0, most universities have implemented digital libraries in supporting the learning process. However, the reality ...shows that digital library management is still ineffective. Therefore, the implementation of digital libraries needs to be evaluated for determining the digital library effectiveness used as learning resources in supporting the learning process in universities. Many evaluation tools are used to evaluate the effectiveness of digital libraries but have not provided accurate recommendation results to support decision-making. This research presents an innovation in the form of an evaluation tool that can be used to evaluate the digital library effectiveness in universities. That evaluation tool is called the Alkin-WP-based digital library evaluation software. This software is a desktop platform that contains aspects of measuring the digital library effectiveness by referring to the components of the Alkin evaluation model and the WP (Weighted Product) method. This research aimed to show the effectiveness level of the utilization of Alkin-WP-based digital library evaluation software. This research method was R & D (Research & Development) which refers to the ten development stages of the Borg and Gall model. In this research, development was focused only on a few stages, included: usage trials, final product revision, dissemination, and implementation. The subjects involved in assessing the implementation/utilization of the Alkin-WP-based digital library evaluation software were 35 people, in the usage trials were six people, in product revision were three people, and at the stage of dissemination were 15 people. The tools used to collect data were questionnaires and interview guidelines. The data analysis technique used was descriptive quantitative. The effectiveness level of utilizing the Alkin-WP-based digital library evaluation software was 88.34%. It showed that the evaluation software had effective. The impact of this research results on the scientific field of educational evaluation is being able to show the existence of a new evaluation tool based on educational evaluation and artificial intelligence. That evaluation tool can easier for library heads to make policies for revamping digital library services based on accurate recommendations. Doi: 10.28991/esj-2021-01308 Full Text: PDF
A new type of molybdenum alkylidyne catalysts for alkyne metathesis is described, which is distinguished by an unconventional podand topology. These structurally well‐defined complexes are easy to ...make on scale and proved to be tolerant toward numerous functional groups; even certain protic substituents were found to be compatible. The new catalysts were characterized by X‐ray crystallography and by spectroscopic means, including 95Mo NMR.
Ligandendach: Molybdän‐Alkylidin‐Komplexe mit Triarylsilanolat‐Liganden sind privilegierte Katalysatoren für die Alkin‐Metathese, die Verknüpfung der Silylgruppen mit einem Ligandengerüst scheint die Sache aber noch besser zu machen. Kristallographische Daten und eine seltene Fallstudie basierend auf 95Mo‐NMR‐Spektroskopie liefern Erkenntnisse darüber, warum das so ist.
Nukleinsäuren in Form von siRNA, Antisense‐Oligonukleotiden oder mRNA werden derzeit als neue vielversprechende Modalitäten in der pharmazeutischen Industrie erforscht. Insbesondere der Erfolg von ...mRNA‐Impfstoffen gegen SARS‐CoV‐2 sowie die erfolgreiche Entwicklung der ersten zuckermodifizierten siRNA‐Therapeutika haben das Feld beflügelt. Die Entwicklung von Nukleinsäuretherapeutika erfordert eine effiziente Chemie, um Oligonukleotide mit chemischen Strukturen zu verknüpfen, die die Stabilität verbessern, die Aufnahme in die Zellen fördern oder eine spezifische Adressierung ermöglichen. Für die derzeit verwendeten siRNA‐Therapeutika hat sich die Modifizierung des 3′‐Endes der Oligonukleotide mit Triple‐N‐Acetylgalactosamin (GalNAc)3 als wichtig erwiesen. Diese Modifikation wird derzeit durch eine umständliche, mehrstufige Synthese und anschließende Beladung auf das Trägermaterial erreicht. Hier berichten wir über die Entwicklung eines bifunktionellen, klickreaktiven Linkers, der die Modifizierung von Oligonukleotiden in einer Tandem‐Klickreaktion mit multiplen Zuckern, unabhängig von der Position innerhalb des Oligonukleotids, mit bemerkenswerter Effizienz und in einer Ein‐Topf Reaktion ermöglicht.
Es wurde ein neuer bifunktionaler, dendrimerer Linker entwickelt, der die Modifizierung von Oligonukleotiden in einer Tandem‐Klickreaktion mit mehreren Zuckern in nur einem Schritt ermöglicht. Die Methode nutzt die unterschiedlichen Klick‐Reaktivitäten der Linker‐Azide in einer Cu‐katalysierten Reaktion mit Alkinen aus. Die neue Methode ist schnell, hochselektiv und ermöglicht die Modifizierung des Oligonukleotids mit mehreren Zuckern an jeder beliebigen Position.
We report the functionalization of cross-linked poly(divinylbenzene) (pDVB) microspheres using both thiol−ene chemistry and azide−alkyne click reactions. The RAFT technique was carried out to ...synthesize SH-functionalized poly(N-isopropylacrylamide) (pNIPAAm) and utilized to generate pNIPAAm surface-modified microspheres via thiol−ene modification. The accessible double bonds on the surface of the microspheres allow the direct coupling with thiol-end functionalized pNIPAAm. In a second approach, pDVB microspheres were grafted with poly(2-hydroxyethyl methacrylate) (pHEMA). For this purpose, the residual double bonds on the microspheres surface were used to attach azide groups via the thiol−ene approach of 1-azido-undecane-11-thiol. In a second step, alkyne endfunctionalized pHEMA was used to graft pHEMA to the azide-modified surface via click-chemistry (Huisgen 1,3-dipolar cycloaddition). The surface-sensitive characterization methods X-ray photoelectron spectroscopy, scanning-electron microscopy and FT-IR transmission spectroscopy were employed to characterize the successful surface modification of the microspheres. In addition, fluorescence microscopy confirms the presence of grafted pHEMA chains after labeling with Rhodamine B.
Transition metal complexes catalyze many important reactions that are employed in medicine, materials science, and energy production. Although high-throughput methods for the discovery of catalysts ...that would mirror related approaches for the discovery of medicinally active compounds have been the focus of much attention, these methods have not been sufficiently general or accessible to typical synthetic laboratories to be adopted widely. We report a method to evaluate a broad range of catalysts for potential coupling reactions with the use of simple laboratory equipment. Specifically, we screen an array of catalysts and ligands with a diverse mixture of substrates and then use mass spectrometry to identify reaction products that, by design, exceed the mass of any single substrate. With this method, we discovered a copper-catalyzed alkyne hydroamination and two nickel-catalyzed hydroarylation reactions, each of which displays excellent functional-group tolerance.
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