jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Bryan J. Foley
Source: OakTrust (Texas A&M University Libraries) (article, 2020-05-19)
Field: Chemistry — Inorganic Chemistry

The Kinetics of the Dehydrogenative Borylation of Terminal Alkynes and Exploration of the Reactivity of PXP Ligated Cobalt Complexes Catalytic synthesis of borylated organic molecules has been of great interest given the synthetic utility of borylated material in cross-coupling reactions. However, a glaring absence from the synthetic chemist’s repertoire was the catalytic synthesis of borylated alkynes. In 2013, the Ozerov group disclosed pincer iridium complexes capable of performing the dehydrogenative borylation of terminal alkynes (DHBTA). In the following years, second generation catalysts were disclosed using the 2,2’-bis(dialkylphosphino)diphenylamide (PNP) ligand.\n\nHere we continue the development of PNP ligated iridium DHBTA catalysts and disclose a full mechanistic investigation coupling experimental results with computational investigation. Also disclosed is the first example of a readily available, air-stable iridium DHBTA precatalyst. We have discovered that the DHBTA reaction is moderately tolerant to air and moisture with sufficient pinacolborane present. The ease of handling this new precatalyst will hopefully inspire widespread use of catalytic methods for the construction of alkynylboronates.\n\nInspired by our success with (POCOP)Rh(Ar)(SAr’) and (PNP)Rh(Ar)(SAr’) in C–S bond formation reactions, (POCOP)Co(Ar)(SAr’) and (PNP)Co(Ar)(SAr’) were synthesized and their efficacy in C–S bond formation was investigated. The (POCOP)Co and (PNP)Co platforms were determined to be incapable of supporting catalysis. The former was prone to reductive elimination involving the pincer aryl and the latter was plagued by a swift comproportionation reaction after concerted two electron C–S reductive elimination. The mechanism of thiolate scrambling and C–S coupling in the (PNP)Co system was investigated in detail. A series of aryl halides were added to the (PNP)Co system to capture cobalt after reductive elimination hopefully eliciting oxidative addition to the unsaturated (PNP)Co fragment; however, halogen atom abstraction predominated. The halogen atom abstraction and scrambling of ligands between cobalt centers was investigated.\n\nEsterified phenols are attractive substrates for Suzuki-style coupling reactions given the ubiquity of phenols and the stability of the corresponding ester. To this end, the (PNP)Co system was applied to the C–O cleavage of esters. Although the active CoI/III comproportionation reaction prevents catalysis, this is the first documented example of cobalt mediated aryl ester C–O bond activation.\n\nLastly, the synthesis, characterization, and structural characterization of various cobalt silylene complexes are disclosed. Cobalt ; Kinetics ; Chemistry ; Terminal (telecommunication) ; Borylation ; Reactivity (psychology) ; Stereochemistry ; Medicinal chemistry ; Computer science ; Organic chemistry ; Medicine ; Computer network ; Physics Asymmetric Hydrogenation and Catalysis ; Carbon dioxide utilization in catalysis ; Organometallic Complex Synthesis and Catalysis
Authors: Saul T. E. Jones | Andrew J. Pearson | Jeremy D. Dang | Neil C. Greenham | Timothy P. Bender | Dan Credgington
Source: ChemRxiv (preprint, 2020-12-14)
Field: Materials Science — Materials Chemistry

Exploring the Effects of Bay Position Chlorination on the Emissive Properties of Chloro-(Chloro)n-Boron Subnaphthalocyanines for Light Emission. &lt;p&gt;&lt;b&gt;Abstract:&lt;/b&gt; It has been previously found that through an established synthesis of the macrocycle boron subnaphthalocyanine (BsubNc) that random bay-position chlorination occurs and results in a mixed alloyed composition that cannot be separated; called chloro-(chloro&lt;sub&gt;n&lt;/sub&gt;)-boron subnaphthalocyanines (Cl-Cl&lt;sub&gt;n&lt;/sub&gt;BsubNcs). Through modifications of the synthetic method, amounts of the average bay-position chlorination can be varied. Cl-Cl&lt;sub&gt;n&lt;/sub&gt;BsubNcs are fluorescent and therefore here we explore the effect of the amount of bay-position chlorination on the photoluminescent and electroluminescent properties of Cl-Cl&lt;sub&gt;n&lt;/sub&gt;BsubNcs. Distinct from previous reports detailing the positive impact of higher average bay-position chlorination, we find that the photophysical processes important to OLEDs improve with lower average bay-position chlorination. A higher degree of bay-position chlorine shows higher nonradiative recombination rates, lower photoluminescence quantum efficiencies and a basic OLEDs exhibits a greater host emission fraction, implying less effective energy transfer. These results advance the consideration of subnaphthalocyanines for light-emitting and optoelectronic applications.&lt;/p&gt; Bay ; Boron ; Chlorine ; Photoluminescence ; Chlorine atom ; Chemistry ; Electroluminescence ; Fluorescence ; Photochemistry ; Materials science ; Medicinal chemistry ; Physics ; Optoelectronics ; Organic chemistry ; Optics Porphyrin and Phthalocyanine Chemistry
Authors: Siwen Bi | W. You | P.A. Rupar | N. Bauer | H. Cao | D. Li
Source: UNC Libraries (article, 2020-08-20)
Field: Chemistry — Inorganic Chemistry

Post-polymerization modification of phosphorus containing conjugated copolymers A new phosphafluorene (PF) based monomer, featuring a phosphine oxide substituted with a dodecyl chain, was synthesized. PF was copolymerized with benzodithiophene (BDTT) to form the copolymer PPF-BDTT which has a donor (BDTT)–acceptor (PF) structure. For the first time, direct post-polymerization modifications were performed on the phosphorus center of phosphafluorene-containing conjugated polymers. With Lawesson's Reagent, PPF-BDTT was transformed from a phosphine oxide to a phosphine sulfide. Reduction of the phosphine oxide of PPF-BDTT with HSiCl3, followed by reaction with AuCl∙SMe2, produced PPF-BDTT-Au, which contains AuCl coordinated to the phosphafluorene moiety. PPF-BDTT, PPF-BDTT-S, and PPF-BDTT-Au were characterized optically and electrochemically and the results compared to related BDTT containing copolymers. PPF-BDTT and its derivatives were found to have high LUMO and HOMO levels and larger bandgaps compared to common donor-acceptor copolymers. Organic solar cells were fabricated from PPF-BDTT, PPF-BDTT-S, and PPF-BDTT-Au, although the performances of these devices were poor with power conversion efficiencies ranging from 0.13% to 0.60%. Conjugated system ; Copolymer ; Polymerization ; Phosphorus ; Chemistry ; Polymer chemistry ; Combinatorial chemistry ; Organic chemistry ; Polymer Synthesis and characterization of novel inorganic/organometallic compounds
Authors: Benoît Denis Louis Campéon
Source: Institutional Repositories DataBase (IRDB) (article, 2020-09-25)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Electrochemical synthesis and functionalization of graphene materials for energy storage devices CHAPTER 4 Iron nanoparticle templates for constructing 3D graphene frame-work with Surface modification ; Graphene ; Electrochemical energy storage ; Nanotechnology ; Materials science ; Energy storage ; Electrochemistry ; Chemistry ; Chemical engineering ; Supercapacitor ; Electrode ; Engineering ; Physics ; Power (physics) Supercapacitor Materials and Fabrication ; Advancements in Battery Materials
Authors: Yongmei Xu | Juzheng Sheng | Xuefei Huang | Steven B. Dulaney | Jian Liu
Source: UNC Libraries (article, 2020-11-09)
Field: Chemistry — Organic Chemistry

Uncovering Biphasic Catalytic Mode of C 5 -epimerase in Heparan Sulfate Biosynthesis Heparan sulfate (HS), a highly sulfated polysaccharide, is biosynthesized through a pathway involving several enzymes. C5-epimerase (C5-epi) is a key enzyme in this pathway. C5-epi is known for being a two-way catalytic enzyme, displaying a “reversible” catalytic mode by converting a glucuronic acid to an iduronic acid residue, and vice versa. Here, we discovered that C5-epi can also serve as a one-way catalyst to convert a glucuronic acid to an iduronic acid residue, displaying an “irreversible” catalytic mode. Our data indicated that the reversible or irreversible catalytic mode strictly depends on the saccharide substrate structures. The biphasic mode of C5-epi offers a novel mechanism to regulate the biosynthesis of HS with the desired biological functions. Heparan sulfate ; Biosynthesis ; Sulfate ; Catalysis ; Chemistry ; Biochemistry ; Cell biology ; Stereochemistry ; Biology ; Enzyme ; Organic chemistry ; Glycosaminoglycan Carbohydrate Chemistry and Synthesis ; Proteoglycans and glycosaminoglycans research
Authors: Taeho Kang | Tuğçe G. Erbay | Kane L. Xu | Gary M. Gallego | Alexander Burtea | Sajiv K. Nair | Ryan L. Patman | Ru Zhou | Scott C. Sutton | Indrawan McAlpine | Peng Liu | Keary M. Engle
Source: ChemRxiv (preprint, 2020-08-12)
Field: Chemistry — Organic Chemistry

Multifaceted Substrate–Ligand Interactions Promote the Copper-Catalyzed Hydroboration of Benzylidenecyclobutanes and Related Compounds A unified synthetic strategy to access tertiary four-membered carbo/heterocyclic boronic esters is reported. Use of a Cu(I) catalyst in combination with a modified dppbz ligand enables regioselective hydroboration of various substituted benzylidenecyclobutanes and carbo/heterocyclic analogs. The reaction conditions are mild, and the method tolerates a wide range of medicinally relevant heteroarenes. The protocol can be conveniently conducted on gram-scale, and the tertiary boronic ester products undergo facile diversification into valuable targets. Reaction kinetics and computational studies indicate that the migratory insertion step is turnover-limiting and accelerated by electron-withdrawing groups on the dppbz ligand. Energy decomposition analysis (EDA) calculations reveal that electron-deficient P-aryl groups on the dppbz ligand enhance the T-shaped π/π interactions with the substrate and stabilize the migratory insertion transition state. Hydroboration ; Chemistry ; Ligand (biochemistry) ; Catalysis ; Combinatorial chemistry ; Regioselectivity ; Aryl ; Substrate (aquarium) ; Organic chemistry ; Receptor ; Biochemistry Organoboron and organosilicon chemistry ; Asymmetric Hydrogenation and Catalysis ; Chemical Synthesis and Analysis
Authors: Arto Hiltunen
Source: Tampere University Institutional Repository (Tampere University) (article, 2020-01-01)
Field: Materials Science — Surfaces, Coatings and Films

Photovoltaic Applications of Porous Atomic Layer Deposited Metal Oxides from Cellulose Templates Fossiilisten polttoaineiden liiallisesta käytöstä aiheutuvan ilmaston lämpenemisen ennustetaan vaikuttavan negatiivisesti elämämme laatuun. Lämpenemisen pysäyttämiseksi tulisi etsiä vaihtoehtoisia energiantuottotapoja öljyn, hiilen ja kaasun polttamiselle. Useissa tulevaisuudennäkymissä vety nostetaan esille kaikkein lupaavimpana vaihtoehtona fossiilisten polttoaineiden korvaajaksi. Vetyä voidaan&#13;\n erottaa vedestä vetykaasuna, joka voidaan polttaa lämmöksi tai muuntaa sähköksi sähkökemiallisessa kennossa. Molemmissa prosesseissa vety reagoi hapen kanssa muodostaen vettä ainoana päästönään. Näin ollen vety voisi taata hiilidioksidivapaan lämmön- ja sähkönlähteen, mikäli vedyn tuottamiseen käytetty energia olisi hiilidioksidivapaata. Tämä väitöskirja käsittelee materiaaleja, jotka pystyvät tuottamaan vetykaasua vedestä käyttäen energianlähteenä auringonvaloa.&#13;\n &#13;\nTässä työssä valmistimme huokoisia metallioksidinanorakenteita selluloosamuotteja apuna käyttäen. Muottien avulla valmistettujen materiaalien tehokkuus testattiin valokemiallisessa vedyntuotannossa sekä väriaineaurinkokennojen elektrodeina. Rakenteiden valmistaminen alkaa huokoisen selluloosamuotin levittämisellä, joka päällystetään seuraavassa vaiheessa titaanidioksidilla käyttäen atomikerroskasvatustekniikkaa (ALD). Titaanidioksidikerroksen paksuutta kyettiin optimoimaan ALDtekniikan nanometriluokan tarkkuuden avulla, jolloin vedyntuotannon tehokkuutta pystyttiin parantamaan. Tutkiessamme useita eri pinnoitepaksuuksia onnistuimme lisäksi kuvaamaan ALD:llä kasvatettujen titaanidioksidikalvojen kasvun etenemistä selluloosamuottien päällä. Väitöskirjatyön viimeisessä vaiheessa tutkimme titaanidioksidirakenteiden valon absorptiokaistan laajentamista lisätyllä rautaoksidipinnoitekerroksella. Rautaoksidipinnoitteella onnistuttiin kasvattamaan valon absorptiota, jolla saavutettiin suurempi valokemiallisten kennojen virta. Titaani- ja rautaoksidien havaittiin sekoittuvan keskenään valmistusprosessin aikana, minkä todettiin olevan välttämätöntä kennon toiminnan kannalta.&#13;\n &#13;\nTämän väitöskirjatyön tulokset osoittavat, että yhdistämällä selluloosamuottitekniikan ja atomikerroskasvatuksen voidaan valmistaa materiaaleja hiilidioksidivapaan energiantuotannon sovelluksiin. Näiden tulosten valossa uskomme, että yhä kehittyvillä ALD-tekniikoilla sekä uusilla nanoselluloosamateriaaleilla on mahdollista valmistaa entistä tehokkaampia materiaaleja ilmastotavoitteiden saavuttamiseksi. Photovoltaic system ; Template ; Porosity ; Materials science ; Layer (electronics) ; Atomic layer deposition ; Cellulose ; Metal ; Nanotechnology ; Chemical engineering ; Metallurgy ; Composite material ; Engineering ; Electrical engineering Electron and X-Ray Spectroscopy Techniques ; TiO2 Photocatalysis and Solar Cells
Authors: Jonas Wolfs
Source: MPG.PuRe (Max Planck Society) (article, 2020-01-01)
Field: Materials Science — Biomaterials

Accelerated degradation of poly(lactic acid) in seawater Plastic materials shape our life, but they have been identified as a major pollutant of the oceans due to their long persistency and low degradability.Poly(lactic acid) (PLA) is one of the most promising biodegradable plastic alternatives because of its cheap, scalable and sustainable production from renewable resources.However, PLA is only degraded in reasonable half-life times in industrial compost sites and has turned out to be non-degradable in seawater. [1][2]][4] Therefore, this master thesis focused on the development of seawater degradable PLA by precisely installing phosphate moieties into the polymer backbone, which degrade on-demand upon a specific trigger.Different five-membered cyclic phosphate monomers with a protected hydroxyethyl side-chain were synthesized and copolymerized with lactide using an organocatalytic ring-opening polymerization.A statistical copolymerization was found to yield gradient copolymers with a block-like structure of lactic acid units followed by a block-like structure of phosphate units.To synthesize PLA with single phosphate units in defined intervals, evenly distributed over the polymer chain, the copolymerization kinetics were studied using in situ 1 H and 31 P NMR methods.A novel one-pot setup was developed with a continuous polymerization of the phosphate monomer and multiple sequential additions of lactide in precisely calculated time intervals to achieve the desired polymer architecture.The thermal properties (Tg and Tm)were proven to differ only to a small extent and the Td even increased significantly compared to PLA homopolymers (DSC, TGA).By varying the phosphate breaking point content, a tailorable hydrolytic degradation in seawater with degradation times between 14 days and 3.3 years (instead of 10.5-35.4 years for PLA homopolymer) was proven by a reduction of molecular weight (SEC, 1 H NMR) and the formation of monomeric lactic acid ( 1 H NMR, enzymatic assay/UV-Vis spectroscopy). Seawater ; Degradation (telecommunications) ; Lactic acid ; Chemistry ; Bacteria ; Biology ; Computer science ; Ecology biodegradable polymer synthesis and properties ; Biopolymer Synthesis and Applications ; Microplastics and Plastic Pollution
Authors: Muhammad Sohail Ahmad
Source: Institutional Repositories DataBase (IRDB) (article, 2020-09-25)
Field: Materials Science — Materials Chemistry

Functionalization of nanocarbons and application for catalysis Catalysts are widely used in organic synthesis, environmental protection, and energy-related systems.The conventional catalysts are composed of noble transition metals or their oxides.The activity and selectivity of the metal catalysts can be tuned by modification of their ligands, and support materials, and numerous metal-based catalysts have been developed and used in diverse reactions.However, the transition metal-catalyzed reactions still have limitations due to the inherent drawbacks of the systems.Firstly, metal-based catalysts are generally expensive because of the high cost of transition metals, ligands, and support materials.Secondly, these metals are toxic and difficult to remove the trace amounts of residues from the products, which is problematic in the field of pharmaceuticals and electronic devices.Thirdly, some of the transition metal catalysts are very sensitive to moisture and oxygen; thus, special environment and techniques are needed.Finally, sometimes co-catalysts/additives are required to initiate the reactions and enhance the selectivity of the products.To address these problems, recently, nanocarbons have been widely explored to replace conventional metal-based catalysts.In chapter 1, an introductory section, presents the background of this research and general consideration of state of the art in the field of carbocatalysis, focusing on active sites and applications for organic reactions.Initially, the carbon-based catalysts were applied for the functional group transformations, such as oxidation and esterification reactions.Recently, they have been used for the construction of C-C bonds, which are fundamental reactions in the synthesis of fine chemicals, medicinal and pharmaceutical agents, agrochemicals, and organic electronics materials; however, these reactions are performed under metal-based catalytic systems.Therefore, catalysts from sustainable materials, such as carbon, could replace the transition metalbased catalytic systems.Graphene-based materials have large surface area and a 2D morphology making accessible most of the atoms that make these materials suitable as a catalyst, and the structure of graphene is tunable by chemical treatment.This is one of the reasons why there is growing interest in exploring the potential of graphene-based materials as heterogeneous catalysts.Carbon materials as a catalyst have been developed since over 100 year ago, but it has not been mainstream materials due to the low activity.On the other hand, recent advantages of reliable and well-established production of graphene have motivated researchers to study carbocatalysts. Surface modification ; Catalysis ; Nanotechnology ; Materials science ; Chemistry ; Chemical engineering ; Engineering ; Organic chemistry Catalytic Processes in Materials Science
Authors: Mohamad Widodo | Sophie Anggitta Raharjani
Source: Arena Tekstil (article, 2020-06-30)
Field: Chemistry — Organic Chemistry

STRUCTURE-ACTIVITY RELATIONSHIPS AND SURFACE IMMOBILIZATION OF POLYCATIONIC ANTIMICROBIALS Antimicrobial agents have been the subject of scientific interest for the last few decades. However, the emergence of a novel coronavirus and pandemic that ensued has brought a new sense of urgency to the field of antibacterial research. The most urgent needs to mitigate the pandemic are self-disinfecting health equipment and antimicrobial protective equipment such as gowns for healthcare workers and face masks for the general public. At a time of high demand for antimicrobial products, understanding the mechanisms involved in antimicrobial polymers will be a benefit. In this review, the definition of antimicrobials and their classification according to the mode of action, as well as their chemical structure, were explained and used to build the fundamental understanding about antimicrobials and the working principles behind their action. The discussion continued with factors that affect the antimicrobial activity, which is the focus of the review. The first part of the review deals with free antimicrobial polymers in solution. The effect of molecular weight, counterions, spacer length and alkyl chain to the efficacy of antimicrobial polymers are highlighted and discussed at length. Focus in the second part shifts towards surface-immobilized antimicrobial polymers and their methods of immobilization. Antimicrobial ; Nanotechnology ; Counterion ; Chemistry ; Materials science ; Organic chemistry Antimicrobial agents and applications ; Antimicrobial Peptides and Activities ; Pharmaceutical and Antibiotic Environmental Impacts
Authors: Lucie Motyčková
Source: Brno University of Technology Digital Library (Brno University of Technology) (article, 2020-07-14)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Magnetické vlastnosti samouspořádaných nanomagnetů FeRh Magnetické nanočástice a nanostrukturované materiály jsou velkým příslibem v mnoha oblastech, včetně biomedicíny, sanace životního prostředí nebo získávání energie. Proto neustále roste zájem o výzkum jejich jedinečných vlastností a vývoj uskutečnitelných výrobních postupů. Tato práce se zabývá metodou samouspořádávání, spočívající v povrchové precipitaci tenkých vrstev, za účelem výroby epitaxních polí nanoostrůvků ze slitiny FeRh na různých monokrystalických substrátech. Při tomto výrobním postupu zůstává zachována metamagnetická fázová přeměna nanoostrůvků. Morfologie a magnetické vlastnosti samouspořádaných nanomagnetů z FeRh jsou charakterizovány kombinací experimentálních technik a modelování, přičemž bylo zjištěno, že jejich rovnovážné tvary a magnetické uspořádání jsou navzájem propojeny. Kromě toho je navržena cesta pro získání volných nanočástic, která by mohla potenciálně umožnit využití metamagnetických nanostruktur v buněčných kulturách a biomedicíně obecně. Za tímto účelem jsou nanoostrůvky FeRh uvolňovány ze substrátu chemickým leptáním. Chování nanočástic a jejich reakce na teplotu a magnetické pole jsou studovány v kapalném prostředí. Metamagnetické vlastnosti separovaných nanočástic jsou charakterizovány pomocí vibrační magnetometrie. Nanomagnet ; Medicine ; Physics Magnetic Properties of Alloys ; Electromagnetic wave absorption materials
Authors: David Cornil | Nicolas Rivolta | V. Mercier | H. Wiame | David Beljonne | Jérôme Cornil
Source: ORBi UMONS (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

How to Enhance the Adhesion Energy at Oxide/Ag Interfaces in Low-Emissivity Glasses: A Theoretical Insight into Doping and Vacancy Effects peer reviewed Doping ; Vacancy defect ; Adhesion ; Energy (signal processing) Copper-based nanomaterials and applications ; Transition Metal Oxide Nanomaterials ; Electron and X-Ray Spectroscopy Techniques