jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Ian C. Chagunda | Peter J. H. Williams | Tiago Fisher | Naomi L. Stock | Daniel G. Beach | Gilian T. Thomas | Jane Zhu | J. Scott McIndoe
Source: ChemRxiv (preprint, 2024-01-30)
Field: Chemistry — Spectroscopy

How soft is your ESI-MS anyway? Electrospray ionization mass spectrometry (ESI-MS) is a powerful tool for identifying and characterizing organometallic and coordination compounds. However, detection of fragile structures bound by weaker intermolecular forces can be significantly limited in ESI-MS owing to the use of relatively harsh instrument conditions and configurations. In this study, a set of tests was developed to assess the softness of ESI-MS systems. Two variants are presented: positive ion mode, utilizing a mixture of sodium ions and triphenylphosphine oxide producing [Na(OPPh3)n]+ ions (n = 1-4), and negative ion mode utilizing Pd(PPh3)4 and sulfonated triphenylphosphine producing [Pd(L)(PPh3)n]– ions (n = 0-2), where softer instrument conditions preserve a higher proportion of the high-coordinate ions and harsher conditions will result in increased detection of products of ion fragmentation. The results revealed notable variations in instrument softness, which were influenced by a combination of instrument design and experimental parameters. Meticulously optimizing experimental conditions and ESI-MS parameters is essential to achieving the softest ionization possible, ensuring reliable analysis where applicable. This study offers valuable insight through straightforward tests that can be employed to assess the suitability of an instrument for specific research needs. Business Mass Spectrometry Techniques and Applications ; Analytical chemistry methods development ; Advanced Chemical Sensor Technologies
Authors: Gregory R. Alvey | Andrey Shatskiy | Elena V. Stepanova | Lucas Kusch | Moritz Schepp | Till L. Kalkuhl | Marco Bormetti | Chang Ho Lee | Ludwig Wåhlin | Markus D. Kärkäs
Source: ChemRxiv (preprint, 2024-04-05)
Field: Chemistry — Organic Chemistry

Exploiting Photoredox Catalysis for Rapid Access to Unnatural α-Amino Acids through α-Amino C–H Bond Activation Unnatural amino acids (UAAs) have shown great potential to enhance the pharmacological properties of peptides and represent a key motif in a wide range of biologically relevant natural products. Herein, we disclose a protocol that facilitates the asymmetric synthesis of UAAs from widely abundant amines through photoredox-mediated α-amino C–H bond activation. The platform utilizes either the strongly oxidizing organic acridinium or decatungstate as a photocatalyst to generate α-amino radicals from a variety of amines, which are then effectively coupled with a chiral glyoxylate-derived N-sulfinyl imine. The disclosed platform provides a general entry to various decorated unnatural α-amino acid derivatives, accommodating a diverse array of functional groups. Photoredox catalysis ; Amino acid ; Chemistry ; Catalysis ; Combinatorial chemistry ; Stereochemistry ; Biochemistry ; Photocatalysis Catalytic C–H Functionalization Methods ; Synthesis and Catalytic Reactions ; Radical Photochemical Reactions
Authors: Margarita Angel Alvarez | Nathan Black | Saylor Estelle Blanco | K R Reid | Eugene J. Billiot | Fereshteh H. Billiot | Kevin Morris
Source: Molecules (article, 2024-09-18)
Field: Chemistry — Organic Chemistry

Influence of Linear Diamine Counterions on the Self-Assembly of Glycine-, Alanine-, Valine-, and Leucine-Based Amphiphiles Electrical conductimetry and dynamic light scattering (DLS) were used to investigate the aggregation behaviors of four amino acid-based surfactants (AABSs; undecanoyl-glycine, undecanoyl-<i>l</i>-alanine, undecanoyl-<i>l</i>-valine, undecanoyl-<i>l</i>-leucine) in the presence of five linear diamine counterions (1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane). Electrical conductimetry was used to measure the CMCs for each system, which ranged from 5.1 to 22.5 mM. With respect to counterions, the obtained CMCs decreased with increases in the interamine spacer length; this was attributed to the improved torsional binding flexibility in longer counterions. Strong linear correlations (mean R<sup>2</sup> = 0.9443) were observed between the CMCs and predicted surfactant partition coefficients (logP; water/octanol), suggesting that micellization is primarily driven by the AABS's hydrophobicity for these systems. However, significant deviations in this linear relationship were observed for systems containing 1,2-diaminoethane, 1,4-diaminobutane, and 1,6-diaminohexane (<i>p</i> = 0.0774), suggesting altered binding dynamics for these counterions. pH measurements during the CMC determination experiments indicated the full deprotonation of the AABSs but did not give clear insights into the counterion protonation states, thus yielding an inconclusive evaluation of their charge stabilization effects during binding. However, DLS measurements revealed that the micellar size remained largely independent of the counterion length for counterions longer than 1,2-diaminoethane, with hydrodynamic diameters ranging from 2.2 to 2.8 nm. This was explained by the formation of charge-stabilized noncovalent dimers, with each counterion bearing a full +2 charge. Conductimetry-based estimates of the degrees of counterion binding (β) and free energies of micellization (ΔG°<sub>M</sub>) revealed that bulky AABSs exhibit preferential binding to counterions with an even number of methylene groups. It is proposed that when these counterions form noncovalent dimers, perturbations in their natural geometries result in the formation of a binding pocket that accommodates the AABS steric bulk. While the direct application of these systems remains to be seen, this study provides valuable insights into the structure-property relationships that govern AABS aggregation. Counterion ; Chemistry ; Valine ; Alanine ; Diamine ; Pulmonary surfactant ; Protonation ; Deprotonation ; Organic chemistry ; Ion ; Amino acid Surfactants and Colloidal Systems ; Molecular Sensors and Ion Detection ; Lipid Membrane Structure and Behavior
Authors: Gergő Dániel Tóth | Zsófia Molnár | Gábor Koplányi | Benjámin Gyarmati | András Szilágyi | Gábor Katona | Alfréd Menyhárd | László Poppe | Béla Pukánszky | Diána Balogh‐Weiser
Source: ChemCatChem (article, 2024-12-17)
Field: Materials Science — Biomaterials

How Could the Physical Properties of Poly(vinyl alcohol) Influence Enzymatic Activity? A Detailed Study on Nanofibrous Catalysts Incorporating a Lipase from <i>Burkholderia cepacia</i> Abstract Utilizing the electrospinning technique to entrap enzymes within nanofibers (providing nanofibrous enzyme catalysts, NEC) offers promising avenues for the scientific and industrial sectors as well. While numerous instances of poly(vinyl alcohol) (PVA)‐based nanofibrous biocatalysts have been documented, a comprehensive investigation to characterize the effect of PVA on catalytic activity is notably lacking. This study systematically investigates the effect of PVA properties, such as molecular weight (24–205 kDa), degree of hydrolysis (DoH, 88% and 98%), and polymer concentration (6–16 wt%), on the structure of PVA nanofibers and on the biocatalytic properties of a lipase from Burkholderia cepacia ( Bc L) entrapped into PVA nanofibers, ensuring 100% yield of immobilization. The PVA‐enzyme interactions were studied using viscometry, scanning electron microscopy, Raman mapping, differential scanning calorimetry, and computational docking simulations. Stereoselective hydrolysis and transesterification were used to evaluate enzyme activity. Results showed that the molecular weight and DoH of PVA have a significant effect on the biocatalytic activity of nanofibrous enzyme catalysts. Remarkably, activity yields (mostly exceeded 100%, with maximal yields achieved using fully hydrolyzed PVA) with a molecular weight of 61 kDa provided a 10‐fold increase in the specific enzymatic activity of Bc L immobilized in nanofibers (90.6 U × g −1 ) compared to its native form (9.0 U × g −1 ). Vinyl alcohol ; Lipase ; Nanofiber ; Hydrolysis ; Chemistry ; Differential scanning calorimetry ; Catalysis ; Polyester ; Electrospinning ; Enzymatic hydrolysis ; Polymer ; Organic chemistry ; Materials science ; Polymer chemistry ; Chemical engineering ; Enzyme ; Nanotechnology Electrospun Nanofibers in Biomedical Applications ; Enzyme Catalysis and Immobilization ; Electrochemical sensors and biosensors
Authors: I.I. Ajibade | B. Garba | Paiman Suriati
Source: Ife Journal of Science (review, 2024-04-25)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Advancing supercapacitor performance: a comprehensive review of electrochemical conversion of coconut shells into activated carbon nanofibers This assessment provides a comprehensive evaluation of the limitations associated with the application of supercapacitors, along with the imperative to enhance their functionality. Following this, the advantages of Electrochemical Double Layer Capacitors (EDLC) are discussed in comparison to other types utilized in supercapacitor contexts. The transformation of coconut shells into carbon nanofibers is extensively investigated through various methodologies, highlighting both their benefits and limitations. It becomes evident that the current utilization of coconut shells has not yet achieved optimal sustainability or viability for energy storage purposes. Nevertheless, coconut shells offer a widely available and sustainable resource that can be converted into Activated Carbon nanofibers for energy storage applications. Diverse techniques have been employed to produce these ACB nanofibers, each targeting specific objectives including improved energy density, adaptable diameter, reduced energy consumption, and faster charging times. Despite these accomplishments, it is evident that numerous significant properties of carbon nanofibers derived from coconut shells remain unexplored, leading to substantial knowledge gaps that must be addressed for each technique. Therefore, further research is warranted to advance the comprehension of key parameters associated with various methods, ultimately facilitating the development of highly desirable carbon nanofibers sourced from coconut shells and catering to the requirements of sustainable energy storage applications. Supercapacitor ; Activated carbon ; Materials science ; Carbon nanofiber ; Nanofiber ; Electrochemistry ; Nanotechnology ; Business ; Electrode ; Chemistry ; Carbon nanotube ; Organic chemistry Supercapacitor Materials and Fabrication ; Electrospun Nanofibers in Biomedical Applications ; Biodiesel Production and Applications
Authors: Yohan Gisbert | Pablo Simón Marqués | Caterina Baccini | Seifallah Abid | Nathalie Saffon‐Merceron | Gwénaël Rapenne | Claire Kammerer
Source: ChemRxiv (preprint, 2024-01-22)
Field: Chemistry — Organic Chemistry

Copper-Catalyzed Perarylation of Cyclopentadiene: Synthesis of Hexaarylcyclopentadienes While hexaphenylsilacyclopentadiene (hexaphenylsilole) is viewed as an archetypal Aggregation-Induced Emission (AIE) luminogen, its isostructural hydrocarbon surrogate hexaphenylcyclopentadiene has strikingly never been investigated in this context, most probably due to a lack of synthetic availability. Herein, we report a straightforward synthesis of hexaphenylcyclopentadiene, via the direct perarylation of cyclopentadiene upon copper(I) catalysis under microwave activation, with the formation of six new C-C bonds in a single synthetic operation. Using zirconocene dichloride as a convenient source of cyclopentadiene and a variety of aryl iodides as coupling partners, this copper-catalyzed cross-coupling reaction gave rise to a series of unprecedented hexaarylcyclopentadienes, displaying promising properties as AIE luminogens. In addition, these propeller-shaped perarylcyclopentadienes are direct precursors of π-extended conjugated polycyclic compounds, and their cyclodehydrogenation under Scholl reaction conditions yielded helicenic 17,17-diarylcyclopenta[l,l’]diphenanthrenes. These structurally complex polyannelated fluorene derivatives can now be prepared in only two synthetic steps from cyclopentadiene for applications as organic semiconductors or fluorophores. Cyclopentadiene ; Chemistry ; Catalysis ; Aryl ; Context (archaeology) ; Conjugated system ; Fluorene ; Isostructural ; Copper ; Combinatorial chemistry ; Coupling reaction ; Photochemistry ; Organic chemistry ; Polymer ; Crystal structure Catalytic Cross-Coupling Reactions ; Synthesis and Properties of Aromatic Compounds ; Synthesis and Reactivity of Heterocycles
Authors: Justina Gaidukevič | Jurgis Barkauskas
Source: Crystals (article, 2024-08-29)
Field: Materials Science — Materials Chemistry

Advanced Technologies in Graphene-Based Materials Graphene-based materials, including single layer graphene, laser-induced graphene, carbon nanotubes, graphene oxide, and reduced graphene oxide, have become cornerstones of modern materials science due to their exceptional properties and wide range of potential applications [...] Graphene ; Nanotechnology ; Materials science ; Computer science Graphene research and applications ; Graphene and Nanomaterials Applications ; Supercapacitor Materials and Fabrication
Authors: László Óvári | Gábor Vári | M. Farkas | Gyula Halasi | Nikolett Oláh | Csaba Vass | A.P. Farkas | András Berkó | János Kiss | Zoltán Kónya
Source: Surface Science (article, 2024-10-24)
Field: Materials Science — Materials Chemistry

Fabrication of B-C-N nanosheets on Rh(111) from benzene – borazine mixtures • B-C-N monolayers were prepared on Rh(111) from borazine and benzene • Mixed honeycomb BCN layer was formed at an optimal benzene–borazine ratio • XPS revealed the intimate mixing of B, C, and N atoms realized mostly via B-C bonds • According to STS measurements, the obtained BCN monolayer is semiconducting Atomic level studies of solid state surfaces performed in ultra-high vacuum (UHV) had already an energetic 15–20 years past when our research group in Szeged started working in this field in mid 1970s. Till then several very important methods had been developed, like UHV technology, commercially available electron and photoelectron spectroscopy techniques, etc. Characterization of metal and semiconductor (oxide) surfaces and their adsorption properties had already been widely studied. In any case, the last 40–50 years also witnessed great discoveries and exciting new techniques. Considering only the activity related to heterogeneous catalysis, the main focus of our research group, new breakthrough methods emerged like HREELS, RAIRS, SPM, NAPXPS, EXAFS, NEXAFS. Along this path, new experimental and theoretical approaches appeared like planar model catalysts and inverse catalysts, atomic level investigation and understanding of surface diffusion-controlled phenomena (particle growth and disruption, strong metal-support interaction (SMSI), decoration, spillover), atomic level identification of active sites, self-organized nano-systems, surface alloys and nanotemplates. It was great to participate in this magical activity for more than 50 years. Both internationally and locally in Szeged, in the last two decades, surface science has opened to the wide world of 2D materials like the semimetal graphene and the insulator hexagonal boron nitride. However, the formation of a mixed layer of C, B and N proved to be a difficult task due to the primary tendency for phase separation. In the present work, we report on a preparation method of honeycomb “BCN” materials on Rh(111) by using benzene/borazine mixtures as precursors. It was demonstrated that by a suitable choice of the growth parameters, the formation of large, separated graphene and h-BN islands can be avoided. Borazine ; Fabrication ; Benzene ; Materials science ; Chemistry ; Nanotechnology ; Chemical engineering ; Organic chemistry ; Engineering Graphene research and applications ; Boron and Carbon Nanomaterials Research ; Diamond and Carbon-based Materials Research
Authors: Giada Moroni | Elena Bombonato | Samuele Bonafè | Alessandro Di Michele | Sara Presenti | Sara Guariento | Massimo Marcaccio | Roccaldo Sardella | Paolo Ronchi | Antimo Gioiello
Source: ChemCatChem (article, 2024-02-12)
Field: Chemistry — Organic Chemistry

Investigating the Catalytic Efficiency of Supported NHC‐Ag(I) Complexes in the Borono‐Minisci Reaction Abstract A series of supported N ‐heterocyclic carbene silver complexes (NHC‐Ag(I)) were prepared and characterized as catalysts for the borono‐Minisci reaction. After characterization, the synthesized catalysts were evaluated in batch mode to determine the reaction performance and kinetics. Interestingly, cyclic voltammetric analysis showed that the structure of both the complex and the ligand significantly influences the Ag(I)/Ag(II) redox potential and, in turn, the catalytic efficiency. Among the tested catalysts, the Si‐supported NHC‐Ag(I) 6 afforded the desired products in good to excellent yields in only 15 min, providing a complementary tactic to standard homogeneous approaches. Catalysis ; Carbene ; Homogeneous ; Redox ; Chemistry ; Ligand (biochemistry) ; Kinetics ; Catalytic efficiency ; Combinatorial chemistry ; Organic chemistry N-Heterocyclic Carbenes in Organic and Inorganic Chemistry ; Catalytic Cross-Coupling Reactions ; Synthetic Organic Chemistry Methods
Authors: Yuan Zhao | Runhua Chen | Jingchen Luo | Juncheng Zhu | Yang Wu | Panzhe Qiao | Wensheng Yan | Yang Pan | Junfa Zhu | Xiaolong Zu | Yongfu Sun
Source: ChemPhysChem (article, 2024-01-09)
Field: Chemistry — Inorganic Chemistry

Selective CO<sub>2</sub> Photoreduction Enabled by Water‐stable Cu‐based Metal‐organic Framework Nanoribbons The goal of photocatalytic CO<sub>2</sub> reduction system is to achieve near 100 % selectivity for the desirable product with reasonably high yield and stability. Here, two-dimensional metal-organic frameworks are constructed with abundant and uniform monometallic active sites, aiming to be an emerged platform for efficient and selective CO<sub>2</sub> reduction. As an example, water-stable Cu-based metal-organic framework nanoribbons with coordinatively unsaturated single CuII sites are first fabricated, evidenced by X-ray diffraction patterns and X-ray absorption spectroscopy. In situ Fourier-transform infrared spectra and Gibbs free energy calculations unravel the formation of the key intermediate COOH* and CO* is an exothermic and spontaneous process, whereas the competitive hydrogen evolution reaction is endothermic and non-spontaneous, which accounts for the selective CO<sub>2</sub> reduction. As a result, in an aqueous solution containing 1 mol L<sup>-1</sup> KHCO<sub>3</sub> and without any sacrifice reagent, the water-stable Cu-based metal-organic framework nanoribbons exhibited an average CO yield of 82 μmol g<sup>-1</sup> h<sup>-1</sup> with the selectivity up to 97 % during 72 h cycling test, which is comparable to other reported photocatalysts under similar conditions. Endothermic process ; Chemistry ; Aqueous solution ; Exothermic reaction ; Selectivity ; Yield (engineering) ; Metal-organic framework ; Fourier transform infrared spectroscopy ; Gibbs free energy ; Reagent ; Inorganic chemistry ; Infrared spectroscopy ; Metal ; Materials science ; Physical chemistry ; Chemical engineering ; Catalysis ; Organic chemistry ; Adsorption ; Thermodynamics Metal-Organic Frameworks: Synthesis and Applications ; Advanced Photocatalysis Techniques ; Carbon dioxide utilization in catalysis
Authors: Samuel Mckeating | Oliver B. Penrhyn-Lowe | Sean Flynn | Savannah R. Cassin | Sarah L. Lomas | Christopher Fidge | Paul J. Price | Stephen W. Wright | Pierre Chambon | Steve P. Rannard
Source: Communications Chemistry (article, 2024-09-03)
Field: Chemistry — Organic Chemistry

Controlling enzyme hydrolysis of branched polymers synthesised using transfer-dominated branching radical telomerisation via telogen and taxogen selection With the ever-growing reliance on polymeric materials for numerous applications, new avenues to induce, design and control degradation are clearly important. Here, we describe a previously unreported approach to controlling enzymatic hydrolysis of high molecular weight branched polymers formed from the new free-radical polymer synthesis strategy transfer-dominated branching radical telomerisation (TBRT). Modifying the chemical nature of TBRT polymers may be accomplished through telogen selection and multi-vinyl taxogen (MVT) design, and we show telogen-driven control of enzyme-catalysed hydrolysis and the impact of careful placement of hydrolytically susceptible groups within readily synthesised MVTs. Our results indicate that utilising conventional free-radical chemistries and unsaturated monomers as feedstocks for highly branched polymer architectures has considerable potential for the design of future materials that degrade into very low molecular weight byproducts at variable and controllable rates. Branching (polymer chemistry) ; Polymer ; Monomer ; Hydrolysis ; Chemistry ; Organic chemistry ; Polymer chemistry ; Materials science Advanced Polymer Synthesis and Characterization ; Microplastics and Plastic Pollution ; biodegradable polymer synthesis and properties
Authors: Arpine Vardanyan | Jonas Polkaehn | M. Bauder | Alexander Villinger | Peter Ehlers | Peter Langer
Source: Organic & Biomolecular Chemistry (article, 2024-01-01)
Field: Chemistry — Organic Chemistry

Synthesis and properties of thienonaphtho[<i>bc</i>]pyridines and thienonaphtho[<i>bc</i>]quinolines The incorporation of heteroatoms within polycyclic aromatic compounds has gained significant interest due to its potential to effectively alter the inherent physicochemical properties of compounds without the need for profound structural changes. We herein report the development of a modular synthesis of hitherto unknown thienonaphtho[<i>bc</i>]pyridines and thienonaphtho[<i>bc</i>]quinolines in very good yields by Brønsted acid mediated cycloisomerization, permitting selective access to two isomeric products that are isoelectronic to the parent dibenzopyrene. The photophysical and electrochemical properties of the desired compounds were extensively studied and further complemented by DFT calculations. Electrochemistry ; Chemistry ; Combinatorial chemistry ; Medicinal chemistry ; Physical chemistry ; Electrode Organic Chemistry Cycloaddition Reactions ; Synthesis and Reactivity of Heterocycles ; Synthesis and Properties of Aromatic Compounds