jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Ahmed Badreldin | Khaled Elsaid | Wubulikasimu Yiming | Karim H. Youssef | Zafar Khan Ghouri | Abdellatif El Ghenymy | Dharmesh Kumar | Ahmed Abdala | Ahmed Abdel‐Wahab
Source: ACS Applied Nano Materials (article, 2022-09-23)
Field: Materials Science — Materials Chemistry

Direct Thermochemical CO<sub>2</sub> Reduction to Reduced Graphene Oxide-like Nanomaterials: Implications for Environmental and Energy Storage and Conversion Applications CO2 capture and conversion to value-added products have seen continued advancement in recent years through electrochemical and thermochemical routes. In this work, we have adapted a facile and potentially scalable thermochemical reduction technique that directly reduces CO2 to different-quality reduced graphene oxide (rGO) solids. Several characterization techniques have been undertaken to investigate the role of two- and three-dimensional copper catalytic substrates, reaction time, and CO2 humidity content on the characteristics of the prepared rGO. Growth for 1 h at 550 °C atop a uniform two-dimensional (2D) catalytic copper substrate under a humidified CO2 environment (0.14 gH2O/gCO2) attained rGO with low defect densities (0.36 × 1011 cm–2) and high domain (31.9 nm) and crystallite (3.32 nm) sizes. Detailed statistical Raman analyses over large areas confirm that the mean defect distance of the synthesized rGO samples is 16–20 nm, indicative of the intrinsic high quality attained. The degree of reduction in rGO based on C/O ratios from 4 to 8 suggests that operating conditions can be fine-tuned to attain different-quality rGO with different attributable macroproperties such as conductivity and hydrophilicity. The developed method of direct CO2 reduction to rGO can be further tuned to produce different quality, morphology, and yield of other high-value solid carbon-based materials for emerging and existing applications. Graphene ; Materials science ; Oxide ; Crystallite ; Chemical engineering ; Raman spectroscopy ; Nanomaterials ; Catalysis ; Nanotechnology ; Carbon fibers ; Substrate (aquarium) ; Metallurgy ; Chemistry ; Composite material ; Composite number Graphene research and applications ; Supercapacitor Materials and Fabrication ; Advancements in Battery Materials
Authors: Shreyas Kuddannaya | Wei Zhu | Jeff W. M. Bulte
Source: Methods in molecular biology (article, 2022-01-01)
Field: Materials Science — Materials Chemistry

In Vivo Imaging of Implanted Hyaluronic Acid Hydrogel Biodegradation Self-healing hydrogels ; Hyaluronic acid ; In vivo ; Ethylene glycol ; Biomedical engineering ; Transplantation ; Magnetic resonance imaging ; Materials science ; Chemistry ; Surgery ; Medicine ; Anatomy ; Polymer chemistry Lanthanide and Transition Metal Complexes ; Advanced MRI Techniques and Applications ; Electron Spin Resonance Studies
Authors: Karoline Kvande | Sebastian Prodinger | Fabian Schlimpen | Pablo Beato | Patrick Pale | Stefan Chassaing | Stian Svelle
Source: Topics in Catalysis (article, 2022-12-27)
Field: Materials Science — Materials Chemistry

Copper-zeolites Prepared by Solid-state Ion Exchange - Characterization and Evaluation for the Direct Conversion of Methane to Methanol Abstract Direct conversion of methane to methanol (MTM) over Cu-zeolites is a so-called “dream reaction” for the chemical industry. There is still a lot that can be done in order to optimize the reaction by e.g. achieving a deeper understanding of the reaction mechanism and the nature of the Cu-sites. In this study, we investigated a solid-state ion exchange method to incorporate Cu I ions into zeolites (MOR, BEA, ZSM-5 and FAU), as a more scalable technique. The solid-state ion exchange led to a Cu/Al ration of about 0.8, however with a heterogeneous distribution of Cu. Regardless, Fourier transform-infrared spectroscopy still revealed that most Brønsted acid sites were exchanged in all four samples. Further, CH 4 -temperature programmed reaction experiments showed that some Cu-sites formed were reactive towards CH 4 , with Cu I -MOR and Cu I -FAU having the largest CH 4 consumption. Ultimately, the Cu I -zeolites were tested in the MTM reaction and proved capable of producing methanol, even without the presence of Brønsted sites. A MOR with lower Cu/Al ratio (0.30) was also tested for comparison, and as this sample obtained a much higher productivity than the Cu I -MOR with high Cu-loading (0.10 vs. 0.03 mol MeOH /mol Cu ), it was demonstrated that some fine-tuning is necessary to obtain the active Cu sites for methane activation. Methanol ; Catalysis ; Chemistry ; Ion exchange ; Copper ; Methane ; Zeolite ; Inorganic chemistry ; Fourier transform infrared spectroscopy ; Ion ; Chemical engineering ; Organic chemistry Catalytic Processes in Materials Science ; Catalysts for Methane Reforming ; Catalysis and Oxidation Reactions
Authors: Zhaoye Lv | Jun Hou | Junjie Yao | Ye Yuan | Yulan Qian | Junyang Zhu | Hongjuan Zhao | Xiaoqing Xiong | Cheng‐Qi Jiao
Source: RSC Advances (article, 2022-01-01)
Field: Materials Science — Materials Chemistry

Investigation on fluorescein derivatives with thermally activated delayed fluorescence and their applications in imaging Fluorescein derivatives with thermally activated delayed fluorescence (TADF) show much stronger competition ability and vaster prospects than traditional fluorescein dyes due to their prominent long lifetime. It will be of great significance to synthesize more fluorescein derivatives with TADF. In this work, compounds DCF-MPYA and FL with TADF properties were obtained by fine tuning the substituents' structure on the basis of fluorescein derivative DCF-MPYM. Their long-lived triplet excited states (21.78 μs, 32.0 μs) were proved by nanosecond time-resolved transient difference absorption spectra. The steady-state and time-resolved fluorescence spectra showed that DCF-MPYA and FL exhibited red fluorescence around 645 nm and 651 nm, respectively. The results of sensitivity to oxygen and heavy atoms further demonstrated that the time-resolved fluorescence spectra originate from the delayed fluorescence. The time correlated single-photon counting (TCSPC) data indicated that DCF-MPYA and FL showed long-lived lifetimes of 13.16 μs and 23.72 μs, respectively. The energy gap (Δ<i>E</i> <sub>ST</sub>) between the singlet (S<sub>1</sub>) and triplet (T<sub>1</sub>) states of DCF-MPYA and FL was calculated to be 3.32 meV and 9.98 meV from the decay rate of DF as a function of temperature. The small energy gap is conducive to the occurrence of efficient TADF at room temperature. Meanwhile, Gaussian calculation was employed to observe the electron density of DCF-MPYA and FL in the ground and excited states. The calculation results indicate that the shapes and energy levels of the highest occupied molecular orbitals (HOMOs), lowest unoccupied molecular orbitals (LUMOs), and LUMOs+1 for the monoanion and dianion forms are similar and thus DCF-MPYA and FL exhibit almost the same luminescence properties. Finally, DCF-MPYA and FL with low toxicity were used in confocal and time-resolved fluorescence imaging. Our construction strategy will be beneficial for developing more fluorescein derivatives with TADF in the future. Fluorescence ; Fluorescein ; Chemistry ; Fluorescence-lifetime imaging microscopy ; Photochemistry ; Optics ; Physics Luminescence and Fluorescent Materials ; Organic Light-Emitting Diodes Research ; Photoreceptor and optogenetics research
Authors: Lorenz Rösler | Mark V. Höfler | Hergen Breitzke | Till Wissel | Kevin Herr | Henrike Heise | Torsten Gutmann | Gerd Buntkowsky
Source: Cellulose (article, 2022-06-11)
Field: Chemistry — Organic Chemistry

Dirhodium complex immobilization on modified cellulose for highly selective heterogeneous cyclopropanation reactions Abstract A novel, efficient approach for the functionalization of microcrystalline cellulose (MCC) is presented. The as-obtained material allows the immobilization of chiral dirhodium catalysts preserving their enantioselectivity in asymmetric cyclopropanation reactions. As model, microcrystalline cellulose is modified with a polyethylene glycol derived linker, and Rh 2 ( S -DOSP) 4 is grafted on the material to produce a heterogeneous catalyst. SEM images at different stages of the immobilization show an unchanging uniform morphology, providing constantly good separation characteristics. The modification of the cellulose material with the polyethylene derived linker and the immobilization process are monitored using DNP enhanced 1 H → 13 C CP MAS NMR, quantitative 19 F MAS NMR, TGA and ICP-OES analysis, confirming the success of the immobilization as well as the stability of bonds between the used linker molecule and the cellulose material. Finally, the evaluation of the produced catalyst is demonstrated in the asymmetric cyclopropanation reaction between styrene and methyl( E )-2-diazo-4-phenylbut-3-enoate showing excellent enantioselectivity with an ee of nearly 90% over a wide temperature range as well as good recyclability characteristics in four consecutive catalysis cycles. Cyclopropanation ; Microcrystalline cellulose ; Cellulose ; Catalysis ; Surface modification ; Diazo ; Materials science ; Polymer chemistry ; Polyethylene glycol ; Organic chemistry ; Chemical engineering ; Chemistry ; Physical chemistry Cyclopropane Reaction Mechanisms ; Catalysis for Biomass Conversion ; Physics of Superconductivity and Magnetism
Authors: Marek Brezovan | Jana Juráková | Ján Moncóľ | Ľubor Dlháň | Maria Korabik | Ivan Šalitroš | Ján Pavlik | Peter Segľa
Source: Inorganics (article, 2022-08-30)
Field: Chemistry — Inorganic Chemistry

The Role of the Bridge in Single-Ion Magnet Behaviour: Reinvestigation of Cobalt(II) Succinate and Fumarate Coordination Polymers with Nicotinamide Two previously synthesized cobalt(II) coordination polymers; {[Co(μ2-suc)(nia)2(H2O)2]·2H2O}n (suc = succinate(2−), nia = nicotinamide) and [Co(μ2-fum)(nia)2(H2O)2]n (fum = fumarate(2−)) were prepared and thoroughly characterized. Both complexes form 1D coordination chains by bonding of Co(nia)2(H2O)2 units through succinate or fumarate ligands while these chains are further linked through hydrogen bonds to 3D supramolecular networks. The intermolecular interactions of both complexes are quantified using Hirshfeld surface analysis and their infrared spectra, electronic spectra and static magnetic properties are confronted with DFT and state-of-the-art ab-initio calculations. Dynamic magnetic measurements show that both complexes exhibit single-ion magnet behaviour induced by a magnetic field. Since they possess very similar chemical structure, differing only in the rigidity of the bridge between the magnetic centres, this chemical feature is put into context with changes in their magnetic relaxation. Crystallography ; Hydrogen bond ; Supramolecular chemistry ; Intermolecular force ; Chemistry ; Ab initio ; Nicotinamide ; Context (archaeology) ; Cobalt ; Magnetic relaxation ; Infrared spectroscopy ; Materials science ; Inorganic chemistry ; Molecule ; Crystal structure ; Magnetic field ; Magnetization ; Organic chemistry Metal-Organic Frameworks: Synthesis and Applications ; Magnetism in coordination complexes ; Metal complexes synthesis and properties
Authors: Hattie C. Schunk | Mariah J. Austin | Bradley Z. Taha | Matthew S. McClellan | Laura J. Suggs | Adrianne M. Rosales
Source: Molecular Systems Design & Engineering (article, 2022-09-28)
Field: Chemistry — Spectroscopy

Oxidative degradation of sequence-defined peptoid oligomers Due to their N-substitution, peptoids are generally regarded as resistant to biological degradation, such as enzymatic and hydrolytic mechanisms. This stability is an especially attractive feature for therapeutic development and is a selling point of many previous biological studies. However, another key mode of degradation remains to be fully explored, namely oxidative degradation mediated by reactive oxygen and nitrogen species (ROS/RNS). ROS and RNS are biologically relevant in numerous contexts where biomaterials may be present, thus, improving understanding of peptoid oxidative susceptibility is crucial to exploit their full potential in the biomaterials field, where an oxidatively-labile but enzymatically stable molecule can offer attractive properties. Toward this end, we demonstrate a fundamental characterization of sequence-defined peptoid chains in the presence of chemically generated ROS, as compared to ROS-susceptible peptides such as proline and lysine oligomers. Lysine oligomers showed the fastest degradation rates to ROS and the enzyme trypsin. Peptoids degraded in metal catalyzed oxidation conditions at rates on par with poly(prolines), while maintaining resistance to enzymatic degradation. Furthermore, lysine-containing peptide-peptoid hybrid molecules showed tunability in both ROS-mediated and enzyme-mediated degradation, with rates intermediate to lysine and peptoid oligomers. When lysine-mimetic side-chains were incorporated into a peptoid backbone, the rate of degradation matched that of the lysine peptide oligomers, but remained resistant to enzymatic degradation. These results expand understanding of peptoid degradation to oxidative and enzymatic mechanisms, and demonstrate the potential for peptoid incorporation into materials where selectivity towards oxidative degradation is necessary, or directed enzymatic susceptibility is desired. Peptoid ; Sequence (biology) ; Monomer ; Degradation (telecommunications) ; Chemistry ; Oxidative phosphorylation ; Peptide sequence ; Biochemistry ; Peptide ; Organic chemistry ; Computer science ; Polymer ; Gene Molecular Sensors and Ion Detection ; Chemical Synthesis and Analysis ; Antimicrobial Peptides and Activities
Authors: Shiyong Wang | Tomohiko Nishiuchi | Carlo A. Pignedoli | Xuelin Yao | Marco Di Giovannantonio | Yan Zhao | Akimitsu Narita | Xinliang Feng | Kläus Müllen | Pascal Ruffieux | Román Fasel
Source: Quantum Frontiers (article, 2022-12-09)
Field: Materials Science — Materials Chemistry

Steering on-surface reactions through molecular steric hindrance and molecule-substrate van der Waals interactions Abstract On-surface synthesis is a rapidly developing field involving chemical reactions on well-defined solid surfaces to access synthesis of low-dimensional organic nanostructures which cannot be achieved via traditional solution chemistry. On-surface reactions critically depend on a high degree of chemoselectivity in order to achieve an optimum balance between target structure and possible side products. Here, we demonstrate synthesis of graphene nanoribbons with a large unit cell based on steric hindrance-induced complete chemoselectivity as revealed by scanning probe microscopy measurements and density functional theory calculations. Our results disclose that combined molecule-substrate van der Waals interactions and intermolecular steric hindrance promote a selective aryl-aryl coupling, giving rise to high-quality uniform graphene nanostructures. The established coupling strategy has been used to synthesize two types of graphene nanoribbons with different edge topologies inducing a pronounced variation of the electronic energy gaps. The demonstrated chemoselectivity is representative for n-anthryl precursor molecules and may be further exploited to synthesize graphene nanoribbons with novel electronic, topological and magnetic properties with implications for electronic and spintronic applications. Steric effects ; Chemoselectivity ; van der Waals force ; Graphene ; Intermolecular force ; Molecule ; Substrate (aquarium) ; Chemical physics ; Density functional theory ; Graphene nanoribbons ; Nanotechnology ; Materials science ; Computational chemistry ; Chemistry ; Topology (electrical circuits) ; Stereochemistry ; Organic chemistry ; Catalysis Graphene research and applications ; Surface Chemistry and Catalysis ; Molecular Junctions and Nanostructures
Authors: Mónica Andrea Vargas | Lorena Marín | Winny Mónica Castillo | Luis Alfredo Rodríguez | César Magén | Milton Manotas-Albor | J.E. Diosa | Katherine L. Gross
Source: Materials (article, 2022-07-30)
Field: Materials Science — Materials Chemistry

Effect of Ethylene Glycol: Citric Acid Molar Ratio and pH on the Morphology, Vibrational, Optical and Electronic Properties of TiO2 and CuO Powders Synthesized by Pechini Method High-purity TiO<sub>2</sub> and CuO powders were synthesized by the Pechini method, an inexpensive and easy-to-implement procedure to synthetize metal oxides. The variables of synthesis were the ethylene glycol:citric acid molar ratio and the pH. High reproducibility of the anatase and tenorite phase was obtained for all synthesis routes. The degree of purity of the powders was confirmed by XRD, FTIR, UV-Vis absorption and XPS spectra. SEM and TEM images revealed the powders are composed of micrometer grains that can have a spherical shape (only in the TiO<sub>2</sub>) or formed by a non-compacted nanocrystalline conglomerate. FTIR spectra only displayed vibrational modes associating TiO<sub>2</sub> and CuO with nanoparticle behavior. UV-Vis absorption spectra revealed the values of maximum absorbance percentage of both systems are reached in the ultraviolet region, with percentages above 83% throughout the entire visible light spectrum for the CuO system, a relevant result for solar cell applications. Finally, XPS experiments allow the observation of the valence bands and the calculation of the energy bands of all oxides. Ethylene glycol ; Materials science ; Nanocrystalline material ; X-ray photoelectron spectroscopy ; Fourier transform infrared spectroscopy ; Absorbance ; Anatase ; Citric acid ; Valence (chemistry) ; Analytical Chemistry (journal) ; Absorption spectroscopy ; Chemical engineering ; Nuclear chemistry ; Nanotechnology ; Chemistry ; Photocatalysis ; Organic chemistry ; Optics ; Catalysis Copper-based nanomaterials and applications ; ZnO doping and properties ; Electronic and Structural Properties of Oxides
Authors: Manju Lakshmi Seelam | Srinivasa Rao Yarraguntla | Venkata Kamala Kumari Paravastu | Sai Sirisha Vurukuti | Sai Sri Vastav Mylavarapu
Source: GSC Biological and Pharmaceutical Sciences (article, 2022-07-10)
Field: Materials Science — Biomaterials

Polymeric nanoparticles with stimuli-responsive properties for drug delivery In the last few decades, polymeric nanoparticles have been emerged as a most promising and viable technology for targeted and controlled delivery of drugs as well as delivery of bioactive compounds such as genes, drugs, nucleic acids and proteins among other things, in biomedical and pharmaceutical applications. They not only improve the solubility, bioavailability, and circulation time of previous medications, but they can also be tailor made to selectively release the drug at the target site. Furthermore, these polymeric nanoparticles can be transformed into stimuli sensitive systems based on either exogenous stimuli (such as ultrasound, light, electric pulses, magnetism) or by endogenous stimuli (such as PH, redox, enzymes, temperature, hypoxia, glucose) for efficient targeting and biodistribution of genes and drugs at specific sites. Polymeric nanoparticles for delivery of drugs and bioimaging has attained a considerable interest in various cancer therapies. In the present content, we discuss various types of stimuli-responsive-nanocarriers and their applications in different fields like bioimaging, drug delivery.,etc. Nanocarriers ; Drug delivery ; Nanotechnology ; Bioavailability ; Nanoparticle ; Biodistribution ; Drug ; Gene delivery ; Nanomedicine ; Chemistry ; Targeted drug delivery ; Pharmacology ; Materials science ; Biochemistry ; Medicine ; Genetic enhancement ; Gene ; In vitro Nanoparticle-Based Drug Delivery ; Nanoplatforms for cancer theranostics ; Ultrasound and Hyperthermia Applications
Authors: Nadia O. Laschuk | Iraklii I. Ebralidze | Olena V. Zenkina
Source: Canadian Journal of Chemistry (article, 2022-12-22)
Field: Materials Science — Polymers and Plastics

Polypyridine-based architectures for smart electrochromic and energy storage materials The emerging role of metal–organic coordination compounds in the development of electrochromic materials (ECMs) fueled a growing interest in both the development of the new systems and their effective integration into functional devices. Coordination complexes of late transition metals with polypyridine ligands, like 2′-bipyridine (bpy) and 2,2′:6′,2″-terpyridine (tpy) often feature bright colours as a result of strong metal-to-ligand charge transfer. These colours could be reversibly bleached by oxidation of the metal centre and restored upon the metal centre reduction. The colour and its intensity can be controlled in different ways: by changing the nature of the metal centre(s) and by structural modification of ligand(s); by the construction of various metal–organic motifs and embedding them into devices, as well as by controlled layer-by-layer growth of the coordination assemblies on the surface of interest. The versatility of the available molecular building blocks allows for the systematic programming of the desired properties of the metal–organic units that could be effectively translated into the devices. This makes polypyridine metal complexes advantageous candidates for the design of effective ECMs. Here, we review the evolution of ECMs and devices based on molecularly defined bpy and tpy coordination adducts of late transition metals integrated into functional electrochromic devices over the past decade. Electrochromism ; Chemistry ; Terpyridine ; Ligand (biochemistry) ; Transition metal ; Metal ; Combinatorial chemistry ; Nanotechnology ; Electrochromic devices ; Coordination complex ; Materials science ; Electrode ; Organic chemistry ; Catalysis ; Physical chemistry Conducting polymers and applications ; Transition Metal Oxide Nanomaterials ; Polyoxometalates: Synthesis and Applications
Authors: Céline Calviño
Source: CHIMIA International Journal for Chemistry (article, 2022-10-26)
Field: Chemistry — Organic Chemistry

Photocycloadditions for the Design of Reversible Photopolymerizations The quest for circular designs and ways to reuse polymer materials demands further advances in the development of reversible chemistries. Stimuli-responsive systems incorporated into polymer materials that enable the formation and cleavage of covalent bonds, hold great potential to reversibly decompose materials into their original building blocks. [2π+2π] photocycloadditions, for which the addition and reversion mechanism can be triggered by disparate wavelengths, stand as an attractive platform for triggering such controlled and reversible photoligation towards achieving renewable polymer materials. This perspective highlights the potential of this type of photochemistry to incorporate solid polymer materials and generate reversible polymerizations. The design of effective photoresponsive materials with specific functions requires the consideration of a number of parameters. Following a bottom-up approach - from molecular chemistry to macromolecular functionality - this perspective provides a recipe of the key aspects to consider in the design of such advanced renewable materials. Furthermore, examples of the state of the art in the field are highlighted and an overview of the fundamental challenges that remain is provided. Finally, an outlook on the next frontiers to cross is proposed. Polymer ; Nanotechnology ; Design elements and principles ; Material Design ; Materials science ; Computer science Advanced Polymer Synthesis and Characterization ; Synthetic Organic Chemistry Methods ; Photopolymerization techniques and applications