jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Yubin M. Kwon
Source: Western CEDAR (Western Washington University) (article, 2020-05-20)
Field: Chemistry — Organic Chemistry

Synthesis & Reactivity of Iron (II) Pyridinediimine Complexes For the Reduction of Nitrite The activation of small molecules has been studied by the scientific field for many decades as it plays a key role in nature such as photosynthesis and respiration. Many of these reactions are catalyzed by metalloenzymes in nature where the transfer of electrons and protons are coupled for the reaction to move forward. Noncovalent interactions in the secondary coordination sphere of metalloenzymes play an important role in determining the activity and selectivity. Hydrogen bonds are the most common noncovalent interactions that metalloenzymes utilize to control the reactivity in the secondary coordination sphere. Therefore, it is important to develop compounds and catalysts that can move both protons and electrons. Recent studies have been done by several groups on the mechanism of nitrite reduction. Based on those findings, we developed a series of iron (II) pyridinediimine (PDI) complexes that contain pendant bases, with varying pKa values, located in the secondary coordination sphere. These ligands were synthesized, coordinated to iron (II) and reduced under carbon monoxide (CO) to store electrons within the ligand scaffold. These reduced complexes were then protonated to form hydrogen bonds and fine tune the reactivity. These PDI complexes that are capable of storing both electrons and protons were investigated to functionally mimic the metalloenzyme nitrite reductase. To date, the mechanism of nitrite reduction remains unknown. In an attempt to determine how nitrite binds to the metal of our PDI complex, we synthesized a dinitrosyl iron complex. The synthesis of this complex should help to determine the mechanism of nitrite reduction. Nitrite ; Chemistry ; Reactivity (psychology) ; Reduction (mathematics) ; Nitrate ; Organic chemistry ; Mathematics ; Medicine Nanomaterials for catalytic reactions ; Chemical Synthesis and Reactions ; Ammonia Synthesis and Nitrogen Reduction
Authors: Bong Lee | Anton V. Naumov | Conor Ryan | Thomas Paz | Fabian Grote
Source: ECS Meeting Abstracts (article, 2020-05-01)
Field: Materials Science — Materials Chemistry

Electric Field Quenching of Graphene Oxide Photoluminescence With the advent of graphene, there has been an interest in utilizing this material and its derivative, graphene oxide (GO) for novel applications in biotechnology, electronics, photonics, materials and environmental science. Although GO exhibits lower conductivity and structural stability, it possesses an energy band gap that enables fluorescence emission in the visible/near infrared leading to a plethora of optoelectronic applications. In order to enable fine-tuning of its optical properties in the device geometry, new physical techniques are required that unlike existing chemical approaches yielding substantial alteration of GO structure, enable electronically-controlled and, ideally, reversible changes in GO optoelectronic properties. In this work, we for the first time investigate the methods to controllably alter the optical response of GO with the electric field and provide theoretical modelling of the electric field-induced changes. Field-dependent GO emission is studied in bulk GO/PVP films with up to 6% reversible decrease under 1.6 V/µm electric fields. On an individual flake level a more substantial 50% quenching is achieved for select GO flakes in polymeric matrix between interdigitated microelectrodes subject to two orders of magnitude higher fields. This effect is modelled on a single exciton level by utilizing WKB approximation for electron escape form the exciton potential well. In an aqueous suspension at low fields GO flakes exhibit electrophoretic migration indicating a degree of charge separation and a possibility of manipulating GO materials on a single-flake level to assemble electric field-controlled microelectronics. As a result of this work, we suggest the potential of varying the optical and electronic properties of GO via the electric field for the advancement and control over its optoelectronic device applications. Graphene ; Electric field ; Materials science ; Exciton ; Quenching (fluorescence) ; Optoelectronics ; Band gap ; Photoluminescence ; Oxide ; Nanotechnology ; Photonics ; Charge carrier ; Chemical physics ; Fluorescence ; Condensed matter physics ; Optics ; Chemistry ; Physics Graphene research and applications ; Graphene and Nanomaterials Applications ; Molecular Junctions and Nanostructures
Authors: Jasmine M. Hershewe | William D. Wiseman | James E. Kath | Chelsea C. Buck | Maneesh K. Gupta | Patrick B. Dennis | Rajesh R. Naik | Michael C. Jewett
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2020-08-11)
Field: Materials Science — Biomaterials

Characterizing and controlling nanoscale self-assembly of suckerin-12 Abstract Structural proteins such as the “suckerins” present promising avenues for fabricating functional materials. Suckerins are a family of naturally occurring block copolymer-type proteins that comprise the sucker ring teeth of cephalopods and are known to self-assemble into supramolecular networks of nanoconfined β -sheets. Here, we report characterization and controllable, nanoscale self-assembly of suckerin-12 (S12). We characterize impacts of salt, pH, and protein concentration on S12 solubility, secondary structure, and self-assembly. In doing so, we identify conditions for fabricating ~100 nm nanoassemblies (NAs) with narrow size distributions. Finally, by installing a non-canonical amino acid (ncAA) into S12, we demonstrate the assembly of NAs that are covalently conjugated with a hydrophobic fluorophore, and the ability to change self-assembly and β -sheet content by PEGylation. This work presents new insights into the biochemistry of suckerin-12 and demonstrates how ncAAs can be used to expedite and fine-tune the design of protein materials. Nanotechnology ; Self-assembly ; Fluorophore ; Nanoscopic scale ; Copolymer ; Covalent bond ; Supramolecular chemistry ; Materials science ; Template ; PEGylation ; Chemistry ; Polymer ; Fluorescence ; Molecule ; Organic chemistry ; Polyethylene glycol Silk-based biomaterials and applications ; RNA Interference and Gene Delivery ; Supramolecular Self-Assembly in Materials
Authors: Aditya K. Sahu | Satyabrata Raj
Source: AIP conference proceedings (article, 2020-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Tuning of longitudinal surface plasmon resonance peak of gold nanorods for sensor applications Gold nanorods show interesting optical and electronic properties due to their morphology and are used in different types of sensing applications. For the sensing applications, the dimension of nanorods is very critical and thus the synthesis requires full control over its dimensions. Here we report a novel way to tune the longitudinal surface plasmon resonance peak by fine-tuning the dimensions of gold nanorods. This is achieved by the addition of the gold solution into the final nanorod solution. The color and optical properties of gold nanoparticles originate from the localized surface plasmons and the control of the rod dimensions depend on the double interaction between salt–gold and salt–surfactant (cetyl trimethyl ammonium bromide, CTAB). The different aspect ratio of gold nanorods leads to a huge blue shift from 790 to 557 nm of the longitudinal absorption peak. We propose a particle growth mechanism to change the shape of nanorods to a sphere, which has established applications in various demands, especially in sensing. Nanorod ; Surface plasmon resonance ; Materials science ; Plasmon ; Nanotechnology ; Surface plasmon ; Colloidal gold ; Resonance (particle physics) ; Absorption (acoustics) ; Localized surface plasmon ; Nanoparticle ; Ammonium bromide ; Optoelectronics ; Optics ; Pulmonary surfactant ; Chemical engineering ; Composite material Gold and Silver Nanoparticles Synthesis and Applications ; Plasmonic and Surface Plasmon Research ; Nanocluster Synthesis and Applications
Authors: Sooyoun Yu | Qi Chen | Steve Yang | Wilfred Chen | Nosang V. Myung
Source: ECS Meeting Abstracts (article, 2020-11-23)
Field: Materials Science — Biomaterials

Electrospun Nanofibers for Applications in Energy Harvesting and Generation Nanofibers have long been exploited as a versatile, attractive material compared to their bulk counterparts due to their exceptionally high specific surface area and aspect ratio, highly porous structure, and wide range of materials that can be used for synthesis. Such unique properties helped exhibit their potential in a variety of applications in areas of energy, healthcare, and environment. Applications in energy are widely studied especially because of the global need for a source of energy and method of energy production that is alternative to the combustion of fossil fuels, as it presents many environmental drawbacks, which ultimately lead to adverse health effects on humans. To bypass the use of fossil fuels, renewable sources such as wind, hydro, geothermal, and solar energy have been introduced; devices that take advantage of alternative sources of energy such as nanogenerators, fuel cells, and thermoelectric generators have been developed. In this work, hybrid nanofibers were fabricated with precise control of the working parameters to fine tune their properties for various applications, including piezoelectrics and enzymatic fuel cell electrodes. Pure polyacrylonitrile (PAN) nanofibers were first electrospun based on a series of design of experiments to minimize both the diameter and beading. By correlating the solution, electrospinning, and environmental conditions to the resulting solution and nanofiber properties, it was found that not only physical properties such as electrical conductivity but also electrochemical properties of the nanofibers could be controlled. Physical and electrochemical properties of porous carbonaceous nanofibers derived from PAN, zinc acetate and multi-walled carbon nanotubes were studied with SEM, 4-point probe measurement, CV, LSV, and EIS. Based on the electroanalytical methods, the best nanofiber mats were chosen and used as electrodes to immobilize multienzyme cascade systems, a concept of which was demonstrated with a glucose oxidase-BglA bienzymatic system on a customized DNA scaffold as the anodic biocatalyst. Nanofiber ; Materials science ; Electrospinning ; Polyacrylonitrile ; Carbon nanofiber ; Renewable energy ; Nanotechnology ; Fossil fuel ; Energy transformation ; Carbon nanotube ; Polymer ; Composite material ; Waste management Electrospun Nanofibers in Biomedical Applications ; Fuel Cells and Related Materials ; Microbial Fuel Cells and Bioremediation
Authors: Subhankar Kundu | A. Kasem Chowdhury | Somen Nandi | Kankan Bhattacharyya | Abhijit Patra
Source: ChemRxiv (preprint, 2020-12-08)
Field: Materials Science — Biomaterials

Deciphering Molecular Self-Assembly through Electron Microscopy and Fluorescence Correlation Spectroscopy Supramolecular self-assembly of small organic molecules has emerged as a powerful tool to construct well-defined micro- and nanoarchitecture through fine-tuning a range of intermolecular interactions. The size, shape, and optical properties of these nanostructures largely depend on the temperature and polarity of the medium, along with the specific self-assembled pattern of molecular building units. The engineering of supramolecular self-assembled nanostructures with morphology-dependent tunable emission is in high demand due to the promising scope in nanodevices and molecular machines. However, challenges are probing the evolution of molecular aggregates from a true solution and directing the self-assembly process in a pre-defined fashion. The structure of molecular aggregates in the solution can be predicted from fluorescence correlation spectroscopy (FCS) and dynamic light scattering (DLS) analysis. On the other hand, the morphology of the aggregates can also be visualized through electron microscopy. Nevertheless, a direct correlation between emission from molecular aggregates in the aqueous dispersion and their morphology obtained through a solid-state characterization is missing. In the present study, we decipher the sequential evolution of molecular nanofibers from solution to spherical and oblong-shaped nanoparticles through the variation of solvent polarity, adjusting the hydrophobic-hydrophilic interactions. The intriguing case of molecular self-assembly is elucidated employing a newly designed π-conjugated thiophene derivative (TPAn) through a combination of steady-state absorption, emission measurements, FCS, and electron microscopy. The FCS analysis and microscopy results infer that small-sized nanofibers in the dispersion are further agglomerated, resulting in a network of nanofibers upon solvent evaporation. The evolution of organic nanofibers and subtle control over the self-assembly process demonstrated in the current investigation provides a general paradigm to correlate the size, shape, and emission properties of diverse fluorescent molecular aggregates in complex heterogeneous media, including a human cell. Fluorescence correlation spectroscopy ; Dynamic light scattering ; Materials science ; Self-assembly ; Supramolecular chemistry ; Spectroscopy ; Nanofiber ; Nanotechnology ; Fluorescence spectroscopy ; Chemical physics ; Fluorescence ; Nanoparticle ; Molecule ; Chemistry ; Organic chemistry ; Optics Supramolecular Self-Assembly in Materials ; Luminescence and Fluorescent Materials ; Porphyrin and Phthalocyanine Chemistry
Authors: Francis D. Mayer | Pooya Hosseini-Benhangi | Edouard Asselin | Előd Gyenge
Source: ECS Meeting Abstracts (article, 2020-05-01)
Field: Chemistry — Electrochemistry

Scanning Electrochemical Microscopy (SECM) for High-Throughput Screening of Tin Oxide Derived Catalyst Arrays for CO<sub>2</sub> Electro-Reduction to Formate Formate produced from the electro-reduction of CO 2 has been proposed as a safe liquid alternative to hydrogen gas in renewable energy storage schemes 1 . However, catalysts for electro-reduction of CO 2 to formate reaction still suffer from poor stability and activity 2,3 . Furthermore, the CO 2 electroreduction catalysis discovery and screening process is generally hampered by slow, one catalyst sample at a time, experimental procedures. Our overall objective is to develop SECM as a reliable high-throughput technique for screening of electrocatalyst arrays. Here, using SECM, we evaluated the activity of three different tin oxide derived catalysts arranged in an array. Tin(IV) dioxide, has been previously shown to be one of the most promising catalysts for formate generation, while also being thermodynamically reduced to metallic tin at the potential at which CO2RR happens in an aqueous medium 4,5 . We created two different tin oxide derived catalysts by subjecting mirror-polished native tin oxide to electro-reduction at a constant potentials prior to the CO 2 reduction experiments. Electro-reduction of the native tin oxide surface at -3.00 V vs. Ag/AgCl yielded a tin(IV) dioxide deficient surface covered in nanospheres (≈70 um) while electro-reduction at -1.25 V vs. Ag/AgCl create a slightly porous surface exhibiting high proportion of tin(IV) dioxide. Fine tuning the SECM technique to analyze three samples (the two electroreduced and one native tin oxide surface) in an array, we demonstrate the successful evaluation of the electrocatalytic activities of these catalysts and we discuss the advantages and challenges of using SECM to screen catalysts for CO 2 reduction. 1. S. Fukuzumi, Joule , 1 , 689–738 (2017) https://doi.org/10.1016/j.joule.2017.07.007. 2. C. E. Moore and E. L. Gyenge, ChemSusChem , 10 , 3512–3519 (2017) http://doi.wiley.com/10.1002/cssc.201700761. 3. B. Khezri, A. C. Fisher, and M. Pumera, J. Mater. Chem. A , 5 , 8230–8246 (2017) http://xlink.rsc.org/?DOI=C6TA09875D. 4. A. Dutta, A. Kuzume, M. Rahaman, S. Vesztergom, and P. Broekmann, ACS Catal. , 5 , 7498–7502 (2015). 5. S. Geiger, O. Kasian, A. M. Mingers, K. J. J. Mayrhofer, and S. Cherevko, Sci. Rep. (2017). Figure 1 Tin ; Tin oxide ; Catalysis ; Electrocatalyst ; Formate ; Scanning electrochemical microscopy ; Materials science ; Oxide ; Electrochemistry ; Inorganic chemistry ; Tin dioxide ; Chemical engineering ; Chemistry ; Nanotechnology ; Electrode ; Metallurgy ; Organic chemistry ; Physical chemistry Electrochemical Analysis and Applications ; CO2 Reduction Techniques and Catalysts ; Electrocatalysts for Energy Conversion
Authors: Sujing Wang | Liyu Chen | Mohammad Wahiduzzaman | Antoine Tissot | Lin Zhou | Ilich A. Ibarra | Aída Gutiérrez‐Alejandre | Ji Sun Lee | Jong‐San Chang | Zheng Liu | Jérôme Marrot | William Shepard | Guillaume Maurin | Qiang Xu | Christian Serre
Source: ChemRxiv (preprint, 2020-07-16)
Field: Chemistry — Inorganic Chemistry

A Mesoporous Zirconium-Isophthalate Multifunctional Platform &lt;p&gt;Mesoporous materials suffer from limitations including poor crystallinity and hydrolytic stability, lack of chemical diversity, insufficient pore accessibility, complex synthesis and toxicity issues. Here the association of non-toxic Zr-oxo clusters and feedstock isophthalic acid (IPA) via a Homometallic-Multicluster-Dot strategy results in a robust crystalline mesoporous MOF, denoted as MIP-206, that overcomes the aforementioned limitations. MIP-206, built up from an unprecedented combination of Zr&lt;sub&gt;6&lt;/sub&gt; and Zr&lt;sub&gt;12&lt;/sub&gt; oxo-cluster inorganic building units into a single structure, exhibits accessible meso-channels of ca. 2.6 nm and displays excellent chemical stability under different hydrolytic and harsh conditions. Owing to the abundant variety of functionalized IPA linkers, the chemical environment of MIP-206 can be easily tuned without hampering pore accessibility due to its large pore windows. As a result, MIP-206 loaded with palladium nanoparticles acts as an efficient and durable catalyst for the dehydrogenation of formic acid under mild conditions, outperforming benchmark mesoporous materials. This paves the way towards the utilization of MIP-206 as a robust mesoporous platform for a wide range of potential applications.&lt;/p&gt; Mesoporous material ; Materials science ; Dehydrogenation ; Formic acid ; Hydrolysis ; Zirconium ; Nanotechnology ; Nanoparticle ; Chemical stability ; Chemical engineering ; Catalysis ; Chemistry ; Organic chemistry Metal-Organic Frameworks: Synthesis and Applications ; Polyoxometalates: Synthesis and Applications ; Chemical Synthesis and Reactions
Authors: Rasha A. Baseer | Ahmed Abdrabou | Eman S. Zarie | Rasha A.M Azouz | Heba M. Abo‐Salem
Source: Egyptian Journal of Chemistry (article, 2020-08-12)
Field: Chemistry — Organic Chemistry

Synthesis and Bioactivity Evaluation of Indole-Thiophene polymer with Molecular Docking Studies Emulsion polymerization of 2-amino-4-(1-benzyl-1H-indol-3-yl) thiophene-3-carbonitrile (ABITC) using ammonium persulfate (APS) as an oxidizing agent afforded two isomers of poly (2-amino-4-(1-benzyl-1H-indol-3-yl) thiophene-3-carbonitrile) (PABITC) with high molecular weight 35673 and 28596 g/mol. Chemical structure and morphology of the newly synthesized polymers were investigated by IR, 1HNMR, SEM, and GPC. Nano capsulation of ABITC, PABITC, and PABITC/Doxorubicin by polyethylene glycol (PEG) was achieved by the nano-precipitation method. The anti-proliferative activity of the newly synthesized PABITC and nano-capsulation against HepG2, Huh7, and A549 cancer cell lines were investigated using MTT assay. The result obtained indicates that the encapsulation of ABITC inside PEG-NP led to an improvement in their anti-proliferative activity against cancer cell lines compared to free ABITC. The free PABITC revealed moderate anti-proliferative activity against tested cells and their encapsulation form with PEG-NP revealed no significant change in the activity with the fold changed not exceed 1-time fold. Furthermore, the anti-proliferative activity of PABITC -NP was improved after Doxorubicin (DOX) encapsulation against tested cells compared to PABITC - PEG-NP. In addition, PABITC exhibited potent antibacterial activity against tested microbes comparing to monomer ABITC and the reference drug amikacin. Moreover, the binding mode of the monomer ABITC beside two repeated units of monomer inside the active site of the DNA gyrase B chain (PDB ID: 1KIJ) as promising bacterial target and CDK2 enzyme (PDB ID: 1PYE)] as promising cancer target was studied using molecular docking technique. Ammonium persulfate ; Chemistry ; MTT assay ; Monomer ; Docking (animal) ; Polyethylene glycol ; Thiophene ; Antibacterial activity ; Polymerization ; Stereochemistry ; Nuclear chemistry ; Combinatorial chemistry ; Polymer ; Biochemistry ; Cell growth ; Organic chemistry ; Bacteria ; Biology Synthesis and biological activity ; Synthesis and Characterization of Heterocyclic Compounds ; Synthesis and Biological Evaluation
Authors: Camila Utsunomia
Source: Open Access Journal of Microbiology & Biotechnology (article, 2020-01-01)
Field: Materials Science — Biomaterials

Applications and Perspectives of Biobased Oligomeric Esters in the Industry Our society has the imperative need to reduce the production, utilization, and pollution caused by petroleum-based materials. In addition to the biopolymers, such as polylactide (PLA) and polyhydroxyalkanoates (PHA), biobased oligoesters having a different set of properties and applications are yet to be explored as alternatives to materials derived from finite carbon sources. This mini-review highlights the potential applications of biobased oligoesters synthesized via chemical, enzymatic, and biological routes. Polyhydroxyalkanoates ; Biochemical engineering ; Polymer science ; Environmental pollution ; Carbon fibers ; Chemistry ; Organic chemistry ; Materials science ; Environmental science ; Engineering ; Biology ; Environmental protection ; Composite material biodegradable polymer synthesis and properties ; Carbon dioxide utilization in catalysis ; Catalysis for Biomass Conversion
Authors: Jingyu Liu | R. J. Linhardt | Paul L. DeAngelis
Source: UNC Libraries (article, 2020-11-03)
Field: Chemistry — Organic Chemistry

Chemoenzymatic synthesis of glycosaminoglycans: Re-creating, re-modeling and re-designing nature's longest or most complex carbohydrate chains Glycosaminoglycans (GAGs) are complex polysaccharides composed of hexosamine-containing disaccharide repeating units. The three most studied classes of GAGs, heparin/heparan sulfate, hyaluronan and chondroitin/dermatan sulfate, are essential macromolecules. GAGs isolated from animal and microbial sources have been utilized therapeutically, but naturally occurring GAGs are extremely heterogeneous limiting further development of these agents. These molecules pose difficult targets to construct by classical organic syntheses due to the long chain lengths and complex patterns of modification by sulfation and epimerization. Chemoenzymatic synthesis, a process that employs exquisite enzyme catalysts and various defined precursors (e.g. uridine 5′-diphosphosphate-sugar donors, sulfate donors, acceptors and oxazoline precursors), promises to deliver homogeneous GAGs. This review covers both theoretical and practical issues of GAG oligosaccharide and polysaccharide preparation as single molecular entities and in library formats. Even at this early stage of technology development, nearly monodisperse GAGs can be made with either natural or artificial structures. Glycosaminoglycan ; Carbohydrate ; Chemistry ; Stereochemistry ; Combinatorial chemistry ; Computer science ; Biochemistry Carbohydrate Chemistry and Synthesis ; Glycosylation and Glycoproteins Research ; Proteoglycans and glycosaminoglycans research