jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Catherine D. Pugh
Source: Wellesley College Digital RepositoryWellesley (Wellesley College) (article, 2019-01-01)
Field: Chemistry — Organic Chemistry

Acylated Sulfa Drugs: A Phthesis on the Synthesis of Acylated Sulfa Compounds in Connection with Antitubercular Drug Design Tuberculosis (TB) is an infectious disease caused by the organism Mycobacterium tuberculosis (MTB). Improved sanitation and successful chemotherapy have largely eliminated TB in industrialized countries, but it remains a serious threat to lower socio-economic classes, the immunocompromised population, and developing countries where industrialization is just taking hold. Although two new drugs have surfaced in the last decade, they are largely reserved for compassionate cases because of the severity of their side effects. The first-line TB treatment prescribed by the World Health Organization and the Center for Disease Control and Prevention remains the comparatively small number of drugs synthesized or isolated in the 1950’s and 1960’s. These drugs, while currently effective, can cause adverse side effects such as liver toxicity. Additionally, the emergence of strains of drug-resistant TB threatens to completely undermine existing treatment regimens and enable TB to reach a level of prevalence not experienced for the past century.\nIn the past decade, studies have suggested intriguing antitubercular possibilities offered by applying modern methods to a very early class of drugs: the sulfa drugs. Sulfa drugs work by mimicking the natural molecule para-aminobenzoic acid, inhibiting dihydropteroate synthase (DHPS) and resulting in cell death. Arylamine N-acetyltransferases (NATs) de-activate sulfa drugs inside the body by catalyzing the transfer of an acetyl group onto position N4 of the sulfa molecule. NATs also appear in M. tuberculosis, where they act as a defense mechanism for MTB against chemotherapy.\nMy work in the Hearn lab has been guided by recent crystallographic images of the DHPS binding pocket and the deactivating mechanism of NATs, as well as by previous studies in our lab that demonstrated that acylation can improve activity and bioavailability while reducing toxicity. Our work began with the development of a reliable protocol to prepare the acetylated NAT metabolites. We then explored a number of different procedures for increasing acyl chain length at N4, focusing on derivatives of sulfamethazine; and then continued to selective di-acylation at both N4 and N1, varying both chain length and steric bulk for a number of different sulfa drug scaffolds. Several of our acylated sulfa derivatives possess improved biological and anti-tubercular properties over their parent drugs. Moreover, the compounds serve as probes of the structural factors influencing biological activity such as fit within DHPS, resistance to the de-activating effects of NATs, and permeability. Drug ; Connection (principal bundle) ; Pharmacology ; Medicine ; Engineering Synthesis and biological activity ; Phenothiazines and Benzothiazines Synthesis and Activities ; Quinazolinone synthesis and applications
Authors: Zhenyu Yang
Source: theses.fr (ABES) (preprint, 2019-12-17)
Field: Materials Science — Materials Chemistry

Synthesis and characterization of Yb/Er co-doped different cubic fluoride-based NIR to VIS up-conversion nanoparticles L'objectif de ce projet de doctorat est de développer la synthèse de nanoparticules de fluoré dopées avec des ions de terres rares ou de métaux de transition pour de nouvelles applications en nanophotonique, telles que des sondes pour l'imagerie thermique à l'échelle nanométrique. Les nanoparticules peuvent également être utilisées pour le revêtement de cellules photovoltaïques afin d'optimiser leur rendement par absorption d'une large gamme de longueurs d'ondes. La particularité des particules fluorées dopées avec les ions adéquats consiste à présenter, par exemple, des processus efficaces de conversion ascendante ou des émissions infrarouges efficaces, en raison de la nature ionique élevée de la liaison métal-fluor. L'accent sera mis sur le développement et l'optimisation des procédés millifluidiques à basse température qui sont en mesure d'assurer la chimie, la morphologie et les homogénéités de taille des nanoparticules telles que celles obtenues. Les nanoparticules synthétisées seront caractérisées (composition chimique, distribution de taille, morphologie) ainsi que leurs propriétés physiques, en particulier les propriétés de la luminescence. La possibilité d'une migration des processus de synthèse millifluidique vers les processus microfluidiques devrait être explorée.. Doping ; Nanoparticle ; Characterization (materials science) ; Materials science ; Fluoride ; Chemical engineering ; Nanotechnology ; Nuclear chemistry ; Inorganic chemistry ; Chemistry ; Optoelectronics ; Engineering Luminescence Properties of Advanced Materials ; Inorganic Fluorides and Related Compounds ; Perovskite Materials and Applications
Authors: Christian R. Zwick | Max B. Sosa | Hans Renata
Source: ChemRxiv (preprint, 2019-08-20)
Field: Chemistry — Organic Chemistry

Concise Chemoenzymatic Total Synthesis of GE81112 B1 and Simplified Analogs Enable Elucidation of Its Key Pharmaco-phores We report a chemoenzymatic total synthesis of GE81112 B1 that employs biocatalytic hydroxylation to prepare two of the key monomers of the target natural product. By pairing this strategy with traditional organic chemistry, we were able to synthesize GE81112 B1 in 11 steps. Following this strategy, six GE81112 analogs were synthesized, allowing for elucidation of its key pharmacophores. Pharmacophore ; Total synthesis ; Natural product ; Hydroxylation ; Chemistry ; Key (lock) ; Combinatorial chemistry ; Stereochemistry ; Biochemical engineering ; Organic chemistry ; Computer science ; Enzyme ; Engineering Carbohydrate Chemistry and Synthesis ; Glycosylation and Glycoproteins Research ; Microbial Natural Products and Biosynthesis
Authors: Divya S. Nair | P S Dileep
Source: International Journal of Scientific Research in Science and Technology (article, 2019-11-01)
Field: Materials Science — Materials Chemistry

Development of Nickel Doped Zinc Ferrite Nanocomposites as Magnetically Recoverable Catalytic Material for The Synthesis of Biphenyl Methane Magnetically active nickel doped zinc ferrite nanoparticles with chemical composition NixZn1-xFe2O4 (x- 0.0, 0.25, 0.5, 0.75 and 1.0) were successfully synthesized by sol-gel auto-combustion method using high purity metal nitrates and ethylene glycol as gelling agent. The prepared samples were characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), X-ray Fluorescence (XRF) and Fourier Transform Infra-Red spectral (FTIR) analyses. TEM images and particle size distribution profile reveals the agglomeration tendency during nickel doping suggest the magnetic nature of particles. The remarkable change in the magnetic behaviour of nickel doped zinc ferrite samples provide an easy recovery and regeneration of the material and thus making an excellent candidate for benzylation reaction without any remarkable fall in the catalytic performance for repeated cycles. Zinc ferrite ; Materials science ; Zinc ; Ethylene glycol ; Nickel ; Nanocomposite ; Chemical engineering ; Fourier transform infrared spectroscopy ; Ferrite (magnet) ; Nanoparticle ; Transmission electron microscopy ; Doping ; Particle size ; Catalysis ; Nuclear chemistry ; Inorganic chemistry ; Metallurgy ; Nanotechnology ; Chemistry ; Organic chemistry ; Composite material Magnetic Properties and Synthesis of Ferrites ; Nanomaterials for catalytic reactions ; Advancements in Battery Materials
Authors: Lukas J. Jongkind
Source: UvA-DARE (University of Amsterdam) (article, 2019-01-01)
Field: Chemistry — Organic Chemistry

Ligand based encapsulation strategies in homogeneous catalysis The development of catalysts has enabled highly specialized processes that are of great value to mankind. A relatively new strategy for the development of new homogeneous catalysts involves the use of supramolecular capsules. The encapsulation of homogeneous catalysts in molecular capsules is of interest as activity, selectivity and stability can be controlled by the capsule, which acts as second coordination sphere, reminiscent of how enzymes control chemical reactivity. Homogeneous catalysts however, are not static guest molecules as catalysts change in shape, charge and polarity during the catalytic cycle, representing the challenges involved in capsule controlled catalysis. To address the problems associated with catalyst encapsulation, we developed the ‘ligand-template approach’, which focusses on using the properties of a ligand molecule to encapsulate homogeneous catalysts. We have used the ligand template approach to encapsulate rhodium hydroformylation catalysts in cages suitable for switchable catalysis and in chiral capsule, leading to asymmetric catalysis. In addition to the ligand-template approach we have developed the ‘ligand based encapsulation’ strategy, which is the general approach of using the properties of a ligand molecule to both bind to a transition metal atom and to a supramolecular capsule. In this thesis we use this approach to affect catalysis in rhodium catalyzed hydroformylation and ruthenium catalyzed ring-closing metathesis reactions. Hydroformylation ; Catalysis ; Rhodium ; Supramolecular chemistry ; Homogeneous catalysis ; Chemistry ; Supramolecular catalysis ; Ligand (biochemistry) ; Combinatorial chemistry ; Molecule ; Nanotechnology ; Materials science ; Organic chemistry Organometallic Complex Synthesis and Catalysis ; Asymmetric Hydrogenation and Catalysis ; Synthetic Organic Chemistry Methods
Authors: Nico König | Lutz Willner | Vitaliy Pipich | Thomas Zinn | Reidar Lund
Source: Physical Review Letters (article, 2019-02-21)
Field: Chemistry — Organic Chemistry

Cooperativity during Melting and Molecular Exchange in Micelles with Crystalline Cores Molecular exchange processes are important equilibration and transport mechanisms in both synthetic and biological self-assembled systems such as micelles, vesicles, and membranes. Still, these processes are not entirely understood, in particular the effect of crystallinity and the interplay between cooperative melting processes and chain exchange. Here we focus on a set of simple polymer micelles formed by binary mixtures of poly(ethylene oxide)-mono-n-alkyl-ethers (C_{n}-PEO5) which allows the melting point to be tuned over a wide range. We show that the melting transition is cooperative in the confined 4-5 nm micellar core, whereas the exchange process is widely decoupled and unimeric in nature. As confirmed by differential scanning calorimetry, the total activation energy for ejecting a molecule out of the micellar core below the melting point is the sum of the enthalpy of fusion and the corresponding activation energy in the melt state. This suggests that a "local, single-chain melting process" preludes the molecular diffusion out of the micelle during chain exchange. Micelle ; Cooperativity ; Chemistry ; Mineralogy ; Materials science ; Crystallography ; Geology ; Organic chemistry ; Aqueous solution ; Biochemistry Surfactants and Colloidal Systems ; Crystallization and Solubility Studies ; Chemical and Physical Properties in Aqueous Solutions
Authors: Philip Ferko
Source: IRL - University of Missouri, St. Louis (University of Missouri–St. Louis) (article, 2019-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Capabilities and Limitations of the Spin Hamiltonian Formalism in Single Molecule Magnets The rational design of molecular magnetic materials is an ongoing effort involving physics, materials science, and chemistry. A common approach to design of complexes and interpretation of magnetic data is the spin Hamiltonian formalism. In this approach, magnetic data is interpreted through constants extracted from the parameterization of data. In design, certain structural motifs are pursued, rationalized by the minimization or maximization of terms in the spin Hamiltonian. In this work, monometallic complexes were prepared to simplify magnetic behavior and allow the examination of specific factors that influence single molecule magnetism like coordination geometry, ligand identity, symmetry, and spin-orbit coupling. A series of hydridotris(3-phenylpyrazolylborato) scorpionate compounds are presented, some of which are inadequately described by the parameterization of magnetic data, and others for which the alteration of terms within the spin Hamiltonian gives the predicted result. These discoveries and ramifications for single molecule magnetism will be discussed. A series of dmf adducts of transition metal para-toluenesulfonates is also presented. Formalism (music) ; Magnet ; Physics ; Hamiltonian (control theory) ; Classical mechanics ; Theoretical physics ; Quantum mechanics ; Mathematics ; Mathematical optimization Magnetism in coordination complexes ; Quantum and electron transport phenomena ; Magnetic properties of thin films
Authors: M Olteanu | Raluca Şeptelean | Ovidiu Nemeș | Delia Grec | Emese Gál | Dan Porumb | György Deák | Andreea Baraitaru
Source: Materiale Plastice (article, 2019-09-30)
Field: Materials Science — Materials Chemistry

Functionalization of Mesoporous Silica Materials Using Calix[4]arenes \Six new products were obtained by deposition of para-tert-butylcalix[4]arene (t-Bu-C4OH), calix[4]arene (C4OH) and tetra-methoxy-calix[4]arene (C4OMe) on two types of SBA-15 mesoporous silica. All the products were characterized through thermogravimetric methods and SEM microscopy. The obtained results confirm the functionalization of the silica materials with the calixarene macrocycles. Considering all the obtained products, the thermal analysis suggests the strongest connectivity to form between the C4OMe systems and mesoporous silica substrate. Surface modification ; Thermogravimetric analysis ; Mesoporous silica ; Calixarene ; Mesoporous material ; Substrate (aquarium) ; MCM-41 ; Deposition (geology) ; Materials science ; Tetra ; Mesoporous organosilica ; Chemical engineering ; Chemistry ; Polymer chemistry ; Nanotechnology ; Organic chemistry ; Catalysis ; Molecule ; Medicinal chemistry ; Geology ; Sediment Mesoporous Materials and Catalysis ; Zeolite Catalysis and Synthesis ; Porphyrin and Phthalocyanine Chemistry
Authors: Ilenia Rossetti | Antonio Tripodi | E. Bahadori | Gianguido Ramis
Source: Archivio Istituzionale della Ricerca (Universita Degli Studi Di Milano) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Innovative high pressure photoreactors for the photoreduction of CO2 High pressure ; Business ; Environmental science ; Engineering ; Engineering physics Catalytic Processes in Materials Science ; Catalysts for Methane Reforming ; Atmospheric and Environmental Gas Dynamics
Authors: Shinya Moribe | Zhijie Chen | Selim Alayoǧlu | Zoha H. Syed | Timur İslamoğlu | Omar K. Farha
Source: ChemRxiv (preprint, 2019-08-05)
Field: Chemistry — Inorganic Chemistry

Ammonia Capture within Isoreticular Metal-Organic Frameworks with Rod Secondary Building Units The efficient removal, capture, and recycling of ammonia (NH&lt;sub&gt;3&lt;/sub&gt;) constitutes a demanding process, thus the development of competent adsorbent materials is highly desirable. The implementation of metal-organic frameworks (MOFs), known for their tunability and high porosity, has attracted much attention for NH&lt;sub&gt;3&lt;/sub&gt; adsorption studies. Here, we report three isoreticular porphyrin-based MOFs containing aluminum (&lt;b&gt;Al-PMOF&lt;/b&gt;), gallium (&lt;b&gt;Ga-PMOF&lt;/b&gt;), and indium (&lt;b&gt;In-PMOF&lt;/b&gt;) rod secondary building units with Brønsted acidic bridging hydroxyl groups. NH&lt;sub&gt;3&lt;/sub&gt; sorption isotherms in &lt;b&gt;Al-PMOF&lt;/b&gt; demonstrated reversibility in isotherms. In contrast, the slopes of the adsorption isotherms in &lt;b&gt;Ga-PMOF&lt;/b&gt; and &lt;b&gt;In-PMOF&lt;/b&gt; were much steeper than &lt;b&gt;Al-PMOF&lt;/b&gt; in lower pressure regions, with a decrease of NH&lt;sub&gt;3&lt;/sub&gt; adsorbed amounts observed between first cycle and second cycle measurements. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) suggested that the strength of the Brønsted acidic -OH sites was controlled by the identity of the metal, which resulted in stronger interactions between ammonia and the framework in &lt;b&gt;Ga-PMOF&lt;/b&gt; and &lt;b&gt;In-PMOF &lt;/b&gt;compared to&lt;b&gt; Al-PMOF&lt;/b&gt;. Chemistry ; Ammonia ; Adsorption ; Metal ; Calcination ; Sorption ; Nuclear chemistry ; Organic chemistry ; Catalysis Metal-Organic Frameworks: Synthesis and Applications ; Carbon Dioxide Capture Technologies ; Magnesium Oxide Properties and Applications
Authors: Mila Miletic | Karol Pałczynski | Matheus Jacobs | Ana M. Valencia | Caterina Cocchi | Joachim Dzubiella
Source: The Journal of Physical Chemistry C (preprint, 2019-02-21)
Field: Materials Science — Materials Chemistry

Impact of Polarity on Anisotropic Diffusion of Conjugated Organic Molecules on the (1010) Zinc Oxide Surface We study the influence of polarity on the binding and diffusion of single conjugated organic molecules on the inorganic (101̅0) zinc oxide surface by means of all-atom molecular dynamics simulations at room temperature and above. In particular, we consider the effects of partial fluorination of the para-sexiphenyl (p-6P) molecule with chemical modifications of one head group (p-6P2F) or both (symmetric) head and tail (p-6P4F). Quantum-mechanical and classical simulations both result in consistent and highly distinct dipole moments and densities of the fluorinated molecules, which interestingly lead to a weaker adhesion to the surface than for p-6P. The diffusion for all molecules is found to be normal and Arrhenius-like for long times. Intriguingly, close to room temperature, the polar molecules diffuse 1–2 orders of magnitude slower compared to the p-6P reference in the apolar x-direction of the electrostatically heterogeneous surface, whereas in the polar y-direction, they diffuse 1–2 orders of magnitude faster. We demonstrate that this rather unexpected behavior is governed by a subtle electrostatic anisotropic mismatch between the polar molecules and the chemically specific surface, as well as by increased entropic contributions coming from orientational and internal degrees of freedom. Molecule ; Polarity (international relations) ; Chemical physics ; Polar ; Dipole ; Diffusion ; Chemical polarity ; Anisotropy ; Chemistry ; Oxide ; Conjugated system ; Molecular dynamics ; Zinc ; Arrhenius equation ; Materials science ; Computational chemistry ; Physical chemistry ; Polymer ; Thermodynamics ; Organic chemistry ; Physics ; Optics ZnO doping and properties ; Advanced Chemical Physics Studies ; Spectroscopy and Quantum Chemical Studies
Authors: Rycel Uy
Source: Carolina Digital Repository (University of North Carolina at Chapel Hill) (article, 2019-08-15)
Field: Materials Science — Polymers and Plastics

Structure-Property Optimizations of Semiconducting Polymers for Organic Solar Cells Many advances in organic photovoltaic efficiency are not yet fully understood and new insight into structure-property relationships is required in order to push this technology into broad commercial use. The aim of this work is to utilize synthetic strategies to create new molecular designs for donor polymer systems used in organic solar cells. Of particular interest are the underexplored issues surrounding the popular donor polymers benzodithiophene-thienothiophene (PBnDT-TT) and benzodithiophene-fluorinated triazole (PBnDT-FTAZ) and determining how to take advantage of high dielectric constant materials. In response to structural and electronic limitations, this work will focus on: (1) improving the synthesis of the thienothiazole (TTz) moiety to tune the energy levels of PBnD-TT, (2) advantageously utilizing electron-withdrawing substituents to further functionalize TTz-based polymers, (3) designing a high dielectric constant polymer to enhance exciton splitting at the donor/acceptor interface, and (4) structure-property optimizations to increase open circuit voltage and decrease band gap in fluorinated triazole polymers. The unifying motivation behind each of these projects is establishing synthetic strategies to achieve creative molecular designs that will ultimately improve performance in organic solar cells. Polymer ; Property (philosophy) ; Organic solar cell ; Materials science ; Nanotechnology ; Polymer science ; Composite material ; Philosophy Conducting polymers and applications ; Organic Electronics and Photovoltaics
Authors: Angela Yang
Source: Carolina Digital Repository (University of North Carolina at Chapel Hill) (article, 2019-08-15)
Field: Materials Science — Biomaterials

Exploring and harnessing PEG-immune system interactions to engineer targeted stealth nanoparticles Effective nanoparticle drug delivery to tumor cells typically relies on prolonged systemic circulation of the nanoparticles to allow for extravasation and accumulation in tumor tissue, as well as targeting ligands on the nanoparticles that can mediate receptor-specific uptake by target tumor cells. Due to the ability of polyethylene glycol (PEG) to effectively reduce nonspecific protein binding and cell clearance, PEGylation has become a commonplace strategy for formulating long-circulating nanoparticle systems. However, the precise characteristics (e.g., PEG molecular weight and density) that influence the interactions between PEG-coated nanoparticles and phagocytic immune cells remain poorly understood for many nanoparticle systems, and findings from human studies suggest that the body is further able to mount PEG-specific humoral responses to PEG-coated agents. Additionally, the presence of targeting ligands on the nanoparticle surface may also compromise the extended circulation profile of PEG-coated nanoparticles. To address these challenges and gaps in our understanding, in this dissertation quantitative approaches and systematic analyses were utilized to 1) evaluate the interactions between phagocytic cells and various PEG coatings on polymeric nanoparticles, 2) determine the prevalence and concentrations of different anti-PEG antibody isotypes amongst the general human population, and 3) apply an alternative approach for PEGylated nanoparticle delivery to tumors. The results indicated that extremely dense PEG coatings (RF/D >> 2.8) are required to effectively minimize nonspecific clearance by immune cells. Using competitive ELISAs and engineered antibody standards, the anti-PEG IgG1-4 and IgM levels in a large number of healthy human samples were quantified, with the majority of samples possessing detectable anti-PEG IgG and/or IgM. Finally, a multistep targeting (i.e., pretargeting) approach was tested for the delivery of biotin PEG-modified nanoparticles to disparate tumor cells in vitro and in vivo. The analytical methodologies and overall findings described here can inform future studies of PEGylated nanoparticle-immune system interactions and nanoparticle targeting strategies. Nanotechnology ; Nanoparticle ; Engineering ; Computer science ; Materials science Nanoparticle-Based Drug Delivery ; Nanoplatforms for cancer theranostics ; Advanced Biosensing Techniques and Applications