jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Khrystyna Herasymchuk
Source:  (preprint, 2021-05-24)
Field: Chemistry — Inorganic Chemistry

Low symmetry Pincer Ligands designed for applications in coordination chemistry and catalysis Pincer ligands are monoanionic, tridentate binding molecules that have been used in coordination chemistry as efficient homogeneous and heterogeneous catalysts (i.e. as transition metal complexes). The focus of this work lies in the synthesis, characterization and coordination chemistry of a series of novel asymmetric potentially monoanionic NN'N", NN'C and NN'P type pincer ligands with amide functionality derived from the skeleton of 2-(2'-anilinyl)-4,4-dimethyl-2-oxazoline. Modular approach to this synthesis has been developed through an alkyl halide intermediate, in addition to the substrate-dependent alternative pincer syntheses, which are also described. The coordination chemistries of Pd and Ni, as well as the potential application of these pincer complexes in metal mediated catalysis of aldehyde allylation reactions will be explored. Moreover, a number of Pd(II) pincer complexes have been successfully synthesized and structurally characterized and these results are likewise described. Pincer movement ; Chemistry ; Coordination complex ; Catalysis ; Amide ; Combinatorial chemistry ; Transition metal ; Oxazoline ; Homogeneous catalysis ; Stereochemistry ; Metal ; Organic chemistry Asymmetric Hydrogenation and Catalysis ; Chemical Synthesis and Analysis ; Organometallic Complex Synthesis and Catalysis
Authors: Mikail Aslan
Source: DÜMF Mühendislik Dergisi (article, 2021-03-29)
Field: Materials Science — Materials Chemistry

ErB6 ve Ce katkılı ErB6 Yapılarının Optiksel, Elektronik, Mekanik ve TermalÖzellikleri: Hesaplamalı MalzemeÇalışması Erbiyum hexaboride is one of the heavy rare aearth hexaborides that indicate superior chemical and physical properties. In this study, Erbiyum hexaboride and Ce doped Erbium hexaboride crystal structures have been investigated systematically employing ab initio material modeling. The effects of Ce doping (wt.%10) on Erbiyum hexaboride structure in terms of optical, thermal, mechanical and electronic properties including band properties, enthalpy of formation energies and bulk modules were investigated. Results show that the Ce doping leads to an increase in the bandgap of the structure. Furthermore, the bulk modules calculations show that Ce doping to the structure leads to an increase in mechanical properties. Materials science ; Doping ; Band gap ; Enthalpy ; Crystal structure ; Electronic band structure ; Electronic structure ; Crystallography ; Condensed matter physics ; Chemistry ; Thermodynamics ; Optoelectronics ; Physics Boron and Carbon Nanomaterials Research ; Superconductivity in MgB2 and Alloys ; Rare-earth and actinide compounds
Authors: Г. В. Семенова | A. Yu. Zavrazhnov
Source: Конденсированные среды и межфазные границы (review, 2021-08-17)
Field: Materials Science — Materials Chemistry

The development of methods for the research and synthesis of solid phases by the scientific school of Ya. A Ugai. Review The scientific school founded by Yakov A. Ugai has existed at Voronezh State University for over fifty years. One of its focus areas has been the development of physics and chemistry for obtaining solid phases in systems with volatile components. This determined the necessity to develop methods for the investigation of vapour pressure (tensimetric methods). This article only focuses on some of the works by the VSU staff dedicated to the study and construction of P-T-x diagrams. This review analyses phase equilibria and the nature of the intermediate phases in the AIV – BV, AIV – BV – СV, and AIII – BVI systems.Owing to the special nature of the cation-cation and anion-anion bonds, these compounds have highly specific properties that make them promising materials (2D materials in particular). The article presents an overview of works devoted to the construction of P-T-x diagrams and the investigation of defect formation processes in binary and ternary systems based on AIVBV compounds. It should be emphasised that the known techniques needed updating due to the high values of vapour pressure. This allowed conducting experiments at pressures of about 35-40 atmospheres. The study of the AIII - BVI systems,on the contrary, is complicated by low values of vapour pressure over indium and gallium chalcogenides and the complex composition of the vapour. For such systems the auxiliary component method was developed. The possibilities of its application are wide and are not limited to AIIIBVI compounds. A new method for nonstoichiometry regulation was developed and applied using non-destructive selective chemical transport reactions (i.e. with the participation of an auxiliary component). This method is based on the introduction or removal of one of the sample components by means of a selective chemical transport reaction. In conclusion, the development of methods for the research and synthesis of intermediate phases with variable compositions (properties) was analysed based on the example of the discussed systems. Vapor pressure ; Ternary operation ; Component (thermodynamics) ; Indium ; Phase diagram ; Thermodynamics ; Materials science ; Chemistry ; Computer science ; Physics ; Phase (matter) ; Metallurgy ; Organic chemistry Solid-state spectroscopy and crystallography
Authors: Jian‐Fei Bai | Jianbo Tang | Xiaolong Gao | Zhi‐Jiang Jiang | Zhanghua Gao
Source: ChemRxiv (preprint, 2021-12-31)
Field: Chemistry — Organic Chemistry

Transition Metal Catalyst Free Cross-Coupling Reaction of Tertiary Propargylic Alcohols with Hetero-Areneboronic Acids We report a perfluorophenylboronic acid catalyzed cross coupling reaction of tertiary propargylic alcohols and hetero-areneboronic acids for valuable benzo[b]thiophene and cyclopenta[a]indene derivates. This coupling reaction proceeds efficiently with a wide array of substrates scope in up to 89% yield and excellent regioselectivity. A significant advantage of our protocol is the transition metal catalyst free and mild conditions needed. This strategy provides direct and facile access to medicinally important benzo[b]thiophene and cyclopenta[a]indene scaffold containing a quaternary carbon center. Indene ; Catalysis ; Regioselectivity ; Chemistry ; Transition metal ; Yield (engineering) ; Thiophene ; Quaternary carbon ; Coupling reaction ; Combinatorial chemistry ; Tertiary alcohols ; Organic chemistry ; Materials science ; Enantioselective synthesis Catalytic Alkyne Reactions ; Catalytic Cross-Coupling Reactions ; Synthetic Organic Chemistry Methods
Authors: Jeffrey M. Lucas
Source: Scholarworks (University of Massachusetts Amherst) (article, 2021-04-01)
Field: Chemistry — Physical and Theoretical Chemistry

FLEXIBLE TETHERS IN MULTI-CHROMOPHORIC SYSTEMS: LINKING PHOTOPHYSICS WITH ASSEMBLY Consistent with the need for implementation research and prevention programming for students in schools, the current study evaluated the implementation and outcomes of <em>Strong Start</em>, a social-emotional learning program, as a supplemental intervention for students in kindergarten through second grade at risk for developing emotional and behavioral problems. This intervention took place during the first year of a county-wide restructuring of mental health supports and was part of a multi-tiered system of supports provided in schools. A mixed method program evaluation was conducted to examine four areas of interest. First, the contextual factors related to program adoption were examined; second, program implementation was evaluated; third, student outcomes were assessed; and finally, the social validity of the <em>Strong Start</em> curriculum was evaluated. Results indicate that some contextual factors were related to decisions to adopt and implement <em>Strong Start</em>, that implementation integrity varied but was adequate overall, and that the curriculum was viewed positively by multiple stakeholders. However, no significant differences were detected between treatment and comparison groups in this first year of program implementation. These results are discussed in reference to theoretical implementation models and used to elucidate the process and challenges encountered in the first year implementation of large-scale initiatives across multiple schools. Limitations of this study and directions for future research are discussed. Computer science Photochemistry and Electron Transfer Studies ; Porphyrin and Phthalocyanine Chemistry ; Photochromic and Fluorescence Chemistry
Authors: Nitin G. Valsange | Maria Nelly García González | Niklas Warlin | Smita V. Mankar | Nicola Rehnberg | Stefan Lundmark | Baozhong Zhang | Patric Jannasch
Source: Lund University Publications (Lund University) (article, 2021-01-01)
Field: Materials Science — Polymers and Plastics

Preparation and investigation of biobased aliphatic polyesters based on a rigid spirocyclic dicarboxylate derived from levulinic acid Levulinic acid ; Polyester ; Organic chemistry ; Chemistry ; Catalysis Polymer Synthesis and Characterization ; biodegradable polymer synthesis and properties
Authors: Zvart Ajoyan | Gabrielle A. Mandl | P. Rafael Donnarumma | Victor Quezada‐Novoa | Hudson A. Bicalho | Hatem M. Titi | John A. Capobianco | Ashlee J. Howarth
Source: ChemRxiv (preprint, 2021-11-29)
Field: Chemistry — Inorganic Chemistry

Modulating Photo- and Radioluminescence in Tb(III) Cluster-Based Metal–Organic Frameworks Luminescent metal–organic frameworks (MOFs) are of interest for sensing, theranostics, dosimetry, and other applications. The use of lanthanoids in MOF metal nodes allows for intrinsic met-al-based luminescence. In this work, a facile route for modulat-ing the photoluminescent and radioluminescent properties of Tb(III)-based MOFs is reported. By using Tb(III)-cluster nodes as X-ray attenuators, and organic linkers with varying excited state energies as sensitizers, MOFs with metal-based, linker-based, and metal+linker-based photo- and radioluminescence are reported. Radioluminescence ; Metal-organic framework ; Lanthanide ; Linker ; Luminescence ; Materials science ; Photoluminescence ; Excited state ; Cluster (spacecraft) ; Metal ; Terbium ; Nanotechnology ; Photochemistry ; Optoelectronics ; Chemistry ; Physical chemistry ; Scintillator ; Organic chemistry ; Computer science ; Optics ; Atomic physics ; Physics Metal-Organic Frameworks: Synthesis and Applications ; Lanthanide and Transition Metal Complexes ; Nanocluster Synthesis and Applications
Authors: Jian‐Fei Bai | Jianbo Tang | Xiaolong Gao | Zhi‐Jiang Jiang | Zhanghua Gao
Source: ChemRxiv (preprint, 2021-12-31)
Field: Chemistry — Organic Chemistry

Transition Metal Catalyst Free Cross-Coupling Reaction of Tertiary Propargylic Alcohols with Hetero-Areneboronic Acids We report a perfluorophenylboronic acid catalyzed cross coupling reaction of tertiary propargylic alcohols and hetero-areneboronic acids for valuable benzo[b]thiophene and cyclopenta[a]indene derivates. This coupling reaction proceeds efficiently with a wide array of substrates scope in up to 89% yield and excellent regioselectivity. A significant advantage of our protocol is the transition metal catalyst free and mild conditions needed. This strategy provides direct and facile access to medicinally important benzo[b]thiophene and cyclopenta[a]indene scaffold containing a quaternary carbon center. Indene ; Regioselectivity ; Catalysis ; Chemistry ; Transition metal ; Thiophene ; Yield (engineering) ; Quaternary carbon ; Coupling reaction ; Combinatorial chemistry ; Tertiary alcohols ; Organic chemistry ; Materials science ; Enantioselective synthesis Catalytic Alkyne Reactions ; Catalytic Cross-Coupling Reactions ; Synthetic Organic Chemistry Methods
Authors: Taeho Kang | Nana Kim | Peter T. W. Cheng | Hao Zhang | Klement Foo | Keary M. Engle
Source: ChemRxiv (preprint, 2021-03-16)
Field: Chemistry — Organic Chemistry

Nickel-Catalyzed 1,2-Carboamination of Alkenyl Alcohols An alcohol-directed, nickel-catalyzed three-component umpolung carboamination of unactivated alkenes with aryl/alkenylboronic esters and electrophilic aminating reagents is reported. This transformation is enabled by specifically tailored O-(2,6-dimethoxybenzoyl)hydroxylamine electrophiles that suppress competitive processes, including undesired β-hydride elimination and transesterification between the alcohol substrate and electrophile. The reaction delivers the desired 1,2-carboaminated products with excellent regio- and diastereoselectivity and exhibits a broad scope of coupling partners and alkenes, including complex natural products. Various mechanistic experiments and analysis of the stereochemical outcome with a cyclic alkene substrate, as confirmed by X-ray crystallographic analysis, support alcohol-directed syn-insertion of an organonickel(I) species. Umpolung ; Electrophile ; Alkene ; Chemistry ; Aryl ; Alcohol ; Catalysis ; Reagent ; Substrate (aquarium) ; Nickel ; Allylic rearrangement ; Transesterification ; Organic chemistry ; Combinatorial chemistry ; Medicinal chemistry ; Alkyl ; Nucleophile ; Biology Catalytic C–H Functionalization Methods ; Chemical Synthesis and Reactions ; Oxidative Organic Chemistry Reactions
Authors: Qing Yu | R. England | Anders Gunnarsson | Robert Luxenhofer | Kevin Treacher | Marianne Ashford
Source: ChemRxiv (preprint, 2021-12-16)
Field: Materials Science — Polymers and Plastics

Designing Highly Stable Poly(sarcosine)-based Telodendrimer Micelles with High Drug Content Exemplified with Fulvestrant Polymeric micelles have been extensively used as nanocarriers for the delivery of chemotherapeutic agents aiming to improve their efficacy in cancer treatment. However, poor loading capacity, premature drug release, non-uniformity and reproducibility still remain the major challenges. To create a stable polymeric micelle with high drug loading, a telodendrimer micelle was developed as a nanocarrier for fulvestrant, as an example of a drug that has extremely poor water solubility (sub nanomolar range). Telodendrimers were prepared by synthesis of a hydrophilic linear poly(sarcosine) and growing a lysine dendron from the chain terminal amine by a divergent synthesis. At the periphery of the dendritic block, 4, 8, and 16 fulvestrant molecules were conjugated to the lysine dendron creating a hydrophobic block. Having drug as part of the carrier not only reduces the usage of the inert carrier materials but also prevent the drugs from leakage and premature release by diffusion. The self-assembled telodendrimer micelles demonstrated good colloidal stability (CMC < 2 µM) in buffer and were uniform in size. In addition, these telodendrimer micelles could solubilize additional fulvestrant yielding an excellent overall drug loading capacity of up to 77 wt.% total drug load (summation of conjugated and encapsulated). Importantly, the size of the micelles could be tuned between 25-150 nm by controlling (i) the ratio between hydrophilic and hydrophobic blocks and (ii) the amount of encapsulated fulvestrant. The versatility of these telodendrimer-based micelle systems to both conjugate and encapsulate drug with high efficiency and stability, in addition to possessing other tuneable properties makes it a promising drug delivery system for a range of active pharmaceutical ingredients and therapeutic targets. Micelle ; Nanocarriers ; Fulvestrant ; Solubility ; Materials science ; Drug delivery ; Chemical engineering ; Sarcosine ; Chemistry ; Combinatorial chemistry ; Drug ; Organic chemistry ; Nanotechnology ; Aqueous solution ; Pharmacology ; Cancer Dendrimers and Hyperbranched Polymers ; Microplastics and Plastic Pollution ; Ferrocene Chemistry and Applications
Authors: Sarah N. Dishman | Croix J. Laconsay | James C. Fettinger | Dean J. Tantillo | Jared T. Shaw
Source: ChemRxiv (preprint, 2021-07-02)
Field: Chemistry — Organic Chemistry

Divergent Stereochemical Outcomes in the Insertion of Donor/Donor Carbenes into the C–H Bonds of Stereogenic Centers Intramolecular C–H insertions with donor/donor dirhodium carbenes provide a concise and highly stereoselective method to set two contiguous stereocenters in a single step. Herein, we report the insertion of donor/donor carbenes into stereogenic carbon centers allowing access to trisubstituted benzodihydrofurans in a single step. This study illuminates, for the first time, the stereochemical impact on the carbene center and delineates the structural factors that enable control over both stereogenic centers. Sterically bulky, highly activated C–H insertion centers exhibit high substrate control yielding a single diastereomer and a single enantiomer of product regardless of the catalyst used. Less bulky, less activated C–H insertion centers exhibit catalyst control over the diastereomeric ratio (dr) wherein a single enantiomer of each diastereomer is observed. A combination of experimental studies and DFT calculations elucidates the origin of these results. First, hydride transfer from the stereogenic insertion site proceeds with high stereoselectivity to the carbene center, thus determining the absolute configuration of the product. Second, the short lived zwitterionic intermediate can undergo diastereoselective ring-closure by an SE2 mechanism that is either controlled by the substrate or the catalyst. These results demonstrate that donor/donor carbenes exhibit uniquely stereoselective reactions that originate from a stepwise reaction mechanism, in contrast to the analogous concerted reactions of carbenes with one or more electron-withdrawing groups attached. Stereocenter ; Diastereomer ; Chemistry ; Carbene ; Stereoselectivity ; Intramolecular force ; Stereochemistry ; Steric effects ; Insertion reaction ; Catalysis ; Enantioselective synthesis ; Organic chemistry Cyclopropane Reaction Mechanisms ; Catalytic C–H Functionalization Methods ; Asymmetric Hydrogenation and Catalysis
Authors: Nihal Kanbargi
Source: Scholarworks (University of Massachusetts Amherst) (article, 2021-04-01)
Field: Materials Science — General Materials Science

ENGINEERING NEXT GENERATION ANISOTROPIC MATERIALS AND COMPOSITES Equal segregation of the genome is a prerequisite for cell survival. During cell division the duplicated DNA is compacted into chromosomes and a multi-protein macrostructure, known as the kinetochore (Kt), is assembled on each copy of compacted DNA. Simultaneously, the mitotic spindle, which is made up of microtubules (MTs), is built to facilitate the equal distribution of the chromosomes between the resulting daughter cells. Kinetochores mediate the interaction between the MTs and the chromosomes, properly positioning them for segregation. To ensure that the DNA is equally divided in every cell division, cells have built a surveillance system to detect any errors that may occur. An important checkpoint during mitosis is the spindle assembly checkpoint (SAC), which ensures that all chromosomes are forming the appropriate attachments with MTs. In cases of erroneous attachment, mitotic progression is halted and an error correction pathway is activated to give chromosomes a second change to establish proper attachment. When all the chromosomes have achieved biorientation, cells progress into anaphase, where each copy of the DNA is pulled toward opposite axis of the cell. It is critical that chromosome are properly attached and aligned to ensure equal segregation, as misegragation is the leading cause of cell death or cancer. Finally, a cleavage furrow is formed at the cell equator that constricts and severs the cell, giving rise to two daughters. It is remarkable how cells are able to go through many rounds of division without any errors. Although a lot of work has been done to further understand the mechanisms in which cells detect and correct potential catastrophic error, many more mystery remains to be uncovered. In the last six years, I tried to make my contribution to field by exploring how a previously classified as a non-motile kinesin generates force to move chromosomes, how much force is being exerted on a bioriented kinetochore, the roles aurora kinases play to ensure proper kinetochore-microtubule attachment and proper cytokinesis. Composite material ; Materials science ; Anisotropy ; Physics ; Optics Material Properties and Applications
Authors: Paulo Henrique Michels-Brito | Leander Michels | Kristoffer W. Bø Hunvik | Éverton Carvalho dos Santos | Barbara Pacáková | Leide P. Cavalcanti | Kenneth D. Knudsen | Heloisa N. Bordallo | O. Fossum
Source: OAJ Materials and Devices (article, 2021-01-14)
Field: Materials Science — Biomaterials

Experimental methods to study clay minerals and perspective applications of Fluorohectorite Fluorohectorite is a synthetic 2:1 layer smectite clay where the presence of exchangeable cations located between water molecules in the interlayer space allows for expansion of the crystal lattice. This swelling property is extremely relevant to many applications including water treatment, bioactive molecules intercalation (drug delivery), soil remediation, CO2capture as well as extra-terrestrial environment studies. In the present chapter, the aim is to discuss why Fluorohectorite can be in particular advantageous for many applications where retention of big volumes is an issue. We will also discuss on the main experimental techniques used to study these materials. Clay minerals ; Intercalation (chemistry) ; Environmental remediation ; Swelling ; Materials science ; Chemical engineering ; Mineralogy ; Nanotechnology ; Chemistry ; Geology ; Inorganic chemistry ; Contamination ; Composite material ; Engineering Clay minerals and soil interactions ; Soil and Unsaturated Flow ; Layered Double Hydroxides Synthesis and Applications
Authors: Linda Zedler | Pascal Wintergerst | Alexander K. Mengele | Carolin Müller | Chunyu Li | Benjamin Dietzek‐Ivanšić | Sven Rau
Source: ChemRxiv (preprint, 2021-11-22)
Field: Chemistry — Organic Chemistry

Which bridge to cross, which mountain to climb – Supramolecular Photocatalysis Outpacing Conventional Catalysis Unequivocal assignment of rate limiting steps in supramolecular photocatalysts is of utmost importance to rationally optimize photocatalytic activity. By spectroscopic and catalytic analysis of a series of three structurally similar [(tbbpy) 2 Ru-BL-Rh(Cp*)Cl] 3+ photocatalysts just differing in the central part (alkynyl, triazole or phenazine) of the bridging ligand (BL) we were able to derive design strategies for improved photocatalytic activity of this class of compounds (tbbpy = 4,4´-tert-butyl- 2,2´-bipyridine, Cp* = pentamethylcyclopentadienyl). Most importantly, not the rate of the transfer of the first electron towards the Rh III center but rather the rate at which a two-fold reduced Rh I species is generated can directly be correlated with the observed photocatalytic formation of NADH from NAD + . Interestingly, the complex which exhibited the fastest intramolecular electron transfer kinetics for the first electron is not the one that allowed the fastest photocatalysis. With the photocatalytically most efficient alkynyl linked system, it was even possible to overcome the rate of thermal NADH formation. Moreover, for this photocatalyst loss of the alkynyl functionality under photocatalytic conditions was identified as an important deactivation pathway. Photocatalysis ; Catalysis ; Chemistry ; Photochemistry ; Electron transfer ; Intramolecular force ; Bridging ligand ; Supramolecular chemistry ; Combinatorial chemistry ; Stereochemistry ; Molecule ; Organic chemistry Catalytic C–H Functionalization Methods ; Nanocluster Synthesis and Applications ; CO2 Reduction Techniques and Catalysts