jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Ilia Kevlishvili
Source: D-Scholarship@Pitt (University of Pittsburgh) (article, 2021-10-08)
Field: Chemistry — Organic Chemistry

Computational Studies of Transition Metal-Catalyzed Olefin Functionalization and Cross-Coupling Reactions Transition metal-catalyzed reactions have become one of the most critical tools for organic chemists. In particular, olefin functionalization and cross-coupling reactions provide access to a wide array of interesting compounds. Understanding reaction mechanisms play a crucial role in discovering new reactions and increasing the selectivity and scope of existing reactions. However, experimental methods are often insufficient to understand key mechanistic insights, and new reaction discovery often relies on trial-and-error. To address these challenges, I present a series of density functional theory (DFT) calculations to study the reaction mechanisms of various transition metal-catalyzed olefin functionalization and cross-coupling reactions. I applied a wide variety of computational methods, including energy decomposition analysis (EDA), distortion-interaction analysis, ligand steric contour plots, and conformational sampling, to understand complex factors that could promote reactivity or selectivity, such as ligand and substrate effects, conformational flexibility of ligands and substrates, and solvent and additive effects. Insights into the factors that promote reactivity are then used for a mechanistically guided catalyst design for improving reactivity. Specifically, these computational approaches were applied to study copper-catalyzed hydroamination of olefins, copper-catalyzed allylation of indazoles, palladium-catalyzed regio-divergent cross-coupling of 3,5-dibromo-pyrone, a series of cross-coupling reactions of carbohydrates, and tandem nickel/zinc-catalyzed boron insertion into alkyl ether bonds. Chemistry ; Reactivity (psychology) ; Combinatorial chemistry ; Steric effects ; Coupling reaction ; Catalysis ; Olefin fiber ; Computational chemistry ; Transition state ; Catalytic cycle ; Organic chemistry Catalytic C–H Functionalization Methods ; Electrocatalysts for Energy Conversion ; Asymmetric Hydrogenation and Catalysis
Authors: Aiting Kai | Benjamin D. Egleston | Rob Clowes | Michael E. Briggs | Andrew I. Cooper | Rebecca L. Greenaway
Source:  (preprint, 2021-06-22)
Field: Chemistry — Inorganic Chemistry

Modular Type III Porous Liquids based on Porous Organic Cage Microparticles The dispersion of particulate porous solids in size-excluded liquids has emerged as a method to create Type III porous liquids, mostly using insoluble microporous materials such as metal-organic frameworks (MOFs) and zeolites. Here, we present the first examples of Type III porous liquids based on porous organic cages (POCs). By exploiting the solution processability of the POCs, racemic and quasiracemic cage microparticles were formed by chiral recognition. Dispersion of these porous microparticles in a range of size-excluded liquids, including oils and ionic liquids, formed stable POC-based Type III porous liquids. The flexible pairing between the solid POC particles and a carrier liquid allows the formation of a range of compositions, pore sizes, and other physicochemical properties to suit different applications and operating conditions. Porosity ; Microporous material ; Porous medium ; Materials science ; Chemical engineering ; Ionic liquid ; Dispersion (optics) ; Cage ; Nanotechnology ; Organic chemistry ; Chemistry ; Composite material ; Catalysis Metal-Organic Frameworks: Synthesis and Applications ; Covalent Organic Framework Applications ; Supramolecular Chemistry and Complexes
Authors: Miriam M. Unterlass
Source: Materials Advances (article, 2021-01-01)
Field: Materials Science — Materials Chemistry

<i>Journal of Materials Chemistry A</i> and <i>Materials Advances</i> Editor's choice web collection: “Recent advances in hydrothermal materials synthesis” Miriam M. Unterlass introduces a <italic>Journal of Materials Chemistry</italic>/<italic>Materials Advances</italic> Editor's choice web collection on recent advances in hydrothermal materials synthesis (https://rsc.li/hydrothermal). Hydrothermal circulation ; Hydrothermal synthesis ; Nanotechnology ; Materials science ; Engineering ; Chemical engineering Catalytic Processes in Materials Science ; Mesoporous Materials and Catalysis ; Zeolite Catalysis and Synthesis
Authors: Xiumin Liu | Wenzhi Li | Yuxi Wang | Yaping Tao | Yi Wang | Yingmin Hou
Source: Research Square (preprint, 2021-05-27)
Field: Chemistry — Physical and Theoretical Chemistry

Theoretical Investigation of Excited-State Intramolecular Double-Proton Transfer Mechanism of Substituent Modified 1, 3-Bis (2-pyridylimino)-4,7-dihydroxyisoindole in Dichloromethane Solution Abstract Density functional theory (DFT) and time-dependent DFT (TDDFT) methods were used to investigate substituent effects and excited-state intramolecular double-proton transfer in 1, 3-bis (2-pyridylimino)-4, 7-dihydroxyisoindole (BPI-OH) and its derivatives. The results of a systematic study of the substituent effects of electron-withdrawing groups (F, Cl, and Br) on the adjacent sites of the benzene ring were used to regulate the photophysical properties of the molecules and the dynamics of the proton-transfer process. Geometric structure comparisons and infrared spectroscopic analysis confirmed that strengthening of the intramolecular hydrogen bond in the first excited state (S 1 ) facilitated proton transfer. Functional analysis of the reduction density gradient confirmed these conclusions. Double-proton transfer in BPI-OH is considered to occur in two steps, i.e., BPI-OH (N) →BPI-OH (T 1 ) →BPI-OH (T 2 ), in the ground state (S 0 ) and the S 1 state. The potential-energy curves for two-step proton transfer were scanned for both the S 0 and S 1 states to clarify the mechanisms and pathways of proton transfer. The stepwise path in which two protons are consecutively transferred has a low energy barrier and is more rational and favorable. This study shows that the presence or absence of coordinating groups, and the type of coordinating group, affect the hydrogen-bond strength. A coordinating group enhances hydrogen-bond formation, i.e., it promotes excited-state intramolecular proton transfer. Substituent ; Dichloromethane ; Intramolecular force ; Excited state ; Proton ; Chemistry ; Mechanism (biology) ; Photochemistry ; State (computer science) ; Computational chemistry ; Medicinal chemistry ; Stereochemistry ; Organic chemistry ; Physics ; Solvent ; Atomic physics ; Computer science ; Quantum mechanics Photochemistry and Electron Transfer Studies ; Porphyrin and Phthalocyanine Chemistry ; Chemical Reactions and Mechanisms
Authors: Tatsuhiko Yoshino | Shigeki Matsunaga
Source: Institutional Repositories DataBase (IRDB) (article, 2021-05-17)
Field: Chemistry — Organic Chemistry

Chiral Carboxylic Acid Assisted Enantioselective C-H Activation with Achiral (CpMIII)-M-x (M = Co, Rh, Ir) Catalysts Enantioselective C-H functionalization is a powerful tool for synthesizing chiral molecules. In the past few years, the combination of high-valent group 9 metals with achiral Cp-x ligands and chiral carboxylic acids (CCA) has emerged as a promising catalytic system to enable selective cleavage and functionalization of enantiotopic C-H bonds. This Perspective summarizes the background, catalyst design, and applied reactions in detail, followed by a discussion of future directions. Enantioselective synthesis ; Catalysis ; Surface modification ; Carboxylic acid ; Cleavage (geology) ; Chirality (physics) Catalytic C–H Functionalization Methods ; Cyclopropane Reaction Mechanisms ; Asymmetric Hydrogenation and Catalysis
Authors: Daniel Rozsar | Michele Formica | Ken Yamazaki | Trevor A. Hamlin | Darren J. Dixon
Source: ChemRxiv (preprint, 2021-04-02)
Field: Chemistry — Organic Chemistry

Bifunctional Iminophosphorane Catalyzed Enantioselective Sulfa-Michael Addition to Unactivated α,β-Unsaturated Amides &lt;div&gt;The first metal-free catalytic intermolecular enantioselective sulfa-Michael addition to unactivated &lt;i&gt;α&lt;/i&gt;,&lt;i&gt;β&lt;/i&gt;- unsaturated amides is described. Consistently high enantiomeric excesses, and yields were obtained over a wide range of alkyl thiol pronucleophiles and electrophiles under mild reaction conditions, enabled by a novel squaramide-based bifunctional iminophosphorane (BIMP) catalyst. Low catalyst loadings (2 mol%) were achieved on a decagram scale, demonstrating the scalability of the reaction. Computational analysis revealed the origin of the high enantiofacial selectivity, corresponding transition states, and provided substantial evidence for specific non-covalent activation of the carbonyl group of the &lt;i&gt;α&lt;/i&gt;,&lt;i&gt;β&lt;/i&gt;-unsaturated amide by the catalyst.&lt;/div&gt; Bifunctional ; Enantioselective synthesis ; Chemistry ; Catalysis ; Electrophile ; Addition reaction ; Amide ; Michael reaction ; Alkyl ; Squaramide ; Medicinal chemistry ; Organocatalysis ; Organic chemistry Synthetic Organic Chemistry Methods ; Organic and Inorganic Chemical Reactions ; Asymmetric Hydrogenation and Catalysis
Authors: Beata Łukasik | Justyna Kowalska | Sebastian Frankowski | Łukasz Albrecht
Source: ChemRxiv (preprint, 2021-03-31)
Field: Chemistry — Inorganic Chemistry

Vinylogous Hydrazone Strategy for the Organocatalytic Alkylation of Heteroaromatic Derivatives A new umpolung approach for the asymmetric FriedelCrafts-type alkylation of electron-poor heteroaromatic systems has been developed. It is based on the vinylogous reactivity of hydrazones derived from heteroaromatic aldehydes. Donating effect of the hydrazone moiety can be efficiently transferred over the heteroaromatic system activating it towards asymmetric FriedelCrafts reaction with α,β-unsaturated aldehydes realized under aminocatalytic conditions. Excellent enantioselectivities have been obtained owing to the application of MacMillan imidazolidinone catalyst. Unmasking of hydrazone moiety has been also realized resulting in the development of a unique strategy for the asymmetric functionalization of electron-poor heteroaromatic systems. Umpolung ; Hydrazone ; Moiety ; Alkylation ; Chemistry ; Catalysis ; Organic chemistry ; Combinatorial chemistry ; Nucleophile Asymmetric Hydrogenation and Catalysis ; Asymmetric Synthesis and Catalysis ; Synthetic Organic Chemistry Methods
Authors: Jonathan Berry | Thisbe K. Lindhorst | Guillaume Despras
Source:  (preprint, 2021-10-29)
Field: Materials Science — Materials Chemistry

Sulfur and azobenzenes, a profitable liaison: straightforward synthesis of photoswitchable thioglycosides with tunable properties Azobenzene photoswitches are valuable tools for controlling properties of molecular systems with light. In particular, we have been investigating azobenzene glycoconjugates to probe carbohydrate-protein interactions and also to design photoresponsive glycomacrocycles with modulable chiroptical and physicochemical properties. To date, direct conjugation of glycosides to azobenzenes was performed by reactions providing target compounds in limited yields. We therefore sought for a more effective and reliable coupling method. In this paper, we report on a straightforward thioarylation of azobenzene derivatives with glycosyl thiols as well as other thiol substrates, increasing the scope of azobenzene conjugation. Importantly, red-shifted azoswitches that can be addressed with visible light were easily functionalized and challenging unsymmetrical conjugates were prepared in good yields via sequential or one pot procedures. In addition, we took advantage of the presence of the sulfide bridge to tune both photochromic and thermal relaxation properties of the core azobenzene via sulfur oxidation. Based on our photochemical investigations, we finally demonstrated orthogonal three-state photoswitching in mixtures containing two distinct azobenzene thioglycosides. Azobenzene ; Photochromism ; Chemistry ; Combinatorial chemistry ; Photochemistry ; Photoswitch ; Organic chemistry ; Molecule Photochromic and Fluorescence Chemistry ; Click Chemistry and Applications ; Carbohydrate Chemistry and Synthesis
Authors: Jonathan Berry | Thisbe K. Lindhorst | Guillaume Despras
Source:  (preprint, 2021-10-27)
Field: Materials Science — Materials Chemistry

Sulfur and azobenzenes, a profitable liaison: straightforward synthesis of photoswitchable thioglycosides with tunable properties Azobenzene photoswitches are valuable tools for controlling properties of molecular systems with light. In particular, we have been investigating azobenzene glycoconjugates to probe carbohydrate-protein interactions and also to design photoresponsive glycomacrocycles with modulable chiroptical and physicochemical properties. To date, direct conjugation of glycosides to azobenzenes was performed by reactions providing target compounds in limited yields. We therefore sought for a more effective and reliable coupling method. In this paper, we report on a straightforward thioarylation of azobenzene derivatives with glycosyl thiols as well as other thiol substrates, increasing the scope of azobenzene conjugation. Importantly, red-shifted azoswitches that can be addressed with visible light were easily functionalized and challenging unsymmetrical conjugates were prepared in good yields via sequential or one pot procedures. In addition, we took advantage of the presence of the sulfide bridge to tune both photochromic and thermal relaxation properties of the core azobenzene via sulfur oxidation. Based on our photochemical investigations, we finally demonstrated orthogonal three-state photoswitching in mixtures containing two distinct azobenzene thioglycosides. Azobenzene ; Photochromism ; Chemistry ; Combinatorial chemistry ; Photochemistry ; Photoswitch ; Molecule ; Organic chemistry Photochromic and Fluorescence Chemistry ; Click Chemistry and Applications ; Carbohydrate Chemistry and Synthesis
Authors: Milena Timcenko | Anton A. A. Autzen | Henriette Elisabeth Autzen
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2021-10-07)
Field: Chemistry — Spectroscopy

Characterization of divalent cation interactions with AASTY native nanodiscs Abstract Amphiphilic copolymers show promise in extracting membrane proteins directly from lipid bilayers into ‘native nanodiscs’. However, many such copolymers are polyanionic and sensitive to divalent cations, limiting their applicability. We characterize the Ca 2+ and Mg 2+ sensitivity of poly(acrylic acid-co-styrene) (AASTY) copolymers with analytical UV and fluorescent size exclusion chromatography, enabling us to separate signals from nanodiscs, copolymers, and soluble aggregates. We find that divalent cations promote aggregation and precipitation of both free and lipid bound copolymers. We see that excess, free copolymer acts as a ‘cation sink’ that protects nanodiscs from Ca 2+ induced aggregation. Removal of the free copolymer through dialysis induces aggregation that can be mitigated by KCl. Finally, we find that the nanodisc size is dynamic and dependent on lipid concentration. Our results offer insight to nanodisc behaviour, and can help guide experimental design, aimed at mitigating the shortcomings inherent in negatively charged nanodisc forming copolymers. Nanodisc ; Copolymer ; Divalent ; Chemistry ; Amphiphile ; Biophysics ; Lipophilicity ; Polymer chemistry ; Lipid bilayer ; Combinatorial chemistry ; Membrane ; Polymer ; Organic chemistry ; Biochemistry Molecular Sensors and Ion Detection ; Lipid Membrane Structure and Behavior ; Nanopore and Nanochannel Transport Studies
Authors: Merve Şenğül ALPATER | Zaid H. Al-Sawaff | Fatma Kandemi̇rlı
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2021-12-30)
Field: Materials Science — Materials Chemistry

Theoretical study of gallium nitride nanocage as a carrier for Cisplatin anticancer drug In this paper, the possible interactions between cisplatin Cl2H6N2Pt as an anticancer drug and gallium nitride (Ga12N12) nanocage have been investigated using the DFT/b3lyp/lanl2dz(d,p) level of theory. Three different orientations were used to mimic the cisplatin adsorbed on Ga12N12. To investigate the interaction mechanism between the two components, the adsorption energies and thermodynamic parameters, the electronic properties such as the energies and orbitals distribution of the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the HOMO-LUMO energy gaps (Eg), thermodynamic properties were also investigated. Additionally, some quantum molecular descriptors were calculated to understand molecular reactivity. The main results revealed that the adsorption process of the drug compound on the surface of the nanocage varies with the adsorption site. The process showed that different energies could be obtained, where the highest energy value was when the drug compound was adsorbed with the nanocage at the chlorine atom, with a value of (41.85) kcal/mol. On the other hand, the distance between the drug compound atoms was affected before and after adsorption, which proves the existence of an interaction between the drug compound and the nanocage and considers it as a drug delivery vehicle. Nanocages ; Cisplatin ; Gallium nitride ; Pharmacology ; Anticancer drug ; Drug ; Medicine ; Cancer research ; Materials science ; Chemistry ; Nanotechnology ; Internal medicine ; Chemotherapy ; Biochemistry Boron and Carbon Nanomaterials Research ; GaN-based semiconductor devices and materials ; Fullerene Chemistry and Applications
Authors: Serguei Fomine | Wilmer E. Vallejo Narváez | César Gabriel Vera de la Garza | Luis Daniel Solís Rodríguez
Source: Mundo Nano Revista Interdisciplinaria en Nanociencia y Nanotecnología (article, 2021-12-08)
Field: Materials Science — Materials Chemistry

Oligomeric approach to 2D materials modeling Oligomeric approach has been originally developed to study electronic properties of conjugated polymers. This approach allows to access electronic properties of 1D systems otherwise difficult to calculate. We successfully extended this method to study electronic properties of 2D materials. In this review we summarize our recent work in this area. It has been established that large graphene nanoflake possess multiconfigurational singlet or even high spin ground state. Doping of 2D systems has also been explored and it has been demonstrated that doping allows to tune their electronic properties, including ionization potentials, electron affinities, reorganization energies and the very nature of the ground state. The electronic properties of novel 2D allotropies of carbon, phosphorus, germanium and silicon have been studied as well as their complexes with Li. Heterostructures, of different 2D allotropies are readily formed. This is an alternative method for tuning of their electronic properties. Materials science ; Electronic structure ; Graphene ; Singlet state ; Silicon ; Doping ; Ground state ; Conjugated system ; Electron affinity (data page) ; Chemical physics ; Heterojunction ; Ionization ; Ionization energy ; Nanotechnology ; Computational chemistry ; Polymer ; Chemistry ; Optoelectronics ; Atomic physics ; Physics ; Molecule ; Organic chemistry Graphene research and applications ; 2D Materials and Applications ; MXene and MAX Phase Materials
Authors: Samuel Mensah | Kojo Asare
Source: Pharmaceutical Sciences and Drug Design (article, 2021-01-01)
Field: Chemistry — Organic Chemistry

Novel 1,2,3-Triazole-Urea Conjugates as Potent and Liver-Selective Antiproliferative Agents: Synthesis, Biological Evaluation, and Mechanistic Insights The need for effective targeted agents against hepatocellular carcinoma remains pressing. This investigation focused on designing and examining a new panel of triazole–urea hybrid molecules for potential anticancer activity. A collection of urea derivatives containing terminal alkynes was generated using a combined assembly and modification route. These intermediates were subsequently transformed through Click chemistry to afford novel triazole–urea hybrids (3a–3e, 5a–5e, 7a–7e). Their growth-in Conjugate ; Small molecule ; Click chemistry ; Cytotoxicity ; Biological activity ; Hepatocellular carcinoma ; Structure–activity relationship ; Urea Click Chemistry and Applications ; Cancer, Hypoxia, and Metabolism ; Peroxisome Proliferator-Activated Receptors
Authors: Nande Abena Wright
Source:  (preprint, 2021-05-23)
Field: Chemistry — Inorganic Chemistry

Synthesis and Application of Chiral Palladium-Phosphane Precatalyst in Enantioselective C-N Cross-Coupling The various strategies and reaction conditions towards the synthesis of benzene-, naphthalene-, and phenanthrene-based dicyclohexylbiaryl phosphanes are presented. A chiral third generation Buchwald-type precatalyst has been synthesized, employing the non-commercially available ligand, (R)-dicyclohexyl(2'-methoxy-[1,1'-binaphth-2-yl])phosphane, (R)-Cy2MOP, and a dimeric methanesulfonate-bridged palladacycle based on a 2-aminobiphenyl scaffold. Application of the palladacyclic precatalyst in an enantioselective variant of the BuchwaldHartwig reaction is demonstrated in the desymmetrization of prochiral α-(2-bromobenzyl)malonamides via intramolecular N-arylation. The scope of the catalysis in the presence of the precatalyst has been investigated with efforts towards optimizing yields, catalyst loading, and enantioselectivities. Attempts towards the isolation of a potential reaction intermediate in the form of a stable amido-bound palladium complex are discussed. Finally, strategies towards gaining mechanistic insight on the origin of the enantiomeric excess are discussed. Enantioselective synthesis ; Desymmetrization ; Chemistry ; Palladium ; Catalysis ; Ligand (biochemistry) ; Intramolecular force ; Combinatorial chemistry ; Naphthalene ; Allene ; Enantiomer ; Organic chemistry Asymmetric Hydrogenation and Catalysis ; Axial and Atropisomeric Chirality Synthesis ; Asymmetric Synthesis and Catalysis
Authors: Chayanit Wechwithayakhlung | Suttipong Wannapaiboon | Sutassana Na-Phattalung | Phisut Narabadeesuphakorn | Similan Tanjindaprateep | Saran Waiprasoet | Satoshi Horike | Pichaya Pattanasattayavong
Source: ChemRxiv (preprint, 2021-06-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Mixed-Metal Cu-Zn Thiocyanate Coordination Polymers with Melting Behavior, Glass Transition, and Tunable Electronic Properties &lt;p&gt;The solid-state mechanochemical reactions under ambient conditions of CuSCN and Zn(SCN)&lt;sub&gt;2&lt;/sub&gt; resulted in two novel materials: partially Zn-substituted &lt;i&gt;α&lt;/i&gt;-CuSCN and a new phase Cu&lt;sub&gt;x&lt;/sub&gt;Zn&lt;sub&gt;y&lt;/sub&gt;(SCN)&lt;sub&gt;x+2y&lt;/sub&gt;. The reactions take place at the labile S-terminal, and both products show melting and glass transition behaviors. The optical band gap and solid-state ionization potential can be adjusted systematically by adjusting the Cu:Zn ratio. Density functional theory calculations also reveal that the Zn-substituted CuSCN structure features a complementary electronic structure of Cu 3&lt;i&gt;d&lt;/i&gt; states at the valence band maximum (VBM) and Zn 4&lt;i&gt;s&lt;/i&gt; states at the conduction band minimum (CBM). This work shows a new route to develop semiconductors based on coordination polymers which are becoming technologically relevant for electronic and optoelectronic applications.&lt;/p&gt; Valence (chemistry) ; Band gap ; Transition metal ; Electronic structure ; Chemistry ; Density functional theory ; Crystallography ; Thiocyanate ; Conduction band ; Materials science ; Metal ; Phase (matter) ; Inorganic chemistry ; Computational chemistry ; Metallurgy ; Optoelectronics ; Electron ; Physics Organic and Molecular Conductors Research ; Metal-Organic Frameworks: Synthesis and Applications ; Conducting polymers and applications