jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Yisong Wang | Zepeng Zhang | Yan Xu
Source: Macromolecules (article, 2023-11-13)
Field: Chemistry — Organic Chemistry

<i>cis</i> -Selective Acyclic Diene Metathesis Polymerization Using Bulky Cyclometalated Ruthenium Carbene Catalysts The regulation of the cis–trans configuration is important for investigating the structure–property relationship and fine-tuning the properties of olefin-containing polymers. While classic metathesis polymerization typically yields trans-enriched polymer backbones, the selective construction of all-cis-configured polyalkenamers was previously restricted to the use of strained cyclic olefins or methyl/ethyl-capped acyclic cis-dienes as monomers. Here, we report an efficient and diverse-oriented cis-selective acyclic diene metathesis (ADMET) using readily available terminal acyclic dienes, which achieves a high cis-percentage of up to 99% and satisfactory molar mass by a bulky cyclometalated ruthenium–carbene catalyst. This method is further compatible with trans-olefin embedded triene monomers, providing a convenient tool for constructing alternative cis–trans configurations in polyalkenamers. A cis-ADMET-prepared and G2-degradable polymer was also explored. This work expands the possibilities for precision polymer synthesis and may offer new avenues for material design. Acyclic diene metathesis ; Carbene ; Metathesis ; Ruthenium ; Monomer ; Diene ; Chemistry ; Polymerization ; Catalysis ; Polymer ; Olefin metathesis ; Olefin fiber ; Polymer chemistry ; Combinatorial chemistry ; Organic chemistry Synthetic Organic Chemistry Methods ; biodegradable polymer synthesis and properties ; Organometallic Complex Synthesis and Catalysis
Authors: Antoine Combes | Corentin Rieb | Lucie Haye | Andrey S. Klymchenko | Christophe A. Serra | Andreas Reisch
Source: Langmuir (article, 2023-11-13)
Field: Materials Science — Biomaterials

Mixing versus Polymer Chemistry in the Synthesis of Loaded Polymer Nanoparticles through Nanoprecipitation Polymer nanoparticles (NPs) loaded with drugs and contrast agents have become key tools in the advancement of nanomedicine, requiring robust technologies for their synthesis. Nanoprecipitation is a particularly interesting technique for the assembly of loaded polymer NPs, which is well-known to proceed under kinetic control, with a strong influence of the assembly conditions. On the other hand, the nature of the used polymer also influences the outcome of nanoprecipitation. Here, we investigated systematically the relative effects of mixing of the organic and aqueous phases and polymer chemistry on the formation of polymer nanocarriers. For this, two mixing schemes, manual mixing and microfluidic mixing using an impact-jet micromixer, were first evaluated, showing mixing times of several tens of milliseconds and a few milliseconds, respectively. Copolymers of ethyl methacrylate with charged and hydrophilic groups and different polyesters (poly(d-l-lactide-<i>co</i>-glycolide) and poly(lactic acid)) were combined with a fluorescent dye salt and tested for particle assembly using these "slow" and "fast" mixing methods. Our results showed that in the case of the most hydrophobic polymers, the speed of mixing had no significant influence on the size and loading of the formed NPs. In contrast, in the case of less hydrophobic polymers, faster mixing led to smaller NPs with better encapsulation. The switch between mixing and polymer-controlled assembly was directly correlated to the solubility limit of the polymers in acetonitrile-water mixtures, with a critical point for solubility limits between 15 and 20 vol % of water. Our results provide simple guidelines on how to evaluate the possible influence of polymer chemistry and mixing on the formation of loaded NPs, opening the way to fine-tune their properties and optimize their large-scale production. Polymer ; Nanoparticle ; Mixing (physics) ; Chemistry ; Chemical engineering ; Nanotechnology ; Polymer science ; Organic chemistry ; Materials science Nanoparticle-Based Drug Delivery ; Advanced Polymer Synthesis and Characterization ; Nanomaterials for catalytic reactions
Authors: Fiora Artusio | José A. Gavira | Roberto Pisano
Source: Crystal Growth & Design (article, 2023-03-31)
Field: Materials Science — Materials Chemistry

Self-Assembled Monolayers As a Tool to Investigate the Effect of Surface Chemistry on Protein Nucleation Modified surfaces like siliconized glass are commonly used to support protein crystallization and facilitate obtaining crystals. Over the years, various surfaces have been proposed to decrease the energetic penalty required for consistent protein clustering, but scarce attention has been paid to the underlying mechanisms of interactions. Here, we propose self-assembled monolayers that are surfaces exposing fine-tuned moieties with a very regular topography and subnanometer roughness, as a tool to unveil the interaction between proteins and functionalized surfaces. We studied the crystallization of three model proteins having progressively narrower metastable zones, i.e., lysozyme, catalase, and proteinase K, on monolayers exposing thiol, methacrylate, and glycidyloxy groups. Thanks to comparable surface wettability, the induction or the inhibition of nucleation was readily attributed to the surface chemistry. For example, thiol groups strongly induced the nucleation of lysozyme thanks to electrostatic pairing, whereas methacrylate and glycidyloxy groups had an effect comparable to unfunctionalized glass. Overall, the action of surfaces led to differences in nucleation kinetics, crystal habit, and even crystal form. This approach can support the fundamental understanding of the interaction between protein macromolecules and specific chemical groups, which is crucial for many technological applications in the pharmaceutical and food industry. Nucleation ; Crystallization ; Protein crystallization ; Monolayer ; Chemistry ; Wetting ; Macromolecule ; Lysozyme ; Chemical engineering ; Crystallography ; Crystal (programming language) ; Thaumatin ; Methacrylate ; Chemical physics ; Nanotechnology ; Materials science ; Organic chemistry ; Polymer ; Polymerization Enzyme Structure and Function ; Protein purification and stability ; nanoparticles nucleation surface interactions
Authors: Jiadong Wang | Min Wang | Chenxin Xu | Yang Han | Xuan Qin | Liqun Zhang
Source: Polymers (article, 2023-06-09)
Field: Materials Science — Polymers and Plastics

Tailored Dynamic Viscoelasticity of Polyurethanes Based on Different Diols The development of damping and tire materials has led to a growing need to customize the dynamic viscoelasticity of polymers. In the case of polyurethane (PU), which possesses a designable molecular structure, the desired dynamic viscoelasticity can be achieved by carefully selecting flexible soft segments and employing chain extenders with diverse chemical structures. This process involves fine-tuning the molecular structure and optimizing the degree of micro-phase separation. It is worth noting that the temperature at which the loss peak occurs increases as the soft segment structure becomes more rigid. By incorporating soft segments with varying degrees of flexibility, the loss peak temperature can be adjusted within a broad range, from -50 °C to 14 °C. Furthermore, when the molecular structure of the chain extender becomes more regular, it enhances interaction between the soft and hard segments, leading to a higher degree of micro-phase separation. This phenomenon is evident from the increased percentage of hydrogen-bonding carbonyl, a lower loss peak temperature, and a higher modulus. By modifying the molecular weight of the chain extender, we can achieve precise control over the loss peak temperature, allowing us to regulate it within the range of -1 °C and 13 °C. To summarize, our research presents a novel approach for tailoring the dynamic viscoelasticity of PU materials and thus offers a new avenue for further exploration in this field. Viscoelasticity ; Materials science ; Dynamic modulus ; Dynamic mechanical analysis ; Flexibility (engineering) ; Polymer ; Polyurethane ; Composite material ; Molecular dynamics ; Phase (matter) ; Atmospheric temperature range ; Thermodynamics ; Chemistry ; Computational chemistry ; Mathematics ; Physics ; Organic chemistry Polymer composites and self-healing ; Polymer Nanocomposites and Properties ; Synthetic Organic Chemistry Methods
Authors: Jonas O. Wenzel | Israel Fernández | Frank Breher
Source: European Journal of Inorganic Chemistry (article, 2023-06-16)
Field: Chemistry — Organic Chemistry

Synthesis and Characterization of Bis(pyridylimino)isoindolide Alkali Metal Complexes in Three Redox States Abstract Non‐innocent ligands (NILs) like bis(pyridylimino)isoindolide (BPI) play crucial roles in coordination chemistry, biosciences, catalysis and material sciences. Investigating the isolated redox states of NILs is inevitable for understanding their redox‐activity and fine‐tuning the properties of corresponding metal complexes. The limited number of fundamental studies on the coordination behavior and redox chemistry of reduced BPI species is suggested to hamper further applications of the title compounds. This work describes for the first time the isolation of alkali metal complexes of BPI and Me 2 BPI in three different oxidation states and their characterization by means of NMR or EPR spectroscopy, DFT calculations, and SC‐XRD studies. The latter revealed the connection between bond orders in the ligand scaffold and its oxidation state. The paramagnetic compound Me 2 BPI‐K 2 was isolated as a coordination copolymer with 18‐crown‐6, which enabled the characterization of the dianionic BPI radical. Furthermore, the so‐far unknown trianionic state of BPI was reported by the isolation of BPI‐K 3 . This divulges an unprecedented bis(amidinato)isoindolide coordination mode. Chemistry ; Redox ; Oxidation state ; Electron paramagnetic resonance ; Coordination complex ; Catalysis ; Metal ; Characterization (materials science) ; Alkali metal ; Ligand (biochemistry) ; Polymer chemistry ; Combinatorial chemistry ; Crystallography ; Inorganic chemistry ; Nanotechnology ; Organic chemistry Oxidative Organic Chemistry Reactions ; Metal-Catalyzed Oxygenation Mechanisms ; Porphyrin and Phthalocyanine Chemistry
Authors: Changjun Zhang | Tingting Wei | Zhichen Yu | Yuxin Ding | Weike Su | Yuanyuan Xie
Source: RSC Advances (article, 2023-01-01)
Field: Chemistry — Organic Chemistry

Metal-free regioselective mono- and poly-halogenation of 2-substituted indazoles An unprecedented metal-free regioselective halogenation of 2<i>H</i>-indazoles has been revealed, which not only realized the highly selective synthesis of mono-halogenated products, but also completed poly-halogenations by fine tuning the reaction conditions. Various mono-/poly-/hetero-halogenated indazoles were obtained in moderate to excellent yields. Notably, this approach features environmentally friendly solvents, mild reaction conditions, simple execution and short reaction time. Halogenation ; Regioselectivity ; Environmentally friendly ; Chemistry ; Metal ; Reaction conditions ; Organic chemistry ; Combinatorial chemistry ; Catalysis Catalytic C–H Functionalization Methods ; Synthesis and Catalytic Reactions ; Catalytic Cross-Coupling Reactions
Authors: Michael Montag | David Milstein
Source: Israel Journal of Chemistry (article, 2023-07-28)
Field: Chemistry — Organic Chemistry

Catalytic Main‐Group Metal Complexes of Phosphine‐Based Pincer Ligands Abstract Pincer ligand complexes, which appeared nearly five decades ago, have provided a valuable platform for the study of fundamental chemical processes and the development of efficient catalysts for many chemical transformations. These complexes have usually contained transition metal atoms or ions, and their respective pincer ligands have often featured phosphine donor groups, which strongly coordinate to the metal center and allow its steric and electronic properties to be fine‐tuned. The increasing need to develop cost‐effective and sustainable catalytic processes has driven the search for main‐group metals as alternatives to commonly‐used transition metals. In this review, we show that despite the inherent mismatch between phosphines, which are soft Lewis bases, and main‐group metal ions, which are hard Lewis acids, a series of well‐defined phosphine‐based pincer complexes containing Li(I), Na(I), K(I), Mg(II), Ca(II), Zn(II) and Al(III) have been reported, which have proven to be active catalysts for industrially‐relevant transformations. Pincer movement ; Chemistry ; Phosphine ; Catalysis ; Transition metal ; Steric effects ; Main group element ; Lewis acids and bases ; Frustrated Lewis pair ; Ligand (biochemistry) ; Pincer ligand ; Metal ; Combinatorial chemistry ; Group (periodic table) ; Organic chemistry Organometallic Complex Synthesis and Catalysis ; Asymmetric Hydrogenation and Catalysis ; Organoboron and organosilicon chemistry
Authors: Mariusz Barczak | Dorota Pietras-Ożga | Moaaz K. Seliem | Giacomo de Falco | Dimitrios A. Giannakoudakis | Konstantinos S. Triantafyllidis
Source: Nanomaterials (article, 2023-07-13)
Field: Materials Science — Materials Chemistry

Mesoporous Silicas Obtained by Time-Controlled Co-Condensation: A Strategy for Tuning Structure and Sorption Properties Mesoporous silicas synthesized by the co-condensation of two and three different silica monomers were synthesized by varying the time intervals between the addition of individual monomers, while the total time interval was kept constant. This resulted in different structural properties of the final silicas, particularly in their porosity and local ordering. One of the obtained samples exhibited an unusual isotherm with two hysteresis loops and its total pore volume was as high as 2.2 cm<sup>3</sup>/g. In addition, to be thoroughly characterized by a wide range of instrumental techniques, the obtained materials were also employed as the adsorbents and release platforms of a diclofenac sodium (DICL; used here as a model drug). In the case of DICL adsorption and release, differences between the samples were also revealed, which confirms the fact that time control of a monomer addition can be successfully used to fine-tune the properties of organo-silica materials. Mesoporous material ; Monomer ; Sorption ; Materials science ; Porosity ; Chemical engineering ; Adsorption ; Condensation ; Mesoporous silica ; Diclofenac Sodium ; Hysteresis ; Chemistry ; Chromatography ; Organic chemistry ; Polymer ; Composite material ; Catalysis ; Thermodynamics Mesoporous Materials and Catalysis ; Covalent Organic Framework Applications ; Analytical Chemistry and Chromatography
Authors: J. Ashtami | P.V. Mohanan
Source: Journal of Materials Science (article, 2023-11-01)
Field: Materials Science — Materials Chemistry

Co-precipitation-hydrothermal mediated synthesis, characterization and toxicity evaluation of 2D Zn–Al LDHs in human osteoblast cells Layered double hydroxides ; Materials science ; Context (archaeology) ; Osteoblast ; Chemical engineering ; Precipitation ; Nanotechnology ; Coprecipitation ; Hydroxide ; Chemistry ; In vitro ; Biochemistry Layered Double Hydroxides Synthesis and Applications ; Bone Tissue Engineering Materials ; Covalent Organic Framework Applications
Authors: Yunchuan Qi | Mubarak Ayinla | Margaret J. Sobkowicz | Olof Ramström
Source: Macromolecular Rapid Communications (article, 2023-04-02)
Field: Materials Science — Biomaterials

Self‐Healable, Regenerable, and Degradable Dynamic Covalent Nitroalcohol Organogels Abstract Dynamic covalent gels are synthesized from an aromatic trialdehyde and α , ω ‐dinitroalkanes via the nitroaldol reaction in organic solvents. The gelation process can be fine‐tuned by changing the starting nitroalkanes, solvents, feed concentration, catalyst loading, or reaction temperature. The resulting organogels demonstrate good structural integrity and excellent self‐healing ability. Intact xerogels are produced upon drying, without damaging the network, and the solvent‐free network can recover its gel form in the presence of an organic solvent. Furthermore, the crosslinked dynameric gel depolymerize to small molecules in response to excess nitromethane. Nitromethane ; Covalent bond ; Dynamic covalent chemistry ; Solvent ; Self-healing ; Catalysis ; Materials science ; Chemical engineering ; Organic solvent ; Nitroaldol reaction ; Polymer chemistry ; Chemistry ; Molecule ; Organic chemistry ; Supramolecular chemistry ; Enantioselective synthesis Supramolecular Self-Assembly in Materials ; Covalent Organic Framework Applications ; Polydiacetylene-based materials and applications
Authors: Kamil Jastrzembski | Yingying Zhang | Lu Yang | Lukas Sporrer | Darius Pohl | Bernd Rellinghaus | Albrecht L. Waentig | Haojie Zhang | David Mücke | Shuai Fu | Miroslav Položij | Xue Li | Jianjun Zhang | Mingchao Wang | Ahiud Morag | Minghao Yu | Aurelio Mateo‐Alonso | Hai I. Wang | Mischa Bonn | Ute Kaiser | Thomas Heine | Renhao Dong⧫ | Xinliang Feng
Source: Small (article, 2023-12-11)
Field: Chemistry — Inorganic Chemistry

Tunable Crystallinity and Electron Conduction in Wavy 2D Conjugated Metal–Organic Frameworks via Halogen Substitution Currently, most reported 2D conjugated metal-organic frameworks (2D c-MOFs) are based on planar polycyclic aromatic hydrocarbons (PAHs) with symmetrical functional groups, limiting the possibility of introducing additional substituents to fine-tune the crystallinity and electrical properties. Herein, a novel class of wavy 2D c-MOFs with highly substituted, core-twisted hexahydroxy-hexa-cata-benzocoronenes (HH-cHBCs) as ligands is reported. By tailoring the substitution of the c-HBC ligands with electron-withdrawing groups (EWGs), such as fluorine, chlorine, and bromine, it is demonstrated that the crystallinity and electrical conductivity at the molecular level can be tuned. The theoretical calculations demonstrate that F-substitution leads to a more reversible coordination bonding between HH-cHBCs and copper metal center, due to smaller atomic size and stronger electron-withdrawing effect. As a result, the achieved F-substituted 2D c-MOF exhibits superior crystallinity, comprising ribbon-like single crystals up to tens of micrometers in length. Moreover, the F-substituted 2D c-MOF displays higher electrical conductivity (two orders of magnitude) and higher charge carrier mobility (almost three times) than the Cl-substituted one. This work provides a new molecular design strategy for the development of wavy 2D c-MOFs and opens a new route for tailoring the coordination reversibility by ligand substitution toward increased crystallinity and superior electric conductivity. Crystallinity ; Materials science ; Ligand (biochemistry) ; Halogen ; Conductivity ; Metal ; Electron mobility ; Conjugated system ; Crystallography ; Polymer ; Chemistry ; Physical chemistry ; Organic chemistry ; Optoelectronics Metal-Organic Frameworks: Synthesis and Applications ; Covalent Organic Framework Applications ; Graphene research and applications
Authors: Junghwa Lee | Pyoungsik Shin | Pi‐Tai Chou | Taiha Joo
Source: International Journal of Molecular Sciences (article, 2023-02-09)
Field: Chemistry — Physical and Theoretical Chemistry

Excited State Intramolecular Proton Transfer Dynamics of Derivatives of the Green Fluorescent Protein Chromophore Excited state intramolecular proton transfer (ESIPT) dynamics of the <i>o</i>-hydroxy analogs of the green fluorescent protein (GFP) chromophore have been investigated by time-resolved spectroscopies and theoretical calculations. These molecules comprise an excellent system to investigate the effect of electronic properties on the energetics and dynamics of ESIPT and to realize applications in photonics. Time-resolved fluorescence with high enough resolution was employed to record the dynamics and the nuclear wave packets in the excited product state exclusively in conjunction with quantum chemical methods. The ESIPT are ultrafast occurring in 30 fs for the compounds employed in this work. Although the ESIPT rates are not affected by the electronic properties of the substituents suggesting barrierless reaction, the energetics, their structures, subsequent dynamics following ESIPT, and possibly the product species are distinct. The results attest that fine tuning of the electronic properties of the compounds may modify the molecular dynamics of ESIPT and subsequent structural relaxation to achieve brighter emitters with broad tuning capabilities. Chromophore ; Intramolecular force ; Excited state ; Fluorescence ; Photochemistry ; Molecular dynamics ; Chemistry ; Chemical physics ; Relaxation (psychology) ; Proton ; Molecule ; Computational chemistry ; Atomic physics ; Stereochemistry ; Organic chemistry Photochemistry and Electron Transfer Studies ; Advanced Fluorescence Microscopy Techniques ; Photosynthetic Processes and Mechanisms
Authors: Shan Huang | Ying Liu | Pengcheng Huang | Fang–Ying Wu | Lanqun Mao
Source: Chemistry - A European Journal (article, 2023-03-23)
Field: Chemistry — Inorganic Chemistry

Exploring Zr‐Based Metal‐Organic Frameworks as Smart Electrochromic Sensors by Coordination‐Driven Surface Engineering As emerging stimuli-responsive materials, electrochromic metal-organic frameworks (MOFs) are still not utilized in sensing applications due to difficulties in water stability, facile synthesis and functionalization, and efficient translation of specific recognition events. Here, we firstly find that a Zr-based MOF furnished with postsynthetically created viologen-like electron-deficient moiety was electrochromic active. With a coordination-driven surface engineering strategy where phosphate-containing biomolecules are tethered to Zr nodes of the MOF, fine tuning the interface electron transfer was readily achieved, thus benefitting for constructing smart electrochromic sensors through the combination of the sensitivity of electrochemistry with the visuality of colorimetry. Particularly, MOF-coated conductive films enabled label-free detection of phosphoproteins, and aptamer-functionalized ones responded specifically to the target. In two cases distinct color changes allow for visual quantification. This study represents the first example of MOF-based electrochromic sensors developed by an efficient strategy, indicating the generality to electrochromic counterparts for various sensing applications. Electrochromism ; Materials science ; Surface modification ; Metal-organic framework ; Nanotechnology ; Electrochemistry ; Electron transfer ; Chemistry ; Photochemistry ; Electrode ; Organic chemistry Metal-Organic Frameworks: Synthesis and Applications ; Conducting polymers and applications ; Covalent Organic Framework Applications