jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Sourav Dey | Gunasekaran Velmurugan | Gopalan Rajaraman
Source: Dalton Transactions (article, 2019-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

How important is the coordinating atom in controlling magnetic anisotropy in uranium(<scp>iii</scp>) single-ion magnets? A theoretical perspective Theoretical investigation of actinide based nanomagnets is of paramount interest in the field of molecular magnetism as they offer remarkable properties compared to their lanthanide counterparts. Unlike lanthanides, the magnetic properties of actinides can be fine-tuned by modulating the ligand field as they possess a large metal-ligand covalency. In this regard, two complexes reported earlier have gained attention: [U(BcMe)<sub>3</sub>] (1) has been found to show Single-ion Magnet (SIM) characteristics whereas isomeric [U(BpMe)<sub>3</sub>] (2) does not exhibit any SIM behaviour. To unravel the origin of the differences observed in magnetic anisotropy, a detailed ab initio CASSCF study has been undertaken on the X-ray structure of complexes 1 and 2. Since actinide compounds exhibit strong covalency, the desired active space needs to be benchmarked to address this issue. Here, we have enlarged the active space systematically from CAS(3,7) to CAS(3,12) where all 5f electrons in 5f orbitals are sequentially expanded to include five formally empty 6d orbitals. Our calculations reveal that the incorporation of the 6d<sub>z<sup>2</sup></sub> orbital is vital in reproducing many experimental observables such as temperature dependent susceptibility, g-factors, ground state m<sub>J</sub> level, and ground-state-excited-state gap. Inclusion of this orbital in the reference space is found to describe better the UH-BH agostic interactions leading to significant variations in the computed parameters. Gaining from this understanding, we have carried out extensive bonding analysis within the DFT framework using tools such as Natural Bond Orbital (NBO) and Atoms In Molecule (AIM) to further probe these weak agostic interactions. Also, predictions to enhance the U-ligand covalency using U-sulphur bonds and the role of the U-C distance and C-U-C bite angles in the nature of anisotropy have been studied, and relevant magneto-structural correlations have been developed. Thus our results for the first time provide a comprehensive understanding of uranium based SMMs and offer ways to fine tune the anisotropy for experimental chemists. Lanthanide ; Natural bond orbital ; Agostic interaction ; Chemistry ; Atomic orbital ; Ligand field theory ; Magnetism ; Ground state ; Ab initio ; Magnetic anisotropy ; Atom (system on chip) ; Molecular orbital ; Ion ; Computational chemistry ; Atomic physics ; Magnetization ; Density functional theory ; Electron ; Molecule ; Condensed matter physics ; Physics ; Metal ; Magnetic field ; Nuclear physics Magnetism in coordination complexes ; Lanthanide and Transition Metal Complexes ; Radioactive element chemistry and processing
Authors: Gabriel M. Mercier | Koen Robeyns | Nikolay Tumanov | Benoı̂t Champagne | Johan Wouters | Tom Leyssens
Source: Crystal Growth & Design (article, 2019-08-28)
Field: Materials Science — Materials Chemistry

New Insights into Photochromic Properties of <i>N</i>-Salicylideneaniline Derivatives Using a Cocrystal Engineering Approach In this contribution, we aim to modify the photochromic properties of anils using a crystal engineering approach. Previous work has shown cocrystallization to alter the photochromic behavior of anils. Here, a full screening of 15 anil derivatives (including 8 newly described anils) with 21 coformers (carboxylic acids, amides, and halogenated benzene derivatives) was performed, resulting in 89 new anil cocrystals. This large amount of results allows drawing statistically valid insights on the complex photochromic mechanism providing evidence of a continuous phenomenon instead of the classic binary photochromic/nonphotochromic one. This is supported by the discovery of “weakly photochromic compounds” presented in this contribution. All the results allowed confirming that an enol-imine character is a requirement and that reducing the amount of short contacts involving the moieties of interest is an interesting way to fine-tune properties as this acts on both electronic and structural aspects. Following this “continuous hypothesis”, the role of the dihedral angle has been explored and shown to be related to the intensity of photochromism instead of being determinant for its occurrence. In addition, in this contribution, we present a novel way of interpreting DRS (diffuse reflectance spectroscopy) data. Photochromism ; Cocrystal ; Dihedral angle ; Chemistry ; Azobenzene ; Enol ; Imine ; Photochemistry ; Computational chemistry ; Organic chemistry ; Molecule ; Hydrogen bond ; Catalysis Photochromic and Fluorescence Chemistry ; Crystallography and molecular interactions ; Porphyrin and Phthalocyanine Chemistry
Authors: Yuhang Yao | Yu Rao | Yiwei Liu | Liang Jiang | Jin Xiong | Yingjie Fan | Zhen Shen | Jonathan L. Sessler | Jun‐Long Zhang
Source: Physical Chemistry Chemical Physics (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Aromaticity<i>versus</i>regioisomeric effect of β-substituents in porphyrinoids The photophysical properties of naturally occurring chlorophylls depend on the regioisomeric nature of the β-pyrrolic substituents. Such systems are the "gold standard" by which such effects are judged. However, simple extrapolations from what has been learned with chlorophylls may not be appropriate for other partially reduced porphyrinoids. Here we report the synthesis of a series of cis/trans-porphodilactones (cis/trans-1) and related derivatives (cis/trans 2-5) designed to probe the effect of regioisomeric substitution in porphyrinoids that incorporate degrees of unsaturation through the β-pyrrolic periphery that exceed those of chlorophyll. These test systems were obtained through β-pyrrolic modifications of the tetrapyrrolic core, which included reduction of β-diazalone to the corresponding dilactol moieties and 1,3-dipolar cycloadditions. In the case of cis- vs. trans-3 bearing two pyrrolidine-fused β-rings we found an unprecedented ΔQL up to ca. 71 nm (2086 cm-1), where ΔQL (QL means the lowest energy transfer band, also the S0 → S1 transition band, which is often assigned as Qy(0,0) band) refers to the transition energy difference between the corresponding cis/trans-isomers. The ΔQL values for these and other systems reported here were found to depend on the differences in the HOMO-LUMO energy gap and to be tied to the degeneracy and energy level splitting of the FMOs, as inferred from a combination of MCD spectral studies and DFT calculations. The aromaticity, estimated from the chemical shifts of the N-H protons and supported by theoretical calculations (e.g., AICD plots and NICS(1) values), was found to correlate with the extent of porphyrin periphery saturation resulting from the specific β-modifications. The aromaticity proved inversely proportional to the degree to which the regioisomerism affected the photophysical properties as noted from plots of ΔQLs in cm-1vs. the average NICS(1) values for 1-5. Such a finding is not something that can be easily interpolated from prior work and thus reveals how aromaticity may be used to fine-tune photophysical effects in reduced porphyrinoids. Aromaticity ; Chemistry ; Annulene ; Stereochemistry ; Computational chemistry ; Organic chemistry ; Molecule Porphyrin and Phthalocyanine Chemistry ; Photochemistry and Electron Transfer Studies ; Synthesis and Properties of Aromatic Compounds
Authors: Elmeri Lahtinen | Esa Kukkonen | Virva Kinnunen | Manu Lahtinen | Kimmo Kinnunen | Sari Suvanto | Ari Väisänen | Matti Haukka
Source: ACS Omega (article, 2019-10-01)
Field: Chemistry — Organic Chemistry

Gold Nanoparticles on 3D-Printed Filters: From Waste to Catalysts Three-dimensionally printed solid but highly porous polyamide-12 (PA12) plate-like filters were used as selective adsorbents for capturing tetrachloroaurate from acidic solutions and leachates to prepare PA12-Au composite catalysts. The polyamide-adsorbed tetrachloroaurate can be readily reduced to gold nanoparticles by using sodium borohydride, ascorbic acid, hydrogen peroxide, UV light, or by heating. All reduction methods led to polyamide-anchored nanoparticles with an even size distribution and high dispersion. The particle sizes were somewhat dependent on the reduction method, but the average diameters were typically about 20 nm. Particle sizes were determined by using a combination of single-particle inductively coupled plasma mass spectrometry, helium ion microscopy, and powder X-ray diffraction. Dispersion of the particles was analyzed by scanning electron microscopy with energy-dispersive spectroscopy. Due to the high adsorption selectivity of polyamide-12 toward tetrachloroaurate, the three-dimensional-printed filters were first used as selective gold scavengers for the acidic leachate of electronicwaste (WEEE). The supported nanoparticles were then generated directly on the filter via a simple reduction step. These objects were used as catalysts for the reduction of 4-nitrophenol to 4-aminophenol. The described method provides a direct route from waste to catalysts. The selective laser sintering method can be used to customize the flow properties of the catalytically active filter object, which allows the optimization of the porous catalytic object to meet the requirements of catalytic processes. Catalysis ; Nanoparticle ; Colloidal gold ; Materials science ; Waste management ; Nanotechnology ; Chemical engineering ; Business ; Chemistry ; Engineering ; Organic chemistry Nanomaterials for catalytic reactions ; Catalytic Processes in Materials Science ; Nanocluster Synthesis and Applications
Authors: Fei Han | T. P. Armstrong | Ana Andres-Arroyo | Danielle Bennett | Alexander H. Soeriyadi | Ali Alinezhad Chamazketi | Padmavathy Bakthavathsalam | Richard D. Tilley | J. Justin Gooding | Peter J. Reece
Source: Nanoscale (article, 2019-12-17)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Optical tweezers-based characterisation of gold core–satellite plasmonic nano-assemblies incorporating thermo-responsive polymers We report on the characterisation of the optical properties and dynamic behaviour of optically trapped single stimuli-responsive plasmonic nanoscale assemblies. Nano-assemblies consist of a core-satellite arrangement where the constituent nanoparticles are connected by the thermoresponsive polymer, poly(DEGA-co-OEGA). The optical tweezers allow the particles to be held isolated in solution and interrogated using dark-field spectroscopy. Additionally, controlling the optical trapping power provides localised heating for probing the thermal response of the nanostructures. Our results identify a number of distinct core-satellite configurations that can be stably trapped, which are verified using finite element modelling. Laser heating of the nanostructures through the trapping laser yields irreversible modification of the arrangement, as observed through the scattering spectrum. We consider which factors may be responsible for the observed behaviour in the context of the core-satellite geometry, polymer-solvent interaction, and the bonding of the nanoparticles. Plasmon ; Materials science ; Nano- ; Optical tweezers ; Core (optical fiber) ; Nanotechnology ; Polymer ; Satellite ; Tweezers ; Optoelectronics ; Optics ; Composite material ; Aerospace engineering ; Engineering ; Physics Gold and Silver Nanoparticles Synthesis and Applications ; Plasmonic and Surface Plasmon Research ; Orbital Angular Momentum in Optics
Authors: Pirmin Ganter | Bettina V. Lotsch
Source: Molecular Systems Design & Engineering (article, 2019-01-01)
Field: Chemistry — Organic Chemistry

Photonic nanoarchitectonics with stimuli-responsive 2D materials The emerging field of photonic nanoarchitectonics based on stimuli responsive 2D materials is highlighted with a focus on applications in colorimetric sensing. Photonics ; Nanotechnology ; Materials science ; Optoelectronics Polydiacetylene-based materials and applications ; Luminescence and Fluorescent Materials ; Advanced biosensing and bioanalysis techniques
Authors: Febriyani Damanik | Marzia Brunelli | Laura Pastorino | C. Ruggiero | Clemens van Blitterswijk | Joris I. Rotmans | Lorenzo Moroni
Source: Biomaterials Science (article, 2019-10-17)
Field: Materials Science — Surfaces, Coatings and Films

Sustained delivery of growth factors with high loading efficiency in a layer by layer assembly Layer by layer (LBL) assembly has garnered considerable interest due to its ability to generate multifunctional films with high tunability and versatility in terms of substrates and polyelectrolytes, allowing the option to use complex devices and drugs. Polyelectrolytes, such as growth factors (GFs), are essential, but costly, delicate, biological molecules that have been used in various tissue regeneration applications. For this reason, the controlled drug delivery of efficiently loaded GFs via LBL assembly (GF-LBL) can contribute to the establishment of cost-effective biologically triggered biomedical applications. We have developed an LBL method to load GFs (specifically, transforming growth factor beta 1, platelet-derived growth factor ββ, and insulin growth factor 1), with up to 90% efficiency approximately, by gas plasma surface activation and tuning the pH to increase the ionic strength of polyelectrolytes. Poly(styrenesulfonate) (PSS) and poly(ethyleneimine) (PEI) have been used to provide the initial necessary charge for multilayer build-up. Heparin and dextran sulphate have been investigated as counter polyelectrolytes to enhance the activity of GFs by protecting their ligands, where heparin resulted in the highest achievable loading efficiency for all GFs. Oxygen gas plasma and acidic pH levels also resulted in a significant increase in GF loading efficiency. The three GFs were released by diffusion and erosion in a controlled manner over lengthy time scales and the bioactivity was maintained for up to 14 days. When tested as implants in vitro, GF-LBL constructs increased fibroblast proliferation, influenced cell morphology and migration, and enhanced myofibroblast differentiation, indicating that the biological functionalities of the GFs were preserved. In conclusion, this developed LBL assembly method can provide a simple drug delivery system, which may yield more effective applications for tissue regeneration as well as biomedical sciences at large. Layer (electronics) ; Layer by layer ; Chemistry ; Nanotechnology ; Materials science Polymer Surface Interaction Studies ; Surface Modification and Superhydrophobicity ; Silk-based biomaterials and applications
Authors: Swarup Ghosh | Pascal M. Schäfer | Dennis Dittrich | Christoph Scheiper | Phillip Steiniger | Gerhard Fink | Agnieszka N. Ksiazkiewicz | Alexander Tjaberings | Christoph Wölper | André H. Gröschel | Andrij Pich | Sonja Herres‐Pawlis | Stephan Schulz
Source: ChemistryOpen (article, 2019-07-01)
Field: Materials Science — Biomaterials

Heterolepic <i>β</i>‐Ketoiminate Zinc Phenoxide Complexes as Efficient Catalysts for the Ring Opening Polymerization of Lactide Zinc phenoxide complexes L<sup>1</sup>ZnOAr <b>1</b>-<b>4</b> (L<sup>1</sup>=Me<sub>2</sub>NC<sub>2</sub>H<sub>4</sub>NC(Me)CHC(Me)O) and L<sup>2</sup>ZnOAr <b>5</b>-<b>8</b> (L<sup>2</sup>=Me<sub>2</sub>NC<sub>3</sub>H<sub>6</sub>NC(Me)CHC(Me)O) with donor-functionalized <i>β</i>-ketoiminate ligands (L<sup>1/2</sup>) and OAr substituents (Ar=Ph <b>1</b>, <b>5</b>; 2,6-Me<sub>2</sub>-C<sub>6</sub>H<sub>3</sub> <b>2</b>, <b>6</b>; 3,5-Me<sub>2</sub>-C<sub>6</sub>H<sub>3</sub> <b>3</b>, <b>7</b>; 4-Bu-C<sub>6</sub>H<sub>4</sub> <b>4</b>, <b>8</b>) with tuneable electronic and steric properties were synthesized and characterized. <b>1</b>-<b>8</b> adopt binuclear structures in the solid state except for <b>5</b>, while they are monomeric in CDCl<sub>3</sub> solution. <b>1</b>-<b>8</b> are active catalysts for the ring opening polymerization (ROP) of lactide (LA) in CH<sub>2</sub>Cl<sub>2</sub> at ambient temperature and the catalytic activity is controlled by the electronic and steric properties of the OAr substituent, yielding polymers with high average molecular weight (<i>M</i> <sub>n</sub>) and moderately controlled molecular weight distribution (MWDs). <b>1</b> and <b>5</b> showed a living polymerization character and kinetic studies on the ROP of <i>L</i>-LA with <b>1</b> and <b>5</b> proved first order dependencies on the monomer concentration. Homonuclear decoupled <sup>1</sup>H-NMR analyses of polylactic acid (PLA) formed with <i>rac</i>-LA proved isotactic enrichment of the PLA microstructure. Lactide ; Polymerization ; Ring-opening polymerization ; Polymer chemistry ; Monomer ; Steric effects ; Substituent ; Zinc ; Tacticity ; Catalysis ; Chemistry ; Molar mass distribution ; Polymer ; Polylactic acid ; Medicinal chemistry ; Stereochemistry ; Organic chemistry biodegradable polymer synthesis and properties ; Carbon dioxide utilization in catalysis ; Polyoxometalates: Synthesis and Applications
Authors: Marc Kielmann | Nitika Grover | W.W. Kalisch | Mathias O. Senge
Source: European Journal of Organic Chemistry (article, 2019-01-17)
Field: Materials Science — Materials Chemistry

Incremental Introduction of Organocatalytic Activity into Conformationally Engineered Porphyrins To study the correlation of macrocycle nonplanarity and catalytic activity of free base porphyrins in detail, a series of six tetraphenylporphyrins with graded degree of β‐ethyl substitution (“H 2 Et x TPPs” 1 – 6 ; x = 0, 2, 4, 6, 8) was applied in organocatalyzed reactions. The macrocycles display incrementally increasing nonplanarity due to repulsive peri ‐interactions. This creates an out‐of‐plane vector and better accessibility of the core amine and imine groups as the number of alkyl substituents increases. Following such a molecular engineering approach, the inner core system could be used to activate small molecules as a result of significant saddle distortion. The potential organocatalyst “H 2 Et x TPPs” were used in benchmark sulfa‐Michael reactions and we found a distinct relationship between nonplanarity and conversion. These observations were attributed to the combined effect of enhanced basicity and increased H‐bonding potential that could facilitate bifunctional organocatalysis. Ultimately, density functional theory (DFT) calculations were performed on 1 – 6 to monitor some electronic properties of the title compounds. Chemistry ; Bifunctional ; Organocatalysis ; Amine gas treating ; Imine ; Density functional theory ; Molecule ; Stereochemistry ; Computational chemistry ; Combinatorial chemistry ; Enantioselective synthesis ; Catalysis ; Organic chemistry Porphyrin and Phthalocyanine Chemistry ; Chemical Reaction Mechanisms ; Surface Chemistry and Catalysis
Authors: Patrick Wonner | T. Steinke | Stefan M. Huber
Source: Synlett (article, 2019-08-09)
Field: Chemistry — Organic Chemistry

Activation of Quinolines by Cationic Chalcogen Bond Donors The application of already established as well as novel selenium- and sulfur-based cationic chalcogen bond donors in the catalytic activation of quinoline derivatives is presented. In the presence of selected catalysts, rate accelerations of up to 2300 compared to virtually inactive reference compounds are observed. The catalyst loading can be reduced to 1 mol% while still achieving nearly full conversion for electron-poor and electron-rich quinolines. Contrary to expectations, preorganized catalysts were less active than the more flexible variants. Chemistry ; Chalcogen ; Cationic polymerization ; Catalysis ; Quinoline ; Sulfur ; Selenium ; Medicinal chemistry ; Combinatorial chemistry ; Organic chemistry Sulfur-Based Synthesis Techniques ; Organoselenium and organotellurium chemistry ; Asymmetric Synthesis and Catalysis
Authors: Franca De Sarno | Alfonso Maria Ponsiglione | Maria Russo | Anna Grimaldi | Ernesto Forte | Paolo A. Netti | Enza Torino
Source: Theranostics (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Water-Mediated Nanostructures for Enhanced MRI: Impact of Water Dynamics on Relaxometric Properties of Gd-DTPA Recently, rational design of a new class of contrast agents (CAs), based on biopolymers (hydrogels), have received considerable attention in Magnetic Resonance Imaging (MRI) diagnostic field. Several strategies have been adopted to improve relaxivity without chemical modification of the commercial CAs, however, understanding the MRI enhancement mechanism remains a challenge. <b>Methods:</b> A multidisciplinary approach is used to highlight the basic principles ruling biopolymer-CA interactions in the perspective of their influence on the relaxometric properties of the CA. Changes in polymer conformation and thermodynamic interactions of CAs and polymers in aqueous solutions are detected by isothermal titration calorimetric (ITC) measurements and later, these interactions are investigated at the molecular level using NMR to better understand the involved phenomena. Water molecular dynamics of these systems is also studied using Differential Scanning Calorimetry (DSC). To observe relaxometric properties variations, we have monitored the MRI enhancement of the examined structures over all the experiments. The study of polymer-CA solutions reveals that thermodynamic interactions between biopolymers and CAs could be used to improve MRI Gd-based CA efficiency. High-Pressure Homogenization is used to obtain nanoparticles. <b>Results:</b> The effect of the hydration of the hydrogel structure on the relaxometric properties, called Hydrodenticity and its application to the nanomedicine field, is exploited. The explanation of this concept takes place through several key aspects underlying biopolymer-CA's interactions mediated by the water. In addition, Hydrodenticity is applied to develop Gadolinium-based polymer nanovectors with size around 200 nm with improved MRI relaxation time (10-times). <b>Conclusions:</b> The experimental results indicate that the entrapment of metal chelates in hydrogel nanostructures offers a versatile platform for developing different high performing CAs for disease diagnosis. Biopolymer ; Relaxometry ; Polymer ; Self-healing hydrogels ; Gadolinium ; Differential scanning calorimetry ; Relaxation (psychology) ; Aqueous solution ; Nanoparticle ; Chemistry ; Molecular dynamics ; Materials science ; Chemical physics ; Nanotechnology ; Magnetic resonance imaging ; Thermodynamics ; Physical chemistry ; Computational chemistry ; Spin echo ; Polymer chemistry ; Organic chemistry Lanthanide and Transition Metal Complexes ; Advanced MRI Techniques and Applications ; MRI in cancer diagnosis