Showing papers on "Molecule published in 2020"
TL;DR: An efficient scheme for the in silico sampling for parts of the molecular chemical space by semiempirical tight-binding methods combined with a meta-dynamics driven search algorithm is proposed and discussed, opening many possible applications in modern computational chemistry and drug discovery.
Abstract: We propose and discuss an efficient scheme for the in silico sampling for parts of the molecular chemical space by semiempirical tight-binding methods combined with a meta-dynamics driven search algorithm. The focus of this work is set on the generation of proper thermodynamic ensembles at a quantum chemical level for conformers, but similar procedures for protonation states, tautomerism and non-covalent complex geometries are also discussed. The conformational ensembles consisting of all significantly populated minimum energy structures normally form the basis of further, mostly DFT computational work, such as the calculation of spectra or macroscopic properties. By using basic quantum chemical methods, electronic effects or possible bond breaking/formation are accounted for and a very reasonable initial energetic ranking of the candidate structures is obtained. Due to the huge computational speedup gained by the fast low-cost quantum chemical methods, overall short computation times even for systems with hundreds of atoms (typically drug-sized molecules) are achieved. Furthermore, specialized applications, such as sampling with implicit solvation models or constrained conformational sampling for transition-states, metal-, surface-, or noncovalently bound complexes are discussed, opening many possible applications in modern computational chemistry and drug discovery. The procedures have been implemented in a freely available computer code called CREST, that makes use of the fast and reliable GFNn-xTB methods.
671 citations
TL;DR: This Account gives a summary of the research on the molecular design of optoelectronic materials, with the consideration of a molecular uniting effect in different aggregated states, such as crystalline states, thin films, and nanoparticles.
Abstract: ConspectusOptoelectronic material properties are governed by the whole collective of organic moieties, and these aggregate states present the characteristic performance of extended assemblies with different molecular packing, not only of single molecules themselves. Thus, controlling molecular packing is an essential issue for obtaining the optimized optical and electronic properties. It is also a great challenge because of the unclear structures and complicated intermolecular interactions, including dispersion forces, electrostatic interactions and hydrogen bonding. Moreover, upon the introduction of some external force as the stimulus source, dynamic optical properties can be achieved with the transformation of molecular packing in some cases, such as the photoinduced room temperature phosphorescence (RTP) effect, mechanochromic luminescence, the thermal treatment-dependent mechanoluminescence effect, and the optimized nonlinear optical (NLO) property achieved after electric poling. Therefore, it is essential to understand the relation between characteristics of molecular packing and the resultant optoelectronic performance at the molecular level, which becomes increasingly demanding for the further development of functional materials for their applications in organic light-emitting diodes (OLEDs), chemo- and biosensors, organic solar cells, data storage, and anticounterfeiting devices.This Account gives a summary of our research on the molecular design of optoelectronic materials, with the consideration of a molecular uniting effect in different aggregated states, such as crystalline states, thin films, and nanoparticles. Through the systematical investigation of structure-packing-performance relationships, some strategies are afforded to partially control the molecular packing via the tunable size, shape, and configuration of aromatic moieties with different electronic and steric effects, together with different types of substituents as functional units to adjust the intermolecular interactions. The utilization of π-π interactions and hydrogen bonding by rational molecular design is considered as the key point to achieve the bright emission of organic materials, including the RTP and mechanoluminescence effects. Also, the dynamic optoelectronic properties are highlighted with different kinds of stimuli, including light irradiation, mechanical force, thermal treatment, and electric field, which are mainly related to the subtle molecular motions under external force and the changeable molecular packing as the metastable state. These selected examples will not only open a window for further development of organic and polymeric optoelectronic materials by the adjustable molecular packing and noncovalent interactions, but also prompt further advances for more interesting and exciting properties.
435 citations
TL;DR: The studies reveal that the nitrile (C-N) groups on the small molecule effectively reduce the trap density of the perovskite film and thus significantly suppresses the non-radiative recombination in the derived PVSC by passivating the Pb-exposed surface, resulting in an improved open-circuit voltage from 1.10 V to 1.16”V after passivation.
Abstract: All-inorganic perovskite solar cells (PVSCs) have drawn increasing attention because of their outstanding thermal stability. However, their performance is still inferior than the typical organic-inorganic counterparts, especially for the devices with p-i-n configuration. Herein, we successfully employ a Lewis base small molecule to passivate the inorganic perovskite film, and its derived PVSCs achieved a champion efficiency of 16.1% and a certificated efficiency of 15.6% with improved photostability, representing the most efficient inverted all-inorganic PVSCs to date. Our studies reveal that the nitrile (C-N) groups on the small molecule effectively reduce the trap density of the perovskite film and thus significantly suppresses the non-radiative recombination in the derived PVSC by passivating the Pb-exposed surface, resulting in an improved open-circuit voltage from 1.10 V to 1.16 V after passivation. This work provides an insight in the design of functional interlayers for improving efficiencies and stability of all-inorganic PVSCs. There has been a hot competition to optimize the device performance for all-inorganic perovskite solar cells. Here Wang et al. employ a Lewis base molecule to suppresses the non-radiative recombination in the inverted device and achieve a champion efficiency of 16.1%.
307 citations
TL;DR: In this paper, the authors investigated the adsorption performance of Ni-doped C3N (Ni-C3N) monolayer upon three SF6 decomposed species, including SO2, SOF2, and SO2F2.
210 citations
TL;DR: Wang et al. as discussed by the authors designed a facial strategy to synthesize N,P-doped defective carbon nanosheets first and then cover doped sites with well-define metal-N4 macrocyclic molecules through non-pyrolysis process.
Abstract: Experimental and computational studies show that topological defect and FeN4 site in carbon materials would deliver high performances for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Either defect or FeN4 site attracts numerous discussion, however, the synergetic effect between them is hardly explored. Herein, we design a facial strategy to synthesize N,P-doped defective carbon nanosheets first (N,P-DC), then cover doped sites with well-define metal-N4 macrocyclic molecules (FePc@N,P-DC) through non-pyrolysis process. The defective carbon boosts the high spin state of Fe center, thus brings superior ORR performances with the half-wave potential of 0.903 V and excellent cycling-life stability in alkaline media. Theoretical calculations show that the overpotential of FePc@N,P-DC for ORR is 0.52 V, much lower than 0.80 V (N,P-DC). Interestingly, the OER activity is simultaneously improved. This metal-Pc@defective carbon hybrid opens a door to develop electrocatalysts combining atomically metal-N4 sites with topological defect towards diverse energy conversion type.
185 citations
TL;DR: This review describes foundational subjects, methods, and metrics relevant to the energetic materials community and provides an overview of important classes of catenated nitrogen compounds ranging from theoretical investigation of hypothetical molecules to the practical application of real-world energetic materials.
Abstract: The properties of catenated nitrogen molecules, molecules containing internal chains of bonded nitrogen atoms, is of fundamental scientific interest in chemical structure and bonding, as nitrogen i...
134 citations
TL;DR: An interseting binuclear complex [Cd2(tcpa)4(bipy)2] (1) has been hydrothermally synthesized with 3, 5, 6-trichloropyridine phenoxy acetatic acid and 2, 2′-bipyridine coligands.
Abstract: An interseting binuclear complex [Cd2(tcpa)4(bipy)2] (1) has been hydrothermally synthesized with 3, 5, 6-trichloropyridine phenoxy acetatic acid (Htcpa) and 2, 2′-bipyridine (bipy) coligands. The X-ray single-crystal diffraction analysis shows that the CdII center is situated on unusual triangular prismatic geometry formed by two pyridyl nitrogen atoms of a bipy molecule and four carboxyl oxygen atoms of four different tcpa− ligands. The four tcpa− anions play as bis-monodentate linkers and connect two CdII ions together to form the dimer structure of 1. 1 is further assembled into a 2D layer by the co-effects of π···π stacking and Cl···Cl halogen bonds interactions. Moreover, 1 exhibits intense solid-state luminescence emissions centered at 442 nm at room temperature, which mainly originates from the intraligand π → π* transitions of tcpa−. The CCDC number of 1 is 1,935,091.
130 citations
TL;DR: A transformation in which an ‘ene’ reductase catalyses the visible-light-induced intermolecular radical hydroalkylation of alkenes gives carbonyl compounds with a remote stereocentre in high yield and enantioselectivity, which otherwise are difficult to access using chemocatalysis.
Abstract: Enzymes are increasingly explored for use in asymmetric synthesis1-3, but their applications are generally limited by the reactions available to naturally occurring enzymes. Recently, interest in photocatalysis4 has spurred the discovery of novel reactivity from known enzymes5. However, so far photoinduced enzymatic catalysis6 has not been used for the cross-coupling of two molecules. For example, the intermolecular coupling of alkenes with α-halo carbonyl compounds through a visible-light-induced radical hydroalkylation, which could provide access to important γ-chiral carbonyl compounds, has not yet been achieved by enzymes. The major challenges are the inherent poor photoreactivity of enzymes and the difficulty in achieving stereochemical control of the remote prochiral radical intermediate7. Here we report a visible-light-induced intermolecular radical hydroalkylation of terminal alkenes that does not occur naturally, catalysed by an 'ene' reductase using readily available α-halo carbonyl compounds as reactants. This method provides an efficient approach to the synthesis of various carbonyl compounds bearing a γ-stereocentre with excellent yields and enantioselectivities (up to 99 per cent yield with 99 per cent enantiomeric excess), which otherwise are difficult to access using chemocatalysis. Mechanistic studies suggest that the formation of the complex of the substrates (α-halo carbonyl compounds) and the 'ene' reductase triggers the enantioselective photoinduced radical reaction. Our work further expands the reactivity repertoire of biocatalytic, synthetically useful asymmetric transformations by the merger of photocatalysis and enzyme catalysis.
130 citations
TL;DR: The theoretical calculations of Benzyl-3-N-(2,4,5-trimethoxyphenylmethylene)hydrazinecarbodithioate and in silico studies predicted that the compound has good drug like character.
124 citations
TL;DR: Amplification of chiral molecular information from molecules to materials-level structures and the creation of chirality from achiral components upon temporal statistic fluctuations are universal, regardless of the nature of the assemblies and are thus surely advantageous characteristics for a wide range of applications.
Abstract: Exploration of molecular functions and material properties based on the control of chirality would be a scientifically elegant approach. Here, the fabrication and function of chiral-featured materials from both chiral and achiral components using a supramolecular nanoarchitectonics concept are discussed. The contents are classified in to three topics: i) chiral nanoarchitectonics of rather general molecular assemblies; ii) chiral nanoarchitectonics of metal-organic frameworks (MOFs); iii) chiral nanoarchitectonics in liquid crystals. MOF structures are based on nanoscopically well-defined coordinations, while mesoscopic orientations of liquid-crystalline phases are often flexibly altered. Discussion on the effects and features in these representative materials systems with totally different natures reveals the universal importance of supramolecular chiral nanoarchitectonics. Amplification of chiral molecular information from molecules to materials-level structures and the creation of chirality from achiral components upon temporal statistic fluctuations are universal, regardless of the nature of the assemblies. These features are thus surely advantageous characteristics for a wide range of applications.
124 citations
TL;DR: The field of molecular transition metal complexes as well as recent boron examples for the formation of nitrogen-element bonds are surveyed, highlighting that the challenge for catalytic chemistry is not in the reactivity of coordinated dinitrogen but rather removal of the functionalized ligand from the coordination sphere of the metal.
Abstract: The functionalization of coordinated dinitrogen to form nitrogen–element bonds en route to nitrogen-containing molecules is a long-standing challenge in chemical synthesis. The strong triple bond a...
TL;DR: Radiation-enhanced polycrystalline perovskite films with ultralong carrier lifetimes exceeding 6 μs and single-crystal-like electron-hole diffusion lengths of more than 5 μm are achieved and the weakening of the electron-phonon coupling and the excitonic features of the photogenerated carriers in the optimized films, which together contribute to the enhancement of carrier separation and transportation, are confirmed.
Abstract: Lead halide perovskite films have witnessed rapid progress in optoelectronic devices, whereas polycrystalline heterogeneities and serious native defects in films are still responsible for undesired recombination pathways, causing insufficient utilization of photon-generated charge carriers. Here, radiation-enhanced polycrystalline perovskite films with ultralong carrier lifetimes exceeding 6 μs and single-crystal-like electron-hole diffusion lengths of more than 5 μm are achieved. Prolongation of charge-carrier activities is attributed to the electronic structure regulation and the defect elimination at crystal boundaries in the perovskite with the introduction of phenylmethylammonium iodide. The introduced electron-rich anchor molecules around the host crystals prefer to fill the halide/organic vacancies at the boundaries, rather than form low-dimensional phases or be inserted into the original lattice. The weakening of the electron-phonon coupling and the excitonic features of the photogenerated carriers in the optimized films, which together contribute to the enhancement of carrier separation and transportation, are further confirmed. Finally the resultant perovskite films in fully operating solar cells with champion efficiency of 23.32% are validated and a minimum voltage deficit of 0.39 V is realized.
TL;DR: This work shows that for nanoparticles capped with complementary reactive polymers, a stoichiometric reaction leads to reorganization of the uniform ligand shell and self-limiting nanoparticle bonding, whereas electrostatic repulsion between colloidal bonds governs CM symmetry.
Abstract: Nanoparticle clusters with molecular-like configurations are an emerging class of colloidal materials. Particles decorated with attractive surface patches acting as analogs of functional groups are used to assemble colloidal molecules (CMs); however, high-yield generation of patchy nanoparticles remains a challenge. We show that for nanoparticles capped with complementary reactive polymers, a stoichiometric reaction leads to reorganization of the uniform ligand shell and self-limiting nanoparticle bonding, whereas electrostatic repulsion between colloidal bonds governs CM symmetry. This mechanism enables high-yield CM generation and their programmable organization in hierarchical nanostructures. Our work bridges the gap between covalent bonding taking place at an atomic level and colloidal bonding occurring at the length scale two orders of magnitude larger and broadens the methods for nanomaterial fabrication.
TL;DR: In this article, a kind of 2D-layered material, Ti3C2 MXenes, was successfully used as a new and efficient co-catalyst to improve the photocatalytic NH3 synthesis performance of P25.
Abstract: A kind of 2D-layered material, Ti3C2 MXenes, was successfully used as a new and efficient co-catalyst to improve the photocatalytic NH3 synthesis performance of P25, due to its large surface area/2D-layered structure, large electric capacity, excellent electrical conductivity and effective chemisorption/activation of N2 molecules. The generation yield of NH3 was improved by five times on the optimized sample of 6% Ti3C2 MXenes–P25 compared with pure P25 under full spectrum light irradiation, consistent with the measured both photocurrent densities and charge lifetime. The further mechanistic study showed that Ti3C2 MXenes played an important role in the separation of photogenerated electron–hole pairs by accumulating the excited electrons from the excited P25. Most importantly, Ti3C2 MXenes could dramatically improve chemisorption and activation of N2 as demonstrated by ESR spectra and DFT calculations. In addition, Ti3C2 MXenes loading on P25 could introduce oxygen vacancies in P25, also beneficial for photocatalytic NH3 synthesis. Thus this study provides an efficient and promising co-catalyst for the photocatalytic NH3 synthesis process from N2 in air
TL;DR: In this paper, the authors demonstrate that the use of proper ro-vibronic transitions enables laser cooling of nonlinear polyatomic molecules, thereby opening a path to efficient cooling of chiral molecules and, eventually, optical tweezer arrays of complex polyatomic species.
Abstract: Ultracold polyatomic molecules have potentially wide-ranging applications in quantum simulation and computation, particle physics, and quantum chemistry. For atoms and small molecules, direct laser cooling has proven to be a powerful tool for quantum science in the ultracold regime. However, the feasibility of laser-cooling larger, nonlinear polyatomic molecules has remained unknown because of their complex structure. We laser-cooled the symmetric top molecule calcium monomethoxide (CaOCH3), reducing the temperature of ~104 molecules from 22 ± 1 millikelvin to 1.8 ± 0.7 millikelvin in one dimension and state-selectively cooling two nuclear spin isomers. These results demonstrate that the use of proper ro-vibronic transitions enables laser cooling of nonlinear molecules, thereby opening a path to efficient cooling of chiral molecules and, eventually, optical tweezer arrays of complex polyatomic species.
TL;DR: ELF method is not only useful for the characterization of covalent bonds but a lot of information can be extracted also for weaker types of binding, from the charge integration over the interaction region(s) can reveal the strength of the bonding/binding ranging from the triple bonds to weak dispersion.
Abstract: To distinguish between chemical bonding and physical binding is usually simple. They differ, in the normal case, in both interaction strength (binding energy) and interaction length (structure). However, chemical bonding can be weak (e.g. in some metallic bonding) and physical binding can be strong (e.g. due to permanent electrostatic moments, hydrogen binding, etc) making differentiation non-trivial. But since these are shared-electron or unshared-electron interactions, respectively, it is in principle possible to distinguish the type of interaction by analyzing the electron density around the interaction point(s)/interface. After all, the former should be a contact while the latter should be a tunneling barrier. Here, we investigate within the framework of density functional theory typical molecules and crystals to show the behaviour of the electron localization function (ELF) in different shared-electron interactions, such as chemical (covalent) and metallic bonding and compare to unshared-electron interactions typical for physical binding, such as ionic, hydrogen and Keesom, dispersion (van der Waals) binding and attempt to categorise them only by the ELF and the electron population in the interaction region. It is found that the ELF method is not only useful for the characterization of covalent bonds but a lot of information can be extracted also for weaker types of binding. Furthermore, the charge integration over the interaction region(s) and tracing the ELF profile can reveal the strength of the bonding/binding ranging from the triple bonds to weak dispersion.
TL;DR: The characterization of folding energy landscapes at high resolution, studies of structurally complex multidomain proteins, folding in the presence of chaperones, and the ability to investigate real-time cotranslational folding of a polypeptide are described.
Abstract: Manipulation of individual molecules with optical tweezers provides a powerful means of interrogating the structure and folding of proteins Mechanical force is not only a relevant quantity in cellular protein folding and function, but also a convenient parameter for biophysical folding studies Optical tweezers offer precise control in the force range relevant for protein folding and unfolding, from which single-molecule kinetic and thermodynamic information about these processes can be extracted In this review, we describe both physical principles and practical aspects of optical tweezers measurements and discuss recent advances in the use of this technique for the study of protein folding In particular, we describe the characterization of folding energy landscapes at high resolution, studies of structurally complex multidomain proteins, folding in the presence of chaperones, and the ability to investigate real-time cotranslational folding of a polypeptide
01 May 2020
TL;DR: In this article, a strategy for C-O bond activation by doping the surface of moderately reducible oxides with an ultralow loading of noble metals was proposed. But the results showed that the Pt on the TiO2 surface is more active than metallic sites.
Abstract: Selective C–O activation of multifunctional molecules is essential for many important chemical processes. Although reducible metal oxides are active and selective towards reductive C–O bond scission via the reverse Mars–van Krevelen mechanism, the most active oxides undergo bulk reduction during reaction. Here, motivated by the enhanced oxide reducibility by metals, we report a strategy for C–O bond activation by doping the surface of moderately reducible oxides with an ultralow loading of noble metals. We demonstrate the principle using highly dispersed Pt anchored onto TiO2 for furfuryl alcohol conversion to 2-methylfuran. A combination of density functional theory calculations, catalyst characterization (scanning transmission electron microscopy, electron paramagnetic resonance, Fourier-transform infrared spectroscopy and X-ray absorption spectroscopy), kinetic experiments and microkinetic modelling expose substantial C–O activation rate enhancement, without bulk catalyst reduction or unselective ring hydrogenation. A methodology is introduced to quantify various types of sites, revealing that the cationic redox Pt on the TiO2 surface is more active than metallic sites for C–O bond activation. Reducible metal oxides selectively catalyse the hydrodeoxygenation of C–O bonds in bio-based aromatic molecules, although they show limited performance. Now, using TiO2 as an example, a method is reported to enhance the activity of the oxide by surface doping with an ultralow loading of Pt.
TL;DR: The di-anion surface created in this study, with atomic mixing of active sites and reactant dragging functionalities, represents a effective di-functional interface for boosted kinetic performance in the electrocatalytic H2 evolution activities.
Abstract: Engineering the reaction interface to preferentially attract reactants to inner Helmholtz plane is highly desirable for kinetic advancement of most electro-catalysis processes, including hydrogen evolution reaction (HER). This, however, has rarely been achieved due to the inherent complexity for precise surface manipulation down to molecule level. Here, we build a MoS2 di-anionic surface with controlled molecular substitution of S sites by –OH. We confirm the –OH group endows the interface with reactant dragging functionality, through forming strong non-covalent hydrogen bonding to the reactants (hydronium ions or water). The well-conditioned surface, in conjunction with activated sulfur atoms (by heteroatom metal doping) as active sites, giving rise to up-to-date the lowest over potential and highest intrinsic activity among all the MoS2 based catalysts. The di-anion surface created in this study, with atomic mixing of active sites and reactant dragging functionalities, represents a effective di-functional interface for boosted kinetic performance. H2 energy as an alternative to fossil fuels requires cost-effective catalysts with fast kinetics for splitting water. Here, authors design MoS2 materials with di-anionic surfaces to improve the electrocatalytic H2 evolution activities.
TL;DR: In this article, a density functional theory was employed to investigate the corrosion inhibition mechanisms of four amino acids, viz. glutamic acid, cysteine, glycine, and their derivative glutathione.
TL;DR: The advantages of ultralow cost and high universality enable a great practical application potential of the super-concentrated sugar-based aqueous electrolytes, which can also provide great experimental and theoretical assistance for further research in water chemistry.
Abstract: Aqueous energy-storage systems have attracted wide attention due to their advantages such as high security, low cost, and environmental friendliness. However, the specific chemical properties of water induce the problems of narrow electrochemical stability window, low stability of water-electrode interface reactions, and dissolution of electrode materials and intermediate products. Therefore, new low-cost aqueous electrolytes with different water chemistry are required. The nature of water depends largely on its hydroxyl-based hydrogen bonding structure. Therefore, the super-concentrated hydroxyl-rich sugar solutions are designed to change the original hydrogen bonding structure of water. The super-concentrated sugars can reduce the free water molecules and destroy the tetrahedral structure, thus lowering the binding degree of water molecules by breaking the hydrogen bonds. The ionic electrolytes based on super-concentrated sugars have the expanded electrochemical stability window (up to 2.812 V), wide temperature adaptability (-50 to 80 °C), and fair ionic conductivity (8.536 mS cm-1 ). Aqueous lithium-, sodium-, potassium-ion batteries and supercapacitors using super-concentrated sugar-based electrolytes demonstrate an excellent electrochemical performance. The advantages of ultralow cost and high universality enable a great practical application potential of the super-concentrated sugar-based aqueous electrolytes, which can also provide great experimental and theoretical assistance for further research in water chemistry.
TL;DR: For the first time, the surface-enhanced infrared absorption spectroscopy is applied to directly monitor the vibrational behaviors of adsorbed hydrogen atoms and interfacial water molecules on Pt surfaces in a wide pH window from 1.1 to 12.9.
Abstract: The origins of the pH-dependent kinetics of hydrogen evolution and oxidation reactions on Pt surfaces are unsolved dilemmas that have lasted for over half a century. In this study, surface-enhanced infrared absorption spectroscopy is applied to directly monitor the vibrational behaviors of adsorbed hydrogen atoms and interfacial water molecules on Pt surfaces in a wide pH window from 1.1 to 12.9. For the first time, we successfully measure the pH-dependent changes of hydrogen and water binding strength according to their vibrational wavenumbers, which are both monotonously weakened as the solution pH increases. Their changes are the net results of altered electrochemical interface environments and are important contributions to the pH-dependent hydrogen reaction kinetics. Our results add significant new insights into the role of interfacial environments on electrocatalysis.
TL;DR: In this paper, copper ions (Cu2+) chelated mesoporous silica nanoparticles (MSNs) via dopamine chemistry (AZOX@MSNs-PDA-Cu) for controlled azoxystrobin (AZoxide) release have been developed.
TL;DR: The effect of molecular lignin structure on thermomechanical properties was analyzed, finding significant differences between the rigid guaiacyl units in spruce lignIn compared with sinapyl units in eucalyptus lign in.
TL;DR: In this paper, a new coordination polymer [Mn(3, 5, 6-tcpa)2(2, 2′-bipy)]n (1) has been synthesized by the hydrothermal reaction of manganese sulfate hydrate with 3, 5 and 6-trichloropyridine-2-oxyacetic acid (3, 4, 6, Htcpa)-coligands.
TL;DR: PAH[4]’s unique properties of a high water/solute permselectivity via cooperative water-wire formation could usher in an alternative design paradigm for permeable membrane materials in separations, energy production and barrier applications.
Abstract: Artificial water channels are synthetic molecules that aim to mimic the structural and functional features of biological water channels (aquaporins). Here we report on a cluster-forming organic nanoarchitecture, peptide-appended hybrid[4]arene (PAH[4]), as a new class of artificial water channels. Fluorescence experiments and simulations demonstrated that PAH[4]s can form, through lateral diffusion, clusters in lipid membranes that provide synergistic membrane-spanning paths for a rapid and selective water permeation through water-wire networks. Quantitative transport studies revealed that PAH[4]s can transport >109 water molecules per second per molecule, which is comparable to aquaporin water channels. The performance of these channels exceeds the upper bound limit of current desalination membranes by a factor of ~104, as illustrated by the water/NaCl permeability-selectivity trade-off curve. PAH[4]'s unique properties of a high water/solute permselectivity via cooperative water-wire formation could usher in an alternative design paradigm for permeable membrane materials in separations, energy production and barrier applications.
TL;DR: The following article is the first attempt to investigate the supramolecular structure of cellulose with the varied moisture content by the means of Fourier-transform and near infrared spectroscopy techniques and proposed that some deconvoluted signals from the region of 3000–2750 cm−1 might be assigned to the hydroxyl group-incorporated hydrogen bonding.
Abstract: The following article is the first attempt to investigate the supramolecular structure of cellulose with the varied moisture content by the means of Fourier-transform and near infrared spectroscopy techniques. Moreover, authors aimed at the detailed and precise presentation of IR spectra interpretation approach in order to create a reliable guideline for other researchers. On the basis of obtained data, factors indicating biopolymer crystallinity and development of hydrogen interactions were calculated and the peaks representing hydrogen bonding (7500-6000 cm-1, 3700-3000 cm-1, and 1750-1550 cm-1) were resolved using the Gaussian distribution function. Then, the deconvoluted signals have been assigned to the specific interactions occurring at the supramolecular level and the hydrogen bond length, as well bonding-energy were established. Furthermore, not only was the water molecules adsorption observed, but also the possibility of the 3OH⋯O5 intramolecular hydrogen bond shortening in the wet state was found-from (27,786 ± 2) 10-5 nm to (27,770 ± 5) 10-5 nm. Additionally, it was proposed that some deconvoluted signals from the region of 3000-2750 cm-1 might be assigned to the hydroxyl group-incorporated hydrogen bonding, which is, undoubtedly, a scientific novelty as the peak was not resolved before.
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TL;DR: This dataset will assist benchmarking and transfer learning in two classes of tasks: inferring 3D properties from 2D molecular graphs, and developing generative models to sample 3D conformations.
Abstract: Machine learning (ML) outperforms traditional approaches in many molecular design tasks. ML models usually predict molecular properties from a 2D chemical graph or a single 3D structure, but neither of these representations accounts for the ensemble of 3D conformers accessible to a molecule. Property prediction could be improved by using conformer ensembles as input, but there is no large-scale dataset that contains graphs annotated with high-quality conformers and experimental data. Here we use first-principles simulations to generate accurate conformers for over 430,000 molecules, including 300,000 with experimental data for the inhibition of various pathogens. The Geometric Ensemble Of Molecules (GEOM) dataset contains over 33 million molecular conformers labeled with their relative energies and statistical probabilities at room temperature. GEOM will assist in the development of models that predict properties from conformer ensembles, and generative models that sample 3D conformations.
TL;DR: The catalytic mechanism of generating different CX bonds is further discussed according to both structural features of MOFs and the interactions among CO2 , substrates, as well as MOFs.
Abstract: Transformation of CO2 based on metal-organic framework (MOF) catalysts is becoming a hot research topic, not only because it will help to reduce greenhouse gas emission, but also because it will allow for the production of valuable chemicals. In addition, a large number of impressive products have been synthesized by utilizing CO2 . In fact, it is the formation of new covalent bonds between CO2 and substrate molecules that successfully result in CO2 solidly inserting into the products, and only four types of new CX bonds, including CH, CC, CN, and CO bonds, are observed in this exploration. An overview of recent progress in constructing CX bonds for CO2 conversion catalyzed by various MOF catalysts is provided. The catalytic mechanism of generating different CX bonds is further discussed according to both structural features of MOFs and the interactions among CO2 , substrates, as well as MOFs. The future opportunities and challenges in this field are also tentatively covered.
TL;DR: The proposed StackCPPred can be a powerful tool for predicting CPPs and their uptake efficiency, facilitating hypothesis-driven experimental design and accelerating their applications in clinical therapy.
Abstract: Motivation Cell-penetrating peptides (CPPs) are a vehicle for transporting into living cells pharmacologically active molecules, such as short interfering RNAs, nanoparticles, plasmid DNAs and small peptides, thus offering great potential as future therapeutics. Existing experimental techniques for identifying CPPs are time-consuming and expensive. Thus, the prediction of CPPs from peptide sequences by using computational methods can be useful to annotate and guide the experimental process quickly. Many machine learning-based methods have recently emerged for identifying CPPs. Although considerable progress has been made, existing methods still have low feature representation capabilities, thereby limiting further performance improvements. Results We propose a method called StackCPPred, which proposes three feature methods on the basis of the pairwise energy content of the residue as follows: RECM-composition, PseRECM and RECM-DWT. These features are used to train stacking-based machine learning methods to effectively predict CPPs. On the basis of the CPP924 and CPPsite3 datasets with jackknife validation, StackDPPred achieved 94.5% and 78.3% accuracy, which was 2.9% and 5.8% higher than the state-of-the-art CPP predictors, respectively. StackCPPred can be a powerful tool for predicting CPPs and their uptake efficiency, facilitating hypothesis-driven experimental design and accelerating their applications in clinical therapy. Availability and implementation Source code and data can be downloaded from https://github.com/Excelsior511/StackCPPred. Supplementary information Supplementary data are available at Bioinformatics online.