Graphene materials have a demonstrated value in water treatment. Efforts to promote these materials are focused on the generation of functional graphene adsorbents for effectively removing contaminants from water. Here, inspired by the conformation of spider silks, we present a novel graphene microfiber material with spindle-knotted microstructures by using a microfluidic emulsification and spinning collaborative technology. Read More
Nafion®/phosphotungstic acid composite membrane and impact of varying concentration of heteropoly acid (HPA) on the well-known effective mechanisms of proton transport were investigated using classical and quantum hopping molecular dynamics simulation. Our simulations demonstrated that the HPA particles exhibited a favorable influence on Grotthuss mechanism in proton transportation at low hydration levels. From radial distribution function examinations, it was found that HPA particles were solvated with water and also exhibited stronger affinity toward hydronium ions. Read More
First principles electronic structure calculations based on density functional theory (DFT) framework are performed to investigate hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on two-dimensional Al2C monolayer. The monolayer is functionalized with several dopants and four prominent doping elements are nitrogen (N), phosphorous (P), boron (B) and sulphur (S). After determining the individual adsorption energy of hydrogen and oxygen on different functionalized Al2C monolayer, the adsorption free energies are predicted subsequently for each of the functionalized cases in order to predict which case of functionalization serves better for HER or OER. Read More
Indian Institute of Technology Madras, Department of Chemistry, Department of Chemistry, Indian Institute of Technology Madras, 600036, Chennai, INDIA.
Correlation of the structure and properties of ionic liquids (ILs) is essential for the development of optimized materials in the fields of gas capture and separation, battery electrolyte, and cellulose dissolution process. In view of this, a detailed vibrational spectroscopic analysis and quantum-chemical calculation were performed to explore the interionic interactions in N-methylpyrrolidone cation and carboxylate anion-based ILs. FTIR and Raman spectroscopy were applied to identify the H-bonding interactions between ion-pair, in which red-shifted vibrational modes were evidenced as a function of anion chain length. Read More
ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, 8093, Zurich, SWITZERLAND.
Cyclic peptides have regained interest as potential inhibitors of challenging targets, but have often a low bioavailability. The natural product cyclosporine A (CsA) is the textbook exception. Despite its size and polar backbone it is able to passively cross membranes. Read More
Dalian University of Technology, Ling gong street, 116024, Dalian, CHINA.
It was found that bands at 739, 963 and 1107 cm-1 in resonant Raman spectra are characteristics of framework penta-coordinated NbV-OH species, and that band at 1336 cm-1 in UV Raman spectra excited by 320 nm is a sensitive detector to identify extraframework niobium species. The change of framework penta-coordinated NbV-OH species into Nb+ and NbO- species due to dehydration was definitively confirmed based on UV resonance Raman and UV/Vis results. Read More
University of Nevada Las Vegas, Physics and Astronomy Department, 4505 Maryland pk way, 89154, Las Vegas, UNITED STATES.
The thermoelectric properties of polycrystalline SnTe have been measured up to 4.5 GPa at 330 K. SnTe shows an enormous enhancement in Seebeck coefficient greater than 200% after 3 GPa, which correlates to a known pressure-induced structural phase transition that is observed through simultaneous in-situ X-ray diffraction measurement. Read More
Kagome lattices have attracted much attention due to their potential applications in spin-frustrated magnetism and host-guest chemistry. Examples toward the fabrication of 2D Kagome lattices reported previously have a common feature that the precursor molecules were typically structurally intact on surface with no chemical reactions accompanied. Herein, with the combined synchrotron radiation photoelectron spectroscopy (SRPES) and scanning tunneling microscopy (STM), we demonstrated that two types of chiral Kagome lattices from on-surface synthesized organometallic compounds were fabricated, which are known as intermediates of Glaser coupling on silver single crystal surfaces. Read More
The development of non-precious-metal electrocatalysts with high activity, stability and low-cost towards oxygen reduction reaction remains a great challenge. The heteroatom-doped carbon materials as effective catalysts obtained increasing research attention. However, the uncontrollable doping type of heteroatoms in carbon matrix inhibited the catalysts' activity. Read More
Well-defined Fe(II)-terpyridyl monolayers were fabricated on SiOx and conductive ITO-coated glass substrates via covalent bond formation between the metallo-organic complexes and a pre-assembled coupling layer. Three different homo- and heteroleptic complexes with the terminal pyridyl, amine, and phenyl groups were tested. All the films were found to be densely packed, homogeneous, and consisting of upright standing molecules. Read More
Dimethoxydimethylsilane (DODSi) is developed as an interface stabilizing additive by a selective HF scavenging reaction for layered Ni-rich oxide cathodes. Ex-situ NMR analyses demonstrated that DODSi effectively removes HF in the electrolyte based on the matched chemical reactivity of Si with F- and O with H+. The cells employing DODSi exhibit higher specific capacity with retention than those cycled with a DODSi-free electrolyte even under an in-situ HF generating environment. Read More
We have performed surface science model studies scrutinizing the interaction of ester-functionalized ionic liquids(ILs) with atomically defined Co3O4(111) and CoO(100) surfaces. Thin films of three ILs, 3-butyl-1-methyl imidazolium bis(trifluoromethyl-sulfonyl) imide ([BMIM][NTf2]), 3-(4-methoxyl-4-oxobutyl)-1-methylimidazolium bis(trifluoromethyl-sulfonyl) imide ([MBMIM][NTf2]), and 3-(4-iso¬propoxy-4-oxobutyl)-1-methylimidazolium bis(trifluoromethyl-sulfonyl) imide ([IPBMIM][NTf2]), were deposited on these surfaces by physical vapor deposition. Time-resolved and temperature-programmed infrared reflection absorption spectroscopy (TR-IRAS, TP-IRAS) were applied to monitor in-situ the adsorption, film growth and thermally induced desorption. Read More
Instituto de Quimica Medica, IQM, Juan de la Cierva, 3, 28006, Madrid, SPAIN.
In this manuscript we have explored the competition between hydrogen- (HB) and halogen-bonded (XB) 4-amonium pyridine and halogenamonium (NHnF3-nX+, n=0-3, X= F, Cl, Br and I) cation-cation complexes by means of DFT theoretical calculations. HB and XB minima structures are found for all systems in gas phase. As the number of fluorine atoms increases the HB complexes are more favored than the XB ones. Read More
The influence of interface modification of sensitized TiO2 surfaces by co-adsorbents on photovoltaic performance is detailed. We investigated different functional groups of co-adsorbents, such as carboxylic (4-guanidino butyric acid, chenodeoxycholic acid), phosphinic (dineohexyl phosphinic acid), and phosphonic (dodecyl phosphonic acid), to better highlight their influence on the device performance and accurately classify them into de-aggregating agents or agents with both de-aggregating and co-adsorbing properties. By optimizing the type of co-adsorbent and its concentration in the dye solution, we reached an efficiency of 11. Read More
The molecular structure at charged solid/liquid interfaces is vital for many chemical or electrochemical processes, such as adhesion, catalysis or the stability of colloidal dispersions. How cations influence structural hydration forces and interactions across negatively charged surfaces have been studied in great detail. However, how anions influence structural hydration forces on positively charged surfaces is much less understood. Read More
In this work we propose four non-coupled binding energies of intermediates as descriptors, or 'genes', for predicting the product distribution in CO2 electroreduction. Simple reactions can be understood by the Sabatier principle (catalytic activity vs. one descriptor), while more complex reactions tend to give multiple very different products and consequently the product selectivity is a more complex property to understand. Read More
Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland.
Room-temperature ionic liquids (RTILs) are promising new electrolytes for efficient carbon dioxide reduction. However, due to their high viscosity, the mass transport of CO2 in RTILs is typically slow, at least one order of magnitude slower than in aqueous systems. One possibility to improve mass transport in RTILs is to decrease their viscosity through dilution with water. Read More
Universitat de Girona, Institut de Quimica Computacional i Catalisi, Campus de Montilivi, 17071, Girona, SPAIN.
We propose a simple method of calculating the electron correlation energy density e_c(r) and the correlation potential V_c(r) from second-order Møller-Plesset amplitudes and its generalization for the case of a Configuration Interaction wavefunction, based on Nesbet's theorem. The correlation energy density obtained by this method for free and spherically confined Be and He atoms was employed to fit a local analytical density functional based on Wigner's functional. The functional is capable to reproduce a strong increase of the correlation energy with decreasing the confined radius for the Be atom. Read More
We present here new substrates for Surface Enhanced Raman Spectroscopy (SERS). The synthesis of colloidal nanoparticles through organometallic route allowed to obtain gold, silver or copper nanoparticles of well-controlled shapes and sizes (between 5 and 12 nm in diameter). The organization of these nanoparticles into large-scale 3D superlattices produces a very large number of "hot spots" at the origin of the signal enhancement. Read More
We demonstrate optical pumping lasers based on colloidal quantum dots, with a very thin geometry of ~ 20 nm thick film. Obstacles in ultra-small laser devices come from the limitation of gain materials and the size of cavities for lasing modes, which requires a minimum thickness of the gain media (typically greater than 50~100 nm). Here we introduce dielectric waveguide structures with a high refractive index, in order to reduce the thickness of quantum dot gain media as well as their threshold energy (~39% comparing to the original gain medium). Read More
University of Eastern Finland, Department of Chermistry, Yliopistokatu 7, 80100, Joensuu, FINLAND.
The structurally ill-characterized methylaluminoxane (MAO) is the activator of choice in olefin polymerization catalysis. We have carried out large scale and systematic quantum chemical calculations to simulate the thermodynamics of its formation by controlled hydrolysis of trimethylaluminum (TMA), extending the studies up to 25 Al atoms, and thus, for the first time, to the real size domain of MAO. In agreement with previous postulates on its structure, MAO is shown to favor cage-like structures, with common characteristics of containing associated TMA, regardless of size or shape. Read More
Herein, we present a theoretical study of systems with long-range Lewis acid-base interactions that involve a triel center and two electron donor species. These intermediate situations, between LB-AX3 and LB-AX3 -LB (LB=Lewis base, A=group 13 element), exist experimentally and their interaction topologies obey precise geometrical rules, such that they show a marked directionality and a clear dependence between the two A-LB distances. Despite the relatively long acid⋅⋅⋅base distances of up to 4 Å, the interaction energies calculated at the M06-2X/aug-cc-pVTZ level are considerably large (5-25 kcal mol(-1) ). Read More
Universite de Nice Sophia Antipolis, LPMC, UMR 7336, Parc Valrose, 06100, Nice, FRANCE.
A smart stimuli responsive surface is fabricated by the subsequent electro-copolymerization of pyrene monomers followed by a basic and acid treatment, respectively. Copolymers of fluorinated pyrenes and pyreneacetic acid were produced with different molar concentration of each monomer (0, 25, 50, 75 and 100% of Py-nF6 vs. Py-COOH) by an electrochemical process. Read More
Self-assembled DNA nanostructures hold great promises in the fields of nanofabrication, biosensing and nanomedicine. However, the inherent low stability of the DNA double helices formed by weak interaction largely hinders the assembly and functions of DNA nanostructure. In this study, we redesigned and constructed a 6-helix DNA bundle and a 6-helix DNA nanotube by incorporation of unnatural base pairs, 5-Me-isoC/isoG and A/2-thioT into the double helices. Read More
This article describes the main strategies to activate and convert carbon dioxide (CO2) into valuable chemicals over catalytic surfaces. Coherent elements such as common intermediates are identified in the different strategies and concisely discussed based on the reactivity of CO2 with the aim to understand the decisive factors for selective and efficient CO2 conversion. Read More
Universidad Nacional del Nordeste, Química, Avenida Libertad 5460, Dpto. Química, 3400, Corrientes, ARGENTINA.
High-level quantum chemical calculations have been performed to investigated the interactions C=Se∙∙∙Se=C. Bounded structures are found with binding energies between -4 and -7 kJ mol-1. The energy decomposition analysis shows that the dispersion is the more attractive term and in all cases save one, the electrostatic interaction is attractive despite every selenium atom has a positive -hole at the extension of the C=Se bond. Read More
Queen's University of Belfast, School of Chemistry and Chemical Engineering, David Keir Building, Stranmillis Road, BT9 5AG, Belfast, UNITED KINGDOM.
The use of 5-phenyltetrazole, a bioisostere of benzoic acid, as an anion source to prepare an ionic liquid is described for the first time. Tetrabutylphosphonium 5-phenyltetrazolate undergoes phase separation from water with lower critical solution temperature phase behavior, in contrast to completely water miscible tetrabutylphosphonium benzoate, and also exhibits strong complexation with water with both eutectic and peritectic behavior that has not previously been observed in ionic liquid + water systems. The anhydrous and trihydrate salts were isolated and characterised by single crystal X-ray diffraction. Read More
School of Physics, National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China.
A three-dimensional Bi2 MoO6 nanostrip architecture was synthesized by the hydrothermal method using sodium oleate as a surfactant. The generated Bi2 MoO6 nanostrips intercross with each other to form a unique network structure with a band gap of 2.92 eV, corresponding to visible-light wavelength. Read More
Quantum chemical calculations are described which rationalize the recent X-ray diffraction (XRD) structure at 2.25 Å of the Mn4 Ca water oxidising complex (WOC) of photosystem II (PSII) in the S3 intermediate state. The new S3 XRD structure shows remarkable similarity to earlier atomic resolution (1. Read More
Highly efficient perovskite solar cells have been characterized by current density-voltage measurements in the dark at varied scan rates. The results were compared to the solar cells without a hole-transporting layer to investigate the role of ultrathin hole transporting layers in solar cell function. The parameters of internal voltage, diode ideality factor, capacitive current, and capacitance were calculated from the current density-voltage response of the cells in the dark. Read More
The oxidation by H2O2 of the human phospholipid hydroperoxide glutathione peroxidase (GPx4), used as model peroxidase selenoenzyme, as well as of its cysteine (Cys) and tellurocysteine (Tec) mutants, is investigated in silico through a combined classic and quantum mechanics approach to assess the role of the different chalcogens. To perform this analysis, new parameters for selenocysteine (Sec) and tellurocysteine (Tec) were accurately derived for the AMBER ff14SB force field. The oxidation represents the initial step of the anti-oxidant activity of GPx, which catalyzes the reduction of H2O2 and organic hydroperoxides by glutathione (GSH). Read More
A metal-organic approach has been employed for the preparation of anisotropic CuO nanoparticles. These nanostructures have been characterized by transmission and high resolution transmission electron microscopy, field-emission scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The CuO nanoparticles have been deposited as gas-sensitive layers on miniaturized silicon devices. Read More
An important aspect of phosphorene, the novel two-dimensional semiconductor, is whether holes and electrons can both be doped in this material. Some reports found that only electrons can be preferentially doped into phosphorene. There are some theoretical calculations showing charge-transfer interaction with both tetrathiafulvalene (TTF) and tetracyanoethylene (TCNE). Read More
Nafion proton exchange membranes dehydrate when they are used in gas phase and high temperature applications, such as fuel cells and (photo)electrolysis. Retaining a high level of membrane hydration under such conditions can be achieved by using inorganic fillers, but was never demonstrated for thin films. In this work, several types of siliceous nanoparticles were incorporated for the first time into Nafion thin films. Read More
Lead halide perovskite solar cells with remarkable power conversion efficiency have attracted much attention in recent years. However, there still exist many problems with their use that are not completely understood, and further studies are needed. Herein, the hole-transport layer dependence of the photovoltaic performance of perovskite solar cells is investigated in detail. Read More
Direct conversion of CO2 into CO and O2 was carried out in a packed-bed dielectric barrier discharge (DBD) non-thermal plasma reactor at low temperatures and atmospheric pressure. The maximum CO2 conversion of 22.6% was achieved when BaTiO3 pellets were fully packed into the discharge gap. Read More
Endohedral metallofullerene M@C66 (M = rare earth metal) has a unique structure that violates the well known "isolated pentagon rule" in fullerene science. Although the synthesis of M@C66 has been achieved by using the arc-discharge method, the solvent extraction and purification of M@C66 remain challenges because of its radical character and extremely high reactivity. In this paper, we theoretically demonstrate the possibility of capturing this missing metallofullerene by exohedral functionalization of the C66 cage. Read More
The intermolecular binding between a Hamilton wedge and cyanuric acid, a frequently employed binding motif to achieve self-assembly of single-chain polymer nanoparticles, is studied by means of ab initio quantum-chemical and density functional theory calculations. A conformational analysis of the isolated compounds and the hydrogen-bonded complex reveals several low-energy structures, which are characterized based on their non-planarity and binding energy. New hypothetical binding motifs are proposed and proven to possess a superior binding energy, when becoming planar. Read More
Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.
Modulating the heterogeneous microenvironment in room-temperature ionic liquids (RTILs) by external stimuli is an important approach for understanding and designing external field-induced chemical reactions in natural and applied systems. Here, we report for the first time the redistribution of oxygen molecules related to microstructure changes in RTILs induced by an external laser field, which is probed simultaneously by the triplet-state dynamics of porphyrin. A remarkably long-lived triplet state of porphyrin is observed with changes of microstructures after irradiation, suggesting that charge-shifted O2 molecules are induced by the external field and/or rearranged intrinsic ions move from nonpolar domains into the polar domains of RTILs through electrostatic interactions. Read More
We utilize ion mobility mass spectrometry with an atmospheric pressure differential mobility analyzer coupled to a time-of-flight mass spectrometer (DMA-MS) to examine the formation of ion-vapor molecule complexes with seed ions of K(+) , Rb(+) , Cs(+) , Br(-) , and I(-) exposed to n-butanol and n-nonane vapor under subsaturated conditions. Ion-vapor molecule complex formation is indicated by a shift in the apparent mobility of each ion. Measurement results are compared to predicted mobility shifts based upon the Kelvin-Thomson equation, which is commonly used in predicting rates of ion-induced nucleation. Read More
The catalytic activities towards electrochemical CO2 reduction of two new rhenium and manganese complexes, namely fac-Mn(apbpy)(CO)3 Br (1) and fac-Re(apbpy)(CO)3 Cl (2) (apbpy=4-(4-aminophenyl)-2,2'-bipyridine), in both homogeneous and heterogeneous phases are compared. A glassy carbon electrode (GCE) surface has been functionalized with complexes 1 and 2 by two approaches: a) direct electrochemical oxidation of the amino group with formation of C-N bonds, and b) electrochemical reduction of the corresponding diazonium salts with formation of C-C bonds. The chemically modified GCEs show efficient conversion of CO2 into CO, with turnover numbers (TONs) about 60 times higher than those of the corresponding catalysts in homogeneous solutions, and in a much shorter time. Read More
Fixation of atmospheric nitrogen is central for the production of ammonia, which is the source of nitrogen fertilizers and is also emerging as a promising renewable fuel. While the development of efficient molecular-based artificial nitrogen fixation systems working under mild conditions is probably a Holy Grail, catalytic reduction of N2 by transition metal complexes is above all the main instrument to progress in mechanistic understanding of N2 splitting. In this minireview we first give an overview of molecular-based catalytic systems, including recent breakthroughs, and then we illustrate the alternative pathways for N2 reduction. Read More
Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON-UMR 5256, 2 Av. Albert Einstein, 69626, Villeurbanne, France.
Photoacoustic Fourier-transform infrared spectroscopy makes it possible to determine the organic composition of mixed-linker metal-organic frameworks. The sound produced upon IR irradiation enables the discrimination of azido and amino linkers in three different MOF platforms with a sensitivity that is two orders of magnitude higher than that achieved using classic IR analysis. Read More
We present an experimental electrophilicity index (ϻ) for the classification of radicals. The ϻ-scale is based on the equilibrium constant determined for the reversible addition of a radical R(.) to an aromatic radicophile (HisNH2 ). Read More
Banaras Hindu University, Department of Chemistry, UGC Centre of Advanced Study in Chemistry, 221005, Banaras, INDIA.
A diagonal suppressed F1 decoupled TOCSY experiment is developed for analyses of complex mixtures. In 2D homonuclear correlation, assignment of the cross peaks are crucial for structure elucidation. However, when cross peaks are close to the diagonal peaks in overcrowded spectral regions, their assignment becomes tedious. Read More