Functionalized Amorphous Carbon Materials via Reactive Molecular Dynamics Simulations.

We derive a database of atomistic structural models of amorphous carbon materials endowed with exohedral functional groups. We start from phases previously derived using the DynReaxMas method for reactive molecular dynamics simulations, which exhibit atomistic and medium-length-scale features in excellent agreement with available experimental data. Given a generic input structure/phase, we develop postprocessing simulation algorithms mimicking experimental preparation protocols aimed at: (1) "curing" the phase to decrease the defect concentration; (2) automatically selecting the most reactive carbon atoms via interaction with a probe molecular species, and (3) stabilizing the phase by saturating the valence of carbon atoms with single-bond functional groups.

A robust Fe-based heterogeneous photocatalyst for the visible-light-mediated selective reduction of an impure CO stream.

The transformation of CO into value-added products from an impure CO stream, such as flue gas or exhaust gas, directly contributes to the principle of carbon capture and utilization (CCU). Thus, we have developed a robust iron-based heterogeneous photocatalyst that can convert the exhaust gas from the car into CO with an exceptional production rate of 145 μmol g h. We characterized this photocatalyst by PXRD, XPS, ssNMR, EXAFS, XANES, HR-TEM, and further provided mechanistic experiments, and multi-scale/level computational studies.

Disclosing gate-opening/closing events inside a flexible metal-organic framework loaded with CO by reactive and essential dynamics.

We have combined reactive molecular dynamics simulations with principal component analysis to provide a clearer view of the interactions and motion of the CO molecules inside a metal-organic framework and the movements of the MOF components that regulate storage, adsorption, and diffusion of the guest species. The tens-of-nanometer size of the simulated model, the capability of the reactive force field tuned to reproduce the inorganic-organic material confidently, and the unconventional use of essential dynamics have effectively disclosed the gate-opening/closing phenomenon, possible coordinations of CO at the metal centers, all the diffusion steps inside the MOF channels, the primary motions of the linkers, and the effects of their concerted rearrangements on local CO relocations.

An Atomically Dispersed Mn-Photocatalyst for Generating Hydrogen Peroxide from Seawater via the Water Oxidation Reaction (WOR).

In this work, we have fabricated an aryl amino-substituted graphitic carbon nitride (g-CN) catalyst with atomically dispersed Mn capable of generating hydrogen peroxide (HO) directly from seawater. This new catalyst exhibited excellent reactivity, obtaining up to 2230 μM HO in 7 h from alkaline water and up to 1800 μM from seawater under identical conditions. More importantly, the catalyst was quickly recovered for subsequent reuse without appreciable loss in performance.

Stability and potential degradation of the α',β'-epoxyketone pharmacophore on ZnO nanocarriers: insights from reactive molecular dynamics and density functional theory calculations.

We investigate the structure and dynamics of a zinc oxide nanocarrier loaded with Carfilzomib, an epoxyketone proteasome inhibitor developed for treating multiple myeloma. We demonstrate that, even though both bare and functionalized zinc oxide supports have been used for drug delivery, their interactions with the reactive functional groups of the ligands could be detrimental. This is because pharmacophores like α',β'-epoxyketones should preserve the groups required for the drug activity and be capable of leaving the vehicle at the target site.

Role of the redox state of cerium oxide on glycine adsorption: an experimental and theoretical study.

The role of the oxidation state of cerium cations in a thin oxide film in the adsorption, geometry, and thermal stability of glycine molecules was studied. The experimental study was performed for a submonolayer molecular coverage deposited in vacuum on CeO(111)/Cu(111) and CeO(111)/Cu(111) films by photoelectron and soft X-ray absorption spectroscopies and supported by calculations for prediction of the adsorbate geometries, C 1s and N 1s core binding energies of glycine, and some possible products of the thermal decomposition. The molecules adsorbed on the oxide surfaces at 25 °C in the anionic form the carboxylate oxygen atoms bound to cerium cations.

Π-Π Stacking Complex Induces Three-Component Coupling Reactions To Synthesize Functionalized Amines.

π-π stacking and ion-pairing interactions induced the generation of α-amino radicals under the irradiation of visible light without the requirement of an expensive photocatalyst. This strategy enabled the construction of functionalized amines via three-component coupling reactions with broad scope (we report >50 examples with an up to 90 % yield). This synthetic pathway also delivered complex functionalized amines with a very high yield.

Molecularly Imprinted Nanoparticles towards MMP9 for Controlling Cardiac ECM after Myocardial Infarction: A Predictive Experimental-Computational Chemistry Investigation.

The recent advances in nanotechnology are revolutionizing preventive and therapeutic approaches to treating cardiovascular diseases. Controlling the extracellular matrix metalloproteinase (MMP) activation and expression in the failing human left ventricular myocardium represents a significant therapeutic target for heart disease. In this study, we used molecularly imprinting polymers (MIPs) to restore the correct balance between MMPs and their tissue inhibitors (TIMPs), and explored the potential of this technique exhaustively through chemical synthesis, physicochemical and biological characterizations, and computational chemistry methods.

Exploring the mechanisms of drug-delivery by decorated ZnO nanoparticles through predictive ReaxFF molecular dynamics simulations.

Herein, we study the assembling of a drug delivery nanocarrier through reactive molecular dynamics simulations based on an appropriately tuned force field. First, we focus on the combination of the various components (all selected in agreement with experiments), namely nanoparticle (ZnO), functional chains (oleic acid), drug (carfilzomib), and solvent molecules (ethanol), and then on the ability of the assembled nanotool to release its cargo in a physiological environment (water). The simulation results reveal that reactivity is crucial for characterizing the stability of the functionalized ZnONP, its dynamics, and its interactions with lipid chains and drug molecules.

Lignin-Supported Heterogeneous Photocatalyst for the Direct Generation of HO from Seawater.

The development of smart and sustainable photocatalysts is in high priority for the synthesis of HO because the global demand for HO is sharply rising. Currently, the global market share for HO is around 4 billion US$ and is expected to grow by about 5.2 billion US$ by 2026.

An augmented (multi-descriptor) grouping algorithm to optimize chemical ordering in nanoalloys.

We propose the Augmented Grouping Approach (AugGA) and its deployment in the Augmented Grouping GO (AugGGO) scheme, for an efficient exploration of the chemical ordering (or compositional structure) of multi-component (alloyed) nanoparticles. The approach is based on a 'grouping' strategy (previously proposed for high-symmetry structures) by which the number of compositional degrees of freedom of the system is decreased by defining sets of atoms (groups, or orbits, or shells) that are constrained to be populated by the same element. Three fundamental advances are here included with respect to previous proposals: (i) groups are defined on the basis of descriptors (no point-group symmetry is assumed), (ii) bulk groups can exploit general chemical ordering patterns taken from databases, and (iii) sub-grouping is realized a multi-descriptor strategy (here using two basic descriptors: the atomic energy and a few types of geometry patterns).

Structural Refinement of Carbimazole by NMR Crystallography.

The characterization of the three-dimensional structure of solids is of major importance, especially in the pharmaceutical field. In the present work, NMR crystallography methods are applied with the aim to refine the crystal structure of carbimazole, an active pharmaceutical ingredient used for the treatment of hyperthyroidism and Grave's disease. Starting from previously reported X-ray diffraction data, two refined structures were obtained by geometry optimization methods.

Correction: 2D oxides on metal materials: concepts, status, and perspectives.

Correction for '2D oxides on metal materials: concepts, status, and perspectives' by Giovanni Barcaro et al., Phys. Chem.

Diverse Phases of Carbonaceous Materials from Stochastic Simulations.

Amorphous carbon systems are emerging to have unparalleled properties at multiple length scales, making them the preferred choice for creating advanced materials in many sectors, but the lack of long-range order makes it difficult to establish structure/property relationships. We propose an original computational approach to predict the morphology of carbonaceous materials for arbitrary densities that we apply here to graphitic phases at low densities from 1.15 to 0.

New Mechanistic Insights into the Lignin β-O-4 Linkage Acidolysis with Ethylene Glycol Stabilization Aided by Multilevel Computational Chemistry.

Acidolysis in conjunction with stabilization of reactive intermediates has emerged as one of the most powerful methods of lignin depolymerization that leads to high aromatic monomer yields. In particular, stabilization of reactive aldehydes using ethylene glycol results in the selective formation of the corresponding cyclic acetals (1,3-dioxolane derivatives) from model compounds, lignin, and even from softwood lignocellulose. Given the high practical utility of this method for future biorefineries, a deeper understanding of the method is desired.

Modeling generation and growth of iron oxide nanoparticles from representative precursors through ReaxFF molecular dynamics.

Detailed dynamical characterization of the mechanisms responsible for the formation and growth of iron oxide nanoparticles remains a significant challenge not only for experimental techniques but also for theoretical methodologies due to the nanoparticle size, long simulation times, and complexity of the environments. In this work, we have designed a fast computational protocol based on atomistic reactive molecular dynamics, which is capable of simulating the whole synthetic and proliferation process of the nanoparticles (greater than 10 nm) in a homogeneous medium from organometallic precursors. We have defined appropriate growth accelerating strategies based on the observed reactions, which consisted of the formation of Fe-O-Fe bridges, linking separate precursors, and Fe˙ and FeO˙ radicals.

Phosphorene and Black Phosphorus: The P NMR View.

This work aims at characterizing for the first time the P spin interactions determining the nuclear magnetic resonance (NMR) properties of solid black phosphorus (bP) and of its few-layer exfoliated form (fl-bP). Indeed, the knowledge of these properties is still very poor, despite the great interest received by this layered phosphorus allotrope and its exfoliated 2D form, phosphorene. By combining density functional theory (DFT) calculations and solid-state NMR experiments on suspensions of fl-bP nanoflakes and on solid bP, it has been possible to characterize the P homonuclear dipolar and chemical shift interactions, identifying the network of P nuclei more strongly dipolarly coupled and highlighting two kinds of magnetically nonequivalent P nuclei.

2D oxides on metal materials: concepts, status, and perspectives.

Oxide materials at the two-dimensional limit, in particular in the form of ultrathin films of oxides (UTOx) grown on metal surfaces, represent promising materials in view of both fundamental science and technological applications. While the former aspect is widely recognized, these systems have not yet realized their full potential in terms of the latter (technological) aspect. In the present perspective, we review the field and its basic underlying concepts, and at the same time we provide an overview of the most promising future directions with a focus on their potential toward and relationships with real-world exploitation.

Experimental and theoretical elucidation of catalytic pathways in TiO-initiated prebiotic polymerization.

The tendency of glycine to form polymer chains on a rutile(110) surface under wet/dry conditions (dry-wet cycles at high temperature) is studied through a conjunction of surface sensitive experimental techniques and sequential periodic multilevel calculations that mimics the experimental procedures with models of decreasing complexity and increasing accuracy. X-ray photoemission spectroscopy (XPS) and thermal desorption spectroscopy (TDS) experimentally confirmed that the dry-wet cycles lead to Gly polymerization on the oxide support. This was supported by all the theoretical characterizations.

Modeling Nucleation and Growth of ZnO Nanoparticles in a Low Temperature Plasma by Reactive Dynamics.

The very first stages of nucleation and growth of ZnO nanoparticles in a plasma reactor are studied by means of a multiscale computational paradigm where the DFT-GGA approach is used to evaluate structure and electronic energy of small (ZnO) clusters ( N ≤ 24) that are employed as a training set (TS) for the optimization of a Reactive Force Field (ReaxFF). Reactive Molecular Dynamics (RMD) simulations based on this tuned ReaxFF are carried out to reproduce nucleation and growth in a realistic environment. Inside the reaction chamber the temperature is around 1200 K, and the zinc atoms are oxidized in an oxygen-rich atmosphere at high pressure (about 20 atm), whereas in the quenching chamber where the temperature is lower (about 800 K) the ZnO embryo-nanoclusters are grown.

Molecular dynamics simulations of melting and sintering of Si nanoparticles: a comparison of different force fields and computational models.

Melting and sintering of silicon nanoparticles are investigated by means of classical molecular dynamics simulations to disclose the dependence of modelling on the system type, the simulation procedure and interaction potential. The capability of our parametrization of a reactive force field ReaxFF to describe such processes is assessed through a comparison with formally simpler Stillinger-Weber and Tersoff potentials, which are frequently used for simulating silicon-based materials. A substantial dependence of both the predicted melting point and its variation as a function of the nanoparticle size on the simulation model is also highlighted.

Bimetallic Ag-Pt Sub-nanometer Supported Clusters as Highly Efficient and Robust Oxidation Catalysts.

A combined experimental and theoretical investigation of Ag-Pt sub-nanometer clusters as heterogeneous catalysts in the CO→CO reaction (COox) is presented. Ag Pt and Ag Pt clusters are size-selected in the gas phase, deposited on an ultrathin amorphous alumina support, and tested as catalysts experimentally under realistic conditions and by first-principles simulations at realistic coverage. In situ GISAXS/TPRx demonstrates that the clusters do not sinter or deactivate even after prolonged exposure to reactants at high temperature, and present comparable, extremely high COox catalytic efficiency.

Parametrization of a Reactive Force Field (ReaxFF) for Molecular Dynamics Simulations of Si Nanoparticles.

A novel computational approach, based on classical reactive molecular dynamics simulations (RMD) and quantum chemistry (QC) global energy optimizations, is proposed for modeling large Si nanoparticles. The force field parameters, which can describe bond breaking and formation, are derived by reproducing energetic and structural properties of a set of Si clusters increasing in size. These reference models are obtained through a new protocol based on a joint high temperature RMD/low temperature Basin Hopping QC search.