Too fast and too furious: thermoanalytical and quantum chemical study of the thermal stability of 4,4'-dinitro-3,3'-diazenofuroxan.

Novel energetic materials (EM) often combine two intrinsically counter trends, , a high energy density and mediocre safety parameters, like thermal stability and sensitivity toward mechanical stimuli. A rational design of promising EMs requires a proper understanding of their thermal stability at both macroscopic and molecular levels. In the present contribution, we studied in detail the thermal stability of 4,4'-dinitro-3,3'-diazenofuroxan (DDF), an ultrahigh-performance energetic material with a reliable experimental detonation velocity being very close to 10 km s.

A comprehensive guide for accurate conformational energies of microsolvated Li clusters with organic carbonates.

Organic carbonates and their mixtures are frequently used in electrolyte solutions in lithium-ion batteries. Rationalization and tuning of the related Li solvation processes are rooted in the proper identification of the representative low-energy spatial structures of the microsolvated Li(S) clusters. In this study, we introduce an automatically generated database of conformational energies (CEs), LICARBCONF806, comprising 806 diverse conformers of Li clusters with 7 common organic carbonates.

Extended investigation of the conductive characteristics of monoclinic tungstates with a BiWO ( = La, Pr or Nd) composition.

δ-BiO-based materials have long been a focus of interest as potential solid oxide fuel cell materials due to their high electrical conductivity. Here, extensive studies of thermal stability, polymorphism and conductivity have been carried out for the first time on BiWO ( = La, Pr or Nd) compounds in the ternary BiO-O-WO system, mentioned more than 20 years ago by Watanabe. The obtained single-phase materials were found to be sufficiently dense (more than 94%) and thermally stable (up to 900 °C).

An influence of electronic structure theory method, thermodynamic and implicit solvation corrections on the organic carbonates conformational and binding energies.

An impact of an electronic structure or force field method, gas-phase thermodynamic correction, and continuum solvation model on organic carbonate clusters (S) conformational and binding energies is explored. None of the tested force field (GFN-FF, GAFF, MMFF94) and standard semiempirical methods (PM3, AM1, RM1, PM6, PM6-D3, PM6-D3H4, PM7) can reproduce reference RI-SCS-MP2 conformational energies. Tight-binding GFNn-xTB methods provide more realistic conformational energies which are accurate enough to discard the least stable conformers.

Understanding the Electric Double Layer at the Electrode-Electrolyte Interface: Part I - No Ion Specific Adsorption.

In this work, we present a mean-field model that takes into account the key components of electrical double layer theory at the interface between an electrode and an electrolyte solution. The model considers short-range specific interactions between different species, including electrode-ion repulsion, the hydration of ions, dielectric saturation of solvent (water), and excluded volume (steric) interactions between species. By solving a modified Poisson-Boltzmann equation, which is derived from the grand thermodynamic potential of an inhomogeneous electrolyte solution, and using the appropriate results of quantum chemistry calculations on the hydration of ions, we can accurately approximate the differential capacitance profiles of aqueous electrolyte solutions at the boundary with a silver electrode.

The Perfluoro-o-phenylene-mercury Trimer [Hg(o-CF)] - a Textbook Example of Phase-Dependent Structural Differences.

The geometric and electronic structure of [Hg(o-CF)] (1) in the gas phase, i. e. free of intermolecular interactions, was determined by a synchronous gas-phase electron diffraction/mass spectrometry experiment (GED/MS), complemented by quantum chemical calculations.

Ni, Cu, Zn, Pd, Ag and Cd Tetraphenylporphyrin Ab Initio Thermochemistry: Enthalpy of Formation of ZnTPP Revisited.

Groups 10-12 metalloporphyrins have been recognized for their numerous properties essential for the development of new sensing materials. In this work, accurate gas-phase enthalpies of formation, Δ(g,298.15), are predicted for the series of Ni, Cu, Zn, Pd, Ag, and Cd tetraphenylporphyrins (MTPPs) on the basis of the reaction-based Feller-Peterson-Dixon approach and high-level ab initio DLPNO-CCSD(T) calculations.

Extensive research of conductivity in the fluorite-like KLnMoOF (Ln = La, Pr, Nd) rare earth molybdates: theoretical and experimental data.

The conductive properties of fluorite-like structures KLnMoOF (Ln = La, Pr, Nd: KLM, KPM, KNM) have been studied theoretically and experimentally. Theoretical studies included the geometrical-topological analysis of voids and channels available for migration of working ions; bond valence site energy calculations of the oxygen ions' migration energy; quantum-chemical calculations for the estimation of the oxygen vacancies formation energy. Experimental measurements of conductivity were made using impedance spectroscopy and as a function of oxygen partial pressure.

New Mechanistic Insights into the Primary Thermolysis Reactions of 1,3,4,6-Tetranitrooctahydroimidazo-[4,5-]imidazole (BCHMX) from Predictive Local Coupled Cluster Calculations.

Theoretical studies of the decomposition mechanism of energetic materials quite often scrutinize only the primary thermolysis reactions. However, the secondary reactions are crucial, inter alia, for proper building of the combustion models and understanding the autocatalytic processes. In the present study, we applied predictive DLPNO-CCSD(T) calculations to elucidate the kinetics and decomposition mechanism of a novel promising energetic material, 1,3,4,6-tetranitrooctahydroimidazo [4,5-] imidazole (BCHMX).

High-Power-Density Thermoelectrochemical Cell Based on Ni/NiO Nanostructured Microsphere Electrodes with Alkaline Electrolyte.

Effective low-grade waste heat harvesting and its conversion into electric energy by the means of thermoelectrochemical cells (TECs) are a strong theme in the field of renewable energy investigation. Despite considerable scientific research, TECs have not yet been practically applied due to the high cost of electrode materials and low effectiveness levels. A large hypothetical Seebeck coefficient allow the harvest of the low-grade waste heat and, particularly, to use TECs for collecting human body heat.

Triggering gel-sol transition by weak magnetic field.

The self-assembly of small and always chiral molecules into fiber-like structures is a mysterious process, as the physics underlying such self-assembly is unclear. The energy necessary for this process exceeds the one provided by common dispersion interactions and hydrogen bonding. The recent results obtained by the scientific group of Prof.

Solv: An Alternative Continuum Model Implementation Based on Fixed Atomic Charges, Scaled Particle Theory, and the Atom-Atom Potential Method.

An alternative continuum model implementation is reported. The electrostatic contribution to the solvation Gibbs free energy utilizes the noniterative conductor-like screening model of Vyboishchikov and Voityuk (DOI: 10.1002/jcc.

First Iridium(IV) Chloride-Dimethyl Sulfoxide Complex [H(dmso)][IrCl(dmso-κO)]: Synthesis and Structure along with Novel Polymorph Modifications of [H(dmso)][-IrCl(dmso-κS)] and [H(dmso)][IrCl(dmso-κS)].

As evidenced by UV-Vis and EPR spectroscopies, the reaction of HIrCl·6HO or Na[IrCl]·HO with DMSO results in a slow reduction of Ir(IV) avoiding the formation of Ir(IV) dimethyl sulfoxide complexes in measurable quantities. More specifically, we successfully isolated and solved the crystal structure of a sodium hexachloridoiridate(III), Na[IrCl]·2HO, as a product of Na[IrCl]·HO reduction in an acetone solution. Furthermore, it was shown that [IrCl(MeCO)] species is gradually formed in an acetone solution of HIrCl·6HO upon storage.

Synthesis, Characterization, and Properties of High-Energy Fillers Derived from Nitroisobutylglycerol.

Herein we report a comprehensive laboratory synthesis of a series of energetic azidonitrate derivatives (ANDP, SMX, AMDNNM, NIBTN, NPN, 2-nitro-1,3-dinitro-oxypropane) starting from the readily available nitroisobutylglycerol. This simple protocol allows obtaining the high-energy additives from the available precursor in yields higher than those reported using safe and simple operations not presented in previous works. A detailed characterization of the physical, chemical, and energetic properties including impact sensitivity and thermal behavior of these species was performed for the systematic evaluation and comparison of the corresponding class of energetic compounds.

Changes in Structural and Thermodynamic Properties of Starch during Potato Tuber Dormancy.

The main reserve polysaccharide of plants-starch-is undoubtedly important for humans. One of the main sources of starch is the potato tuber, which is able to preserve starch for a long time during the so-called dormancy period. However, accumulated data show that this dormancy is only relative, which raises the question of the possibility of some kind of starch restructuring during dormancy periods.

Gas-phase thermochemistry of noncovalent ligand-alkali metal ion clusters: An impact of low frequencies.

The experimental gas-phase thermochemistry of reactions: M (S)  + S → M (S) and M + nS→ M (S) , where M is an alkali metal and S is acetonitrile/ammonia, is reproduced. Three approximations are tested: (1) scaled rigid-rotor-harmonic-oscillator (sRRHO); (2) the sRRHO(100) identical to (1), but with all vibrational frequencies smaller than 100 cm replaced with 100 cm ; (3) Grimme's modified scaled RRHO (msRRHO) (Grimme, Chem. Eur.

Iron(II) Complexes with Porphyrin and Tetrabenzoporphyrin: CASSCF/MCQDPT2 Study of the Electronic Structures and UV-Vis Spectra by sTD-DFT.

The geometry and electronic structures of iron(II) complexes with porphyrin () and tetrabenzoporphyrin () in ground and low-lying excited electronic states are determined by DFT (PBE0/def2-TZVP) calculations and the complete active space self-consistent field (CASSCF) method, followed by the multiconfigurational quasi-degenerate second-order perturbation theory (MCQDPT2) approach to determine the dynamic electron correlation. The minima on the potential energy surfaces (PESs) of the ground (A) and low-lying, high-spin (A) electronic states correspond to the planar structures of and with symmetry. According to the results of the MCQDPT2 calculations, the wave functions of the A and A electronic states are single determinant.

Accurate single crystal and gas-phase molecular structures of acenaphthene: a starting point in the search for the longest C-C bond.

The molecular structure of acenaphthene has been determined experimentally in the gas phase using gas electron diffraction intensities and literature-available rotational constants. Supplementary high-level quantum-chemical calculations were utilized in refinements of the semi-empirical equilibrium structure. In this work we investigate on how different schemes of GED data averaging and weighting can be used for obtaining the most accurate and precise structural parameters.

Excessive α-β Oscillations Mark Enlarged Motor Sign Severity and Parkinson's Disease Duration.

Background: β Oscillations in the subthalamic nucleus (STN) have been proven to contribute to Parkinson's disease (PD), but the exact borders of β subbands vary substantially across the studies, and information regarding heterogeneity of β rhythmic activity is still limited. Recently, α oscillations in the basal ganglia have also become the focus of PD research.

Objectives: The aim was to study rhythmic oscillations in the STN in PD patients to identify different subbands with stable oscillatory peaks within a broad α-β range and to establish their associations with motor symptoms.

Thermochemistry, Tautomerism, and Thermal Stability of 5,7-Dinitrobenzotriazoles.

Nitro derivatives of benzotriazoles are safe energetic materials with remarkable thermal stability. In the present study, we report on the kinetics and mechanism of thermal decomposition for 5,7-dinitrobenzotriazole () and 4-amino-5,7-dinitrobenzotriazole (). The pressure differential scanning calorimetry was employed to study the decomposition kinetics of experimentally because the measurements under atmospheric pressure are disturbed by competing evaporation.

Anti-cancer activity of ultra-short single-stranded polydeoxyribonucleotides.

One of the features that differentiate cancer cells is their increased proliferation rate, which creates an opportunity for general anti-tumor therapy directed against the elevated activity of replicative apparatus in tumor cells. Besides DNA synthesis, successful genome replication requires the reparation of the newly synthesized DNA. Malfunctions in reparation can cause fatal injuries in the genome and cell death.

Physical and numerical aspects of sodium ion solvation free energies the cluster-continuum model.

Sodium cation solvation Gibbs free energies (Δ(Na)) have been obtained in water, dimethylformamide, dimethyl sulfoxide, ethanol, acetone, acetonitrile, and methanol through the "monomer cycle" cluster-continuum approach where a solvent reference state is described by infinitely separated molecules. The following steps are vital for obtaining reliable Δ(Na) values: (a) a meticulous conformational search involving dispersion corrected density functional theory (DFT-D) and the continuum solvation model (CSM); (b) gas-phase DFT-D geometry optimization followed by single-point (SP) domain-based local pair natural orbital coupled clusters including single, double, and partly triple excitation (DLPNO-CCSD(T)) calculations in conjunction with the complete basis set extrapolation; (c) advanced statistical thermodynamic treatment of the low harmonic frequencies (<100 cm) to obtain the robust gas-phase Gibbs free energy correction; (d) gas-phase and dielectric continuum SP with non-electrostatic contributions included in the CSM; (e) an evaluation of the relative thermodynamic stability of the Na(S) clusters to identify the number of explicit solvent molecules to be considered. Our refined computational protocol is promising with a Pearson correlation coefficient between the predicted and experimental data, , of 0.

Gas-phase equilibrium molecular structures and thermochemistry of anthracene and rubrene.

Semi-experimental gas-phase structures of anthracene and rubrene (5,6,11,12-tetraphenyltetracene) were determined by means of gas electron diffraction (GED). The use of the flexible restraints in the refinement of the GED data successfully resolves non-equivalent C-C bond lengths. The tetracene core of an isolated rubrene molecule was found to exhibit a twist distortion of about 18°; this is less than DFT calculations predict (30-40°).

Kinetic Model of Diclofenac Degradation Developed Using Multivariate Curve Resolution Method.

This study presents the kinetic modeling of the natural long-term aging of the pharmaceutical substance as well as the intact tablets of Diclofenac. Datasets are collections of near-infrared spectra acquired from the intact tablets packed in plastic blisters and the spectra of the pure substance. Fresh samples and samples at different stages of degradation are analyzed.