Prediction of heptagonal bipyramidal nonacoordination in highly viable [OB-M©B7O7-BO]− (M = Fe, Ru, Os) complexes

Non-spherical distributions of ligand atoms in coordination complexes are generally unfavorable due to higher repulsion than for spherical distributions. To the best of our knowledge, non-spherical heptagonal bipyramidal nonacoordination is hitherto unreported, because of extremely high repulsion among seven equatorial ligand atoms. Herein, we report the computational prediction of such nonacoordination, which is constructed by the synergetic coordination of an equatorial hepta-dentate centripetal ligand (B7O7) and two axial mono-dentate ligands (-BO) in the gear-like mono-anionic complexes [OB-M©B7O7-BO]– (M = Fe, Ru, Os). The high repulsion among seven equatorial ligand B atoms has been compensated by the strong B–O bonding. These complexes are the dynamically stable (up to 1500 K) global energy minima with the HOMO-LUMO gaps of 7.15 to 7.42 eV and first vertical detachment energies of 6.14 to 6.66 eV (being very high for anions), suggesting their high probability for experimental realization in both gas-phase and condensed phases. The high stability stems geometrically from the surrounded outer-shell oxygen atoms and electronically from meeting the 18e rule as well as possessing the σ + π + δ triple aromaticity. Remarkably, the ligand-metal interactions are governed not by the familiar donation and backdonation interactions, but by the electrostatic interactions and electron-sharing bonding.

Fundamental Investigation for Processing of Pb-Cu-S-Bearing Materials

The processing of polymetallic materials provides some challenges to every flowsheet. Within Aurubis Cu-Pb-metallurgical flowsheet, a broad range of raw materials and intermediates are processed. Continuous improvements are required to adapt the flowsheet according to the changing material quantity and quality. Therefore, thermodynamic modeling is the desired and most efficient way to conduct scenario analysis. Hence, databases and software are becoming better and better as the acceptance of this method increased. Further understanding is promoted by conducting experimental test work to validate the calculated results. In this research work, the impact of various oxygen potential on the formation of the condensed phases’ slag, matte, speiss and crude lead were investigated. A frequent check of slag metallurgy, in particular, the iron and lead concentration, provide feedback if the metallurgical process is operating at the right oxygen potential. Following, the calculated distribution coefficients for Cu, Pb, As, Sb, Sn and Ni between matte/speiss and speiss/lead are discussed.

Negative Thermal Quenching of Photoluminescence from Liquid-Crystalline Molecules in Condensed Phases

The luminescence of materials in condensed phases is affected by not only their molecular structures but also their aggregated structures. In this study, we designed new liquid-crystalline luminescent materials based on biphenylacetylene with a bulky trimethylsilyl terminal group and a flexible alkoxy chain. The luminescence properties of the prepared materials were evaluated, with a particular focus on the effects of phase transitions, which cause changes in the aggregated structures. The length of the flexible chain had no effect on the luminescence in solution. However, in crystals, the luminescence spectral shape depended on the chain length because varying the chain length altered the crystal structure. Interestingly, negative thermal quenching of the luminescence from these materials was observed in condensed phases, with the isotropic phase obtained at high temperatures exhibiting a considerable increase in luminescence intensity. This thermal enhancement of the luminescence suggests that the less- or nonemissive aggregates formed in crystals are dissociated in the isotropic phase. These findings can contribute toward the development of new material design concepts for useful luminescent materials at high temperatures.

Dynamical Component Exchange in a Model Phase Separating System: an NMR-based Approach

Biomolecular phase separation plays a key role in spatial organization of cellular activities. Dynamic formation and rapid component exchange between phase separated cellular bodies and their environment are crucial for their function. Here, we employ a well-established phase separating model system, namely, triethylamine (TEA)-water mixture, and develop an NMR approach to detect the exchange of scaffolding TEA molecules between separate phases and determine the underlying exchange rate. We further demonstrate how the advantageous NMR properties of fluorine nuclei provide access to otherwise inaccessible exchange processes of a client molecule. The developed NMR-based approach allows quantitative monitoring of the effect of regulatory factors on component exchange and facilitates “exchange”-based screening and optimization of small molecules against druggable biomolecular targets located inside condensed phases.

On the Many-Body Expansion of an Interaction Energy of Some Supramolecular Halogen-Containing Capsules

A tetramer model was investigated of a remarkably stable iodine-containing supramolecular capsule that was most recently characterized by other authors, who described emergent features of the capsule’s formation. In an attempt to address the surprising fact that no strong pair-wise interactions between any of the respective components were experimentally detected in condensed phases, the DFT (density-functional theory) computational model was used to decompose the total stabilization energy as a sum of two-, three- and four-body contributions. This model considers complexes formed between either iodine or bromine and the crucial D4h-symmetric form of octaaryl macrocyclic compound cyclo[8](1,3-(4,6-dimethyl)benzene that is surrounded by arenes of a suitable size, namely, either corannulene or coronene. A significant enthalpic gain associated with the formation of investigated tetramers was revealed. Furthermore, it is shown that the total stabilization of these complexes is dominated by binary interactions. Based on these findings, comments are made regarding the experimentally observed behavior of related multicomponent mixtures.

Synergistic effect of chitosan derivative and DOPO for simultaneous improvement of flame retardancy and mechanical property of epoxy resin

In this work, the effects of a chitosan-based derivative (CSA), DOPO and CSA-DOPO additives on the flammable properties of EP composites were systematically studied, where CSA was synthesized by a facile condensation between chitosan (CS) and 9-anthralaldehyde and. DOPO was 9, 10-dihydro-9-oxa-10- phosphaphenanthreene-10-oxide. The mass ratio of CS and 9-anthralaldehyde in CSA was determined by elemental analysis and theoretical calculation, which matched well with each other. Under the 8% addition in EP, EP/2.66%/5.34%DOPO sample was the only one, which passed the UL-94 rating and exhibited the highest LOI value of 36.4%. Compared with EP, the cone calorimeter test (CC) showed that the total smoke emission value and the peak heat release rate of the CSA and DOPO modified EP decreased 36.0% and 61.9%, respectively, and the residual char amount increased by 151%. The possible flame retardant mechanism of CSA/DOPO towards EP was proposed according to the results of the real time FTIR spectra at different pyrolysis temperatures, cone calorimeter and Py-GC/MS analysis for EP and EP/2.66%CSA/5.34%DOPO samples, and Raman spectra and XPS for their char residues. Moreover, the incorporation of CSA/DOPO effectively improved the mechanical properties, especially, the flexural strength was increased by 52.3%. It was proposed that CSA/DOPO plays roles in both vapor and condensed phases, and the synergistic effect of CSA and DOPO significantly improve the flame retardancy and mechanical strength of EP.