New Silver Tellurates – The Crystal Structures of a Third Modification of Ag2Te2O6 and of Ag4TeO5

Single crystals of a third modification of Ag₂Te₂O₆ (denoted as Ag₂Te₂O₆–III) and of Ag₄TeO₅ have been obtained as minor by‐products during hydrothermal phase formation experiments in the system Ag‐Hg‐Te‐O. The crystal structure of Ag₂Te₂O₆–III (P2₁/c, Z = 4, a = 6.4255(10), b = 6.9852(11), c = 13.204(2) Å, β = 90.090(3)°, 1885 independent reflections, R[F² > 2σ(F²)] = 0.0334, wR2(F² all) = 0.0817) comprises tellurium in oxidation states +IV and +VI and is topologically related to the structure of the Ag₂Te₂O₆–I modification, which consists of similar layers and interjacent layers of Ag⁺ cations. Ag₄TeO₅ (C2/c, Z = 8, a = 16.271(2), b = 6.0874(10), c = 11.4373(16) Å, β = 106.730(10)°, 2372 independent reflections, R[F² > 2σ(F²)] = 0.0288, wR2(F² all) = 0.0737) is made up of a layer‐like arrangement of isolated [Te^VI₂O₁₀] double octahedra and of Ag⁺ cations situated both in layers parallel and inside the layers of the anionic moieties.     

Synthetic Activators of Cell Migration Designed by Constructive Machine Learning

Constructive machine learning aims to create examples from its learned domain which are likely to exhibit similar properties. Here, a recurrent neural network was trained with the chemical structures of known cell-migration modulators. This machine learning model was used to generate new molecules that mimic the training compounds. Two top-scoring designs were synthesized, and tested for functional activity in a phenotypic spheroid cell migration assay. These computationally generated small molecules significantly increased the migration of medulloblastoma cells. The results further corroborate the applicability of constructive machine learning to the de novo design of druglike molecules with desired properties.     

Controlling spin-spin network dynamics by repeated projective measurements

We show that coupled-spin network manipulations can be made highly effective by repeated projections of the evolving quantum states onto diagonal density-matrix states (populations). As opposed to the intricately crafted pulse trains that are often used to fine-tune a complex network's evolution, the strategy hereby presented derives from the "quantum Zeno effect" and provides a highly robust route to guide the evolution by destroying all unwanted correlations (coherences). We exploit these effects by showing that a relaxationlike behavior is endowed to polarization transfers occurring within a N-spin coupled network. Experimental implementations yield coupling constant determinations for complex spin-coupling topologies, as demonstrated within the field of liquid-state nuclear magnetic resonance.     

New Rare‐Earth Metal Germanides RE2Ge9 (RE = Nd,Sm) by Thermal Decomposition of High‐Pressure Phases REGe5

The rare‐earth metal germanides RE₂Ge₉ (RE = Nd, Sm) have been prepared by thermal decomposition of the metastable high‐pressure phases REGe₅ at ambient pressure. The compounds adopt an orthorhombic unit cell with a = 396.34(4) pm; b = 954.05(8) pm and c = 1238.4(1) pm for Nd₂Ge₉ and a = 395.46(7) pm; b = 946.4(2) pm and c = 1232.1(3) pm for Sm₂Ge₉. Crystal structure refinements reveal space group Pmmn (No. 59) for Nd₂Ge₉. The atomic pattern resembles an ordered defect variety of the pentagermanide motif REGe₅ (RE = La; Nd, Sm, Gd, Tb) comprising corrugated germanium layers. These condense into a three‐dimensional network interconnected by eight‐coordinated germanium atoms. The resulting framework channels along [100] enclose the neodymium atoms. With respect to the atomic arrangement of the pentagermanides, half of the interlayer germanium atoms are eliminated in an ordered way so that occupied and empty germanium columns alternate along [001]. The rare‐earth metal atoms of both types of compounds, REGe₅ and RE₂Ge₉, exhibit the electronic states 4f ³ and 4f ⁵ (oxidation state +3) for neodymium and samarium, respectively, evidencing that the modification of the germanium network leaves the electron configuration of the metal atoms unaffected.     

Optimal dynamical decoherence control of a qubit

We present a theory of dynamical control by modulation for optimal decoherence reduction. The theory is based on the non-Markovian Euler-Lagrange equation for the energy-constrained field that minimizes the average dephasing rate of a qubit for any given dephasing spectrum.     

Similarities and Differences between Crystal and Enzyme Environmental Effects on the Electron Density of Drug Molecules

The crystal interaction density is generally assumed to be a suitable measure of the polarization of a low-molecular weight ligand inside an enzyme, but this approximation has seldomly been tested and has never been quantified before. In this study, we compare the crystal interaction density and the interaction electrostatic potential for a model compound of loxistatin acid (E64c) with those inside cathepsin B, in solution, and in vacuum. We apply QM/MM calculations and experimental quantum crystallography to show that the crystal interaction density is indeed very similar to the enzyme interaction density. Less than 0.1 e are shifted between these two environments in total. However, this difference has non-negligible consequences for derived properties.     

Intramolecular synergism,an explanation for the enhanced fungitoxicity of halo-8-quinolinols

Summary An antifungal study againstAspergillus niger,A. oryzae,Myrothecium verrucaria, andTrichoderma viride in Yeast Nitrogen Base supplemented with 1%D-glucose and 0.088%L-asparagine was carried out using 8-quinolinol and 3-, 5-, 6-, 7-, 3,6-, and 5,7-chlorinated and brominated-8-quinolinols. Binary mixtures of 3- and 6-halo- and 5- and 7-halo-8-quinolinols were intermolecularly synergistic. MICs of the monohalo synergistic mixtures admixed with a MIC of the corresponding dihalo-8-quinolinols were not synergistic. The dihalo-8-quinolinols with substituents in positions corresponding to those of the synergistic binary mixtures appeared to attack the same sites of action as the binary pairs. The enhanced activities of 3,6- and 5,7-dichloro-8-quinolinols and 3,6- and 5,7-dibromo-8-quinolinols are believed to be due to intramolecular synergism. The greater fungitoxicity of 5-, 6-, and 7-monohalo-8-quinolinols over 8-quinolinol can also be explained as due to intramolecular synergism. 3,6-Dihalo- and 5,7-dihalo-8-quinolinols formed synergistic pairs of compounds.

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Intramolekularer Synergismus als Erklärung für die erhöhte Fungitoxizität von halogenierten 8-Chinolinolen

Zusammenfassung 8-Chinolinol und verschiedene halogenierte 8-Chinolinole wurden auf ihre Fungitoxizität gegenüberAspergillus niger,A. oryzae,Myrothecium verrucaria undTrichoderma viride untersucht. Binäre Mischungen von 3- und 6-Halogen- bzw. 5- und 7-Halogen-8-chinolinol zeigten intermolekularen Synergismus, während bei Mischungen von mono- und dihalogenierten 8-Chinolinolen kein entsprechender Effekt beobachtet werden konnte. Die erhöhte Aktivität von 3,6-und 5,7-Dichlor-8-chinolinol und 3,6- und 5,7-Dibrom-8-chinolinol wird durch intramolekularen Synergismus erklärt, desgleichen die höhere Aktivität monohalogenierter 8-Chinolinole gegenüber 8-Chinolinol. 3,6-Dihalogenierte und 5,7-dihalogenierte 8-Chinolinole bilden synergistische Paare.