Large magnetodielectric coupling in the vicinity of metamagnetic transition in 6H−perovskite Ba3GdRu2O9

The 6H-perovskites Ba3RRu2O9 (R = rare earth element) demonstrate the magnetodielectric (MD) coupling as a manifestation of 4d - 4f magnetic interactions. Here, we have reported a detailed study of the structural, magnetic, heat capacity, and MD properties of the 6H-perovskite Ba3GdRu2O9. The signature of long-range antiferromagnetic (AFM) ordering at ~14.8 K (TN) is evident from the magnetization and heat capacity studies. The TN shifts towards the lower temperature side, apart from splitting in two with the application of the magnetic field. Field-dependent magnetization at 2 K shows three metamagnetic transitions with the opening of small hysteresis in different regions. A new transition at T1 emerges after the onset of the first metamagnetic transition. Complex magnetic behavior is observed in different magnetic field regions whereas these field regions themselves vary with the temperature. Dielectric response recorded at zero and 80 kOe field exhibits the development of MD coupling well above TN. The MD coupling (~ 4.5 % at 10 K) is enhanced by 25 % as compared to the Dy counterpart. Effect of complex magnetic behavior is also conveyed in the MD results where the maximum value of MD coupling is observed in the vicinity of 10 K (onset of T1) and near the second metamagnetic transition. Our investigation suggests that both Gd and Ru moments align simultaneously at TN. Short-range magnetic correlations are possibly responsible for MD coupling above TN.

Dielectric switching, SHG response and Pd(ii) adsorption of a multifunctional phase-transition complex

One-dimensional coordination polymer [(C2H4OH)C4H9NS]CdCl3 has the performance of dielectric switching and SHG response. And the compound can adsorb precious Pd(ii) and the adsorption could be monitored by dielectric anomaly and SHG signal.

Thermodynamics of the DNA Repair Process by Endonuclease VIII

In the present work, a thermodynamic analysis of the interaction between endonuclease VIII (Endo VIII) and model DNA substrates containing damaged nucleotides, such as 5,6-dihydrouridine and 2-hydroxymethyl-3-hydroxytetrahydrofuran (F-site), was performed. The changes in the fluorescence intensity of the 1,3-diaza-2-oxophenoxazine (tCO) residue located in the complementary chain opposite to the specific site were recorded in the course of the enzyme-substrate interaction. The kinetics was analyzed by the stopped-flow method at different temperatures. The changes of standard Gibbs free energy, enthalpy, and entropy of sequential steps of DNA substrate binding, as well as activation enthalpy and entropy for the transition complex formation of the catalytic stage, were calculated. The comparison of the kinetic and thermodynamic data characterizing the conformational transitions of enzyme and DNA in the course of their interaction made it possible to specify the nature of the molecular processes occurring at the stages of substrate binding, recognition of the damaged base, and its removal from DNA.

Pressure-induced switching properties of the iron(iii) spin-transition complex [FeIII(3-OMeSalEen)2]PF6

The volume-dependent properties of a spin-crossover Fe(iii) prototypical compound revealed by combined magnetic, vibrational and structural investigations of the pressure effect.

Unexpected fragmentation of bis(triarylstannanethiocarbonyl)disulfides, formation and X-ray structure of triarylstannyl triarylstannanecarbodithioates

The synthesis of bis(triarylstannanethiocarbonyl)disulfides was attempted by oxidation of lithium triaryl stannane carbodithioates with molecular iodine. Unexpectedly, the desired compounds are highly unstable and undergo subsequent fragmentation giving triarylstannyl triarylstannanecarbodithioates. The proposed mechanism for this transformation assumes intramolecular nucleophilic substitution with formation of six-membered ring transition complex, stabilized by interaction between tin and thiocarbonyl sulfur atom. Obtained compounds were identified by mass-spectrometry and NMR spectroscopies, and their structures were analyzed by X-ray diffraction. These molecules show the existence of intramolecular non-bonding interactions between the sulfur atoms of the thiocarbonyl moieties and tin atoms. These interactions reflect the tin - sulfur affinity and are the main driving force in the fragmen tation of bis(triphenylstannanethiocarbonyl)disulfides.