Visible light induced reversible extrusion of nitric oxide from a ruthenium(II) nitrosyl complex: a facile delivery of nitric oxide

The new ruthenium compound [Ru(NO)(pysiS4)]Br (3) (pysiS4 = 2,6-bis(3-triphenylsilyl-2-sulfanylphenylthiomethyl)pyridine), containing sterically bulky SiPh3 groups ortho to the thiolate donors, has been synthesized. In solution, 3 releases NO efficiently on exposure to visible light (lambda >/= 455 nm) at room temperature to afford [Ru(Br)(pysiS4)] (4). Treatment of 4 with NO yielded exclusively 3 without any metal-bound side reaction.     

Atom Economy and Yield of Synthesis Sequences

Atom economy (AE) or atom utilization was one of the first defining terms in the sustainable chemistry movement. In contrast to the often‐cited twelve (qualitative) principles of green chemistry, AE represents a metric for quantification purposes. The theoretical efficiency of a reaction expressed by its stoichiometric equation can be determined by AE=Product [g/mol]/(Substrate 1+Substrate 2+…?) [g/mol] and compared with synthetic alternatives. Of course, the atom economy will be of limited use, if starting materials differ much in complexity, i.e., in the degree of refinement. In these cases, their syntheses have to be taken in consideration, too. But, the further the retrospect goes and the more preceding synthesis steps ramify, the more complex the calculation gets. To overcome this limitation, we introduce a stepwise approach that is enabled by a simple modification of the above formula (P=product; S=substrate; Syn.=synthesis): AE=P [g/mol]/((S1/AE(Syn. of S1))+(S2/AE(Syn. of S2))+…?) [g/mol]. To illustrate this equation, which is derived mathematically, the convergent multistep synthesis of the natural product trans‐chrysanthemic acid is subjected to a stepwise method of calculation. The equation can be understood as a general expression for related ratios, i.e., there are corresponding modified equations for yield, selectivity, etc. In terms of the yield, it is no longer necessary to decide between the chains of the convergent synthesis, when possibly forced to ignore significant parts of the sequence. For demonstration purposes, the yield of the convergent synthesis of the natural product peridinin has been determined with a correspondingly modified equation.     

Characterisation of the thermally accessible spin triplet state in dimers of the 7pi ClCNSSS+* in the solid state

[ClCNSSS]2(2+) is the first example of a thiazyl radical dimer where population of a thermally excited spin triplet state has been detected, as is proved by VT-powder and single-crystal EPR spectroscopy.     

State tomography of capacitively shunted phase qubits with high fidelity

We introduce a new design concept for superconducting phase quantum bits (qubits) in which we explicitly separate the capacitive element from the Josephson tunnel junction for improved qubit performance. The number of two-level systems that couple to the qubit is thereby reduced by an order of magnitude and the measurement fidelity improves to 90%. This improved design enables the first demonstration of quantum state tomography with superconducting qubits using single-shot measurements.     

Electron paramagnetic resonance of Cr3+ ions in ferroelastic CsLiSO4

The X-band EPR studies of Cr³⁺-doped LCS have been performed. The values of the spin-Hamiltonian parameters for Cr³⁺ ions have been estimated at room temperature. The effect of crystal twinning on the EPR spectra has also been described. The temperature behaviour of EPR lines originated from two structurally different chromium complexes has been studied close to the ferroelastic phase transition. From the temperature dependence of positions of the split resonance lines a value of the critical exponent β of the order parameter was found to be β = 0.25.     

The influence of compression conditions on the peculiarities of self-propagating exothermal reaction in Al–Ni powder reactive materials

The paper deals with the effect of the compression conditions on the propagation front velocity of exothermal reaction and the specific heat release in Al–Ni powder reactive materials with mean particle sizes of 70–110 nm. It was shown that the velocity increases from 2.7 to 8 cm s^?1 and comes to saturation with the lowering of the porosity (η) from 0.91 to 0.34, while the dependence of the specific heat release has its maximum for η?=?0.5. The results of the X-ray diffraction analysis obtained in situ during the sample heating suggest that the sequence of phase transformations in the system does not depend on the porosity. In all cases, first in the temperature range of ~?500–540 °C the NiAl compound is formed. With the further heating up to ~?640 °C, the Ni₃Al, Ni₂Al₃ and NiAl₃ compounds are additionally formed. The calculation of kinetic parameters was performed using the obtained curves of the differential scanning calorimetry: activation energy, pre-exponential factor and reaction model. The comparison of the calculated results and the scanning electron microscopy data has shown that such behavior of the Al–Ni system with the porosity lowering occurs due to the growth of the transformation degree and is associated with the presence in the final powder mixture of mutually non-contacting Al and Ni agglomerates with the dimensions of over 10 μm.     

Palladium-catalyzed direct heck arylation of dual pi-deficient/pi-excessive heteroaromatics. Synthesis of C-5 arylated imidazo[1,5-a]pyrazines

A general and efficient synthesis of 5-aryl imidazo[1,5- a]pyrazines by palladium-catalyzed coupling of the corresponding 8-substituted derivatives with aryl halides is described. The scope of this new reaction for the imidazo[1,5- a]pyrazine ring system was explored using three readily available 8-substituted precursors, X = NH2, NMe2, and OMe, as well as 8-aryl derivatives, X = Ar'. On the basis of these results as well as studies using a deuterated derivative, a Heck-like mechanism is proposed for this transformation.     

Tuning intermolecular magnetic exchange interactions in the solids C(x)F(2)(x)(CNSSS)(2)(AsF(6))(2): structural, EPR, and magnetic characterization of dimeric (x = 2, 4) diradicals

A series of diradical containing salts CxF2x(CNSSS)2(**2+0(AsF6-)2 {x = 2, 1[AsF6]2; x = 3, 3[AsF6]2; x = 4, 2[AsF6]2} have been prepared. 1[AsF6]2 and 2[AsF6]2 were fully characterized by X-ray, variable-temperature magnetic susceptibility, and solid-state EPR measurements, further allowing us to extend the number of examples of the family of rare 7pi RCNSSS(*+) radical cations. 1[AsF6]2: a = 6.5314(7) A, b = 7.5658(9) A, c = 9.6048(11) A, alpha = 100.962(2) degrees , beta = 96.885(2) degrees , gamma = 107.436(2) degrees , triclinic, space group P, Z = 1, T = 173 K. 2[AsF6]2: a = 10.6398(16) A, b = 7.9680(11) A, c = 12.7468(19) A, beta = 99.758(2) degrees , monoclinic, space group P21/c, Z = 2, T = 173 K. In the solid-state, CxF2x(CNSSS)2(**2+) (x = 2, 4) formed one-dimensional polymeric chains of dications containing discrete centrosymmetric radical pairs in which radicals were linked by four centered two-electron pi*-pi* bonds [12+, d(S...S) = 3.455(1) A; 22+, d(S...S) = 3.306(2) A]. The exchange interactions in these bonds were determined to be -500 +/- 30 and -900 +/- 90 cm-1, by variable temperature magnetic susceptibility measurements, respectively, providing rare experimental data on the singlet-triplet gaps in the field of thiazyl radicals. For 2[AsF6]2, the thermally excited triplet state was unambiguously characterized by EPR techniques [/D/ = 0.0254(8) cm(-1), /E/ = 0.0013(8) cm(-1)]. These experimental data implied a weakly associated nature of the radical moieties contained in the solids 1[AsF6]2 and 2[AsF6]2. Computational analysis of the dimerization process is presented, and we show that the 2c 4 electron pi*-pi* bonds in 1[AsF6]2 and 2[AsF6]2 have ca. 50% and 40% diradical character, respectively. In contrast, 3[AsF6]2.SO2, containing diradical C3F6(CNSSS)2(**2+) with an odd number of CF2 spacers, showed magnetic behavior that was consistent with the presence of monomeric radical centers in the solid state.     

Changes in Antioxidant Properties and Amounts of Bioactive Compounds during Simulated In Vitro Digestion of Wheat Bread Enriched with Plant Extracts

Cereal preparation can be an excellent source of substances with proven health-promoting properties. Unfortunately, some types of bread, such as white flour bread, are devoid of many valuable nutrients. Therefore, it is necessary to look for ways to increase its density and nutritional value. The aim of the study was to investigate the effect of stabilized plant extracts on the quality of bread, its antioxidant activity and polyphenol content, and to evaluate the stability of bioactive compounds and antioxidant activity during in vitro digestion. The research material was the wheat bread baked with spray dried microcapsules of hawthorn bark, soybeans and onion husks in maltodextrin or inulin carriers. The addition of plant extracts resulted in the presence of phenolic compounds in the wheat bread, and its antioxidant activity significantly increased. There was no significant difference in antioxidant activity between breads containing microcapsules with different carriers. During in vitro digestion, procyanidins and isoflavones in bread were more resistant to the digestive processes than other compounds. The antioxidant activity during simulated digestion was the highest at the stage of gastric digestion, and its value depended on the extract used and the analytical method applied.