A convenient MnIII starting material for the synthesis of homo- and heterometallic manganese carboxylate clusters: Mn9 and Mn10−xFex complexes

The use of a convenient source of Mn^III ions, namely the [Mn(OR)(O₂CR′)₂]_n (R = H, Me, and R′ = Me, Bu^t) family of 1-D coordination polymers, afforded two new enneanuclear and decanuclear molecular clusters, homometallic [Mn₉O₇(O₂CBu^t)₁₃(MeCN)₂] (3) and heterometallic [Mn_10?xFe_x(OMe)₂₀(O₂CMe)₁₀] (x < 10) (4), respectively. Compound 3 was synthesized by a solvent-induced structural transformation, whereas complex 4 resulted from the reaction of [Mn(OH)(O₂CMe)₂]_n with an Fe^III source. The core of 3 comprises two [Mn₄O₂]⁸⁺ butterfly units and a [Mn₃O]⁷⁺ triangular unit fused together by sharing one Mn atom. Magnetic susceptibility measurements of 3 revealed dominant antiferromagnetic interactions within the molecule, and a ground state of S = 1 with many low-lying excited states. Complex 4 is a mixed Fe^III/Mn^III single-strand molecular wheel, which forms 3D nanotubular stacks arranged in a zig–zag fashion. The described work suggests that the [Mn(OR)(O₂CR′)₂]_n compounds represent excellent starting materials for Mn^III carboxylate cluster chemistry.     

Novel disposable microfabricated antimony-film electrodes for adsorptive stripping analysis of trace Ni(II)

This work describes a novel type of antimony electrode for adsorptive stripping voltammetry (AdSV). The electrode was microfabricated by coating a silicon chip with a thin antimony-film by means of sputtering and the active area of the electrode was defined by photolithography. The resulting antimony-film electrodes (SbFEs) were characterized by optical and electrochemical techniques. The sensors were tested for the detection of low concentrations of Ni(II) by AdSV in the presence of dimethylglyoxime. Well-formed stripping peaks and a linear dependence of the stripping peak current on the Ni(II) concentration were observed on the microfabricated SbFEs while comparative measurements attempted with electroplated SbFEs were unsuccessful. Utilizing thin-film technology for the formation of the antimony-film extends the scope of these devices as mercury-free sensors in AdSV.     

Self-induced transparency in diblock copolymer dispersions

We report on the versatile effect of weak red laser light impinging on diblock copolymer [poly(isoprene-b-styrene)] dispersions in two selective solvents for each block. In the strongly scattering but transparent micellar solutions in hexane (a good solvent for polyisoprene), higher refractive index copolymer-rich fibers were formed. In the turbid dispersions of the same copolymer in ethyl acetate (a good solvent for polystyrene), the effect of self-induced transparency was observed. A two-step patterning mechanism caused the generation of a transparent microchannel, increasing light transmission. The analogy between the current effect and that observed in homopolymer polyisoprene solutions in different solvents is discussed toward an understanding of the unanticipated light-soft-matter interaction.     

Changes of gross gamma-ray intensity in a submarine spring system due to a distant earthquake event on 30th of March 2019 at Itea,Greece

Journal of Radioanalytical and Nuclear Chemistry - A medium resolution underwater in-situ gamma-ray spectrometer (GeoMAREA) was deployed in the submarine spring (Kiveri) for continuous monitoring...     

Synthesis of novel PPARα/γ dual agonists as potential drugs for the treatment of the metabolic syndrome and diabetes type II designed using a new de novo design program PROTOBUILD

Peroxisome proliferator activated receptors (PPARs) have been shown to have critical roles in fatty acid oxidation, triglyceride synthesis, and lipid metabolism - making them an important target in drug discovery. Here we describe the in silico design, synthesis and in vitro characterisation of a novel series of 2,5-disubstituted indoles as PPARα/γ dual agonists. PPAR activation assays are performed with known agonists diazabenzene (WY14.643), aminopyridine (BRL49653) and bisaryl (L165.041), as positive controls. All the indole compounds synthesized are found to be active PPARα and PPARγ agonists, with particular efficacy from those with 2-naphthylmethyl substitution. This is a useful demonstration of a new de novo design methodology implemented by the protobuild program and its ability to rapidly produce novel modulators for a well characterized drug target.     

Crystal structures, EPR and magnetic properties of 2-ClC6H4CNSSN˙ and 2,5-Cl2C6H3CNSSN˙

The β-sheet structure associated with chlorinated aromatics (d(Cl···Cl)≈ 4.0 ?) has been implemented to drive formation of π-stacked structures of dithiadiazolyl radicals. Both title compounds exhibit an increase in paramagnetism above 150 K but solid-state EPR studies indicate that the origin of the paramagnetism in these two systems is different.     

Determination of the thiol redox state of organisms: new oxidative stress indicators

This study describes a new methodology by which the concentrations of non-protein (NP) thiols glutathione (GSH), cysteine (CSH), N-acetylcysteine (AcCSH), and protein (P) thiols (PSH), as well as the contribution of these components to symmetric and mixed disulfides (NPSSR, NPSSC, NPSSCAc, PSSR, PSSC, PSSCAc, PSSP) can reliably be measured. The methodology consists of a strict sequence of methods which are applied to every sample. Free thiols at any given state of the procedure are measured by Ellmans assay, the CSH fraction is measured by its unique response in the ninhydrin assay, AcCSH is selectively measured with ninhydrin after enzymatic deacylation, proteins are separated from non-protein thiols/disulfides by precipitation with trichloroacetic or perchloric acid, disulfides are reduced into free thiols with borohydride, mixed disulfides between a protein and a non-protein component are measured by extracting the non-protein thiol from the protein pellet after borohydride treatment, and protein thiols/disulfides are measured after resolubilization of the protein pellet.When this method was applied to animal and fungal tissue, new molecular indicators of the thiol redox state of living cells were identified. The findings of the present study clearly show that the new parameters are very sensitive indicators of redox state, while at the same time the traditional parameters GSH and GSSG often remain constant even upon dramatic changes in the overall redox state of biological tissue. Therefore, unbiased assessment of the redox state also requires explicit measurement of its most sensitive thiol indicators.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material.     

DFT study of the mechanism of benzocyclobutene formation by palladium-catalysed C(sp3)-H activation: role of the nature of the base and the phosphine

DFT(B3PW91) calculations of the mechanism of the intramolecular C(sp(3))-H arylation of 2-bromo-tert-butylbenzene to form benzocyclobutene catalysed by Pd(PR(3)) (R = Me, (t)Bu) and a base (acetate, bicarbonate, carbonate) show that the preferred mechanism is highly dependent on the nature of the phosphine and the base used in the calculations. With the experimental reagents (P(t)Bu(3) and carbonate) the rate-determining step is C-H activation with the base coordinated trans to the C-H bond. An agostic interaction of a geminal C-H bond with respect to the bond to be cleaved induces a lowering of the activation barrier.     

An Interpenetrated Framework Material with Hysteretic CO2 Uptake

A new, twofold interpenetrated metal–organic framework (MOF) material has been synthesized that demonstrates dramatic steps in the adsorption and hysteresis in the desorption of CO₂. Measurement of the structure by powder X‐ray diffraction (PXRD) and pair distribution function (PDF) analysis indicates that structural changes upon CO₂ sorption most likely involve the interpenetrated frameworks moving with respect to each other.