Sterically stabilized cyclopropenonophanes and an electronically stabilized cyclopropenethionophane: syntheses, structural properties, and reactivity

The syntheses of sterically stabilized cyclopropenonophanes as well as an electronically stabilized cyclopropenethionophane are reported, and their molecular structures in the solid state are elucidated. The sulfur of the CS moiety in cyclopropenethiones was shown to react as a nucleophile. Temperatures of more than 240 degrees C favor the extrusion of CO in the cyclopropenonophane to afford an alpha,alpha'-tetramethyl-substituted cyclodiyne. [reaction: see text]     

In vivo optical properties of normal canine prostate at 732 nm using motexafin lutetium-mediated photodynamic therapy

The optical properties (absorption [mu(a)], transport scattering [mu('s)] and effective attenuation [mu(eff)] coefficients) of normal canine prostate were measured in vivo using interstitial isotropic detectors. Measurements were made at 732 nm before, during and after motexafin lutetium (MLu)-mediated photodynamic therapy (PDT). They were derived by applying the diffusion theory to the in vivo peak fluence rates measured at several distances (3, 6, 9, 12 and 15 mm) from the central axis of a 2.5 cm cylindrical diffusing fiber (CDF). Mu(a) and mu('s) varied between 0.03-0.58 and 1.0-20 cm(-1), respectively. Mu(a) was proportional to the concentration of MLu.Mu(eff) varied between 0.33 and 4.9 cm(-1) (mean 1.3 +/- 1.1 cm(-1)), corresponding to an optical penetration depth (8 = 1/(mu(eff)) of 0.5-3 cm (mean 1.3 +/- 0.8 cm). The mean light fluence rate at 0.5 cm from the CDF was 126 +/- 48 mW/cm2 (N = 22) when the total power from the fiber was 375 mW (150 mW/cm). This study showed significant inter- and intraprostatic differences in the optical properties, suggesting that a real-time dosimetry measurement and feedback system for monitoring light fluences during treatment should be advocated for future PDT studies. However, no significant changes were observed before, during and after PDT within a single treatment site.     

Development of perfluoroarene-arene interactions for macrocyclic en-yne metathesis and the total synthesis of macrocyclic natural products

Efficient direct en-yne metathesis of strained macrocyclic systems is possible using highly active Grubbs-Hoveyda second-generation catalyst and when exploiting fluoroarene-arene gearing interactions. These interactions are effective even under high reaction temperatures and in the presence of a competitive pi-rich solvent such as toluene. These results suggest that efficient pi-pi stacking or pi-lp interactions between auxiliaries containing pentafluorophenyl and 3,5-bis(trifluoromethyl)phenyl groups are responsible for the good yields of macrocyclization products. The 3,5-bis(trifluoromethyl)benzyl gearing elements provide higher yields and greater E-selectivity in the macrocyclic en-yne metathesis to form model paracyclophanes that could be applied toward the preparation of members of the longithorone family of natural products.     

Uncovering new properties of imidazolium salts: Cl- transport and supramolecular regulation of their transmembrane activity

We report the Cl(-) transport activity for three imidazolium-based transporters. We present significant findings regarding the use of α-cyclodextrin and cucurbit[7]uril macrocycles to form inclusion complexes with these salts and to inhibit their membrane activity.     

Green Synthesis,Characterization, and Antibacterial Properties of Silver Nanoparticles Obtained by Using Diverse Varieties of Cannabis sativa Leaf Extracts

Cannabis sativa L. (hemp) is a plant used in the textile industry and green building material industry, as well as for the phytoremediation of soil, medical treatments, and supplementary food products. The synergistic effect of terpenes, flavonoids, and cannabinoids in hemp extracts may mediate the biogenic synthesis of metal nanoparticles. In this study, the chemical composition of aqueous leaf extracts of three varieties of Romanian hemp (two monoecious, and one dioecious) have been determined by Fourier-Transformed Infrared spectroscopy (FT-IR), high-performance liquid chromatography, and mass spectrometry (UHPLC-DAD-MS). Then, their capability to mediate the green synthesis of silver nanoparticles (AgNPs) and their pottential antibacterial applications were evaluated. The average antioxidant capacity of the extracts had 18.4 ± 3.9% inhibition determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) and 78.2 ± 4.1% determined by 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS™) assays. The total polyphenolic content of the extracts was 1642 ± 32 mg gallic acid equivalent (GAE) L⁻¹. After this, these extracts were reacted with an aqueous solution of AgNO₃ resulting in AgNPs, which were characterized by UV−VIS spectroscopy, FT-IR, scanning electron microscopy (SEM-EDX), and dynamic light scattering (DLS). The results demonstrated obtaining spherical, stable AgNPs with a diameter of less than 69 nm and an absorbance peak at 435 nm. The mixture of extracts and AgNPs showed a superior antioxidant capacity of 2.3 ± 0.4% inhibition determined by the DPPH^• assay, 88.5 ± 0.9% inhibition as determined by the ABTS^•+ assay, and a good antibacterial activity against several human pathogens: Escherichia coli, Klebsiella pneumoniae, Pseudomonas fluorescens, and Staphylococcus aureus.     

Evaluation of Hepatoprotective Activity and Oxidative Stress Reduction of Rosmarinus officinalis L. Shoots Tincture in Rats with Experimentally Induced Hepatotoxicity

Rosmarinus officinalis L. is a widely known species for its medicinal uses, that is also used as raw material for the food and cosmetic industry. The aim of the present study was to offer a novel perspective on the medicinal product originating from this species and to test its hepatoprotective activity. The tested sample consisted in a tincture obtained from the fresh young shoots. Compounds that are evaluated for this activity are polyphenols and terpenoids, that are identified and quantified by HPLC–UV–MS and GC–MS. Antioxidant activity was assessed in vitro, using the DPPH, FRAP and SO assays. Hepatoprotective activity was tested in rats with experimentally-induced hepatotoxicity. In the chemical composition of the tincture, phenolic diterpenes (carnosic acid, carnosol, rosmanol, rosmadial) and rosmarinic acid were found to be the majority compounds, alongside with 1,8-cineole, camphene, linalool, borneol and terpineol among monoterpenes. In vitro, the tested tincture proved significant antioxidant capacity. Results of the in vivo experiment showed that hepatoprotective activity is based on an antioxidant mechanism. In this way, the present study offers a novel perspective on the medicinal uses of the species, proving significant amounts of polyphenols and terpenes in the composition of the fresh young shoots tincture, that has proved hepatoprotective activity through an antioxidant mechanism.     

Acylmethyl(aryl)tellurium(IV,II) derivatives: intramolecular secondary bonding and steric rigidity

Electrophilic substitution of acylmethanes (methyl ketones), RCOCH3 (R = i-Pr, 1; Et, 2; Me, 3) with aryltellurium trichlorides, ArTeCl3 (Ar = 1-C10H7, Np, A; 2,4,6-Me3C6H2, Mes, B; 4-MeOC6H4, Anisyl, C) under mild conditions affords the corresponding acylmethyl(aryl)tellurium dichlorides (RCOCH2)ArTeCl2. Reduction of the dichlorides, gives tellurides, (i-PrCOCH2)ArTe, 1A-1C, which give the corresponding dihalides, (i-PrCOCH2)ArTeX2 (X = Cl, 1Aa-1Ca; Br, 1Ab-1Cb; I, 1Ac-1Cc) when reacted in situ with SO2Cl2, Br2 or I2. The unsymmetric tellurides are labile towards disproportionation and attempts to obtain them lead to the isolation of Ar2Te2 except in the case of (i-PrCOCH2)MesTe (1B), which represents an interesting example of a kinetically stable aryl(alkyl)telluride. All the dihalomesityltellurium(IV) derivatives show separate 1H and 13C NMR signals for the ortho methyls irrespective of the sizes of R and X ligands. The telluride, 1B with free rotation about Te-C(mesityl) bond shows, like the unsymmetric diorganotellurium(IV) dihalides, only one 125Te NMR signal. The 1,4-chelating behavior of the acyl ligand among diorganotellurium(IV) compounds is inferred from the X-ray diffraction data for 1Aa, 1Ac, 1Ba, 1Bb, 1cA and 1Cc which are indicative of the presence of intramolecular Te...O secondary bonding interactions (SBIs) at least in the solid state. As a consequence, steric repulsion in case of the mesityltellurium(IV) derivatives, 1Ba and 1Bb, reaches the threshold so as to cause loss of two-fold rotational symmetry of the mesityl group about the Te-C(mesityl) bond axis. Intermolecular C-HO...O H-bonding interactions appears to stabilize such an orientation of the aryl ligand at least in the solid state.     

Cellulose derivative/barium titanate composites with high refractive index,conductivity and energy density

Cellulose - This work deals with hydroxypropyl cellulose (HPC)/barium titanate (BT) composites, having small levels of perovskite-like BT loading, i.e. 0.5–2% and being designed for electric...     

Evaluation of thermal and radiation stability of EPDM in the presence of some algal powders

Journal of Thermal Analysis and Calorimetry - In this paper, ecological-friendly materials based on ethylene–propylene–diene terpolymer (EPDM) with improved thermal and radiation...