Three New Polyoxygenated Steroids from Two Species of the South China Sea Gorgonian Muricella flexuosa and Menella verrucosa Brundin

Three new polyoxygenated steroids, muricesteroid ( 1 ), and menellsteroids A ( 2 ) and B ( 3 ), were isolated from two species of the South China Sea gorgonian Muricella flexuosa and Menella verrucosa Brundin , respectively. The structures of these new compounds were elucidated on the basis of extensive spectroscopic analysis, chemical methods and comparison with known related compounds.     

Environmental certification: a scientific tool for sustainability. Evaluation of possible indicators for the environmental performance evaluation (EPE) of Ravenna province (Italy)

Environmental certification is becoming the main tool for application of sustainable development principles. The European Regulation Emas and the international standard ISO 14001 both require for certification, to perform an environmental management system to prevent environmental impacts and to continuously improve environmental performance. For a good environmental performance evaluation (EPE), certification needs to use scientific methodologies and to interface with scientific research; here we proposed emergy analysis as a valid method for EPE and emergetic environmental performance and condition indicators (EPIs, ECIs) to monitor a territorial system: Ravenna province (Italy). Together with emergy indicators were selected other indicators for a deeper EPE: emitted/adsorbed CO2, energy consumptions, air and water pollution measures. The paper showed that Ravenna system has a good environmental performance and demonstrated how different indicators from the most advanced chemical research (chemical-physical, analytical, etc.) contribute to a complete EPE of a complex territorial system and are useful for environmental certification and sustainable development.     

Ferrocene-containing carbohydrate dendrimers

Aliphatic amines, incorporating one or three (branched) acylated beta-D-glucopyranosyl residues, were coupled with the acid chloride of ferrocenecarboxylic acid and with the diacid chloride of 1,1'-ferrocenedicarboxylic acid to afford four dendrimer-type, carbohydrate-coated ferrocene derivatives in good yields (54-92%). Deprotection of the peracylated beta-D-glucopyranosyl residues was achieved quantitatively by using Zemplén conditions, affording four water-soluble ferrocene derivatives. When only one of the two cyclopentadienyl rings of the ferrocene unit is substituted, strong complexes are formed with beta-cyclodextrin in H2O, as demonstrated by liquid secondary ion mass spectrometry (LSIMS), 1H NMR spectroscopy, electrochemical measurements, and circular dichroism spectroscopy. Molecular dynamics calculations showed that the unsubstituted cyclopentadienyl ring is inserted through the cavity of the toroidal host in these complexes. The electrochemical behavior of the protected and deprotected ferrocene-containing dendrimers was investigated in acetonitrile and water, respectively. The diffusion coefficient decreases with increasing molecular weight of the compound. The potential for oxidation of the ferrocene core, the rate constant of heterogeneous electron transfer, and the rate constant for the energy-transfer reaction with the luminescent excited state of the [Ru(bpy)3]2+ complex (bpy = 2,2'-bipyridine) are strongly affected by the number (one or two) of substituents and by the number (one or three) of carbohydrate branches present in the substituents. These effects are assigned to shielding of the ferrocene core by the dendritic branches. Electrochemical evidence for the existence of different conformers for one of the dendrimers in aqueous solution was obtained.     

Trinuclear pyrazine-bridged ruthenium complexes: syntheses, electrochemistry, NIR-Vis spectra, and their interpretation in terms of a 5-orbital-3-parameter model

A study of absorption spectra in the near-infrared (NIR) and visible (vis) regions of trinuclear Ru complexes containing pyrazine (pyz) as bridging ligand, trans-[(Ru(NH(3))(5)pyz)(2)Ru(NH(3))(4)](m+)(m = 6-9), is reported. The spectra were recorded on aqueous solutions containing the described species formed in situ by stoichiometric additions of a standard solution of Ce(SO(4))(2). They were interpreted in terms of a simple 5-orbital-3-parameter model which includes the effects of d-pi interaction and electronic correlation. The model is shown to account for the observed NIR-vis spectra of the complex ions. The 6+ parent species was synthesized by an improved literature method and fully characterized. The novel 8+ complex was also prepared and characterized. The 9+ ion was established to be slowly reduced by water, with dioxygen formation. Electrochemical (CV and DPV) studies were performed on the trinuclear 6+ complex, as well as on its constituent fragments [Ru(NH(3))(5)(pyz)](2+) and trans-[Ru(NH(3))(4)(pyz)(2)](2+).     

A Silver Monochrome “Concetto spaziale” by Lucio Fontana: A Spectroscopic Non- and Micro-Invasive Investigation of Materials

In several of his artworks, for instance the Venezie cycle, Fontana employed metallic paints; previous investigations on such materials highlighted the use of different synthetic binders and of thick paint layers below the metal one, having different colours to change the visual perception of the metallic surface. In the present work, a monochrome silver “Concetto spaziale” by the Italo–Argentine artist belonging to a private collection recently gifted to the museum of the Church of San Fedele in Milano, Italy, was investigated to deepen the knowledge of this particular group of Fontana’s paintings. The artwork was initially visually inspected in visible and ultraviolet (UV) light. Subsequently, a non-invasive spectroscopic investigation was performed by X-ray fluorescence (XRF), reflection Fourier-transform infrared (FTIR) and Raman spectroscopy. A minute fragment of silver-coloured paint was taken from the reverse of the painting, near the cut edge, and examined by scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX) and micro-Fourier-transform Raman (FT-Raman) spectroscopy. The analytical data made it possible to identify the composition of the metallic paint layer and of the underlying dark one, both from the point of view of the pigments and of the binders used, also highlighting the potential of the non-invasive and micro-invasive methods adopted in the investigation.     

Negishi cross-coupling of arenediazonium o-benzenedisulfonimides

Diazonium salts, precisely arenediazonium o-benzenedisulfonimides, have been used for the first time as efficient electrophilic partners in Negishi coupling reactions. The synthetic protocol was general, easy and gave biaryls in satisfactory yields (34 examples, average yield 69%). o-Benzenedisulfonimide was recovered at the end of the reactions and reused to prepare the starting salts once again.     

Many body effects in the electronic and optical properties of the (1 1 1) surface of diamond

The (1 1 1) face is the cleavage surface of diamond. Understanding its properties is very important for the growing technological interest on the chemistry of diamond surfaces. Within DFT the most stable reconstruction is the Pandey chain model, the atoms on the chain being neither buckled nor dimerised. However this geometry gives rise to a semi metallic band structure in contrast with experimental findings that show the presence of a gap ranging from 0.5 to 2 eV. Here we show that the same equilibrium geometry and thus the same metallic band structure is found relaxing the surface using screened exchange (sX) or Hartree-Fock (HF) functionals. We will discuss in detail how breaking the equivalence of the atoms on the chain affects the band structure and we will show that a buckling would yield a semiconducting surface, but is energetically unfavorable. A semiconducting character can be restored, within the equilibrium geometry, if quasiparticle corrections are carefully included within an iterative GW scheme. The result of the theoretical reflectance anisotropy spectra (RAS) at a DFT-RPA level are also presented and discussed. As expected, a strong anisotropy signal is found at low energies due to transitions between surface states inside the fundamental gap.     

Gold catalysed Suzuki-Miyaura coupling of arenediazonium o-benzenedisulfonimides

Arenediazonium o-benzenedisulfonimides have been used as efficient electrophilic partners in Au(I) catalysed Suzuki coupling reactions. The synthetic protocol is general, easy and produced either biaryls or heteroaryl arenes in good yields (51 positive examples, average yield 80%). o-Benzenedisulfonimide was recovered at the end of the reactions and was reused to prepare the starting salts for further reactions. Mechanistic insights suggest that the o-benzenedisulfonimide anion act as an electron transfer agent and promotes a catalytic cycle which does not require the presence of photocatalysts or external oxidants.     

Determination of dimethylarginine levels in rats using HILIC-MS/MS: an in vivo microdialysis study

Nitric oxide (NO) is one of the most important mediators and neurotransmitters and its levels change under pathological conditions. NO production may be regulated by endogenous nitric oxide synthase (NOS) inhibitors, in particular asymmetric dimethylarginine (ADMA). Most of the interest is focused on ADMA, since this compound is present in plasma and urine and accumulation of ADMA has been described in many disease states but little is known about cerebrospinal fluid (CSF) concentrations of this compound and of its structural isomer symmetric dimethylarginine (SDMA). To determine the levels of methylarginines, we here present a new hydrophilic interaction chromatography (HILIC)-MS/MS method for the precise determination of these substances in CSF from microdialysis samples of rat prefrontal cortex (PFC). The method requires only minimal sample preparation and features isotope-labelled internal standards.     

Specific anions effects of on the stability of azurin in ice

This investigation represents a first attempt to gain a quantitative estimate of the effects of the anions sulfate, citrate, acetate, chloride and thiocyanate on the thermodynamic stability (DeltaG degrees) of a model globular protein in ice at -15 degrees C. The method, based on guanidinium chloride denaturation of the azurin mutant C112S from Pseudomonas aeruginosa, distinguishes between the effects of cooling to subfreezing temperatures from those induced specifically by the formation of a solid ice phase. The results confirm that, both in liquid and frozen states, kosmotropes (sulfate, citrate and acetate) increase significantly protein stability, relative to chloride, whereas the chaotrope thiocyanate decreases it. Throughout, their stabilizing efficacy was found to rank according to the Hofmeister series, sulfate>citrate>acetate>chloride>thiocyanate, although the magnitude of Delta(DeltaG degrees) exhibited a distinct sensitivity among the anions to low temperature and to ice formation. In the liquid state, lowering the temperature from +20 to -15 degreesC weakens considerably the stabilizing efficacy of the organic anions citrate and acetate. Among the anions sulfate stands out as the only strong stabilizer at subfreezing temperatures while SCN- becomes an even stronger denaturant. Freezing of the solution in the presence the "neutral" salt NaCl destabilizes the protein, DeltaG degrees progressively decreasing up to 3-4 kcal/mol as the fraction of liquid water in equilibrium with ice (VL) is reduced to less than 1%. Kosmotropes do attenuate the decrease in protein stability in ice although in the case of citrate and acetate, their efficacy diminishes sharply as the liquid fraction shrinks to below 2.7%. On the contrary, sulfate is remarkable for it maintains constantly high the stability of azurin in liquid and frozen solutions, down to the smallest VL (0.5%) examined. Throughout, the reduction in DeltaG degrees caused by the solidification of water correlates with the decrease in the denaturant m value, an indirect indication that protein-ice interactions generally lead to partial unfolding of the native state. It is proposed that binding of the kosmotropes to the ice interface may inhibit protein adsorption to the solid phase and thereby counter the ice perturbation.