Dissolution and Doping of Polyaniline Emeraldine Base in Imidazolium Ionic Liquids Investigated by Spectroscopic Techniques

Polyaniline is a model molecular system in the study of conductive polymers. Ionic liquids, on the other hand, are becoming more and more a very convenient alternative for conventional organic solvents. The dissolution of polyaniline‐emeraldine base (PANI‐EB) in imidazolium ILs leads to its doping, as indicated by optical and resonance Raman spectroscopies. In this study, it is proposed that the interaction of PANI‐EB and imidazolium ILs involves the specific interaction of the quinoid moiety of the former with the imidazolium ring of the latter, an interpretation that is also based on N K‐edge XANES measurements of neat PANI‐EB, neat ILs, and of their solutions.

     

Suberitane sesterterpenoids from the Antarctic sponge Phorbas areolatus (Thiele, 1905)

Following ecological and chemical screenings, the Antarctic sponge Phorbas areolatus was chemically investigated for the first time. Three new suberitane derivatives named isosuberitenone B, 19-episuberitenone B, and isoxaspirosuberitenone were identified together with the known compounds suberitenones A and B, and oxaspirosuberitenone after a thorough inspection of their NMR data. These compounds were found to exhibit moderate cytotoxic activity and their presence in this sponge rules out their use as a chemotaxonomic marker for Suberites sponges.     

A Zn(II) luminescent complex with a Schiff base ligand: solution,computational and solid state studies

Abstract

A new mononuclear complex of zinc(II), [Zn(HL)₂]?2DMF (H₂L = (E)-N′-((E)-(hydroxyimino)butan-2-ylidene)salicyloylhydrazide, DMF = N,N-dimethylformamide), was prepared and characterized. Single-crystal X-ray crystallography revealed a six-coordinate zinc(II) surrounded by nitrogen of the oxime function and oxygen and distal nitrogens of the acylhydrazone group. This entity also exists in solution as demonstrated by ¹H-NMR and potentiometric titrations. The computational analysis showed that the molecular orbitals involved in the main electronic transitions of the complex species in solution are centered on the ligand with negligible contribution of the metal ion. The photophysical properties of the complex were evaluated in solution and in the solid state. Luminescence studies showed that the solid has a strong emission at 550 nm with a large Stokes shift with respect to absorption. The solid state fluorescence emission is ascribed to ligand-centered and/or ligand-to-ligand charge transfer transitions, following the DFT results in solution. A comparison with a previously reported mononuclear [Zn(HL)₂] allowed the investigation of the influence of DMF molecules in the structural packing and the luminescence properties.     

“Smart” Polymers: Physicochemical Characteristics and Applications in Bio-Separation Strategies

In recent years, smart polymers (SPs), which are also referred to as bio-responsive polymers, have gained considerable attention as a unique class of polymers and their applications have been increasing significantly. These so-called “smart” polymers, either synthetic or biological, have been defined as “polymers designed to respond or undergo physical and structural conformational changes/rearrangement in response to slight changes in their surrounding environment”. They are categorized as thermo-, pH-, electro- and magneto-responsive polymers. The advances in upstream bio-production stages and the high cost associated with downstream chromatographic techniques have pushed the development of new alternatives. In this context, the use of SPs, in combination with non-chromatographic technologies, represents a useful approach to the development of new downstream operation units. With the key scientific advancements, SPs have become the “next generation” of the bio-separation tool for eco-friendlier and cost-effective purification. This review describes the different characteristics and classifications of various “smart” polymers available for use in bio-separation strategy. Focus is also given to the recent advances in SP inclusion in the improvement of alternative non-chromatographic methods in downstream bioprocessings.     

Photochemistry of 6‐Formylpterin in Alkaline Medium

6‐formylpterin solutions at pH 11 were photolyzed at 350 nm at room temperature. The photochemical reactions were followed by UV/VIS spectrophotometry, thin layer chromatography (TLC), and high‐performance liquid chromatography (HPLC). In the presence of oxygen, 6‐carboxypterin is the only photoproduct detected by the analytical techniques mentioned. In the absence of oxygen, a new compound showing an absorbance maximum at 480 nm is observed. The latter compound is thermally oxidized very fast in the presence of oxygen to 6‐carboxypterin. The quantum yields of substrate disappearance and of photoproduct formation are reported     

Electrocatalysis of As(III) oxidation by cobalt oxide nanoparticles: measurement and modeling the effect of nanoparticle amount on As(III) oxidation potential

Journal of Solid State Electrochemistry - The performance of electrodes modified with electrochemically generated cobalt oxide nanoparticles for the oxidation of As(III) species was investigated by...     

Determining concentration depth profiles in fluorinated networks by means of electric force microscopy

By means of electric force microscopy, composition depth profiles were measured with nanometric resolution for a series of fluorinated networks. By mapping the dielectric permittivity along a line going from the surface to the bulk, we were able to experimentally access to the fluorine concentration profile. Obtained data show composition gradient lengths ranging from 30 nm to 80 nm in the near surface area for samples containing from 0.5 to 5 wt. % F, respectively. In contrast, no gradients of concentration were detected in bulk. This method has several advantages over other techniques because it allows profiling directly on a sectional cut of the sample. By combining the obtained results with x-ray photoelectron spectroscopy measurements, we were also able to quantify F/C ratio as a function of depth with nanoscale resolution.