Efficient transformation of azides to primary amines using the mild and easily accessible CeCl3.7H2O/NaI system

Because of the nitrogen functionality, the azido group plays an important role in the synthesis of amines, and numerous reduction methods of azides to primary amines are reported. Recent reports have highlighted the capability of NaI as a useful reagent for this transformation when it is used in combination with a Lewis acid promoter. However, these methods often suffer from harsh reaction conditions; for this reason, the development of a simple and efficient protocol using NaI in presence of inexpensive and readily available cerium salts Lewis acids would extend the scope of this organic transformation. In continuation of our interest on the use of the CeCl3.7H2O/NaI system, in this paper we report how azides undergo reduction by NaI in the presence of CeCl3.7H2O in refluxing acetonitrile under neutral conditions to produce the corresponding primary amines. The rate and yield of the reaction are considerably improved by employing this microwave-assisted procedure, and this may be of value for the preparation of densely functionalized molecules having biological and pharmaceutical activities.     

Splitting of spin excitations in nanometric rings induced by a magnetic field

We present a Brillouin light scattering investigation of the eigenmode spectrum of nanometric permalloy rings as a function of the applied magnetic field. In particular, different splitting effects induced by the applied magnetic field on the radial and azimuthal excitations have been observed and explained in terms of either mode localization or symmetry. The dynamical matrix approach has been used to calculate the whole set of eigenvectors and eigenvalues of the system, in both the vortex and saturated states.     

Positive cross correlations in a normal-conducting fermionic beam splitter

We investigate a beam-splitter experiment implemented in a normal-conducting fermionic electron gas in the quantum Hall regime. The cross correlations between the current fluctuations in the two exit leads of the three terminal device are found to be negative, zero, or even positive, depending on the scattering mechanism within the device. Reversal of the cross correlation sign occurs due to interaction between different edge states and does not reflect the statistics of the fermionic particles which "antibunch."     

Design and testing of a small-scale sublimation apparatus

In many areas of scientific research and development, for example in the pharmaceutical industry, it is important to prepare and to characterize crystals of pure organic compounds which are thermodynamically stable. The formation of crystals from the gas phase is technically less straightforward than crystallisation from solution, but sublimation techniques can have several important features. In the present paper we report the design and testing of a novel apparatus for small scale sublimation and fractional deposition of crystals. The instrument has been developed with special reference to the needs in the pharmaceutical industry. A few mg of the samples are enclosed, under reduced pressure, in thin-walled glass tubes, along which a well defined temperature gradient can be formed. During an experiment the substance will sublime from the hot end of the glass tube and crystals will be deposited along the temperature gradient. The applicability of the instrument has been verified by experiments with several test compounds. Results from experiments with carbamazepine, are reported in some detail. Carbamazepine single crystals of high quality were obtained and the transition temperature between the triclinic (Form I) and the monoclinic (Form III) crystal modifications agreed with literature values.     

Oxidative NHC-Catalysis as Organocatalytic Platform for the Synthesis of Polyester Oligomers by Step-Growth Polymerization

The application of N-heterocyclic carbene (NHC) catalysis to the polycondensation of diols and dialdehydes under oxidative conditions is herein presented for the synthesis of polyesters using fossil-based (ethylene glycol, phthalaldehydes) and bio-based (furan derivatives, glycerol, isosorbide) monomers. The catalytic dimethyl triazolium/1,8-diazabicyclo[5.4.0]undec-7-ene couple and stoichiometric quinone oxidant afforded polyester oligomers with a number-average molecular weight (M_n) in the range of 1.5–7.8 kg mol⁻¹ as determined by NMR analysis. The synthesis of a higher molecular weight polyester (polyethylene terephthalate, PET) by an NHC-promoted two-step procedure via oligoester intermediates is also illustrated together with the catalyst-controlled preparation of cross-linked or linear polyesters derived from the trifunctional glycerol. The thermal properties (TGA and DSC analyses) of the synthesized oligoesters are also reported.     

Multiplexed Discrimination of Single Amino Acid Residues in Polypeptides in a Single SERS Hot Spot

The SERS‐based detection of protein sequences with single‐residue sensitivity suffers from signal dominance of aromatic amino acid residues and backbones, impeding detection of non‐aromatic amino acid residues. Herein, we trap a gold nanoparticle in a plasmonic nanohole to generate a single SERS hot spot for single‐molecule detection of 2 similar polypeptides (vasopressin and oxytocin) and 10 distinct amino acids that constitute the 2 polypeptides. Significantly, both aromatic and non‐aromatic amino acids are detected and discriminated at the single‐molecule level either at individual amino acid molecules or within the polypeptide chains. Correlated with molecular dynamics simulations, our results suggest that the signal dominance due to large spatial occupancy of aromatic rings of the polypeptide sidechains on gold surfaces can be overcome by the high localization of the single hot spot. The superior spectral and spatial discriminative power of our approach can be applied to single‐protein analysis, fingerprinting, and sequencing.     

Polyextremophilic Chitinolytic Activity by a Marine Strain (IG119) of Clonostachys rosea

The investigation for novel unique extremozymes is a valuable business for which the marine environment has been overlooked. The marine fungus Clonostachys rosea IG119 was tested for growth and chitinolytic enzyme production at different combinations of salinity and pH using response surface methodology. RSM modelling predicted best growth in-between pH 3.0 and 9.0 and at salinity of 0–40‰, and maximum enzyme activity (411.137 IU/L) at pH 6.4 and salinity 0‰; however, quite high production (>390 IU/L) was still predicted at pH 4.5–8.5. The highest growth and activity were obtained, respectively, at pH 4.0 and 8.0, in absence of salt. The crude enzyme was tested at different salinities (0–120‰) and pHs (2.0–13.0). The best activity was achieved at pH 4.0, but it was still high (in-between 3.0 and 12.0) at pH 2.0 and 13.0. Salinity did not affect the activity in all tested conditions. Overall, C. rosea IG119 was able to grow and produce chitinolytic enzymes under polyextremophilic conditions, and its crude enzyme solution showed more evident polyextremophilic features. The promising chitinolytic activity of IG119 and the peculiar characteristics of its chitinolytic enzymes could be suitable for several biotechnological applications (i.e., degradation of salty chitin-rich materials and biocontrol of spoiling organisms, possibly solving some relevant environmental issues).