Effect of limonene on the frontal ring opening metathesis polymerization of dicyclopentadiene

The frontal ring opening metathesis polymerization (FROMP) of dicyclopentadiene (DCPD) in the presence of limonene, using second generation Grubbs’ catalysts, is reported. The effect of limonene on the amount of catalyst and the typical frontal polymerization parameters, as maximum temperature (T_max) and velocity of the front (V_f), is studied. In addition, the influence of limonene on the mechanical properties of the polymeric samples is reported. Finally, a deep study on the swelling properties of polymers is done. It has been demonstrated that limonene acts as both inhibitor and solvent of the catalyst. The T_max, V_f, T_g, and Young modulus values decrease as the amount of limonene increases, and the polymer samples swell in THF depending on the amount of limonene. All results indicate that the limonene addition on FROMP of results in advantages on the polymerization reaction and its parameters and on the final polymer properties. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 63–68     

Profiling and quantifying polar lipids in milk by hydrophilic interaction liquid chromatography coupled with evaporative light-scattering and mass spectrometry detection

In this work, a high-performance liquid chromatography with evaporative light scattering detection method has been developed and applied for quantification of the polar content of the lipid fraction in milk samples of different origin. From a chromatographic stand-point, a 4.6-mm I.D. hydrophilic interaction liquid chromatography column was employed to attain a baseline separation of major phospholipid classes contained in the various milk samples tested. Quantitative analysis was performed by the external calibration method using reference material solutions in the 5–100 mg/L concentration range. Analytical recoveries ranging from 57 to 100 %, and repeatability data lower than 8.04 % were obtained on a skimmed cow’s milk sample. The crude cow milk was the most abundant (0.04 %) in phospholipids and donkey milk was the poorest (0.004 %). Quantitative differences were determined in the phospholipid content of the milk samples tested. Finally, characterization of phospholipid profile and fatty acid composition of the different samples was carried out by an ion trap-time of flight mass spectrometer and gas chromatography coupled to flame ionization and mass spectrometry detection. A thorough screening of the polar lipid composition of milk samples of different origin is here outlined, for the first time.     

A Facile Syntheses of 6-Bicyclo[3.2.1]octanones

Copper oxide-catalyzed decomposition of 1-diazoacetyl-1-methyl-3-methylenecyclohexanes produces strained tricycles whose reduction or hydrolysis affords 6-bicyclo[3.2.1]octanones.     

Conformational investigation of some macrobicyclic compounds and of their monoprotonated cations through a comparison between X-ray crystal structures and molecular dynamics simulations

Abstract

In preceding works, which have dealt with the synthesis and characterisation of a series of macrobicyclic compounds with five donor atoms, the unusually high basicity constants of these polyaminic cage-like molecules have been ascribed to the inclusion of the proton inside the macrobicyclic cavity which results in a very efficient hydrogen-bond network. The present paper, based on previously reported X-ray crystal structures regarding five-atoms bridging units and on molecular modelling studies shows that the disposition of the five donor atoms in the monoprotonated species is related to the protonation site. Precisely, if the protonation occurs on a bridge-head nitrogen the resulting geometry of the donors is a trigonal bipyramid, whereas it is square pyramidal when the proton is bound to a nitrogen belonging to a macrobicyclic chain. For what concerns the geometrical array of the donor atoms in the free amines, the favoured array seems to be the trigonal bipyramidal.     

Electrochemical detection of miRNA-222 by use of a magnetic bead-based bioassay

MicroRNAs (miRNAs, miRs) are naturally occurring small RNAs (approximately 22 nucleotides in length) that have critical functions in a variety of biological processes, including tumorigenesis. They are an important target for detection technology for future medical diagnostics. In this paper we report an electrochemical method for miRNA detection based on paramagnetic beads and enzyme amplification. In particular, miR 222 was chosen as model sequence, because of its involvement in brain, lung, and liver cancers. The proposed bioassay is based on biotinylated DNA capture probes immobilized on streptavidin-coated paramagnetic beads. Total RNA was extracted from the cell sample, enriched for small RNA, biotinylated, and then hybridized with the capture probe on the beads. The beads were then incubated with streptavidin–alkaline phosphatase and exposed to the appropriate enzymatic substrate. The product of the enzymatic reaction was electrochemically monitored. The assay was finally tested with a compact microfluidic device which enables multiplexed analysis of eight different samples with a detection limit of 7 pmol L^?1 and RSD?=?15 %. RNA samples from non-small-cell lung cancer and glioblastoma cell lines were also analyzed.     

Single nucleotide polymorphism detection by optical DNA-based sensing coupled with whole genomic amplification

The work presented here deals with the optimization of a strategy for detection of single nucleotide polymorphisms based on surface plasmon resonance imaging. First, a sandwich-like assay was designed, and oligonucleotide sequences were computationally selected in order to study optimized conditions for the detection of the rs1045642 single nucleotide polymorphism in the gene ABCB1. Then the strategy was optimized on a surface plasmon resonance imaging biosensor using synthetic DNA sequences in order to evaluate the best conditions for the detection of a single mismatching base. Finally, the assay was tested on DNA extracted from human blood which was subsequently amplified using a whole genome amplification kit. The direct detection of the polymorphism was successfully achieved. The biochip was highly regenerable and reusable for up to 20 measurements. Furthermore, coupling these promising results with the multiarray assay, we can foresee applying this biosensor in clinical research extended to concurrent analysis of different polymorphisms.     

Formation of T‐Shaped versus Charge‐Transfer Molecular Adducts in the Reactions Between Bis(thiocarbonyl) Donors and Br2 and I2

The reactions of 4,5,6,7‐tetrathiocino‐[1,2‐b:3,4‐b′]‐1,3,8,10‐tetrasubstituted‐diimidazolyl‐2,9‐dithiones (R₂,R′₂‐todit; 1 : R=R′=Et; 2 : R=R′=Ph; 3 : R=Et, R′=Ph) with Br₂ exclusively afforded 1:1 and 1:2 “T‐shaped” adducts, as established by FT‐Raman spectroscopy and single‐crystal X‐ray diffraction in the case of complex 1? 2 Br₂. On the other hand, the reactions of compounds 1 – 3 with molecular I₂ provided charge‐transfer (CT) “spoke” adducts, among which the solvated species 3? 2 I₂ ? (1?x)I₂ ? x CH₂Cl₂ (x=0.94) and ( 3 )₂ ? 7 I₂ ? x CH₂Cl_2, (x=0.66) were structurally characterized. The nature of all of the reaction products was elucidated based on elemental analysis and FT‐Raman spectroscopy and supported by theoretical calculations at the DFT level.     

Chemistry of Ethanediyl S,S-Acetals 9-Asymmetric Synthesis of Chiral cis Allylic Alcohols

(2Z,1S)-1,3-diphenyl-2-propenol (3) is obtained from the chiral 5,6-dihydro-1,4-dithiin 1b in two steps and 60% enantiomeric excess. Combining our previously reported stereoselective double bond formation and this 1,4 asymmetric induction introduces a new route to chiral allylic alcohols with cis geometry from simple aldehydes and methyl ketones.     

Design and Synthesis of a γ1β8‐Cyclodextrin Oligomer: A New Platform with Potential Application as a Dendrimeric Multicarrier

We report the synthesis and characterization of a water‐soluble, star‐shaped macromolecular platform consisting of eight β‐cyclodextrin (β‐CD) units anchored to the narrower rim of a γ‐CD core through bis(triazolyl)alkyl spacers. The efficient synthetic protocol is based on the microwave (MW)‐promoted Cu‐catalyzed 1,3‐dipolar cycloaddition of CD monoazides to CD monoacetylenes. The ligand‐hosting capability of the construct has been assessed by relaxometric titration and nuclear magnetic relaxation dispersion (NMRD) profiling, which showed it to be good, and this was supported by molecular dynamics simulations. To demonstrate the feasibility of obtaining supramolecular structures with high hosting ability, we designed a dimeric platform, formed by joining two nonamers through the γ‐CD cores through a bis(lithocholic acid) linker. With a view to the potential biological applications, cytotoxicity and extent of binding to human serum albumin were assessed. The properties of this dendrimeric multicarrier make it suitable for pharmaceutical and diagnostic purposes, ranging from targeted drug delivery to molecular imaging.     

Application of liquid chromatography quadrupole time-of-flight mass spectrometry to the identification of acetamiprid transformation products generated under oxidative processes in different water matrices

This work allowed the identification of major transformation products (TPs) of acetamiprid (ACTM) during Fenton process. Acetamiprid is a chloronicotinoid insecticide widely used around the world for its characteristics (high insecticidal activity, good systemic properties, suitable field stability, etc.). The degradation of the parent molecule and the identification of the main TPs were evaluated in different water matrices (demineralized water and real agro-food industrial wastewater). TPs of acetamiprid generated by Fenton experiments were monitored and identified by liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC–QTOF–MS/MS). Up to 14 TPs were characterized based on the accurate mass of the molecular ion and fragment ions obtained in both full-scan and MS/MS modes. Most of them were eliminated after 75 min of treatment time in demineralized water. However, in real agro-food industrial wastewater, most of them were eliminated at 90 min of treatment time, demonstrating the influence of the matrix composition on the studied compound degradation.