Synthesis of pyrrolidinoindolines from 2-(2-oxo-3-indolyl)acetates: scope and limitations

A series of 1,3a,8-alkylpyrrolidinoindolines have been synthesized. The scope and limitations of the alkylation of starting methyl oxindol-3-acetates are explored employing electron-rich and electron-poor alkylating agents. Hydrolysis and reductive lactonization of the resulting carboxylic gamma-oxindolic acid derivatives proceeds with good yields to afford 2-oxofuroindolines providing ready access to the pyrrolidinoindoline derivatives.     

Fatty acids determination in Bronte pistachios by gas chromatographic method

A gas chromatographic with flame ionization detector (GC-MS FID) method for the identification and quantification of fatty acids based on the extraction of lipids and derivatisation of free acids to form methyl esters was developed and validated. The proposed method was evaluated to a number of standard FAs, and Bronte pistachios samples were used for that purpose and to demonstrate the applicability of the proposed method. In this regard, repeatability, mean and standard deviation of the analytical procedure were calculated. The results obtained have demonstrated oleic acid as the main component of Bronte pistachios (72.2%) followed by linoleic acid (13.4%) and showed some differences in composition with respect to Tunisian, Turkish and Iranian pistachios.     

Determination of fluoroquinolone antibiotics in surface waters from Mondego River by high performance liquid chromatography using a monolithic column

A novel LC-fluorescence detection method based on the use of a monolithic column for the determination of norfloxacin, ciprofloxacin, and enrofloxacin antibiotic residues in environmental waters was developed. Fluoroquinolones (FQs) were isocratically eluted using a mobile phase consisting of 0.025 M phosphoric acid solution at pH 3.0 with tetrabutylammonium and methanol (960:40, v/v) through a Chromolith Performance RP-18e column (100x4.6 mm) at a flow rate of 2.5 mL/min and detected at excitation and emission wavelengths of 278 and 450 nm, respectively. After acidification and addition of EDTA, water samples were extracted using an Oasis HLB cartridge. Linearity was evaluated in the range of 0.05 to 1 microg/mL and correlation coefficients of 0.9945 for norfloxacin, 0.9974 for ciprofloxacin, and 0.9982 for enrofloxacin were found. The limit of quantification was 25 ng/L for the three FQs. The recovery of FQs spiked into river water samples at 25, 50, and 100 ng/L fortification levels ranged from 76.5 to 91.0% for norfloxacin, 78.5 to 97.2% for ciprofloxacin, and 79.4 to 93.6% for enrofloxacin. This method was successfully applied to the analysis of water samples from the Mondego River, and ciprofloxacin and enrofloxacin residues were detected in eight water samples.     

Tuning the Surface of Nanoparticles: Impact of Poly(2‐ethyl‐2‐oxazoline) on Protein Adsorption in Serum and Cellular Uptake

Due to the adsorption of biomolecules, the control of the biodistribution of nanoparticles is still one of the major challenges of nanomedicine. Poly(2‐ethyl‐2‐oxazoline) (PEtOx) for surface modification of nanoparticles is applied and both protein adsorption and cellular uptake of PEtOxylated nanoparticles versus nanoparticles coated with poly(ethylene glycol) (PEG) and non‐coated positively and negatively charged nanoparticles are compared. Therefore, fluorescent poly(organosiloxane) nanoparticles of 15 nm radius are synthesized, which are used as a scaffold for surface modification in a grafting onto approach. With multi‐angle dynamic light scattering, asymmetrical flow field‐flow fractionation, gel electrophoresis, and liquid chromatography‐mass spectrometry, it is demonstrated that protein adsorption on PEtOxylated nanoparticles is extremely low, similar as on PEGylated nanoparticles. Moreover, quantitative microscopy reveals that PEtOxylation significantly reduces the non‐specific cellular uptake, particularly by macrophage‐like cells. Collectively, studies demonstrate that PEtOx is a very effective alternative to PEG for stealth modification of the surface of nanoparticles.

     

Kinetic approach to mild steel corrosion

Summary The rate of steel corrosion in hydrochloric acid solutions in the absence and in the presence of inhibitors is studied. It is found that the process dynamics is described by an exponential kinetic equation of self-accelerating reactions in the absence of inhibitor and by an equation of a zero order in its presence.     

Synthesis,Crystal Structure and Hirshfeld Surfaces of the N-(bis(benzylamino)phosphoryl)-4-Methylbenzenesulfonamide Polymeric tetrakis-Complex {Na[Yb(L)4(iPrOH)]}n

Lanthanide containing polymer chain of title compound {Na[Yb(L)₄(ⁱPrOH)]}_n is formed by alternating complex anions and sodium cations. The anion is composed by four deprotonated bidentate chelate ligands of sulfonylamidophosphate type N-(bis(benzylamino)phosphoryl)-4-methylbenzenesulfonamide (L^?) coordinated to the Yb(III) ion via O atoms belonging to the sulfonyl and phosphoryl groups. The coordination polyhedron of the ytterbium has a slightly distorted triangular dodecahedron conformation, TDD-8, D_2d. The Na⁺ cation is coordinated by four sulfonyl O atoms, the NaO₄ polyhedra shape is intermediate between axially vacant trigonal bipyramid C_3v and tetrahedron T_d. Single-crystal X-ray diffraction studies show that one 2-propanol molecule is hydrogen-bonded to the sulphonyl oxygen of one of the chelate ligands. Also the extensive network of hydrogen bonding interactions between the aromatic rings both in the structural unit and between the polymer chains were detected. They were investigated by the analysis of Hirshfeld surfaces and fingerprint plots. The correlations between structure parameters obtained and the physico-chemical properties of the {Na[Yb(L)₄(ⁱPrOH)]}_n were investigated.

Graphic Abstract

New tetrakis-complex {Na[Yb(L)₄(ⁱPrOH)]}_n was synthesized and characterized by X-ray crystallography. Structural packaging characteristics were investigated by the analysis of Hirshfeld surfaces.

     

Synthesis and polymerization of amphiphilic methacrylates containing permanent dipole azobenzene chromophores

New amphiphilic photochromic methacrylates with the structures of 4‐[ω‐methacryloyloxyoligo(ethyleneglycol)]‐4′‐cyanoazobenzene (MEn) and 4‐methacryloyloxy‐4′‐{2‐cyano‐3‐oxy‐3‐[ω‐methoxyoligo(ethyleneglycol)]prop‐1‐en‐1‐yl}azobenzene (MEnMe) and oligo(oxyethylene) segments of different lengths were synthesized. These methacrylates were characterized by the presence of permanent dipole azobenzene chromophores and hydrophilic oligo (oxyethylene) segments. The methacrylates were obtained with six‐step and five‐step synthetic sequences, respectively, in 12–47% overall yields. The radical polymerization of the MEn monomers afforded a 50% yield of the corresponding polymers as orange solids with a number‐average molecular weight of about 40 kD. No solid polymer was obtained from the radical polymerization of the MEnME compounds. Two‐dimensional NMR spectra allowed the unequivocal assignment of the NMR signals and demonstrated a significant contribution of internal charge transfer to the electronic distribution of the azobenzene chromophore. Relaxation time measurements confirmed that the flexible polyether segment effectively decoupled photochromic groups from the polymer backbone. Optical microscopy, differential scanning calorimetry analysis, and X‐ray diffraction data demonstrated the presence of interdigitated smectic mesophases. The stability of mesophases showed a significant dependence on the chemical structure of the analyzed compounds. The glass‐transition temperatures of the polymers were rather low because of the plasticizing effect of the spacers. The monomers and polymers were used for the deposition of Langmuir films and Langmuir–Blodgett–Kuhn multilayers. A strong influence of the macromolecular structure on the film properties was observed. The photoresponsive properties of monomers and polymers were investigated with irradiation at different wavelengths. Isomerization kinetics were independent of both molecular weight and spacer length. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2957–2977, 2001     

Automated,Accelerated Nanoscale Synthesis of Iminopyrrolidines

Miniaturization and acceleration of synthetic chemistry is an emerging area in pharmaceutical, agrochemical, and materials research and development. Herein, we describe the synthesis of iminopyrrolidine‐2‐carboxylic acid derivatives using chiral glutamine, oxo components, and isocyanide building blocks in an unprecedented Ugi‐3‐component reaction. We used I‐DOT, a positive‐pressure‐based low‐volume and non‐contact dispensing technology to prepare more than 1000 different derivatives in a fully automated fashion. In general, the reaction is stereoselective, proceeds in good yields, and tolerates a wide variety of functional groups. We exemplify a pipeline of fast and efficient nanomole‐scale scouting to millimole‐scale synthesis for the discovery of a useful novel reaction with great scope.