Determination of cholesterol and triglycerides in serum lipoproteins using flow field-flow fractionation coupled to gas chromatography-mass spectrometry

Asymmetric flow field flow fractionation (AsFlFFF) was combined with pyrolysis-gas chromatography mass spectrometry for a sized based fractionation and a detailed compositional study of the triglycerides and cholesterol associated with the various lipoprotein subclasses present in human serum. Serum samples were injected in the AsFlFFF instrument and fractionated with a time-delayed exponential decay cross flow program. The fractions collected after AsFlFFF elution were injected into a programmable temperature vaporizer (PTV) GC-injector, containing a fritted liner. A temperature and split-flow program for the PTV injector was optimized for the thermally assisted hydrolysis and methylation of the compounds of interest. The resulting fatty acid and cholesterol methyl esters were separated by GC and characteristic fragment ions were detected by MS. The system was optimized and calibrated with triglyceride and cholesterol standards for quantitative analysis. The possible interference by phospholipids with the quantitative results was investigated and found to be of minor importance.The concentrations and lipoprotein profiles of triglycerides and cholesterol were determined in a pooled serum sample of healthy volunteers and a serum sample of a sepsis patient. The results obtained with the GC–MS approach were compared with those of a previously developed method based on AsFlFFF with a dual enzymatic reaction detection system. A good agreement of the profiles was found, for cholesterol as well as for the triglycerides, even when the GC–MS method quantifies the fatty acids while with the enzymatic reaction method the glycerol concentrations are determined. Total cholesterol and triglyceride concentration values for the serum samples showed good agreement with the results of the standard enzymatic method as used in practice in the university hospital.     

Synthesis,spectroscopic characterization,crystal structure and antifungal activity of thiourea derivatives containing a thiazole moiety

Four novel thiourea derivatives containing a thiazole moiety were synthesized and characterized by IR, ¹H and ¹³C NMR, mass spectrometry and elemental analysis. The crystal structure of 1a was determined from single crystal X-ray diffraction data. It crystallizes in monoclinic space group P2₁/n with unit cell dimensions a = 11.7752(6) Å, b= 3.8677(2) Å, c= 27.4126(13) Å and β = 92.734(5) Å. There is a strong intramolecular hydrogen bond of the type N-H?O, with H?O distance of 2.5869(19) Å. The mass fragmentation pattern has also been discussed. The antifungal activity of the synthesized compounds was studied by broth micro-dilution method and poisoned food technique. The compounds 1b and 1c possessed a broad spectrum of antifungal activity.

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Synthesis of novel 6-substituted sulfur-containing derivatives of pyridoxine

An efficient synthesis of novel 6-substituted derivatives of pyridoxine was achieved. The reactions of various thiols with mono-, bis-, and tris(сhlorine) derivatives of 6-methyl-2,3,4-tris(hydroxymethyl)pyridin-5-ol (6-hydroxymethylpyridoxine) gave sulfur-containing derivatives of pyridoxine.     

Bright luminescent, colloidal stable silica coated CdSe/ZnS nanocomposite by an in situ, one-pot surface functionalization

In this article, a systematic study of the design and development of surface-modification schemes for silica coated nanocomposite via an in situ, one-pot way is presented. Silica coated CdSe/ZnS nanoparticles were prepared in a water-in-oil microemulsion and subsequently surface modified via addition of various organosilane reagents to the microemulsion system. The resulting functionalized composite nanoparticles were characterized by different techniques like Transmission Electron Microscopy (TEM), photoluminescence spectroscopy and zeta-potential measurements. The results demonstrate that depending on the sequence of addition of silica precursors and organosilanes the product can show bright luminescence or considerable colloidal stability. The organosilanes molecules which are used here, act both as a stabilizer of the microemulsion system (regarding the charge compensation) and as a functional group the final product on top of silica shell. Using these surface-modification process, silica coated nanoparticles can be more readily conjugated with biomolecules and used as highly luminescent, sensitive, and reproducible labels in bioanalytical applications. Most importantly such surface functionalization could pave the way for controlled multi-mixed nanoparticles encapsulation (for example magnetic and QD nanoparticles).     

Computational studies of photophysical properties of porphin, tetraphenylporphyrin and tetrabenzoporphyrin

The molecular photonics of porphyrins are studied using a combination of first-principle and semi-empirical calculations. The applicability of the approach is demonstrated by calculations on free-base porphyrin, tetraphenylporphyrin, and tetrabenzoporphyrin. The method uses excitation energies and oscillator strengths calculated at the linear-response time-dependent density functional theory (TDDFT) or the corresponding values calculated at the linear-response approximate second-order coupled-cluster (CC2) levels. The lowest singlet excitation energies obtained in the TDDFT and CC2 calculations are 0.0-0.28 eV and 0.18-0.47 eV larger than the experimental values, respectively. The excitation energies for the first triplet state calculated at the TDDFT level are in excellent agreement with experiment, whereas the corresponding CC2 values have larger deviations from experiment of 0.420.66 eV. The matrix elements of the spin-orbit and non-adiabatic coupling operators have been calculated at the semi-empirical intermediate neglect of differential overlap (INDO) level using a spectroscopic parameterization. The calculations yield rate constants for internal conversion and intersystem crossing processes as well as quantum yields for fluorescence and phosphorescence. The main mechanism for the quenching of fluorescence in tetraphenylporphyrin and tetrabenzoporphyrin is the internal conversion, whereas for free-base porphyrin both the internal conversion and the intersystem crossing processes reduce the fluorescence intensity. The phosphorescence is quenched by a fast internal conversion from the triplet to the ground state.     

Crystal structure,shape analysis and bioactivity of new LiI,NaI and MgII complexes with 1,10‐phenanthroline and 2‐(3,4‐dichlorophenyl)acetic acid

Reactions of 1,10‐phenanthroline (phen) and 2‐(3,4‐dichlorophenyl)acetic acid (dcaH) with M_n(CO₃) (M = Li^I, Na^I and Mg^II; n = 1 and 2) in MeOH yield the mononuclear lithium complex aqua[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ²N,N′)lithium(I), [Li(C₈H₅Cl₂O₂)(C₁₂H₈N₂)(H₂O)] or [Li(dca)(phen)(H₂O)] ( 1 ), the dinuclear sodium complex di‐μ‐aqua‐bis{[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ²N,N′)sodium(I)}, [Na₂(C₈H₅Cl₂O₂)₂(C₁₂H₈N₂)₂(H₂O)₂] or [Na₂(dca)₂(phen)₂(H₂O)₂] ( 2 ), and the one‐dimensional chain magnesium complex catena‐poly[[[diaqua(1,10‐phenanthroline‐κ²N,N′)magnesium]‐μ‐2‐(3,4‐dichlorophenyl)acetato‐κ²O:O′] 2‐(3,4‐dichlorophenyl)acetate monohydrate], {[Mg(C₈H₅Cl₂O₂)(C₁₂H₈N₂)(H₂O)₂](C₈H₅Cl₂O₂)·H₂O}_n or {[Mg(dca)(phen)(H₂O)₂](dca)·H₂O}_n ( 3 ). In these complexes, phen binds via an N,N′‐chelate pocket, while the deprotonated dca^? ligands coordinate either in a monodentate (in 1 and 2 ) or bidentate (in 3 ) fashion. The remaining coordination sites around the metal ions are occupied by water molecules in all three complexes. Complex 1 crystallizes in the triclinic space group P with one molecule in the asymmetric unit. The Li⁺ ion adopts a four‐coordinated distorted seesaw geometry comprising an [N₂O₂] donor set. Complex 2 crystallizes in the triclinic space group P with half a molecule in the asymmetric unit, in which the Na⁺ ion adopts a five‐coordinated distorted spherical square‐pyramidal geometry, with an [N₂O₃] donor set. Complex 3 crystallizes in the orthorhombic space group P2₁2₁2₁, with one Mg²⁺ ion, one phen ligand, two dca^? ligands and three water molecules in the asymmetric unit. Both dcaH ligands are deprotonated, however, one dca^? anion is not coordinated, whereas the second dca^? anion coordinates in a bidentate fashion bridging two Mg²⁺ ions, resulting in a one‐dimensional chain structure for 3 . The Mg²⁺ ion adopts a distorted octahedral geometry, with an [N₂O₄] donor set. Complexes 1 – 3 were evaluated against urease and α‐glucosidase enzymes for their inhibition potential and were found to be inactive.     

Synthesis and self‐assembly of diblock copolymers composed of poly(3‐hexylthiophene) and poly(fluorooctyl methacrylate) segments

Regioregular poly(3‐hexylthiophene)‐b‐poly(1H,1H‐dihydro perfluorooctyl methacrylate) (P3HT‐b‐PFOMA) diblock copolymers were synthesized by atom transfer radical polymerization of fluorooctyl methacrylate using bromoester terminated poly(3‐hexylthiophene) macroinitiators in order to investigate their morphological properties. The P3HT macroinitiator was previously prepared by chemical modification of hydroxy terminated P3HT. The block copolymers were well characterized by ¹H NMR spectroscopy and gel permeation chromatography. Transmission electron microscopy was used to investigate the nanostructured morphology of the diblock copolymers. The block copolymers are able to undergo microphase separation and self‐assemble into well‐defined and organized nanofibrillar‐like micellar morphology. The development of the morphology of P3HT‐b‐PFOMA block copolymers was investigated after annealing in solvent vapor and also in supercritical CO₂. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Gold(I)‐Catalyzed Cycloisomerizations and Alkoxycyclizations of ortho‐(Alkynyl)styrenes

Indenes and related polycyclic structures have been efficiently synthesized by gold(I)‐catalyzed cycloisomerizations of appropriate ortho‐(alkynyl)styrenes. Disubstitution at the terminal position of the olefin was demonstrated to be essential to obtain products originating from a formal 5‐endo‐dig cyclization. Interestingly, a complete switch in the selectivity of the cyclization of o‐(alkynyl)‐α‐methylstyrenes from 6‐endo to 5‐endo was observed by adding an alcohol to the reaction media. This allowed the synthesis of interesting indenes bearing an all‐carbon quaternary center at C1. Moreover, dihydrobenzo[a]fluorenes can be obtained from substrates bearing a secondary alkyl group at the β‐position of the styrene moiety by a tandem cycloisomerization/1,2‐hydride migration process. In addition, diverse polycyclic compounds were obtained by an intramolecular gold‐catalyzed alkoxycyclization of o‐(alkynyl)styrenes bearing a nucleophile in their structure. Finally, the use of a chiral gold complex allowed access to elusive chiral 1H‐indenes in good enantioselectivities.     

An Approach to the Synthesis of 7‐Amino‐6‐imino‐9‐phenyl‐6H‐benzo[c]chromene‐8‐carbonitrile Derivatives via a Three‐Component Reaction under Ultrasonic Irradiation

An efficient synthesis of 7‐amino‐6‐imino‐9‐phenyl‐6H‐benzo[c]chromene‐8‐carbonitrile derivatives 3 by a three‐component reaction of salicylaldehydes (=2‐hydroxybenzaldehydes) 1 , malononitrile (=propanedinitrile), and 2‐(1‐arylethylidene)malononitrile 2 under ultrasonic irradiation in EtOH is reported. Good yields, short reaction times, and easy purification are the main advantages of the present method. The structures were confirmed spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme 2).