Modified Clerodanes from the Essential Oil of Leaves.

(L.) Jacq from Reunion Island (Indian Ocean) was investigated for its leaf essential oil composition. The plant was extracted by hydrodistillation and its essential oil analysed by gas chromatography coupled to mass spectrometry.

Antimalarial Activities of Alkyl Cyclohexenone Derivatives Isolated from the Leaves of Poupartia borbonica.

Bioactivity-guided fractionation of the ethyl acetate extract of the leaves of Poupartia borbonica led to the isolation of three new alkyl cyclohexenone derivatives 1-3, and named Poupartone A-C. The structures of the new compounds were elucidated by 1D and 2D NMR spectroscopic data analysis and MS, whereas calculated and experimental ECD spectra were used to define the absolute configurations. These compounds were active against 3D7 and W2 Plasmodium falciparum strains with IC values between 0.

Unguiculin A and Ptilomycalins E-H, Antimalarial Guanidine Alkaloids from the Marine Sponge Monanchora unguiculata.

Chemical study of the CHCl-MeOH (1:1) extract from the sponge Monanchora unguiculata collected in Madagascar highlighted five new compounds, one acyclic guanidine alkaloid, unguiculin A (1) and four pentacyclic alkaloids, ptilomycalins E-H (2-5), along with four known compounds: crambescidin 800 (6) and crambescidin 359 (7), crambescidic acid (8), and fromiamycalin (9). Their structures were elucidated by 1D and 2D NMR spectra and HRESIMS data. All compounds were evaluated for their cytotoxicity against KB cells and their antiplasmodial activity.

Contribution of trans-aconitic acid to DPPH scavenging ability in different media.

The antioxidant properties of trans-aconitic acid (TAA) alone or in the presence of usual antioxidants were assessed by DPPH assay. The IC50 value equal to 70mM was very high compared to usual antioxidants (vitamin C and trolox). A joint experimental/theoretical study suggested that hydrogen atom abstraction in TAA by DPPH was located on -CH2- methylene bridge because the corresponding radical was more stabilized than COO(·) and CC(·) radicals.

Can quantum-mechanical calculations yield reasonable estimates of hydrogen-bonding acceptor strength? The case of hydrogen-bonded complexes of methanol.

The thermodynamics and some vibrational properties of hydrogen-bonded complexes of methanol with 23 hydrogen-bond acceptors (HBAs) have been determined in CCl(4) by FTIR spectrometry. The experimental sample contains carbon, nitrogen, oxygen, sulfur, fluorine, and chlorine organic bases and covers an energetic range of 13 kJ mol(-1) in the basicity scale (-ΔG), 22 kJ mol(-1) in the affinity scale (-ΔH), and 400 cm(-1) in the spectroscopic scale (Δν((OH))) (from benzene to trimethylphosphane oxide and amines). The experimental results in CCl(4) are compared to those computed in the gas phase at various levels of theory.

Molar mass, radius of gyration and second virial coefficient from new static light scattering equations for dilute solutions: application to 21 (macro)molecules.

New static light scattering (SLS) equations for dilute binary solutions are derived. Contrarily to the usual SLS equations [Carr-Zimm (CZ)], the new equations have no need for the experimental absolute Rayleigh ratio of a reference liquid and solely rely on the ratio of scattered intensities of solutions and solvent. The new equations, which are based on polarizability equations, take into account the usual refractive index increment partial differential n/partial differential rho(2) complemented by the solvent specific polarizability and a term proportional to the slope of the solution density rho versus the solute mass concentration rho(2) (density increment).

Comparison of Proutière and Carr-Zimm theories for static light-scattering molecular weight determination: application to surfactants in solution.

Proutière's theory of molecular weight (M) determination by Rayleigh scattering has been tested on surfactants in solution, and it has been compared to the classical Carr-Zimm (CZ) method. Both methods make use of time-averaged scattering intensity, refractive index, and density measurements. Monoethers of poly(ethylene glycol) samples have been studied in the range 0.

B3LYP and MP2 calculations of the enthalpies of hydrogen-bonded complexes of methanol with neutral bases and anions: comparison with experimental data.

To perfect a method for building a theoretical hydrogen-bond basicity scale, the enthalpy of hydrogen bonding between methanol and thirteen neutral and anionic bases (MeOH, MeNH2, Me2NH, Et2NH, Me3N, Et3N, Br-, CN-, SH-, Cl-, HCOO-, MeO-, F-) was calculated by DFT and ab initio methods. The theoretical results were compared to selected experimental ones. It appears that B3LYP/6-31+G(d,p) calculations are satisfactory for optimizing the geometry of complexes and giving a general order of basicity.

Synthesis of oligothiophene-bridged bisporphyrins and study of the linkage dependence of the electronic coupling.

A set of twelve porphyrin dimers has been prepared to give information on how the type of connectivity between a porphyrin core and a bridge can influence the interporphyrin electronic interaction. The new porphyrin systems are substituted directly at the meso position with an oligothiophene chain tethered either with a single C-C sigma bond, a trans ethylenyl group, or a acetylenyl group. The compounds are easily obtained by palladium-catalyzed cross-coupling reactions (Stille, Heck, and Sonogashira) between 5-iodo-10,15,20-(3,5-ditert-butylphenyl)porphyrin and the appropriate oligothiophene derivative.

Bridged Dithienylethylenes as Precursors of Small Bandgap Electrogenerated Conjugated Polymers.

Bridged dithienylethylenes (DTEs) bearing solubilizing alkyl chains at various positions (2-5) have been synthesized by McMurry dimerization of cyclopenta[b]thiophen-6-ones. In order to introduce alkyl substituents at different positions of the DTE molecule, the precursor ketones have been prepared by different strategies based on a combination of Mannich or Wittig-Horner reaction and Friedel-Craft intramolecular cyclization. The position and the length of the alkyl substituents exert a strong effect on the ability of the precursor to undergo electrochemical polymerization.