Search results for "Organic chemistry"
showing 10 items of 17180 documents
Progression of Diiminopyridines: From Single Application to Catalytic Versatility
2015
Diiminopyridyl metal complexes, first characterized several decades ago, found practical application in 1998 when they were used as precatalysts in coordinative ethylene polymerization. This discovery contributed to the so-called postmetallocene revolution and triggered the large-scale experimental and theoretical research aimed at understanding diversified diiminopyridine chemistry. The results of this quest, some of which were intriguing and difficult to anticipate, are discussed and summarized in the current Review.
The SO2F2 quasi-spherical top: Correspondence between tensorial and Watson's formalisms
2006
Abstract The SO2F2 quasi-spherical top molecule with C2v symmetry is considered as a distorted spherical top deriving from the SO 4 2 − tetrahedral ion. We present here a detailed correspondence between the tensorial formalism using the Td⊃C2v reorientation and the usual Hamiltonian of Watson. We have also performed ab initio calculations in order to determine the centrifugal distorsion constants in the vibrational ground state.
Relay Catalysis: Enantioselective Synthesis of Cyclic Benzo-Fused Homoallylic Alcohols by Chiral BrOnsted Acid-Catalyzed Allylboration/Ring Closing M…
2013
Six- and seven-membered benzo-fused cyclic homoallylic alcohols can be readily synthesized by a tandem chiral BrOnsted acid-catalyzed allyl (crotyl)boration/ring closing metathesis sequence performed under orthogonal relay catalysis conditions. Excellent enantio- and diastereoselectivities are obtained in most of the cases. In addition, the parent crotylboration/RCM process is also described. The required substrates, ortho-vinylbenzaldehydes, are readily available in one step from commercially available starting materials. Both catalysts and reactants are also available from commercial suppliers. The reaction shows broad functional group compatibility and is also suitable for heteroaromatic…
Synthesis, Electrochemistry, and Photophysics of Aza-BODIPY Porphyrin Dyes
2016
International audience; The synthesis of dyad and triad aza-BODIPY-porphyrin systems in two steps starting from an aryl-substituted aza-BODIPY chromophore is described. The properties of the resulting aza-BODIPY-porphyrin conjugates have been extensively investigated by means of electrochemistry, spectroelectrochemistry, and absorption/emission spectroscopy. Fluorescence measurements have revealed a dramatic loss of luminescence intensity, mainly due to competitive energy transfer and photoinduced electron transfer involving charge separation followed by recombination.
The Missing Member of the Partially O-Alkylated Resorcinarene Family: Synthesis and Conformation of Methyl Tetramethoxy Resorcinarene
2013
An improved Lewis acid catalyzed synthesis method for methyl tetramethoxy resorcinarene is described, which produced the missing lower rim methyl derivative of this partially O-alkylated resorcinarene family. Structural characterization by means of variable temperature NMR experiments and single crystal X-ray diffraction studies furthermore revealed that the resorcinarene core adopts different conformations in the solid state and in solution. peerReviewed
Physicochemical investigation of surfactant-coated gold nanoparticles synthesized in the confined space of dry reversed micelles
2006
Abstract Gold nanoparticle/surfactant composites have been synthesized by a novel reduction reaction in the confined space of dry sodium bis(2- ethylhexyl)sulfosuccinate (AOT) or lecithin reversed micelles dispersed in n-heptane and cyclohexane, respectively. The reaction was carried out by adding an opportune amount of anhydrous hydrazine/tetrahydrofuran solution to a suspension of HAuCl4-containing dry reversed micelles dispersed in organic solvent. UV–vis investigation ascertained the formation of stable metal gold nanoparticles and the analysis of FT-IR spectra highlighted the formation of an oriented surfactant monolayer at the nanoparticle surface. Simple evaporation under vacuum of t…
Phytochemical investigation of the needles of Abies nebrodensis (Lojac.) Mattei
2019
Abies nebrodensis (Lojac.) Mattei (Pinaceae) is a species living in a very small population only in a confined area of Sicily. In this study, the dichloromethane extract of the leaves was analyzed. Apart from three already known metabolites namely dehydroabietic acid; maltol; and rheosmin, previously detected in other species of Abies, a lanostane derivative was isolated. Its chemical structure was elucidated by means of extensive spectroscopic methods.
Synthesis and biological evaluation of novel peptidomimetics as rhodesain inhibitors
2016
Novel rhodesain inhibitors were developed by combining an enantiomerically pure 3-bromoisoxazoline warhead with a 1,4-benzodiazepine scaffold as specific recognition moiety. All compounds were proven to inhibit rhodesain with Ki values in the low-micromolar range. Their activity towards rhodesain was found to be coupled to an in vitro antitrypanosomal activity, with IC50 values ranging from the mid-micromolar to a low-micromolar value for the most active rhodesain inhibitor (R,S,S)-3. All compounds showed a good selectivity against the target enzyme since all of them were proven to be poor inhibitors of human cathepsin L. Novel rhodesain inhibitors were developed by combining an enantiomeri…
Photoluminescent Detection of Human T-Lymphoblastic Cells by ZnO Nanorods.
2020
The precise detection of cancer cells currently remains a global challenge. One-dimensional (1D) semiconductor nanostructures (e.g., ZnO nanorods) have attracted attention due to their potential use in cancer biosensors. In the current study, it was demonstrated that the possibility of a photoluminescent detection of human leukemic T-cells by using a zinc oxide nanorods (ZnO NRs) platform. Monoclonal antibodies (MABs) anti-CD5 against a cluster of differentiation (CD) proteins on the pathologic cell surface have been used as a bioselective layer on the ZnO surface. The optimal concentration of the protein anti-CD5 to form an effective bioselective layer on the ZnO NRs surface was selected. …
Defying Stereotypes with Nanodiamonds: Stable Primary Diamondoid Phosphines
2016
International audience; Direct unequal C-H bond difunctionalization of phosphorylated diamantane was achieved in high yield from the corresponding phosphonates. Reduction of the functionalized phosphonates provides access to novel primary and secondary alkyl/aryl diamantane phosphines. The prepared primary diamantyl phosphines are quite air stable compared to their adamantyl and especially alkyl or aryl analogues. This finding is corroborated by comparing the singly occupied molecular orbital energy levels of the corresponding phosphine radical cations obtained by density functional theory computations.