Characterization Of Dimers Research Articles

Synthesis and characterization of a fluorescent steroid dimer linked through C-19 by a 1,4-Bis(phenylethynyl)phenylene fragment

The synthesis and characterization of a dimer in which two nuclei of 3β-acetoxy-19-hydroxyandrost-5-en-17-one are linked by the fluorescent 1,4-bis(phenylethynyl)phenylene bridge attached to the oxygenated functions at positions C-19 of each steroid fragment is described. The compound was obtained in five steps and 23 % overall yield and showed a strong blue emission with a quantum yield of 0.66.

Synthesis and spectroscopic characterization of dimer, mono- and bi-nuclear copper complexes of 2-[α-(acetyloxime)ethylidenehydrazino]-4,6-dimethylquinoline

Synthesis and spectroscopic characterization of dimer, mono- and bi-nuclear copper complexes of 2-[α-(acetyloxime)ethylidenehydrazino]-4,6-dimethylquinoline

다이머산계 폴리아미드의 합성 및 특성에 관한 연구

다이머산계 폴리아미드의 합성 및 특성에 관한 연구

Oligomerization Reactions of Bis(ethynyl)tetraphenylporphyrin Derivatives by Glaser–Hay Coupling Reaction: Isolation and Characterization of Dimer, Trimer, and Tetramer

The Glaser–Hay coupling reaction of a tetraphenylporphyrin derivative having two acetylenes in the quasi-trans positions was carried out. Although this oxidative coupling reaction has high reactivity and produces various butadiynylene oligomers, the degree of oligo­merization was low. A large substrate and/or product might decrease the frequency factor of the Arrhenius equation and the resultant rate constant. This finding is in agreement with that of the one-pot synthesis of structurally well-defined porphyrin oligomers, such as trimers and tetramers, which are used frequently in the field of advanced materials.

Characterization of Dimers of Hydroquinone Glucosides Produced by Peroxidase-Catalyzed Polymerization

4'-Hydroxyphenyl alpha-glucoside and 4'-hydroxyphenyl beta-glucoside were polymerized with horseradish peroxidase. The isolated dimers were found to have linkages at C3' of the hydroxyphenyl moieties and proved to be fluorescent. Low accumulation of oligomers was attributed to increasing electrochemical reactivity with polymerization degrees, which were expected from the levels of highest occupied molecular orbital.

Novel synthesis and characterization of five isomers of (C(70))(2) fullerene dimers.

The synthesis and characterization of dimers and polymers, wherein two or more cages are linked, represent an important frontier in the chemistry of fullerene derivatives. A simple and novel method that requires no special apparatus has been developed for the dimerization of [70]fullerene to (C70)2. Upon grinding [70]fullerene in a mortar and pestle in the presence of K2CO3, five structural isomers of (C70)2 have been produced. These isomers are separated from one another via high performance liquid chromatography and are characterized by 13C NMR, UV-vis-NIR absorption and mass spectroscopy.

Synthesis of dimer and oligomers from (R)‐methyl hydnocarpate

AbstractWe report synthesis and characterization of dimer and oligomer acids from chaulmoogra oil. (R)‐Methyl hydnocarpate (methyl ester of the major fatty acid component of chaulmoogra oil) was brominated to give threo‐2,3‐dibromocyclopentane‐1‐methyl undecanoate. Formation of two diastereoisomers, viz., threo‐2(R),3(R)‐dibromocyclopentane‐1(R)‐methyl undecanoate and threo‐2(S),3(S)‐dibromocyclopentane‐(R)‐1‐methyl undecanoate, was observed. Dehydrobromination of bromo derivatives using alcoholic KOH gave a cyclopentadiene derivative as intermediate, which underwent Diels‐Alder reaction to give dimer and oligomer fatty acids. The products were characterized by ultraviolet, direct exposure probe‐mass spectroscopy, 1H nuclear magnetic resonance (NMR), and 13C NMR spectroscopic techniques.

ChemInform Abstract: Synthesis and Characterization of Dimers, Trimers, and Tetramers of 3, 6‐Dimethylthieno(3,2‐b)thiophene and 3,6‐Dimethylselenolo(3,2‐b) selenophene.

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Synthesis and characterization of dimers, trimers, and tetramers of 3,6-Dimethylthieno[3,2- b]thiophene and 3,6-Dimethylselenolo[3,2- b]selenophene

3,6-Dimethylthieno[3,2- b]thiophene ( 1a) and 3,6-dimethylselenolo[3,2- b]selenophene ( 1b) have recently become readily obtainable. Starting from these compounds, their dimers, trimers, and tetramers, in which each thienothiophene unit and selenoloselenophene unit were regularly connected at their α-position, were satisfactorily synthesized and characterized by UV/Vis spectral and CV oxidation potentials data. X-Ray single crystal structure analysis of the dimer of 1b revealed that two selenoloselenophene units are twisted with a large dibedral angle of 69.5° with an s-cis structure.

Synthesis of oxo- and methylene-bridged C60 dimers, the first well-characterized species containing fullerene-fullerene bonds.

The preparation and characterization of dimers and polymers, wherein two or more cages are directly linked, represents an important frontier in the chemistry of fullerene derivatives. We report the preparation of novel oxo- and methylene-bridged C{sub 60} dimers, the first well-characterized compounds containing fullerene-fullerene bonds. 22 refs., 3 figs.

Native mitochondrial creatine kinase forms octameric structures. II. Characterization of dimers and octamers by ultracentrifugation, direct mass measurements by scanning transmission electron microscopy, and image analysis of single mitochondrial creatine kinase octamers.

Electron micrographs of negatively stained and metal-shadowed mitochondrial creatine kinase (Mi-CK) molecules purified as described by Schlegel et al. (Schlegel, J., Zurbriggen, B., Wegmann, E., Wyss, M., Eppenberger, H. M., and Wallimann, T. (1988) J. Biol Chem. 263, 16942-16953) revealed a homogeneous population (greater than or equal to 95%) of distinctly sized square-shaped, octameric particles with a side length of 10 nm that frequently exhibited a pronounced 4-fold axis of symmetry. The cube-like molecules consist of four dimers that are arranged around a stain-accumulating central cavity of 2.5-3 nm in diameter. This interpretation is supported by single particle averaging including correlation analysis by computer. Upon prolonged storage or high dilution, the cube-like octamers tended to dissociate into "banana-shaped" dimers. Sedimentation velocity and sedimentation equilibrium experiments yielded an s value of 12.8-13.5 S and an Mr of 328,000 +/- 25,000 for the octameric cubes. An s value of 5.0 S and a Mr of 83,000 +/- 8,000 was found under conditions which revealed banana-shaped dimers. These dimers proved to be very stable, as their dissociation into monomers of 45 kDa (s value = 2.0 S) required 6 M guanidine HCl. Thus, the oligomeric structures observed in the electron microscope are identified as Mi-CK dimers (banana-shaped structures) and cubical Mi-CK octamers assembled from four Mi-CK dimers. The octameric nature of native Mi-CK and the formation of Mi-CK dimers were confirmed by direct mass measurements of individual molecules by scanning transmission electron microscopy yielding a molecular mass of 340 +/- 55 kDa for the octamer and 89 +/- 27 kDa for the dimer. A structural model of Mi-CK octamers and the possible interaction with ATP/ADP-translocator molecules as well as with the outer mitochondrial membrane is proposed. The implications with respect to the physiological function of Mi-CK as an energy-channeling molecule at the producing side of the phosphoryl creatine shuttle are discussed.