Binary systems of discotic liquid crystalline semiconductors toward solution-processing thin film devices

SPIE OPTO, 2012, San Francisco, California, United StatesY. Shimizu, Y. Matsuda, F. Nekelson, Y. Miyake, H. Yoshida, A. Fujii, and M. Ozaki "Binary systems of discotic liquid crystalline semiconductors toward solution-processing thin film devices", Proc. SPIE 8279, Emerging Liquid Crystal Technologies VII, 82790G (10 February 2012). DOI: https://doi.org/10.1117/12.91354

A capping methodology for the synthesis of lower mu-oxo-phthalocyaninato silicon oligomers

Background: With the advent of high-throughput targeted metabolic profiling techniques, the question of how to interpret and analyze the resulting vast amount of data becomes more and more important. In this work we address the reconstruction of metabolic reactions from cross-sectional metabolomics data, that is without the requirement for time-resolved measurements or specific system perturbations. Previous studies in this area mainly focused on Pearson correlation coefficients, which however are generally incapable of distinguishing between direct and indirect metabolic interactions. Results: In our new approach we propose the application of a Gaussian graphical model (GGM), an undirected probabilistic graphical model estimating the conditional dependence between variables. GGMs are based on partial correlation coefficients, that is pairwise Pearson correlation coefficients conditioned against the correlation with all other metabolites. We first demonstrate the general validity of the method and its advantages over regular correlation networks with computer-simulated reaction systems. Then we estimate a GGM on data from a large human population cohort, covering 1020 fasting blood serum samples with 151 quantified metabolites. The GGM is much sparser than the correlation network, shows a modular structure with respect to metabolite classes, and is stable to the choice of samples in the data set. On the example of human fatty acid metabolism, we demonstrate for the first time that high partial correlation coefficients generally correspond to known metabolic reactions. This feature is evaluated both manually by investigating specific pairs of high-scoring metabolites, and then systematically on a literature-curated model of fatty acid synthesis and degradation. Our method detects many known reactions along with possibly novel pathway interactions, representing candidates for further experimental examination. Conclusions: In summary, we demonstrate strong signatures of intracellular pathways in blood serum data, and provide a valuable tool for the unbiased reconstruction of metabolic reactions from large-scale metabolomics data sets

Stepwise syntheses of complex μ-oxo-linked heterochromophore arrays containing phthalocyanine, porphyrin and subphthalocyanine ligands

The article reviews the exploitation of the serendipitous discovery that dihydroxysilicon 1,4,8,11,15,18,22,25-octakis(hexyl)phthalocyanine 1 reacts at one face only to form a µ-oxo linked bond to dichlorosilicon phthalocyanine. Reaction of 1 with dihydroxysilicon octaethylporphyrin led to an unstable µ-oxo linked Pc-O-Pn heteroligand dyad that could not be isolated. However, reaction with dihydroxygermanium octaethylporphyrin gave a stable dyad that showed substantial broad band absorption attributable to exciton effects. A small amount of the µ-oxo linked homo dyad formed by self-condensation of dihydroxygermanium octaethylporphyrin was detected by MALDI-TOF mass spectrometry but was not isolated. Reaction of 1 with chloroboron subphthalocyanine afforded the stable Pc-O-SubPc heterodyad as the main product and the SubPc-O-Pc-O-SubPc triad as a minor side product. Both gave absorption spectra that showed the main features of the ligands present, implying limited exciton coupling. A further reaction of 1 with axial-hydroxy, axial-methyl silicon phthalocyanine provided a key Pc-O-Pc' dyad that proved to be an ideal intermediate for developing a synthetic strategy to access a series of hetero-metalloid/hetero-ligand Pc-O-Pc'-O-Pn triads. X-ray structural data for examples of these arrays are discussed. A feature of the triad compounds is their very broad band absorption spectra that extends from the UV through the visible region to near IR wavelengths

A Capping Methodology for the Synthesis of Lower μ-Oxo-phthalocyaninato Silicon Oligomers

A mixed condensation of a substituted and unsubstituted silicon phthalocyanine monomer, in which the former serves as a “cap” to a growing oligomeric chain, provides unprecedented access to a mixed dimer, trimers, and a tetramer. An important element of product control can be achieved by changing the ratio of the precursor monomers

Tunable grafting of functional polymers onto carbon nanotubes using diazonium chemistry in aqueous media

International audienceIn this work, we present an efficient grafting of functional polymers onto multi-walled carbon nanotubes using a simple and versatile chemical process carried out in open air and in aqueous media. The method involves in situ reduction of substituted (-COOH, -NH(2), -F center dot center dot center dot)aryl diazonium salts which yields poly (phenylene)-like coatings covalently grafted on the nanotube surface. Tuning the concentration of in situ generated diazonium was found to be an efficient way to control the total amount of grafted polymer. Functionalized nanotube samples were studied by complementary techniques such as electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy