Synthesis of a fluorous ligand and its application for asymmetric addition of dimethylzinc to aldehydes

A new fluorous ligand was synthesized from the acetonide of dimethyl tartarate, which showed excellent asymmetric induction on the addition of dimethylzinc to aldehydes. This ligand will be useful for synthesis of bioactive compounds with a methyl carbinol moiety. It could be recycled without using a fluorous solvent or a fluorous column.     

Characterization of in‐plane structures of vapor deposited thin‐films of distyryl‐oligothiophenes by grazing incidence x‐ray diffractometry

The in‐plane structures of vapor deposited ultrathin films of distyryl‐oligothiophenes (DS‐2T) on SiO₂ substrate were characterized by grazing incidence x‐ray diffractometry (GIXD). Two polymorphs, low‐temperature and high‐temperature phases, were identified, and the two dimensional unit cell parameters were determined for each polymorph. The polymorphism depends on substrate temperature and film thickness. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

An Operator Method of the Theory of Optical Coherence and Radiometry

This paper presents a quantum mechanical formalism of the classical coherence theory, within which the generalized radiance function defined in the time domain is regarded as a phase space representative of a time-dependent correlation operator of a polychromatic field. The theory deals with both stationary and nonstationary fields and, for a stationary field, provides a new operator formalism of the usual theory of optical coherence developed in the space-frequency domain. New results include an operator representation of the mutual coherence function, an operator version of the Wiener-Khintchine theorem, and an operator theorem that projects the correlation operator of a polychromatic field onto a particular spectral component. As illustrative examples, the previous formulas regarding the relationship between temporal coherence and spatial coherence, and the relationship between spectral properties and coherence properties are derived from the new operator formulas. The correspondence of the present formalism to the usual formalism using Dirac notation to describe the propagation of a stationary, partially coherent, quasi-monochromatic field is also considered.     

Prediction of Molecular Properties Using Molecular Topographic Map

Prediction of molecular properties plays a critical role towards rational drug design. In this study, the Molecular Topographic Map (MTM) is proposed, which is a two-dimensional (2D) map that can be used to represent a molecule. An MTM is generated from the atomic features set of a molecule using generative topographic mapping and is then used as input data for analyzing structure-property/activity relationships. In the visualization and classification of 20 amino acids, differences of the amino acids can be visually confirmed from and revealed by hierarchical clustering with a similarity matrix of their MTMs. The prediction of molecular properties was performed on the basis of convolutional neural networks using MTMs as input data. The performance of the predictive models using MTM was found to be equal to or better than that using Morgan fingerprint or MACCS keys. Furthermore, data augmentation of MTMs using mixup has improved the prediction performance. Since molecules converted to MTMs can be treated like 2D images, they can be easily used with existing neural networks for image recognition and related technologies. MTM can be effectively utilized to predict molecular properties of small molecules to aid drug discovery research.     

Alamethicin-leucine zipper hybrid peptide: a prototype for the design of artificial receptors and ion channels.

In this report, we describe a novel concept of extramembrane control of channel peptide assembly and the eventual channel current modulation. Alamethicin is a peptide antibiotic, which usually forms ion channels in various association states. By introducing an extramembrane leucine zipper segment (Alm-LeuZ), the association number of alamethicin was effectively controlled to produce a single predominant channel open state. The assembly was estimated to be a tetramer, by comparison of the channel conductance with that of the template-assembled Alm-LeuZ tetramer, which was prepared by the conjugation of a maleimide-functionalized peptide template with cysteine-derivatized Alm-LeuZ segments. Employment of an extramembrane segment of a random conformation provided higher levels of channel conductance. The result exemplified the possibility of channel current control by a conformational switch of the extramembrane segments.     

Enantioselective alkynylation of aldehydes with chiral β-imino α-perfluoroalkylpropanol derivatives

Chiral β-imino α-perfluoroalkylpropanol derivatives 1 were prepared by condensation of (2S,3S)-2-amino-3-perfluorooctyl-1-phenylpropan-3-ol 2 and aldehydes. Among them, (2S,3S)-1d prepared from 2 and salicylaldehyde catalyzed the asymmetric alkynylation of aldehydes using alkynylzincs to afford the product in up to 81% ee.     

Synthesis of fluorine analogs of protoporphyrin potentially useful for diagnosis and therapy of cancer. IV. Synthesis of (trifluorovinyl)vinyl- and (1-chloro-2,2-difluorovinyl)vinyldeuteroporphyrins.

Trifluoro or chlorodifluoro analogs of protoporphyrin, the compounds in the title, were synthesized for use in the diagnosis and therapy of cancer. 3- Or 8-acetyldeuteroporphyrin dimethyl esters (2 and 3) were iodinated with iodine in the presence of potassium carbonate to the corresponding iodo compounds (5 and 6). The iodo compounds (5 and 6) were treated with bis(trifluorovinyl)zinc in the presence of tetrakis(triphenylphosphine)-palladium to give trifluorovinyl derivatives (7 and 8) in good yields. Reduction of the acetyl group of 7 and 8 with sodium borohydride afforded the corresponding hydroxyethyl derivatives (9 and 10). Compounds (9 and 10) were dehydrated with methanesulfonyl chloride and triethylamine to give (trifluorovinyl)vinyldeuteroporphyrin dimethyl esters (11 and 12). Treatment of 5 and 6 with bis(1-chloro-2,2-difluorovinyl)zinc in the presence of tetrakis(triphenylphosphine)palladium, followed by similar reactions as above gave (1-chloro-2,2-difluorovinyl)-vinyldeuteroporphyrin dimethyl esters (17 and 18).     

Noncatalytic high temperature extraction-nonaqueous titrimetric microdetermination of oxygen in organic compounds

Summary Oxygen in various organic compounds was directly converted to carbon monoxide by decomposing a sample in a graphite crucible at higher than 1800° C. The decomposition products containing the monoxide were purified with soda-asbestos and heated copper wire using argon as a carrier gas. Then the monoxide was oxidized with heated copper(II) oxide. Carbon dioxide produced was absorbed with dimethylformamide containing 2-aminoethanol, and was titrated with a standard solution of tetra-n-butylammonium hydroxide in benzene plus some methanol using thymolphthalein as an indicator.Various types of oxygen in many organic compounds were converted to carbon monoxide stoichiometrically by the above decomposition process. Down to 2g of oxygen was determined with 0.3g error (standard deviation) without any calibrations. Interferences of nitrogen, sulphur and halogene (including fluorine) were removed thoroughly. The method was also applicable to an organoiron compound.

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Unkatalysierte Hochtemperatur-Extraktion und Titration in nicht wäßriger Phase zur Mikrobestimmung von Sauerstoff in organischen Verbindungen

Zusammenfassung Der Sauerstoff verschiedener organischer Verbindungen läßt sich unmittelbar in Kohlenmonoxid umsetzen, indem man die Probe in einem Graphittiegel höher als 1800° C erhitzt. Die Zersetzungsprodukte mit dem Monoxid werden mit Natronasbest und erhitztem Kupferdraht gereinigt, wobei man Argon als Trägergas verwendet. Dann wird das Monoxid über Kupfer(II)oxid oxydiert. Das Kohlendioxid wird in einer Lösung von 2-Aminoethanol in Dimethylformamid absorbiert und mit einer Standardlösung von Tetra-n-butylammoniumhydroxid in Benzol und etwas Methanol titriert, wobei Thymolphthalein als Indikator dient. — Verschiedenartig gebundener Sauerstoff in vielerlei organischen Verbindungen läßt sich durch das angegebene Zersetzungsverfahren stöchiometrisch in Kohlenmonoxid umsetzen. Bis auf 2g Sauerstoff wurden mit einer Standardabweichung von 0,3g ohne vorhergehende Eichung bestimmt. Störungen durch Stickstoff, Schwefel und Halogene (einschließlich Fluor) lassen sich vollständig vermeiden. Das Verfahren eignet sich auch für organische Eisenverbindungen.

     

Chaotic wavelength division multiplexing for optical communication

We demonstrate wavelength division multiplexing with chaotic subcarriers in two pairs of one-way-coupled Nd:YVO4 microchip lasers. Two individual digital messages are encoded on two chaotic carriers with different wavelengths in two transmitters by the chaotic masking method, and the mixed signals are sent to two receivers. Dual synchronization of chaos is used to obtain the original chaotic waveforms in the receivers. Two messages are decoded by filtering the difference of the laser outputs between the transmitter and the receiver by use of a low-pass filter for each pair of lasers. The message recovery can be achieved more easily when messages with small amplitude and low frequency are used.