A quinoline based bis-urea receptor for anions: a selective receptor for hydrogen sulfate

A dipodal bis-urea receptor has been synthesized from the reaction of 8-amino quinoline and 1,4-phenylene diisocyanate in dichloromethane, and the anion binding ability of the receptor has been studied using fluoride, chloride, bromide, iodide, perchlorate, nitrate, dihydrogen phosphate and hydrogen sulfate by UV-Vis titrations in DMSO. The results show that the receptor binds each of the anions with a 1:1 stoichiometry, showing high affinity and moderate selectivity for hydrogen sulfate among the anions studied. Ab initio calculations based on density functional theory (DFT) suggest that an anion (X(-)) is bonded within the cleft formed by the two arms of the receptor through two NH...X(-) and two aromatic CH...X(-) interactions. The results from solution and theoretical studies suggest that binding is predominantly influenced by hydrogen bonding interactions and the basicity of anions.     

MxDC and MxLIVE: software for data acquisition,information management and remote access to macromolecular crystallography beamlines

An integrated computer software system for on‐site and remote collection of macromolecular crystallography (MX) data at the Canadian Light Source (CLS) is described. The system consists of an integrated graphical user interface for data collection and beamline control [MX Data Collector (MxDC)] which provides experiment‐focused control of beamline devices, and a laboratory information management system [MX Laboratory Information Virtual Environment (MxLIVE)] for managing sample and experiment information through a web browser. The system allows remote planning and transmission of sample and experiment parameters to the beamline through MxLIVE, on‐site or remote data collection through MxDC guided by information from MxLIVE, and remote monitoring and download of experimental results through MxLIVE. The system is deployed and in use on both MX beamlines at the CLS which constitute the Canadian Macromolecular Crystallography Facility.     

WYE‐120318, a ring contraction product of methylnaltrexone,and structure revision of coniothyrione

A contracted ring degradation product, WYE‐120318 (compound 2), was discovered during the development phase for methylnaltrexone bromide (compound 1) drug substance. The compound was isolated by high‐performance liquid chromatography fractionation, and its structure was determined by spectroscopic data analyses. WYE‐120318 is formed from methylnaltrexone through a benzyl‐benzilic acid type rearrangement reaction to yield an α‐hydroxy‐cyclopentanecarboxylic acid substructure. The proposed structure and the formation mechanism are confirmed by the synthesis of WYE‐120318 from methylnaltrexone (compound 1). A similar benzyl‐benzilic acid type rearrangement reaction can be envisioned as the biological origin of remisporine A (compound 3), a naturally occurring cyclopentadienyl compound that autocatalytically dimerizes to remisporine B (compound 4). The structure of remisporine A was deduced from its dimer 4. Coniothyione (compound 5) can be considered as the first example of a stable natural product bearing the remisporine A skeleton. However, the regiochemistry of the chlorosubstitution in the coniothyrione structure needs to be revised to compound 6 on the basis of the nuclear magnetic resonance data and biogenesis analysis. Copyright © 2012 John Wiley & Sons, Ltd.     

Mathematical efficiency calibration methods for high quality laboratory based gamma spectrometry systems

The efficiency calibration of laboratory based gamma spectrometry systems typically involves the purchase or construction of calibration samples that are supposed to represent the geometries of the unknown samples to be measured. For complete and correct calibrations, these sample containers must span the operational range of the system, which at times can include difficult configurations of size, density, matrix, and source distribution. The efficiency calibration of a system is dependent not only on the detector, but on the radiation attenuation factors in the detector–source configuration, and therefore is invalid unless all parameters of the sample assay condition are identical to the calibration condition. An alternative to source-based calibrations is to mathematically model the efficiency response of a given detector–sample configuration. In this approach, the measurement system is calibrated using physically accurate models whose parameters can generally be easily measured. Using modeled efficiencies, systems can be quickly adapted to changing sample containers and detector configurations. This paper explores the advantages of using mathematically computed efficiencies in place of traditional source-based measured efficiencies for laboratory samples, focusing specifically on the possibility of sample optimization for a given detector, uncertainty estimation, and cascade summing corrections.     

General Synthesis of 1‐Substituted 2‐Methylbenzimidazoles from Ketones and 2‐Aminoacetanilide

A novel method for preparation of 1‐substituted benzimidazoles via reductive amination of ketones with N‐differentiated 1,2‐diaminobenzenes is described. The method appears to be general in application to acyclic and cyclic ketones, as well as heteroatom‐substituted cyclic ketones.     

Über die Einwirkung der stillen elektrischen Entladung auf Chlor

Ohne ZusammenfassungHerr B. Larsen hat mich bei der Ausführung der Versuche in dankenswerter Weise unterstützt.