RESUMEN
The highly toxic anticoagulant rodenticide brodifacoum is an organic compound that has two diastereomeric forms. In this paper, we consider the hypothesis that the relative population of the diastereomers is a characteristic of forensic value for the association or source attribution of specimens of brodifacoum. In general, the stereoisomer distribution in an organic compound depends on the reagents, conditions, and methods used for synthesis and purification, and may vary over time due to differential stabilities of the stereoisomers. The stereoisomer distribution may thus serve as an identifier of the production methods and history of samples and provide a basis for comparing recovered specimens. We refer to this novel approach for signature detection as stereoisomer distribution analysis or SDA. If the stereoisomers are diastereomers, quantitative determination of the diastereomer ratio in a specimen can be performed by a number of techniques, notably gas or liquid chromatography or nuclear magnetic resonance (NMR) spectroscopy. This paper describes an NMR spectroscopic analysis of ten commercial technical grade brodifacoum samples from distinct batches originating from three different sources. The results reveal detectable source-to-source and batch-to-batch variations in diastereomer ratios.
RESUMEN
The complex [Co(bdt)(2)](-) (where bdt = 1,2-benzenedithiolate) is an active catalyst for the visible light driven reduction of protons from water when employed with Ru(bpy)(3)(2+) as the photosensitizer and ascorbic acid as the sacrificial electron donor. At pH 4.0, the system exhibits very high activity, achieving >2700 turnovers with respect to catalyst and an initial turnover rate of 880 mol H(2)/mol catalyst/h. The same complex is also an active electrocatalyst for proton reduction in 1:1 CH(3)CN/H(2)O in the presence of weak acids, with the onset of a catalytic wave at the reversible redox couple of -1.01 V vs Fc(+)/Fc. The cobalt-dithiolene complex [Co(bdt)(2)](-) thus represents a highly active catalyst for both the electrocatalytic and photocatalytic reduction of protons in aqueous solutions.
