Biofunctionalization of Polyoxometalates with DNA Primers,Their Use in the Polymerase Chain Reaction (PCR) and Electrochemical Detection of PCR Products

The bioconjugation of polyoxometalates (POMs), which are inorganic metal oxido clusters, to DNA strands to obtain functional labeled DNA primers and their potential use in electrochemical detection have been investigated. Activated monooxoacylated polyoxotungstates [SiW₁₁O₃₉{Sn(CH₂)₂CO}]^8? and [P₂W₁₇O₆₁{Sn(CH₂)₂CO}]^6? have been used to link to a 5′‐NH₂ terminated 21‐mer DNA forward primer through amide coupling. The functionalized primer was characterized by using a battery of techniques, including electrophoresis, mass spectrometry, as well as IR and Raman spectroscopy. The functionality of the POM‐labeled primers was demonstrated through hybridization with a surface‐immobilized probe. Finally, the labeled primers were successfully used in the polymerase chain reaction (PCR) and the PCR products were characterized by using electrophoresis.     

Rhodium‐Catalyzed Hydroformylation of 1,1‐Disubstituted Allenes Employing the Self‐Assembling 6‐DPPon System

A rhodium‐catalyzed hydroformylation of 1,1‐disubstituted allenes is reported. Using a Rh^I/6‐DPPon catalyst system, one can obtain β,γ‐unsaturated aldehydes in high regio‐ and chemoselectivity. The Z‐configured product is formed with up to >95 % selectivity when unsymmetrically 1,1‐disubstituted allenes are submitted to the reaction conditions. This is the first time that these interesting building blocks are accessible by hydroformylation of allenes. The utility of this methodology is demonstrated by further transformations of one of the obtained products.     

In Situ Generation of Difluoromethyl Diazomethane for [3+2] Cycloadditions with Alkynes

A novel approach to agrochemically important difluoromethyl‐substituted pyrazoles has been developed based on the elusive reagent CF₂HCHN₂, which was synthesized (generated in situ) for the first time and employed in [3+2] cycloaddition reactions with alkynes. The reaction is extremely practical as it is a one‐pot process, does not require a catalyst or the isolation of the potentially toxic and explosive gaseous intermediate, and proceeds in a common solvent, namely chloroform, in air. The reaction is also scalable and allows for the preparation of the target pyrazoles on gram scale.     

Reductive Catenation of Phosphine Antimony Complexes

Reactions of triarylphosphines with fluoroantimony(III) triflates give phosphine antimony(III) complexes, which undergo spontaneous reductive elimination of fluorophosphonium cations. The resulting phosphine antimony(I) complexes catenate to give the first examples of cationic antimony bicyclic compounds, [(R₃P)₄Sb₆]⁴⁺, featuring a bicyclo[3.1.0]hexastibine framework stabilized by four phosphine ligands. The unprecedented 14‐electron redox process illustrates the generality of the reductive catenation method.     

Whole‐Genome Sequencing of a Single Viral Species from a Highly Heterogeneous Sample

Metagenomic studies suggest that only a small fraction of the viruses that exist in nature have been identified and studied. Characterization of unknown viral genomes is hindered by the many genomes populating any virus sample. A new method is reported that integrates drop‐based microfluidics and computational analysis to enable the purification of any single viral species from a complex mixed virus sample and the retrieval of complete genome sequences. By using this platform, the genome sequence of a 5243 bp dsDNA virus that was spiked into wastewater was retrieved with greater than 96 % sequence coverage and more than 99.8 % sequence identity. This method holds great potential for virus discovery since it allows enrichment and sequencing of previously undescribed viruses as well as known viruses.     

The Unexpected Influence of Precursor Conversion Rate in the Synthesis of III–V Quantum Dots

Control of quantum dot (QD) precursor chemistry has been expected to help improve the size control and uniformity of III–V QDs such as indium phosphide and indium arsenide. Indeed, experimental results for other QD systems are consistent with the theoretical prediction that the rate of precursor conversion is an important factor controlling QD size and size distribution. We synthesized and characterized the reactivity of a variety of group‐V precursors in order to determine if precursor chemistry could be used to improve the quality of III–V QDs. Despite slowing down precursor conversion rate by multiple orders of magnitude, the less reactive precursors do not yield the expected increase in size and improvement in size distribution. This result disproves the widely accepted explanation for the shortcoming of current III–V QD syntheses and points to the need for a new generalizable theoretical picture for the mechanism of QD formation and growth.