Chiral Selective Chemistry Induced by Natural Selection of Spin‐Polarized Electrons

The search to understand the origin of homochirality in nature has been ongoing since the time of Pasteur. Previous work has shown that DNA can act as a spin filter for low‐energy electrons and that spin‐polarized secondary electrons produced by X‐ray irradiation of a magnetic substrate can induce chiral selective chemistry. In the present work it is demonstrated that secondary electrons from a substrate that are transmitted through a chiral overlayer cause enantiomeric selective chemistry in an adsorbed adlayer. We determine the quantum yields (QYs) for dissociation of (R)‐ or (S)‐epichlorohydrin adsorbed on a chiral self‐assembled layer of DNA on gold and on bare gold (for control). The results show that there is a significant difference in the QYs between the two enantiomers when adsorbed on DNA, but none when they are adsorbed on bare Au. We propose that the effect results from natural spin filtering effects cause by the chiral monolayer.     

Prometabolites of 5‐Diphospho‐myo‐inositol Pentakisphosphate

Diphospho‐myo‐inositol phosphates (PP‐InsP_y) are an important class of cellular messengers. Thus far, no method for the transport of PP‐InsP_y into living cells is available. Owing to their high negative charge density, PP‐InsP_y will not cross the cell membrane. A strategy to circumvent this issue involves the generation of precursors in which the negative charges are masked with biolabile groups. A PP‐InsP_y prometabolite would require twelve to thirteen biolabile groups, which need to be cleaved by cellular enzymes to release the parent molecules. Such densely modified prometabolites of phosphate esters and anhydrides have never been reported to date. This study discloses the synthesis of such agents and an analysis of their metabolism in tissue homogenates by gel electrophoresis. The acetoxybenzyl‐protected system is capable of releasing 5‐PP‐InsP₅ in mammalian cell/tissue homogenates within a few minutes and can be used to release 5‐PP‐InsP₅ inside cells. These molecules will serve as a platform for the development of fundamental tools required to study PP‐InsP_y physiology.     

Tris(4‐bromophenyl)aminium hexachloridoantimonate (`Magic Blue'): a strong oxidant with low inner‐sphere reorganization

Both the radical cation tris(4‐bromophenyl)aminium hexachloridoantimonate (`Magic Blue'), (C₁₈H₁₂Br₃N)[SbCl₆], (I), and neutral tris(4‐bromophenyl)amine, C₁₈H₁₂Br₃N, (II), show extremely similar three‐bladed propeller structures with planar N atoms. Key geometric features, such as the C—N bond distances and the angles between the planes of the aryl groups and the central NC₃ plane, are identical within experimental uncertainty in the two structures. This contrasts with the significant structural changes observed on oxidation of more electron‐rich triarylamines, where resonance contributes to the stabilization of the radical cation, and suggests that, in general, more strongly oxidizing triarylaminium cations will have lower inner‐sphere reorganization energies than their lower‐potential analogues.     

The Dihydropyrone Diels–Alder Reaction: Development and Application to the Synthesis of Highly Functionalized 1-Oxa-4-decalones

A facile method for the synthesis of highly functionalized 1-oxadecalone derivatives is described via the Diels–Alder reaction of 2,3-dihydro-4-pyrone dienophiles with electron rich dienes. By this process a variety of functional groups and substitution patterns can be incorporated into the oxadecalone framework.     

The Stability of the Oxidation State +4 in Group 14 Compounds from Carbon to Element 114

The stability of the oxidation state +4 decreases from silicon to element 114, as shown by relativistic and nonrelativistic calculations on the hydrides, fluorides, and chlorides of the Group 14 elements (the energies of the decomposition reaction (1) are given in the plot). Thus it is unlikely that superheavy element 114, which may have stable isotopes due to its magic numbers of protons and neutrons, can be studied by atom-at-a-time chemistry in the oxidation state +4.     

Pd-catalysed C–H functionalisation of free carboxylic acids

Pd-catalysed C–H functionalisation of free carboxylic acids has drawn significant attention over the last few years due to the predominance of carboxylic acid moieties in pharmaceuticals and agrochemicals. But their coordinating ability was overlooked and masked by exogenous directing groups for a long time. Even other crucial roles of carboxylic acids as additives and steric inducers that directly influence the mode of a reaction have been widely neglected. This review aims to embrace all of the diverse aspects of carboxylic acids except additive and steric effects by concisely and systematically describing their versatile role in Pd-catalysed proximal and distal C–H activation reactions that could be implemented in the pharmaceutical and agrochemical industries. In addition, the mechanistic perspectives along with several recent strategies developed in the last few years discussed here will serve as educational resources for future research.

Pd-catalysed C–H functionalisation of free carboxylic acids has drawn significant attention over the last few years due to the predominance of carboxylic acid moieties in pharmaceuticals and agrochemicals.     

Prototyping an ionization source for non-engineers

Novel mass spectrometry (MS) based analytical platforms have enabled scientists to detect and quantify molecules within biological and environmental samples more accurately. Novel MS instrumentation starts as a prototype and, after years of development, can become a commercial product to be used by the larger MS community. Without the initial prototype, many MS-based instruments today would not be produced. Additionally, biotechnology companies are the main drivers for research, development, and production of novel instruments, but the tools for prototyping instrumentation have never been more accessible. Here, we present a tutorial on prototyping instrumentation through the case study of developing the Next Generation IR-MALDESI source to show that an engineering degree is not required to design and construct a prototype instrument with modern hardware and software. We discuss the prototyping process, the necessary skills required for efficient prototyping, and information about common hardware and software used within initial prototypes.