Andrew J. Bissette

Transmission of chirality through space and across length scales

Chirality is a fundamental property and vital to chemistry, biology, physics and materials science. The ability to use asymmetry to operate molecular-level machines or macroscopically functional devices, or to give novel properties to materials, may address key challenges at the heart of the physical sciences. However, how chirality at one length scale can be translated to asymmetry at a different scale is largely not well understood. In this Review, we discuss systems where chiral information is translated across length scales and through space. A variety of synthetic systems involve the transmission of chiral information between the molecular-, meso- and macroscales. We show how fundamental stereochemical principles may be used to design and understand nanoscale chiral phenomena and highlight important recent advances relevant to nanotechnology. The survey reveals that while the study of stereochemistry on the nanoscale is a rich and dynamic area, our understanding of how to control and harness it and dial-up specific properties is still in its infancy. The long-term goal of controlling nanoscale chirality promises to be an exciting journey, revealing insight into biological mechanisms and providing new technologies based on dynamic physical properties.

Asymmetric Conjugate Additions and Allylic Alkylations Using Nucleophiles Generated by Hydro‐ or Carbometallation

This Minireview discusses catalytic asymmetric conjugate addition and allylic alkylation reactions where the nucleophiles were generated in situ by hydrometallation or carbometallation. This exciting recent trend in asymmetric catalysis promises to expand the range of transformations available for the rapid and selective assembly of complex, functional molecules for both academic and industrial research. This Minireview aims to serve as a reference for studies reported to date and discusses the current state-of-the-art, scope and limitations of these processes.

Physical autocatalysis driven by a bond-forming thiol–ene reaction

Autocatalysis has been extensively studied because it is central to the propagation of living systems. Chemical systems which self-reproduce like living cells would offer insight into principles underlying biology and its emergence from inanimate matter. Protocellular models feature a surfactant boundary, providing compartmentalization in the form of a micelle or vesicle and any model of the emergence of cellular life must account for the appearance, and evolution of, such boundaries. Here, we describe an autocatalytic system where two relatively simple components combine to form a more complex product. The reaction products aggregate into micelles that catalyse molecular self-reproduction. Study of the reaction kinetics and aggregation behaviour suggests a mechanism involving micelle-mediated physical autocatalysis and led to the rational design of a second-generation system. These reactions are driven by irreversible bond formation and provide a working model for the autocatalytic formation of protocells from the coupling of two simple molecular components.

Visualization of the spontaneous emergence of a complex, dynamic, and autocatalytic system

Significance Chemical reproduction is central to biology, and understanding how chemical systems may give rise to complex systems that form self-reproducing cell-like structures is a leading goal for scientists. Here we use an ultrasensitive optical microscopy technique to directly monitor the formation and dynamics of self-replicating supramolecular structures at the single-particle level. As a result, we are able to quantify the kinetics of these systems and changes in nanoparticle distribution over time. Our ability to observe a variety of complex phenomena may contribute to understanding how cell-like systems can emerge from much simpler chemical components and provides a general route to studying assembly and disassembly on the nanoscale. Autocatalytic chemical reactions are widely studied as models of biological processes and to better understand the origins of life on Earth. Minimal self-reproducing amphiphiles have been developed in this context and as an approach to de novo “bottom–up” synthetic protocells. How chemicals come together to produce living systems, however, remains poorly understood, despite much experimentation and speculation. Here, we use ultrasensitive label-free optical microscopy to visualize the spontaneous emergence of an autocatalytic system from an aqueous mixture of two chemicals. Quantitative, in situ nanoscale imaging reveals heterogeneous self-reproducing aggregates and enables the real-time visualization of the synthesis of new aggregates at the reactive interface. The aggregates and reactivity patterns observed vary together with differences in the respective environment. This work demonstrates how imaging of chemistry at the nanoscale can provide direct insight into the dynamic evolution of nonequilibrium systems across molecular to microscopic length scales.

Systems chemistry: Selecting complex behaviour

Creating chemical systems that can model living systems is far from easy. However, the evolution of oil droplets in water through the application of artificial selective pressure to produce droplets with dramatically different — yet specific — behaviours, is an encouraging step in this direction.