Comment in 2020

Molecular knots are evolving from academic curiosities to a practically useful class of mechanically interlocked molecules, capable of performing unique tasks at the nanoscale. In this comment, the author discusses the properties of molecular knots, and highlights future challenges for chemical topology.

The chemistry of carbon monoxide (CO) as a ligand has evolved significantly and transition-metal carbonyl complexes have been widely used as catalysts in many important catalytic processes. Here the authors comment on the recent progress of main-group element carbonyl complexes along with their future prospects.

Understanding the biogeochemistry of radionuclides in the environment is essential for effective isolation of nuclear waste in repositories, management of contaminated sites, ensuring long-term protection of our ecosystems, and limiting impacts on human health. Here the authors discuss the extreme complexity of this multidimensional chemistry problem, highlighting the outstanding open questions for the next generations of environmental radiochemists.

While sp²-hybridized carbon atoms in hydrocarbons typically contribute only one electron to their aromaticity, metals have more electrons from d or f orbitals available for participating in conjugation in organometallics, complicating the electron counting as well as analysis of their aromaticity. Here, the author comments on the challenges towards understanding aromaticity in organometallics and outlines several remaining questions that have yet to be answered.

The chemistry of stable low oxidation state group 2 metal compounds was initiated in 2007 and has since expanded rapidly, yielding many surprises. Here the author outlines advances in the field and discusses some of the open questions and challenges that remain to be answered in coming years.

Tight regulation of protein levels is so crucial for cellular function that mammalian cells have evolved two parallel degradation systems. This article discusses how these systems can be exploited to selectively target proteins of interest for therapeutic purposes.

Polymorphs, crystals with different structure and properties but the same molecular composition, arise from the subtle interplay between thermodynamics and kinetics during crystallisation. In this opinion piece, the authors review the latest developments in the field of polymorphism and discuss standing open questions.

The activation of very inert small molecules generally requires highly reactive activating species, but the high energy of these species makes their regeneration, and thus also catalytic turnover of the reaction, difficult to achieve. Here, the authors highlight the formidable challenge of overcoming the tradeoff between activating power and catalytic turnover in the context of main-group ambiphiles.

Chemical reaction networks (CRNs) are prototypical complex systems because reactions are nonlinear and connected in intricate ways, and they are also essential to understand living systems. Here, the author discusses how recent developments in nonequilibrium thermodynamics provide new insight on how CRNs process energy and perform sophisticated tasks, and describes open challenges in the field.

Over the past decade, momentous progress has been made in the characterization of late actinide compounds. Here the authors highlight how advances in spectroscopic and computational tools have developed our understanding of fundamental transplutonium bonding interactions, and discuss whether covalency and heterogeneity changes in 5f-orbital bonding could be harnessed in environmentally and industrially relevant systems.

Water can form a vast number of topological frameworks owing to its hydrogen-bonding ability, with 19 different forms of ice experimentally confirmed at present. Here, the authors comment on open questions and possible future discoveries, covering negative to ultrahigh pressures.

Glycans are ubiquitous in biology, but their complex structure and biosynthesis have challenged research of their wide-ranging roles. Here, the authors comment on current trends on the role of chemical methodologies in the field of glycobiology.

Airborne particles have significant impacts on health, visibility, and climate. Here, an overview of what is known about particle chemical composition is presented, along with open questions and challenges that are central to relating composition to life cycles and impacts.

Aerosols are highly dynamic, non-equilibrium systems exhibiting unique microphysical properties relative to bulk systems. Here the authors discuss the roles aerosols play in (bio)chemical transformations and identify open questions in aerosol-mediated reaction rate accelerations, aerosol optical properties, and microorganism survival.

Cloud droplets form in the atmosphere on aerosol particles, many of which result from nucleation of vapors. Here the authors comment on current knowledge and open questions regarding the condensational growth of nucleated particles to sizes where they influence cloud formation.

First-row transition metals play several roles in biological processes and in medicine, but can be toxic in high concentrations. Here the authors comment on the sensitive biochemistry and speciation chemistry of the first-row transition metals, and outline some of the remaining questions that have yet to be answered.

Isobe et al. recently introduced the phenine concept, whereby a 1,3,5-trisubstituted benzene system (a phenine unit) is used as a basic building block instead of an sp²-hybridized carbon atom. Now, they apply it in a concise synthesis of a nitrogen-doped phenine nanotube.

Science disengagement amongst school children remains a global challenge, leading to calls for more scientists to engage with the public. Here the authors discuss how a voluntary, flexible program can enhance graduate attributes in addition to addressing barriers to public engagement.

Organic polymers have demonstrated promise as photocatalysts, but their photocatalytic efficiencies remain relatively low. Now, borrowing principles from organic photovoltaics, heterojunctions of polymer photocatalysts and small molecule acceptors have been shown to have excellent solar hydrogen production efficiencies.

Organic 2D materials display valuable properties that are unique from their bulk counterparts, but creating covalent sheets with long-ranging order remains a formidable challenge. Now, reacting complementary monomers right below a surfactant monolayer on water proves to be a powerful method to create organic 2D materials with long-range order.