Volume 92, Issue 12

Host–guest interactions mediate many chemical and biochemical transformations and are extensively exploited in a number of industrially-relevant chemical processes. Many porous inorganic (e.g., zeolite) and molecular (e.g., metal-organic framework) hosts engage reagents in their environment through selective host–guest interactions. While researchers frequently capitalize on host–guest interactions to sequester chemical species or to catalyze reactions, these interactions can also be used to direct nanomaterial synthesis. In this Perspective we highlight the promise and opportunities for harnessing host–guest interactions to control the structure and dimensionality of materials. We focus our discussion on emerging strategies in soft chemistry and promising new directions which use porous ionic solids to direct the growth of complex nanoscale dimers and Janus nanoparticles.

The rapid expansion of photoredox catalysis and artificial photosynthesis has garnered renewed interest in the field of photochemistry. While porphyrins have been widely utilized for a variety of photochemical applications, corrole photochemistry remains underexplored, despite an exponential growth in corrole chemistry. Indeed, less than 4% of all corrole-related publications have studied the photochemistry of these molecules. Since corroles exhibit chemical properties that are distinct from porphyrins and related macrocycles, it is likely that this divergence would also be observed in their photochemical properties. This review provides a comprehensive summary of the extant corrole photochemistry literature. Corroles primarily serve as photosensitizers that transfer energy or an electron to molecular oxygen to form singlet oxygen or superoxide, respectively. While both of these reactive oxygen species can be used to drive chemical reactions, they can also be exploited for photodynamic therapy to treat cancer and other diseases. Although direct photochemical activation of metal–ligand bonds has been less explored, corroles mediate a variety of transformations, particularly oxygen atom transfer reactions. Together, these examples illustrate the diversity of corrole photochemistry and suggest that there are many additional applications yet to be discovered.

The synthetic tunability of semiconductor nanowires has enabled researchers to apply these materials in a variety of applications from energy harvesting to biological stimulation. One of the most intensely researched areas is the synthesis of branched nanowires, or nano-tree structures, owing to their high surface area. In this paper, we present a synthetic protocol that enables the growth of ultra-thin nanowire branches on a primary nanowire. Specifically, the method yields tightly distributed branches, whose locality is unique to our method. We furthermore induce the transformation of these branches into spheroidal superstructures. We explain how an Ostwald ripening-like mechanism can account for such a transformation. We suggest how our method can expand the synthetic toolset of branched nanowires, thus enabling the development of applications.

Conventional graphene electronics fail to leverage the exceptional surface-area-to-volume ratio of graphene due to the challenges imposed by arranging two-dimensional (2D) nanomaterials in three-dimensional (3D) spaces. Recently, a new topology of graphene, nanowire template 3D fuzzy graphene (NT-3DFG), has been developed to overcome this limitation. We provide an overview of the unique physical and chemical properties of NT-3DFG that are a direct consequence of the material structure and describe NT-3DFG’s promising applications in bioelectronics and energy-related research.

The development of a comprehensive renewable energy industrial chain becomes urgent since renewable energy will soon dominate the power generation. Among the industries, carbon dioxide reduction reaction (CO 2 RR), which uses energy to convert carbon dioxide into high-value products and reduce CO 2 in the atmosphere, is regarded as a promising and potential industrial application. The conventional H-type reactor shows limited catalytic activity toward CO 2 RR, leading to the incompatible combination with the massive renewable energy. The flow systems – flow-cell reactor and the membrane electrode assemblies – show the promising selectivity and activities of CO 2 RR products, meeting the criteria for industrial mass production. In this Perspective, I start by comparing the market price and annual global production of major CO 2 RR products with the necessary costs using technoeconomic analysis for industrial utilization. Subsequently, I systematically summarize the catalytic performances of the same copper catalyst in these reactors for CO 2 RR and discuss the possibility of industrialization. Owing to the distinctive catalytic behaviors in flow systems, I finally present prospects to investigate the catalytic mechanisms by developing various in-situ techniques in these flow systems to speed up the renewable energy industry.

MXene with two-dimensional layered structure and desirable electronic properties has emerged as a promising candidate to construct MXene-based composites towards various photocatalytic applications. As compared to the downhill-type photodegradation reactions, artificial photosynthesis often involves thermodynamic uphill reactions with a large positive change in Gibbs free energy. Recent years have witnessed the effectiveness of MXene in enhancing the photoactivity of MXene-based composites for solar fuel synthesis. In this review, we mainly focus on the applications of MXene-based composites for photocatalytic solar fuel production. We will start from summarizing the general synthesis of MXene-based composite photocatalysts. Then the recent progress on MXene-based composite photocatalysts for solar fuel synthesis, including water splitting for H 2 production, CO 2 reduction to solar fuels, and N 2 fixation for NH 3 synthesis is elucidated. The roles of MXene playing in improving the photoactivity of MXene-based composites in these applications have also been discussed. In the last section, perspectives on the future research directions of MXene-based composites towards the applications of artificial photosynthesis are presented.

Radical chemistry is tightly interwoven in proposed prebiotic synthetic pathways, reaction networks and geochemical scenarios that have helped shape our understanding of how life could have originated. Gas-phase prebiotic reactions involving electric discharge, vapour ablation by asteroidal and cometary impacts as well as ionising radiation all produce radicals that facilitate complex molecular synthesis. Reactions in the solid phase which are responsible for astrochemical syntheses can also take place through radicals produced via irradiation of protoplanetary/interstellar ice grains and dust particles. Aqueous-phase radical chemistry affords further molecular complexity promoting the production of precursors for the synthesis of biopolymers thought important for the emergence of life. Radical chemistry appears to be a common thread amongst all kinds of prebiotic investigations, and this Review aims to bring attention to a few selected examples. Some important historical studies and modern developments with respect to prebiotic chemistry are summarised through the lens of radical chemistry.

Intermolecular C( sp 3 )–H bond functionalization reactions promise to revolutionize how we synthesize organic molecules by enabling the introduction of functionality at previously inert sites. However, one of the greatest challenges in this research field is site-selectivity, wherein chosen C( sp 3 )–H bonds must be selectively functionalized and other C( sp 3 )–H bonds with similar stereoelectronic properties must remain intact. To address this problem, chemists have developed methods that rely on targeting innately more reactive C( sp 3 )–H bonds or on using pre-installed functional groups to direct a catalyst or reagent to a particular C( sp 3 )–H bond. However, such approaches invariably have limited applicability because only a handful of innately reactive C( sp 3 )–H bonds or those nearby certain functional groups can be functionalized with good site-selectivity. To overcome these limitations, chemists also have developed catalysts and reagents that control the site of C( sp 3 )–H bond functionalization and have begun to unlock the potential of these reactions to achieve the site-divergent functionalization of C( sp 3 )–H bonds, wherein the site of functionalization is changed by modulating the stereoelectronic properties of the catalyst or reagent. This short review will provide a summary of selected examples of catalyst- and reagent-controlled site-divergent intermolecular functionalization of C( sp 3 )–H bonds, the factors responsible for modulating the site selectivity of these reactions, and will identify potential areas worthy of future research in this field.

The novelty of this work lies in the experimental confirmation that alkylamines react with Nitric oxide (NO) in aqueous solution at room temperature and atmospheric pressure conditions releasing HNO. We combined spectroscopic, electrochemical, and kinetic techniques to describe the reactions intermediates and characterized end products determined by UV–vis, NMR, and GC-MS. Nitrosamine and propene were detected for the reactions of diethylamine and isopropylamine, showing differential mechanisms between primary and secondary alkylamines. Finally, mechanistic analysis using ab-initio methods was performed and compared with the molecular mechanism proposed for the decomposition of NONOates. The results are discussed in the context of the growing interest in the NO/HNO interconversion reactions, required to understand their overlapping and different reactivity.

It is always a great honor to be able to celebrate with colleagues the anniversary of a prestigious magazine. As I write this invited article for the celebration of the 60th Anniversary of publication of the IUPAC Journal, Pure and Applied Chemistry, I ponder upon my upbringing as a Puerto Rican academic, scientist, and chemist. The roads through school, academia, and life are often turbulent and not straightforward. Herein, I share a short recollection of my story as a young chemist and the aspirations I look forward to.