Robby Vroemans

Publication date: 15 November 2024

Source: European Polymer Journal, Volume 220

Author(s): Cong Shen, Ruiqi Shao, Wei Wang, Xianyan Wu, Baoming Zhou, Lihuan Zhao, Amna Siddique, Zhiwei Xu

This review summarizes the latest developments in using the versatile chemical properties of o-phthalaldehyde (OPA) in different fields, as shown in the left panel. It covers the discussion of the OPA-amines or OPA-amines-thiols reactions to produce chromophoric materials that have been used in the frontier research of chemical sciences, harnessing the unique chemical properties in organic synthesis, designing photosensitive polymers, and using them in the health sector.

Abstract

Ortho-Phthaldehyde (OPA) is one of the isomers of benzenedicarbaldehydes. It exhibits distinctive chemical properties stemming from the closely attached dicarbaldehyde groups. Since its development, it has been widely employed as a potent disinfectant, owing to its inherent antimicrobial properties. OPA has the ability to form a fluorescent product with primary amines, making it useful for detecting and estimating various biogenic amines, peptides, and proteins in bodily fluids. Moreover, the combination of thiol and amine with OPA produces a more sensitive fluorogenic compound, significantly enhancing the sensitivity and specificity of OPA-based analytical techniques. This review summarizes recent developments in biochemical analysis using OPA. It also discusses key achievements in the development of photoactive polymers. Additionally, it covers the use of OPA as a synthetic precursor to achieve small molecules with unique structures that have become increasingly important in various fields of scientific research from 2004.

Publication date: December 2024

Source: Molecular Catalysis, Volume 569

Author(s): Xiaohong Ren, Zeming Rong, Xiaoqiang Yu

This review discusses the design and synthesis of metal-organic cages (MOCs) through building blocks, metal sites, size and cavities, and postmodification synthesis. Research on MOCs in the field of photocatalysis is highlighted, which mainly includes photocatalytic hydrogen production, photocatalytic CO₂ reduction as well as photocatalytic organic transformation and photocatalytic H₂O₂ production.

Abstract

Metal-organic cages (MOCs) are a class of compounds formed through the coordination of metal ions with organic ligands to create well-defined and cage-like structure. These unique structures offer versatile environments for catalyzing a wide range of chemical reactions. The catalytic capabilities of MOCs are significantly influenced by the nature of the metal ions, functional ligands, and the cage structure. Notably, the confined spaces within MOCs can lead to enhanced reaction efficiencies, particularly in processes such as light-induced hydrogen generation and the photocatalytic reduction of CO₂. Furthermore, MOCs show great potential in photo-organic synthesis due to the cage structure, which provides a confined environment and allows for encapsulating organic molecules, making them useful for improving the selectivity and efficiency of catalytic process. This review reports the development of MOCs for photocatalysis, focusing on the structural design and regulation strategy to build functional MOCs for photocatalytic hydrogen production, CO₂ reduction, organic transformation. Insights into the photocatalysis are discussed including the challenges and further research direction in MOC-based photocatalysis.

Nature, Published online: 18 September 2024; doi:10.1038/d41586-024-02985-3

Industry research funding is vastly eclipsing academia’s spend, but healthy development demands broad input.

This review examines liquid organic hydrogen carriers (LOHCs) as a solution for global hydrogen logistics. The LOHC process involves hydrogenation for storage and dehydrogenation for reconversion. Various LOHC materials and catalytic hydrogenation processes are discussed, focusing on high-purity and low-purity hydrogen feedstocks. The economic viability is emphasized, particularly in relation to direct storage of minimally purified hydrogen from diverse sources.

Abstract

Liquid organic hydrogen carriers (LOHCs) are emerging as a promising solution for global hydrogen logistics. The LOHC process involves two primary chemical reactions: hydrogenation for hydrogen storage and dehydrogenation for hydrogen reconversion. In the exothermic hydrogenation reaction, hydrogen-lean compounds are converted to hydrogen-rich compounds, storing hydrogen from various sources such as water electrolysis, fossil fuel reforming, biomass processing, and industrial by-products. Conversely, hydrogen is extracted from hydrogen-rich compounds through an endothermic dehydrogenation reaction and supplied to several hydrogenation utilization offtakers. This review article discusses the development trends in catalytic hydrogenation processes for various LOHC materials, including benzene, toluene, naphthalene, biphenyl-diphenylmethane, benzyltoluene, dibenzyltoluene, and N-ethylcarbazole. It introduces references for catalytic hydrogenation processes utilizing both high-purity and low-purity (alternatively, mixed) hydrogen feedstocks, with particular emphasis on low-purity hydrogen applications. The direct storage of hydrogen with minimal purification, using by-product hydrogen and mixed hydrogen from hydrocarbon and biomass reforming, is crucial for the economic viability of this hydrogen carrier system.

Nature, Published online: 12 September 2024; doi:10.1038/d41586-024-02899-0

Jane Kilcoyne and colleagues took action after calculating that their biotoxin chemistry lab produced 4000 kilograms of waste per year, none of which was recyled.

The direct amidation of esters is converted from a ball-milled process into a continuous solvent-minimised reactive extrusion protocol capable of delivering 500 grams (1.3 mols) of amide product over a continuous operation for 7 hours. Key to this, was translation of heating profiles used for the ball-milling study directly to the extruder and consideration of the physical form of input substrates.

Abstract

Herein, we report on the translation of a small scale ball-milled amidation protocol into a large scale continuous reactive extrusion process. Critical components to the successful translation were: a) understanding how the different operating parameters of a twin-screw extruder should be harnessed to control prolonged continuous operation, and b) consideration of the physical form of the input materials. The amidation reaction is applied to 36 amides spanning a variety of physical form combinations (liquid-liquid, solid–liquid and solid-solid). Following this learning process, we have developed an understanding for the translation of each physical form combination and demonstrated a 7-hour reactive extrusion process for the synthesis of an amide on 500 gram scale (1.3 mols of product).

We developed an original method for thiocyanating C−H bonds in various phenols and their derivatives using readily available materials via electrogenerated (SCN)₂ and its Zn(II) complex. The process led to a diverse range of target products with yields of 36–97 % (include the drug riluzole and precursors for toltrazuril and ponazuril) under mild conditions.

Abstract

We developed an original method for thiocyanation of hydroxy- and alkoxy-substituted benzenes (including naturally occurring compounds) using electrogenerated thiocyanogen, (SCN)₂. The presence of zinc chloride as a Lewis acid significantly enhances reaction efficiency by activating thiocyanogen. Cyclic voltammetry of the reactants and their combinations was employed to optimize reaction conditions and investigate the proposed mechanisms. This method demonstrated broad synthetic utility, leading to mono- and bis-thiocyanated arenes and various heterocycles with yields 36–97 %. Notable products include the neuroprotective drug riluzole and precursors for the antiprotozoal drugs toltrazuril and ponazuril.

Nature Reviews Chemistry, Published online: 09 September 2024; doi:10.1038/s41570-024-00647-6

Chem Kids is a science camp where children ages 10 to 12 years old learn the notoriously difficult subject of organic chemistry.

Nature Catalysis, Published online: 09 September 2024; doi:10.1038/s41929-024-01213-5

Sulfilimines are a class of chiral molecules that bear S(IV) stereocentres, which are of high value in drug discovery but difficult to synthesize. Now the authors report a chemo- and enantioselective Chan–Lam S-arylation of sulfenamides with arylboronic acids that delivers diaryl and alkyl aryl sulfilimines.

Nature Communications, Published online: 30 August 2024; doi:10.1038/s41467-024-52006-0

Hydrogen sulfide is essential in many biological processes and a promising cancer imaging and signalling molecule and therapeutic agent, but the potential applications are hindered by its low endogenous levels. Here, the authors develop a nanoplatform based on H2S-responsive self-immolative poly(thiocarbamate) with localized H2S signal amplification capability and use the nanoplatform to encapsulate an H2S-responsive fluorescent probe or an anticancer prodrug.

It was early February 1965. The Woodward-Hoffmann collaboration had ended with the publication of their January 1965 JACS communication. Hoffmann was applying extended Hückel calculations to many topics in organic chemistry. But the moment he saw the molecular orbital energy level crossing, of MOs from bonding to antibonding MOs in the thermal [2+2] cycloaddition, a Eureka moment arrived. He knew this was the reason those reactions were thermally forbidden and photochemically allowed.

Abstract

On May 1, 1965, Roald Hoffmann and R. B. Woodward published their second joint communication, Selection Rules for Concerted Cycloaddition Reactions, in the Journal of the American Chemical Society. Herein is presented a historical analysis of Woodward and Hoffmann's determination of the mechanism of cycloadditions. This analysis is based on thorough analyses with Roald Hoffmann of his 1964 and 1965 laboratory notebooks and his archived documents and on numerous in-person, video, and email interviews. This historical research pinpoints several seminal moments in chemistry and in the professional career of Hoffmann. For example, now documented is the fact that Woodward and Hoffmann had no anticipation that their collaboration would continue after the publication of their first 1965 communication on electrocyclizations. Also pinpointed is the moment in Hoffmann's professional and intellectual trajectories that he became a full-fledged, equal collaborator with Woodward and Hoffmann's transition from a “calculator” to an “explainer.”

Nature, Published online: 27 August 2024; doi:10.1038/d41586-024-02667-0

An interspecies endurance test, and a defence of Darwin’s reticence on the origins of life, in this week’s snippets from Nature’s past.