The electrochemical reduction of CO2 to CO is a reaction of central importance for sustainable energy conversion and storage. Herein, structure-activity relationships of a series of imidazolium-based cocatalysts for this reaction are described, which demonstrate that the C4- and C5-protons on the imidazolium ring are vital for efficient catalysis. Further investigation of these findings led to the discovery of new imidazolium salts, which show superior activity as cocatalysts for the reaction, i.e., CO is selectively produced at significantly lower overpotentials with nearly quantitative faradaic yields for CO.

The cycloaddition of CO 2 into epoxides catalyzed by imidazolium and related salts continues to attract attention due to the industrial importance of the cyclic carbonate products. The mechanism of the imidazolium-catalyzed transformation has been proposed to require the participation of the acidic C2 proton. However, other simple salts without acidic protons, such as N,N,N,N-tetrabutylammonium chloride, are also efficient catalysts for the reaction. Hence, we decided to investigate the role of the ring protons of imidazolium salts in this reaction. To this end, we systematically studied the catalytic activity of a series of methylsubstituted imidazolium cations, in the presence of various halide anions, both by experiment and in silico. Our results demonstrate that, while stabilization of intermediates by C2, C4, or C5 protons in imidazolium salts takes place, it is the nucleophilicity of the anion that governs the overall activity, which is intimately related to the strength of the interactions between the cation and anion. Consequently, the reactivity of the halide anion strongly depends on the nature of the cation and cosolvents. This study completes the (known) mechanism and should facilitate the development of highly efficient catalysts.

The electrochemical reduction of carbon dioxide (CO 2 RR) currently attracts considerable attention as a way to make fuels and value-added products from CO 2 using renewable energy. Much effort has been devoted to developing efficient electrode materials for this reaction, while changing the composition of the electrolyte presents an alternative method to tune the properties of electrochemical systems. Additives of soluble organic promoters can act directly as catalysts, i.e. in combination with a noncatalytic electrode, or as cocatalysts to enhance the activity of the electrode. In this review we classify and describe the roles of various organic promoters, to reveal how they lower the onset potential and increase the current density of the CO 2 RR and also, in some cases, influence the selectivity of the reaction. In addition, we highlight the key considerations that are essential to prevent errors being made and are required to pave the way toward industrial implementation.

Exposure to biologically active substances such as therapeutic drugs or environmental toxicants can impact biological systems at various levels, affecting individual molecules, signaling pathways, and overall cellular processes. The ability to derive mechanistic insights from the resulting system responses requires the integration of experimental measures with a priori knowledge about the system and the interacting molecules therein. We developed a novel systems biology-based methodology that leverages mechanistic network models and transcriptomic data to quantitatively assess the biological impact of exposures to active substances. Hierarchically organized network models were first constructed to provide a coherent framework for investigating the impact of exposures at the molecular, pathway and process levels. We then validated our methodology using novel and previously published experiments. For both in vitro systems with simple exposure and in vivo systems with complex exposures, our methodology was able to recapitulate known biological responses matching expected or measured phenotypes. In addition, the quantitative results were in agreement with experimental endpoint data for many of the mechanistic effects that were assessed, providing further objective confirmation of the approach. We conclude that our methodology evaluates the biological impact of exposures in an objective, systematic, and quantifiable manner, enabling the computation of a systems-wide and pan-mechanistic biological impact measure for a given active substance or mixture. Our results suggest that various fields of human disease research, from drug development to consumer product testing and environmental impact analysis, could benefit from using this methodology.

Deep eutectic solvents (DESs) were applied to the electrochemical CO2 reduction reaction (CO2RR). Choline‐based DESs represent a non‐toxic and inexpensive alternative to room‐temperature ionic liquids (RTILs) as additives to the system or as electrolyte. Following the study on choline‐based DESs this approach was generalized and simple and organic‐soluble systems were devised based on the combination of organic chloride salts with ethylene glycol (EG), allowing the chlorides to be readily used as cocatalysts in the CO2RR. This approach negates the need for anion exchange and, because the chloride salt is usually the least expensive one, substantially reduces the cost of the electrolyte and opens the way for high‐throughput experimentation.