Bioinspired Supercharging of Photoredox Catalysis for Applications in Energy and Chemical Manufacturing

Abstract

Metrics & MoreArticle Recommendations CONSPECTUS: For more than a decade, photoredox catalysis has been demonstrating that when photoactive catalysts are irradiated with visible light, reactions occur under milder, cheaper, and environmentally friendlier conditions. Furthermore, this methodology allows for the activation of abundant chemicals into valuable products through novel mechanisms that are otherwise inaccessible. The photoredox approach, however, has been primarily used for pharmaceutical applications, where its implementation has been highly effective, but typically with a more rudimentary understanding of the mechanisms involved in these transformations.From a global perspective, the manufacture of everyday chemicals by the chemical industry as a whole currently accounts for 10% of total global energy consumption and generates 7% of the world's greenhouse gases annually. In this context, the Bio-Inspired Light-Escalated Chemistry (BioLEC) Energy Frontier Research Center (EFRC) was founded to supercharge the photoredox approach for applications in chemical manufacturing aimed at reducing its energy consumption and emissions burden, by using bioinspired schemes to harvest multiple electrons to drive endothermically uphill chemical reactions. The Center comprises a diverse group of researchers with expertise that includes synthetic chemistry, biophysics, physical chemistry, and engineering. The team works together to gain a deeper understanding of the mechanistic details of photoredox reactions while amplifying the applications of these light-driven methodologies.In this Account, we review some of the major advances in understanding, approach, and applicability made possible by this collaborative Center. Combining sophisticated spectroscopic tools and photophysics tactics with enhanced photoredox reactions has led to the development of novel techniques and reactivities that greatly expand the field and its capabilities. The Account is intended to highlight how the interplay between disciplines can have a major impact and facilitate the advance of the field. For example, techniques such as time-resolved dielectric loss (TRDL) and pulse radiolysis are providing mechanistic insights not previously available. Hypothesis-driven photocatalyst design thus led to broadening of the scope of several existing transformations. Moreover, bioconjugation approaches and the implementation of triplet−triplet annihilation mechanisms created new avenues for the exploration of reactivities. Lastly, our multidisciplinary approach to tackling real-world problems has inspired the development of efficient methods for the depolymerization of lignin and artificial polymers.

Mechanistic Insights into the Charge Transfer Dynamics of Photocatalytic Water Oxidation at the Lipid Bilayer–Water Interface

“…16,20,29−31 Although such self-assembled systems have been utilized by several teams now, aiming essentially at maximizing product formation, little fundamental knowledge has been gathered on the effect of membrane-embedding on the rates of elementary electron transfer processes, where short-lived reactive intermediates are invoked. 32 In this work, time-resolved transient absorption spectroscopy and photoluminescence quenching experiments were performed on a photocatalytic water oxidation liposomes system, to unravel detailed photophysical and kinetic information on hole transfer process during photocatalysis. The molecules used for the liposomal self-assembly are shown in Scheme 1.…”

“…In such systems, the bulk solution, the interface, and the membrane core are characterized by distinct dielectric constants, which offers opportunities to prearrange redox-active sites and modify chemical reaction rates and mechanisms, compared to homogeneous conditions. ,− After pioneering but rare reports in the 1980s, several reports about photocatalytic water oxidation in liposomes have recently appeared. Typically, these photocatalytic systems consist of four components: the phospholipid that is the main component of the liposome membrane, an amphiphilic photosensitizer (PS), an amphiphilic catalyst, and a water-soluble sacrificial electron acceptor (SEA). ,,− Although such self-assembled systems have been utilized by several teams now, aiming essentially at maximizing product formation, little fundamental knowledge has been gathered on the effect of membrane-embedding on the rates of elementary electron transfer processes, where short-lived reactive intermediates are invoked …”

“… 16 , 20 , 29 − 31 Although such self-assembled systems have been utilized by several teams now, aiming essentially at maximizing product formation, little fundamental knowledge has been gathered on the effect of membrane-embedding on the rates of elementary electron transfer processes, where short-lived reactive intermediates are invoked. 32 …”

Development of a General Procedure To Access Recoverable Solid-Supported Photocatalysts for Use in Organic Synthesis

“…However, as the field of photoredox catalysis expands and finds increasing application in the pharmaceutical industry, the practicality and greenness of employing these bespoke photocatalysts require further optimization. 10 Transitionmetal-containing photocatalysts, typically derived from iridium or ruthenium, suffer from the high cost of non-renewable starting materials as well as laborious syntheses to access the requisite decorated ligands. 11 While organic photocatalysts have been explored as greener alternatives compared to inorganic photocatalysts, lengthy syntheses are often required.…”

Direct α-C–H Alkylation of Structurally Diverse Alcohols via Combined Tavaborole and Photoredox Catalysis

“…Biological systems provide attractive reactivity blueprints that can inspire chemists to improve the efficiency and selectivity of organic synthesis . Tavaborole, as a boron-containing compound, has been shown to possess excellent antimicrobial activities and approved in 2014 as an antifungal drug .…”