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Redox-active proanions of the type B12(OCH2Ar)12 [Ar = C6F5 (1), 4-CF3C6H4 (2), 3,5-(CF3)2C6H3 (3)] are introduced in the context of an experimental and computational study of the visible-light-initiated polymerization of a family of styrenes. Neutral, air-stable proanions 1-3 were found to initiate styrene polymerization through single-electron oxidation under blue-light irradiation, resulting in polymers with number-average molecular weights (Mn) ranging from ∼6 to 100 kDa. Shorter polymer products were observed in the majority of experiments, except in the case of monomers containing 4-X (X = F, Cl, Br) substituents on the styrene monomer when polymerized in the presence of 1 in CH2Cl2. Only under these specific conditions are longer polymers (>100 kDa) observed, strongly supporting the formulation that reaction conditions significantly modulate the degree of ion pairing between the dodecaborate anion and cationic chain end. This also suggests that 1-3 behave as weakly coordinating anions (WCA) upon one-electron reduction because no incorporation of the cluster-based photoinitiators is observed in the polymeric products analyzed. Overall, this work is a conceptual realization of a single reagent that can serve as a strong photooxidant, subsequently forming a WCA.

We report a discovery that perfunctionalized icosahedral dodecaborate clusters of the type B12(OCH2Ar)12 (Ar = Ph or C6F5) can undergo photo-excitation with visible light, leading to a new class of metal-free photooxidants. Excitation in these species occurs as a result of the charge transfer between low-lying orbitals located on the benzyl substituents and an unoccupied orbital delocalized throughout the boron cluster core. Here we show how these species, photo-excited with a benchtop blue LED source, can exhibit excited-state reduction potentials as high as 3 V and can participate in electron-transfer processes with a broad range of styrene monomers, initiating their polymerization. Initiation is observed in cases of both electron-rich and electron-deficient styrene monomers at cluster loadings as low as 0.005 mol%. Furthermore, photo-excitation of B12(OCH2C6F5)12 in the presence of a less activated olefin such as isobutylene results in the production of highly branched poly(isobutylene). This work introduces a new class of air-stable, metal-free photo-redox reagents capable of mediating chemical transformations.

In general, laboratory experiments focus on traditional chemical disciplines. While this approach allows students the ability to learn and explore fundamental concepts in a specific area, it does not always encourage students to explore interdisciplinary science. Often little transfer of knowledge from one area to another is observed, as students are given step-by-step instructions on how to complete their task with little involvement or problem solving. Herein, we provide an example of a real-time research laboratory experiment that is aimed at individual's exploration and development, with the scientific goal of discovering inexpensive, stable oxide semiconductors that can efficiently photoelectrolyze water to a useable fuel, hydrogen. Students create unique metal oxide semiconductors combinations, scan the samples for photoactivity using a purchased scan station, and report their findings to a collaborative database. A distinctive feature of the project is its ability to be implemented in a variety of educational levels with a breadth and depth of material covered accordingly. Currently, kits are being used in secondary education classrooms, at undergraduate institutions, or as outreach activities. The project provides students and scientists from different disciplines the opportunity to collaborate in research pertaining to clean energy and the global energy crisis.

Flavocytochrome P450 from Bacillus megaterium (P450BM3) is a natural fusion protein containing reductase and heme domains. In the presence of NADPH and dioxygen the enzyme catalyses the hydroxylation of long‐chain fatty acids. Analysis of the P450BM3 structure reveals chains of closely spaced tryptophan and tyrosine residues that might serve as pathways for high‐potential oxidizing equivalents to escape from the heme active site when substrate oxidation is not possible. Our investigations of the total number of enzyme turnovers before deactivation have revealed that replacement of selected tryptophan and tyrosine residues with redox inactive groups leads to a twofold reduction in enzyme survival time. Tryptophan‐96 is critical for prolonging enzyme activity, suggesting a key protective role for this residue. [ABSTRACT FROM AUTHOR]