Publications

Rational design of photocatalysts for controlled polymerization: Effect of structures on photocatalytic activities

Over the past decade, the use of photocatalysts (PCs) in controlled polymerization has brought new opportunities in sophisticated macromolecular synthesis. However, the selection of PCs in these systems has been typically based on laborious trial-and-error strategies. To tackle this limitation, computer-guided rational design of PCs based on knowledge of structure-property-performance relationships has emerged. These rational…

Radical Addition to N,N-Diaryl Dihydrophenazine Photoredox Catalysts and Implications in Photoinduced Organocatalyzed Atom Transfer Radical Polymerization

Photoinduced organocatalyzed atom transfer radical polymerization (O-ATRP) is a controlled radical polymerization methodology catalyzed by organic photoredox catalysts (PCs). In an efficient O-ATRP system, good control over molecular weight with an initiator efficiency (I* = Mn,theo/Mn,exp × 100%) near unity is achieved, and the synthesized polymers possess a low dispersity (Đ). N,N-Diaryl dihydrophenazine catalysts typically produce polymers with…

A Rational Approach to Organo-Photocatalysis. Novel Designs and Structure-Property Relationships

Organic photocatalysts (PCs) are emerging as viable and more sustainable tools with respect to metal complexes. Recently, the field of organo-photocatalysis has experienced an explosion in terms of applications, redesign of well-established systems and identification of novel scaffolds. A rational approach to the structural modification of the different PCs is key to accessing unprecedented reactivity,…

Organocatalyzed Birch Reduction Driven by Visible Light

The Birch reduction is a powerful synthetic methodology that uses solvated electrons to convert inert arenes to 1,4-cyclohexadienes—valuable intermediates for building molecular complexity. Birch reductions traditionally employ alkali metals dissolved in ammonia to produce a solvated electrons for the reduction of unactivated arenes such as benzene (Ered < -3.42 V vs. SCE). Photoredox catalysts have…

Configuration mixing upon reorganization of dihedral angle induces rapid intersystem crossing…

A long excited state lifetime is a desirable quality of photocatalysts because it enables a higher probability of energy or electron transfer from the photocatalyst to a substrate. However, achieving a long lifetime in organic (metal-free) catalysts is challenged by competing rapid nonradiative relaxation from excited states and relatively slow intersystem crossing into long-lived states…

Organophotoredox Hydrodefluorination of Trifluoromethylarenes with Translational Applicability…

Abstract: Molecular editing such as insertion, deletion, and single atom exchange in highly functionalized compounds is an aspirational goal for all chemists. Here, we disclose a photoredox protocol for the replacement of a single fluorine atom with hydrogen in electron-deficient trifluoromethylarenes including complex drug molecules. A robustness screening experiment shows that this reductive defluorination tolerates…

A Unified and Practical Method for Carbon-Heteroatom CrossCoupling via Nickel/Photo Dual Catalysis

Abstract: While carbon-heteroatom cross coupling reactions have been extensively studied, many methods are specific and limited to a particular set of substrates or functional groups. Reported here is a general method that allows for C-O, C-N and C-S cross coupling reactions under one general set of conditions. We propose that an energy transfer pathway, in…

Organocatalytic C–H fluoroalkylation of commodity polymers

Abstract: Post-polymerization modification of commodity plastics diversifies their material properties and expands their potential applications. The thermal and chemical stability of polymers that contain aromatic rings, which represent a high-volume class of materials, makes it challenging to add functionality while retaining the molar mass (Mn) and molecular weight distribution (MWD) of the original polymer. Herein,…

Dimethyl‐dihydroacridines as Photocatalysts in the Organocatalyzed ATRP of Acrylate Monomers

Abstract: Development of photocatalysts (PCs) with diverse properties has been essential in advancement of organocatalyzed atom transfer radical polymerization (O‐ATRP). In this work, dimethyl‐dihydroacridines are presented as a new family of organic PCs, for the first time enabling controlled polymerization of challenging acrylate monomers via O‐ATRP. Structure‐property relationships for seven PCs are established, demonstrating tunable…

Energy Transfer to Ni-amine Complexes in Dual Catalytic, Light-driven C–N Cross-Coupling Reactions

Abstract: Dual catalytic light-driven cross coupling methodologies utilizing a Ni(II) salt with a photocatalyst (PC) have emerged as promising methodologies to forge aryl C–N bonds under mild conditions. The recent discovery that the PC can be omitted and the Ni(II) complex directly photoexcited suggests that the PC may perform energy transfer (EnT) to the Ni(II)…