Biolec

Unlocking a Cleaner Way to Do Chemistry

Daniel Morton — Tue, 30 Sep 2025 15:11:48 +0000

Unlocking a Cleaner Way to Do Chemistry Daniel Morton Tue, 09/30/2025 - 09:11

Daniel Morton

Taking the heat out of chemical manufacturing

For nearly two centuries chemists have relied on a simple principle when building molecules and materials: to make something new you have to apply energy, sometimes in the form of chemical energy, but most often in the form of heat.

From producing plastics to creating life-saving medicines, many of the chemical reactions that form the foundation of our modern world are driven by thermal energy, often generated by burning fossil fuels. This approach, while effective, is often incredibly energy-intensive and can lead to a host of other issues, from unwanted byproducts to a large carbon footprint. In essence it is like using a sledgehammer to build a delicate piece of furniture, while it might get the pieces together, it’s inefficient, causes unnecessary damage, and creates a lot of waste in the process.

But what if there was a better way? What if we could take the heat out of chemical manufacturing and use a more precise, sustainable energy source?

RASEI fellows are part of a growing wave of research that is doing just that by using light to drive chemical transformations. This isn’t about using light to just heat things up, it’s about harnessing the specific energy of photons to activate molecules in a targeted and efficient way. This approach, known as photocatalysis, is unlocking a cleaner, more controlled way to build the molecules we need. It is poised to transform everything from the creation of pharmaceuticals to the development of new and sustainable materials and plastics.

The shift to light-driven chemistry is not merely an academic exercise; it is a critical step toward a more sustainable and efficient industrial future. RASEI researchers, working across a range of national collaborations, have published more than 15 research papers in the past year, reflecting their commitment to innovation in this space. The research approaches the problem from a range of perspectives, exploring new chemical pathways and understanding the factors that control the efficiencies of these reacting.

The benefits of collaborative research the brings together a range of approaches to solve problems together is well illustrated in this roundup of recent research, including highlights from some large national collaborations, including contributions from U.S. Department of Energy funded Energy Frontier Research Centers (the Bio-inspired Light-Escalated Chemistry Center (BioLEC) and the Ensembles of Photosynthetic Nanoreactors (EPN)), and a National Science Foundation funded Center for Chemical Innovation (The Center for Sustainable Photoredox Catalysis (SuPRCat))

The summaries that follow provide a glimpse into this exciting work, detailing some of our latest discoveries and describing some of the tangible ways we are using light to create cleaner, more effective, and sustainable chemical processes.

Recent Research Highlights

Shining new light on an old problem: Breaking down ‘Forever Chemicals’ and building the next generation of materials

DOI: https://doi.org/10.1038/s41586-024-08327-7

Using a new catalyst and visible light, researchers have developed a chemical “scalpel” to degrade persistent pollutants and enable new, more precise chemical reactions.

The global challenge of “forever chemicals” has made the headlines for years. The carbon-fluorine (C–F) bond is one of the strongest in all of chemistry. For decades the sheer strength of the C–F bond has been a blessing and a curse. This incredible strength is what makes “forever chemicals”, like PFAS, so stable and useful in everything from non-stick pans to waterproof clothing but is also the reason that they are nearly impossible to break down. This has been a major contributor to the growing plastic waste crisis, and a key reasons for these compounds to be now known as one of the hardest pollutants to remove from the environment. A recent collaborative study, including RASEI Fellow Niels Damrauer, has a new solution for this problem. Development of a new catalyst that acts like a chemical scalpel, using blue light to precisely sever this famously inert bond. This approach not only offers a new way to degrade these persistent pollutants but also opens the door to using what were previously considered unreactive fluorinated molecules as building blocks for new chemical transformations and products.

This study is an illustrative example of a modern, collaborative approach to chemical innovation, as part of the NSF funded Center for Sustainable Photoredox Catalysis (SuPRCat). The research team came at the problem from two different angles: computational modeling and hands-on experimentation. The computational chemists first used powerful simulations to design and predict the behavior of a new organic catalyst. This helped them understand exactly how the catalyst could use low-energy, visible blue light to act as our "chemical scalpel," targeting and breaking the C–F bonds without the need for intense heat.

With this knowledge, the experimental chemists then created the catalyst in the lab. They showed that it could precisely snip the C-F bonds in a variety of molecules, demonstrating it was capable of both degrading persistent pollutants like PFAS and building new chemical structures that were previously difficult to construct.

The success of this research with a simple, abundant energy source like visible light shows that chemical reactions don’t have to be energy intensive. This research describes the power of precise, light-driven chemistry. By designing a catalyst that can target and activate some of the toughest bonds in chemistry, this team has not only revealed a potential path forward for degrading PFAS, but also demonstrated a new tool for chemists to build molecules in a cleaner and more energy efficient way.

A Chemical Blueprint for Turning Sunlight and Carbon Dioxide into Fuel

DOI: https://doi.org/10.1021/acsmaterialsau.5c00010

Combining computational design and experimental research, scientists have engineered a well-aligned connection between two materials, creating a more efficient pathway for clean energy.

The search to create carbon-neutral fuels from sunlight and carbon dioxide (CO₂) is one of the most exciting frontiers in sustainable energy. However, it is not enough to simply find a catalyst that can do the job, the real challenge lies in designing a system where all the components work in harmony. Imagine having two brilliant devices that are designed to work together, but they just can’t quite “talk” to each other. One is an incredible light sensitive material that captures sunlight, and the other is a special catalyst that can turn CO₂ into fuel. Previous research has found that when you bring these two components together their electronic energies were mismatched, causing poor ‘communication’ between the components, leading to the overall system being inefficient. Research led by RASEI Fellow Nate Neale uses a combination of advanced computational modeling and sophisticated experimentation to engineer an aligned electronic “bridge” to better connect the two materials, revealing a more efficient communication pathway, and hence a more effective overall system.

To solve the energy mismatch between the components the team adopted a feedback loop between computational modeling and experimentation. Powerful computational tools enabled the design of a range of potential linking molecules to explore how they would influence the electronic coupling between the silicon nanocrystal (the solar panel) and the catalyst. This approach acted as a “chemical blueprint”, allowing them to predict which design would create the most well-aligned connection. The team then took these findings to the lab and synthesized the most promising candidates and tested their real-world performance, comparing them to the properties predicted by the models. The results confirmed the predications and demonstrated that a specific, directly bonded molecular bridge was the most effective design.

This work describes a foundational step in the search for fuels synthesized by light. By developing an approach for the fundamental challenge of aligning a solar collector and a CO₂ catalyst, the team has provided a critical design guideline for building more efficient and powerful devices in the future.

Supercharging Chemistry: A jump forward in light-driven chemistry

DOI: https://doi.org/10.1126/science.adw1648

New collaborative research involving RASEI Fellow Niels Damrauer, addresses one of the ‘house of cards’ problems sometimes critical in photoredox catalysis.

Think about how you build a house of cards, every time you add a new card, there is a chance the whole thing will fall apart. This is a challenge often faced by chemists when they are trying to put together the components needed for a light-driven reaction. While this type of chemistry has huge potential in making the chemistry cleaner and more efficient, one of the features that can cause the whole thing to fall apart is a phenomenon called back electron transfer, where the desired chemical reaction is reversed, wasting energy and limiting the kinds of reaction that can be performed.

This collaborative team that includes RASEI Fellow Niels Damrauer from ��Ҵ�ý�ƽ�� and the groups of Garret Miyake and Robert Paton from Colorado State University in Fort Collins, has developed a new catalyst system that overcomes this fundamental obstacle. Published in a recent issue of Science, this work introduces a ‘super-reducing’ organic photoredox catalyst that, through preventing this backward reaction, opens the door to powerful new redox chemistries.

To better understand this discovery it is useful to think of the process like filling a bucket with water. In typical photoredox reactions, the bucket has a leak. As water is poured into the bucket (adding energy from light), some of it immediately drains out. This ‘leak’ is back electron transfer (BET), and it is especially problematic for complex and difficult reactions that require a lot of energy – it is like trying to fill a very leaky bucket with a very slow faucet.

The research collaboration, part of the National Science Foundation (NSF) funded Center for Chemical Innovation (CCI) Center for Sustainable Photoredox Catalysis (SuPRCat) took inspiration from nature to develop a solution for this problem. In photosynthesis plants use a process called proton-coupled electron transfer (PCET) to efficiently capture and store energy from sunlight, preventing energy loss. The team used a combination of sophisticated computational modeling and experimental investigation to design a catalyst that incorporates a similar mechanism. When the catalyst is energized by light it simultaneously transfers an electron to the target molecule and releases a proton (a hydrogen atom without its electron). This prevents the reaction from going backwards. This small change has a huge impact on how the reaction proceeds, it is essentially like patching the leak in the bucket as you pour the water in, ensuring that all the energy is used for the desired reaction.

As is often the case with research, the path to this discovery was not a straight line. The investigations initially focused on changing an existing catalyst framework. During these experiments they noticed that one of the new catalysts (PC40Me) was unexpectedly effective. The reduction of benzene is known to be a difficult transformation, but reactions catalyzed with PC40Me were possible. They found that under the reaction conditions PC40Me was transforming into a new chemical structure, and it was this new system that was efficient for the historically difficult reduction of benzene. Armed with this knowledge the team built new catalyst designs around the new structure, creating a more efficient catalyst (named PC8). PC8 is not only a ‘super reducer’ capable of reducing a broad range of aromatic compounds under mild conditions, it also proved to be extremely robust.

The key features of this work lies in its potential to be a new tool in how we design and build everything from pharmaceuticals to plastics. By providing a way to perform these difficult reduction reactions more efficiently and sustainably, this catalyst system has the potential to reduce waste and energy consumption. By opening the door to a transformation that has typically been thought of as difficult and un-efficient, it could act as an enabling technology in the synthesis of new classes of molecules that were previously out of reach.

This work highlights the power of collaboration. The combination of different tools and approaches that were required to complete this work would have been prohibitive for a single research group. By combining expertise the team were able to unravel this complex chemical puzzle, not only demonstrating a new transformation, but providing some design rules that can be used by future photocatalysis practitioners in reducing BET.

Finding the On switch for more efficient light-driven chemistry

DOI: https://doi.org/10.1038/s41467-025-60729-x

Collaboration led by RASEI members Obadiah Reid and Garry Rumbles solves a long-standing puzzle in important organic chemical transformation.

In the world of organic chemistry, making new molecules, the building blocks for everything from advanced electronic materials to pharmaceuticals, is a bit like being a chef. Chemists are always looking to improve the recipe, to make it faster, cheaper, more efficient, and produce less waste. In recent years one of the most exciting new ‘cooking techniques’ is nickel photocatalysis, which uses abundant, low-cost nickel and the power of light to enable chemists to build complex molecules under mild conditions.

This technique has emerged as something of a game-changer in building molecules, but it comes with a significant puzzle. The nickel catalyst, as it is normally added to a reaction, is in a dormant state (called a ‘pre-catalyst’). To get the reaction moving, the catalyst needs to be ‘woken up’. For years, scientists were not sure what the wake-up call was. The activation from pre-catalyst to the functioning catalyst was something of a black box, with numerous theories for what was happening. This led to the assumption that each reaction was unique, and each reaction required its own individual and complicated startup sequence. This has often required a lot of work to find the right ‘On switch’.

This collaborative study, led by RASEI researchers Obadiah Reid and Garry Rumbles at the National Renewable Energy Laboratory (NREL), brings together expertise from the SLAC National Accelerator Laboratory, Brookhaven National Laboratory, Argonne National Laboratory and Northeastern University. Together, the scientists have identified key features of the transformation from pre-catalyst to active catalyst. In the report, just published in Nature Communications, the team shows that there is a universal ‘On switch’ to start these powerful reactions, and the key to this transformation is light.

Imagine a high-tech machine delivered in a locked crate. You know that once you get it out and get it running, it can do amazing things, but you don’t have the key. For years, chemists were essentially trying to pick the lock in different ways every time they wanted to use it. This study describes a universal key for getting the crate open.

It was found that light, either directly, or transferred from another light-absorbing molecule, provide a jolt of energy that breaks a bond in the nickel pre-catalyst structure. This process, which is called photolysis, activates the nickel complex, getting it ready to do the chemistry. This initial step is something that has previously been proposed but never fully proven.

The team brought together a sophisticated array of tools to effectively investigate this mechanism, including incredibly fast laser systems that can watch chemical changes happen in fractions of a second. This allowed them to witness the ‘unlocking’ process in real-time and identify the exact sequence of events. They observed that after the initial light-induced bond breaking, the catalyst can then interact with molecules in the surrounding solvent, forming a temporary ‘reservoir’ that holds the catalyst in a state ready for the main reaction.

Building this body of evidence and developing these findings required a significant team effort, bringing together scientists from across the country, from multiple national labs and universities. RASEI Scientists at ��Ҵ�ý�ƽ�� and NREL used advanced spectroscopy to track the catalyst’s behavior, while researchers at SLAC used high-powered X-rays to confirm changes in the structure of the nickel complex. This combination of knowledge and experience with cutting-edge instrumentation was essential in providing a complete understanding of these reactions begin.

Development of unified explanation for how one of the most important tools in an organic chemist’s toolbox is activated has important implications. Understanding this fundamental activation step allows chemists to move from guessing to designing. Not only does this support improvement in the activation of existing reactions, it also provides opportunities to design new transformations, all of which will streamline the manufacture of chemical commodities, such as pharmaceuticals and materials.

Scientists move microscopic solar chemical factories out of water to unlock new transformations

DOI: https://doi.org/10.1039/D5SE00263J

Four RASEI Fellows work together to expand the potential applications of nanoparticle photocatalysts

We all understand the power of the sun. We feel it on a hot summer’s day, we see it harnessed in solar panels that power our homes and cities. Chemical photocatalysis develops approaches to shrink that ability to harness this energy down to a molecular scale, and uses this energy to power chemical reaction, to power the building of important organic molecules, the foundations of pharmaceuticals, materials, and clean fuels.

One of the technologies used to harness light on the molecular level are a class of particles called organic nanoparticles (oNPs). Think of them as tiny, solar-powered factories, expertly designed to capture light and use its energy to drive chemical reactions. The oNPs are made from readily available earth-abundant materials, offering a cheap, clean, and sustainable alternative to a range of more traditional chemical reactions, which can often rely on rare, expensive metals that are hard to get hold of and can produce significant waste.

However, the oNPs, for all their potential as chemical factories, do have one significant limitation, they can only be built and operated in water. This is a fundamental roadblock. While water is essential for life, it is often a very poor environment for performing chemical reactions and can be very detrimental for the complex and delicate sequence of chemical transformations required for producing valuable products. The full power of these nano-factories was, quite literally, stuck in the water.

To understand this challenge, imagine that you have designed the world’s most efficient and powerful engine. It is a true engineering breakthrough, but it comes with a major catch, it can only run while completely submerged in the ocean. This is fine if you want to get around in a submarine, or a boat, but you can’t put it into a car, or a plane, or a generator on land, where you need it most. The potential of this new innovation is trapped, unable to be used for countless valuable applications.

That is similar to the situation faced by the researchers, led by RASEI Fellows Stephen Barlow, Seth Marder, Obadiah Reid and Garry Rumbles. The oNPs were confined to water-based reaction media, in order to realize their full potential the team needed to find a way to move these delicate ‘nano-factories’ from water to the ‘dry-land’ of other chemical environments, known as non-aqueous solvents, without the oNPs collapsing or breaking down.

This study describes a solution that the team developed. They devised a multi-step process to gently coax the oNPs out of their native water environment and prepare them to operate in different chemical solvents.

The process they developed is analogous to making salad dressing in the kitchen. It begins by mixing the water containing the nanoparticles with an oily substance (in this study oleic acid) and shaking it. This creates an emulsion, where tiny droplets of water are suspended in the oil, much like a vinaigrette. During this process the oNPs leave the water and move into the oil, which wraps around them like a protective coating. Finally the water is gently remove, leaving the oNPs safely suspended in their new oily environment. The protective layer formed around them allows them to be seamlessly transferred to a range of new non-aqueous solvents, ready to get to work.

A key part of this study was demonstrating that the oNP ‘factories’ were still functional after their transfer to new solvent systems. Using a suite of tools the team were able to confirm that the transferred oNPs could still absorb light and perform the chemical reactions.

With these findings the potential of the oNPs can be explored and expanded. It reveals new opportunities, not only in putting together organic molecules, but also in the synthesis of clean fuels, such as hydrogen.

September 2025

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RASEI Secures Funding to Pursue Collaborative Team Science Programs to Address Climate Change Challenges

Anonymous — Sat, 27 Aug 2022 06:00:00 +0000

RASEI Secures Funding to Pursue Collaborative Team Science Programs to Address Climate Change Challenges Anonymous (not verified) Sat, 08/27/2022 - 00:00

Daniel Morton

Thirteen members of RASEI secured funding from the Department of Energy to participate in inter-disciplinary team science to address a range of challenges associated with combating climate change.

EFRC Funding Announcement

DOE EFRC Homepage

��Ҵ�ý�ƽ�� Announcement

In recent decades the scientific endeavor has expanded our knowledge and deepened our understanding of many of the imposing problems that face society. With this improved insight comes an appreciation that many of these issues are multi-faceted, far-reaching, and complex. The climate crisis is the toughest challenge for this generation and is an exceptionally intricate, systematic and multi-layered puzzle. In order to address this challenge in a holistic fashion we need teams of innovative scientists, from across a broad range of scientific and engineering fields, to work together in an inter-disciplinary fashion.

The Renewable and Sustainable Energy Institute (RASEI), a joint institute between ��Ҵ�ý�ƽ�� and the National Renewable Energy Laboratory (NREL), has prioritized becoming a hub for multi-disciplinary teams focused on climate solutions to work together. Development of this ecosystem anable teams to expand their collaboration across the entire RASEI community, extending to engagement with other academic, national labs and industrial partners along the Front Range. Through fostering a team environment, developing a culture of sharing and integration, RASEI aims to accelerate fundamental discoveries and their translation to applications and solutions that can be deployed to all communities in need.

In August of 2022 the Department of Energy (DOE) released $540 million of funding for research into clean energy technologies and low-carbon manufacturing, $400 million of which is to establish and continue multi-disciplinary team science at Energy Frontier Research Centers (EFRCs). Across the nation 43 EFRCs were funded, with 13 RASEI members involved in six of these Centers.

The EFRC program was established by the DOE Office of Basic Energy Sciences (BES) in 2009 to address the fact that global demand for energy is rapidly expanding, and the way in which energy is collected, stored and used needs to change. The goal of an EFRC is to bring together creative, multi-disciplinary scientific teams to tackle the toughest scientific challenges preventing advances in energy technologies. At the core of an EFRC's mission is to train the next generation of the scientific workforce, both in advanced technical techniques, and also in team science and developing the skills needed to work together to tackle large-scale problems. These Centers are initially funded for four years at about $4 million per year. If the Centers are successful, they can apply for renewed funding at the end of the first four years. Centers can only be renewed once.

For the 2022 funding announcement, two of the RASEI-infused EFRCs, one of which is based at NREL, were renewals of existing Centers, and the other four awards were to establish new research teams. You can find out more details about the different Centers in the summary boxes below.

The RASEI community is energized to be involved in these exciting collaborative opportunities, and the chance to work together across these teams as part of the RASEI community. Colorado’s U.S. Representative Ed Perlmutter captured this enthusiasm in his quote as part of the funding announcement:

“NREL and ��Ҵ�ý�ƽ��, among others, continue to lead our nation in their cutting-edge research and development of a variety of clean energy technologies and low-carbon manufacturing. Their work is essential in the fight to combat climate change and achieve important climate and clean energy goals in the future”

If you would like to keep up with the progress these teams make, check out the RASEI website or signup to our monthly newsletter.

Thirteen members of RASEI secured funding from the Department of Energy to participate in inter-disciplinary team science to address a range of challenges associated with combating climate change.

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A handle on charge reorganization

Anonymous — Fri, 01 Jul 2022 06:00:00 +0000

A handle on charge reorganization Anonymous (not verified) Fri, 07/01/2022 - 00:00

Nature Chemistry, 2022, 14, 720-722

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Resurrected microwave tool illuminates cutting-edge light-driven chemistry

Anonymous — Thu, 16 Jun 2022 06:00:00 +0000

Resurrected microwave tool illuminates cutting-edge light-driven chemistry Anonymous (not verified) Thu, 06/16/2022 - 00:00

Daniel Morton

Research Article

News and Views Highlight

Cell Chem Highlight

A century old technique has been revitalized to provide valuable insights for catalyzing chemical reactions.

Using advanced computer-aided design and coding tools, a long-overlooked microwave analysis technique uncovered new insights into cutting-edge, light-driven chemistry. The technique revealed that a component of the catalyst often considered inconsequential is actually responsible for a four-fold change in chemistry.

Organic chemistry underlies many of today’s manufacturing processes from pharmaceuticals to plastics, but these processes can often generate hazardous byproducts. Catalysts are a critical tool in for transitioning organic chemistry to a greener, more sustainable future. By accelerating the rate of a chemical reaction without itself being consumed, a catalyst molecule more efficiently uses raw materials, eliminates waste, and can avoid the use of toxic and hazardous substances. New research from a team of scientists at the Princeton University and the Renewable and Sustainable Energy Institute (RASEI; a joint institute between the National Renewable Energy Laboratory (NREL) and University of Colorado Boulder (��Ҵ�ý�ƽ��)) reveals key insights into how an important class of catalysts operate and offers a path to improving their performance.

Photoredox catalysts, that harness the energy from light (photo-) to transfer electrons to, or from, other molecules (what chemists refer to as reduction and oxidation respectively (hence ‘redox’)), takes the sustainability of catalysts to a higher level, by enabling reactions driven by light. Today, many researchers are seeking to understand how these photoredox catalysts systems work and to use this understanding to improve the efficiency of the redox reaction so it can be used at industrial scales. Many different variables can be modified to tune the reaction, such as the structure of the catalyst and the conditions of the reaction. A new discovery, published in Nature Chemistry in April 2022, revitalizes an long-overlooked analytical technique that has revealed the importance of a variable previously thought to be insignificant and uncover a new approach for improving these processes.

The breakthrough results from a collaboration between researchers from NREL and Princeton University. Light-driven catalysis has undergone a renaissance in recent years, and the Knowles group at Princeton have been one of the pioneers. Not only do these systems provide more sustainable alternatives to existing chemical transformations, but the gentler, more selective conditions under which they operate, (using light, instead of heat, or harsh chemicals), makes possible new and societally impactful chemistry.

However, to use these new reactions at manufacturing scale, a detailed understanding of how the reaction works is required. While organic chemists are fantastic at discovering and developing new reactions, they typically don’t have the tools to probe the details of a reaction. Enter the Rumbles-Reid group at RASEI—a team of physical inorganic chemists who specialize in investigating the “how” of reactions. By reviving an overlooked characterization technique, the RASEI team revealed unexpected details about how these catalysts work. This collaboration was made possible by an Energy Frontier Research Center (EFRC) funded by the U.S. Department of Energy, a collaborative project that brings together expertise from across a range of scientific disciplines. The Bioinspired Light-Escalated Chemistry (BioLEC) EFRC mission has a strong overlap with the RASEI sustainability goals. The team, led by Gary Rumbles and Obadiah Reid, used computational methods to modernize a technique that, despite being over 100 years old (it was first reported in 1915), has found little application in main-stream chemistry.

The photoredox catalyst exists as a pair of molecules, called an ionic pair, so named because each half carries an electronic charge. One half, that contains the metal iridium and is the molecule that interacts with light, is the cation (it has a positive (+) charge because it is ‘missing’ an electron), and the other half is called the anion (it has a negative (–) charge because it has an ‘extra’ electron). Consider the situation when you have two magnets, the opposite poles, or charges, attract, and in the solid form the anion (–) and cation (+) of the catalyst are tightly paired. When the ionic pair is placed in solution to perform the reaction it interacts with the molecules of the solvent, and the attraction between the pair is reduced. When you separate a pair of magnets there is still attraction, albeit weaker, and this is the same for the ionic pair. Common thinking is that during the reaction, while the iridium containing cation is being excited by the light energy, the anion is merely a bystander, close by, but insignificant. This investigation shows that is not the case.

In this approach, with the technical name of Flash-photolysis time-resolved dielectric-loss spectroscopy (fp-TRDL), the reaction sample is irradiated with microwave radiation and by measuring how the microwave changes over time as it passes through the solution the team can quantity how the electrons are shared across the ionic pair. Measurements are taken on the nanosecond scale; one nanosecond is one billionth of a second. Ionic pairs that are strongly bound in solution (two magnets stuck together), produce a strong signal, while an ionic pair that is only weakly bound (two magnets that are separated, but still have some attraction), produce a much weaker signal.

To modernize this technique the RASEI team addressed two critical components. Computer-aided design and simulations were used to fabricate a sample vessel capable of measuring these light-driven reactions, taking measurements in both the ground state (when no light is shining) and in the excited state (when light is being shone on the reaction). And computer code was written capable of analyzing and interpreting the ultra-fast readings taken. This was a great opportunity to showcase the value of this approach, says Garry Rumbles, RASEI Associate Director, and leader of a research thrust in BioLEC.

“Many previous studies with this technique were on fundamental systems, chosen to show how it worked, the chance to work on a catalyst of such current importance was really exciting”.

This revitalized approach provided unprecedented insights into how the catalyst ionic pair behaves in the reaction. Two catalyst systems were investigated, one where the ‘bystander’ anion was small, and the other where the anion was relatively large. When the anion is small, the ionic pair remains tightly bound in the reaction, but when the anion is large, the pair are separated in solution.

What does this mean for the reaction? When the reaction is exposed to light, two different things happen depending on the configuration of the catalyst pair:

Small anion: With a tightly bound ionic pair, the small anion is an active participant in the transformation. When the catalyst is excited by light the ionic pair reorganizes, stabilizing the excited state. This makes the catalyst effective at donating an electron to other chemicals in the reaction—a reduction transformation.
Large anion: With a weakly bound ionic pair, the large anion is not available to reorganize in concert with the excited state, so no stabilization is possible, and the catalyst now favors accepting an electron from other chemicals in the reaction—an oxidation transformation.

The measurements show that there is a four-fold difference in selectivity between these oxidation and reduction. Catalysts with a small anion proceed via a reduction pathway and those with a large anion through an oxidation pathway. Being able to control which path a reaction takes is important, not only to make the required products, but also to reduce impurities and waste.

This collaboration, operating at the intersection of cutting-edge light driven catalysis and reinvention of a century-old technique, reveals that molecules which were previously considered inconsequential bystanders can effectively switch the path of a reaction. Before this, organic chemists may have observed that the choice of anion made a difference to their reaction, but with no tools to better understand this, it remained an unexplored observation. This technique provides a valuable tool to investigate these kinds of reactions, and with better understanding comes improved results.

“This is already changing how we think about photoredox reactions in BioLEC” says Rumbles. “The vast promise of light-driven catalysis means that these kinds of detailed insights could pave the way to a greener and more sustainable way of building organic molecules.”

This collaborative report provides new insight into how reactive species interact.

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Ion-pair reorganization regulates reactivity in photoredox catalysts

Anonymous — Thu, 14 Apr 2022 06:00:00 +0000

Ion-pair reorganization regulates reactivity in photoredox catalysts Anonymous (not verified) Thu, 04/14/2022 - 00:00

Nature Chemistry, 2022, 14, 746-753

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