Periodic Reporting for period 1 - PhotoFLPs (Design and Catalytic Applications of Photoactivated Frustrated Lewis Pairs)
Periodo di rendicontazione: 2023-10-01 al 2025-09-30
Chemical reactions make up the foundation of nearly every product we use in daily life — from medicines and plastics to fuels and fragrances. Yet many of these reactions still rely on rare metals, high energy consumption, and processes that generate waste. In a century increasingly defined by sustainability and the European Green Deal, chemistry faces an urgent need to reinvent itself. The PhotoFLPs project responds directly to this challenge by developing a new class of light-activated molecular systems capable of driving cleaner, smarter, and more efficient chemical transformations.
At the heart of PhotoFLPs are “Frustrated Lewis Pairs” (FLPs): combinations of molecules that would normally neutralize each other but are deliberately kept apart by their bulky shapes. This chemical “frustration” makes them highly reactive and able to activate strong chemical bonds — even without using metals. More recently, scientists have discovered that some of these pairs can exchange single electrons, forming so-called frustrated radical pairs (FRPs). These species open a completely new window for reactivity, allowing molecules to interact through radical, one-electron pathways that were once considered the exclusive domain of transition-metal catalysts. However, this behaviour has only been observed in a handful of examples, and the potential of these systems has remained largely unexplored.
The PhotoFLPs project, led by Dr Felix León at the Institute for Chemical Research (IIQ-CSIC/University of Seville) under the supervision of Dr Jesús Campos, aims to bring FLP chemistry into the light — literally. By using photons as a clean and renewable energy source, PhotoFLPs will design and study the first generation of photoactivated FLPs capable of switching their reactivity on and off through light. This concept merges two of the most dynamic frontiers in modern chemistry: light-driven catalysis and radical reactivity. It opens the door to performing demanding chemical reactions under mild conditions, without the need for expensive or toxic metal catalysts.
To achieve this, the project follows a progressive, three-stage approach.
Main-group photoactivation: The first phase explores purely main-group systems that can absorb light and form radical pairs. These will be tested in the activation of small, stable molecules such as hydrogen and carbon dioxide, providing fundamental insights into how light can control bond formation and cleavage.
Hybrid photo-systems: The second phase introduces combinations of main-group and first-row transition metals (such as iron, cobalt, or nickel) to merge the best of both worlds — the versatility of metals with the sustainability and tunability of FLPs.
Metal-only photo-radical pairs: Finally, the project aims to create transition-metal-only photoactivated FLPs, a completely new class of compounds that could perform unprecedented reactions, such as the transformation of ether and lignin waste materials into useful chemicals.
Beyond their scientific novelty, these discoveries could have far-reaching environmental and economic impacts. By finding new ways to convert low-value or waste feedstocks like carbon dioxide or lignin into valuable molecules, PhotoFLPs aligns closely with the UN Sustainable Development Goals (notably SDG 12, Responsible Consumption and Production) and the EU Green Deal’s push for climate-neutral chemistry. The project contributes to the long-term vision of building a circular chemical economy in which waste becomes a resource and sunlight replaces fossil energy as the driving force for synthesis.
The results of PhotoFLPs will be openly shared with the scientific community and the public. Publications will appear in leading open-access journals, and experimental data will be made available through European repositories following the FAIR principles. The project also places a strong emphasis on communication and outreach. Dr León will participate in major public events such as the European Researchers’ Night and the Seville Science Fair, as well as informal outreach activities (Pint of Science, Café con Ciencia). Through collaborations with the University of Seville’s communication office, the findings will be shared with local and national media, accompanied by clear explanations and engaging visuals. Educational visits to schools will help inspire future generations of scientists, while social-media campaigns using the hashtag #PhotoFLPs will reach a wider international audience.
Ultimately, PhotoFLPs aims to demonstrate that light-driven chemistry can do far more than illuminate our surroundings — it can illuminate new paths toward a sustainable and knowledge-based society. By blending fundamental research with environmental responsibility and public engagement, this Marie Skłodowska-Curie project exemplifies the transformative power of science in service of both innovation and the common good.
At the heart of PhotoFLPs are “Frustrated Lewis Pairs” (FLPs): combinations of molecules that would normally neutralize each other but are deliberately kept apart by their bulky shapes. This chemical “frustration” makes them highly reactive and able to activate strong chemical bonds — even without using metals. More recently, scientists have discovered that some of these pairs can exchange single electrons, forming so-called frustrated radical pairs (FRPs). These species open a completely new window for reactivity, allowing molecules to interact through radical, one-electron pathways that were once considered the exclusive domain of transition-metal catalysts. However, this behaviour has only been observed in a handful of examples, and the potential of these systems has remained largely unexplored.
The PhotoFLPs project, led by Dr Felix León at the Institute for Chemical Research (IIQ-CSIC/University of Seville) under the supervision of Dr Jesús Campos, aims to bring FLP chemistry into the light — literally. By using photons as a clean and renewable energy source, PhotoFLPs will design and study the first generation of photoactivated FLPs capable of switching their reactivity on and off through light. This concept merges two of the most dynamic frontiers in modern chemistry: light-driven catalysis and radical reactivity. It opens the door to performing demanding chemical reactions under mild conditions, without the need for expensive or toxic metal catalysts.
To achieve this, the project follows a progressive, three-stage approach.
Main-group photoactivation: The first phase explores purely main-group systems that can absorb light and form radical pairs. These will be tested in the activation of small, stable molecules such as hydrogen and carbon dioxide, providing fundamental insights into how light can control bond formation and cleavage.
Hybrid photo-systems: The second phase introduces combinations of main-group and first-row transition metals (such as iron, cobalt, or nickel) to merge the best of both worlds — the versatility of metals with the sustainability and tunability of FLPs.
Metal-only photo-radical pairs: Finally, the project aims to create transition-metal-only photoactivated FLPs, a completely new class of compounds that could perform unprecedented reactions, such as the transformation of ether and lignin waste materials into useful chemicals.
Beyond their scientific novelty, these discoveries could have far-reaching environmental and economic impacts. By finding new ways to convert low-value or waste feedstocks like carbon dioxide or lignin into valuable molecules, PhotoFLPs aligns closely with the UN Sustainable Development Goals (notably SDG 12, Responsible Consumption and Production) and the EU Green Deal’s push for climate-neutral chemistry. The project contributes to the long-term vision of building a circular chemical economy in which waste becomes a resource and sunlight replaces fossil energy as the driving force for synthesis.
The results of PhotoFLPs will be openly shared with the scientific community and the public. Publications will appear in leading open-access journals, and experimental data will be made available through European repositories following the FAIR principles. The project also places a strong emphasis on communication and outreach. Dr León will participate in major public events such as the European Researchers’ Night and the Seville Science Fair, as well as informal outreach activities (Pint of Science, Café con Ciencia). Through collaborations with the University of Seville’s communication office, the findings will be shared with local and national media, accompanied by clear explanations and engaging visuals. Educational visits to schools will help inspire future generations of scientists, while social-media campaigns using the hashtag #PhotoFLPs will reach a wider international audience.
Ultimately, PhotoFLPs aims to demonstrate that light-driven chemistry can do far more than illuminate our surroundings — it can illuminate new paths toward a sustainable and knowledge-based society. By blending fundamental research with environmental responsibility and public engagement, this Marie Skłodowska-Curie project exemplifies the transformative power of science in service of both innovation and the common good.
Description of the Activities Performed and Main Scientific Achievements
Throughout the duration of the PhotoFLPs project, extensive experimental and computational work was carried out to design, synthesise, and evaluate the reactivity of photoactivated Frustrated Lewis Pairs (FLPs). The research strategy followed the three main scientific objectives proposed in the work plan, progressively advancing from main-group systems to hybrid and fully metallic photoactive species.
In the first stage, a wide range of main-group FLP combinations was prepared and systematically studied under controlled photoactivation conditions. These included several phosphine–borane systems designed to exhibit low singlet–triplet energy gaps, as predicted by TD-DFT calculations. Upon irradiation, some of these pairs displayed evidence of single-electron transfer processes, consistent with the transient generation of frustrated radical pairs (FRPs). The experimental behaviour of these systems — confirmed by EPR and UV-Vis spectroscopy — represents one of the first direct demonstrations of light-induced radical generation within the FLP framework. The most promising systems are currently under further exploration to evaluate their potential in bond activation and catalytic transformations.
Building on this foundation, a second phase focused on hybrid main-group/transition-metal photoactivated systems. Several Fe(III), Co(III), and Ni(II) complexes were combined with tailored Lewis bases to create hybrid photo-FLPs capable of engaging in light-driven electron transfer. Preliminary photochemical screening has revealed encouraging reactivity patterns.
In parallel, exploratory work on transition-metal-only systems (TMOFLPs) was initiated, although in a very initial stage the first experiments are very encouraging to continue with this project.
During the course of these studies, an unexpected and highly significant discovery was made. The researcher identified an unusual photochemical behaviour in a heavy tetrylene (germylene) species, which exhibited an exotic excited-state dynamic relevant to the general understanding of photoactive main-group compounds. This finding, although outside the original scope of the project, is conceptually aligned with the PhotoFLPs objectives and highlights the breadth of knowledge generated through the fellowship. The work has been written up and deposited as a preprint in ChemRxiv, and it is currently under peer review in a leading high-impact chemistry journal.
The scientific outcomes of PhotoFLPs have been presented at several international conferences and symposia, where they have attracted considerable attention within the community of organometallic and photochemical researchers. These presentations have facilitated new collaborations and have contributed to establishing the project as a reference in the emerging field of photoactivated FLP and FRP chemistry.
In summary, the PhotoFLPs project has successfully demonstrated the feasibility of light-induced radical reactivity in main-group and hybrid FLPs, established a solid experimental platform for future catalytic development, and generated high-impact scientific results, including a publication currently under review. Together, these achievements represent a significant advance in the understanding of photochemical activation within cooperative molecular systems and pave the way toward sustainable, light-driven catalytic methodologies.
Throughout the duration of the PhotoFLPs project, extensive experimental and computational work was carried out to design, synthesise, and evaluate the reactivity of photoactivated Frustrated Lewis Pairs (FLPs). The research strategy followed the three main scientific objectives proposed in the work plan, progressively advancing from main-group systems to hybrid and fully metallic photoactive species.
In the first stage, a wide range of main-group FLP combinations was prepared and systematically studied under controlled photoactivation conditions. These included several phosphine–borane systems designed to exhibit low singlet–triplet energy gaps, as predicted by TD-DFT calculations. Upon irradiation, some of these pairs displayed evidence of single-electron transfer processes, consistent with the transient generation of frustrated radical pairs (FRPs). The experimental behaviour of these systems — confirmed by EPR and UV-Vis spectroscopy — represents one of the first direct demonstrations of light-induced radical generation within the FLP framework. The most promising systems are currently under further exploration to evaluate their potential in bond activation and catalytic transformations.
Building on this foundation, a second phase focused on hybrid main-group/transition-metal photoactivated systems. Several Fe(III), Co(III), and Ni(II) complexes were combined with tailored Lewis bases to create hybrid photo-FLPs capable of engaging in light-driven electron transfer. Preliminary photochemical screening has revealed encouraging reactivity patterns.
In parallel, exploratory work on transition-metal-only systems (TMOFLPs) was initiated, although in a very initial stage the first experiments are very encouraging to continue with this project.
During the course of these studies, an unexpected and highly significant discovery was made. The researcher identified an unusual photochemical behaviour in a heavy tetrylene (germylene) species, which exhibited an exotic excited-state dynamic relevant to the general understanding of photoactive main-group compounds. This finding, although outside the original scope of the project, is conceptually aligned with the PhotoFLPs objectives and highlights the breadth of knowledge generated through the fellowship. The work has been written up and deposited as a preprint in ChemRxiv, and it is currently under peer review in a leading high-impact chemistry journal.
The scientific outcomes of PhotoFLPs have been presented at several international conferences and symposia, where they have attracted considerable attention within the community of organometallic and photochemical researchers. These presentations have facilitated new collaborations and have contributed to establishing the project as a reference in the emerging field of photoactivated FLP and FRP chemistry.
In summary, the PhotoFLPs project has successfully demonstrated the feasibility of light-induced radical reactivity in main-group and hybrid FLPs, established a solid experimental platform for future catalytic development, and generated high-impact scientific results, including a publication currently under review. Together, these achievements represent a significant advance in the understanding of photochemical activation within cooperative molecular systems and pave the way toward sustainable, light-driven catalytic methodologies.
The PhotoFLPs project has significantly advanced the understanding of how light can be used to modulate molecular reactivity within the framework of Frustrated Lewis Pairs (FLPs) — a powerful concept in modern chemistry that enables bond activation without conventional transition-metal catalysts. Traditionally, FLPs rely on the static coexistence of electron donors and acceptors to activate small molecules through two-electron pathways. PhotoFLPs has gone beyond this established paradigm by exploring how light excitation can induce single-electron transfer events, opening a new frontier of photoactivated FLPs capable of performing radical-type chemistry in a controlled and sustainable way.
Scientific and Technological Advances
Photochemical activation of main-group FLPs:
The project has successfully designed and evaluated a variety of main-group Lewis acid/base combinations under irradiation. Some of these systems exhibited photochemical responses consistent with frustrated radical pair formation, as supported by spectroscopic and computational observations. These findings establish the conceptual feasibility of using light to trigger reactivity in FLPs, providing a foundation for future studies into photoinduced mechanisms of bond activation and catalytic turnover.
Exploratory studies on hybrid and transition-metal-only systems:
In line with the project objectives, initial synthetic and screening work was conducted to prepare and characterise hybrid and metal-only systems inspired by the FLP concept. Although these investigations remain at an early stage, the methodology and experimental framework developed within PhotoFLPs have paved the way for the systematic assessment of how metallic centres can participate in cooperative, light-driven reactivity. These studies constitute an important preparatory step for future research into more complex photoresponsive assemblies.
Discovery of an exotic photochemical behaviour in a germylene compound:
During the course of the investigations, an unexpected and scientifically significant observation was made: a heavy tetrylene (germylene) displayed an unusual photoresponse and excited-state behaviour distinct from typical main-group photochemistry. This serendipitous discovery, although not part of the initial objectives, directly complements the project’s goals by expanding knowledge on how main-group compounds can interact with light. The results of this study have already been disseminated through a ChemRxiv preprint and are currently under review in a high-impact international journal.
Potential Impacts and Future Perspectives
The PhotoFLPs project represents a conceptual leap in the field of molecular activation, demonstrating that photochemical energy can be harnessed to unlock new reaction pathways beyond classical two-electron chemistry. This paradigm offers the potential to reduce reliance on precious metals and energy-intensive processes, aligning closely with the objectives of the European Green Deal and the UN Sustainable Development Goals (notably SDG 12 and 13).
Looking ahead, several key needs and opportunities have been identified to ensure further progress and impact:
Further research and validation of light-induced mechanisms through ultrafast spectroscopy and detailed computational modelling.
Expansion of experimental scope to new families of FLPs and photoactive main-group compounds, aiming at catalytic C–O and C–H bond functionalisation.
Cross-sectoral collaboration with photochemical and materials-science partners to translate these concepts into practical photoactive materials and catalysts.
Support for intellectual-property evaluation and potential industrial transfer through the University of Seville’s Secretariat for Knowledge Transfer and Entrepreneurship (STCE) and the EU IPR Helpdesk.
Access to funding and infrastructure for demonstration-scale photochemical studies and for continued internationalisation through Horizon Europe and national initiatives.
Scientific and Technological Advances
Photochemical activation of main-group FLPs:
The project has successfully designed and evaluated a variety of main-group Lewis acid/base combinations under irradiation. Some of these systems exhibited photochemical responses consistent with frustrated radical pair formation, as supported by spectroscopic and computational observations. These findings establish the conceptual feasibility of using light to trigger reactivity in FLPs, providing a foundation for future studies into photoinduced mechanisms of bond activation and catalytic turnover.
Exploratory studies on hybrid and transition-metal-only systems:
In line with the project objectives, initial synthetic and screening work was conducted to prepare and characterise hybrid and metal-only systems inspired by the FLP concept. Although these investigations remain at an early stage, the methodology and experimental framework developed within PhotoFLPs have paved the way for the systematic assessment of how metallic centres can participate in cooperative, light-driven reactivity. These studies constitute an important preparatory step for future research into more complex photoresponsive assemblies.
Discovery of an exotic photochemical behaviour in a germylene compound:
During the course of the investigations, an unexpected and scientifically significant observation was made: a heavy tetrylene (germylene) displayed an unusual photoresponse and excited-state behaviour distinct from typical main-group photochemistry. This serendipitous discovery, although not part of the initial objectives, directly complements the project’s goals by expanding knowledge on how main-group compounds can interact with light. The results of this study have already been disseminated through a ChemRxiv preprint and are currently under review in a high-impact international journal.
Potential Impacts and Future Perspectives
The PhotoFLPs project represents a conceptual leap in the field of molecular activation, demonstrating that photochemical energy can be harnessed to unlock new reaction pathways beyond classical two-electron chemistry. This paradigm offers the potential to reduce reliance on precious metals and energy-intensive processes, aligning closely with the objectives of the European Green Deal and the UN Sustainable Development Goals (notably SDG 12 and 13).
Looking ahead, several key needs and opportunities have been identified to ensure further progress and impact:
Further research and validation of light-induced mechanisms through ultrafast spectroscopy and detailed computational modelling.
Expansion of experimental scope to new families of FLPs and photoactive main-group compounds, aiming at catalytic C–O and C–H bond functionalisation.
Cross-sectoral collaboration with photochemical and materials-science partners to translate these concepts into practical photoactive materials and catalysts.
Support for intellectual-property evaluation and potential industrial transfer through the University of Seville’s Secretariat for Knowledge Transfer and Entrepreneurship (STCE) and the EU IPR Helpdesk.
Access to funding and infrastructure for demonstration-scale photochemical studies and for continued internationalisation through Horizon Europe and national initiatives.