Photocatalysis and Light-Driven Chemistry

Light is one of the cleanest and most precise tools available to chemistry. It can activate molecules under mild conditions, initiate radical transformations, switch catalytic states, generate photoresponsive materials, and reveal intermediates that are difficult to observe by conventional methods.

The Ananikov Lab develops photocatalysis and light-driven chemistry as a broad scientific platform. The project connects organic synthesis, radical reaction mechanisms, catalyst dynamics, mass spectrometric monitoring, molecular photophysics, and photoresponsive materials. The goal is not only to use light for making molecules, but also to understand how catalytic systems evolve under irradiation.

This direction expands classical photocatalysis into a wider area of light-driven chemistry, where photons serve as reagent, trigger, switch, and analytical handle.

Project objectives

• Develop light-driven synthetic methods for atom-economical C–S and C–C bond formation.
• Control complex radical reaction networks in thiol–yne, thiol–yne–ene and related multicomponent transformations.
• Use visible light to access molecular complexity under mild and selective conditions.
• Reveal the real active species in photocatalytic systems by direct mechanistic monitoring.
• Develop Photo-Chem-ESI-MS and related approaches for observing photochemical reactions in real time.
• Investigate dynamic photocatalysis, including light-induced catalyst reconfiguration and preactivation.
• Explore light-responsive catalysts, luminescent molecules, and photoinduced materials formation.

Light-driven synthesis and radical selectivity

A major part of the project is devoted to radical reactions of alkynes, alkenes and sulfur-containing compounds. These reactions are attractive because they can form valuable C–S and C–C bonds with high atom economy. At the same time, they are mechanistically challenging: several radical pathways may compete, and selectivity must be controlled at every stage of the cascade.

The early development of a visible-light-mediated, metal-free thiol–yne click reaction demonstrated that inexpensive organic photocatalysts can replace metal-based systems and provide selective access to sulfur-functionalized alkenes. This approach is important for applications where metal contamination must be avoided, including materials and biologically relevant compounds.

The methodology was expanded to photocatalytic thiol–yne–ene coupling, where one-pot formation of C–S and C–C bonds gives densely functionalized products. The key challenge is to guide the radical sequence so that the desired intermolecular cascade dominates over side reactions. Reversible radical addition became an important mechanistic principle for understanding and controlling this selectivity.

Seeing photochemistry while it happens

Mechanistic observation is central to this research direction. Photochemical reactions often involve short-lived excited states, radicals, ions, catalyst-derived species and side products that appear only under irradiation. For this reason, the project develops and applies methods that allow direct observation of reaction mixtures while light is on.

Photo-Chem-ESI-MS combines photochemical activation with electrospray ionization mass spectrometry. This approach makes it possible to perform light-on/light-off experiments, detect intermediates, compare competing pathways and connect observed species with reaction outcome. The methodology is especially valuable for complex catalytic systems where the initially added catalyst is not necessarily the only active form.

The project also develops specialized detection strategies for neutral organic photocatalysts. For example, anion-enhanced ESI-MS using bromide interactions provides a way to visualize cyanoarene photocatalysts and their transformation products with improved sensitivity.

Dynamic photocatalysis and the ReAct-Light concept

A key conceptual development of this project is the transition from a static view of photocatalysis to a dynamic one. Classical schemes often show a photocatalyst as a single molecular structure that absorbs light, transfers an electron or energy, and returns unchanged to the initial state. In real systems, however, light may transform the catalyst into a family of new species.

The ReAct-Light concept describes reconfigurable active species under light. In this view, irradiation can generate active catalyst forms that differ from the starting photocatalyst. These species may have different absorption properties, redox behavior, stability and catalytic performance. Instead of treating every structural change as degradation, the project asks whether light-induced reconfiguration can be used as a productive design principle.

This idea has been demonstrated for phenothiazine-derived systems and further extended to cyanoarene photocatalysts. In the latter case, light-driven preactivation of 3DPAFIPN generates cyclized catalytic species with improved performance in thiol–yne–ene coupling. Thus, photocatalyst evolution becomes part of catalyst design.

Light-responsive catalysts, molecules and materials

The broader title “Photocatalysis and Light-Driven Chemistry" reflects the diversity of present and future projects. The field is not limited to photoredox organic synthesis. Light can also control organometallic geometry, switch catalytic performance, tune luminescent molecular systems and induce materials formation.

Photoresponsive bis-NHC-diarylethene palladium complexes illustrate how light can control organometallic structure and catalytic behavior. Photochemically generated iron ions can trigger hydrogel formation from sodium alginate and acrylamide. Phosphole derivatives demonstrate how molecular structure and conjugation tune fluorescence. Together, these studies show that light-driven chemistry provides a common language for synthesis, catalysis, analysis and materials science.

Research methods

The project integrates synthetic chemistry with detailed mechanistic analysis. Typical methods include photoreactor design, controlled irradiation experiments, online and offline ESI-HRMS, Photo-Chem-ESI-MS, EPR spectroscopy, UV–vis spectroscopy, fluorescence studies, cyclic voltammetry, NMR spectroscopy, isotope labeling, quantum-yield measurements, X-ray diffraction, kinetic analysis and DFT calculations.

The combination of these methods allows the laboratory to connect molecular structure, light absorption, catalyst evolution, radical pathways and synthetic outcome.

Publications

2026

Bis-NHC-Diarylethene Palladium Complexes: Dynamic Behavior and Self-Tuning Photoswitching
Angew. Chem. Int. Ed. 2026, e202522849. DOI: 10.1002/anie.202522849

Light-Driven Preactivation of 3DPAFIPN into Highly Active Photocatalytic Species
Chemistry – A European Journal 2026, 32, e202503363. DOI: 10.1002/chem.202503363

Dearomative Vinylation of Indoles via Multicomponent Photoredox Thiol-Yne-Heteroarene Coupling Reaction
Chemistry – A European Journal 2026, 32, e202503346. DOI: 10.1002/chem.202503346

2025

Enantioselective Synthesis of Cyclobutane-fused Heterocycles via Lewis Acid-Catalyzed Dearomative [2+2] Photocycloaddition of Indoles, Benzofurans, and Benzothiophenes with Alkenes
Angew. Chem. Int. Ed. 2025, e202513342. DOI: 10.1002/anie.202513342

Reconfiguration of Active Species under Light for Enhanced Photocatalysis
J. Am. Chem. Soc. 2025, 147, 22796–22805. DOI: 10.1021/jacs.5c05052

ESI-MS-Visualization of Cyanoarene Photocatalysts by Specific Supramolecular Interaction with Br-Anion
Chemistry—Methods 2025, e202400087. DOI: 10.1002/cmtd.202400087

2024

Sulfur in Waste-Free Sustainable Synthesis: Advancing Carbon–Carbon Coupling Techniques
Angew. Chem. Int. Ed. 2024, e202402109. DOI: 10.1002/anie.202402109

Reversible Radical Addition Guides Selective Photocatalytic Intermolecular Thiol-Yne-Ene Molecular Assembly
Angew. Chem. Int. Ed. 2024, e202314208. DOI: 10.1002/anie.202314208

2023

General Cross-Coupling Reactions with Adaptive Dynamic Homogeneous Catalysis
Nature 2023, 619, 87–93. DOI: 10.1038/s41586-023-06087-4

Photochemically Induced Formation of Adhesive Hydrogels from Sodium Alginate, Acrylamide, and Iron Sandwich Complexes
Chem. Commun. 2023, 59, 10532–10535. DOI: 10.1039/D3CC03129B

Studying Photochemical Transformations using Electrospray Ionization Mass Spectrometry (ESI-MS)
ChemPhotoChem 2023, e202200175. DOI: 10.1002/cptc.202200175

2022

Intermolecular Photocatalytic Chemo-, Stereo- and Regioselective Thiol–Yne–Ene Coupling Reaction
Angew. Chem. Int. Ed. 2022, 61, e202116888. DOI: 10.1002/anie.202116888

Yellow to Blue Switching of Fluorescence by the Tuning of the Pentaphenylphosphole Structure: Phosphorus Electronic State vs. Ring Conjugation
Phys. Chem. Chem. Phys. 2022, 24, 25307–25315. DOI: 10.1039/D2CP03723H

2020

Selectivity Control in Thiol–Yne Click Reactions via Visible Light Induced Associative Electron Upconversion
Chemical Science 2020, 11, 10061–10070. DOI: 10.1039/D0SC01939A

2016

Visible Light Mediated Metal-Free Thiol–Yne Click Reaction
Chemical Science 2016, 7, 6740–6745. DOI: 10.1039/C6SC02132H