Excited-State Dynamics of Photoisomerization Processes

Photoisomerisation describes the light-induced rearrangement of molecular geometry that underpins key phenomena such as vision, photoswitchable materials and molecular machines. Upon photon absorption, a chromophore is promoted to an electronically excited state, where the interplay of nuclear motion and electronic structure determines the isomerisation pathway. Excited-state potential energy surfaces guide the system through conical intersections, enabling ultrafast nonadiabatic transitions back to the ground state. The temporal evolution of state populations, spanning femtoseconds to picoseconds, dictates quantum yields and product distributions. Advances in ultrafast spectroscopic techniques and ab initio molecular dynamics have elucidated the role of specific vibrational modes in steering reaction coordinates, and have shown how solvent polarity and molecular substituents modulate energy barriers. These insights have profound implications for optimising solar energy capture, refining the design of photoswitches for biomedical applications and controlling enantioselective outcomes under chiral light excitation.

Research from Nature Portfolio

Recent studies have demonstrated that certain molecules, although achiral in their ground state, acquire electronic prochirality upon excitation, enabling asymmetric photoisomerisation without chiral auxiliaries. Investigations of stilbene derivatives revealed that excitation reshapes the excited-state topography to favour unidirectional rotation around double bonds under circularly polarised light. This mechanism offers a new strategy for enantioselective photochemistry, with potential applications in the stereocontrolled synthesis of pharmaceuticals and advanced functional materials.

Excited-State Dynamics of Photoisomerization Processes publication trend

The graph below shows the total number of articles in excited-state dynamics of photoisomerization processes across all publications each year (not limited to Nature Index journals).

Technical terms

Excited state: An electronic configuration of a molecule with higher energy than the ground state, achieved upon photon absorption.

Photoisomerisation: Light-induced rearrangement of molecular structure, often involving rotation around double bonds.

Conical intersection: A point of degeneracy between electronic states where nonadiabatic transitions enable rapid internal conversion.

Nonadiabatic dynamics: Coupled nuclear and electronic motion allowing transitions between electronic states during molecular evolution.

Potential energy surface: A multidimensional landscape representing the energy of a molecule as a function of nuclear coordinates for each electronic state.

Quantum yield: The efficiency of a photochemical process, defined as the number of reactive events per photon absorbed.

References

1. Sensitivity Analysis in Photodynamics: How Does the Electronic Structure Control cis-Stilbene Photodynamics?. Journal of Chemical Theory and Computation (2024).
2. Chiral photochemistry of achiral molecules. Nature Communications (2022).
3. Two phases of trans -stilbene in a polystyrene matrix. Physical Chemistry Chemical Physics (2023).
4. Monitoring the photochemistry of a formazan over 15 orders of magnitude in time. Frontiers in Chemistry (2022).