Reductive quenching of photosensitizer [Ru(bpy)] reveals the inhomogeneous distribution of sites in PAN polymer nanofibers for light-driven redox catalysis.

Integration of molecular photocatalysts into redox-inert polymers constitutes a path towards photocatalytically active, lightweight materials. In particular, electrospun polymer fibers hold potential due to their favorable surface-to-volume ratio and their straightforward fabrication. This study focuses on the polyacrylonitrile (PAN) fibers, into which the prototype photosensitizer (PS) ruthenium tris(bipyridine) [Ru(bpy)], has been embedded by electrospinning. Studying the interaction between the optically excited [Ru(bpy)] with a non-redox inert solvent within the nanofibers, we resolve a distribution of microenvironments, which differ by the extent to which the photosensitizer is exposed to the solvent. This results in a non-exponential decay of the complex's emission and pronounced differences in the transient absorption signals.