Excited-state dynamics of [Mn(im)(CO)₃(phen)]⁺: PhotoCORM, catalyst, luminescent probe?

Mn(I) α-diimine carbonyl complexes have shown promise in the development of luminescent CO release materials (photoCORMs) for diagnostic and medical applications due to their ability balance energy low-lying metal-to-ligand charge transfer (MLCT) metal-centered (MC) states. In this work, excited state dynamics [Mn(im)(CO)3(phen)]+ (im = imidazole; phen 1,10-phenanthroline) is investigated by means wavepacket propagation on potential surfaces associated with 11 Sn singlet states within a vibronic coupling model (quasi)-diabatic representation including 16 nuclear degrees freedom. The results show that early time photophysics (<400 fs) controlled interaction between two MC dissociative states, namely, S5 S11, lowest S1–S3 MLCT bound particular, presence S1/S5 S2/S11 crossings diabatic picture along Mn–COaxial coordinate (qMn–COaxial) favors two-stepwise population at about 60–70 fs (S11) 160–180 (S5), which reaches 10% 200 fs. one-dimensional reduced densities qMn–COaxial as function clearly point concurrent primary processes, vs entrapping into S1 S2 wells 400 fs, characteristics photoCORM.