# Photophysical Properties of a Mn(I) Tricarbonyl PhotoCORM With 8‐Aminoquinoline Ligand: Insights From Theory

## TL;DR

This paper uses computational methods to study how a manganese-based compound releases carbon monoxide when exposed to light, which could help in developing cancer treatments.

## Contribution

The study provides a detailed computational framework for understanding CO photorelease mechanisms in Mn(I)-based photoCORMs.

## Key findings

- Mn–CO bonds follow the Dewar–Chatt–Duncanson model with minor solvent effects.
- CO photorelease occurs through triplet metal-centered states, especially in polar solvents.
- Computational methods accurately reproduce UV–vis spectra and identify MLCT states as dominant.

## Abstract

The photophysical properties of a recently synthesized photoCORM, the Mn(I) tricarbonyl complex fac‐[MnBr(CO)3(AQ)] (AQ = 8‐aminoquinoline), with promising cytotoxic activity against triple‐negative breast cancer, have been investigated by means of density functional theory (DFT) and time‐dependent DFT calculations. Simulations in various solvents (water, DMSO, THF) confirmed the Mn–CO bonds follow a Dewar–Chatt–Duncanson model, only slightly modulated by solvent polarity. The optimized computational method accurately reproduced the UV–vis spectrum, identifying the lowest energy excitations as metal‐to‐ligand charge‐transfer (MLCT) states with minor ligand‐to‐ligand charge‐transfer (LLCT) contributions, whose extent depends on solvent polarity. Exploration of the triplet excited‐state manifold revealed several low‐lying metal‐centered (3MC) states accessible from the initial singlet. High spin–orbit coupling and rapid intersystem crossing rates indicate that CO photorelease occurs through efficient population of these dissociative 3MC states, especially in polar media. These findings provide mechanistic insight into the photoactivation pathway of Mn(I)‐based photoCORMs and establish a robust computational framework for designing efficient CO‐releasing therapeutic agents.

The computation of the photophysical properties of the Mn(I) fac‐[MnBr(CO)3(AQ)] photoCORM shows how different solvents can influence structural and light‐triggered behavior for CO molecules release, very likely occurring from triplet states with MC character.