posted on 2023-12-29, 18:06authored byAndrea Ramundo, Jiří Janoš, Lucie Muchová, Mária Šranková, Jakub Dostál, Miroslav Kloz, Libor Vítek, Petr Slavíček, Petr Klán
We report on porphyrin–flavonol
hybrids consisting of a
porphyrin antenna and four covalently bound 3-hydroxyflavone (flavonol)
groups, which act as highly efficient photoactivatable carbon monoxide
(CO)-releasing molecules (photoCORMs). These bichromophoric systems
enable activation of the UV-absorbing flavonol chromophore by visible
light up to 650 nm and offer precise spatial and temporal control
of CO administration. The physicochemical properties of the porphyrin
antenna system can also be tuned by inserting a metal cation. Our
computational study revealed that the process occurs via endergonic
triplet–triplet energy transfer from porphyrin to flavonol
and may become feasible thanks to flavonol energy stabilization upon
intramolecular proton transfer. This mechanism was also indirectly
supported by steady-state and transient absorption spectroscopy techniques.
Additionally, the porphyrin–flavonol hybrids were found to
be biologically benign. With four flavonol CO donors attached to a
single porphyrin chromophore, high CO release yields, excellent uncaging
cross sections, low toxicity, and CO therapeutic properties, these
photoCORMs offer exceptional potential for their further development
and future biological and medical applications.