TY - JOUR
T1 - Bis-tridentate N-Heterocyclic Carbene Ru(II) Complexes are Promising New Agents for Photodynamic Therapy
AU - Ryan, Raphael T.
AU - Stevens, Kimberly C.
AU - Calabro, Rosemary
AU - Parkin, Sean
AU - Mahmoud, Jumanah
AU - Kim, Doo Young
AU - Heidary, David K.
AU - Glazer, Edith C.
AU - Selegue, John P.
N1 - Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/7/6
Y1 - 2020/7/6
N2 - Ruthenium(II) complexes developed for photodynamic therapy (PDT) are almost exclusively tris-bidentate systems with C2 or D3 symmetry. This is due to the fact that this structural framework commonly produces long-lived excited states, which, in turn, allow for the generation of large amounts of singlet oxygen (1O2) and other reactive oxygen species. Complexes containing tridentate ligands would be advantageous for biological applications as they are generally achiral (D2d or C2v symmetry), which eliminates the possibility of multiple isomers which could exhibit potentially different interactions with chiral biological entities. However, Ru(II) complexes containing tridentate ligands are rarely studied as candidates for photobiological applications, such as PDT, since they almost exclusively exhibit low quantum yields and very short excited-state lifetimes and, thus, are not capable of generating sufficient 1O2 or engaging in electron transfer reactions. Here, we report a proof-of-concept approach to make bis-tridentate Ru(II) complexes useful for PDT applications by altering their photophysical properties through the inclusion of N-heterocyclic carbene (NHC) ligands. Three NHC and two terpyridine ligands were studied to evaluate the effects of structural and photophysical modulations of bis-substituted Ru(II) complexes. The NHC complexes were found to have superior excited-state lifetimes, 1O2 production, and photocytotoxicity. To the best of our knowledge, these complexes are the most potent light-activated bis-tridentate complexes reported.
AB - Ruthenium(II) complexes developed for photodynamic therapy (PDT) are almost exclusively tris-bidentate systems with C2 or D3 symmetry. This is due to the fact that this structural framework commonly produces long-lived excited states, which, in turn, allow for the generation of large amounts of singlet oxygen (1O2) and other reactive oxygen species. Complexes containing tridentate ligands would be advantageous for biological applications as they are generally achiral (D2d or C2v symmetry), which eliminates the possibility of multiple isomers which could exhibit potentially different interactions with chiral biological entities. However, Ru(II) complexes containing tridentate ligands are rarely studied as candidates for photobiological applications, such as PDT, since they almost exclusively exhibit low quantum yields and very short excited-state lifetimes and, thus, are not capable of generating sufficient 1O2 or engaging in electron transfer reactions. Here, we report a proof-of-concept approach to make bis-tridentate Ru(II) complexes useful for PDT applications by altering their photophysical properties through the inclusion of N-heterocyclic carbene (NHC) ligands. Three NHC and two terpyridine ligands were studied to evaluate the effects of structural and photophysical modulations of bis-substituted Ru(II) complexes. The NHC complexes were found to have superior excited-state lifetimes, 1O2 production, and photocytotoxicity. To the best of our knowledge, these complexes are the most potent light-activated bis-tridentate complexes reported.
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U2 - 10.1021/acs.inorgchem.0c00686
DO - 10.1021/acs.inorgchem.0c00686
M3 - Article
C2 - 32530274
AN - SCOPUS:85086713274
SN - 0020-1669
VL - 59
SP - 8882
EP - 8892
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 13
ER -