TY - JOUR
T1 - Synthesis, Characterization and Photobiological Studies of Ru(II) Dyads Derived from α-Oligothiophene Derivatives of 1,10-Phenanthroline
AU - Monro, Susan
AU - Cameron, Colin G.
AU - Zhu, Xiaolin
AU - Colón, Katsuya L.
AU - Yin, Huimin
AU - Sainuddin, Tariq
AU - Hetu, Marc
AU - Pinto, Mitch
AU - Fuller, Anderson
AU - Bennett, Leah
AU - Roque, John
AU - Sun, Wenfang
AU - McFarland, Sherri A.
N1 - Funding Information:
Acknowledgements—Research reported in this publication was supported by the National Cancer Institute of the National Institutes of Health under Award Number R01CA222227. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. We also acknowledge financial support from the University of North Carolina at Greensboro, the Natural Sciences and Engineering Council of Canada, the Canadian Institutes of Health Research, the Canadian Foundation for Innovation, the Nova Scotia Research and Innovation Trust, and Acadia University.
Publisher Copyright:
© 2018 The American Society of Photobiology
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Three new bis(2,2′-bipyridine)-heteroleptic Ru(II) dyads incorporating thienyl groups (n = 1–3, compounds 1, 2 and 3, respectively) appended to 1,10-phenanthroline were synthesized and characterized to investigate the impact of n on the photophysical and photobiological properties within the series. All three complexes showed unstructured emission near 618 nm from a triplet metal-to-ligand charge transfer ( 3 MLCT) state with a lifetime (τ em ) of approximately 1 μs. Transient absorption measurements revealed an additional excited state that was nonemissive and long-lived (τ TA = 43 μs for 2 and 27 μs for 3), assigned as a triplet intraligand ( 3 IL) state that was accessible only in 2 and 3. All three complexes were strong singlet oxygen ( 1 O 2 ) sensitizers, with quantum yields (Φ ∆ ) for 2 and 3 being the largest (74–78%), and all three were photocytotoxic to cancer cells with visible light activation in the order: 3 > 2 > 1. Cell-free DNA photodamage followed the same trend, where potency increased with decreasing 3 IL energy. Compounds 2 and 3 also showed in vitro photobiological effects with red light (625 nm), where their molar absorptivities were <100 m −1 cm −1 . These findings highlight that Ru(II) dyads derived from α-oligothiophenes directly appended to 1,10-phenanthroline—namely 2 and 3—possess low-lying 3 IL states that are highly photosensitizing, and they may therefore be of interest for photobiological applications such as photodynamic therapy (PDT).
AB - Three new bis(2,2′-bipyridine)-heteroleptic Ru(II) dyads incorporating thienyl groups (n = 1–3, compounds 1, 2 and 3, respectively) appended to 1,10-phenanthroline were synthesized and characterized to investigate the impact of n on the photophysical and photobiological properties within the series. All three complexes showed unstructured emission near 618 nm from a triplet metal-to-ligand charge transfer ( 3 MLCT) state with a lifetime (τ em ) of approximately 1 μs. Transient absorption measurements revealed an additional excited state that was nonemissive and long-lived (τ TA = 43 μs for 2 and 27 μs for 3), assigned as a triplet intraligand ( 3 IL) state that was accessible only in 2 and 3. All three complexes were strong singlet oxygen ( 1 O 2 ) sensitizers, with quantum yields (Φ ∆ ) for 2 and 3 being the largest (74–78%), and all three were photocytotoxic to cancer cells with visible light activation in the order: 3 > 2 > 1. Cell-free DNA photodamage followed the same trend, where potency increased with decreasing 3 IL energy. Compounds 2 and 3 also showed in vitro photobiological effects with red light (625 nm), where their molar absorptivities were <100 m −1 cm −1 . These findings highlight that Ru(II) dyads derived from α-oligothiophenes directly appended to 1,10-phenanthroline—namely 2 and 3—possess low-lying 3 IL states that are highly photosensitizing, and they may therefore be of interest for photobiological applications such as photodynamic therapy (PDT).
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U2 - 10.1111/php.13012
DO - 10.1111/php.13012
M3 - Article
C2 - 30193398
AN - SCOPUS:85055573084
SN - 0031-8655
VL - 95
SP - 267
EP - 279
JO - Photochemistry and Photobiology
JF - Photochemistry and Photobiology
IS - 1
ER -