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Title: Photophysical and Photobiological Properties of Dinuclear Iridium(III) Bis-tridentate Complexes

Abstract

A series of cationic dinuclear iridium(III) complexes (Ir1–Ir5) bearing terpyridine-capped fluorenyl bridging ligands and different polypyridyl or cyclometalating terminal tridentate ligands were synthesized, characterized, and evaluated for their photophysical and photobiological activities. The influence of the bridging and terminal ligands on the photophysical properties of the complexes was investigated by UV–vis absorption, emission, and transient absorption spectroscopy and simulated by TDDFT calculations. All of the complexes displayed strong bridging-ligand localized visible 1π,π* absorption and red- or near-infrared phosphorescence as well as broad triplet excited-state absorption across both visible and NIR wavelengths. These triplet states were assigned as predominantly 3π,π* for Ir1 (τ = 3.1 μs) and Ir4 (τ = 48 μs) and 3CT (charge transfer) for Ir2, Ir3, and Ir5 (τ = 1.7–2.7 μs). Complexes Ir1–Ir5 acted as in vitro photodynamic therapy (PDT) agents toward human SK-MEL-28 melanoma cells when activated with visible light, with submicromolar photocytotoxicity and phototherapeutic indices ranging from 20 to almost 300. The in vitro PDT effects with visible light did not correlate with singlet oxygen (1O2) quantum yields or DNA photocleaving capacity probed under cell-free conditions. All of the Ir(III) complexes phosphoresced brightly when associated with compromised cells (with or without light treatment) and exhibitedmore » photoactivated cellular uptake, highlighting the theranostic potential of this new class of Ir(III) complex photosensitizers.« less

Authors:
 [1];  [2];  [1];  [3];  [3];  [2]; ORCiD logo [1]; ORCiD logo [4]; ORCiD logo [1]
  1. North Dakota State Univ., Fargo, ND (United States)
  2. Acadia Univ., Wolfville, NS (Canada)
  3. Univ. of North Carolina, Greensboro, NC (United States)
  4. Acadia Univ., Wolfville, NS (Canada); Univ. of North Carolina, Greensboro, NC (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Univ. of California, Oakland, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1543620
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 57; Journal Issue: 16; Journal ID: ISSN 0020-1669
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Chemistry

Citation Formats

Liu, Bingqing, Monro, Susan, Lystrom, Levi, Cameron, Colin G., Colón, Katsuya, Yin, Huimin, Kilina, Svetlana, McFarland, Sherri A., and Sun, Wenfang. Photophysical and Photobiological Properties of Dinuclear Iridium(III) Bis-tridentate Complexes. United States: N. p., 2018. Web. doi:10.1021/acs.inorgchem.8b00789.
Liu, Bingqing, Monro, Susan, Lystrom, Levi, Cameron, Colin G., Colón, Katsuya, Yin, Huimin, Kilina, Svetlana, McFarland, Sherri A., & Sun, Wenfang. Photophysical and Photobiological Properties of Dinuclear Iridium(III) Bis-tridentate Complexes. United States. doi:10.1021/acs.inorgchem.8b00789.
Liu, Bingqing, Monro, Susan, Lystrom, Levi, Cameron, Colin G., Colón, Katsuya, Yin, Huimin, Kilina, Svetlana, McFarland, Sherri A., and Sun, Wenfang. Mon . "Photophysical and Photobiological Properties of Dinuclear Iridium(III) Bis-tridentate Complexes". United States. doi:10.1021/acs.inorgchem.8b00789. https://www.osti.gov/servlets/purl/1543620.
@article{osti_1543620,
title = {Photophysical and Photobiological Properties of Dinuclear Iridium(III) Bis-tridentate Complexes},
author = {Liu, Bingqing and Monro, Susan and Lystrom, Levi and Cameron, Colin G. and Colón, Katsuya and Yin, Huimin and Kilina, Svetlana and McFarland, Sherri A. and Sun, Wenfang},
abstractNote = {A series of cationic dinuclear iridium(III) complexes (Ir1–Ir5) bearing terpyridine-capped fluorenyl bridging ligands and different polypyridyl or cyclometalating terminal tridentate ligands were synthesized, characterized, and evaluated for their photophysical and photobiological activities. The influence of the bridging and terminal ligands on the photophysical properties of the complexes was investigated by UV–vis absorption, emission, and transient absorption spectroscopy and simulated by TDDFT calculations. All of the complexes displayed strong bridging-ligand localized visible 1π,π* absorption and red- or near-infrared phosphorescence as well as broad triplet excited-state absorption across both visible and NIR wavelengths. These triplet states were assigned as predominantly 3π,π* for Ir1 (τ = 3.1 μs) and Ir4 (τ = 48 μs) and 3CT (charge transfer) for Ir2, Ir3, and Ir5 (τ = 1.7–2.7 μs). Complexes Ir1–Ir5 acted as in vitro photodynamic therapy (PDT) agents toward human SK-MEL-28 melanoma cells when activated with visible light, with submicromolar photocytotoxicity and phototherapeutic indices ranging from 20 to almost 300. The in vitro PDT effects with visible light did not correlate with singlet oxygen (1O2) quantum yields or DNA photocleaving capacity probed under cell-free conditions. All of the Ir(III) complexes phosphoresced brightly when associated with compromised cells (with or without light treatment) and exhibited photoactivated cellular uptake, highlighting the theranostic potential of this new class of Ir(III) complex photosensitizers.},
doi = {10.1021/acs.inorgchem.8b00789},
journal = {Inorganic Chemistry},
issn = {0020-1669},
number = 16,
volume = 57,
place = {United States},
year = {2018},
month = {4}
}

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