A series of five ruthenium complexes containing triphenyl phosphine groups known to enhance both cellular penetration and photoinduced ligand exchange, cis -[Ru(bpy) 2 (P( p -R-Ph) 3 )(CH 3 CN)] 2+ , where bpy = 2,2′-bipyridine and P( p -R-Ph) 3 represent para -substituted triphenylphosphine ligands with R = –OCH 3 (1), –CH 3 (2) –H (3), –F (4), and –CF 3 (5), were synthesized and characterized. The photolysis of 1–5 in water with visible light ( λ irr ≥ 395 nm) results in the substitution of the coordinated acetonitrile with a solvent molecule, generating the corresponding aqua complex as the single photoproduct. A 3-fold variation in quantum yield was measured with 400 nm irradiation, Φ 400 , where 1 is the most efficient with a Φ 400 = 0.076(2), and 5 the least photoactive complex, with Φ 400 = 0.026(2). This trend is unexpected based on the red-shifted metal-to-ligand charge transfer (MLCT) absorption of 1 as compared to that of 5, but can be correlated to the substituent Hammett para parameters and p K a values of the ancillary phosphine ligands. Complexes 1–5 are not toxic towards the triple negative breast cancer cell line MDA-MB-231 in the dark, but 3 and 5 are >4.2 and >19-fold more cytotoxic upon irradiation with blue light, respectively. A number of experiments point to apoptosis, and not to necrosis or necroptosis, as the mechanism of cell death by 5 upon irradiation. These findings provide a foundation for understanding the role of phosphine ligands on photoinduced ligand substitution and show the enhancement afforded by –CF 3 groups on photochemotherapy, which will aid the future design of photocages for photochemotherapeutic drug delivery.
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Phosphorescent 2-, 3- and 4-coordinate cyclic (alkyl)(amino)carbene (CAAC) Cu( i ) complexes
The photophysical properties of several Cu( i ) complexes coordinated with cyclic (alkyl)(amino)carbene (CAAC) ligands were examined. All the compounds were found to be phosphorescent, regardless of whether they are 2-, 3- or 4-coordinated. Aggregate and excimer emission were observed from 2-coordinate CAAC–CuCl derivatives in methylcyclohexane solution. Emission from the complex 4-coordinated with a trispyrazolylborate ligand is red-shifted with respect to both the chloro-derivative and an analogous complex with an NHC ligand.
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- Award ID(s):
- 1661518
- NSF-PAR ID:
- 10056652
- Date Published:
- Journal Name:
- Chemical Communications
- Volume:
- 53
- Issue:
- 64
- ISSN:
- 1359-7345
- Page Range / eLocation ID:
- 9008 to 9011
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/c7cc02638b
