Abstract
We report new ruthenium complexes bearing the lipophilic bathophenanthroline (BPhen) ligand and dihydroxybipyridine (dhbp) ligands which differ in the placement of the OH groups ([(BPhen)2Ru(n,n′-dhbp)]Cl2 with n = 6 and 4 in 1A and 2A, respectively). Full characterization data are reported for 1A and 2A and single crystal X-ray diffraction for 1A. Both 1A and 2A are diprotic acids. We have studied 1A, 1B, 2A, and 2B (B = deprotonated forms) by UV-vis spectroscopy and 1 photodissociates, but 2 is light stable. Luminescence studies reveal that the basic forms have lower energy 3MLCT states relative to the acidic forms. Complexes 1A and 2A produce singlet oxygen with quantum yields of 0.05 and 0.68, respectively, in acetonitrile. Complexes 1 and 2 are both photocytotoxic toward breast cancer cells, with complex 2 showing EC50 light values as low as 0.50 μM with PI values as high as >200 vs. MCF7. Computational studies were used to predict the energies of the 3MLCT and 3MC states. An inaccessible 3MC state for 2B suggests a rationale for why photodissociation does not occur with the 4,4′-dhbp ligand. Low dark toxicity combined with an accessible 3MLCT state for 1O2 generation explains the excellent photocytotoxicity of 2.
| Original language | English |
|---|---|
| Pages (from-to) | 102-116 |
| Number of pages | 15 |
| Journal | Photochemistry and Photobiology |
| Volume | 98 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 1 2022 |
| Externally published | Yes |
Funding
We gratefully acknowledge support from the NIH (R15‐GM132803‐01) to ETP and YK and the NSF (CHE 1800201 and 2102552) to CEW. Preliminary studies were also supported by the Research Grants Committee (RGC) at UA to ETP and YK. SRB was supported by the US Department of Education as a GAANN Teaching Fellow (P200A180056). We acknowledge Juliana Bates, Nicholas Belt and Yifei Sun for their technical assistance in cell studies. We thank NSF MRI program (CHE 1726812, PI Cassady) and UA for the purchase of a MALDI TOF/TOF MS and Dr. Qiaoli Liang for MS experimental work. We thank Dr. Ken Belmore for assistance with the NMR experiments. We thank NSF CHE MRI 1828078 (PI Papish) and UA for the purchase of the SC XRD instrument. We thank NSF CHE MRI 1919906 (PI Rupar) and UA for the purchase of an NMR spectrometer. The computational work was completed with resources provided by the Mississippi State University High Performance Computing Collaboratory, the Mississippi Center for Supercomputing Research, and the Alabama Supercomputer Authority. SAM and CGC thank the National Cancer Institute (NCI) of the National Institutes of Health (NIH) (Award R01CA222227) for support in part of this work. The content in this paper is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. We gratefully acknowledge support from the NIH (R15-GM132803-01) to ETP and YK and the NSF (CHE 1800201 and 2102552) to CEW. Preliminary studies were also supported by the Research Grants Committee (RGC) at UA to ETP and YK. SRB was supported by the US Department of Education as a GAANN Teaching Fellow (P200A180056). We acknowledge Juliana Bates, Nicholas Belt and Yifei Sun for their technical assistance in cell studies. We thank NSF MRI program (CHE 1726812, PI Cassady) and UA for the purchase of a MALDI TOF/TOF MS and Dr. Qiaoli Liang for MS experimental work. We thank Dr. Ken Belmore for assistance with the NMR experiments. We thank NSF CHE MRI 1828078 (PI Papish) and UA for the purchase of the SC XRD instrument. We thank NSF CHE MRI 1919906 (PI Rupar) and UA for the purchase of an NMR spectrometer. The computational work was completed with resources provided by the Mississippi State University High Performance Computing Collaboratory, the Mississippi Center for Supercomputing Research, and the Alabama Supercomputer Authority. SAM and CGC thank the National Cancer Institute (NCI) of the National Institutes of Health (NIH) (Award R01CA222227) for support in part of this work. The content in this paper is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.