Luminescent cyclometalated iridium(III) polypyridine indole complexes--synthesis, photophysics, electrochemistry, protein-binding properties, cytotoxicity, and cellular uptake
| ISSN: | 1520-510X |
|---|---|
| Přístupová URL adresa: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::454c514d62060c556a318a1ce5810f5a https://pubmed.ncbi.nlm.nih.gov/19099443 |
| Přírůstkové číslo: | edsair.doi.dedup.....454c514d62060c556a318a1ce5810f5a |
| Autor: | Pui-Kei Lee, Cyrus Ho-Cheong Ng, Shuk Han Cheng, Jason Lau, Kenneth Kam-Wing Lo, Keith Hing-Kit Tsang, Yun Wah Lam |
| Rok vydání: | 2008 |
| Předmět: |
Indoles
Luminescence Stereochemistry Polymers Pyridines chemistry.chemical_element Electrons Iridium Medicinal chemistry Absorption Inorganic Chemistry chemistry.chemical_compound Bipyridine Bromide Pyridine Electrochemistry Organometallic Compounds Animals Humans Physical and Theoretical Chemistry Bovine serum albumin Diimine Indole test Microscopy Confocal biology Titrimetry Serum Albumin Bovine Flow Cytometry chemistry Lipophilicity biology.protein Cattle HeLa Cells Protein Binding |
| Zdroj: | Inorganic chemistry. 48(2) |
| ISSN: | 1520-510X |
| Popis: | A series of luminescent cyclometalated iridium(III) polypyridine indole complexes, [Ir(N--C)(2)(N--N)](PF(6)) (HN--C = 2-phenylpyridine (Hppy), N--N = 4-((2-(indol-3-yl)ethyl)aminocarbonyl)-4'-methyl-2,2'-bipyridine (bpy-ind) (1a), N--N = 4-((5-((2-(indol-3-yl)ethyl)aminocarbonyl)pentyl)aminocarbonyl)-4'-methyl-2,2'-bipyridine (bpy-C6-ind) (1b); HN--C = 7,8-benzoquinoline (Hbzq), N--N = bpy-ind (2a), N--N = bpy-C6-ind (2b); and HN--C = 2-phenylquinoline (Hpq), N--N = bpy-ind (3a), N--N = bpy-C6-ind (3b)), have been synthesized, characterized, and their photophysical and electrochemical properties and lipophilicity investigated. Photoexcitation of the complexes in fluid solutions at 298 K and in alcohol glass at 77 K resulted in intense and long-lived luminescence (lambda(em) = 540-616 nm, tau(o) = 0.13-5.15 mus). The emission of the complexes has been assigned to a triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ir) --> pi*(N--N)) excited state, probably with some mixing of triplet intraligand ((3)IL) (pi --> pi*) (pq) character for complexes 3a,b. Electrochemical measurements revealed that all the complexes showed an irreversible indole oxidation wave at ca. +1.1 V versus SCE, a quasi-reversible iridium(IV/III) couple at ca. +1.3 V, and a reversible diimine reduction couple at ca. -1.3 V. The interactions of these complexes with an indole-binding protein, bovine serum albumin (BSA), have been studied by emission titrations, and the K(a) values are on the order of 10(4) M(-1). Additionally, the cytotoxicity of the complexes toward human cervix epithelioid carcinoma (HeLa) cells has been examined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. The IC(50) values of the complexes ranged from 1.1 to 6.3 microM, which are significantly smaller than that of cisplatin (30.7 microM) under the same experimental conditions. Furthermore, the cellular uptake of the complexes has been investigated by flow cytometry and laser-scanning confocal microscopy. The microscopy images indicated that complex 3a was localized in the perinuclear region upon interiorization. Temperature-dependence experiments suggested that the internalization of the complex was an energy-requiring process such as endocytosis. This has been confirmed by cellular-uptake experiments involving the luminescent conjugates Ir-BSA and Ir-TF (TF = holo-transferrin), which were prepared by conjugation of the proteins with the complex [Ir(pq)(2)(phen-NCS)](PF(6)) (phen-NCS = 5-isothiocyanato-1,10-phenanthroline). |
| Databáze: | OpenAIRE |
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