Structure, photophysical and electrochemical properties, biomolecular interactions, and intracellular uptake of luminescent cyclometalated iridium(III) dipyridoquinoxaline complexes

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Kenneth Yin Zhang
  • Steve Po-Yam Li
  • Nianyong Zhu
  • Lyana Wai-Shan Or
  • Maggie Shau-Ha Cheung

Detail(s)

Original languageEnglish
Pages (from-to)2530-2540
Journal / PublicationInorganic Chemistry
Volume49
Issue number5
Publication statusPublished - 1 Mar 2010

Abstract

A series of luminescent cyclometalated iridium(III) dipyrldoquinoxallne complexes [Ir(NC)2(NN)](PF 6) (HNC = 1-phenylpyrazole, Hppz, NN = dipyrido[3,2-f:2′,3′-h]quinoxaline, dpq (1a), 2-(n-butylamido) dlpyrido[3,2-f:2′,3′-h]quinoxallne, dpqa (1b); HNC = 7,8-benzoqulnoline, Hbzq, NN = dpq (2a), dpqa (2b); HN C = 2-phenylqulnoline, Hpq, NN = dpq (3a), dpqa (3b)) has been synthesized and characterized. Cyclic voltammetric studies revealed a reversible or quasi-reversible iridium(IV/III) oxidation couple at about +1.13 to +1.32 V and a reversible diimine reduction couple at about -1.10 to -1.29 V versus SCE. Upon photoexcitation, all the complexes displayed Intense and long-lived green to orange triplet metal-to-ligand charge-transfer ( 3MLCT) (dπ(Ir) -9π*(dpq or dpqa)) emission In aprotlc organic solvents at room temperature and in low-temperature glass. In aqueous solution, these complexes were only weakly emissive or even nonemissive. The lipophilicity of all the complexes has been determined by reversed-phase HPLC. The cytotoxicity of these iridium(III) complexes toward the human cervix epithelioid carcinoma (HeLa) and Madin-Darby canine kidney (MDCK) cell lines has been evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. The cellular uptake of the complexes by MDCK cells has been examined by laserscanning confocal microscopy. Most importantly, apparent nucleolar staining was observed after the cells were treated by the complexes. The interactions of these complexes with proteins, DNA, and RNA have also been studied by emission titrations and SDS-PAGE gel staining. The results revealed that the complexes bound to the hydrophobic pockets of proteins, intercalated into the base-pairs of double-stranded DNA, but did not appear to interact with RNA. ©2010 American Chemical Society.

Citation Format(s)

Structure, photophysical and electrochemical properties, biomolecular interactions, and intracellular uptake of luminescent cyclometalated iridium(III) dipyridoquinoxaline complexes. / Zhang, Kenneth Yin; Li, Steve Po-Yam; Zhu, Nianyong; Or, Lyana Wai-Shan; Cheung, Maggie Shau-Ha; Lam, Yun-Wah; Lo, Kenneth Kam-Wing.

In: Inorganic Chemistry, Vol. 49, No. 5, 01.03.2010, p. 2530-2540.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review