A Triphenylphosphonium-Functionalised Cyclometalated Platinum(II) Complex as a Nucleolus-Specific Two-Photon Molecular Dye

Chi Kin Koo, Leo K.Y. So, Ka Leung Wong, Yu Man Ho, Yun Wah Lam, Michael H.W. Lam, Kwok Wai Cheah, Chopen Chan Wut Cheng, Wai Ming Kwok

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An organometallic cyclometalated platinum(II) complex, [Pt(L 3)Cl] [PF6], has been synthesised from a specially designed cyclometalating ligand, HL3 (triphenyl{5-[3-(6- phenylpyridin-2-yl)-l//-pyrazol-1-yl]pentyl}phosphonium chloride), that contains a pendant carbon chain carrying a terminal cationic triphenylphosphonium moiety. Aside from its room temperature single-photon luminescent properties in solution, [Pt(L3)Cl] + can also produce two-photon-induced luminescence at room temperature upon excitation at 700 nm from a mode- locked Ti: sapphire laser. Its twophoton absorption cross-section in DMF at room temperature was measured to be 28.0 x 10-50cm4 s photon-1. [Pt(L3)Cl]+ is able to selectively stain the cell nucleolus. This has been demonstrated by two-photon confocal imaging of live and methanol-fixed HeLa (human cervical carcinoma) and 3T3 (mouse skin fibroblasts) cells. This organelle specificity is likely to be related to its special affinity for proteins within cell nucleoli. As a result of such protein affinity, [Pt(L3)Cl]+ is an efficient RNA transcription inhibitor and shows rather profound cytotoxicity. On the other hand, the organelle-specific labelling and two-photon-induced luminescent properties of [Pt(L3)Cl]+ renders it a useful nuclear dye for the 3-dimensional reconstruction of optical sections of thick tissues, for example, mouse ileum tissues, by multiphoton confocal microscopy.

Original languageEnglish
Pages (from-to)3942-3950
Number of pages9
JournalChemistry - A European Journal
Issue number13
Early online date22 Mar 2010
Publication statusPublished - 6 Apr 2010
Externally publishedYes

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