Synthesis and Electrochemical, Photophysical, and Self-Assembly Studies on Water-Soluble pH-Responsive Alkynylplatinum(II) Terpyridine Complexes.
A series of water-soluble pH-responsive alkynylplatinum(II) terpyridine complexes have been synthesized and characterized. The electronic absorption, emission, and electrochemical properties of the complexes have been studied. The self-assembly processes of representative complexes in aqueous media, presumably through Pt···Pt and/or π-π interactions, have been investigated by concentration- and temperature-dependent UV-vis absorption measurements and dynamic light scattering experiments. Interestingly, some of the complexes have been found to undergo induced self-assembly and disassembly in aqueous media through modulation of the pH value of the solutions, resulting in remarkable UV-vis absorption and emission spectral changes. The emission spectral changes have been rationalized by the change in the hydrophilicity of the complexes, electrostatic repulsion among the complex molecules, and/or the extent of photoinduced electron transfer (PET) quenching upon protonation/deprotonation of the pH-responsive groups on the complexes. By simple modifications of the chemical structures of the complexes, induced self-assembly/disassembly of the complexes can occur at different and/or multiple pH regions, thus allowing the probing of changes at the desired pH region by triplet metal-metal-to-ligand charge-transfer emission of the complexes in the near-infrared (NIR) region. Fixed-cell imaging experiments have further demonstrated the potential of this class of complexes as pH-responsive NIR luminescent probes in vitro, while the NIR emissions of the complexes from live cells have been found to show good differentiation of acidic organelles such as lysosomes from other cellular compartments.
Institute of Molecular Functional Materials [Areas of Excellence Scheme, University Grants Committee (Hong Kong)] and Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong, P. R. China.
Clive Yik-Sham
CY
Chung
Department of Biology and Chemistry, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, P. R. China.
Steve Po-Yam
SP
Li
Department of Biology and Chemistry, City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong, P. R. China.
Kenneth Kam-Wing
KK
Lo
Institute of Molecular Functional Materials [Areas of Excellence Scheme, University Grants Committee (Hong Kong)] and Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong, P. R. China.
Vivian Wing-Wah
VW
Yam
D000480:Alkynes / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008027:Light; D049408:Luminescent Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D008247:Lysosomes / Q000378:metabolism; D018613:Microscopy, Confocal; D009944:Organoplatinum Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D010084:Oxidation-Reduction; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D012995:Solubility; D014867:Water / Q000737:chemistry
D000480:Alkynes; D049408:Luminescent Agents; D009944:Organoplatinum Compounds; D011725:Pyridines; D014867:Water