Reactions of Cyclometalated Platinum(II) [Pt(N∧C)(PR3)Cl] Complexes with Imidazole and Imidazole-Containing Biomolecules: Fine-Tuning of Reactivity and Photophysical Properties via Ligand Design

Анастасия Игоревна Соломатина, Павел Сергеевич Челушкин, Татьяна О. Абакумова, Владимир А. Жемков, Mee-Whi Kim, Ilya Bezprozvanny, Владислав Владимирович Гуржий, Алексей Сергеевич Мельников, Юрий Алексеевич Ануфриков, Игорь Олегович Кошевой, Shih Hao Su, Pi-Tai Chou, Сергей Павлович Туник

Research output

4 Citations (Scopus)

Abstract

This work describes interaction of a family of [Pt(N C)(PR 3 )Cl] complexes with imidazole (Im), possible application of this chemistry for regioselective labeling of proteins through imidazole rings of histidine residues and employment of the resulting phosphorescent products in bioimaging. It was found that the complexes containing aliphatic phosphines display reversible substitution of chloride ligand for imidazole function that required considerable excess of imidazole to obtain full conversion into the substituted [Pt(ppy)(PR 3 )(Im)] product, whereas the substitution in the complexes with aromatic phosphines readily proceeds in 1:1.5 mixture of reagents. Rapid, selective, and quantitative coordination of imidazole to the platinum complexes enabled regioselective labeling of ubiquitin. X-ray protein crystallography of the {[Pt(ppy)(PPh 3 )]/ubiquitin} conjugate revealed direct bonding of the platinum center to unique histidine-68 residue through the nitrogen atom of imidazole function, the coordination being also supported by noncovalent interaction of the ligands with the protein secondary structure. The variations of the cyclometalating N C ligands gave a series of [Pt(N C)(PPh 3 )Cl] complexes (N C = 2-phenylpyridine, 2-(benzofuran-3-yl)pyridine, 2-(benzo[b]thiophen-3-yl)pyridine, methyl-2-phenylquinoline-4-carboxylate), which were used to investigate the impact of N C-ligand onto photophysical properties of the imidazole complexes and conjugates with human serum albumin (HSA). The chloride ligand substitution for imidazole and formation of the conjugates results in ignition of the platinum chromophore luminescence with substantially higher quantum yield in the latter case. Variation of the metalating N C-ligand made possible the shift of the emission to the red region of visible spectrum for both types of the products. Cell-viability tests revealed low cytotoxicity of all {[Pt(N C)(PPh 3 )Cl]/HSA} conjugates, while PLIM experiments demonstrated their high potential for oxygen sensing.

Original languageEnglish
Pages (from-to)204-217
Number of pages14
JournalInorganic Chemistry
Volume58
Issue number1
DOIs
Publication statusPublished - 7 Jan 2019

Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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