Palladium(II) Acetylide Complexes with Pincer-Type Ligands: Photophysical Properties, Intermolecular Interactions, and Photo-cytotoxicity

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• 作者：Dr. Faan-Fung Hung ; Dr. Shui-Xing Wu ; Dr. Wai-Pong To ; Dr. Wai-Lun Kwong ; Dr. Xiangguo Guan ; Prof. Dr. Wei Lu ; Dr. Kam-Hung Low and Prof. Dr. Chi-Ming Che
• 刊名：Chemistry – An Asian Journal
• 出版年：2017
• 出版时间：January 3, 2017
• 年：2017
• 卷：12
• 期：1
• 页码：145-158
• 全文大小：2934K
• ISSN：1861-471X

文摘

Two classes of cationic palladium(II) acetylide complexes containing pincer-type ligands, 2,2′:6′,2′′-terpyridine (terpy) and 2,6-bis(1-butylimidazol-2-ylidenyl)pyridine (C^N^C), were prepared and structurally characterized. Replacing terpy with the strongly σ-donating C^N^C ligand with two N-heterocyclic carbene (NHC) units results in the Pd^II acetylide complexes displaying phosphorescence at room temperature and stronger intermolecular interactions in the solid state. X-ray crystal structures of [Pd(terpy)(C≡CPh)]PF₆ (1) and [Pd(C^N^C)(C≡CPh)]PF₆ (7) reveal that the complex cations are arranged in a one-dimensional stacking structure with pair-like Pd^II⋅⋅⋅Pd^II contacts of 3.349 Å for 1 and 3.292 Å for 7. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were used to examine the electronic properties. Comparative studies of the [Pt(L)(C≡CPh)]⁺ analogs by ¹H NMR spectroscopy shed insight on the intermolecular interactions of these Pd^II acetylide complexes. The strong Pd−C_carbene bonds render 7 and its derivative sufficiently stable for investigation of photo-cytotoxicity under cellular conditions.