New luminescent cyclometalated iridium complexes prepared by the post-synthetic modification

作者：Kataoka Yusuke; Okuno Kaede; Yano Natsumi; Ueda Hikaru; Kawamoto Tatsuya; Handa Makoto

来源：Journal of Photochemistry and Photobiology A: Chemistry , 2018, 358: 345-355.

DOI：10.1016/j.jphotochem.2017.09.009

• Cyclometalated iridium complex
• Post-synthetic modification
• Photophysical properties
• Crystal structures
• Photochemical hydrogen evolution

Luminescent heteroleptic bis-cyclometalated iridium(III) complexes, [Ir(PPY)(2)(RPh-phen)](PF6) (Hppy = 2-phenylpyridine; RPh-phen= 5-(4'-R-substituted phenyl)-1,10-phenanthroline, R = H for 3, tBu for 4, and CF3 for 5), have been synthesized via Suzuki-Miyaura cross coupling reaction of the corresponding boronic acids with [Ir(ppy)(2)(X-phen)]Cl (X-phen = 5-halogen-1,10-phenanthroline, X = Cl for 1 and Br for 2) and structurally characterized via single crystal X-ray diffraction analysis. Spectroscopic analyses and density functional calculations revealed that 3-5 in CH2Cl2 show intense orange emission with long emission lifetimes (tau = 708-784 ns) and high quantum yields (Phi=23.6-40.6%) that originate from a T-1 -> S-0 transition from the phen moiety to the Ir(ppy)(2) moiety. Cyclic voltammetry analyses elucidated that 3-5 have reversible 1e(-) reduction and oxidation waves. The photosensitizing properties of 1-5 as well as [Ir(ppy)(2)(phen)](PF6) (6; phen = 1,10-phenanthroline) were also analyzed via Stern-Volmer plots and photoreduction reactions of protons to yield hydrogen (H-2). These results revealed that 3 is a promising photosensitizer for photochemical H-2 evolution reaction that is comparable to 6.

• 出版日期2018-5-1