Photochemical Properties of Red-Emitting Tris(cyclometalated) Iridium(III) Complexes Having Basic and Nitro Groups and Application to pH Sensing and Photoinduced Cell Death.

Cyclometalated iridium(III) complexes, because of their photophysical properties, have the potential for use as luminescent probes for cellular imaging. We previously reported on a pH-activatable iridium complex that contains three N,N-diethylamino groups, namely, fac-Ir(deatpy)3 5, which was synthesized via a regioselective aromatic substitution reaction at the 5'-position with tolylpyridine groups of fac-Ir(tpy)3 2. It was found that 5 shows a considerable enhancement in emission intensity in the pH range from neutral to slightly acidic (pH 6.

Synthesis and photochemical properties of pH responsive tris-cyclometalated iridium(III) complexes that contain a pyridine ring on the 2-phenylpyridine ligand.

In our previous publication, it was reported that fac-Ir(atpy)3 3 (atpy = 2-(5'-amino-4'-tolyl)pyridine), which contains three amino groups at the 5'-position of the atpy ligands, exhibits a pH-dependent change in the color of the emitted radiation. Aqueous solution of 3 shows a weak red emission (at around 613 nm) under neutral or basic conditions, but the emission color changes to green (at around 530 nm) under acidic conditions, where the NH2 group is protonated to become an electron-withdrawing (NH3)(+) group. In this manuscript, we report on the preparation of some new pH-responsive Ir(III) complexes; fac-Ir(4Pyppy)3 5 and fac-Ir(3Pyppy)3 6 that contain three pyridyl groups at the 5'-position of the 2-phenylpyridine (ppy) ligand, and Ir(4Pyppym)3 7 and Ir(3Pyppym)3 8 that contain a pyridyl group at the same position of the 2-phenylpyrimidine (ppym) ligand.

Design and synthesis of a luminescent cyclometalated iridium(III) complex having N,N-diethylamino group that stains acidic intracellular organelles and induces cell death by photoirradiation.

Cyclometalated iridium(III) complexes have received considerable attention and are important candidates for use as luminescent probes for cellular imaging because of their potential photophysical properties. We previously reported that fac-Ir(atpy)(3)4 (atpy = 2-(5'-amino-4'-tolyl)pyridine) containing three amino groups at the 5'-position of the atpy ligand shows a maximum red emission (at around 600 nm) under neutral and basic conditions and a green emission (at 531 nm) at acidic pH (pH 3-4). In this Article, we report on the design and synthesis of a new pH-sensitive cyclometalated Ir(III) complex containing a 2-(5'-N,N-diethylamino-4'-tolyl)pyridine (deatpy) ligand, fac-Ir(deatpy)(3)5.

Regioselective aromatic substitution reactions of cyclometalated Ir(III) complexes: synthesis and photochemical properties of substituted Ir(III) complexes that exhibit blue, green, and red color luminescence emission.

In this manuscript, the regioselective halogenation, nitration, formylation, and acylation of Ir(tpy)(3) and Ir(ppy)(3) (tpy = 2-(4'-tolyl)pyridine and ppy = 2-phenylpyridine) and the subsequent conversions are described. During attempted bromination of the three methyl groups in fac-Ir(tpy)(3) using N-bromosuccinimide (NBS) and benzoyl peroxide (BPO), three protons at the 5'-position (p-position with respect to the C-Ir bond) of phenyl rings in tpy units were substituted by Br, as confirmed by (1)H NMR spectra, mass spectra, and X-ray crystal structure analysis. It is suggested that such substitution reactions of Ir complexes proceed via an ionic mechanism rather than a radical mechanism.