Heteroleptic Ir(III)N₆ Complexes with Long-Lived Triplet Excited States and in Vitro Photobiological Activities

Abstract

A series of cationic heteroleptic iridium(III) complexes bearing tris-diimine ligands [Ir(phen) 2 (Rphen)] 3+ (R-phen = phenanthroline (1), 3,8-diphenylphenanthroline (2), 3,8dipyrenylphenanthroline (3), 3-phenylphenanthroline (4), 3-pyrenylphenanthroline (5), and 3,8diphenylethynylphenanthroline (6)) were synthesized and characterized. These complexes possessed phen ligand-localized 1 π,π* transitions below 300 nm, and charge transfer ( 1 CT) and/or 1 π,π* transitions between 300 and 520 nm. In 1, 2, 4, and 6, the low-energy bands were mixed 1 CT/ 1 π,π*. However, the increased π-donating ability of the pyrenyl substituent(s) in 3 and 5 split the low-energy bands into a pyrene-based 1 π,π* transition at 300-380 nm and an intraligand charge transfer ( 1 ILCT) transition at 380-520 nm. All complexes were emissive at room temperature in CH 3 CN, but the parentage of the emitting state varied depending on the R substituent(s). Complex 1 exhibited predominantly phen ligand-localized 3 π,π* emission mixed with metal-to-ligand charge transfer ( 3 MLCT) character, while the emission of 2, 4, and 6 was predominantly from the excited-state with 3 π,π*/ 3 ILCT/ 3 MLCT character. The emission from 3 and 5 was dominated by pyrene-based 3 π,π* states mixed with 3 ILCT character. The different natures of the lowest triplet excited states were also reflected by the different spectral features and *

Synthesis and Characterization of Ru(II) Complexes with π‐Expansive Imidazophen Ligands for the Photokilling of Human Melanoma Cells

“…Finally, Ru(II) complex 4 was eluted as an orange band with 5-10% H 2 O and 0.5-2.5% KNO 3 in MeCN to give an orange solid as a mixture of Cland NO 3 salts. This mixture was converted to the PF 6 salt by adding 5-10 mL of water and 2-4 mL of saturated KPF 6 Cell assays for dark and phototoxicity. Solutions of the Ru(II) complexes were prepared as follows: 5 mM stock solutions of the Ru(II) chloride complexes were prepared in 10% DMSO-H 2 O and stored at À 20°C prior to use.…”

X-ray tomography of cryopreserved human prostate cancer cells: mitochondrial targeting by an organoiridium photosensitiser

“…Cyclometallated organoiridium(III) octahedral complexes are promising photosensitisers for PDT [12][13][14][15][16][17][18][19][20][21][22]. They possess high photostability and long luminescence lifetimes, together with an ability to permeate cells [23], and generate toxic ROS upon irradiation.…”

Cu(i) diimine complexes as immobilised antibacterial photosensitisers operating in water under visible light

“…101 Ir(III) tris-diimine complexes of the structure [Ir(phen) 2 (R-phen)] 3+ , where R-phen = 3,8-dipyrenylphenanthroline and 3-pyrenylphenanthroline, caused 50% killing of S. aureus at 0.17 and 0.16 mM respectively when irradiated with visible light to a dose of 35 J cm À2 . 23 [Ru(bpy-TMEDA) 3 ] 8+ , 15 mM, achieved a 6.87 log 10 reduction of S. aureus in PBS buffer after 20 min of irradiation at 470 nm, 22 mW cm À2 for a total dose of 27 J cm À2 . 102 Whilst some of these transition metal photosensitisers are very efficient in killing of bacteria, all of the above systems have been studied in solution and therefore cannot be compared directly to 1-silica.…”

“…Currently-used photosensitisers include organic compounds 9,10 (which usually possess nanosecond excited-state lifetimes), porphyrins, and complexes of the 2nd and 3rd row transition metals (including Ir, Ru, Pt, Pd and Os) [12][13][14][15][16][17][18][19][20][21][22][23] which are either rare, expensive, or both. More accessible alternatives are therefore beginning to be developed as photosensitisers.…”