Highly photostable sensitizers for artificial photosynthesis. Ruthenium(II)-3,3'-bis(diazine)-6,6'-oligo(ethylene glycol) complexes and a new class of podates

Abstract

Absorption spectra, emission spectra (90 and 298 K), luminescence lifetimes, luminescence quantum yields, and photochemical behavior of a semicage bipyridazine (bpdz) Ru(II) complex K6 and related open-chain bpdz model complexes Kl-4 have been studied and compared with those of Ru(bpy)32+ K5. The absorption bands in the visible spectra of Kl-4 and Ru-podate K6 are close in energy to the corresponding bands of Ru(bpy)32+, whereas the emission bands are slightly red shifted. The luminescence lifetimes of K1^4/K6 (1500-3400 ns) are longer than that of K5 (600 ns). The open-chain bpdz model complexes and especially K6 are highly photoinert ( < 10"5) relative to the photodissociation of Ru(bpy)32+ ( = 0.068). These excellent photophysical properties and stabilities of the complexes Kl-4 and the Ru-podate K6 allow their effective use as photosensitizers in electron-transfer processes.Artificial photosynthesis is an important research subject in recent years.* 1 11It is of basic interest since artificial photosynthetic systems mimic the functions of the natural process and are of practical value for solar energy conversion and storage.2 One essential part of such systems is the light-harvesting unit that induces the electron transfer upon excitation. Ru-poly(pyridines),3 metal-porphyrins,4•5 phthalocyanines,6•7 organic dyes,8 and semiconductors9-11 have been used for this purpose.

Highly phosphorescent platinum(ii) emitters: photophysics, materials and biological applications

“…This design principle is reminiscent of the Ru( ii ) polypyridyl complexes supported by “cage” or “hemicage” ligands, which have been shown to display superior emission properties and high photostability against light-induced substitution and decomposition reactions. 28 , 29 , 34 , 35 In the literature, there are few examples of the “one metal ion + one ligand” approach to develop luminescent d 6 Ir( iii ) complexes. 36 This may be due to the formidable challenges in synthesizing chemically inert, rigid hexadentate ligand scaffolds.…”

Mono- and Dinuclear Cationic Iridium(III) Complexes Bearing a 2,5-Dipyridylpyrazine (2,5-dpp) Ligand

“…The ligand 2,5-dipyridylpyrazine (2,5-dpp) has had a long and storied past as a strong π-acceptor σ-donating bis(chelate), particularly involving Ru(II) . Indeed as a result of their properties, the use of 2,5-dpp and other related diazine ligands results in more photostable complexes . Given our interest in the optoelectronic properties of multimetallic cationic iridium(III) complexes, , we targeted complexes 1 and 2 for study, the first examples of iridium(III) complexes incorporating a 2,5-dpp ancillary ligand (Chart ).…”

Molecular Architecture of Polynuclear Ruthenium Bipyridyl Complexes with Controlled Metal Helicity

“…Ruthenium complexes of polypyridyl ligands, in particular 2,2‘-bipyridyl (bpy), have been extensively studied during the last few decades, due to their unique combination of chemical stability, redox properties, reactivity, and luminescence emission from the metastable excited triplet state. , As a consequence, they have been applied to such areas as photocatalysis, molecular recognition (host guest) chemistry, − DNA intercalation, , and artificial photosynthesis/charge separation. − …”