Iridium complexes, luminescence

Iridium(III) complexes have been widely explored in the past few decades because of their outstanding photophysical properties and superior photo- and chemical stability (123-129). Much effort has been devoted to both neutral and cationic luminescent iridium complexes in which fine-timing of the energy of their long-lived excited state can be achieved by proper choice of the coordinated ligands (130-136). 

Fig. 31 Luminescent iridium complex-based sensor for homocysteine...

A luminescent unit was prepared by the Shinozaki et al. (1) by mixing iridium complexes, (I) and (II), with bisphenol A diglycidyl ether and 5-methylhexa-hydrophthalic anhydride. Additional luminescent derivatives, (III) and (IV), were prepared by Igarashi (2). 

Reactions of the dichloro-bridged rhodium(ni) and iridium(III) dimers with diimine ligands resulted iu the formation of the luminescent mononuclear complexes [M(N C)2(N N)]+ (M = Ir, Rh = ppy, bzq N N = bpy, phen). The electronic absorption and emission spectra of these complexes are shown in Figure 8. The rhodium(III) complexes displayed very long-lived emission in... 

In another example, the cyclometalated iridium complex [Ir(ppy)2(4-vinylpyridine)Cl] has been attached via hydrosilation see Hydrosilation) to hydride-terminated poly(dimethylsiloxane) to produce a luminescent material. Evaluation of this material as a luminescent oxygen sensor revealed significantly improved sensitivity over dispersions of the original vinyl pyridine complex in poly(dimethylsiloxane). The luminescent material was blended with polystyrene to give a new sensor that exhibited increased sensitivity and maintained short response times to rapid changes in air pressure. 

P-Cyclodextrines, appended to a ruthenium complex, have been employed as hosts for iridium and osmium complexes bearing adamantyl or biphenyl moieties, which form strong host-guest complexes with P-cyclodextrines (see Fig. 3). In such systems, photoinduced energy transfer can occur from the periphery, upon complexation of the iridium units, toward the central ruthenium acceptor, or switched in the other direction, from the ruthenium to the periphery when the osmium moieties are assembled (see Fig. 3) 42). The lowest excited state is in fact localized on the osmium center, while the highest luminescent excited state belongs to the iridium complex (see Fig. 3 right). 

Rothe C, King S, Monkman A (2006) Long-range resonantly enhanced triplet formation in luminescent polymers doped with iridium complexes. Nat Mater 5(6) 463—466... 

Ruthenium complexes used to lead research in photochemistry of metal compounds, but rhodium complexes have recently overtaken them as the key target compounds due to their applications in OLEDs. This is a lively and ever-changing field for example, over 90% of luminescent iridum(III) complexes have been reported only in the six years to the beginning of 2009. With their luminescence tuneable through ligand choice, iridium complexes are firm candidates for optical display applications. 

Polystyrenes have also been used to support chromophores useful in organic light-emitting diodes (OLEDs). Week and coworkers have attached tris(2-phenylpyridine) iridium complexes to aminomethylated polystyrene using a Schiff base reaction, 4 [21]. There was no major diminution of the desirable luminescence properties of the iridium complexes (high emission quantum yields of 0.23 and lifetimes of about a microsecond). Similar results have been reported for aluminum and boron 8-hydroxy quinoline complexes tethered to polystyrene using Schiff base condensation [22]. 

Luminescent iridium(III) polyimine complexes with heterocycles as ligands 00CSR385. 

The luminescent iridium (111) complexes [Ir(pba)2 (N-N)] (PFe) displayed indistinguishable and structured emission spectra with very long emission lifetimes (4.3-5.7 J,s) in fluid solutions at 298 These observations suggested that the emissive state of these complexes was IL n (pba))... 

Balch, A.L. Catalano. V.J. Ligation-induced changes in metal-metal bonding in luminescent binuclear complexes containing gold(I) and iridium(I). Inorg. Chem. 1991, 30, 1302. 

Abstract Considerable studies have been made on iridium complexes during the past 10 years, due to their high quantum efficiency, color tenability, and potential applications in various areas. In this chapter, we review the synthesis, structure, and photophysical properties of luminescent Ir complexes, as well as their applications in organic light-emitting diodes (OLEDs), biological labeling, sensitizers of luminescence, and chemosensors. 

Keywords Biological labeling, Chemosensor, Iridium complex, Luminescent, Organic light-emitting diodes. Structure, Synthesis... 

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