Biological iridium complexes

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... 

In this field of luminescent organometallic probes, rhenium and iridium complexes have played so far the major role, thus explaining their predominance in this chapter. The lower number of platinum, rhodium, and gold fluorescent complexes could be explained by demanding synthesis, low luminescence efficiency, poor operational stability, unsuitability for biological applications, or even simply by the lack of systematic studies. 

Iridium complexes have recently been investigated as luminescent sensors able to monitor the variation of homocysteine and cysteine levels in cells (of significance to the physiological balance in biology), in this case using a cationic iridium(III) complex. Furthermore, zinc ion sensing in vitro was possible via a family of cyclometallated iridium(III) polypyridine compounds including a di-2-picolylamine. ... 

Further studies on this system will include IR-SEC experiments under an atmosphere of CO to verify its catalytic activity for CO reduction and to aid in formulating a mechanism for the reaction. Other multimetallic systems used as CO reduction catalysts such as mthenium-, iridium-, and cobalt-based complexes, or metal clusters used as models in the active sites of biological systems, many of which have complex redox behavior can also be investigated using the IR-SEC technique. 

Exploitation of Luminescent Organometallic Rhenium(I) and Iridium(III) Complexes in Biological Studies... 

Iridium(V) complexes, 1158 fluorides, 1158 Iridium(VI) complexes, 1158 Iron complexes acetonitrile, 1210 analysis, 1180, biological systems, 1180 coordination geometries, 1183 coordination numbers, 1182-1187 dinitrosyldicarbonyl, 1188 Mdssbauer spectroscopy, 1181 nitric oxide, 1187-1195 nitrosyls binary, 1188 bis(dithiolene), 1193 carbonyl, 1188 dithiocarbamates, 1192 halides, 1193 iodide, 1193... 

The use of fluorescent organometallic complexes to label biological substrates is beginning to provide some exciting alternatives to the more traditional organic dyes [126], with suitable iridium [127-129], rhodium [130], platinum [131], rhenium [132-135] and osmium [136] examples having recently been reported. The Re diimine wires (13g and 13h, Fig. 13), have been shown to form complexes with the nitric oxide synthase mutant 5114 [137]. Steady-state luminescence measurements with 13h establish a dissociation constant of 100 nM, while 13h binds with a... 

Iridium(lll) complexes, especially those with polypyridine ligands, as therapeutic and bioimaging reagents for cellular applications 12RCA12069. Isolation, biological activity and synthesis of the natural anticancer product eUipticine and related pyridocarbazoles 12RCA8883. 

Dicarba-c/o50-dodecacarborane-containing half—sandwich complexes of ruthenium, osmium, rhodium and iridium Biological relevance and synthetic strategies 12CSR3264. 

Lo KKW, Chung CK, Lee TKM, Lui LFI, Tsang KHK, Zhu N (2003) New luminescent cyclometalated iridium(iii) diimine complexes as biological labeling reagents. Inorg Chem 42(21) 6886-6897... 

More recentiy, Ruiz et al. have developed the synthesis of the ruthenium(II) complex 28 [154]. This makes use of an appropriate combination of previous strategies. The ruthenium atom is stereogenic and this leads to a mixture of dia-stereoisomers, which are eight times more active than cisplatin on T47D breast cancer cell line. This approach can be extended to include complexes of rhodium and iridium [155], and other variants of the method have been used with ruthenium [156]. Alkylidyne and alkylidene derivatives of osmium, exemplified by molecule 29, have been reported [157], but as yet they have not been evaluated biologically. 

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