Ruthenium complex, luminescence properties

Balzani et al. prepared dendrimers with metal complexes serving both as core [36] and as branching unit The metallodendrimer in Fig. 2.10 is constructed solely from polypyridine ligands and transition metal ions. Such dendritic transition metal complexes can be synthesised both convergently and divergently and different transition metal ions (ruthenium/osmium) can be incorporated. This provides a means of influencing the luminescence properties of the den-drimer. Thus the energy transfer process proceeds from the inside outwards in... 

In the future, more correlations should be made, which may eventually allow the design of compounds with predicted luminescent properties. Furthermore, we feel the Ferguson model will be widely accepted and may guide subsequent thinking in the design of efficient luminescent ruthenium(II) complexes. 

Barigelletti F et al (1993) Luminescence properties of rigid rod-like binuclear ruthenium(II)-osmium(II) terpyridine complexes - electronic interaction through phenyl bridges. JCS Chem Commun 942-944... 

A series of ruthenium (II) diimine complexes containing oxa-thiacrown derived from 1,10-phenanthroline have been synthesized and characterized <2007IC720>. The crystal stmctures of [Ru(bpy)2200](PF6)2, [Ru(bpy)2201](ClC>4)2, [Ru(bpy)2202](C104)2 have been determined. The luminescence properties of [Ru(bpy)2200](C104)2 were found to be sensitive and selective toward the presence of Hgz+ ions in an acetonitrile solution. 

A new probe of solvent accessibility of bound sensitizers has been described and tested for the particular case of a series of Ru" and Os photosensitizers bound to sodium lauryl sulphate micelles. The method depends upon the large solvent deuterium effect on excited-state lifetimes, and a correlation has been established between accessibility of bound complexes and hydrophobicity of the ligands. Luminescence properties of amphiphilic annelide-type complexes of ruthenium in micellar phases have been described. In the case of [4,4 -bis(nonadecyl)-2,2 -bipyridyl]bis-[4,4 -di-(10,13,16-trioxaundecyl)-2,2 -bipyridyl]ruthenium dichloride, intramicellar self-quenching effects have an influence on the excited-state lifetime, and the mechanism of self-quenching has been determined. Deactivation of [Ru(bipy)3] by [Co(EDTA)] has been studied in a micellar environment and found to occur by electron transfer at diffusion-controlled rates a stereoselective effect has been observed. ... 

When rare-earth-metal ions such as Eu and Tb are bound to polyelectrolyte membranes such as poly(sodium acrylate) and poly(sodium ethene-sulphonate) their fluorescence intensities are considerably enhanced this is associated with the formation of asymmetric bonds between the rare-earth ions and the acrylate/S03 groups in the polymers. This was confirmed by the addition of EDTA to the Tb -poly(sodium acrylate) complex which, because of its preferential binding to the polymer, displaced Tb ions and resulted in reduced fluorescence of the latter. Stokes shifts of fluorescent dyes in different polymer systems have been related more to mobility effects in the polymer than polarity,and the fluorescence of hydrolysed aspirin has been found to be affected by the nature of different polymer supports.The luminescence properties of cis-(2,2 -bipyridyl)ruthenium(ii) complexes have been found to be influenced by binding the complex to a polymer matrix,as have the luminescence properties of flavones and l-octadecyl-3,3-dimethyl-6 -nitrospiro(indoline-2,2 -2H-benzopyran). Other studies of interest in-... 

Another example of modulation of the electronic interaction between two metal units is schematically represented by compound 41 in Scheme 2(d), for which upon complexation of the vacant 2,2 -bipyridine a perturbation of the luminescence properties of the ruthenium moiety was reported [100]. Methylation caused a quenching of the emission, most likely due to photoinduced electron transfer from the terminal chromophores to the central viologen-type unit. 

There are many examples of polymers containing transition metals coordinated to bipyridine and related ligands (150-164). The luminescent properties of tris(bipyridine)ruthenium(II) complexes have generated a great deal of interest in these materials (152-158). Polymers containing metal ions coordinated to three bipyridine or substituted pyridines can contain the metal as an integral part of the polymer skeleton (66) (165-168), pendent to the polymer backbone (67) (154 156), or in a group pendent to the polymer backbone (68) (157,158). 

The attachment of a redox center to a calkarene-substituted PPy has been achieved by the anodic oxidation of pyrrole-substituted trisbipyridylruthenium(II)-Iinked calixarenes [307]. However, only thin films with a low amount of immobilized [Ru(bpy)3] (bpy = 2,2 -bipyridine) were obtained by homopolymerization. Thicker films could be grown from copolymerization with iV-methylpyrrole. Even if the sensory properties of these polymers have not been investigated yet, it can be predicted that the electrochemical and/or luminescent responses of the ruthenium complex could be changed upon the complexation of a guest cation by the immobilized host calixarene. It must be pointed out that such a recognition event had been already observed with a polypyrrole film N-substituted by an aza crown ether-linked bipyridine ruthenimn (II) complex [271]. 

Scheme 16 shows the second strategy utilized to prepare this class of polymer. In this example, a ruthenium-containing monomer (71) was reacted with 65 and 70 to produce polymer 72. Polymers prepared using the derivatized styrene monomers were much more soluble than polymers prepared by the grafting approach. The absorption and luminescent properties of polymers 69 and 72 were greater than those of their corresponding monomeric metallated analc es due to efficient energy transfer between the dyes and the complexes. ... 

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