Amphiphilic ruthenium complex

Yamada, S., Kawazu. M., Matsuo, T. Second-order nonlinear optical effects in stacked assemblies of ultrathin polymer films with amphiphilic ruthenium complex. J. Phys. Chem. 98, 3573-3574 (1994)... 

A structurally related amphiphilic ruthenium complex of bis(bipyridine) dipyridylmethylene distearyl ester (317) was prepared and isolated as its hexafluorophosphate or perchlorate salt. In particular, the PFg salt shows a lamellar mesophase in water which, however, quickly rearranges into the more stable multilayer vesicles. ... 

Fig. 3.1 Transmission electron micrograh (TEM) and model of a multilayered micelle made of the depicted amphiphilic ruthenium complex with PF6 -counterions. The whole bilayer assembly does not measureably dissociate in aqueous solution and can be isolated in the dry state. It is therefore a noncovalent polymer. ...

Two celebrated early investigations of transmembrane oxidation-reduction were interpreted in terms of direct electron exchange between redox partners bound at the opposite vesicle interfaces. One involved apparent reduction of diheptylviologen [( 7)2 V +] in the inner aqueous phase of phosphatidylcholine liposomes by EDTA in the bulk phase that was mediated by membrane-bound amphiphilic Ru(bpy)3 + analogs the ruthenium complexes acted as photosensitizers and were presumed to function as electron relays by undergoing Ru(II)-Ru(III) electron exchange across the bilayer [105]. The other apparently involved direct electron transfer between photoexcited Ru(bpy)3 + and bound at the opposite interfaces of asym-... 

Yamada, S.. Yamada. Y., Nakano, T., Matsuo, T. In-situ observation of second harmonic hght from amphiphilic ruthenium(II) tris(2, 2 -bipyridine) complex at glass/liquid interface. Chem. Lett. 937-940 (1994)... 

Ruthenium complexes generated from the amphiphilic phosphines 24 (see also Section 7.5) were used for the selective hydrogenation of 3-methyl-2-butenal (pre-nal) to 3-methyl-2-butenol (prenol) in isopropanol/water mixtures [49]. High conversions of up to 100% and selectivities of 90-96% were achieved with ligands of the type 24 containing long poly ether chains [49]. 

The low efficiencies could be due to lack of intimate contact (interface) between the sensitizer (which is hydrophilic) and the spirobifluorene (which is hydrophobic). Moreover, the surface charge also plays a significant role in the regeneration of the dye by the electrolyte.98 In an effort to reduce the charge of the sensitizer and improve the interfacial properties between the surface-bound sensitizer and the spirobifluorene hole-carrier, amphiphilic heteroleptic ruthenium(II) complexes ((48)-(53)) have been used as sensitizers. These complexes show excellent stability and good interfacial properties with hole-transport materials, resulting in improved efficiencies for the solar cells. 

Amphiphilic resin supported ruthenium(II) complexes similar to those displayed in structure 1 were employed as recyclable catalysts for dimethylformamide production from supercritical C02 itself [96]. Tertiary phosphines were attached to crosslinked polystyrene-poly(ethyleneglycol) graft copolymers (PS-PEG resin) with amino groups to form an immobilized chelating phosphine. In this case recycling was not particularly effective as catalytic activity declined with each subsequent cycle, probably due to oxidation of the phosphines and metal leaching. 

In a very recent set of papers [48,54,59,60,131,132,324-328], the synthesis and characterization of metallosupramolecular amphiphilic block copolymers containing a hydrophilic PEO block linked to a hydrophobic PS or PEB block through a fozs-2,2/ 6/,2/terpyridine-ruthenium(II) complex have been described. These copolymers form the so-called metallosupramolecular micelles . 

Upon combination of complexes 1 and 2 in an equimolar 0.025 mM aqueous solution, the absorption spectrum displayed features of both complexes. On the contrary, the emission spectrum of such mixture showed a maximum centered at 645 nm, which resembled only one of the complex 1, while the emission of complex 2 was not detected. The time-resolved emission analysis confirmed that the decay was only related to complex 1 above the CMC. These findings strongly indicate a full and efficient energy transfer process involving the iridium-based metallosurfactant 2, being quenched by the ruthenium-based amphiphilic complex 1 in a system that can be depicted as a mixed aggregate. 

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. ... 

During ATRP, alkyl halides function as initiators while transition metal complexes (ruthenium, osmium, iron, copper and so on) act as the catalyst. Metal complexes are used to generate radicals (such as peroxide) via a one electron transfer process and during this process the transition metal becomes oxidised. Thus, ATRP is a reversible-deactivation radical polymerisation and can be employed to prepare polymers with similar molecular weight (MW) and low MW distribution. Advantages of ATRP are the ease of preparation, use of commercially available and inexpensive catalysts and initiators [14, 15]. The synthesis and process development of ATRP, as well as some new hybrid materials made of amphiphilic polymers, have been reported in the literature (Figure 2.3) [16, 17]. 

Ruthenium tris-2,2 -bipyridine complexes are known to play an active role as photochemical redox agents in the solar energy conversion The corresponding amphiphilic complex 96 does not polymerize, presumably due to sterical reasons. The Ru ions are octahedrally coordinated by the three 2,2 -bipyridine ligands, which causes a very bulky size of the head group. As a consequence, the distances between adjacent diyne units likely become too large for a solid-state 1,4-addition... 

---