Ruthenium phthalocyanine

Almost every metal atom can be inserted into the center of the phthalocyanine ring. Although the chemistry of the central metal atom is sometimes influenced in an extended way by the phthalocyanine macrocycle (for example the preferred oxidation state of ruthenium is changed from + III to + II going from metal-free to ruthenium phthalocyanine) it is obvious that the chemistry of the coordinated metal of metal phthalocyanines cannot be generalized. The reactions of the central metal atom depend very much on the properties of the metal. 

Water-soluble ruthenium phthalocyanines show promise as photodynamic cancer therapy agents [129b],... 

The ruthenium phthalocyanine complex (54) shows a visible absorption band at 650 nm (6-49,000 cm" ) and a phosphorescence band located at 895 nm. 

Li et al. [47] fabricated SAMs of ruthenium phthalocyanine (RuPc) on a silver substrate precoated with an SAM of 4-mercaptopyridine (PySH) or l,4-bis[2-(4-pyridyl)ethenyl]-benzene (BPENB). SERS spectroscopy was used to explore the structure and orientation of the self-assembled films, and they successfully observed Raman bands due to vibrational modes of the pigment molecules in the composite films in the SERS spectra. 

Zeolite-encapsulated perfluorinated ruthenium phthalocyanines catalyze the oxidation of cyclohexane with t-BuOOH [146]. A dioxoruthenium complex with a D4-chiral porphyrin ligand has been used for the enantioselective hydroxylation of ethylbenzene to give a-phenylethyl alcohol with 72% e.e. [147]. 

Figure 14. (a) Structure of a zeolite-entrapped perfluorinated ruthenium phthalocyanine (RuFi6Pc) complex used in epoxidation reactions, (b) Comparison of turnover numbers for cyclohexane oxidation using ruthenium phthalocyanine (RuPc), RuFi Pc and zeolite X-entrapped RuFi Pc. 

The use of metal phthalocyanine compounds has also been described (66,67). The catalysts can either be supported on an inert carrier or used in a liquid-liquid two-phase system. Various functionalized phthalocyanine ruthenium complexes have been mentioned for the reaction of interest. For instance, ruthenium phthalocyanine disulfonate transformed hept-3-ene into 3- -propylpentanol (80°C, 18 hours, 120 bar) in a two-phase system. Further details (67) on the preparation of metal complexes supported on silica- and alumina-type supports have appeared. Generally, a mixture of metal phthalocyanine sulfonate and hydrated alumina pro-... 

Synthesis, properties, and applications of ruthenium phthalocyanine and naphthalocyanine complexes 07CCR1128. 

Ruthenium phthalocyanine 49 (R = -H, M = Ru(II)) monolayers were obtained by self-assembly on pyridyl-functionalized SiOa or AI2O3 substrates by coordination between Ru and the pyridino group to obtain 63 [155]. The pyridino-functionalized metal oxides were dipped into a solution containing the more soluble benzonitrile derivative of the phthalocyanine RuPc(NC-C6H5)2, and ligand exchange reactions led to 63. Strategies have been described to immobilize a second layer of a Ru-phthalocyanine or a Co tetraphenyl-porphyrin. 

Phthalocyanine complexes within zeolites have also been prepared by the ship-in-a-bottle method (see Section 6.6), and have subsequently been investigated as selective oxidation catalysts, where their planar metal-N4 centres mimic the active sites of enzymes such as cytochrome P450, which is able to oxidize alkanes with molecular oxygen. Cobalt, iron and ruthenium phthalocyanines encapsulated within faujasitic zeolites are active for the oxidation of alkanes with oxygen sources such as iodosobenzene and hydroperoxides. Following a similar route, Balkus prepared Ru(II)-perchloro- and perfluorophthalocyanines inside zeolite X and used these composites for the selective catalytic oxidation of alkanes (tert-butylhydroperoxide). The introduction of fluorinated in place of non-fluorinated ligands increases the resistance of the complex to deactivation. 

Ebadi, M. and A.B.R Lever (2003). Electroreduction of nitrite catalyzed by a dinu-clear ruthenium phthalocyanine modified graphite electrode. J. Porphyrins Phthalo-cyanines, 7, 529-539. 

Ebadi, M. (2003). Electrocatalytic oxidation and flow amperometric detection of hydrazine on a dinuclear ruthenium phthalocyanine-modified electrode. Can. J. Chem. 81(2), 161-168. 

Nazeeruddin, M.K., R. Humphry-Baker, M. Gratzel, and B.A. Murrer (1998). Efficient near IR sensitization of nanocrystalline Ti02 films by ruthenium phthalocyanines. Chem. Commun. 719-720. 

Hue, V, J.R Bourgoin, C. Bureau, F. Valin, G. Zalczer, and S. Palacin (1999). Self-assembled mono- and multilayers on gold from 1,4-diisocyanobenzene and ruthenium phthalocyanine. J. Phys. Chem. B 103, 10489. 

Surface modification reactions are important not only for engineering of surface energy and interfacial properties such as wetting, adhesion, and friction, but also for providing active surfaces for the attachment of molecules with different properties such as polymers [552], ruthenium phthalocyanine (RuPc) [560], jr-electron moieties [561], and deoxyribonucleic acid (DNA) [566, 570]. Organosilanes with more than one reactive group have the potential of binding to more than one surface... 

The synthesis and properties of ruthenium phthalocyanines, RuPcs, have been well studied over the last 30 years, but only recently they have been rediscovered for their potential application in metallosupramolecular chemistry. Basically, RuPcs are different from ZnPcs in their tendency to form stronger complexes with basic sp nitrogen atoms (pyridine and imidazole) and in the possibility to form complexes on one side or on both sides of the macrocycle. Another interesting point of ruthenium phthalocyanines resides in the longer lifetime of their radical-ion-pair state when compared to that of zinc phthalocyanines. Thus, all things being equal, RuPcs display a richer potential for supramolecular chemistry than ZnPcs. 

The synthesis of ruthenium-metallated Pc derivatives using Ru3(CO)i2 in benzonitrile afforded ruthenium phthalocyanines either monocoordinated with CO or dicoordinated with benzonitrile. Cook and colleagues were the first to predict their utility in the preparation of further (pyridyl) ligated derivatives and showed that it was indeed straightforward. This chemistry is sufficiently robust and efficient to permit elaborate supramolecular complexes to be prepared, as demonstrated by the synthesis of porphyrin-phthalocyanine multichromophores 21 and 22, as illustrated in Figure 15. The absorption spectra of these arrays are essentially the sums of spectra of the starting materials. These observations indicate that there is little ground-state electronic interaction between the perpendicular maaocycles, in accordance with previous results published by Ng and Li (Section 4.1.1). ... 

Figure 15 Supramolecular triads 21 and 22 formed between a ruthenium carbonyl phthalocyanine and meso-bis-4-pyridyl porphyrin (21), and ruthenium phthalocyanine and meso-A-pynAy porphyrin (22).

Figure 18 Ruthenium phthalocyanine 28 and oligothiophene-functionaUzed pyridines 25-27.

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