Ruthenium complexes photochemistry

In the most congested case, (Ru(terpy )(dmp)(CH3SCH3)2+), the photosubstitution quantum yield was shown to be

room temperature in pyridine, which is an extremely high value in ruthenium(II) photochemistry. The control of the bulkiness of the spectator chelates, leading to the control of the congestion of the complex and, hence, to the efficiency of ligand photoexpulsion, is a specific feature of the Ru(terpy)(phen)(L)2+ core. This... 

Photochemical methods offer a convenient tool to study intra- and interprotein ET because of their time resolution and selectivity. Various mechanistic and design approaches based on photochemistry of metal complexes have been undertaken. Most of the studies on protein electron transfer processes have been done for hae-moproteins using among others ruthenium complex as a photosensitizer, modified haemoproteins in which haem iron is substituted by another metal (mainly Zn), and CO-bonded haem proteins [6,7],... 

Smface modification with ruthenium complexes has proven valuable in studies of both interprotein and intraprotein electron transfer in systems that are difflcult to stndy by traditional kinetic tools. The choice of ruthenium complexes in these investigations stems from an extensive photochemistry as well as exceptional thermal stability. The photochemistry provides a means of examining reactions over a time range of nanoseconds to seconds by laser-flash photolysis and the thermal stability allows researchers to covalently bind a wide variety of complexes to proteins with... 

Special interest was focused on the photochemistry and redox properties of mononuclear ruthenium complexes.20 Examples show the nucleophilic attack of one of the N atoms of 1,8-naphthyridine on the coordinated CO in [Ru(bipy)2(napy)(CO)]2+ upon le reduction of the napy moiety (Scheme 2). Such a type of metallacyclization enables the reduction of the CO group, derived from the electrochemical reduction of C02 catalyzed by [Ru(bipy)(napy)2(CO)2](PF6)2, to produce acetone in the presence of Me4NBF4.21,22 An unusual result is the simultaneous formation of a carbene ligand and the addition of the methoxo group to the naphthyridine ring upon reaction of [Ru(bipy)2(napy)]2+ with propiolic acid in methanol (Scheme 2).23... 

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. 

Polypyridyl ruthenium complexes are known for their interesting photophysical and redox properties as well as their countless appHcations. Polypyridine ruthenium compounds display weU-defined chemistry, photochemistry, and photophysical properties they have found use as artificial light-harvesting systems for technological purposes and as... 

Kalyanasundaram K., Gratzel M. Applications of functionalized transition metal con5)lexes in photonic and optoelectronic devices. Coord. Chem. Rev. 1998 77 347-414 Kamat P.V. Photoelectrochemistry in particulate systems. 3. Phototransformations in the colloidal TiOa-thiocyanate system. Langmuir 1985 1 608-611 Kamat P.V., Bedja I., Hotchandani S., Patterson L.K. Photosensitization of nanocrystalline semiconductor films. Modulation of electron transfer between excited ruthenium complex and SnOa nanocrystalUne with an externally applied bias. J. Phys. Chem. 1996 100 4900-4908 Kamat P.V., Vinodgopal K. Environmental photochemistry with semiconductor nanoparticles. Mol. Supramol. Photochem. 1998 2 307-350... 

Kinetics of aquation of [Ru(LLLL)X2], with LLLL = cyclam, 2,3,2-tet, en2, or (NH3)4, and X = Cl or Br, have been followed by cyclic voltammetry. Rate constants, and activation parameters (A// and A5 ) have been evaluated, and compared with kinetic parameters for reactions of analogous compounds of ruthenium(III) and cobalt(III). Similar trends obtain for all three sets of complexes. There is retention of stereochemistry, rates decrease as the extent of chelation in LLLL increases, and trans complexes are less labile than cis analogs. Reactivities are determined by solvation of the initial and transition states, by nephelauxetic effects, and by a-trans effects. A limiting dissociative (D) mechanism is proposed for the ruthenium complexes, with square-pyramidal geometry for the transient intermediate [cf. rhodium(III) photochemistry below. Section 5.8.10]. Differences in isomer lability have also been described for... 

The 3,3, 5,5 -tetrapyridylbiphenyl (tterpy) ligand is one which allows for the synthesis of bimetallic ruthenium complexes. Such complexes could lead to the development of some interesting photochemistry because of their exceptionally strong electronic interactions between redox centers. ... 

The photochemical studies of transition metal hydride complexes that have appeared in the chemical literature are reviewed, with primary emphasis on studies of iridium and ruthenium that were conducted by our research group. The photochemistry of the molybdenum hydride complexes Mo(tj5-C5H5)2M2] and [MoH4(dppe)2] (dppe = Ph2PCH2CH2PPh2), which eliminate H2 upon photolysis, is discussed in detail. The photoinduced elimination of molecular hydrogen from di-and polyhydride complexes of the transition elements is proposed to be a general reaction pathway. 

Mo(r75-C5H5)2H2] and [MoH dppe ]. Our studies of the di- and trihydride complexes of ruthenium and iridium, described above and published previously (27,35), and those of other workers (discussed at the beginning of this chapter), indicate that photoinduced elimination of molecular hydrogen is a common reaction pathway for di- and polyhydride complexes. To demonstrate the photoreaction s generality and its utility for generating otherwise unattainable, extremely reactive metal complexes, we have begun to study the photochemistry of polyhydride complexes of the early transition metals. We focused initially... 

Most photosensitizers, however, are reasonably photostable compounds, and their optical properties have been studied in depth. In particular, there has been much interest in ruthenium-based photosensitizers such as [Ru(bpy)3]2+ and [Ru(phen)3]2+, due to their stability and absorption of visible light. Detailed information on their optical properties, including ground and excited state information in relation to photosensitization, has been reviewed by Creutz et al. [16]. Similarly, the photochemistry and photophysics of rhenium complexes, as discussed here, have been reviewed in detail by Kirgan et al. [7]. 

Szacilowski K, Macyk W, Stochel G, Stasicka Z, Sostero S, Traverso O. Ligand and medium controlled photochemistry of iron and ruthenium mixed-ligand complexes prospecting for versatile systems. Coord Chem Rev 2000 208 277-97. 

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