Polypyridines

Tetrathia- and tetraselenafulvalenes, polythiophenes and related compounds, polypyridines as organic electronic conductors 97YGK410. 

Polypyridine ruthenium (II) chelate complex [Ru (Bpy) ] is known to participate in a photoredox reaction on excitation with visible light, coupled with the... 

K. Kalyanasundaram, Photochemistry of Polypyridine and Porphyrin Complexes, Academic Press, London, 1992. 

Dendrimers Containing Polypyridine-Type Metal Complexes. 203... 

Dendrimers built around a metal complex as a core. These compounds can be considered metal complexes of ligands carrying dendritic substituents (Fig. 1 a). The most commonly used metal complex cores are porphyrin complexes, polypyridine complexes, and ferrocene-type compounds. 

The electroactive units in the dendrimers that we are going to discuss are the metal-based moieties. An important requirement for any kind of application is the chemical redox reversibility of such moieties. The most common metal complexes able to exhibit a chemically reversible redox behavior are ferrocene and its derivatives and the iron, ruthenium and osmium complexes of polypyridine ligands. Therefore it is not surprising that most of the investigated dendrimers contain such metal-based moieties. In the electrochemical window accessible in the usual solvents (around +2/-2V) ferrocene-type complexes undergo only one redox process, whereas iron, ruthenium and osmium polypyridine complexes undergo a metal-based oxidation process and at least three ligand-based reduction processes. 

Because of the presence of many polypyridine ligands, each capable of undergoing several reduction processes [38], the electrochemical reduction of this type of dendritic compound produces very complex electron exchange patterns. 

Compound 12 is the largest photoactive dendrimer in which organic branches have been attached around a polypyridine metal core [29]. This dendrimer was obtained by reacting the metal precursor with a modified bpy carrying highly-... 

In the pentaporphyrin array 46, light absorption by the four peripheral Zn-por-phyrins is followed by efficient energy transfer to the central free base porphyrin [68], as it happens in the polypyridine dendrimers discussed above [53b]. 

Denti, G., Campagna, S., Serroni, S., Ciano, N., and Balzani, V. (1992) Decanuclear homo- and hetero-metallic polypyridine complexes Synthesis, absorption spectra, luminescence, electrochemical oxidation, and intercomponent energy transfer./. Am. Chem. Soc. 114, 2944-2950. 

C.H. Brubaker, Michigan State University How did you deposit the polypyridine ligand on the electrode surface ... 

The historical development and elementary operating principles of lasers are briefly summarized. An overview of the characteristics and capabilities of various lasers is provided. Selected applications of lasers to spectroscopic and dynamical problems in chemistry, as well as the role of lasers as effectors of chemical reactivity, are discussed. Studies from these laboratories concerning time-resolved resonance Raman spectroscopy of electronically excited states of metal polypyridine complexes are presented, exemplifying applications of modern laser techniques to problems in inorganic chemistry. 

The photochemical and photophysical properties of Ru(bpy)3 and related d° polypyridine complexes have been the subject of intense recent interest (43-49). This is due to their potential in photochemical energy conversion, their intrinsically significant excited state behavior, and their attractive chemical properties. The structures of the excited states of these complexes are clearly of great interest. 

Laser Studies of Radiationless Decay Mechanisms in Os2+/3+ Polypyridine Complexes... 

P. R. Ashton, R. Ballardini, V. Balzani, E. C. Constable, A. Credi, O. Kocian, S. J. Langford, J. A. Preece, L. Prodi, E. R. Schofield, N. Spencer, J. E Stoddart, S. Wenger, Ru(II)-Polypyridine Complexes Covalently Linked to Electron Acceptors as Wires for Light-Driven Pseudorotaxane-Type Molecular Machines , Chem. Eur. J. 1998, 4, 2411-2422. 

Choudhury and Cole-Hamilton/Tanaka—polypyridine Ru complexes. In... 

Sutin and coworkers—polypyridine Rh complexes. Sutin and coworkers89 tested polypyridine rhodium complexes for water-gas shift and optimized the H2 production rates for what they characterized as a Rh(bpy)2(CO)H2 + catalyst, which predominated when the pH was around 3 or lower. This is formally a Rh(m) complex, and above pH 3, Rh(i) complexes were found and displayed little activity. 

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