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Catechol‐Bearing Dipyrazinylpyridine Complexes of Ruthenium(II)
Author(s) -
Almutlaq Fahad A.,
Potvin Pierre G.,
Philippopoulos Athanassios I.,
Falaras Polycarpos
Publication year - 2007
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200600772
Subject(s) - chemistry , ruthenium , catechol , ligand (biochemistry) , pyridine , yield (engineering) , hydrolysis , medicinal chemistry , methylene , stereochemistry , catalysis , organic chemistry , biochemistry , materials science , receptor , metallurgy
Abstract The new tridentate ligand 4‐(3,4‐methylenedioxyphenyl)‐2,6‐dipyrazinylpyridine ( 2 ) was prepared in good yield in a one‐pot reaction. The Ru II complexes [Ru( 2 ) 2 ](PF 6 ) 2 and [Ru( 1 )( 2 )](PF 6 ) 2 [ 1 is 2,6‐dipyrazinyl‐4‐(4‐tolyl)pyridine] were prepared in good yields and tested as photosensitizers against [Ru( 1 ) 2 ](PF 6 ) 2 and [Ru(ttpy) 2 ](PF 6 ) 2 [ttpy is 4′‐(4‐tolyl)‐2,2′:6′,2″‐terpyridine]. The photosensitization ability follows the order [Ru( 1 ) 2 ](PF 6 ) 2 > [Ru( 1 )( 2 )](PF 6 ) 2 > [Ru( 2 ) 2 ](PF 6 ) 2 >> [Ru(ttpy) 2 ](PF 6 ) 2 , which is explainable in terms of mechanism and driving force. Hydrolysis of the methylene acetal function affords the catechol‐appended complexes [Ru( 3 ) 2 ](PF 6 ) 2 and [Ru( 1 )( 3 )](PF 6 ) 2 [ 3 is 4‐(3,4‐dihydroxyphenyl)‐2,6‐dipyrazinylpyridine] in excellent yields. These insoluble, paramagnetic precipitates when tested as photosensitizers in homogeneous solution and in one case adsorbed on titania are able to generate photocurrents in a photovoltaic cell, albeit more weakly compared to the so‐called N719 dye. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)