The binding of [Ru(bpy) 3 ] 2+ (bpy = 2,2'bipyridine) [Ru(dmbpy) 3 ] 2+ (dmbpy = 4,4'dimethyl-2, 2'bipyridine) complexes with quinones (1,4benzoquinone (BQ), 2methyl-1,4-benzoquinone (MBQ), 2,6-dimethyl-1,4-benzoquinone (DMBQ)) have been studied in N, Ndimethyl formamide by means of absorption spectral techniques. The complexes have absorption maximum in the range 453 nm to 458 nm. The emission maximum is in the range 603-610 nm. The binding constant (k b) for these reactions are determined from the Benesi Hildebrand equation using the absorption intensity data. The observed binding constant values are sensitive to the nature of the ligand, as well as the quenchers. Structural effect seems a play an important role on the binding of these quinones with these complexes.
Two Ruthenium(II)) polypyridyl complexes [Ru(NN) 3 ] 2+ [(NN)→bpy , dmbpy] were synthesised. The binding interaction of these ruthenium complexes with para quinones have been studied by absorption spectral technique. These metal complexes have the absorption maximum in the range of 448 -458 nm. They have the emission maximum in the range 590-610 nm. The binding constant (k b ) for these complexes are determined from the Benesi-Hildebrand equation using the absorption intensity data. Structural effect plays an important role in the binding of the quinones with the complexes.
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Introduction:-Quinones are ubiquitous in nature. p-quinones are important molecules in biological electron transport. They act as electron acceptor in photosynthesis [1][2][3]. They are well known for their citotoxicity. They have very high toxicological and pharmacological effects. They are used as anticancer drugs. They have antiviral, antifungal properties. Quinones have the capacity to accept electrons and are easy to protonate. They form stable hydrogen bonds. Due to their high mobility and small size, they have the property to get reduced. In order to understand the electron transfer properties of quinones, several photosensitizers have been designed. Inter and intra molecular electro transfer reactions have been studied.Their properties can be changed on complexation with proteins [4]. Transition metal complexes have received a considerable amount of attention over the past three decades [5][6][7]. Of these, particularly ruthenium (II) polypyridyl complexes have received much attention due to its tunable photophysical and photochemical properties. These complexes have a potential application in the field of photochemistry and biochemistry [8][9][10]. Recently reports show the advantages of ruthenium complexes in the field of cellular imaging and act as anticancer agents [11][12][13][14]. They act as good photocatalysts, particularly in the splitting of water molecule into O 2 and H 2 , used in dye sensitized solar cells and used in photodynamic therapy. We present here a comprehensive study of interaction of ruthenium polypyridyl complexes with quinones in aqueous medium by using UV/Vis spectrophotometric parameters. , where NN = 2,2-bipyridine (bpy) and 4,4'-dimethyl-2,2 ' -bibyridine (dmbpy) were prepared by reacting RuCl 3 .3H 2 O with the corresponding ligands according to the known procedures [15,16]. The ligands and quinones used for this present work were procured from Sigma Aldrich. Binding studies were carried out using double distilled water.All experiments were carried out at room temperature.
Photoinduced electron transfer reaction between the excited state ruthenium (II) polypyridyl complexes and quinones has been investigated in cetyltrimethylammonium bromide using luminescent quenching techniques. The complexes have the absorption and emission maximum in the range 452-468 nm and 594-617 nm respectively. The static nature of quenching is confirmed from the ground state absorption studies. The association constants for the complexes with quinones are calculated from the Benesi-Hildebrand plots using absorption spectral data. The value of quenching rate constant (k q) is highly sensitive to the nature of the ligand and the quencher, the medium, structure and size of the quenchers. Compared to the aqueous medium, the electron transfer rate is altered in CTAB medium. The oxidative nature of the quenching is confirmed by the formation of Ru 3+ ion and quinone anion radical.
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