Photoinduced energy transfer between Re(I) and Ru(II) termini connected through a new exo-ditopic bis-phenanthroline ligand fused to a central macrocycle spacer: Synthesis, structure, and electrochemical and photophysical properties of a heterodinuclear complex

 
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Photoinduced energy transfer between Re(I) and Ru(II) termini connected through a new exo-ditopic bis-phenanthroline ligand fused to a central macrocycle spacer: Synthesis, structure, and electrochemical and photophysical properties of a heterodinuclear complex (EN)

Lazarides, T. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Lazarides, T. (EN)

A new ligand L-1 has been prepared in which two 1,10-phenanthroline fragments are separated by an 18-crown-6 macrocyclic spacer. This was used to prepare the heterodinuclear complex [(bipy)(2)Ru(mu-L-1)Re(CO)(3)Cl][PF6](2) [Ru(L-1)Re] in which the {Ru(bipy)(2)(phen)}(2+) and {Re(CO)Cl(phen)} chromophores are separated by a saturated and fairly flexible crown-ether fragment. On the basis of photophysical studies on Ru(L-1)Re and associated mononuclear Ru(II) and Re(I) complexes, Re -> Ru photoinduced energy-transfer occurs with a rate constant of 1.9 x 10(8) s(-1) in solution room temperature leading to near-complete quenching of the Re(I)-based luminescence. At 77 K the Re(I)-based luminescence component is completely quenched. Calculations on the efficiency of both Forster and Dexter energy-transfer as a function of (ReRu)-Ru-... distance in this system suggest that a folded conformation of the complex, in which the (ReRu)-Ru-... separation is much shorter than that implied by the extended conformation detected crystallographically, is responsible for the energy-transfer, since neither Forster nor Dexter Re -> Ru energy-transfer should be possible with the complex in an extended conformation. Addition of K+ or Ba2+ salts to solutions of Ru(L-1)Re had no effect on the photophysical properties, probably because the association constants are too low to give significant metal-ion binding in the macrocycle at the low concentrations employed. (c) 2006 Elsevier B.V. All rights reserved. (EN)

ruthenium (EN)


Inorganica Chimica Acta (EN)

English

2007


Elsevier (EN)



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