ISSN:
1434-1948
Keywords:
Amino acids
;
Bioinorganic chemistry
;
Copper
;
Luminescence
;
Ruthenium
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A series of heterobimetallic complexes [{Ru(bipy)2}m-AA{Cu(phen)(H2O)}](PF6)3 (m-AA = Nω-(4-carbonyl-4′-methyl-2,2′-bipyridyl)-L-α,ω-diamino acid; diamino acid (AA): 1b, L-2,3-diaminopropionic acid; 2b, L-2,4-diaminobutyric acid; 3b, L-ornithine, 4b, L-lysine) has been synthesized and characterized starting from the 2,2′-bipyridineruthenium(II)-substituted amino acids [{Ru(bipy)2}m-AA-αN-tBoc]2+ (αN-tBoc-1a-4a, αN-tBoc = Nα-tert-butoxycarbonyl). The metal centers in 1b-4b are bridged by insulating alkyl chains. Consequently, spectroscopic and electrochemical investi-gations confirmed the absence of any appreciable ground-state coupling between ruthenium(II) and copper(II). However, the luminescence of 1b-4b is significantly quenched compared to that of the parent compounds 1a-4a. Quenching was found to proceed only intramolecularly and to be most efficient in 1b with the shortest alkyl spacer. Equilibrium constants for the formation of 1b-4b were determined from luminescence titrations of the respective ruthenium-substituted amino acid with [Cu(phen)(NO3)2]. The complexes 2b-4b (K = 1.61-2.08 × 107M-1) were found to be significantly more stable than 1b (K = 5.7 × 106M -1). This is explained by a stronger electrostatic repulsion between the two metal centers in the latter compound.
Type of Medium:
Electronic Resource
