Onset of Luminescence in Novel Chromophore-Quencher Rhenium(I) Complexes ",

CATTANEO, MAURICIO.; FAGALDE, FLORENCIA; KATZ, NÉSTOR E.; MORAN, EDUARDO; BORSARELLI, CLAUDIO

Cape Town, Sudafrica

Congreso; XXXVII International Conference on Coordination Chemistry; 2006

IUPAC

Novel chromophore-quencher rhenium(I) tricarbonyl complexes, of formulae [Re(Ph2bpy)(CO)3(PCA)]+ (1), [(Ph2bpy)(CO)3Re(PCA)Re(CO)3(Ph2bpy)]2+ (2), and [(Ph2bpy)(CO)3ReI(PCA)RuII(NH3)5]3+ (3) ( Ph2bpy = 4,4´-diphenyl-2,2?-bipyridine, PCA = 4-pyridinecarboxaldheyde azine), have been synthesized as PF6- salts and characterized by spectroscopic, electrochemical and photophysical techniques. Complexes 1 and 2 emit at lem = 553 nm (lex = 350 nm) in CH3CN at room temperature with quantum yields f = 0.0010 and f = 0.0045 respectively. The lifetime of the excited state of complex 2 (shown below) is t = 865 ns, as determined by laser flash photolysis at lex = 355 nm. The onset of luminescence of the complexes described in this work, in contrast to those described before,1  can be attributed to the lowering in energy of the emitting state caused by introducing the electron-withdrawing phenyl substituents in the bpy ring. Spectroelectrochemistry of complex 3 in CH3CN  discloses a redox-induced PCA isomerization process that gives rise to a new heterodinuclear  complex, [(Ph2bpy)(CO)3ReI(PCA)RuIII(NH3)5]4+ (4), with a ReI ®  RuIII   MMCT band at lmax = 497 nm. 1.   M. Cattaneo, F. Fagalde, N. E. Katz, A. M. Leiva and R. Schmehl, Inorg. Chem. 45, 127 (2006).