Spectroscopic and electrochemical investigation of coordination complexes of octakis(benzylthio)tetraazaporphyrincobalt(II)

摘要

Synthesis of new bichromophoric di- and pentanuclear complexes 2-7 by datively binding (bpy)(2)Ru-II, (phen)(2)Ru-II and Cp (PPh3)Ru-II units to the periphery of [Co(OBTTAP)], 1, and their spectroscopic properties are described. IR, H-1 NMR, UV-Vis, and mass spectral data were used for their characterization. Relative intensities and positions of the Soret and Q-bands absorptions in the di- and pentanuclear complexes were observed shifted vis-a-vis that in the precursor complex [Co(OBTTAP)], 1. These complexes particularly, those possessing [Co(OBTTAP)] and (bpy)(2)Ru-II/(phen)(2)Ru-II units, exhibited efficient inter-component electronic excitation energy transfer in their fluorescence excitation-emission spectra, that are suggestive of a high degree of inter-component electronic interaction in them. Also, the electrode activity of the complexes improved upon binding of the peripheral units and they exhibited multiple one-electron reversible oxidation waves in the cyclic voltammograrns. These effects have been explained in terms of d pi(S)-d pi(Ru) interactions. (c) 2005 Elsevier B.V. All rights reserved.