Synthesis, spectroscopic and electrochemical investigations of supramolecular nickel(II)tetraazaporphyrin complexes

Abstract

The ( bpy )2RuIIand ( phen )2RuIImoieties were linked to [ Ni ( OBTTAP )]1, periphery through coordinate bonds in order to synthesize cationic di- and pentanuclear complexes 2-5 that were obtained as PF6−salts. They were characterized by IR,1H NMR, UV-vis, and mass spectral data. The electronic absorption, emission and redox data of these bichromophoric systems indicate the presence of a high degree of intercomponent electronic interaction. The position and relative intensities of the Soret and Q bands in these complexes is altered due to peripheral binding of the metal units. The compounds were non-emissive for the Q band excitation but, Soret excitation led to a strong S2emission, observed between 400-450 nm. In cyclic voltammetry, the compounds exhibited one Ru centered oxidation together with one or two OBTTAP centered oxidations. The RuII/ RuIIIoxidations were observed at significantly lower potentials as compared to the corresponding simple maleonitrile-benzylthioether complexes and has been interpretted in terms of weaker d π( S )– d π( Ru ) interactions.