Azobenzene based Zn(II)/Ru(II) coordination-organometallic hybrid complexes: Influence of π-conjugation, donor/acceptor substituent's and coligands on electrochemical, luminescence and NLO properties

Abstract

A new series of azobenzene based heterobinuclear coordination-organometallic hybrid complexes of the type [Zn(phen)(RC6H4HCN(O)C6H3NNC6H4CCRu(dppe)2Cl)]X (1a-6a) and [Zn(bipy)(RC6H4HCN(O)C6H3NNC6H4CCRu(dppe)2Cl)]X (1b-6b) have been prepared and characterized (where R= CCC6H4OCH3, CCC6H4NO2; XClO4, BF4, PF6; phen= 1,10-phenanth-roline, bipy= 2,2′-bipyridine). TGA was carried out to study the thermal behaviour of the complexes. X-ray powder diffraction and SEM studies of the representative complexes 2a and 5b are used to clarify the crystal structure and morphology of the complexes. Cyclic voltammetry study indicate a quasireversible redox behaviour corresponding to Ru(II)/Ru(III) couple susceptible to variation of electron donating/accepting properties of substituent group in the complexes. Room temperature luminescence is observed for all complexes corresponding to π→π*ILCT transition indicating that the emission wavelength is finely tuned by increasing π-conjugation and variation of substituent groups with different electronic effects in the complexes. The second harmonic generation (SHG) efficiency of the complexes was measured by Kurtz-powder technique indicating that all complexes display the second harmonic generation (SHG) property.