Organometallic complexes for nonlinear optics. 17. Synthesis, third-order optical nonlinearities and two-photon absorption cross section of an alkynylruthenium dendrimer

A soluble, oxidatively and thermally very stable alkynylruthenium dendrimer 1,3,5-C6H3(4-C=C-C6H4C=C-trans-[Ru(dppe)(2)]C=C-3, 5-C6H3-{4-C=CC6H4C=C-trans-[Ru(C=CPh)(dPPe)(2)]}(2))(3), containing a large two-dimensional pi-delocalized system, has been prepared using an experimentally straightforward convergent synthetic approach. The first third-order nonlinear optical (NLO) measurements of an organometallic dendrimer have been. obtained using the Z-scan technique at a wavelength of 800 nm. Progression from 1,3,5-C6H3(4-C=CC6H4C=C-trans-[Ru(dppe)(2)]C=CPh)(3) to the dendrimer results in. (i) no loss of optical transparency, (ii) an increase in the second hyperpolarizability, gamma, which is proportionately greater than, either the increase in the number of phenylethynyl groups or the extinction coefficient for the important MLCT band, and (iii) a dramatic enhancement of two-photon absorption.