Organometallic Complexes for Non-linear Optics. 49.* Third-Order Non-linear Optical Spectral Dependence Studies of Arylalkynylruthenium Dendrimers

The cubic hyperpolarizabilities of 1,3,5-(trans-[RuCl(dppe)(2)(C CC6H4-4-C C)])(3)C6H3 (1), 1,3,5-(trans-[Ru(C CPh) (dppe)(2)(C CC6H4-4-C C)])(3)C6H3 (2), 1,3,5-(trans-[ Ru(C CC6H4-4-NO2)(dppe)(2)(C CC6H4-4-C C)])(3)C6H3 (3), 1,3,5-{trans-[Ru(C C-3,5-(trans-[Ru(C CPh)(dppe)(2)(C CC6H4-4-C C)])(2)C6H3)(dppe)(2)(C CC6H4-4-C C)]}(3)C6H3 (4), and 1,3,5-{trans-[Ru(C C-3,5-(trans-[Ru(C CC6H4-4-NO2)(dppe)(2)(C CC6H4-4-C C)])(2)C6H3)(dppe)(2) (C CC6H4-4-C C)]}(3)C6H3 (5) have been assessed over the spectral range 520-1600 nm using the Z-scan technique and similar to 150 fs pulses. All complexes exhibit negative values of gamma(real) (corresponding to self-defocusing behaviour) and significant positive values of gamma(imag) (corresponding to two-photon absorption) at short wavelengths (up to 1000 nm). The maximal values of gamma(real) and gamma(imag) increase in magnitude on dendrimer generation increase (proceeding from 2 to 4 or 3 to 5). The open-aperture Z-scan results have been used to confirm and contrast the two-photon (2PA) and three-photon absorption (3PA) behaviour of 1-5, the data being consistent with the existence of 2PA at the short wavelength range, but with significant 3PA at longer wavelengths for 1-3 and 5, a record 3PA coefficient for an inorganic complex for 5 at 1180 nm, and appreciable 3PA at the telecommunications wavelength of 1300 nm.