Photophysical and non-linear optical behavior of novel tetra alkynyl terminated indium phthalocyanines: Effects of the carbon chain length

We report on the synthesis, photophysical and nonlinear optical behavior of tetra-substituted alkynyl indium phthalocyanine complexes (3a and 3b). Both complexes showed large triplet quantum yields. Nonlinear optical properties were also evaluated for the two complexes at a wavelength of 532 nm using nanosecond Z-scan technique in dimethylsulfoxide. We observed two-photon absorption (2PA) and strong reverse saturable absorption (RSA) as the dominant mechanisms at nanosecond laser excitation. The underlining 2PA and observed RSA were subjected to further scrutiny by comparing the analytical absorption model to the transmittance optical absorption theory. The theoretical results were in good agreement to the observed RSA and the 2PA mechanism. Large two-photon absorption cross-section (1.29 × 10−42 and 1.15 × 10−42 cm4 s/photon), third-order susceptibility (2.10 × 10−14 and 2.15 × 10−14 esu) and hyperpolarizability (2.70 × 10−32 and 3.19 × 10−32 esu) were estimated for complex 3a and 3b, respectively.Original publication is available at http://dx.doi.org/10.1016/j.poly.2014.12.02