Synthesis and third-order optical nonlinearities of hyperbranched metal phthalocyanines

A series of novel organic hyperbranched metal phthalocyanines (HMePcs) oligomers were synthesized for investigating their third-order nonlinear optical (NLO) properties. The third-order NLO coefficient was measured by Z-scan technique with a pulsed Q-switched Nd:YAG nanosecond laser at 532   nm. The HMePcs showed large molecular cubic hyperpolarizabilities ( γ ) whose values were of the order of 10 −29   esu. The variation of substituent groups of and center metal of HMePcs influenced the third-order optical nonlinearity. The presence of electron-withdrawing substituents-fluoro in the phthalocyanine brings about a noticeable improvement of the third-order nonlinear susceptibility χ (3) in these systems and the third-order nonlinear susceptibility χ (3) values of different metal hyperbranched metal (Cu, Ni, Co) phthalocanines oligomers were found to decrease in the order HCuPc   >   HNiPc   >   HCoPc.