Synthesis, Langmuir-Blodgett film, and second-order nonlinear optical property of a novel asymmetrically substituted metal-free phthalocyanine

A novel asymmetrically substituted, soluble, metal-free phthalocyanine with only one reactive nucleophilic substituent of amine was synthesized fur the first time by reduction reaction with sodium sulfide nonahydrate of the nitro group in nitrotri(tert-butylphthalocyanine, which was prepared by mixed condensation of two corresponding diiminoisoindolines. The compound can be separated by common column chromatography either on neutral Al2O3 using chloroform/hexane as the eluting solvent or on silica gel using chloroform as the eluent. The structure was confirmed by elemental analysis, H-1 NMR, UV-vis, IR, and mass spectroscopy. Thermostability of the compound was checked by thermogravimetry analysis. Langmuir-Blodgett films of the compound were fabricated, and the configuration of the phthalocyanine molecules at the air-water interface was suggested in terms of the limiting area per molecule. Second-harmonic generation (SHG) from monolayer and multilayers was measured, The SH intensities of the monolayer relative to a Y-cut quartz wedge I-2 omega(p-p) and I-2 omega(s-p) are 1.97 x 10(-6) and 1.71 x 10(-7), respectively. The second-order susceptibility (chi((2))) and the molecular hyperpolarizability (beta) values of the monolayer are 3.33 x 10(-8) and 5.90 x 10(-30) esu, respectively.