Synthesis, Langmuir-Blodgett Film, and Second-Order Nonlinear Optical Property of a Novel Asymmetrically Substituted Metal-Free Phthalocyanine
Anovel asymmetrically substituted, soluble, metal-free phthalocyanine with only one reactive nucleophilic substituent of aminewassynthesized for 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, 1H 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 I2ωp→p and I2ωs→p are 1.97 x 10-6 and 1.71 x 10-7, respectively. The second-order susceptibility (x(2)) and the molecular hyperpolarizability (β) values of the monolayer are 3.33 x 10-8 and 5.90 x 10-30 esu, respectively.