Nano-híbridos baseados em complexos de ftalocianina derivados do cardanol, óxido de grafeno e magnetita

Abstract

The phthalocyanines are synthetic macromolecules made up of planar heterocycles formed by four isoindole units linked by nitrogen through a nitrogen bridge. The aromatic rings of the macrocycle give the compound high density electronics due to one π conjugated system of 18 electrons. The main properties of phthalocyanines are: high thermal stability, photoconductivity, electric semiconduvidade, highly conjugated electronic structure, low solubility in a wide variety of organic solvents. This set allows its use and application; including its metal analogues in various industries like paint industry and pigments, photosensitizers, electronic sensors, photo catalysis, photodynamic therapy, photovoltaics, semiconductor and electronic systems that operate at low frequencies. Thus, aiming to make the most of optical and electrical properties of this class of molecules, this paper proposes synthesizing phtalocyanines derived from cardanol, the main by-product of agribusiness cashew nuts, and combines them with graphene oxide, material of high performance, doped with magnetic nanoparticles, producing new nanomaterials with high dielectric property. The phthalocyanines have been synthesized by two routes: conventional route and microwave irradiation. This one showed the highest yields compared the conventional method of 14.70; 9.59; 111.42 and 14.54% for the metallated phthalocyanines with Co, Cu, Ni and Zn, respectively. The products were characterized by the techniques 1H NMR, GC-MS, UV-Vis, FT-IR and TGA. The nanohybrids were characterized by FT-IR, TGA, DSC, their dielectric properties were verified by impedance spectroscopy and the magnetic behavior by hysteresis. For all nanomaterials studied, significant improvements were observed in the dielectric properties of nanohybrids when compared with the complexes analyzed separately. The magnetization values obtained for the hybrid materials were slightly lower than those of the pure magnetite. The lowest value found was 42 emu • g-1 (GO@Fe3O4/CoPc)) and 53.48% for GO@Fe3O4/NiPc. The nano-hybrids OG @Fe3O4/[Cu(Pc)] showed an increase in the values of permittivity and conductivity of 1,2 – 627 and 1.5 x 10-7 – 1.8 x 10-4 Ω-1 m-1. Therefore there was a real increase in the properties of de 5.2 x 104% (ε'r) e 2.7x 107 (σ)