Green synthesis and characterization of crystalline zinc phthalocyanine and cobalt phthalocyanine prisms by a simple solvothermal route

Abstract

A facile, environmentally-friendly and low-cost method for one-step synthesis of zinc phthalocyanine (ZnPc) and cobalt phthalocyanine (CoPc) prism-shaped crystals was proposed. The well-defined crystalline prisms (ZnPc, up to 8 mm and CoPc, more than 1 mm) can be grown during a solvothermal process at 160 °C for 6 h. It is noted that ethanol (pentanol or benzyl alcohol) was used as the reaction medium and no surfactants or other chemical additives were used in this preparation. To the best of our knowledge, this is the first report on the green and direct synthesis from simple raw materials to large ZnPc and CoPc crystals with high quality. Compared to the traditional preparation of MPc solids and their re-crystallization purification by using H₂SO₄, our method is very convenient, safe and time-efficient. The complete characterization, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), single crystal X-ray diffraction, powder X-ray diffraction, and Fourier transform infrared (FT-IR) and Raman spectrometry, was performed to measure the molecular structures, crystal structures, and surface morphologies. The highly predominant crystal face of ZnPc crystals was determined to be (100) and the probable crystal growth mechanism was proposed. Moreover, the thermal and photoelectric measurements of ZnPc and CoPc crystals show their excellent thermal stability and photoelectric transformation performance, respectively.