Solvothermal growth of manganese phthalocyanine quadrangular crystals on Mn slice in ethanediol medium

Exploring the practical method to grow high quality metal phthalocyanine (MPc) crystals and understanding their growth mechanism is significant for their applications. In this study, manganese phthalocyanine (MnPc) crystals were successfully synthesized using simple substance Mn and dicyanobenzene in the reaction medium of ethanediol without any other chemical reagents. The well shaped quadrangular MnPc crystals more than 500 μm were in situ grown on Mn slice surfaces via a simple solvothermal reaction. XPS analyses show that Mn has the mixed chemical state of +3 and + 4 in MnPc. Ethanediol acted as not only the solvent but also acidic catalyst to boost the ionization of dicyanobenzene. Different from the reported synthesis of MPc crystals, MnPc crystals could be formed at a wide temperature range of 100–190 °C. The reaction time is the only experimental parameter to regulate the crystal growth. To the best of our knowledge, this is the first report on in situ synthesis of the high quality MnPc crystals on Mn substrate by using a simple solvothermal method.