Holmium porphyrin compound liquid crystals: Synthesis and properties

摘要

5,10,15,20-Tetra-[(p-alkoxy-m-ethyloxy)phenyllporphyrin and [5-(p-alkoxy)phenyI-10,15,20-tri-phe-nyl]porphyrin and their holmium(III) complexes are reported. They display a hexagonal columnar dis-cotic columnar (Col_h) liquid crystal phase and were studied by cyclic voltammetry, surface photovoltage spectroscopy (SPS), electric-field-induced surface photovoltage spectroscopy (EFISPS) and luminescence spectroscopy. Within the accessible potential window, all these compounds exhibit two one-electron reversible redox reactions. Quantum yields of Q band are in the region 0.0045-0.21 at room temperature. The SPS and EFISPS reveal that all the compounds are p-type semiconductors and exhibit photovoltaic response due to pi-pi* electron transitions.