Synthesis,Characterization And Properties Of Novel Porphyrin Liquid Crystals With Long Chains

Porphyrin compounds are widely distributed in nature,and are essential compounds in life processes.Porphyrin derivatives have received considerable attention because of their particular structure and unique physical and chemical properties.They have played an important role in the field of biological chemistry,medical chemistry,analytical chemistry,synthetic chemistry,material chemistry,etc.In recent years,porphyrin liquid crystals have been used in the field of information storage,liquid crystal display,and nonlinear optical material.In this paper,three series of porphyrin compounds(37 compounds altogether)with long arms were synthesized by multi-step reaction with simple compound as starting substance.These compounds have different substituent group or length,which are:five5,10,15,20-tetra[3,4,5-tri(alkylacyloxy)phenyl]porphyrin ligands and ten metal complexes;five 5,10,15,20-tetra[3,5-di(alkylacyloxy)phenyl]porphyrin ligands and ten metal complexes;seven 5,10,15,20-tetra[3,4,5-tri(octanoyloxy)phenyl]porphyrin metal complexes.There compounds were characterize by elemental analysis,UV-Vis absorption spectra,infrared spectra,and ~1HNMR.The photochemical properties of porphyrin ligands and their metal complexes were studied by fluorescence spectra andUV-Visabsorptionspectra,andthefluorescencelifetime and fluorescence quantum yield were also calculated.The thermal stability was studied by Thermogravimetric analysis(TGA)and the liquid crystal properties of compounds were studied by Differential Scanning Calorimetry(DSC)and polarizing microscope.We also studied the influence of chain length and metal coordination on the properties of porphyrin liquid crystals.The study shows that 10 of the 15 compounds in the first series have liquid crystal property.They exhibit 1 to 3 intermediate phases,the phase transition temperatures are low and phase transitions are in the range of 2.2-72.4?.Only 5 of 15 porphyrin compounds of the second series are liquid crystalline compounds,which exhibit 1 to 3intermediate phases.The phase transition temperature increased,and the phase change in the range of 23.0-101.0?.Study show that among the 7 metal complexes of the third series,only 2(Cd and Ni)compounds exhibite liquid crystal properties.Cadmium porphyrin complex has two liquid crystalline phases when heated or cooled.Nickel porphyrin complex has only one liquid crystalline phase when heated,and two liquid crystalline phases in the cooling phase.The phase transition temperature is not high,and the phase transition range is at 5-39.4?.