Novel Pathway to Synthesize Unsymmetrical 2,3,9,10,16,17,23-heptakis(alkoxyl)-24-mono(dimethylaminoalkoxyl)phthalocyanines

• Published in: Inorganic chemistry 2010-10, Vol.49 (19), p.9005-9011
• Main Authors: Bai, Zhaopin, Gao, Yingning, Zhu, Peihua, Bian, Yongzhong, Jiang, Jianzhuang
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic101362y

A new pathway by means of transetherification has been developed to synthesize novel unsymmetrical 2,3,9,10,16,17,23-heptakis(alkoxyl)-24-mono(dimethylaminoalkoxyl)phthalocyanine compounds. Cyclic tetramerization of 4,5-di(alkoxyl)phthalonitrile in refluxing dimethylamino-alcohol with high boiling point such as dimethylaminoethanol (DMAE) and 1-dimethylamino-2-propanol in the presence of lithium and pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile followed by treatment with acetic acid led to the isolation of a series of unsymmetrical metal free 2,3,9,10,16,17,23-heptakis(alkoxyl)-24-mono(dimethylaminoalkoxyl)phthalocyanine compounds H2{Pc(OR)7[OR′N(CH3)2]} [R = C4H9, C5H11, C8H17 and R′ = C2H4; R = C4H9 and R′ = CH(CH3)CH2] (1−4). Metal insertion into unsymmetrical metal free phthalocyanines (Pc's) using Cu(OAc)2·H2O in dimethylformamide (DMF) at 140 °C easily afforded corresponding unsymmetrical phthalocyaninato copper complexes Cu{Pc(OR)7[OR′N(CH3)2]} (5−8) in good yields. These novel unsymmetrical phthalocyanine compounds have been characterized by a series of spectroscopic methods including 1H NMR, electronic absorption, IR, and mass spectroscopy in addition to elemental analysis. Their electrochemistry was also studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The present result will be helpful for designing and preparing unsymmetrical phthalocyanines with potential applications in dye-sensitized solar cells.