Synthesis and separation of the constitutional isomers of 1(4),8(11),15(18),22(25)-tetrakis[(pentyloxycarbonyl)phenoxy]-phthalocyaninato zinc(II) complexes
作者:Ming Bai、Yan Zhang、Rui Song、Senjian Han、Peihong Wan、Chongxi Zhang
DOI:10.1016/j.dyepig.2013.01.016
日期:2013.6
Cyclic tetramerization of 3-[(methyloxycarbonyl)phenoxy]phthalonitrile (1a-1c) in the presence of Zn(OAc)(2)center dot 2H(2)O and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) followed by transesterification in refluxing n-pentanol afforded 1(4),8(11),15(18),22(25)-tetrakis[(pentyloxycarbonyl)phenoxy]phthalocyaninato zinc(II) complexes (2a-2c) as a mixture of four constitutional isomers. Simple silica-gel column chromatography leads to the successful separation of pure isomers with the C-4h and D-2h symmetry together with a section containing the C-2v and C-s isomers, which have been characterized with a wide range of spectroscopic methods including MALDI-TOF mass, electronic absorption, H-1 NMR, and 2D COSY spectroscopy. Synthesis yields in combination with the NMR spectroscopic results reveal that the distribution of the four isomers in the final product for 2a-2c does not strictly follow that expected according to statistical calculation with the ratio of C-4h:C-2v:C-s:D-2h = 1:2:4:1, indicating the effect of steric hindrance of substituents on the formation of various constitutional isomers. (C) 2013 Elsevier Ltd. All rights reserved.