Synthesis and separation of the constitutional isomers of 1(4),8(11),15(18),22(25)-tetrakis[(pentyloxycarbonyl)phenoxy]-phthalocyaninato zinc(II) complexes
摘要:
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.
Synthesis and separation of the constitutional isomers of 1(4),8(11),15(18),22(25)-tetrakis[(pentyloxycarbonyl)phenoxy]-phthalocyaninato zinc(II) complexes
摘要:
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.