The synthesis and properties of unsymmetrical porphyrazines annulated with a tetrathiafulvalene bearing two tetraethylene glycol units

A dicyano-tetrathiafulvalene precursor was prepared by the cross-coupling reaction of 4,5-dicyano-1,3-dithiol-2-one with 4,5-bis(3,6,9,12-tetraoxatridecylthio)-1,3-dithiol-2-thione. A Mg(II) template cyclization of the precursor with excess 2,3-bis(methylthio)maleonitrile gave the unsymmetrical magnesium porphyrazine, which was easily converted to the metal-free derivative by treatment with acetic acid in the dark. The metal-free porphyrazine was converted to the corresponding zinc porphyrazine in 75% yield. The products were fully characterized using spectroscopic data and elemental analysis. They were soluble in common organic solvents; solution electrochemical, UV–Vis and ESR data revealed that all porphyrazines formed an electron transfer complex with 7,7,8,8-tetracyanoquinodimethan and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane.