Synthesis and EPR studies of porphyrazines with bulky substituents

Abstract

Magnesium porphyrazinate substituted with eight 4- tert-butylphenylthio-groups on the peripheral positions has been synthesized by cyclotetramerization of 1,2-bis(4- tert-butylphenylthio)maleonitrile in the presence of magnesium butanolate. The metal-free derivative was obtained by its treatment with trifluoroacetic acid and further reaction of this product with copper(II) acetate, zinc(II) acetate and cobalt(II) acetate led to the metal porphyrazinates (M = Cu, Zn, Co). These new compounds have been characterized by elemental analysis, together with FT-IR, 1H NMR, UV–Vis spectral data. By using EPR technique, room temperature paramagnetic properties of Cu(II) doped porphyrazine sample as powder and solution forms were measured. The first-derivative EPR signals taken from as powder and solution forms shows that the sample is axially symmetric. The trend g ∥ > g ⊥ > 2 indicates that the unpaired electron is located mainly in the d x 2 - y 2 orbital ( 2B 1 as ground state).