An investigation on geometry and metal interactions in multi metallic porphyrin complexes – EPR studies [microwave power saturation and degree of covalency]

Innovative stylish materials can be synthesized and designed at the molecular level by attaching well characterized and tailored functionalities that have various applications. A
series of meso-tetracuperated porphyrin-Schiff base complexes has been prepared from metallo-5,10,15,20-tetrakis(4-hydroxyphenyl) porphyrins (M = Cu(II), VO(II) and Ni(II)) and salicylideneamino-2-(N,N-dimethylamino)ethane copper(II) perchlorate under a nitrogen atmosphere and their electron paramagnetic resonance (EPR) spectra have been studied. The steric hindrance and electronic effects of the substituted groups and the characteristics of the
different metal ions are the major patrons in inducing the properties of the compounds. From detailed spectral analysis and complete simulation, the results reveal a dipolar interaction between the central copper metal ion of the porphyrin and the meso-copper ions, but no interaction between the vanadyl group and the meso-copper ions. Through studying the EPR properties of these compounds, it is clear that novel EPR oximetry materials can be found and this will help to extend the applications of EPR in vivo.