Dipole Moment of Ni(II), Cu(II), AND Zn(II) Porphyrins and Out of Plane Distortions Quantified by Semiempirical Methods and Compared to Thin Layer Chromatography

Dipole Moment of Ni(II), Cu(II), AND Zn(II) Porphyrins and Out of Plane Distortions Quantified by Semiempirical Methods and Compared to Thin Layer Chromatography

The objective of this experiment was to calculate the dipole moment of Ni(II), Cu(II), and Zn(II) porphyrins and relate the measurements to the Thin Layer Chromatography (TLC) experimental results. Tetraphenylporphyrin (TPP) and Octaethylporphyrin (OEP) were metallated with these transition metals (Ni(II) d8, Cu(II) d9, and Zn(II) d10). The results of the TLC were then further compared to the dipole moment from calculations obtained using semi-empirical methods. It is known that different transition metals can expand or contract the core of these porphyrins due to electronic effects as well as size. The TPP series follows the trend of the dipole moment, correlating to the semi-empirical calculations. The Cu(II) OEP and Ni(II) OEP did not follow the experimental trend of the dipole moment calculations, however the Zn(II) OEP did follow the trend. The reasons for the inconsistency of the Cu(II) OEP and Ni(II) OEP may be the result of different conformations of the porphyrin skeleton, inductive effects of the peripheral substituents or unique splitting of the d orbital electrons of the metals.