Synthesis, Conductivity, and Impedance Studies on Metallophthalocyanines Formed Across Adjacent Rings

The synthesis and characterization of Co^II, Zn^II, and Ni^II phthalocyanines (Pcs) 4, 5, and 6, respectively, containing two bis[2-(4-hydroxyphenyl)-2-propyl]benzene groups formed across adjacent rings at the peripheral positions are described. The Pcs were synthesized by cyclotetramerization of the previously prepared precursor 4,4′-bis[1,3-propylbenzene-2-p-phenoxy]phthalonitrile (3) in the presence of metal salt in boiling dry DMF under a dry nitrogen atmosphere. Elemental analysis, UV-Vis, FT-IR, and ¹H-NMR spectroscopy, as well as MALDI-TOF mass spectrometry techniques were used for the characterization of 4. Conductivity (dc and ac) and impedance spectroscopy (IS) measurements were performed on the films of 5 and 6 between the temperatures 293 and 523 K and frequencies 40 and100 kHz. The dc conductivity values were calculated as 2.11 × 10–¹⁰, 3.48 × 10–¹⁰, and 1.90 × 10–¹⁰ S/cm for the films of 4, 5, and 6, respectively, at room temperature. Activation energy values of the films were also calculated. Conductivity (ac) results suggest that the dominant charge transport mechanisms can be explained by the hopping model depending on temperature and frequency range. From impedance spectra and Cole-Cole plots, the relaxation time in the Debye dispersion relation is considered as a distribution of relaxation time values rather than as a single relaxation time. To elucidate the structural, spectroscopic, and bonding properties of the obtained compounds, DFT/TD-DFT calculations were performed.