## 3 Results and Discussion
### Electrochemical Studies  
The electrochemical measurements were performed using two zinc(II) tribenzoporphyrazine derivatives, **6** and **7**, to assess their electroactivity towards potential uses as semiconductors or electrocatalys. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studies were applied in the classic three-electrode system with the glassy carbon working electrode, a platinum wire as a counter electrode, and a silver wire as a pseudo-reference. Due to the insolubility of Pzs **6** and **7** in water, the measurements were performed in dichloromethane with the addition of a tetrabutylammonium perchlorate (TBAP) electrolyte (0.1M). Ferrocene was used as an internal standard, and all voltammograms were adjusted to the ferrocenium/ferrocene peak potential. The CV scans were performed in the range of 25-200 mV/s. In the voltammogram of **6**, two reduction peaks and one oxidation peak were observed in the electrochemical window between \(-2.0\) V and \(+1.0\) V. The second oxidation peak was not noted in the CV scans (Figure 4a). However, its evolution was observed at the boundary of the electrochemical window in the DPV scan (Figure 4b). All redox peaks were correlated with the oxidation or reduction of the macrocycle ring due to the presence of the electrochemically inactive zinc(II) cation inside the core. The CV and DPV studies of **7**, which is a reduced derivative of Pz **6**, revealed four redox peaks: two reductions and two oxidations in the investigated potential window (Figure 5). Within the first reduction peak, an additional descending peak can be observed related to the aggregation phenomenon of the studied porphyrazine, which is commonly observed in the voltammograms of other porphyrinoids in dichloromethane. The electrochemical data of Pzs **6** and **7** are presented in Table 3. A positive shift of 0.1 V of peak potentials for Pz **7** compared to Pz **6** was noticed. It may be a result of replacing electron-withdrawing groups (ester groups) with electron-donating groups (hydroxymethyl groups). In both cases, the electrochemical bandgap, Egap, presented the same value of 1.5 eV. The obtained electrochemical data for Pz **6** were compared to its symmetrical analogue, an octasubstituted porphyrazine synthesized previously by our group [36], which was previously subjected to CV and DPV measurements in the same conditions as presented here. For the symmetrical zinc(II) sulfanyl porphyrazine with peripheral isophthaloxybutyl-sulfanyl substituents, the first reduction peak occurred at \(-1.01\) V, while the first oxidation was noted at 0.67 V [36]. Considering this data, the redox processes were positively shifted in the symmetrical derivative, and the electrochemical bandgap was slightly higher in comparison to the unsymmetrical macrocycle **6** as a result of the presence of more electron-withdrawing ester groups in the macrocycle. Another example constitutes a symmetrical zinc(II) sulfanyl porphyrazine with (morpholin-4-yl)ethyl peripheral groups, which was \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Solvent** & **Refractive** & **Dipole Moment** & **Q-Band** & **Q-Band** \\
**Index (n\({}_{\text{D}}\))** & **(\(\upmu\))** & **(\(\mathbf{\Omega_{max}}\) nm) 6** & **(\(\mathbf{\Omega_{max}}\) nm) 7** \\ \hline
**dichloromethane** & 1.445 & 1.60 & 692 & 723 \\
**acetone** & 1.359 & 2.88 & 685 & 693 \\
**chloroform** & 1.446 & 1.04 & 693 & 719 \\
**diethyl ether** & 1.352 & 1.15 & 685 & 713 \\
**ethyl acetate** & 1.372 & 1.78 & 686 & 696 \\
**acetonitrile** & 1.344 & 3.92 & 686 & 687 \\
**toluene** & 1.497 & 0.37 & 701 & 707 \\
**THF** & 1.407 & 1.75 & 688 & 689 \\
**1,4-dioxane** & 1.422 & 0 & 685 & 682 \\
**1-butanol** & 1.399 & 1.66 & 682 & 683 \\
**DMF** & 1.430 & 3.82 & 682 & 682 \\
**DMSO** & 1.478 & 3.96 & 681 & 682 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The variation in the Q-band for **6** and **7** in different solvents (dipole moments and refractive indexes [24; 35]). studied in DCM/0.1M TBAP with ferrocene as an internal standard.