## 3 Results and Discussion
### Absorption Properties of New Porphyrazines  
As was stated by [PERSON] et al., the metal ions in the coordination centers and the peripheral substituents strongly influence the electronic absorption spectra of the porphyrinoids [29]. In general, in the spectra of Pzs, two characteristic bands can be observed, the Soret band (B-band) in the range of 300-400 nm and the Q-band in the range of 600-850 nm [29; 30; 31; 32]. The Q-bands that appeared in the spectra of both Pzs **6** and **7** recorded in different solvents are presented in Figure 1. Following the data presented in Table 1, the Soret maxima of **6** and **7** appeared in the ranges of 337-361 and 338-366 nm, whereas the Q-bands were present in the ranges of 681-701 and 682-723 nm, respectively.  
The Q-band positions reflect the effects of \(\pi\)-\(\pi^{\star}\) electron transitions from HOMO (highest occupied molecular orbital) to LUMO (lowest unoccupied molecular orbital) and constitute a characteristic feature of the studied macrocycles. The Q-bands of obtained Pzs **6** and **7** are split into two components, Q\({}_{\text{x}}\) and Q\({}_{\text{y}}\), which could result more from their decreased symmetry than the formation of aggregates. The Soret-band position is also a consequence of \(\pi\)-\(\pi^{\star}\) transitions but from the molecular orbital (MO) to LUMO. The slight modifications of the **6** and **7** peripheries as well as the solvent choice significantly affected the positions of the B- and Q-bands in the UV-Vis spectra. The main difference was the distances between the Q\({}_{\text{x}}\) and Q\({}_{\text{y}}\) components of the Q-bands form, which were approximately 43 nm for **6** and 94 nm for **7** in dichloromethane. In addition, peripheral sulfur atoms could also influence the photophysics of both Pzs. Following the literature, in the magnesium(II) octacarbonanyl(hexylsulfany)porphyrinze UV-Vis spectra, an additional absorption band at approximately 500 nm was noted as a result of n\({}_{\text{sulfur}}\)-\(\pi^{\star}\) transitions [33]. Such phenomena were noted in the spectra of **6** measured in DCM and ethyl acetate and in the spectra of **7** recorded in DCM and acetonitrile.  
\begin{table}
\begin{tabular}{c c c c c} \hline  & \multicolumn{2}{c}{**6**} & \multicolumn{2}{c}{**7**} \\ \hline SOLVENT & \(\lambda_{\text{2}}\)/nm (Soret Band) & \(\lambda_{\text{1}}\)/nm (Q-Band) & \(\lambda_{\text{2}}\)/nm (Soret Band) & \(\lambda_{\text{1}}\)/nm (Q-Band) \\ \hline dichloromethane & 352 & 692 & 358 & 723 \\ acetone & 354 & 685 & 356 & 693 \\ chloroform & 353 & 693 & 357 & 719 \\ diethyl ether & 353 & 685 & 357 & 713 \\ ethyl acetate & 354 & 686 & 355 & 696 \\ acetonitrile & 356 & 686 & 356 & 687 \\ toluene & 361 & 701 & 360 & 707 \\ thf & 355 & 688 & 356 & 689 \\
14-dioxane & 346 & 685 & 357 & 682 \\
**1-butanol** & 347 & 682 & 354 & 683 \\ dmf & 364 & 682 & 366 & 682 \\ dmso & 337 & 681 & 338 & 682 \\ \hline \end{tabular}
\end{table}
Table 1: Soret bands and Q-bands in the UV-Vis spectra of tribenzoporphyrazine derivatives **6** and **7** recorded in various solvents.  
Figure 1: The variation in the Q-band in various solvents for **6** (**a**) and **7** (**b**).