# Naphthalene-Based Polymers as Catalytic Supports for Suzuki Cross-Coupling
## 2 Results  
### Characterization of the Polymers  
#### 2.1.1 Liquid Nitrogen Physisorption and DRIFTS  
The liquid nitrogen physisorption revealed that synthesized NA-based polymers are mainly micro-mesoporous with predominant microporosity; SSA\({}_{\text{BET}}\) varied from 757 m\({}^{2}\)/g up to 1065 m\({}^{2}\)/g (see Table 1 and Figure 2). It is noteworthy that with the increase in methylal amount from 15 mmol up to 120 mmol, the SSA\({}_{\text{BET}}\) went through a maximum at 30 mmol (Figure 2d), while the relative micropore volume in the case of NA30 had the lowest value. Figure 1: General scheme of the synthesis of NA-based polymers and their further modifications. 3650 cm\({}^{-1}\) refers to vibrations of the OH-groups of the polymer and water, which did not form hydrogen bonds. A broad band with the maximum at about 3530 cm\({}^{-1}\) corresponds to stretching vibrations of OH-groups belonging to carboxyl groups that formed hydrogen bonds. Bands at 1607 and 1500 cm\({}^{-1}\) refer to stretching vibrations of C-C bonds in aromatic rings. The band at 1370 cm\({}^{-1}\) likely refers to deformation vibrations of CH\({}_{3}\)-groups. There are numerous absorption bands, which correspond to oxygen-containing species: bands at 1770, 1725, and 1700 cm\({}^{-1}\) refer to stretching vibrations of \(>\)C=O belonging to keto- and carboxyl groups, namely Ar-O-C(O)-R, Ar-C(O)-O-R, and Ar-COOH [29; 30]. For hyper-crosslinked polystyrene, [PERSON] et al. [31] suggested that the absorption bands in the region of 1740-1600 cm\({}^{-1}\) can be attributed to hindered vibrations of C-C bonds and bond angles in benzene rings. However, in the case of NA-based polymers synthesized in this work, we can also observe several strong bands of stretching vibrations of C-O bonds belonging to ester and also ether groups, i.e., 1267 cm\({}^{-1}\) (Ar-C(O)-O-R), 1190 cm\({}^{-1}\) (Ar-O-C(O)-R), and 1105 cm\({}^{-1}\) (Ar-O-CH\({}_{2}\)-R). In the range of 1460-1420 cm\({}^{-1}\), in-plane bending vibrations of CH\({}_{2}\)-groups belonging to Ar-CH\({}_{2}\)-Ar and Ar-CH\({}_{2}\)-OH can be found. If we take a closer look at the region of 2960-2800 cm\({}^{-1}\) (Figure 3b), we will find several absorption bands of stretching vibrations of C-H bonds in CH\({}_{2}\)-groups belonging to Ar-CH\({}_{2}\)-Ar and Ar-CH\({}_{2}\)-OH, all of which are the result of methylal binding to the rings of NA. The intense absorption band at 2924 cm\({}^{-1}\) was chosen to determine if there is any dependence between its signal (in K-M units) and the amount of methylal used for the polymers' synthesis (Figure 4). As can be seen, the increase in methylal amount from 15 mmol up to 60 mmol results in a corresponding linear increase in its binding to NA monomers. It is noteworthy that the amount of bonded methylal does not reflect the degree of the polymer crosslinking (groups Ar-CH\({}_{2}\)-Ar between neighboring chains), since methylal also participates in the formation of oxygen-containing moieties. Additionally, SSA\({}_{\text{BET}}\) decreased with the increase of methylal amounts higher than 30 mmol (see Figure 2d) in accordance with the data of DRIFTS. When the amount of methylal is higher than 60 mmol, a relative decrease in the signal of the absorption band at 2924 cm\({}^{-1}\) is seen; this can be due to an excessive amount of unreacted methylal. While adding the methylal to the NA-containing solution, fast gelation occurred, after which the mass transfer through the forming dense polymer layer was  
Figure 3: Normalized IR-spectra of NA-based polymers obtained at variations of methylal amount (**a**); scaled up region of the polymers’ spectra in the range of 3200–2600 cm\({}^{-1}\) (**b**). hindered, in spite of mixing, and the excessive amount of methylal could not penetrate into the reaction volume. The functionalized polymers (NL60, NNA120, and SNA120) were also studied by liquid nitrogen physisorption and DRIFTS.