## 3 Results and Discussion
### Synthesis of MIP on Terbium Nitrate
#### 3.2.1 Yield of the Products  
The yield of the reaction product is the ratio of the mass of the resulting product to the mass that should theoretically be obtained. The theoretical mass of the copolymers was taken as the total mass of the monomers used (Table 5). The yield of the products was calculated by the following formula:  
\[\omega=\frac{m_{pract. }}{m_{tho  
Figure 5: MIPs and NIPs after freeze-drying: (a) MIP of terbium; and (b) NIP of terbium. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample** & **Mass of MAA, g** & **Mass of 2-VP, g** & **Total Mass, g** \\ \hline MIP of Tb & 0.237 & 0.289 & 0.526 \\ NIP of Tb & 0.237 & 0.289 & 0.526 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Theoretical mass of the products. Yield of the MIP of terbium:  
\[\omega=\frac{0.312}{0.526}\times 100\%=59.3\%\]  
Yield of the NIP of terbium:  
\[\omega=\frac{0.325}{0.526}\times 100\%=61.2\%\]  
As can be seen from the calculations, the yield of the products ranged from 59 to 62 percent, which is an average value. A possible reason why the yield was not more than 80 percent is because there is a possibility that active polymerization did not take place everywhere. The ratio of the monomers was taken based on the literature data and previously performed experiments on metals. Such an output is due to the fact that not all the monomers were able to enter the pre-polymerization complex. Accordingly, less product was obtained. The difference between the MIP and NIP yields was around 3%, and the mass of the NIP final product was slightly larger than the MIP. This can be explained by the fact that not all the monomers were able to bind and form a pre-polymerization complex due to the steric effect, and the formed pre-polymerization complexes could not turn into MIP. Also, another reason could be that the synthesis of the MIP may occur under conditions that are not always ideal for obtaining a high yield of the product. Various factors, such as the temperature and reaction time, can affect the yield of the product and lead to a low yield. Since MIPs contain molecular imprints, they have a complex three-dimensional structure. During the synthesis process, MIP particles can bind to each other or to other particles of the material, which can lead to a decrease in the particle size and, as a consequence, to a decrease in the polymer yield. Thus, the yield of the MIPs may be less than the theoretical yield due to various factors listed above. The obtained imprinted polymer structures were analyzed by IR spectroscopy, the results are shown in Figure 6 and the description is provided in Table 6.  
According to the obtained IR spectra (Figure 6) of the MIP and NIP on terbium(III) nitrate, the following description can be offered. A broad intensive band is observed at 3246.44 and 3293.79 cm\({}^{-1}\) for both samples. It could be defined as OH- groups; more exactly, intra- and intermolecular hydrogen bonding in the polymers. The valence oscillation of the -CH\({}_{2}\)- group is usually in the form of several either weak or variable-intensity bands with a wavenumber of 2956.93 cm\({}^{-1}\) for Tb-MIP and 2918.33 cm\({}^{-1}\) for NIP. For both samples, bands relative to the carboxylic group in MAA could be found on the IR spectrum: -COO' \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Functional Group**} & **Wavenumber, cm\({}^{-1}\)** & **Wavenumber, cm\({}^{-1}\)** & **Wavenumber, cm\({}^{-1}\)** \\  & **(Theoretical Data) [70]** & **(MIP)** & **(NIP)** \\ \hline -OH & 3400–3200 & 3246.44 & 3293.79 \\ \hline -CH\({}_{2}\)- & 2940–2915 & 2926.67 & 2918.33 \\ \hline -COO’ & 1650–1550 & 1597.10 & 1601.07 \\ \hline -CH\({}_{2}\)-CO- & 1440–1400 & 1407.65 & 1406.63 \\ \hline Pyridine ring & 1100–1000 & 1027.51 & 1026.89 \\ \hline
1,3-substitution & 900–860 & 885.09 & 891.61 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Characteristics of the IR spectrum frequencies for terbium(III) nitrate.