## 3 Results  
### Platinum Containing Poly(Lactic Acid) Macrocomplex  
Synthesis of bipyridine carboxylic end-capped poly(lactic acid) ligand is an advantageous procedure for the production of several molecular architectures [26]. In this work, the synthesis of Pt(PLLA-Bipy)Cl\({}_{2}\) was reported, according to the scheme reported in Figure 2.  
Synthesis of the ligand with carboxylic end-capped functionalization was proven by the presence of aromatic signals of Bipy in the region between 8.7-7.4 ppm (Figure 3a).  
The formation of the platinum macromplex was detectable by \({}^{1}\)H-NMR spectra, through a comparison of spectra (a) and (b) as reported in Figure 3. The formation of the Pt complex did not affect the number of lactic acid unities in the ligand because the reaction conditions were quite soft. The difference between hydrogen numbers was imputable to several issues: the first and the main relevant among them is the integral processing of the signals that were affected by noise and baseline correction. A% error in integral evaluations was reported in the experimental. Considering these points, the data for the macromplex and the macroligand are in good agreement among them. For a more precise molecular weight and fragment numbers, the value obtained from GPC analysis must be considered. After the coordination of the platinum ion, signals of aromatic hydrogen shifted to a higher ppm (Figure 3b) when compared with the non-coordinated ligand (Figure 3a). This behavior was in agreement with similar results observed for palladium coordination [26]. This phenomenon is due to the reduction of charge density on the aromatic ring caused by the modification of the \(\pi\)-orbitals of the Bipy due to the interaction of the electron doublet on the nitrogen atoms with the platinum orbital system as described by several theoretical studies [27; 28]. Thermal properties of the complex were in good agreement with those previously reported for functionalized poly(lactic acid) [29].  
\begin{table}
\begin{tabular}{l l l l l l l l l l l l l} \hline \hline \multirow{2}{*}{**Run**} & \multirow{2}{*}{**Cat**} & \multirow{2}{*}{**Substrate**} & \multicolumn{2}{c}{**Time**} & \multicolumn{2}{c}{**Pressure**} & \multirow{2}{*}{**1 [\%]**} & \multicolumn{2}{c}{**II**} & \multicolumn{2}{c}{**III**} & \multicolumn{2}{c}{**IV**} & \multicolumn{2}{c}{**V**} & \multicolumn{2}{c}{**VI**} & \multicolumn{2}{c}{**Conversiona **} & \multicolumn{2}{c}{**TOFb **} \\ \hline
**ID1** & A & 3 & 1.1 & 100 & 0 & 0 & - & - & - & - & - \\
**ID2** & B & & 3 & 1.1 & 27 & 73 & 0 & - & - & 73 & 243 \\
**ID3** & B & & 6 & 1.1 & 1 & 99 & 0 & - & - & - & 99 & 165 \\
**ID4** & B & & 3 & 1.1 & 61 & 39 & 0 & - & - & - & 39 & 130 \\
**ID5** & B & & 3 & 2.2 & 5 & 95 & - & - & - & - & 95 & 317 \\
**ID6** & B & & 3 & 2.2 & 60 & 40 & - & - & - & - & 40 & 133 \\
**ID7** & B & & 3 & 2.2 & - & - & - & 4 & 8 & 88 & 96 & 320 \\
**ID8** & B & & & 6 & 2.2 & - & - & - & 3 & 8 & 89 & 97 & 161 \\
**ID10** & B & & & H & 3 & 2.2 & - & - & - & 9 & 4 & 87 & 91 & 303 \\ \hline \hline \multicolumn{10}{l}{a **} \\ \hline \hline \end{tabular}
\end{table}
Table 1: Catalytic performances of Pt(Bipy)Cl\({}_{2}\) (A) and Pt(PLLA-Bipy)Cl\({}_{2}\) (B) in the selective hydrogenation of 2-cyclohex-1-one (I) and (E)-but-2-real (IV) at 60 \({}^{\circ}\)C.  
Figure 2: Pathway for the synthesis of Pt(PLLA-Bipy)Cl\({}_{2}\) macrocomplex.  
The effect of orbitals interactions was also appreciable in the UV-Vis spectra reported in Figure 4. Pt(PLLA-Bipy)Cl\({}_{2}\) (c) and Pt(Bipy)Cl\({}_{2}\) (a) showed a maximum absorption at 287 nm and a secondary absorption at 314 and 384 nm while PLLA-Bipy (b) showed only the absorption at 287 nm. Additional absorption bands were an evident proof of the coordination of Pt to Bipy moieties, in agreement with the NMR spectra above reported.