## 3 Results
### Estimation of Photocatalytic Activity of Composites PMMA + ((1)-(5))  
The photocatalytic activity of composites containing titanium(IV)-oxo complexes and ruthenium(III) complexes was assessed by monitoring changes in the decolorization of MB and CV solutions under UV irradiation and MB under visible light (Vis) (Figures S5-S7 and Tables S4-S6). The study focused on MB and CV dyes, as these were the most readily absorbed by the tested composites. Figure 6 presents representative changes in the decolorization percentages of MB (Vis and UV) and CV (UV) using the PMMA + (3) composite. Figure 7 illustrates the changes in the observed rate constants (h\({}^{-1}\)) for MB solution decolorization relative to PMMA for PMMA + (1)-(5) composites exposed to Vis and UV light (measurement data provided in Figures S5 and S7 and Tables S4 and S6). Meanwhile,  
Figure 5: Percentage reduction of the concentration of the studied group of dyes by PMMA composites with complexes (1)-(5). For clarity, results are shown for systems containing 2, 10, and 20 wt.% of complexes; complete data are provided in Table S3. Figure 6: Changes in the percentage of dye decolorization over time for MB (VIS and UV) and CV (UV) with PMMA + (3) composite, as an example. Figure 8 presents the results of the study of changes in the rate constants (h\({}^{-1}\)) for CV solution decolorization under UV light for the tested group of composites (measurement data provided in Figure S6 and Table S5). The decrease in the concentration of both dyes during irradiation follows a linear trend consistent with zero-order kinetics, indicating that the photodecomposition rate of each dye remains constant throughout the measurement period. The analysis of the results indicates that the composites enriched with oxo-Ti(IV) complexes (**1**) and (**2**) exhibited the highest photocatalytic activity under UV light. Among these, the PMMA + (**2**) composites stand out for their exceptional performance, achieving the highest percentage of MB solution decolorization across all tested concentrations (2-20 wt.%), with values ranging from 45.3% to 73.1%, significantly outperforming the PMMA control (17.4%) (Table S4). This superior activity is further corroborated by the decolorization studies on CV solutions, where the PMMA + **(2)** samples with 2-20 wt.% of the complex achieved a decolorization degree between 51.1% and 70.9%, compared to 37.5% for pure PMMA. In contrast, the oxo complex **(3)** and Ru(III) complexes **(4)** and **(5)** showed markedly lower photocatalytic efficiencies. Notably, for all composites, the photocatalytic activity was consistently improved with increasing concentrations of the complexes in the PMMA matrix. However, it should be emphasized that the composites containing Ru(III) complexes did not exhibit any photocatalytic activity at the lowest concentration tested (2 wt.%) in the decolorization of CV solutions (Figures 8 and S6). The studied samples were also irradiated with visible light (Vis) to assess their effect on the decolorization of MB solutions. The results of these measurements are presented in Figure 7 and Figure S7, as well as Table S6. Subsequently, these experiments were repeated over three cycles to verify the stability of the photocatalytic activity of the tested systems. The findings demonstrated that the photocatalytic activity of the studied samples remained consistent across all measured cycles (Figure 9). The results of our investigations revealed that composites containing complexes **(1)** and **(2)** exhibited lower photocatalytic activity under visible light compared to their activity under UV radiation (Figure 7). However, the composite containing complex **(3)** as a filler showed a significant increase in activity under visible light, nearing the activity observed under UV exposure (Figure 7 and Table S6). In contrast, both composites containing Ru(III) complexes (PMMA + **(4)** and PMMA + **(5)**) displayed notable activity under visible light.