# Synthetic Routes to Silsesquioxane-Based Systems as Photoactive Materials and Their Precursors
## 1 Introduction
### Cross-Metathesis and Related Modifications for Silyalkenyl Fragment Formations
Surprisingly, in obtained products, no obvious \(\lambda_{\text{em}}\) peak shift was observed for solid- and solution-state spectra, while the \(\lambda_{\text{ab}}\) of polymer films (solid) was slightly blue-shifted in comparison to those in a solution. These slight shifts were probably due to the aggregation-induced disorder. The authors of the study observed small 4-13 nm red shifts in the PL \(\lambda_{\text{em}}\) for solution compared to the solid state, mainly because of the restriction in conformational motion. It is worth mentioning that \(\lambda_{\text{ab}}\) and \(\lambda_{\text{em}}\) gradually red-shift along with the increase of chain length (i.e., from P1 to P3). It was demonstrated that all the hybrid polymers exhibited a quantum yield higher than 95%, while for the PF it was only 79%. The reason for such high values of P1-P3 quantum yields could be the confinement of excitons within each oligofluorene unit due to the interconnecting DDSQ cage. Thus, the oligofluorene fragments behaved as isolated, not conjugated chromophores. According to the authors, these results suggested that the optical properties of oligofluorenes were faithfully maintained in the proposed final materials. To demonstrate the potential of synthesized materials in organic electronic applications, the authors successfully prepared two OLED devices that maintained color stability and purity when compared to PF. In 2006, [PERSON] et al. demonstrated that a hydrosilylation reaction may be used for the efficient synthesis of POSS-based blue-light electroluminescent (EL) nanoparticles containing perfluorene moieties on each of their eight arms [99]. This material was obtained via the Pt-catalyzed hydrosilylation between commercially available octa(dimethylsiloxy)silesquioxane T\({}_{8}\) (Q\({}_{8}\)M\({}_{8}\)) and an allyl-functionalized terfluorene (Figure 26). The material displayed high thermal stability (\(T_{\text{d}}\)5\({}^{\text{\%}}\) = 379 \({}^{\circ}\)C) and good film-forming properties (tests on a quartz or an indium tin oxide plate). The photophysical analyses were performed in solution (THF) and in solid state. The maximum \(\lambda_{\text{ab}}\) in solution was 352 nm (353 nm in a solid state) with PL emission maxima \(\lambda_{\text{ab}}\) at 394 and 415 nm (401 and 420 nm in a solid state). These results were compared with those for the organic counterpart poly(dihexylfluorene) and were coincided both in solution and in solid state. This good spectral overlap suggests that POSS-FL can be used as a dopant of blue-light-emissive conjugated polymers, such as polyfluorens, to increase their quantum efficiencies through energy transference and the isolation of chromophores, as well as in applications requiring electroluminescent nanoparticles. It is worth mentioning that the external quantum efficiency in EL devices of POSS-derivative doped poly(dihexylfluorene) blends were found to be four to eight times higher than that of their organic analogue. Other examples based on the same procedure for anchoring the chromophore part onto the T\({}_{8}\) core were presented by [PERSON], [PERSON] and [PERSON] group [100]. They used a hydrosilylation process for the synthesis of a series of macromolecular materials composed of an inorganic Q\({}_{8}\)M\({}_{8}\) core and  
Figure 15:1 Synthesis of octakis(terfluorene)silsesquioxane via hydrosilylation. organic fluorescent emitters covalently attached either monochromatically or in a combination of mixed emitters (POSS with different chromophore systems) (Figure 27). Hydrosilylation was performed using [PERSON]'s catalyst with fixed and controlled reagents' stoichiometry; however. the final product yields may be not satisfying and may suggest further optimization of the procedure. Monochromatic POSS-emitter products (1-3) were obtained with a 60%, 47% and 61% yield, respectively, while isolated yields of POSS containing a combination of two different emitters (4-7) were not higher than 26%. All compounds were proved to have higher thermal stability than their organic emitters.