# Synthetic Routes to Silsesquioxane-Based Systems as Photoactive Materials and Their Precursors
## 1 Introduction
### Cross-Metathesis and Related Modifications for Silyalkenyl Fragment Formations
The authors also demonstrate the obtained material's potential application in organic electronic diodes. They fabricated an electroluminescent device that showed a maximum brightness of 320 cd m\({}^{-2}\) at 20 V drive voltage with 40 mA cm\({}^{-2}\) current density. This proved that DDSQ are promising compounds useful for OLEDs. [PERSON] and [PERSON]'s groups reported on dihydro-substituted double-decker silsesquioxane (DDSQ-2 SiH) efficient modification using [PERSON]'s mediated hydrosilylation reaction protocol with precise reaction time control (FTIR in situ). This facilitated selective formation of a series of molecular as well as macromolecular DDSQ-based systems with ethyl-bridged \(\pi\)-conjugated arenes (Figure 24) [92]. Obtained compounds were verified in terms of their thermal stability (higher than organic couterparts) as well as their photophysics. A UV-vis analysis of the resultng molecular and macromolecular compounds in comparison to the respective arenes was performed. For the DDSQ-based products, the absorption spectra combined the shape of the DDSQ unit as well as the organic counterpart. For the 1-(4-vinylphenyl)naphthalene derivative, the absorption spectrum showed a 21 nm blue-shifted torn peak at \(\lambda_{\rm ab}\) = 257 and 330 nm, which was different than the basic arene (\(\lambda_{\rm ab}\) = 278 nm). This result may suggest the involvement of Si-O-Si core in the excited state, as has already been reported by [PERSON] and [PERSON] for mono- and octa-functionalized silsesquioxanes [47; 58]. The photophysical and thermal features could enable the application of these compounds in OLEDs devices. Our group studied the hydrosilylation of olefins and alkynes with silsesquioxanes with one, four and eight reactive Si-H moieties, which constitute a valuable group of precursors used in the formation of photoactive materials [93; 94; 95; 96; 97]. In 2014 [PERSON], [PERSON] and [PERSON] demonstrated a practical route to the synthesis of a series of three hybrid polymers containing a periodically interconnected DDSQ unit and oligofluorenes in the main chain [98]. Hydrosilylation was employed to prepare these materials by sequential addition of dihydro-substituted DDSQ (DDSQ-2 SiH) and fluoresnes: monomer (\(n\) = 1), dimer (\(n\) = 2) and trimer (\(n\) = 3) in the presence of the [PERSON]'s catalyst (Figure 25). The obtained copolymers (P1-P3) had molecular weights of \(M_{n}\) = 9700, (Polydispersity Index) PDI = 2.55; \(M_{n}\) = 18,700, PDI = 1.45; and \(M_{n}\) = 39,300, PDI = 1.34, respectively, and were soluble in common organic solvent. TG analyses indicated a high level of thermal resistance in the obtained systems, up to 446 \({}^{\circ}\)C. This means that the block copolymer containing DDSQ units displayed an  
Figure 24: General procedure for the synthesis of molecular and macromolecular aryl-ethyl-double-decker-shaped silsesquioxanes via hydrosilylation. Figure 15:0 Synthesis of oligomers with the DDSQ unit and oligofluorenes in the main chain via hydrosilylation. improvement in their thermal stability when compared to neat poly(fluorene) (PF, 417 \({}^{\circ}\)C). The authors also demonstrated that the thermal stability of these products was affected by the ratio of DDSQ in the polymer chain, since the DDSQ can lower thermal conductivity and work as a thermal barrier to isolate heat. All polymers were thermoplastic, with significantly higher \(T_{\text{g}}\) (up to 125 \({}^{\circ}\)C) than the corresponding PF (\(T_{\text{g}}\) = 55 \({}^{\circ}\)C). The optical properties of the hybrid nanocomposites were determined and compared with the chromophores used. The absorption and emission spectra (in solution and solid) were different. According to the literature, conjugated polymers exhibited significant changes in their solid-state spectra because of interchain interaction (e.g., for PF, \(\lambda_{\text{em}}\) changed from 459 to 539 nm in the solid state).