# Synthetic Routes to Silsesquioxane-Based Systems as Photoactive Materials and Their Precursors
## 1 Introduction
### Cross-Metathesis and Related Modifications for Silyalkenyl Fragment Formations
The most interesting part of the research was disclosed in defining the photophysical properties of obtained compounds. Solution and thin-film photoluminescence spectra were measured and compared for both the free emitters and the modified POSS. It was demonstrated that monochromatic products (1-3) have similar absorbance and emission spectra to their free emitter counterparts both in solution and in a solid state. Thus, using POSS core as a scaffold does not influence the color of the emitters applied. Surprising results were obtained for products bearing more than one type of emitter (4-7). It was found that lower-energy emissions (orange or yellow) dominated in the photoluminescence spectrum for materials 4-7 due to a strong intramolecular energy transference from the neighboring higher-energy blue emitter on the POSS. This high degree of energy transference derives from two major factors: the overlapping of the blue emitter's emission band with its lower-energy absorption band, and the blue and orange emitters' short intramolecular distance. Overall, the authors indicated that these materials were easily processable and could be spin-coated from solution for the fabrication of OLED devices. They were also prepared and tested with dopants of selected POSS-based systems. In 2009, [PERSON] et al. described the synthesis of a similar type of material, i.e., POSS-based electroluminescent nanoparticles, containing anthracenenaphthyl fragments at each of their eight arms [101]. The procedure involves the hydrosilylation of Q8M8 with vinyl-functionalized 9-naphtalene-2-yl-10-phenyl anthracene in the presence of 2 mol % of [PERSON]'s catalyst (Figure 28). Figure 15:2 Synthesis of octa(anthracenenaphthyl)silesquisoxane T8 via hydrosilylation. Figure 15:3 Synthetic hydrosilylation route to T8-based systems with mixed organic fluorescent emitters. POSS-NPA was analyzed to investigate its thermal and photophysical properties. It was found to be thermally stable up 450 \({}^{\circ}\)C, with high \(T_{\rm g}\) = 154 \({}^{\circ}\)C. The UV-vis absorption and PL emission maxima of the final product in solution (chlorobenzene) were found to be 378 and 433 nm, while those characteristics for the product in a solid state were 379 and 464 nm, respectively. These results indicate the aggregation of POSS-NPA molecules and their intermolecular interactions. The authors fabricated an electroluminescent (EL) device that shows blue light emissions. [PERSON] and [PERSON] reported on the synthesis of a new star-type POSS-based molecular hybrid containing stilbene chromophore [102]. These materials were prepared by the hydrosilylation of a series of alkynylstilbenes with octahydridosilesquioxane (OHS) (Figure 29). The reaction was performed in refluxing 1,2-dichloroethane (DCE) in the presence of platinum dicyclopentadiene complex [Pt(dcp)], and led to the formation of expected products with isolated yields ranging from 42 to 51%. However, this catalyst seems to have lower selectivity, as in all cases the formation of \(\alpha\) and \(\beta\) isomer mixture was detected (\(\alpha\):\(\beta\) = 39-43:57-61). All products exhibited high thermal stability (\(T_{\rm d}\)\({}^{5\%}\) up to 320 \({}^{\circ}\)C, \(T_{\rm g}\) up to 250 \({}^{\circ}\)C). The THF solutions of the products were easily cast into films, whereas films of the chromophore could not be obtained in the same conditions. The photophysics were verified and the UV-is spectra (in THF) revealed the presence of strong absorption peaks at \(\lambda_{\rm ab}\) = 336 (H1), 339 (H2), 335 (H3) and 360 (H4) nm. It was also found that alkoxy chain length exerts little influence on the absorption of products H1-3. In the case of H4 the absorption peak was red-shifted, which may be attributable to a stronger intramolecular interaction and formation of the excited state.