# Synthetic Routes to Silsesquioxane-Based Systems as Photoactive Materials and Their Precursors
## 1 Introduction
### Cross-Metathesis and Related Modifications for Silyalkenyl Fragment Formations
As a result, octa(Br-styrene)T\({}_{8}\) was applied as a reagent in efficient Heck coupling with four types of carbonyl-substituted vinylstyrene, producing a good isolation yield of 1-4 products (43-65%). The importance of this research lies in the combination of carboranes known from their 3D electron delocalization and the fact that they were additionally coupled with \(\pi\)-conjugated arene fragments along with the T\({}_{8}\) silsesquisoxane unit, enhancing thermal stability and also affecting the electronic properties of these systems. All compounds were characterized in terms of their absorption-emission properties (analysis performed in DCM) and supported by DFT calculations. The absorption spectra shapes were similar with \(\lambda_{\text{ab}}\) near 338 nm and all emission maxima wavelengths red-shifted to \(\sim\)392 nm (\(\lambda_{\text{ex}}\) = 340 nm). Interestingly, the highest symmetry of product 1 in comparison with products 2-4 (Figure 19) was visible in the broadening of fluorescence in the red part of the spectra that indicates intermolecular interactions of the o- and m-substituted carborane units. This also caused the fluorescence quantum yield to be the highest for 1 (\(\sim\)60%). Additionally, the emission spectra of drop-casted films revealed its strong bathochromic effect (\(\lambda_{\text{em}}\) 450-484 nm) due to the aggregation and intermolecular interactions of substituents. However, these systems exhibited remarkable thermal resistance, with up to 87% residue on the initial weight at 1000 \({}^{\circ}\)C, making them excellent candidates for luminescent materials. Figure 18: Reaction path for the selective sequence of cross-metathesis and Heck coupling towards (E)-styrenyl-substituted T\({}_{8}\), T\({}_{10}\) and T\({}_{12}\). Metallative Coupling (Si, Ge) as a Complementary Catalytic Reaction towards the Formation of Alkenylsilyl Moieties  
The importance of catalytic transformations in the chemistry of organosilicon compounds is undeniable, and the reactivity of the transition metal-p block element (TM-E) bond often determines the kinetics and selectivity (region- and stereo-) of these processes. This aspect also concerns silsesquioxanes. A class of catalytic processes attractive in the organosilicon chemistry is silylative coupling (trans-silylation), discovered and developed by the [PERSON] group over 20 years ago. This is a process between vinylisanes and olefins, involving the activation of the =C-H bond at the \(\alpha\) and \(\beta\) carbon atom of the vinyl group and the C\({}_{vinyl}\)-Si bond in the vinylsilane molecule, with simultaneous elimination of the ethylene molecule catalyzed by TM-H/Si (TM = Ru, Ir, Rh, etc.) complexes (the insertion-elimination mechanism that we proved) [79; 80; 81; 82]. This leads to unsaturated \(E\)/\(Z\) and \(gem\)-alkenylsilanes. Because the selectivity of this reaction is strictly controlled, it results in a selective formation of \(E\)-isomers depending on the reaction conditions and catalytic system. The silylative coupling may be considered a complementary process to the abovementioned cross-metathesis. Despite the fact that these two reactions proceed via different mechanisms and catalytic systems, they result (when optimized) in the selective formation of \(E\)-1,2-substituted silylalkenes (in contrast to silylative coupling, which may be regoselective towards isomeric 1,1-substituted alkenes). In the chemistry of vinyl-substituted silsesquioxane modifications using both reactions, silylative coupling, metathesis and also hydrosilylation, our team gained a vast experience. In the scope of this research, it was shown that the studied processes could be used for the synthesis of unsaturated silsesquioxane-based systems using mono- and octavinyl silsesquioxanes (T\({}_{8}\)) as well as divinyl-substituted DDSQ reagents.