# Synthetic Routes to Silsesquioxane-Based Systems as Photoactive Materials and Their Precursors
## 1 Introduction
### Cross-Metathesis and Related Modifications for Silyalkenyl Fragment Formations
reported on the efficient formation of silsesquioxane-based phosphorescent materials consisting of an emissive Ir(III) complex and carbazole moieties (Figure 34) [114; 115]. These systems were based on 3-(pyridin-2-yl)coumarinato N,C4 as ancillary ligand and varied the additional ligand that was used to bind the POSS core with allyl group (i.e., 8-hydroxyquinolinolate and acetylacetone derivatives). The authors obtained compounds with one and two Ir moieties anchored to one POSS molecule with 12.5%, 23% and 55% yields, respectively. Their enhanced thermal stability was proven. The photoluminescence spectra of the POSS systems (in DCM and solid state) were obtained. Again, the absorption spectra were derived from carbazole units (\(\lambda_{\mathrm{ab}}=360\) nm) as well as spin-allowed and spin-forbidden metal-to-ligand charge transfers (MLCT) (\(\lambda_{\mathrm{ab}}=400\) nm). The emissions of these  
Figure 15:9 The POSS-based complexes of Ir and Pt obtained by hydrosilylation. systems were similar and revealed the presence a weak green emission at \(\lambda_{\rm em}\) = 535 nm, along with a dominant red emission at \(\lambda_{\rm em}\) = 635 nm for 8-hydroxyquininolinolate, a strong green emission at \(\lambda_{\rm em}\) = 530 nm and a dominant green emission \(\lambda_{\rm em}\) = 567 nm. The quenching of the emission within the concentration rise was diminished due to the separation of the chromophores onto the POSS core. These compounds were also successfully applied to the fabrication of electroluminescence devices exhibiting high brightness and higher external quantum efficiencies. In 2016, [PERSON] and [PERSON] reported on a synthesis of POSS-based systems containing one, two and three moieties of Ir(III) complex that were also based on 3-(pyridin-2-yl)coumarinato N,C [4]) as an ancillary ligand, and allyl acetylacetone modified with n-Bu-carbazole molecule (Figure 35) [116]. These systems were obtained using the abovementioned general synthetic approach via hydrosilylation, with 26.4%, 14.7% and 6.4% yields, respectively, that may suggest the optimization of reaction conditions for better yields. Obtained compounds were verified in terms of their thermal resistance, which was proven. The absorption and emission spectra were, in general, analogous to the previously reported ones (i.e., absorption derived from the carbazole unit and spin-allowed and -forbidden metal-to-ligand charge-transfer (MLCT) transitions). The emission (\(\lambda_{\rm ex}\) = 430 nm) spectra resembled each other and exhibited mainly green emission at \(\lambda_{\rm em}\) = 530 nm and minor green-yellow at \(\lambda_{\rm em}\) = 570 nm. The results also present a reduction of quenching from Ir-complex moiety interactions due to a bulky POSS core. The electroluminescent device fabricated using the abovementioned compounds revealed an enhanced quantum efficiency that proved its application utility. Other Catalytic Reactions leading to the Formation of POSS-Based Systems of Interesting Photophysical Properties  
A group of catalytic processes known as \"click reactions\" has gained a profound interest in (bio-) organic chemistry and also materials chemistry, a term that was successfully introduced into literature by [PERSON] in 2001 [117]. In general, these are perceived as mainly one-pot, modular processes, with a wide tolerance to other functional groups that generate minimal and inoffensive byproducts. They are supposed to be stereospecific and are characterized by a high thermodynamic driving force to favor a single product formation with a high yield. Additionally, the process would preferably have mild and simple reaction conditions, along with commercially available reagents to obtain products easily  
Figure 17:0 The Ir complexes of spherosilicate obtained through hydrosilylation. Figure 17:1 The spherosilicate-based complexes with one, two and three Ir complexes obtained by hydrosilylation. isolated, mainly via crystallization or distillation.