Synthesis and Steady State Photophysical Property Analysis of Beads on a Chain (BoC) Silsesquioxane Oligomers Containing Arene and Heteroarene Cross-linkers

Silsesquioxane-based materials are garnering considerable attention due to their unique structural and electronic properties which enable use in diverse fields of study. In this article, we investigate a series of hybrid oligomeric materials comprising a silsesquioxane (SQ) backbone linked by conjugated organic cross-linkers and assess their photophysical properties in the steady state absorption and emission realms. Silsesquioxanes improve the thermal and photo stabilities of the organic components, offer enhancements in the molar extinction coefficients of absorption, and have a significant influence on their emission properties. We used Heck cross-coupling reactions to build oligomers with a vinyl/phenylSQ cage backbone linked with a series of different cross-linkers including 2,7-dibromo-9-fluorenone, 2,7-dibromo-9,9-dimethylfluorene, 1,4-dibromo-2,5-dimethoxybenzene, 2,5-dibromopyridine, 2,6-dibromopyridine, 2,3-dibromothiophene, 2,5-dibromothiophene, and 2,5- dibromothieno [3,2-b]thiophene. Each of these linkers showed reasonable conversion to oligomers and exhibited a wide array of fluorescence quantum yield and shifts in the absorption and emission spectra dependent on the variations in substitution position. We confined the study to explore the overall steady state spectral properties of these synthesized hybrid materials in their solution phases. Understanding the basic photophysical processes in these materials will pave the way towards their use in photovoltaic or electroluminescence applications.

Automated summary

This article investigates a series of silsesquioxane-based materials with unique structural and electronic properties, assessing their photophysical characteristics. By improving thermal and photo stability, enhancing molar extinction coefficients of absorption, and influencing emission properties through the use of different cross-linkers, these materials show promise for applications in photovoltaic or electroluminescence fields.