Molecular‐Scale Geometric Control of Organosiloxane Cage Frameworks Via Rigid Organic Bridges

ABSTRACT

Organosiloxanes represent a significant class of materials with a wide range of applications; however, achieving molecular‐level framework control remains a fundamental challenge, mainly due to the intrinsic flexibility of the Si–O–Si bond angle. This study demonstrates a strategy to direct discrete cage‐type organosiloxane framework geometries by utilizing rigid phenylene bridges with predefined angles between the Si–C bonds. Hydrolysis and condensation of 1,3‐bis(triethoxysilyl)benzene in the presence of tetramethylammonium hydroxide facilitate the formation of cage‐type organosiloxane trimers and tetramers possessing vertex SiO ⁻ /SiOH groups. Single‐crystal X‐ray analysis of the tetramer stabilized via trimethylsilylation reveals a unique architecture: two tetrasiloxane rings connected by four phenylene bridges in a non‐stacked configuration. Utilizing 1,4‐bis(triethoxysilyl)benzene alters the fixed Si–Ph–Si bond angle, resulting in the selective formation of a cage‐type hexamer. This strategy provides new insights into the molecular‐level control of organosiloxane frameworks for the synthesis of novel nanobuilding blocks and will establish a versatile platform for the design of functional siloxane‐based materials.