Polyhedral Oligomeric Silsesquioxane (POSS) Chemistry

Polyhedral oligomeric silsesquioxanes (POSS) have long served as more than a hybrid organic-inorganic filler for polymers. Their partially condensed silanol forms present a rigid, oxygen-rich pocket that closely resembles a fragment of amorphous silica, and this pocket is an excellent ligand for metal ions of nearly every part of the periodic table. Single-crystal X-ray diffraction has been the decisive tool for confirming what these metal-POSS assemblies actually look like, since spectroscopic and computational evidence alone can rarely distinguish between competing cage topologies. This review surveys recent crystallographically confirmed metal-POSS complexes, organized by the metal center, and closes with a synthesis of the structural trends that emerge once the diffraction data are compared side by side. POSS as a Ligand Platform for Metal Ions The starting point for nearly every metal-POSS complex discussed below is an incompletely condensed silsesquioxane, most often a tris...

中文版本 / Chinese version: POSS 聚(1-卤代乙炔)：无催化剂固相聚合路线 Polyhedral oligomeric silsesquioxane (POSS) poly(1-haloacetylene) conjugated networks have been synthesized by Marta Cieplucha, Mateusz Janeta, and Sławomir Szafert at the Faculty of Chemistry, University of Wrocław, as reported in Materials Chemistry Frontiers in 2025. Three octa-functionalized monomers, POSS-C2Cl, POSS-C2Br, and POSS-C2I, were prepared by amide coupling of octa(3-aminopropyl)silsesquioxane with the corresponding 4-(haloethynyl)benzoyl chloride and were shown to undergo thermal polymerization in the solid state without any transition metal catalyst, yielding highly cross-linked poly(1-haloacetylene) networks. This work constitutes the first reported polymerization of a 1-iodoethyne derivative and the first example of 1-haloalkyne polymerization achieved entirely in the absence of metal-based initiators. Synthesis of Octa-Functionalized POSS Haloalkyne Monomers Scheme 1. Synthe...

中文版本 / Chinese version: POSS 二氟硼光催化剂：硫醚选择性氧化制亚砜 The publication titled “Polyhedral oligomeric silsesquioxane difluoroboron complexes as cooperative octo-site catalysts for the photooxidation of sulfides to sulfoxides” by Mateusz Janeta and Sławomir Szafert, published in Inorganic Chemistry Frontiers on April 17, 2025, presents a study on the development of novel metal-free photocatalysts. These catalysts are based on polyhedral oligomeric silsesquioxanes (POSS) functionalized with difluoroboron complexes. Scheme 1. Synthesis of POSS-sal-BF 2 , POSS- tert -BF 2 , and POSS-npht-BF 2 . Isolated yields in parentheses. Key Highlights Catalyst design. The researchers synthesized three new difluoroboron-functionalized POSS complexes, namely POSS- tert -BF 2 , POSS-sal-BF 2 , and POSS-npht-BF 2 , derived from imine-functionalized POSS s. Photocatalytic performance. These complexes demonstrated exceptional efficiency in the aerobic photooxidation of sulfides to sulfoxides, significantly ...

中文版本 / Chinese version: POSS 八亚胺倍半硅氧烷：晶体结构与热性能 Four novel octa-imine-functionalized polyhedral oligomeric silsesquioxane (POSS) derivatives, designated POSS-6 through POSS-9 , have been reported by Mateusz Janeta and Sławomir Szafert in the Journal of Molecular Structure in 2025. These compounds were obtained by modular Schiff base condensation of octa(3-aminopropyl)silsesquioxane hydrochloride with the appropriate aromatic aldehyde in isolated yields ranging from 84 to 92 percent without chromatographic purification, and their structures were fully established by single-crystal X-ray diffraction. The identity of the peripheral substituent (hydroxyphenyl, bromophenyl, thiophene, or dibenzofuran) was found to govern both the non-covalent interaction topology in the solid state and the thermal behavior, with T 5% decomposition onset temperatures spanning from 305 to 326 °C across the four derivatives. Synthesis of Octa-Imine POSS Derivatives by Schiff Base Condensation All four compo...