Polyhedral Oligomeric Silsesquioxane

  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— POSS-tert-BF₂ , POSS-sal-BF₂ , and POSS-npht-BF₂ —derived from imine-functionalized POSSs. Photocatalytic Performance:  These complexes demonstrated exceptional efficiency in the aerobic photooxidation of sulfides to sulfoxides, signific...

  A novel amphiphilic azo-functionalized polyhedral oligomeric silsesquioxane (azo-POSS) developed by an international team of chemists demonstrates high selectivity and efficiency in the removal of cationic dyes from aqueous solutions, with potential for light-controlled phase transfer. Addressing an Urgent Environmental Challenge The contamination of water sources with synthetic dyes, particularly from textile and industrial effluents, poses a serious threat to ecosystems and human health. These dyes are often toxic, persistent, and resistant to conventional treatment methods. As such, the development of advanced materials for selective and efficient dye removal has become a pressing research focus in environmental chemistry. Azo-POSS: A Smart, Amphiphilic Phase Transfer Agent In 2024 publication in ChemPlusChem , authors present the synthesis and functional evaluation of azo-POSS , a molecule designed to bridge the hydrophilic and hydrophobic domains with the added advant...

  The Problem: Colorful Water, Toxic Consequences Ever wonder what happens to the vivid blues, purples, and reds used in textiles, paper, and plastic after they’ve served their purpose? Many of these dyes end up in water systems—and they don’t just look bad. Some are toxic, persistent, and hard to remove , linked to health issues like allergies, skin irritation, and even cancer. Traditional cleanup methods (like filtration or chemical treatments) are often inefficient, costly, or non-selective . So, scientists are racing to build smarter, more targeted tools for water purification. The Solution: A Smart Sponge Called Azo-POSS Enter: azo-POSS , a molecule engineered by researchers led by Eftekhari-Sis and Janeta. It’s a hybrid nanomaterial , with a structure inspired by nature and tweaked by chemistry: 🧊 A hydrophilic "head" (meaning it loves water) 🔥 A hydrophobic "tail" (it avoids water, prefers oil) 🌗 A light-sensitive "linker" (an az...

  By J.F. Brown, L.H. Vogt, and P.I. Prescott (J. Am. Chem. Soc. 1964, 86, 1120–1125) Adapted. Since the 1870s, chemists have known that treating phenylsilanetriol condensation products with alkali produces soluble compounds with the empirical formula (C₆H₅SiO₁.₅)ₓ. These materials—variously called phenylsilsesquioxanes, phenyl-T resins, or silicobenzoic anhydride—were initially developed in the pursuit of silicon analogs of carboxylic acids. However, despite over half a century of study, the molecular constitution of these compounds remained elusive—until a deeper dive into their equilibrium chemistry began to unlock their secrets. From Clarity to Complexity: Isolating Individual Species The first crystalline phenylsilsesquioxane, initially misidentified as phenyl-T₆ (a tetracyclic hexamer), was later corrected to be phenyl-T₈, a pentacyclic octamer. Its isolation was simple—just allow a hydrolysate of phenyltrichlorosilane to stand in the presence of KOH, ethanol, ether, and benz...

  In an era where environmental monitoring and rapid detection of industrial pollutants are more critical than ever, the development of advanced chemical sensors is at the forefront of materials science. A recent study published in Organometallics by Siripanich et al. (2022) introduces an innovative class of dual-response fluorescent sensors based on pyrene-functionalized silsesquioxane (SQ) cages, capable of selectively detecting fluoride ions and polycyclic aromatic hydrocarbons (PAHs) with high sensitivity and speed. Silsesquioxane: A Molecular Scaffold with Multifunctionality Silsesquioxanes (SQs) are cage-like organosilicon compounds with the empirical formula RSiO₁.₅, representing a unique hybrid of inorganic and organic chemistry. Their well-defined structure, solution-processability, and tunable surface chemistry make them excellent candidates for sensor development. The authors synthesized two distinct sensor architectures: Mono-pyrene SQ (Compound 2): A single pyr...

Octavinyloctasilsesquioxane was first prepared in 1978 with a yield of <10% by K. Andrianov 1  and co-workers in the trichlorovinylsilane hydrolysis reaction. Since then, many groups have tried to improve the method of obtaining it. 2-4  In 1997, P. Harrison and Ch. Hall, when examining the hydrolysis of CH 2 =CHSiCl 3  in ethanol, they obtained (CH 2 =CHSiO 1.5 ) 8  with an efficiency of 30%. 5  The use of an ion exchange resin as a catalyst for the hydrolysis and condensation of CH 2 =CHSiCl 3  contributed to an increase in the reaction efficiency to 40%. 6  Compound (CH 2 =CHSiO 1.5 ) 8  was obtained with a yield of 80% using CH 2 =CHSi(OEt) 3  during hydrolysis and tetramethylammonium hydroxide as a phase transfer reagent. 7 Octavinyloctaasilsesquioxane derivatives can be obtained as a result of typical alkene reactions, such as: thiolation, phosphination, hydrosilylation, epoxidation, as shown in scheme below. Thiolation with reagents...

There is little information available in the literature concerning pure, isolated larger cages like the aforementioned heptahedral T 10 . A small amount of T 10  type POSS is usually formed as a by-product during the preparation of T 8  type silsesquioxanes. For example, during the preparation of T 8 H 8  by the hydrolytic condensation of HSiCl 3 , a small amount of T 10 H 10 . 1  is formed in addition to the main product. The formation of more thermodynamically unstable POSS of the T 10  or even T 12  type occurs primarily as a result of the reorganization of the core of the T 8  cage. The transformation of the T 8  cage into a larger one has been published by several research groups. 2–4  For example, V. Ervithayasuporn observed the reorganization of octakis (3-chloropropyl) octasilsesquioxane by reaction with sodium methacrylate, 5  sodium phenoxides, 6  or potassium phthalimide. 7  These reactions resulted in the form...

Octa(3-aminopropyl)silsesquioxane hydrochloride (OAS) was first described in a patent from Wacker-Chemie GmbH. 1  However, this document does not describe the method of its preparation, nor the spectroscopic data allowing its full identification. 2  Seven years late F. Feher 3  investigated the hydrolytic condensation of (3-aminopropyl) triethoxysilane in a methanolic solution using hydrochloric acid as a catalyst to obtain octakis (3-aminopropyl) octasilsesquioxane chloride salt. The yield of the reaction under these conditions is 30%, and the duration is 4 weeks. Modifications to this procedure can be found in the literature based on the change of the hydrolysable group to the methoxy group or the addition of PtCl 4  cocatalyst. However, these treatments do not significantly increase the yield of the reaction. 4–6  Kaneko and co-workers achieved another valuable approach. 7  They investigated the hydrolytic condensation of APTMS using a number of differen...

Quantum-mechanical calculations of octhydrooctasilsesquioxane showed that the highest occupied molecular orbital (HOMO) of this compound consists of atomic orbitals of free electron pairs of oxygen atoms, while the lowest energetically unfilled molecular orbital (LUMO) The lowest unoccupied molecular orbital) is spherical and is located in the center of the silsesquioxane core as shown in figure belowe. The calculations also showed that the energy gap between the HOMO and LUMO orbitals is approximately 6-7 eV. This value is higher than the limit for conductivity (3 eV), which proves that the silsesquioxane core is an insulator. Figure of molecular orbitals: (a) HOMO and (b) LUMO octhydrocarbonoctasilsesquioxane Taking into account the low electronegativity of silicon atoms (1.90 compared with 2.55 for the carbon atom according to the Pauling scale), it can be assumed that the POSS core will behave like an electron donor group. However, experimental studies have shown that the silses...

There are many synthetic methods for the preparation of POSS, other than the methods used in the first attempts to synthesize this type of compounds. These methods can be divided into three categories. The first is the hydrolysis and condensation of silanes, the second is the preparation of a polyhedron compound from silanols containing less than eight silicon atoms, the third is the modification of the side arms of the already existing polyhedric silsesquioxane or the substitution of a hydrogen atom in octahydrooctasilsesquioxane. Synthesis of POSS Compounds   Synthesis of POSS Compounds

Polyhedral Silsesquioxanes Research on compounds containing the Si–O bond has for years been dominated by silicon dioxide, minerals containing repeating SiO₂ fragments, and silicones composed of repeating R₂SiO units (R = alkyl or phenyl). Over the past 20–30 years, there has been a noticeable increase in studies on silsesquioxanes containing the RSiO₁.₅ unit. These compounds, due to the presence of both an inorganic fragment and an organic group, possess hybrid properties. The inorganic Si–O–Si fragment imparts chemical and thermal resistance to these compounds, while the organic R group increases their solubility and provides appropriate reactivity. A wide range of polymeric structures with the general formula (RSiO₁.₅)ₙ can be synthesized, but the most interesting are those with polyhedral architectures.⁴ Polyhedral oligomeric silsesquioxanes (POSS) are three-dimensional organosilicon compounds with the general empirical formula (RSiO₁.₅)ₙ (where R = H, alkyl, alkenyl, or aryl; n =...