Investigating the role of SBA-15 silica on the activity of quaternary ammonium halides in the coupling of epoxides and CO2

CO2 fixation: cycloaddition of CO2 to epoxides using practical metal-free recyclable catalysts

The conversion of CO2 into valuable chemicals is a crucial field of research. Cyclic organic carbonates have attracted great interest because they can be prepared under mild conditions and because of their structural versatility which enables a large variety of applications. Therefore, there is a need for potent and yet practical catalysts for the cycloaddition of CO2 to cyclic carbonates that are able to combine availability, low cost and an adequate performance. We review here several recyclable catalytic systems that are readily available, easy to prepare, and inexpensive with an eye to the future development of more efficient practical catalysts through the provided guidelines.

Catalytic Strategies for the Cycloaddition of CO2 to Epoxides in Aqueous Media to Enhance the Activity and Recyclability of Molecular Organocatalysts

The cycloaddition of CO2 to epoxides to afford versatile and useful cyclic carbonate compounds is a highly investigated method for the nonreductive upcycling of CO2. One of the main focuses of the current research in this area is the discovery of readily available, sustainable, and inexpensive catalysts, and of catalytic methodologies that allow their seamless solvent-free recycling. Water, often regarded as an undesirable pollutant in the cycloaddition process, is progressively emerging as a helpful reaction component. On the one hand, it serves as an inexpensive hydrogen bond donor (HBD) to enhance the performance of ionic compounds; on the other hand, aqueous media allow the development of diverse catalytic protocols that can boost catalytic performance or ease the recycling of molecular catalysts. An overview of the advances in the use of aqueous and biphasic aqueous systems for the cycloaddition of CO2 to epoxides is provided in this work along with recommendations for possible future developments.

Structure-Property Relationship for Different Mesoporous Silica Nanoparticles and its Drug Delivery Applications: A Review

Mesoporous silica nanoparticles (MSNs) are widely used as a promising candidate for drug delivery applications due to silica’s favorable biocompatibility, thermal stability, and chemical properties. Silica’s unique mesoporous structure allows for effective drug loading and controlled release at the target site. In this review, we have discussed various methods of MSNs’ mechanism, properties, and its drug delivery applications. As a result, we came to the conclusion that more in vivo biocompatibility studies, toxicity studies, bio-distribution studies and clinical research are essential for MSN advancement.

Simple carbonaceous-material-loaded mesoporous SiO2 composite catalyst for epoxide-CO2 cycloaddition reaction

In this paper, a novel arginine-glucose derived carbonaceous-material-loaded SiO₂ composite catalyst (Ar-G-CM/SiO₂) was synthesized from non-toxic and harmless reagents (arginine, glucose and tetraethylorthosilicate) by simple hydrothermal process. Mesoporous SiO₂ with high specific area served as support for carbonaceous material and provided extra hydrogen bond donor (HBD) groups. Ar-G-CM/SiO₂ with acid-base dual functional groups (COOH, NH₂) and HBD group (OH) presented 62% yield and 99% selectivity to product of propylene carbonate in CO₂ cycloaddition reaction with propylene oxide even at 40 °C, 2 MPa under metal-absent and solvent-free conditions. For some less active epoxides with steric hindrance, Ar-G-CM/SiO₂ also showed good yield and selectivity over 90% by raising temperature to 120 °C. Furthermore, the Ar-G-CM/SiO₂ catalyst could be reused for six successive cycles without significant decrease in catalytic activity or structural deterioration, because the carbon deposition was restrained owing to the mesoporous structure of the catalyst.

B-Doped and NH2-functionalized SBA-15 with hydrogen bond donor groups for effective catalysis of CO2 cycloaddition to epoxides

The novel B-SBA-15-NH₂ catalyst with Lewis acid–base properties and hydrogen bond donor groups exhibited good catalytic performance for CO₂ conversion under metal- and solvent-free conditions.