Highly active dinuclear cobalt complexes for solvent-free cycloaddition of CO2 to epoxides at ambient pressure

Dinuclear Co-based catalysts are used for the coupling reaction of epoxides and CO₂ in the presence of a cocatalyst.

The influence of structural isomerism on fluorescence and organic dye selective adsorption in two complexes based on flexible ligands

Based on Cd(NO₃)₂·4H₂O and 4,4'-((5-carboxy-1,3-phenylene)bis(oxy))dibenzoic acid (H₃cpbda), two isomeric coordination polymers, {[Cd_1.5(cpbda)(bpa)(H₂O)₂]·1.5H₂O}_n (1), [Cd(H₂cpbda)₂(bpa)_0.5(H₂O)]_n (2), were synthesized by using different solvent-systems. The complexes were characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction, and thermogravimetric analysis. Owing to the obvious structural difference between the two isomeric complexes, the further fluorescence sensing and dye selection and adsorption were investigated. The 3D tight stacking structure of 1 strengthened the fluorescence emission and the loose 2D layer structure of 2 generated the active selection and adsorption of the Malachite Green Oxalate (MGO) dye.

Catalytic conversion of CO2 into propylene carbonate in a continuous fixed bed reactor by immobilized ionic liquids

In this study, functionalized composite catalysts, namely, ILs (ILX/(ZnBr₂)₂), with functional groups immobilized on a molecular sieve (MCM-22) support were synthesized with the help of a silane coupling agent, 3-chloropropyltriethoxysilane (CPTES).

Recent Developments in the Synthesis of Cyclic Carbonates from Epoxides and CO2

The use of CO₂ as a C1 building block will be of essential importance in the future. In this context the synthesis of cyclic carbonates from epoxides and CO₂ gained great attention recently. These products are valuable compounds in a variety of chemical fields. The development of new catalysts and catalytic systems for this atom-economic, scalable, and industrially relevant reaction is a highly active research field. Over the past 17 years great advances have been made in this area of research. This chapter covers the survey of the important known classes of homogeneous catalysts for the addition of CO₂ to epoxides. Besides pioneering work, recent developments and procedures that allow this transformation under mild reaction conditions (reaction temperatures of ≤100 °C and/or CO₂ pressures of 0.1 MPa) are especially emphasized.

Aluminum-Mediated Formation of Cyclic Carbonates: Benchmarking Catalytic Performance Metrics

We report a comparative study on the activity of a series of fifteen binary catalysts derived from various reported aluminum-based complexes. A benchmarking of their initial rates in the coupling of various terminal and internal epoxides in the presence of three different nucleophilic additives was carried out, providing for the first time a useful comparison of activity metrics in the area of cyclic organic carbonate formation. These investigations provide a useful framework for how to realistically valorize relative reactivities and which features are important when considering the ideal operational window of each binary catalyst system.

Lewis basicity of relevant monoanions in a non-protogenic organic solvent using a zinc(ii) Schiff-base complex as a reference Lewis acid

The Lewis basicity of relevant anions is reported for the first time and compared with that of neutral bases.

On the Lewis acidic character of bis(salicylaldiminato)zinc(ii) Schiff-base complexes: a computational and experimental investigation on a series of compounds varying the bridging diimine

The electronic effects induced by the geometry of the 1,2-diimine bridge control the Lewis acidic character in a series of Zn^II Shiff-base complexes.

Aluminum complexes derived from a hexadentate salen-type Schiff base: synthesis, structure, and catalysis for cyclic carbonate synthesis

The unexpected aluminum complex was synthesized and found to be active in the cycloaddition reaction of terminal epoxides and CO₂ at atmospheric pressure.

Cavitand-Based Polyphenols as Highly Reactive Organocatalysts for the Coupling of Carbon Dioxide and Oxiranes

A variety of cavitand-based polyphenols was prepared from cheap and accessible aldehyde and resorcinol/pyrogallol reagents to give the respective resorcin[4]- or pyrogallol[4]arenes. The preorganization of the phenolic units allows intra- and intermolecular hydrogen bond (HB) networks that affect both the reactivity and stability of these HB-donor catalysts. Unexpectedly, we found that the resorcin[4]arenes show cooperative catalysis behavior compared to the parent resorcinol in the catalytic coupling of epoxides and CO2 with a significantly higher turnover. At elevated reaction temperatures, the resorcin[4]arene-based catalyst 3 d displays the best catalytic performance with very high turnover numbers and frequencies, combining increased reactivity and stability compared to pyrogallol, and an ample substrate scope. This type of polyphenol structure thus illustrates the importance of a new, highly competitive organocatalyst design to devise sustainable CO2 conversion processes.

Fabrication of innovative ZnO nanoflowers showing drastic biological activity

The present article highlights a facile approach towards the synthesis of ZnO nanoflowers using designed single molecular precursors (1 and 2) at room temperature. The relative biological activities of 1, 2 and ZnO nanoflowers have also been demonstrated.

Synthesis and characterization of 1,3-diamino-graphene as a heterogeneous ligand for a CuI-catalyzed C–N coupling reaction

1,3-Diamino-graphene was synthesized and used as an efficient heterogeneous ligand for a CuI-catalyzed C–N coupling reaction.

Metal complexes bearing 2-(imidazol-2-yl)phenol ligands: synthesis, characterization and catalytic performance in the fixation of carbon dioxide with epoxides

A series of metal complexes bearing 2-(imidazol-2-yl)phenol ligands were synthesized and proven to be efficient catalysts for the fixation of CO₂.

Zn(ii) assisted synthesis of porous salen as an efficient heterogeneous scaffold for capture and conversion of CO2

A new zinc-salen functionalized porous polymer has been synthesized by an easy one-step process, which shows unprecedented catalytic efficiency in the CO₂ fixation reaction via cycloaddition of CO₂ with epoxides.

New ionic cobalt(iii) complexes based on the N,N-bis(2-pyrazinecarboxamide)-1,2-benzene ligand: application to the formation of organic carbonates from epoxides and CO2

New cobalt(iii) complexes based onN,N-bis(2-pyrazine-carboxamide)-1,2-benzene were tested as catalysts for the coupling of propylene- and cyclohexene oxide with CO₂.