Direct and Linker-Exchange Alcohol-Assisted Hydrothermal Synthesis of Imide-Linked Covalent Organic Frameworks

Abstract

Covalent organic frameworks (COFs) are an extensively studied class of porous materials, which distinguish themselves from other porous polymers in their crystallinity and high degree of modularity, enabling a wide range of applications. However, the established synthetic protocols for the synthesis of stable and crystalline COFs, such as imide-linked COFs, often requires the use of high boiling solvents and toxic catalysts, making their synthesis expensive and environmentally harmful. Herein, we report a new environmentally friendly strategyan alcohol-assisted hydrothermal polymerization approach (aaHTP) for the synthesis of a wide range of crystalline and porous imide-linked COFs. This method allows us to gain access to new COFs and to avoid toxic solvents by up to 90% through substituting commonly used organic solvent mixtures with water and small amounts of n-alcohols without being restricted to water-soluble linker molecules. Additionally, we use the aaHTP to demonstrate an eco-friendly COF-to-COF transformation of an imine-linked COF into a novel imide-linked COF via linkage replacement, inaccessible using published reaction conditions.

Recent trends in covalent organic frameworks (COFs) for carbon dioxide reduction

“…75 In this work, they developed crystalline and porous COFs via the ionothermal process in ZnCl 2 and eutectic salt mixtures and this method diminished the reaction time surprisingly compared to that of typical solvothermal process and occurred without using any environmentally harmful solvents or catalyst.Recently,Maschitaet al prepared a series of stable, long-range crystalline porous imide-linked Covalent organic frameworks (TAPA-PMDA-COF, TAPB PMDA-COF and TAPE-PMDA-COF) following a green environmentally friendlyapproach using alcohol-supported hydrothermal polymerization method Please do not adjust margins Please do not adjust margins (aaHTP)permitted to gain a new class of imide-based COFs by avoiding the toxic solvents. 76 Synthesis of imide-linked TAPA-PMDA-COF, TAPB PMDA-COF and TAPE-PMDA-COFoccurred by transformation from imine-linked COFs via linkage substitution.Additionally, Kim's group successfully synthesized a porous crystalline polyimide-linked COFs (PICs) via geomimetic hydrothermal reaction conditions. They also established that the PICs possessed exceptional redox-active properties along with high surface area and servedas a promising anode material in Li-ion batteries.…”

“…Recently, Maschita et al prepared a series of stable, long-range crystalline porous imide-linked covalent organic frameworks (TAPA-PMDA-COF, TAPB PMDA-COF, and TAPE-PMDA-COF) following a green environmentally friendly approach using alcohol-supported hydrothermal polymerization method (aaHTP) permitted to obtain a new class of imide-based COFs by avoiding the toxic solvents. 76 Synthesis of imide-linked TAPA-PMDA-COF, TAPB PMDA-COF, and TAPE-PMDA-COF was formed by the transformation of imine-linked COFs via linkage substitution. Additionally, Kim's group successfully synthesized porous crystalline polyimide-linked COFs (PICs) via geomimetic hydrothermal reaction conditions.…”

Electrochemical (Bio)Sensors Based on Covalent Organic Frameworks (COFs)

“…Another distinctive characteristic of COFs is their inherent porosity [35][36][37]. On the one hand, the overlap of the 2D-COFs layers can build up a three-dimensional structure, traversed by unidirectional cavities also known as pores, which can mainly present as two isomers.…”

Synthesis of Covalent Organic Frameworks (COFs)-Nanocellulose Composite and Its Thermal Degradation Studied by TGA/FTIR

“…Therefore, Abdul et al [ 22 ] developed a strategy of in-situ solid phase doping of carbon nanofibers (CNFs) to prepare COF-CNF hybrid films by mechanochemical methods. The common preparation methods of COFs include the hydrothermal method [ 23 , 24 ] and the microwave-assisted method [ 25 , 26 ], which usually have complicated operation, harsh conditions, and long reaction times and accumulate the organic solvent waste. It is necessary to explore suitable solvent systems and catalysts and conditions such as the ratio of monomers [ 27 ].…”