Covalent Organic Frameworks: Synthesis, Properties and Applications—An Overview

Abstract

Covalent Organic Frameworks (COFs) are an exciting new class of microporous polymers with unprecedented properties in organic material chemistry. They are generally built from rigid, geometrically defined organic building blocks resulting in robust, covalently bonded crystalline networks that extend in two or three dimensions. By strategically combining monomers with specific structures and properties, synthesized COF materials can be fine-tuned and controlled at the atomic level, with unparalleled precision on intrapore chemical environment; moreover, the unusually high pore accessibility allows for easy post-synthetic pore wall modification after the COF is synthesized. Overall, COFs combine high, permanent porosity and surface area with high thermal and chemical stability, crystallinity and customizability, making them ideal candidates for a myriad of promising new solutions in a vast number of scientific fields, with widely varying applications such as gas adsorption and storage, pollutant removal, degradation and separation, advanced filtration, heterogeneous catalysis, chemical sensing, biomedical applications, energy storage and production and a vast array of optoelectronic solutions. This review attempts to give a brief insight on COF history, the overall strategies and techniques for rational COF synthesis and post-synthetic functionalization, as well as a glance at the exponentially growing field of COF research, summarizing their main properties and introducing the numerous technological and industrial state of the art applications, with noteworthy examples found in the literature.

Advanced Ordered Nanoporous Materials

“…High pore volume and low density of COFs serve more room for storing a high dosage of drug molecules. Moreover, the tenability of their pore structure engineered either via pre or post-modification resulting in the customized COFs improves the efficiency of drug administration to the targeted cells (Machado et al 2021). Those features also allow COFs to control the rate of diffusion and release of drugs which makes them a potential candidate as a drug carrier.…”

An Olefin‐based, Fluorescent Covalent Organic Framework for Selective Sensing of Aromatic Amines

“…Covalent organic frameworks (COFs) [20] constructed from organic building-blocks by covalent bonds, are an emerging class of crystalline porous materials and exhibit great potentials applications in various fields. [21][22][23][24] Owing to multiple identical binding site, porous structure guaranteed for the real-time response, sensing signals transmitted and amplified through the extended π-conjugation framework, [25,26] COFs has recently become a promising fluorescence sensing material. [27,28] However, the application of COF materials in fluorescence sensors mostly focused on detecting environmental samples such as nitro-explosives, [29][30][31] heavy metal ions, [32][33][34] pH, [35] humidity [36] etc.…”

β-Ketoenamine Covalent Organic Frameworks—Effects of Functionalization on Pollutant Adsorption

“…COFs are generally built from rigid, geometrically defined organic building blocks, resulting in robust, covalently bonded crystalline networks that extend in 2 or 3 dimensions [ 23 ], with a wide range of potential applications, including gas storage [ 24 ], heterogeneous catalysis [ 25 , 26 ], chemical sensing [ 27 , 28 ], optoelectronics [ 29 ], and pollutant adsorption [ 2 , 22 , 30 ]. One of the main advantages of COF materials is the ability to easily introduce pore wall modifications (either pre- or post-synthesis) without affecting the structural integrity of the resulting solid.…”