Recent Advances in the Use of Covalent Organic Frameworks as Heterogenous Photocatalysts in Organic Synthesis

Abstract

Organic photochemistry is intensely developed in the 1980s, in which the nature of excited electronic states and the energy and electron transfer processes are thoroughly studied and finally well‐understood. This knowledge from molecular organic photochemistry can be transferred to the design of covalent organic frameworks (COFs) as active visible‐light photocatalysts. COFs constitute a new class of crystalline porous materials with substantial application potentials. Featured with outstanding structural tunability, large porosity, high surface area, excellent stability, and unique photoelectronic properties, COFs are studied as potential candidates in various research areas (e.g., photocatalysis). This review aims to provide the state‐of‐the‐art insights into the design of COF photocatalysts (pristine, functionalized, and hybrid COFs) for organic transformations. The catalytic reaction mechanism of COF‐based photocatalysts and the influence of dimensionality and crystallinity on heterogenous photocatalysis performance are also discussed, followed by perspectives and prospects on the main challenges and opportunities in future research of COFs and COF‐based photocatalysts.

A latent reversible ratiometric optical pH sensing probe based on phenylboronic acid for alkaline pH detection and applications in test paper and alkalotic HK-2 cells

“…[40][41][42][43] In particular, oxygen in the open air acted as the exclusive oxidant in our case. The cyanovinylene groups in DDPB exhibited great photocatalytic activity 44,45 as cyanovinylene-based materials can promote the generation of superoxide radical anions due to the extended conjugated framework and superior charge transfer. 46 The phenylboronic acid moiety of DDPB subsequently reacted with the superoxide radical anion to form the peroxide radical intermediate.…”

Nanoarchitectonics of Hollow Covalent Organic Frameworks: Synthesis and Applications

“…2 This metric is of high significance in the fabrication of COFs, which have the advantages of tailored pore sizes, large specific surface area, high chemical/thermal stability, and permanent porosity. 2 Attributing to these characteristics, COFs have been widely applied in separation, 6,7 electrocatalysis, 8 photocatalysis, 9,10 sensing, 11 energy storage, 12,13 drug delivery, 14 and environmental remediation. 15−17 It is well known that the physical/chemical properties of materials not only depend on diverse chemical components but also are highly influenced by morphological structure.…”

“…This metric is of high significance in the fabrication of COFs, which have the advantages of tailored pore sizes, large specific surface area, high chemical/thermal stability, and permanent porosity . Attributing to these characteristics, COFs have been widely applied in separation, , electrocatalysis, photocatalysis, , sensing, energy storage, , drug delivery, and environmental remediation. − …”

A Porphyrin-Based Covalent Organic Framework as Metal-Free Visible-LED-Light Photocatalyst for One-Pot Tandem Benzyl Alcohol Oxidation/Knoevenagel Condensation

“…Benefiting from covalent linking of organic building blocks, covalent organic frameworks (COFs) have emerged as a new class of soft, porous materials, with applications in catalysis, sensing, adsorption, gas/energy storage, and other various fields [ 14 , 16 , 17 , 18 , 19 ]. Similar to those documented in metal organic frameworks (MOFs), COFs represent attractive properties such as crystallinity, a large surface area, a high porosity, structural versatility, low density, and a high degree of structural stability [ 14 , 18 , 20 ].…”

“…Photocatalysis is a green and sustainable technology that is becoming extensively researched due to the advantages of using natural sunlight as an energy source, the simple infrastructure required, the low-energy consumption, and the mild reaction conditions. The application of light-assisted organic synthesis has also been growing at a fast pace over the past few years [ 16 , 25 , 26 ]. On the other hand, tandem reactions are a current front in chemical engineering, since it avoids unnecessary process steps, simplifies the reaction workup, and represents the intensification of a multi-step process [ 27 , 28 , 29 ].…”