Designed Synthesis of a 2D Porphyrin‐Based sp²Carbon‐Conjugated Covalent Organic Framework for Heterogeneous Photocatalysis

Abstract

The construction of stable covalent organic frameworks (COFs) for various applications is highly desirable. Herein, we report the synthesis of an ovel two-dimensional (2D) porphyrin-based sp 2 carbon-conjugated COF (Por-sp 2 c-COF), which adopts an eclipsed AA stacking structure with aB runauer-Emmett-Teller surface area of 689 m 2 g À1 .Owing to the C = Cl inkages,P or-sp 2 c-COF shows ah igh chemical stability under various conditions,e ven under harsh conditions such as 9 m HCl and 9 m NaOH solutions.Interestingly,Por-sp 2 c-COF can be used as ametal-free heterogeneous photocatalyst for the visible-light-induced aerobic oxidation of amines to imines.M ore importantly,i nc omparison to iminelinked Por-COF,the inherent structure of Por-sp 2 c-COF equips it with several advantages as ap hotocatalyst, including reusability and high photocatalytic performance.T his clearly demonstrates that sp 2 carbon-linked 2D COFs can provide an interesting platform for heterogeneous photocatalysis.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Photocatalytic Oxidation Reactions Mediated by Covalent Organic Frameworks and Related Extended Organic Materials

“…Furthermore, the presence of two different α-CH bonds in asymmetric dibenzylamines can compromise the chemoselectivity, since it can be found two different oxidized products. As a consequence, the oxidation of symmetric dibenzylamine is the chosen reaction for the study of these coupling reactions, while asymmetric dibenzylamine examples still remain challenging ( Chen et al, 2019a ; Chen et al, 2019b ). Both oxygen anion radical and singlet oxygen have been found as reactive oxygen species in this process.…”

“…This reaction has been achieved by the following materials: a) three new benzoxazole-linked COFs, ( LZU-190 ) obtained in 2018 ( Wei et al, 2018 ), b) an imine-linked COF obtained in 2019 through the self-condensation of an aldehyde and amine containing tetratopic building block, ( Wojaczyńska and Wojaczyński, 2010 ; Lu et al, 2019 ; Lu et al, 2020 ), c) three imine-based undecorated COFs with different architectures and morphologies ( Huang et al, 2017 ). e) Oxidative Coupling: Firstly, the coupling imine product from primary amines was obtained using Por-sp 2 c-COF (porphyrin-containing COF) as photocatalyst combined with TEMPO as co-catalyst and oxygen as the final oxidant ( Chen et al, 2019a ; Chen et al, 2019b ; Liu et al, 2020a ; López-Magano et al, 2020b ). Also, benzylamine was oxidized using TFPT-BMTH (hydrazone-based COF) and water as solvent.…”

“…e) Oxidative Coupling: Firstly, the coupling imine product from primary amines was obtained using Por-sp 2 c-COF (porphyrin-containing COF) as photocatalyst combined with TEMPO as co-catalyst and oxygen as the final oxidant ( Chen et al, 2019a ; Chen et al, 2019b ; Liu et al, 2020a ; López-Magano et al, 2020b ). Also, benzylamine was oxidized using TFPT-BMTH (hydrazone-based COF) and water as solvent.…”

Ether-linked porphyrin covalent organic framework with broadband optical switch

“…As a unique and novel crystalline porous material with structural periodicity and inherent porosity of uniform topology, covalent organic frameworks (COFs) ( Côté et al., 2005 ), which were for the first time successfully synthesized by Yaghi et al. through molecular building blocks in 2005, have received considerable attention and inspired numerous people's research enthusiasm due to their great application potential in gas storage and separation, drug delivery, smart sensors, molecular catalysis, energy storage, photonic and optoelectronic devices ( Zeng et al., 2016 ; Ashraf et al., 2020 ; Sun et al., 2018 ; Ghazi et al., 2016 ; Bhunia et al., 2017 ; Keller et al., 2017 ; Dalapati et al., 2013 ; Peng et al., 2017 ; Biswal et al., 2019 ; Samal et al., 2019 ; Chen et al., 2019 ; Lu et al., 2019 ; Zhang et al., 2020 ; Quertinmont et al., 2020 ). In comparison with the three-dimensional (3D) COFs, the two-dimensional (2D) COFs are more promising because of two factors: (1) the degree of lateral conjugation from π orbitals present throughout the individual 2D layer and (2) the inherent π-π stacking between the two adjacent layers ( Bhunia et al., 2017 ).…”

Aqueous assembly of a (pseudo)rotaxane with a donor–π–acceptor axis formed by a Knoevenagel condensation

“…To the best of our knowledge, examples taking advantage of the dynamic nature of the Knoevenagel condensation 32 are limited to the syntheses of two rotaxanes 22,23 comprising cyclodextrin-encapsulated cyanine dyes under aqueous basic conditions. More frequent use of the Knoevenagel condensation is observed in the field of covalent organic frameworks 33,34 and macrocyclizations. 35 We thus explored the potential of the Knoevenagel condensation as stoppering reaction for pseudorotaxanes assembled in water (Scheme 1a).…”