Facile construction of fully sp2-carbon conjugated two-dimensional covalent organic frameworks containing benzobisthiazole units

Abstract

Developing a facile strategy for the construction of vinylene-linked fully π-conjugated covalent organic frameworks (COFs) remains a huge challenge. Here, a versatile condition of Knoevenagel polycondensation for constructing vinylene-linked 2D COFs was explored. Three new examples of vinylene-linked 2D COFs (BTH-1, 2, 3) containing benzobisthiazoles units as functional groups were successfully prepared under this versatile and mild condition. The electron-deficient benzobisthiazole units and cyano-vinylene linkages were both integrated into the π conjugated COFs skeleton and acted as acceptor moieties. Interestingly, we found the construction of a highly ordered and conjugated D-A system is favorable for photocatalytic activity. BTH-3 with benzotrithiophene as the donor with a strong D-A effect exhibited an attractive photocatalytic HER of 15.1 mmol h−1g−1 under visible light irradiation.

The effect of enantioselective chiral covalent organic frameworks and cysteine sacrificial donors on photocatalytic hydrogen evolution

“…Especially for photosynthesis, the crystalline 2D COFs exhibit remarkable superiority compared to the other known amorphous organic photocatalysts 28 – 30 . The photocatalytic functionality has been promoted by incorporating photosensitizing groups in building blocks 31 , 32 , constructing donor-acceptor on skeletons 33 – 35 , and extending π-electron conjugation along backbones 36 – 38 . Consequently, COF-related photocatalysts are bestowed with broad-band absorptivity and high photogenerated charge mobility.…”

Facile construction of olefin-linked covalent organic frameworks for enhanced photocatalytic organic transformation via wall surface engineering

“…11,12 With a well-dened pore structure, promising stabilities and fascinating opto-electronic properties, 13 COFs had shown enormous potential for application in various elds including gas adsorption 14 and separation, 15 sensing, [16][17][18][19] biomedicine, 20,21 energy storage, 22,23 optoelectronics, [24][25][26] and catalysis. [27][28][29][30] Particularly, due to the regular pore structure, considerable stability and extended p-conjugated framework, COFs hold much potential for photocatalysis. However, most of these COFs based on imine, azine or b-ketoenamine-linkers limited the light absorption, charge separation and stability of the materials.…”

Modulating electronic structure of triazine-based covalent organic frameworks for photocatalytic organic transformations

“…22,23 Benefiting from these features, COFs have emerged as promising platforms for potential applications in membrane separation, 24,25 luminescence 26 and sensors, 27 proton conduction, 28,29 energy storage 30,31 and heterogeneous catalysis. 32–34 In particular, 2D COFs have great advantages in heterogeneous catalysis, including: (i) the band gap and visible light absorption ability of 2D COFs can be easily adjusted by changing the building block; 35 (ii) the ordered π-conjugated structure and π–π stacking in inter-layers are in favour of delocalization of electrons; 36,37 (iii) 2D COFs offer a unique 1D nanopore channel, and the charges can transfer to the surface of the catalyst through this channel; 38 (iv) benefiting from the introduction of donor (D) and acceptor (A) components in 2D COFs, the constructed COFs possess effective separation of electron–hole pairs. 39–41 Therefore, 2D COFs can be promising candidates in visible light-induced organic transformation.…”