Fully Conjugated Two‐Dimensional sp²‐Carbon Covalent Organic Frameworks as Artificial Photosystem I with High Efficiency

Abstract

The synthesis of fully conjugated sp2‐carbon covalent organic frameworks (COF) is extremely challenging given the difficulty of the formation of very stable carbon‐carbon double bonds (‐C=C‐). Here, we report the successful preparation of a 2D COF (TP‐COF) based on triazine as central planar units bridged by sp2‐carbon linkers through the ‐C=C‐ condensation reaction. High‐resolution‐transmission electron microscopy (HRTEM) clearly confirmed the tessellated hexagonal pore structure with a pore center‐to‐center distance of 2 nm. Powder X‐ray diffraction (PXRD) together with structural simulations revealed an AA stacking mode of the obtained layered structure. TP‐COF turned out to be an excellent semiconductor material with a LUMO energy of −3.23 eV and a band gap of 2.36 eV. Excitingly, this novel sp2‐carbon conjugated TP‐COF exhibited unprecedented coenzyme regeneration efficiency and can significantly boost the coenzyme‐assisted synthesis of l‐glutamate to a record‐breaking 97 % yield within 12 minutes.

Bioinspired NADH Regeneration Based on Conjugated Photocatalytic Systems

“…TP‐COF: Reproduced with permission. [ 91 ] Copyright 2019, Wiley‐VCH. CTF: Reproduced with permission.…”

“…In 2019, Zhao et al reported a fully conjugated COF (TP‐COF) featuring sp 2 ‐carbon linkage. [ 91 ] Upon Knoevenagel polycondensation, the as‐formed CC linkages provide COF framework with enhanced electron delocalization, which greatly increases its photon absorption. TP‐COF displays a bandgap of 2.36 eV and shows high efficiency for NADH regeneration, which could be coupled with enzyme for L‐glutamate production (Figure 9B).…”

Synthesis of Vinylene‐Linked Two‐Dimensional Conjugated Polymers via the Horner–Wadsworth–Emmons Reaction

“…[12] In particular, sp 2 -carbonlinked (or vinylene-linked) 2D CPs provide high chemical and thermal stabilities as well as complete p-conjugation over the whole 2D polymer framework, making these materials highly attractive for various applications, such as in optoelectronics, spintronics, and energy storage. [13][14][15] Thus far, only Knoevenagel [13][14][15]16] and other aldol-type condensation [17][18][19] reactions have been reported for the synthesis of crystalline vinylenelinked 2D CPs. However, Knoevenagel polycondensation provides cyano-vinylene-linked 2D CPs in which additional cyano-groups on the conjugated backbone cause structural twisting due to steric hindrance.…”

Synthese von Vinyl‐verknüpften zweidimensionalen konjugierten Polymeren via Horner‐Wadsworth‐Emmons‐Reaktion

“…B. in der Optoelektronik, Spintronik und Energiespeicherung. [13][14][15] Bisher sind nur Knoevenagel- [13][14][15]16] und andere Aldol-ähnliche Kondensations [17][18][19] -Reaktionen für die Synthese von kristallinen vinyl-verknüpften 2D CPs dokumentiert. Die Knoevenagel-Polykondensation liefert jedoch cyano-vinyl-verknüpfte 2D CPs, bei denen die zusätzlichen Cyanogruppen im konjugierten Polymerrückgrat eine strukturelle Verdrehung aufgrund sterischer Hinderung verursachen.…”