Construction of Fully Conjugated Covalent Organic Frameworks via Facile Linkage Conversion for Efficient Photoenzymatic Catalysis

Abstract

Covalent organic frameworks (COFs) with improved stability and extended π-conjugation structure are highly desirable. Here, two imine-linked COFs were converted into ultrastable and π-conjugated fused-aromatic thieno­[3,2-c]­pyridine-linked COFs (B-COF-2 and T-COF-2). The successful conversion was confirmed by infrared and solid-state 13C NMR spectroscopies. Furthermore, the structures of thieno­[3,2-c]­pyridine-linked COFs were evaluated by TEM and PXRD. It is noted that a slight difference in the structure leads to totally different photoactivity. The fully π-conjugated T-COF-2 containing triazine as the core exhibited an excellent photocatalytic NADH regeneration yield of 74% in 10 min.

Solving the COF trilemma: towards crystalline, stable and functional covalent organic frameworks

“…Another reaction based on a building block predesigned for locking is the oxidative cyclization of an imine COF with pendant thiophene groups that allows the locking of the imine group into an extended heterocyclic aromatic system. 99 The transformation of the COF linkage, especially in the case of the imine transformations, was generally accompanied by the retention of crystallinity and porosity. While in some cases the porosity was reduced by the transformation, 46 in other cases it increased, possibly due to the transformation reaction cleaning the pores.…”

Nanoscale covalent organic frameworks as theranostic platforms for oncotherapy: synthesis, functionalization, and applications

“…The coupled process of the imine carbon and thiophene b-position was carried out to form a conjugated heterocyclic system. 339 Furthermore, COF-170 was transformed into cyclic carbamate and thiocarbamate-linked COFs aer three steps, namely, demethylation by BBr 3 , imine reduction by NaCNBH 3 , and cyclization by 1,1 0 -carbonyldiimidazole or 1,1 0 -thiocarbonyldiimidazole ( Fig. 59C).…”

Facile assembly of a graphitic carbon nitride film at an air/water interface for photoelectrochemical NADH regeneration

“…First, the CNS have a higher surface area, providing more surface active sites for the photocatalytic reactions and facilitating the surface accessibility of the reactants. 38,39 Second, the reduced thickness in the nanosheets significantly shortens the migration distance of the photogenerated charges from the bulk to the surface, thus enhancing the possibility of them participating in surface redox reactions. 40 However, the use of TEOA as an electron donor may result in the accumulation of the oxidized state of TEOA + in the photochemical reaction system, which will deactivate the enzymes and also lead to their separation from the enzymatic reaction products.…”