Isomeric Dual-Pore Two-Dimensional Covalent Organic Frameworks

Abstract

Two-dimensional (2D) covalent organic frameworks (COFs) with hierarchical porosity have been increasingly recognized as promising materials in various fields. Besides, the 2D COFs with kagome (kgm) topology can exhibit unique optoelectronic features and have extensive applications. However, rational synthesis of the COFs with kgm topology remains challenging because of competition with a square-lattice topology. Herein, we report two isomeric dualpore 2D COFs with kgm topology using a novel geometric strategy to reduce the symmetry of their building blocks, which are four-armed naphthalene-based and azulene-based isomeric monomers. Owing to the large dipole moment of azulene, as-prepared azulene-based COF (COF-Az) possesses a considerably narrow band gap of down to 1.37 eV, which is much narrower than the naphthalene-based 2D COF (COF-Nap: 2.28 eV) and is the lowest band gap among reported imine-linked dual-pore 2D COFs. Moreover, COF-Az was used as electrode material in a gas sensor and exhibits high selectivity for NO 2 , including a high response rate (58.7%) to NO 2 (10 ppm), fast recovery (72 s), up to 10 weeks of stability, and resistance to 80% relative humidity, which are superior to those of reported COFbased NO 2 gas sensors. The calculation and in situ experimental results indicate that the large dipole moment of azulene boosts the sensitivity of the imine linkages. The usage of isomeric building blocks not only enables the synthesis of 2D COFs with isometric kgm topology but also provides an azulene-based 2D platform for studying the structure−property correlations of COFs.

Elaborate Modulating Binding Strength of Intermediates via Three‐component Covalent Organic Frameworks for CO2Reduction Reaction

“…[19] The higher HOMO value of the multi-component COF illustrated its superior potential for reduction reactions compared to CoTAPP-PATA-COF and CoTAPP-TAPZ-COF. [20] The CO 2 RR performance of these four COFs was measured using H-cell equipment in 0.5 M KHCO 3 under CO 2 atmosphere within the applied potential range of À 0.5 to À 1.0 V vs. reversible hydrogen electrode (RHE). The linear sweep voltammetry (LSV) curves exhibited that the CoTAPP-PATA-COF, CoTAPP-TAPZ-COF and Co-TAPP-PATA-TAPZ-COF possessed higher current density in CO 2 atmosphere than in Ar atmosphere, revealing their efficient electrocatalytic CO 2 RR activity (Figure S34).…”

Elaborate Modulating Binding Strength of Intermediates via Three‐component Covalent Organic Frameworks for CO2Reduction Reaction

“…[19] The higher HOMO value of the multi-component COF illustrated its superior potential for reduction reactions compared to CoTAPP-PATA-COF and CoTAPP-TAPZ-COF. [20] The CO 2 RR performance of these four COFs was measured using H-cell equipment in 0.5 M KHCO 3 under…”

Self-Template Hydrothermal Synthesis of Vinylene-Linked Covalent Organic Framework Nanosheets Confined at the Molecule/Water Interface for an Organic Memristor

“…In previous work on the solvothermal synthesis of covalent organic frameworks (COFs) presented in Figure a, highly polar organic solvents such as dioxane, dimethylformamide, and dimethylacetamide were employed to enhance the solubility of the monomers. − In contrast, in our current study, as illustrated in Figure b, water with low cost and environmental sustainability was used as the green reaction media. The vinylene-linked COF was successfully synthesized via the confined molecule/water interface, which was different from the homogeneous phase typically formed in conventional solvothermal reactions.…”