A Three-Dimensional sp² Carbon-Conjugated Covalent Organic Framework

Abstract

A first example of an sp2 carbon-conjugated three-dimensional (3D) covalent organic framework (COF) (BUCT-COF-4) is synthesized via the Knoevenagel condensation of the saddle-shaped aldehyde-substituted cyclooctatetrathiophene and 1,4-phenylenediacetonitrile. Ascribed to the extended π-conjugation and long-range ordered structures, BUCT-COF-4 displays high Hall electron mobility of 1.97 cm2 V–1 s–1 at room temperature. After it is doped with iodine, the material not only exhibits an enhanced electron mobility up to 2.62 cm2 V–1 s–1 in ambient air but also presents an unexpected metal-free ferromagnetic phase transition arising from the formation of aligned spins unidirectional across the whole sp2 carbon-conjugated 3D framework. This is the first report of a ferromagnetic phenomenon in 3D COF materials, which would broaden promising applications and open a new frontier in COF materials.

Fully Conjugated Tetraoxa[8]circulene‐Based Porous Semiconducting Polymers

“…Whereas most COFs are based on polarized linkages, a few examples of fully conjugated COFs through pyrazine, cyano-vinylene or vinyl-ene linkages have also been reported recently. [23] Compared to these, pTOCs maintain a higher degree of sp 2 conjugation without strongly polarizing functionalities or building blocks and furthermore demonstrate the realization of electrical conductivity with highly tunable porosity (Table S13). In order to prove that the residual Cl À ions are not contributing to the conductivity of the pTOCs, we conducted conductivity measurements of pTOC-350 after doping with NaCl, which showed a slightly reduced conductivity of 1.8 × 10 À 7 S cm À 1 (Figure S15).…”

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

“…10 COFs present a remarkable kind of porous crystalline polymer materials that are composed of organic building units through covalent bonds. 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.…”

Porous organic polymers as a platform for sensing applications

“…69 In addition, this reaction method could enable the synthesis of sp 2 -carbon conjugated POPs, which not only show excellent stability, but also extended p-conjugation, rendering the materials good candidates for multifunctional applications. 70,71 It should be noted that most of the reactions for the synthesis of POPs require anaerobic conditions and the reaction system should be degassed thoroughly. Some reactions even require additional anhydrous conditions.…”