Porphyrin‐Based COF 2D Materials: Variable Modification of Sensing Performances by Post‐Metallization

Abstract

2D nanomaterials with flexibly modifiable surfaces are highly sought after for various applications, especially in room-temperature chemiresistive gas sensing. Here, we have prepared a series of COF 2D nanomaterials (porphyrin-based COF nanosheets (NS)) that enabled highly sensitive and specific-sensing of NO 2 at room temperature. Different from the traditional 2D sensing materials, H 2 -TPCOF was designed with a largely reduced interlayer interaction and predesigned porphyrin rings as modifiable sites on its surfaces for postmetallization. After post-metallization, the metallized M-TPCOF (M = Co and Cu) showed remarkably improved sensing performances. Among them, Co-TPCOF exhibited highly specific sensing toward NO 2 with one of the highest sensitivities of all reported 2D materials and COF materials, with an ultra-low limit-of-detection of 6.8 ppb and fast response/recovery. This work might shed light on designing and preparing a new type of surface-highly-modifiable 2D material for various chemistry applications.

Three-dimensional porphyrin-based covalent organic frameworks withstptopology for an efficient electrocatalytic oxygen evolution reaction

“…Benefiting from their high crystallinity and unique pore structures, 1,2 covalent organic frameworks (COFs) have achieved great success in the fields of gas separation, [3][4][5] sensing, [6][7][8][9] energy storage, [10][11][12][13] and heterogeneous catalysis. [14][15][16] COFs are an ideal molecular design platform, in which a large number of building blocks can be interconnected to generate an almost infinite diversity of networks.…”

Metalated covalent organic frameworks: from synthetic strategies to diverse applications

“…In 2022, Lan and co-workers reported that Co-TPCOF prepared by post-synthetic metalation has the form of ultrathin atomic-level thick nanosheets, which is extremely important for providing fully accessible and exposed active sites that facilitate gas diffusion and sensing applications. 448 Upon exposure to a NO 2 atmosphere, NO 2 rapidly adsorbs on cobalt porphyrin to form Co–N bonds and accepts electrons to form nitrite species, leading to an increase in the hole concentration and thus allowing elevated conductivity. Once NO 2 is desorbed, electrons are released from the nitrite back to Co-TPCOF and the sensor current is restored.…”

Interpenetrating 3D Covalent Organic Framework for Selective Stilbene Photoisomerization and Photocyclization

“…Covalent organic frameworks (COFs) are a rising class of porous crystalline materials based on covalent linking interactions, showing the properties of designable structures, large surface area, well-defined crystalline structures, tunable functionality, low density, and so forth. − Due to the tunability of the COF structures, it is noted that the required functions can be easily designed, thus enabling them to be promising platforms for potential applications in gas sorption and separation, energy transformation, and heterogeneous catalysis. , Specifically, these characteristics can render interesting structural characteristic research platforms as photocatalysts for photoisomerization or photocyclization of trans -stilbene owing to the following reasons: (i) compared with other materials with higher density, COFs with a similar quality might provide more exposed surface area and active sites; (ii) the pore structures (e.g., pore size, inner pore environments, or interpenetration degree) can be specially designed with possible pore confinement effects; and (iii) specifically selected functional groups can confer the COF structures with light adsorption, suitable band gap, and photo-oxidation ability that are conducive to generating free radicals for selective trans -stilbene photoisomerization or photocyclization . Prior to this, although some examples like TpTt COF have been reported that can be applied for E -to- Z photoisomerization of trans -stilbene, the exploration of selective trans -stilbene photoisomerization and even photocyclization remains at an early stage.…”