Guest-adaptive molecular sensing in a dynamic 3D covalent organic framework

Abstract

Molecular recognition is an attractive approach to designing sensitive and selective sensors for volatile organic compounds (VOCs). Although organic macrocycles and cages have been well-developed for recognising organics by their adaptive pockets in liquids, porous solids for gas detection require a deliberate design balancing adaptability and robustness. Here we report a dynamic 3D covalent organic framework (dynaCOF) constructed from an environmentally sensitive fluorophore that can undergo concerted and adaptive structural transitions upon adsorption of gas and vapours. The COF is capable of rapid and reliable detection of various VOCs, even for non-polar hydrocarbon gas under humid conditions. The adaptive guest inclusion amplifies the host-guest interactions and facilitates the differentiation of organic vapours by their polarity and sizes/shapes, and the covalently linked 3D interwoven networks ensure the robustness and coherency of the materials. The present result paves the way for multiplex fluorescence sensing of various VOCs with molecular-specific responses.

Saturated Linkers in Two-Dimensional Covalent Organic Frameworks Boost Their Luminescence

“…Two-dimensional covalent organic frameworks (2D COFs) incorporate predesigned organic units into crystalline lattices through covalent bonds. , Their topology is determined by the geometry and size of the monomeric building blocks, which can also make possible versatile chemical functions . Due to their (i) ample surface areas, (ii) ordered channels, and (iii) controllable pore sizes, 2D COFs show promise for applications including gas and energy storage, , chemical separation , and sensing, − photodetection, and photocatalysis. − …”

Lanthanide Functionalized Covalent Organic Frameworks Hybrid Materials for Luminescence Responsive Chemical Sensing

“…The possible mechanism is related to the intramolecular hydrogen bonds and protonation or deprotonation process [43,58,61–63] Organic molecules [64–60] . (a) Volatile organic compounds (VOCs).…”

“…These complex pressure-dependent luminescence responses result from the different hostguest and guest-guest interactions in the adaptive molecular pockets. [64] Besides, two imine-linked chiral luminescent 2D COFs by an enantiopure BINOL-based linear dialdehyde and a tris(4-aminophenyl) benzene derivative or tetrakis(4aminophenyl)ethene as building blocks, whose flexible tetraphenylethylene units can be readily exfoliated into ultrathin 2D nanosheets and electrospun to make freestanding nanofiber membrane. Both the solution and membrane systems show the luminescence quenching by chiral odor vapors via supramolecular effect.…”

Three-Dimensional Covalent Organic Frameworks with pts Topology for Controlled Anticancer Drug Delivery

“…Covalent organic frameworks (COFs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] represent a new class of extended crystalline solids characterized by open frameworks, that encompass void spaces (pores) and are composed of organic building blocks held together by robust covalent bonds. Attributed to their molecular designability, unique pore environments, and functional modularity, COFs have become increasingly important in a wide array of applications including catalysis, 16,17 gas storage and separation, 18,19 sensing, 20,21 energy conversion and storage, 22,23 and biomedicine [24][25][26] . There is typically a fundamental trade-off between COF crystallinity and stability owing to the irreversible character of covalent interactions that undermines the crystallinity of the frameworks.…”