https://doi.org/10.15255/KUI.2004.010
Published: Kem. Ind. 54 (2) (2005) 57–63
Paper reference number: KUI-10/2004
Paper type: Original scientific paper
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Sensing and Fixation of NO₂ by Calixarenes

D. M. Rudkevich

Abstract

In this short review, an approach towards visual detection, conversion and use of NO₂ is described, which applies methods and techniques of supramolecular chemistry and employs calix[4]arenes. Exposure of alkylated calix[4]arenes to NO₂/N₂O₄, both in chlorinated solvents and in the solid state, results in deeply colored calixarene-nitrosonium (NO⁺) complexes. NO⁺ were found encapsulated within the calixarene cavities, and stable charge-transfer complexes resulted with Kassoc > 106 dm³ mol⁻¹ (CDCl₃). The complexation process is reversible, and the complexes dissociate upon addition of water and alcohol, recovering the parent calixarenes. Attachment of calix[4]arenes to silica gel was demonstrated, which afforded a solid material for visual detection and entrapment of NO₂/N₂O₄. Design and synthesis of calixarene-based nanotubes for trapping NO₂/N₂O₄ was proposed. Chemical utilization of NO₂/N₂O₄ was demonstrated through the transformation into calixarene-NO⁺ complexes and their use as nitrosonium storing and transferring reagents for organic synthesis. These findings open wider perspectives towards NO₂/NOₓ sensing, storing and converting materials.

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Keywords

calixarenes, nitrogen oxides, polymers, sensors, supramolecular chemistry