CO2 Capture by Multivalent Amino-Functionalized Calix[4]arenes: Self-Assembly, Absorption, and QCM Detection Studies

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• 作者：Laura Baldini ; Monica Melegari ; Valentina Bagnacani ; Alessandro Casnati ; Enrico Dalcanale ; Francesco Sansone ; Rocco Ungaro
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：May 20, 2011
• 年：2011
• 卷：76
• 期：10
• 页码：3720-3732
• 全文大小：1208K
• 年卷期：v.76,no.10(May 20, 2011)
• ISSN：1520-6904

文摘

The reactivity of CO₂ with polyamino substrates based on calix[4]arenes and on a difunctional, noncyclic model has been studied. All the compounds react with CO₂ in chloroform to form ammonium carbamate salts. However, the number, topology, and conformational features of the amino-functionalized arms present on the multivalent scaffold have a remarkable influence on the reaction efficiency and on the product composition. Tetraaminocalix[4]arenes 1鈥?b>3 rapidly and efficiently react with 2 equiv of CO₂, yielding highly stable hydrogen-bonded dimers formed by the self-assembly of two bis-ammonium bis-carbamate intramolecular salts. 1,3-Diaminocalix[4]arene 4 absorbs 1 mol of CO₂, affording less stable zwitterionic ammonium carbamates. Gemini compound 5 reacts with CO₂ in a 1:1 stoichiometry, forming hydrogen-bonded dimers of ammonium carbamate derivatives of moderate stability. For upper rim 1,3-diaminocalix[4]arene 6, in addition to the labile intramolecular salt, the presence of a self-assembled polymer was also detected. These systems were fully characterized in solution by ¹H and ¹³C NMR spectroscopy, whereas the corresponding gas鈥搒olid reactions were further investigated by QCM measurements. Interestingly, the high affinity and reversibility of CO₂ uptake shown by 1,3-diamino calix[4]arene 4 enabled us to attain a promising QCM device for carbon dioxide sensing.