Polymer-supported calix[4]arenes for sensing and conversion of NO2/N2O4

The use of simple calix[4]arenes 1a,b for NO2/N2O4 sensing and conversion is demonstrated, both in solution and in the solid state. Upon reacting with these gases, compounds la,b encapsulate reactive NO+ cations within their cavities with the formation of deeply colored (gimel(max) similar to 570 nm) charge-transfer complexes 2a,b. Further functionalization of the calix[4]arene platform is reported for attachment to solid supports. Polymer-supported calixarene material 3 was prepared, which reversibly traps NO2/N2O4 with the formation of nitrosonium storing polymer 4. Material 4 was effectively used for nitrosation of amides. (C) 2004 Elsevier Ltd. All rights reserved.