Cavitand-Functionalized SWCNTs for N-Methylammonium Detection

Marco Dionisio†‡, Jan M. Schnorr†, Vladimir K. Michaelis§, Robert G. Griffin§, Timothy M. Swager*†, and Enrico Dalcanale*‡

^† Department of Chemistry and Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States

^‡ Dipartimento di Chimica Organica e Industriale,Università di Parma, and INSTM, UdR Parma, Parco Area delle Scienze 17A, 43124 Parma, Italy

^§ Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/ja301174m

Publication Date (Web): April 4, 2012

Copyright © 2012 American Chemical Society

Single-walled carbon nanotubes (SWCNTs) have been functionalized with highly selective tetraphosphonate cavitand receptors. The binding of charged N-methylammonium species to the functionalized SWCNTs was analyzed by X-ray photoelectron spectroscopy and confirmed by ³¹P MAS NMR spectroscopy. The cavitand-functionalized SWCNTs were shown to function as chemiresistive sensory materials for the detection of sarcosine and its ethyl ester hydrochloride in water with high selectivity at concentrations as low as 0.02 mM. Exposure to sarcosine and its derivative resulted in an increased conductance, in contrast to a decreased conductance response observed for potential interferents such as the structurally related glycine ethyl ester hydrochloride.