Chemiresistive sensors were created from single-walled carbon nanotubes (SWCNTs) by non-covalent modification with late first-row transition metal complexes of <i>meso</i>-tetraarylporphyrins. An array device fabricated from metalloporphyrins bearing metal centers from Cr through Zn demonstrated strong responses to vapors of various volatile organic compounds (VOCs). The responses were subjected to statistical analyses that enabled the successful classification of representative VOCs into five different categories (aliphatic hydrocarbons, alcohols, ketones, aromatic hydrocarbons, and amines) with 98% accuracy. With the exception of amines, which are capable of strong charge transfer interactions, the basis of classification appears to correlate with the differences in the solubility properties of the porphyrin compounds in the various VOCs as solvents, suggesting that solvent vapors modulate the strength of interactions between the porphyrins and the nanotubes. These results further demonstrate the potential for porphyrin-functionalized SWCNT-based electronic noses for applications in inexpensive, portable chemical sensors for the identification of VOCs. Additionally, chemiresistive detectors targeted toward the detection of amine vapors were created from SWCNTs by non-covalent modification with Co <i>meso</i>-arylporphyrin complexes. We show that through changes in the metal’s oxidation state, the electron-withdrawing character of the porphyrinato ligand, and the counteranion, the magnitude of chemiresistive response to ammonia gas could be improved. The resulting devices were also shown to have sub-ppm sensitivity and high selectivity toward amines as well as good stability to air, moisture, and time. The application of these chemiresistors in the detection of biogenic amines (i.e., putrescine and cadaverine) and in the monitoring of spoilage in various raw meat samples (chicken, pork, salmon, cod) over several days was also demonstrated.

Coordination complexes in carbon nanotube composites for chemiresistive sensing

250th National Meeting (2015)

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