Metal-dependent sensitivity modulation in chemiresistive anion sensing with meso-squaramide-substituted metalloporphyrin selectors

초록

Molecular selectors with multiple binding sites are crucial for developing highly sensitive chemical sensors by increasing the density of chemical interactions within sensing layers. However, multiple analyte binding in a single selector is challenging due to the repulsion between the analytes. Herein, we synthesized selectors (MP4SQs, M = Co, Cu, and Zn) by incorporating squaramide moieties onto metalloporphyrins (MTPyPs). The porphyrin scaffold provides a spatially arranged platform for four squaramide moieties, while the central metal modulates the electron density of the macrocycle. The anion binding properties of MP4SQs revealed deprotonation of squaramide moieties upon the addition of acetate (AcO−) and fluoride (F−). To transduce chemical interactions into electrical signals, chemiresistive sensors were developed by functionalizing MP4SQs onto poly(4-vinylpyridine)-wrapped single-walled carbon nanotubes. The sensitivity of the sensor was varied depending on the central metal, and the ZnP4SQ functionalized sensor exhibited much improved responses of 43.45 ± 2.29% and 38.75 ± 2.49% toward 167 μM of AcO− and F−, respectively. Finally, the chemiresistive sensors were integrated with a wireless communication module to demonstrate real-time and on-site detection. By adopting deep learning-based data analysis, the sensor system discriminated AcO−, F−, and interfering anions, achieving accurate concentration predictions.

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