Rational design of core functionalized N-alkylated corroles for controlled film gas sensing and methanol detection

Porphyrinoid macrocycles have long been employed as active materials in chemical sensing, relying on molecular engineering of peripheral functionalization to direct the formation of ordered, supramolecular architectures. In contrast, modifications at the macrocyclic core have predominantly involved metal insertion into the inner cavity, whereas the introduction of organic functional groups directly at the core has been comparatively less explored. In contrast, this study investigates an alternative N-alkylation strategy to modulate molecular organization and fine-tune sensitivity and selectivity in gas-sensing devices. Transferring the alkyl chains from the periphery to the corrole core inverts the conventional design paradigm for porphyrinoid-based sensing materials, enabling a more direct control over molecular packing and analyte diffusion. We synthesized 11 compounds, differing in alkyl chain length, branching, and substitution pattern, and integrated them into quartz microbalance (QMB) transducers to construct an innovative corrole-based electronic nose. Systematic exposure to Volatile Organic Compounds (VOCs) revealed that N-alkylation effectively tunes the sensitivity and selectivity profiles according to the alkylated groups, their position, and, ultimately, the molecule charge. Unlike classical approaches, correlation analyses and multivariate data treatment confirmed that alkylation preserves selective interactions while reducing the contribution of non-specific dispersion forces. As a proof-of-concept, the optimized sensor array successfully discriminated methanol adulteration in both real and synthetic wine samples, achieving a near-perfect classification with low estimation error for methanol concentration. This approach establishes N-alkylation as a promising alternative to metallation for the rational design of porphyrinoid-based e-noses, offering a versatile and scalable strategy for detecting methanol and other contaminants in complex matrices.