Recognition of G-series Nerve Agents via Aryl─C─H Interactions with [6]Cycloparaphenylene: A Computational Study

Organophosphorus-containing chemical warfare agents known as nerve agents work by irreversibly inhibiting acetylcholinesterase, leading to overstimulation of cholinergic synapse followed by the cholinergic crisis and deterioration of neurotransmission. Therefore, the recognition of such nerve agents is crucial. We report conjugated hoop-shaped supramolecular [6]CPP as a host for encapsulating G-series nerve agents. The DFT calculated results revealed that the host [6]CPP forms a more stable encapsulated complex with the G-series nerve agent Tabun compared to the other nerve agents. This higher binding affinity of Tabun is governed by multiple noncovalent CH…π interactions with the electron-rich cavity of the host [6]CPP, which plays a pivotal role in fitting well inside the host cavity. The hydroxyl-substituted [6]CPP_OH showed an even larger binding affinity for the nerve agents. The atoms in molecule (AIM) and noncovalent interactions (NCI) have well corroborated the interactions of G-series nerve agents with [6]CPP host molecule. The energy decomposition analysis (EDA) suggests that the orbital contributions stabilize the formation of the complex between G-series nerve agents and the host molecules. The TD-DFT calculations and infrared spectral results suggest that the encapsulated nerve agents with host [6]CPP and [6]CPP_OH can be recognized for various applications.