Predictive Molecular-Level Recognition of Pesticides by Co(II)-Based Coordination Polymer: A Theoretical Study of Host–Guest Interactions

Abstract

The strategic design of advanced sensing materials for pesticides is increasingly challenged by regulatory restrictions and limited experimental accessibility to several hazardous agrochemicals. This work reports a comprehensive theoretical investigation of a well-characterized Co(II)-based coordination polymer (CP), synthesized using a slow diffusion process, as a potential sensing platform for pesticide recognition. The CP has been thoroughly characterized by X-ray single-crystal diffraction analysis, and its interaction with nine representative pesticides has been systematically explored using density functional theory (DFT) and time-dependent DFT. Optimized host–guest geometries reveal favorable binding affinities driven by a combination of hydrogen bonding, electrostatic interactions, π-interactions, etc., depending on the chemical nature and molecular structure of the pesticide. Optical response, chemical reactivities, charge transfer characteristics, frontier molecular orbital analysis, and noncovalent interaction (NCI) analyses provide molecular-level insights into the recognition mechanism and relative selectivity of the CP toward different pesticides. The results demonstrate that the electronic structure of the Co(II) coordination framework is sensitively modulated upon guest binding, highlighting its potential as a sensing material. This study establishes a predictive computational sensing strategy for environmentally relevant pesticides that are difficult to access experimentally (sometimes banned) and offers valuable guidelines for the future design of CP-based sensors targeting emerging and regulated contaminants.