Selective Toluene Separation via π–π Interactions in Cobalt sql Network Rubber Composites

Selective removal of aromatic contaminants from water matrices poses substantial difficulties in environmental remediation processes, necessitating sophisticated materials with discriminatory molecular recognition properties. Herein, we report a framework-elastomer hybrid membrane containing [Co­(4-pmntd)2(NO3)2] (4-pmntd represents N,N′-bis­(4-pyridylmethyl)­naphthalene diimide) designed for effective toluene recovery from trace aqueous environments. Systematic structural analysis employing crystallographic diffraction, gas adsorption measurements, surface electron spectroscopy, and proton nuclear magnetic resonance elucidates the material’s architectural characteristics and surface phenomena. Computational modeling through Grand Canonical Monte Carlo methods (GCMC) and dispersion-corrected density functional theory (DFT-D) illuminates the atomic-scale sorption pathways and energetic parameters. The electron-deficient naphthalene diimide rings facilitate selective π–π charge-transfer interactions with electron-rich toluene molecules. The composite demonstrates exceptional separation performance, achieving toluene detection at concentrations as low as 5.3 × 10–6 mol/L with 97.6% extraction purity and 94.0% recovery efficiency. The material operates effectively at ambient temperature with rapid separation kinetics and excellent recyclability. Computational studies confirm optimal binding sites within the framework channels, validating the selective molecular recognition mechanism. This work advances coordination-network-based separation technology, offering a sustainable solution for industrial toluene remediation with immediate applications in environmental water treatment.