Theoretical unraveling the complexation and separation of uranyl–ligand complexes towards chiral R/S‐profenofos

• Published in: Applied organometallic chemistry 2022-06, Vol.36 (6), p.n/a
• Main Authors: Liu, Linfeng, Lu, Yao, Liao, Lifu, Xiao, Xilin, Nie, Changming
• Format: Article
• Language: English
• Subjects: Chemistry; chiral organophosphorus pesticide; Complexation; Coordination compounds; Density functional theory; density functional theory (DFT); Enantiomers; Infrared radiation; Ligands; Mathematical analysis; Molecular orbitals; Pesticides; Quantum theory; R/S‐profenofos; Receptors; Separation; separation factor; Toxicity; uranyl–ligand complexes
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.6686

The identification and separation of chiral pesticides R/S‐profenofos are of great significance due to different biological toxicity of chiral isomers. In the study, we designed two novel ligands: (2,2′:6′,2″‐terpyridin)‐6‐yl(5‐methoxy‐1H‐pyrazol‐1‐yl) methanethione (TMMT) and (2,2′:6′,2″‐terpyridin)‐6‐yl(5‐methoxy‐1H‐pyrazol‐1‐yl) methanone (TMMO), and taking them as ligands coordinated with uranyl, two novel complexes [Uranyl‐TMMT]2+ and [Uranyl‐TMMO]2+ as receptors were successfully constructed. The complexation and enantioselectivity of two receptors towards R/S‐profenofos as guests were systematically unraveled based on the density functional theory (DFT) method. The results showed that the receptor [Uranyl‐TMMT]2+ containing thioamide group has stronger electron donating ability than the receptor [Uranyl‐TMMO]2+ containing amide group. All analyses including Mayer bond order (MBO), quantum theory of atoms in molecules (QTAIM), localized orbital locator (LOL) function, molecular orbital, and infrared spectrum illustrated that the UX (X = S, O) bonds play a larger role than the UN bonds in the selective complexation of receptors towards guests; the US bond in [Uranyl‐TMMT]2+ is more covalent than the UO bond in [Uranyl‐TMMO]2+. The thermodynamic calculations showed that the separation factors of [Uranyl‐TMMT]2+ towards R/S‐PFFs were between 8356 and 1219 in different solvents, and the separation factors of [Uranyl‐TMMO]2+ towards R/S‐PFFs were at range of 4951–710. The separation factors exhibited that two receptors have stronger coordination and complexation ability to S‐PFF than to R‐PFF, while [Uranyl‐TMMT]2+ exhibited significantly greater recognition ability and enantioselectivity for guests R/S‐PFFs molecules than the receptor [Uranyl‐TMMO]2+. Both two receptors [Uranyl‐TMMT]2+ and [Uranyl‐TMMO]2+ could coordinate with phosphoryl oxygen of R/S‐profenofos (R/S‐PFFs), and they showed stronger coordination and complexation ability to S‐PFF than to R‐PFF. Meanwhile, receptor [Uranyl‐TMMT]2+ exhibited significantly greater recognition ability and enantioselectivity for the guests R/S‐PFFs than [Uranyl‐TMMO]2+. Thermodynamic calculations further unraveled that there are different separation factors (SFS/R) and complexation abilities of two receptors with R/S‐PFFs in different solvents; toluene is considered as a suitable solvent.