Molecular structure regulation and herbicidal activity of dibutyltin aryloxyacetate complexes

•Six dibutyltin aryloxyacetate with skeletal isomerization have been prepared.•The different supramolecular structures of complexes have been discussed.•The three complex B1 polymorphs have been determined by TGA and DSC.•Dibutyltin aryloxyacetate exhibited potent herbicidal activity. Six dibutyltin aryloxyacetate complexes [(X-C6H4OCH2COO)(SnBu2)2(μ3O)(OMe)]2 (A1, B1), [(X-C6H4OCH2COO)2(SnBu2)2(μ3O)]2 (A2, B2), and [(X-C6H4OCH2COO)2SnBu2] (A3, B3) were synthesized and characterized by IR, NMR, HRMS, and TGA techniques. The molecular structure of complexes A1, A3 and B1-B3 was confirmed by single-crystal X-ray crystallography. Complexes A1, B1, A2, and B2 are dimeric carboxylate tetraorganodistannoxanes, displaying a "ladder-like" molecular arrangement. The aryloxyacetate ligands in A1 and B1 adopt a monodentate mode, while they function as bridging coordination ligands in A2 and B2. Complexes A3 and B3 represent dibutyltin carboxylates with crystallographically imposed two-fold symmetry, with the aryloxyacetate ligands adopting a bidentate mode. Aryloxyacetic acids demonstrate a propensity for assuming various coordination modes, leading to the formation of diverse molecular architectures in organotin carboxylates. In addition, complex B1 exhibits polymorphism. Echinochloa crus-galli and Portulaca oleracea L. were used as target organisms for herbicidal activity testing using a petri dish method. It was found that they have a significant inhibitory effect on weed roots and stems at 200 μmol/L, and the structure-activity relationship analysis revealed the important influence of substituent types and complex structures on their activity. [Display omitted]