In situ generation of piperazine ring during the synthesis of dinuclear copper(II) complexes with an octadentate Schiff base ligand and investigation of the catalytic activity in the synthesis of triazoles through click reaction
The reaction of 2-hydroxybenzaldehyde and pentaethylenehexamine gave an octadentate N6O2-donor Schiff base ligand (H6L), which was used to synthesize a family of copper complexes from its reaction with different CuII salts (CuCl2⋅2H2O, Cu(NO3)2⋅3H2O or Cu(OAc)2⋅H2O) and NaN3 in methanol. These compl...
| Autores: | , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Universidad Pública de Navarra |
| Repositorio: | Academica-e. Repositorio Institucional de la Universidad Pública de Navarra |
| OAI Identifier: | oai:academica-e.unavarra.es:2454/55905 |
| Acceso en línea: | https://hdl.handle.net/2454/55905 |
| Access Level: | acceso embargado |
| Palabra clave: | Dinuclear CuII complexes In situ polyamine rearrangement Hirshfeld surface analysis Triazole synthesis Click reaction |
| Sumario: | The reaction of 2-hydroxybenzaldehyde and pentaethylenehexamine gave an octadentate N6O2-donor Schiff base ligand (H6L), which was used to synthesize a family of copper complexes from its reaction with different CuII salts (CuCl2⋅2H2O, Cu(NO3)2⋅3H2O or Cu(OAc)2⋅H2O) and NaN3 in methanol. These complexes, with general formula [Cu2(H2L’)(Cl)x(N3)2–x] (1a, x =0.88; 1b, x =0.56; 1c, x =0), were obtained in crystalline form and characterized by single crystal X-ray analysis and spectroscopic methods. The results confirmed the formation of neutral dinuclear CuII-azide complexes and indicated that the specific nature of the CuII salt precursor affects both the composition and the crystal structure of the final product because the partial presence or absence of terminal chlorido ligands leads to complexes with similar conformation of molecular structure, but with different space group and crystal packing. Complexes 1a and 1b of crystallographic two-fold symmetry, synthesized from CuCl2⋅2H2O and variable quantities of NaN3, are isomorphous and isostructural, showing only a small difference in the amount of terminal chlorido/azido ligand. In contrast, complex 1c is a polymorph of pseudo two-fold symmetry with no ligand disorder in such terminal position, which is obtained by using stoichiometric amount of NaN3 and either Cu(NO3)2⋅3H2O or Cu(OAc)2⋅H2O instead of CuCl2⋅2H2O. Moreover, the structure of the organic ligand H6L also changed during the formation of the complexes, leading to the new ligand (H2L’)2 upon generation of a rare 1,4-disubtituted piperazine central ring by in situ rearrangement of the polyamine functionality. The intermolecular interactions in the crystal packing of complex 1c were investigated by Hirshfeld surface analysis and its catalytic activity in the green synthesis of β-hydroxy-1,2,3-triazoles through azide-alkyne-epoxide cycloaddition reaction in water was confirmed to be considerable. |
|---|