Structure of a piperidine-modified calix[4]arene derivative and spectral resolution of its interaction with rare earth metals with chemometric methods

A piperidine-modified calix[4]arene derivative was synthesized and its structure was confirmed with X-ray diffraction data. UV–visible spectroscopy was used to study its molecular recognition of rare earth ions. The results revealed the calix[4]arene derivative could separate tight metal picrate ion pairs by complexation with the rare earth metal ions in tetrahydrofuran. Resolution of the UV–visible spectra with chemometric methods revealed that the derivative and the rare earth ions Eu3+, Dy3+, and Tb3+ formed ML2 complexes with stability constants of 108.26, 108.29, and 107.41 respectively.

Graphical abstractX-ray crystal structure of the piperidine-modified calix[4]arene derivative PD–CA, which has strong molecular recognition effect to some rare earth metals as Eu3+, Dy3+ and Tb3+.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► X-ray data shows piperidine-modified calix[4]arene molecule enclosed three DMF molecules. ► UV spectra revealed it can transform metal picrate tight ion pairs into separated ones. ► Chemometric resolution of the UV spectra revealed the formation of ML2 complexes. ► The stable constants of these complexes were calculated respectively.