Issue 10, 2018

Complexes of phosphonate and phosphinate derivatives of dipicolylamine

Abstract

Four dipicolylamine (DPA) derivatives bearing methylphosphonic or methylphosphinic acid (P–R; R = H, Me, CH2PO2H2) groups were synthesized. Their acid–base and coordination properties were studied by potentiometry, UV-Vis and NMR measurements. The phosphonate derivative shows increased basicity (log K1 = 8.39), whereas the phosphinate derivatives show decreased basicity (log K1 = 6–7) compared to the parent dipicolylamine. Consequently, the stability constants of the phosphonate complexes are 3 to 4 orders of magnitude higher than those of the phosphinate complexes. All ligands show excellent selectivity for Zn(II) over Ca(II) and Mg(II) ions. The structures of several Cu(II) and Ni(II) complexes in the solid state were determined by X-ray diffraction analysis. The complexes mostly show dimeric or polymeric structures and the two metal ions induce a different coordination geometry of the DPA group. The coordination geometry is always (pseudo)octahedral. The DPA fragment is bound in mer geometry in the Cu(II) complexes, whereas the Ni(II) complexes have fac geometry. In conclusion, the phosphonate and phosphinate derivatives of DPA are efficient complexing agents for divalent transition metal ions and the DPA-phosphinate grouping is a suitable fragment for sensing Zn(II) ions.

Graphical abstract: Complexes of phosphonate and phosphinate derivatives of dipicolylamine

Supplementary files

Article information

Article type
Paper
Submitted
07 jan 2018
Accepted
24 mrt 2018
First published
26 mrt 2018

New J. Chem., 2018,42, 7713-7722

Complexes of phosphonate and phosphinate derivatives of dipicolylamine

V. Hlinová, A. Jaroš, T. David, I. Císařová, J. Kotek, V. Kubíček and P. Hermann, New J. Chem., 2018, 42, 7713 DOI: 10.1039/C8NJ00100F

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