Jump to main content
Jump to site search
Access to RSC content Close the message box

Continue to access RSC content when you are not at your institution. Follow our step-by-step guide.


Issue 5, 2017
Previous Article Next Article

Developing the family of picolinate ligands for Mn2+ complexation

Author affiliations

Abstract

We have reported here a series of ligands containing pentadentate 6,6′-(azanediylbis(methylene))dipicolinic acid units that differ in the substituent present at the amine nitrogen atom (acetate: H3DPAAA; phenyl: H2DPAPhA; dodecyl: H2DPAC12A; 4-hexylphenyl: H2DPAC6PhA). The protonation constants of the hexadentate DPAAA3− and pentadentate DPAPhA2− ligands and the stability constants of their Mn2+ complexes were determined using pH-potentiometry (25 °C, 0.15 M NaCl). The mono-hydrated [Mn(DPAAA)] complex (log KMnL = 13.19(5)) was found to be considerably more stable than the bis-hydrated [Mn(DPAPhA)] analogue (log KMnL = 9.55(1)). A detailed 1H and 17O NMR relaxometric study was carried out to determine the parameters that govern the proton relaxivities of these complexes. The [Mn(DPAC12A)] complex, which contains a dodecyl lipophilic chain, forms micelles in solution characterized by a critical micellar concentration (cmc) of 96(9) μM. The lipophilic [Mn(DPAC6PhA)] and [Mn(DPAC12A)] derivatives form rather strong adducts with Human Serum Albumin (HSA) with association constants of 7.1 ± 0.1 × 103 and 1.3 ± 0.4 × 105 M−1, respectively. The X-ray structure of the complex {K(H2O)4}{[Mn(DPAAA)(H2O)]}2 shows that the Mn2+ ion in [Mn(DPAAA)] is coordinated to the six donor atoms of the ligand, a coordinated water molecule completing the pentagonal bipyramidal coordination environment.

Graphical abstract: Developing the family of picolinate ligands for Mn2+ complexation

Back to tab navigation

Supplementary files

Article information


Submitted
23 Nov 2016
Accepted
22 Dec 2016
First published
22 Dec 2016

Dalton Trans., 2017,46, 1546-1558
Article type
Paper

Developing the family of picolinate ligands for Mn2+ complexation

A. Forgács, R. Pujales-Paradela, M. Regueiro-Figueroa, L. Valencia, D. Esteban-Gómez, M. Botta and C. Platas-Iglesias, Dalton Trans., 2017, 46, 1546
DOI: 10.1039/C6DT04442E

Social activity

Search articles by author

Spotlight

Advertisements