Jump to main content
Jump to site search

Issue 29, 2017
Previous Article Next Article

Recognition of phosphopeptides by a dinuclear copper(II) macrocyclic complex in a water : methanol 50 : 50 v/v solution

Author affiliations

Abstract

A new triethylbenzene-derived tetraazamacrocycle containing pyridyl spacers, L, was prepared and its dinuclear copper(II) complex was used as a receptor for the recognition of phosphorylated peptides in aqueous solution. A detailed study of the acid–base behaviour of L and its copper(II) complexation properties as well as of the cascade species with phosphorylated anions including two peptidic substrates was carried out in a H2O/MeOH (50 : 50 v/v) solution using different techniques, such as potentiometry, X-band EPR and DFT calculations. The association constants of the dinuclear receptor with the phosphorylated peptides and other anionic species revealed a clear preference towards phenylic phosphorylated substrates, with values ranging 3.96–5.35 log units. Single-crystal X-ray diffraction determination of the dicopper(II) complex of L showed the copper centres at a distance of 5.812(1) Å from one another, with the phosphate group of the PhPO42− substrate well accommodated between them. X-band EPR studies indicated a similar structure for this cascade complex and for the other cascade complexes with the phosphorylated anions studied. DFT studies of the [Cu2L(μ-OH)]3+ complex revealed a different conformation of the ligand that brings the two copper centres at a very short distance of 3.94 Å aided by the presence of a bridging hydroxide anion that provides a Cu⋯O⋯Cu angle of 167.3°. This complex is EPR silent, in line with the singlet ground state obtained using CASSCF(2,2) calculations and DFT calculations with the broken-symmetry approach. This species coexists in solution with a complex in a different conformation, and having a Cu⋯Cu distance of 6.63 Å, in lower percentage.

Graphical abstract: Recognition of phosphopeptides by a dinuclear copper(ii) macrocyclic complex in a water : methanol 50 : 50 v/v solution

Back to tab navigation

Supplementary files

Publication details

The article was received on 11 May 2017, accepted on 20 Jun 2017 and first published on 22 Jun 2017


Article type: Paper
DOI: 10.1039/C7DT01724C
Citation: Dalton Trans., 2017,46, 9549-9564
  •   Request permissions

    Recognition of phosphopeptides by a dinuclear copper(II) macrocyclic complex in a water : methanol 50 : 50 v/v solution

    L. M. Mesquita, P. Mateus, R. D. V. Fernandes, O. Iranzo, V. André, F. Tiago de Oliveira, C. Platas-Iglesias and R. Delgado, Dalton Trans., 2017, 46, 9549
    DOI: 10.1039/C7DT01724C

Search articles by author

Spotlight

Advertisements