title: Self-assembly of quaterpyridine ligands and Cu+ cation into helical complexes of 2:2 stoichiometry under electrospray ionisation conditions.
abstract: Solutions containing quaterpyridine ligand 1 and Cu(2+) cation were analysed by electrospray ionisation mass spectrometry (ESI-MS). It was found that copper reduction under ESI conditions and self-assembly of 1 and Cu(I) led to the formation of the 2:2 stoichiometry complex. Such stoichiometry is characteristic of helical complex of quaterpyridine ligand with Cu(I). The isotope pattern characteristic of [Cu(2)1(2)](2+) ion and different from that of [Cu1](+) ion, is observed. When using methanol as solvent, only [Cu(2)1(2)](2+) ions are observed in mass spectrum obtained at low cone voltage. At higher cone voltage [Cu(2)1(2)](2+) ion easy dissociates producing [Cu1](+) ion. When using other solvents studied, water and acetonitrile, 2:2 stoichiometry complex is formed, but along with complexes of other stoichiometries. Helical complex was not observed for silver cation for which only 1:1 stoichiometry complex was observed (ion [Ag1](+)).
authors.affiliation: Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Wałesa-Chorab
authors.forename: Violetta
authors.initials: V
authors.lastname: Patroniak
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Schroeder
authors.forename: Rafał
authors.initials: R
authors.lastname: Frański