Copper complexes formed by 3,5-bis(2,2′-bipyridin-4-ylethynyl)benzoic acid and its methyl and ethyl esters as studied by electrospray ionization mass spectrometry

• Published in: Central European journal of chemistry Vol. 11; no. 12; pp. 2066 - 2075
• Main Authors: Frański, Rafał, Kowalska, Marta, Czerniel, Joanna, Zalas, Maciej, Gierczyk, Błażej, Cegłowski, Michał, Schroeder, Grzegorz
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.12.2013; Versita; De Gruyter
• Subjects: Biochemistry; Biological and Medical Physics; Biophysics; Bipyridine; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Copper complexes; Electrospray ionization mass spectrometry; Geochemistry; Research Article; Electrospray ionization mass spectrometry; Bipyridine; Copper complexes
• ISSN: 1895-1066; 2391-5420; 1644-3624; 2391-5420
• DOI: 10.2478/s11532-013-0324-2

Electrospray ionization mass spectrometry was used to study the complexes of ligands containing two bipyridine units, namely 3,5-bis(2,2-bipyridin-4-ylethynyl)benzoic acid (1) and its methyl and ethyl esters (2, 3), with copper cation, with CuCl 2 as a source of copper. It was found that the type of complexes formed strongly depends on CuCl 2 concentration. At lower CuCl 2 concentration, the detected complexes were rather simple and some of them were formed upon electrospray ionization conditions e.g. ions [2 2 +Cu 2 ] 2+ and [3 2 +Cu 2 ] 2+ (complexes ligand-Cu(I) of stoichiometry 2:2) which are analogical to the well known, for quaterpyridine, helical complexes. At higher CuCl 2 concentration, the detected complexes were more complicated, and most of them contained copper cations bridged by chlorides. The largest ions were [L 2 +Cu 4 Cl 6 ] 2+ . The CID MS/MS spectra of these ions allowed determination of their mass spectrometric fragmentation pathways and as a consequence their structure elucidation.