Size matters! Fragmentation chemistry of [Cu(L)n]2 complexes of diacylglycerophosphocholines as a function of coordination number (n = 2-7)

Abstract

[Cu(L)n]2+ complexes of 1,2-dihexanoyl-sn-glycero-3- phosphocholine (L = D6PC) are formed upon electrospray ionization mass spectrometry (ESI-MS) of an 8 mM solution of D6PC with 4 mM CuCl2 in 10 mM ammonium acetate buffer, pH 6.1. The collision-induced dissociation (CID) reactions of the [Cu(L)n]2+ complexes were examined in a linear ion trap mass spectrometer. A rich fragmentation chemistry was observed, including: loss of a neutral ligand; intermolecular ligand-ligand SN2 methylation; metal ion induced ligand fragmentation via carboxylate abstraction; and phosphate abstraction. The dominant reaction channel depends on the size (n) of the complex. Thus loss of neutral ligand(s) is the sole..