Metal-Dependant Structural Families of Aminomethylphosphonic Acid Assemblies Differentiated by Ion Mobility Mass Spectrometry and Density Functional Theory

Herein the morphology of aminomethylphosphonic acid (AMPA)-metal aggregates are analysed by ion mobility-mass spectrometry, DFT and IRMPD spectroscopy. Matching experimental collision cross section to the DFT predicted minima allowed unambiguous assignment of [M(AMPA)(AMPA-H)]+ where M = Mg2+, Ca2+, and Mn2+. Two distinct structural families of [M(AMPA)(AMPA-H)]+ M = Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Cu2+, and Zn2+. were differentiated by ion mobility – mass spectrometry. Groupings of experimental collision cross sections were observed for a square pyramidal geometry, (M = Ca2+, Sr2+, Ba2+) versus a seesaw geometry (M = Mg2+, Mn2+, Cu2+, and Zn2+), paving the way for distinction of aggregates at the earliest stages of assembly.