Metal-dependant structural families of aminomethylphosphonic acid assemblies differentiated by ion mobility mass spectrometry and density functional theory

Abstract

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)]⁺ where 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.