Characterization of amino acids complexes with cyclodextrins in the gas phase using electrospray ionization Fourier transform mass spectrometry

The first chapter provides general properties and applications of cyclodextrins and their complexes. Briefly, the mechanism of inclusion complexes and the enantioselectivity for mass spectrometry using cyclodextrin complexes are discussed. It also explains the mechanism, instrumentation, application of electrospray ionization (ESI) source and Fourier transform mass spectrometry (FTMS). 4.7T Home-built mass spectrometry is also presented used for experiments.; The second chapter introduces a novel gas-phase guest exchange reaction of cyclodextrin and amino acids complexes with alkylamines. This guest exchange reaction is sensitive to the chirality of amino acids providing evidence of gas-phase inclusion complexes of cyclodextrin. In this chapter, the experimental and theoretical evidence is presented to support the inclusion complexes of cyclodextrin in the gas phase.; Chapter three describes the validity of the “three-point interaction” model for enantioselectivity in the gas phase. Most natural amino acids are investigated and result in two attractive interactions and one repulsive interaction producing the best selectivity in the gas phase. The linear analogues of cyclodextrin are examined to find a better host.; The existence of the gas-phase zwitterion of amino acids is in the middle of debate until now. In the chapter four, evidence of the gas-phase zwitterionic amino acids in the cavity of cyclodextrin is presented. Zwitterionic amino acids are discovered in a trimeric complex with underivatized β-cyclodextrin unlikely with derivatized β-cyclodextrin used in previous reports. Trimer complexes are produced after a proton transfer of alkylamine from carboxyl group of amino acids. The trimeric complexes are the result of the zwitterions formation. The experimental results and molecular dynamics calculations confirm the existence of the gas-phase zwitterionic amino acids inside of cyclodextrin.