Chiral recognition in the gas phase: Mass spectrometric studies of diastereomeric cobalt complexes

Abstract

Results of mass analyzed ion kinetic energy (MIKE) spectra and kinetic energy release (KER) measurements of diastereomeric octahedral cobalt complexes indicate that these diastereomers can be distinguished in the gas phase. Four alkyl tartrate esters were complexed to cobalt trisacetylacetonate (Co(acac)3) in the presence of a chiral auxiliary, RR- and SS-threohydrobenzoin. Different KER values of the product ion generated from [Co(acac)2/D- or L-diisopropyl tartrate](+) reflect differences in the precursor ion structure. The dissociation pathway resulting in this product ion is believed to arise via a hydride transfer from the acetylacetonate ligand to the metal center with subsequent loss of neutral organic species. It has been established that two conditions are necessary for observation of chiral recognition in this system; (1) the cobalt complex must be octahedral and (2) a chemical kinetic resolving agent must be present during formation of the complex.

Molecular recognition and supramolecular chemistry in the gas phase

“…The chiral recognition ratios R as given in Equation 2 vary between 0.3 and 3 for 19 different amino acids under study (Yao et al, 1999). The tartrates have also been studied as transition metal complexes (Dang et al, 1994;Arakawa et al, 2000). Thus, it seems obvious to examine the chirality effects in transition metal complexes of amino acids.…”

A review of recent advances in mass spectrometric methods for gas-phase chiral analysis of pharmaceutical and biological compounds

“…The gas-phase mass spectrometric methods that have been extensively developed fall into five main categories: (1) the kinetic method formalism , (2) host-guest (H-G) diastereomeric adduct formation [53][54][55][56][57][58][59][60][61][62][63][64][65][66][67], (3) ion/molecule (equilibrium) reactions [68][69][70][71][72][73][74][75], (4) CID of diastereomeric adducts [76][77][78], and (5) the emerging technique of ion mobility spectrometry (IMS) [131][132][133][134][135][136]. These methods along with other mass spectrometric approaches [79][80][81][82][83][84][85][86][87][88][89] provide a fast means for gas-phase chiral analysis.…”

Molecular recognition properties of tartrates and metal‐tartrates in solution and gas phase

“…+ (acac = acetylacetonate ion) and it was concluded that the presence of a chemical kinetic resolving agent like RR-or SS-threohydrobenzoyn (THB) is essential for this chiral recognition system [71]. The enantiomers of analytes, such as isopropyl threo-and erythro-3-cyclohexylglycerates, 2,3-butanediol, trans-1,2-cyclohexanediol, and 1,4-dimethoxy-2,3-butanediol were studied in the gas phase by CI-MS using labeled diisopropyl tartrates as a chiral reference [75].…”