Enantiomeric differentiation of β-amino alcohols under electrospray ionization mass spectrometric conditions.
The enantiomeric differentiation of a series of chiral β-amino alcohols (A) is attempted, for the first time, by applying the kinetic method using L-proline, L-tryptophan, 4-iodo-L-phenylalanine or 3, 5-diiodo-L-tyrosine as the chiral references (Ref) and Cu(2+) or Ni(2+) ion (M) as the central metal ion. The trimeric diastereomeric adduct ions, [M+(Ref)2+A-H](+), formed under electrospray ionization conditions, are subjected for collision-induced dissociation (CID) experiments. The products ions, formed by the loss of either a reference or an analyte, detected in the CID spectra are evaluated for the enantiomeric differentiation. All the references showed enantiomeric differentiation and the R(chiral) values are better for the aromatic alcohols than for aliphatic alcohols. Notably, the R(chiral) values of the aliphatic amino alcohols enhanced when Ni(2+) is used as the central metal ion. The experimental results are well supported by computational studies carried out on the diastereomeric dimeric complexes. The computational data of amino alcohols is correlated with that of amino acids to understand the structural interaction of amino alcohols with reference molecule and central metal ion and their role on the stabilization of the dimeric complexes. Application of flow injection MS/MS method is also demonstrated for the enantiomeric differentiation of the amino alcohols.
National Centre for Mass Spectrometry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, A.P., India.
R
R
Karthikraj
Ramesh Kumar
RK
Chitumalla
Kotamarthi
K
Bhanuprakash
S
S
Prabhakar
M
M
Vairamani
D000605:Amino Alcohols / Q000737:chemistry*; D008958:Models, Molecular; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013237:Stereoisomerism
D000605:Amino Alcohols
Cooks' kinetic method; amino alcohols; collision-induced dissociation; electrospray ionization mass spectrometry; enantiomeric differentiation