Alkali metal-cationized serine clusters studied by sonic spray ionization tandem mass spectrometry

摘要: Serine solutions containing salts of alkali metals yield magic number clusters the type (Ser4+C)+, (Ser8+C)+, (Ser12+C)+, and (Ser17+2C)+2 (where C = Li+, Na+, K+, Rb+, or Cs+), in relative abundances which are strongly dependent on cation size. Strong selectivity for homochirality is involved formation serine tetramers cationized by Cs+. This also case octamers smaller alkalis but there a strong preference heterochirality larger cations. Tandem mass spectrometry shows that dodecamers Cs+ dissociate mainly loss Ser4 units, suggesting neutral stable building blocks observed aggregates, (Ser8+C)+ (Ser12+C)+. Remarkably, although units formed with homochirality, they aggregate further regardless their handedness and, therefore, nominally racemic 4D:4L structure an overall heterochiral preference. The therefore represent new cluster ion homochiral its internal subunits, then assemble random fashion to form octamers. We tentatively interpret these as consequence assembly molecules around central metal ion. data provide additional evidence octamer readily ions.