Online-Monitoring of the Enantiomeric Ratio in Microfluidic Chip Reactors Using Chiral Selector Ion Vibrational Spectroscopy.

A novel experimental approach for the rapid online monitoring of the enantiomeric ratio of chiral analytes in solution is presented. The charged analyte is transferred to the gas phase by electrospray. Diastereomeric complexes are formed with a volatile chiral selector in a buffer-gas-filled ion guide held at room temperature, mass-selected, and subsequently spectrally differentiated by cryogenic ion trap vibrational spectroscopy.

Impact of anion polarizability on ion pairing in microhydrated salt clusters.

Despite longstanding interest in the mechanism of salt dissolution in aqueous media, a molecular level understanding remains incomplete. Here, cryogenic ion trap vibrational action spectroscopy is combined with electronic structure calculations to track salt hydration in a gas phase model system one water molecule at a time. The infrared photodissociation spectra of microhydrated lithium dihalide anions [LiXX'(HO) ] (XX' = I, ClI and Cl; = 1-3) in the OH stretching region (3800-2800 cm) provide a detailed picture of how anion polarizability influences the competition among ion-ion, ion-water and water-water interactions.

Isomer-Specific Vibrational Spectroscopy of Microhydrated Lithium Dichloride Anions: Spectral Fingerprint of Solvent-Shared Ion Pairs.

The vibrational spectroscopy of lithium dichloride anions microhydrated with one to three water molecules, [LiCl (H O) ] , is studied in the OH stretching region (3800-2800 cm ) using isomer-specific IR/IR double-resonance population labelling experiments. The spectroscopic fingerprints of individual isomers can only be unambiguously assigned after anharmonic effects are considered, but then yield molecular level insight into the onset of salt dissolution in these gas phase model systems. Based on the extent of the observed frequency shifts Δν of the hydrogen-bonded OH stretching oscillators solvent-shared ion pair motifs (<3200 cm ) can be distinguished from intact-core structures (>3200 cm ).