Spectroscopic Discrimination of Diastereomeric Complexes Involving an Axially Chiral Receptor
| Autor: | Antonello Filippi, Maurizio Speranza, Laura Guarcini, Costantino Zazza, Caterina Fraschetti, Tadashi Ema |
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| Rok vydání: | 2017 |
| Předmět: |
irmpd
Stereochemistry Electrospray ionization axial chirality enantioselectivity gas phase enantiorecognition chirality Infrared spectroscopy Protonation rotamers 010402 general chemistry 01 natural sciences Spectral line noncovalent interactions Infrared multiphoton dissociation Physical and Theoretical Chemistry Conformational isomerism IR spectroscopy macrocycles 010405 organic chemistry Chemistry Diastereomer Atomic and Molecular Physics and Optics 0104 chemical sciences Crystallography Chirality (chemistry) |
| Zdroj: | Chemphyschem : a European journal of chemical physics and physical chemistry. 18(18) |
| ISSN: | 1439-7641 |
| Popis: | The infrared multiphoton dissociation (IRMPD) spectra of electrospray ionization (ESI)-formed proton-bound complexes between the axially chiral multifunctional macrocycle MaR and d- and l-phenylalanine (PD and PL) or d- and l-3,4-dihydroxyphenylalanine (DD and DL) are recorded in the ν˜ =2800–3700 cm−1 region. Whereas the diastereomeric [MaR⋅H⋅PD]+ and [MaR⋅H⋅PL]+ complexes do not show any significant spectral differences, the spectrum of [MaR⋅H⋅DD]+ clearly diverges from that of its [MaR⋅H⋅DL]+ diastereomer. A comparison of the experimental spectra with the B3LYP/6-31G**-calculated harmonic vibrational frequencies of a number of stable structures indicates the formation, in the ESI source, of very similar spectroscopically active structures, with the protonated amino acid placed outside the flat cavity of the macrocycle and hydrogen-bonded at its O2 center. Different spectral signatures of the [MaR⋅H⋅DD]+ and [MaR⋅H⋅DL]+ complexes are attributed to the coexistence of several stable rotamers in the ESI source. |
| Databáze: | OpenAIRE |
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