The interest in enantioseparation and enantiopurification of chiral molecules has been drastically increasing over the past decades,since these are important steps in various disciplines such as pharmaceutical industry,asymmetric catalysis,a nd chiral sensing.B ye xposing racemic samples of BINOL (1,1'-bi-2-naphthol) coated onto achiral glass substrates to circularly polarized light, we unambiguously demonstrate that by controlling the handedness of circularly polarized light, preferential desorption of enantiomers can be achieved. There are currently no mechanisms knownt hat would describe this phenomenon. Our observation together with as implified phenomenological model suggests that the process of laser desorption needs to be further developed and the contribution of quantum mechanical processes should be revisited to account for these data. Asymmetric laser desorption provides us with ac ontamination-free technique for the enantioenrichment of chiral compounds.
The interest in enantioseparation and enantiopurification of chiral molecules has been drastically increasing over the past decades,since these are important steps in various disciplines such as pharmaceutical industry,asymmetric catalysis,a nd chiral sensing.B ye xposing racemic samples of BINOL (1,1'-bi-2-naphthol) coated onto achiral glass substrates to circularly polarized light, we unambiguously demonstrate that by controlling the handedness of circularly polarized light, preferential desorption of enantiomers can be achieved. There are currently no mechanisms knownt hat would describe this phenomenon. Our observation together with as implified phenomenological model suggests that the process of laser desorption needs to be further developed and the contribution of quantum mechanical processes should be revisited to account for these data. Asymmetric laser desorption provides us with ac ontamination-free technique for the enantioenrichment of chiral compounds.
We used second harmonic generation (SHG) spectroscopy to study the chiroptical properties of R-, S- and racemic (RAC-) 1,1'-Bi-2-naphthol (BINOL) films with various thicknesses, incidence angles and degrees of crystallization...
We present aspects of emerging optical activity in thin racemic 1,1 0-Bi-2-naphthol films upon irradiation with circularly polarized light and subsequent resonant two-photon absorption in the sample. Thorough analysis of the sample morphology is conducted by means of (polarization-resolved) optical microscopy and scanning electron microscopy (SEM). The influence of crystallization on the nonlinear probing technique (second harmonic generation circular dichroism [SHG-CD]) is investigated. Optical activity and crystallization are brought together by a systematic investigation in different crystallization regimes. We find crystallization to be responsible for two counteracting effects, which arise for different states of crystallization. Measuring crystallized samples offers the best signal-to-noise ratio, but it limits generation of optical activity due to self-assembly effects. For suppression of crystallization on the other hand, there is a clear indication that enantiomeric selective desorption is responsible for the generation of optical activity in the sample. We reach the current resolution limit of probing with SHG-CD, as we suppress the crystallization in the racemic sample during desorption. In addition, intensitydependent measurements on the induced optical activity reveal an onset threshold (≈0.7 TW cm −2), above which higher order nonlinear processes impair the generation of optical activity by desorption with CPL.
Exposing racemic samples of 1,1′‐bi‐2‐naphthol (BINOL) coated onto achiral glass substrates to right or left circularly polarized light leads to preferential desorption of one or the other enantiomer. In their Communication on page 15685 ff., H. Iglev, A. Kartouzian and co‐workers show how this effect can be exploited for contamination‐free enantioenrichment. A simplified phenomenological model suggests that the contribution of quantum mechanical processes should be explored.
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