Abstract
Vibrational circular dichroism (VCD) studies are reported on a chiral compound in which a fullerene C60 moiety is used as an electron acceptor and local VCD amplifier for an alanine‐based peptide chain. Four redox states are investigated in this study, of which three are reduced species that possess low‐lying electronic states as confirmed by UV/Vis spectroelectrochemistry. VCD measurements in combination with (TD)DFT calculations are used to investigate (i) how the low‐lying electronic states of the reduced species modulate the amplification of VCD signals, (ii) how this amplification depends on the distance between oscillator and amplifier, and (iii) how the spatial extent of the amplifier influences amplification. These results pave the way for further development of tailored molecular VCD amplifiers.
Highlights
Circular dichroism is a spectroscopic technique sensitive to the chirality of a system that uses the difference between the absorption of left- and right-handed circularly polarised light.[1]
In the present study we have explored the suitability of the reduced forms of C60 to serve as a switchable and tuneable amplifier of Vibrational circular dichroism (VCD) signals
To this purpose C60 has been attached to an alanine-based peptide chain for which spectroelectrochemical IR absorption and VCD spectra have been recorded
Summary
Circular dichroism is a spectroscopic technique sensitive to the chirality of a system that uses the difference between the absorption of left- and right-handed circularly polarised light.[1]. Such a modulation has been achieved with an all-organic compound by reducing the compound to form a radical anion, and as a result the first electronic transition was lowered by around 16 500 cmÀ1 (neutral!radical anion) and a ten-fold increase in the VCD signal intensities was achieved.[28] Even larger amplifications (by more than two orders of magnitude) were achieved by coupling an amino acid or peptide to the low-lying electronic states of transition-metal ions.[29] Interestingly, these studies showed that the signal enhancement strongly depended on the distance between the amplifier and the atoms involved in the mode of interest This realization was the basis for the subsequent development of switchable amplifiers that could be used as a powerful local probe of chiral structure at user-defined positions in larger structures.[30]. The literature has reported on these modes before[28,29,30] allowing for a fair comparison of previous amplifiers with the C60 moiety
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
