Abstract
Chirality, the absence of mirror symmetry, governs behavior in most biologically important molecules, thus making the chiral recognition of great importance in the pharmaceutical and agrochemical industries, as well as medicine. Chiral molecules can be characterized by means of optical experiments based on chiro-optical excitation of molecules. Specifically, chiral absorptive materials differently absorb left- and right-circular polarized light, i.e., they possess circular dichroism (CD). Unfortunately, the natural CD of most molecules is very low and lies in the ultraviolet range. Fluorescence-detected CD is a fast and sensitive tool for investigation of chiral molecules which emit light; ultralow CD in absorption can be detected as the difference in emission. In this work, we perform fluorescence-detected CD on novel chiral amide compounds, designed specifically for visible green emission; we synthesize two enantiomeric fluorescent compounds using low-cost starting compounds and easy purification. We investigate different solutions of the enantiomers at different concentrations, and we show that the fluorescence of the intrinsically chiral compounds depends on the polarization state of the penetrating light, which is absorbed at 400 nm and emits across the green wavelength range. We believe that these compounds can be coupled with plasmonic nanostructures, which further shows promise in applications regarding chiral sensing or chiral emission.
Highlights
Chirality, the lack of the mirror symmetry, is a general property found in nature, governing biochemical reactions of most important molecules
The intrinsic lack of mirror symmetry leads to the differential absorption when the chiral molecule is excited by left- and rightcircular polarized light (LCP and RCP, respectively); this property is called electronic circular dichroism (ECD)
Was expected to offer higher sensitivity and specificity of chiral detection. It was previously applied in the detection of structural change in the tertiary structure of metmyoglobin [13], as well as in exciton-coupled stereochemical analysis [14,15], and it was proposed for measurements of the enantiomeric excess in substances containing randomly orientated absorbing molecules [16]; fluorescence-detected circular dichroism (FDCD) was used in attempts to detect single-molecule chirality [17,18,19]
Summary
The lack of the mirror symmetry, is a general property found in nature, governing biochemical reactions of most important molecules. Being a fluorescence-based characterization, FDCD was expected to offer higher sensitivity and specificity of chiral detection It was previously applied in the detection of structural change in the tertiary structure of metmyoglobin [13], as well as in exciton-coupled stereochemical analysis [14,15], and it was proposed for measurements of the enantiomeric excess in substances containing randomly orientated absorbing molecules [16]; FDCD was used in attempts to detect single-molecule chirality [17,18,19]. We design chiral compounds to exhibit circular dichroism in the ultraviolet range and emit in the visible green range The choice of this design is due to two reasons; firstly, proof-of-concept FDCD measurements of new solutions are experimentally easier in the visible range, and, secondly, we were led by the recent reports of chirality in nanostructured substrates in the visible range [29,30], which have potential for coupling with emitting molecules in future. We believe that the reported FDCD signals of these compounds can be further investigated via coupling with plasmonic nanostructures, opening new pathways toward enhanced chiral sensing applications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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.
