- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Encyclopedia of Spectroscopy and Spectrometry || Surface-Enhanced Raman Optical Activity (SEROA)
摘要： This review discusses research into the enhancement of the chiroptical spectroscopic technique of Raman optical activity (ROA) through plasmonic resonance effects. The sensitivity of ROA spectroscopy to molecular stereochemistry and conformational dynamics has led to its increasing use in biology and the pharmaceutical sciences. However, the relative weakness of the ROA scattering process, being typically three to five orders of magnitude lower than the parent Raman scattering, has limited its application to conditions of relatively high concentrations and data accumulation times. The potential solution to this limitation in ROA by using the surface plasmon resonances that give rise to surface-enhanced Raman scattering (SERS) in order to boost ROA spectral intensity has been recognized by many researchers. Frustratingly, reliable measurement of this new technique of surface-enhanced Raman optical activity (SEROA) proved challenging to accomplish. A previous review by Abdali and Blanch presented the challenges involved in attempts to measure SEROA, as well as early results. Since then, significant advances have been made in exploring the SEROA phenomenon, and the time is appropriate for an updated account of this work. In order to provide sufficient background for guiding readers into the underlying principles of, and challenges faced in, measuring SEROA, we begin with an introduction to ROA before progressing on to its plasmonically-enhanced form.
关键词： chiroptical spectroscopy,SEROA,ROA,plasmonic resonance,Surface-Enhanced Raman Optical Activity,Raman Optical Activity,SERS,surface-enhanced Raman scattering
更新于2025-09-23 15:21:21
-
Formation of enhanced opposite one-handed chiral fields in heterodimer-film nanostructures
摘要： Plasmonic chirality has attracted a lot of interests because it could result in dramatically increased chiroptical interactions and offer many potential applications in chiral molecules analysis, catalysis, and other nanotechnology. In particular, one-handed chiral field is required in many applications for the reason that molecules are generally distributed randomly in some region of structures. In this work, benefiting from the coupling effect and energy focusing effect, we propose a heterodimer-film nanostructure to achieve one-handed chiral fields under linearly polarized light illumination. The results indicate that there are just opposite one-handed chiral fields in different gaps of the heterodimer-film nanostructure. The volume averaged optical chirality in the gaps can reach 102 and the optical chirality of hot spots can reach 103, which has potential applications in chiral sensing and Raman optical activity.
关键词： heterodimer-film nanostructure,Raman optical activity,one-handed chiral fields,chiral sensing,Plasmonic chirality,optical chirality enhancement
更新于2025-09-10 09:29:36
-
Chiral Analysis || Raman Optical Activity
摘要： Raman optical activity (ROA) has many advantages over conventional Raman spectroscopy for investigation of chiral molecules, in general, and biological molecules, in particular, on account of their homochirality. Since it is a manifestation of vibrational optical activity [1], being complementary to vibrational circular dichroism (VCD), ROA is more sensitive to the 3D structures of chiral molecules through its dependence on their absolute handedness, which has led to its development as an incisive probe of the structure and behavior of biomolecules in aqueous solution. For example, ROA spectra obtained from proteins can provide detailed information on the secondary and tertiary structures adopted by polypeptide backbones. Additionally, ROA can probe the tautomers of side chains. In common with other vibrational spectroscopies, there is no restriction on the size of molecules, or in their type, that can be investigated by ROA, broadening its application to unfolded proteins, viruses, and carbohydrates.
关键词： vibrational circular dichroism,proteins,Raman optical activity,aqueous solution,carbohydrates,vibrational optical activity,biological molecules,biomolecules,viruses,chiral molecules
更新于2025-09-09 09:28:46
-
Chiral Analysis || Vibrational Optical Activity in Chiral Analysis
摘要： Chiral analysis encompasses all analytical techniques focused on quantitative measures of the chiral properties of molecules. The properties unique to chiral molecules are absolute configuration (AC) and enantiomeric excess (ee). As will be discussed below, vibrational optical activity (VOA) can provide information on samples of chiral molecules by direct spectroscopic investigation without modifying the molecules by reacting them, sometimes irreversibly, with other chiral molecules or substrates. From a molecular point of view, VOA chiral analysis may be regarded as noninvasive in that the molecule is not changed or altered from its natural solution or solid-state condition in order to carry out the analysis. An important property of VOA is its sensitivity to the conformational states of chiral molecules, both in solution and in the solid state. Apart from the determination of the absolute chirality of a molecule, VOA can be used to specify these states, in conjunction with quantum mechanical calculations, and determine populations of solution-state conformers that are interconverting faster than the nuclear magnetic resonance (NMR) timescale. VOA can also be used to probe the solid-state conformations of chiral molecules as well as their polymorphic crystal forms. Although this information is not strictly chiral in nature, VOA has extraordinary sensitivity to both the absolute structure and the conformation of chiral molecules and this aspect of chiral analysis by VOA should not be overlooked.
关键词： absolute configuration (AC),Raman optical activity (ROA),enantiomeric excess (ee),Chiral analysis,vibrational optical activity (VOA),vibrational circular dichroism (VCD)
更新于2025-09-09 09:28:46
-
Absolute Configurations of Naturally Occurring [5]- and [3]-Ladderanoic Acids: Isolation, Chiroptical Spectroscopy, and Crystallography
摘要： We have isolated mixtures of [5]- and [3]-ladderanoic acids 1a and 2a from the biomass of an anammox bioreactor and have separated the acids and their phenacyl esters for the first time by HPLC. The absolute configurations of the naturally occurring acids and their phenacyl esters are assigned as R at the site of side-chain attachment by comparison of experimental specific rotations with corresponding values predicted using quantum chemical (QC) methods. The absolute configurations for 1a and 2a were independently verified by comparison of experimental Raman optical activity spectra with corresponding spectra predicted using QC methods. The configurational assignments of 1a and 2a and of the phenacyl ester of 1a were also confirmed by X-ray crystallography.
关键词： absolute configurations,quantum chemical methods,Raman optical activity,X-ray crystallography,ladderanoic acids,HPLC,anammox bioreactor
更新于2025-09-04 15:30:14