Circular dichroism: electronic

Abstract

First‐principles calculations of electronic circular dichroism (ECD) are widely used to determine absolute configurations of chiral molecules. In addition, ECD is a sensitive probe for the three‐dimensional molecular structure, making ECD calculations a useful tool to study conformational changes. In this review, we explain the origin of ECD and optical activity using response theory. While the quantum‐mechanical underpinnings of ECD have been known for a long time, efficient electronic structure methods for ECD calculations on molecules with more than 10–20 atoms have become widely available only in the past decade. We review the most popular methods for ECD calculation, focusing on time‐dependent density functional theory. Although single‐point vertical ECD calculations yield useful accuracy for conformationally rigid systems, inclusion of finite‐temperature effects is necessary for flexible molecules. The scope and limitations of modern ECD calculations are illustrated by applications to helicenes, fullerenes, iso‐schizozygane alkaloids, paracyclophanes, β‐lactams, and transition metal complexes. © 2011 John Wiley & Sons, Ltd. WIREs Comput Mol Sci 2011 00 1–17 DOI: 10.1002/wcms.55 This article is categorized under: Electronic Structure Theory > Density Functional Theory

An Enantiopure Propeller‐Like Trityl‐Brominated Radical: Bringing Together a High Racemization Barrier and an Efficient Circularly Polarized Luminescent Magnetic Emitter

“…AC) of the ( P )‐ and ( M )‐enantiomers. Conversely, a comparison between experimental ECD spectra with data from TD‐DFT calculations was carried out. Figure (central) portrays the calculated UB3LYP/6–311+G** ECD spectrum for the ( P ) ‐TTBrM radical, showing a reasonably good agreement found with the experimental ECD of the second eluted (CSP)HPLC fraction (see Section S8 of the Supporting Information for further details).…”

Good Computational Practice in the Assignment of Absolute Configurations by TDDFT Calculations of ECD Spectra

“…Not surprisingly, then, nonempirical methods of analysis such as the exciton chirality have become quickly popular and spurred much research . The revolution, or renaissance, of chiroptical spectroscopies, however, arrived when the ab initio theoretical simulation of chiroptical properties, including ECD, optical rotation (OR), vibrational CD (VCD), Raman optical activity (ROA), and so on, became a concrete possibility for real‐life molecules such as natural products and transition metal complexes . Quantum‐mechanical (QM) calculations of chiroptical spectra make it possible to assign AC's without the need for any reference system or any chemical derivatization, and often without the necessity of establishing the molecular physicochemical mechanisms responsible for the observed property (the so‐called mechanisms of optical activity).…”

Double-hybrid density functionals: merging wavefunction and density approaches to get the best of both worlds

“…Other recent applications, the (necessarily limited and biased) following selection tries only to show the wide and rich range of systems being currently afforded, include the modelling of ionic liquids [175], gas adsorption in metalorganic frameworks [176,177], isomerism in monosaccharides [178], conformational analysis [179,180], nonlinear optical responses [181], magnetic couplings in organometallics [182], enzymatic catalysis [183,184], electron paramagnetic resonance hyperfine coupling tensors [185], inclusion complexes and nanoencapsulation [186], electronic circular dichroism [187], organometallic complexes of graphene [188], interfacial chemistry [189], photosynthetic water oxidation [190], hyperpolarizability of pushpull systems [191], lightharvesting complexes [192], adsorbate-zeolite interactions [193], or harmonic and anharmonic vibrational frequency calculations [194], among others. • Figure 1.…”