Systematic study on the TD-DFT calculated electronic circular dichroism spectra of chiral aromatic nitro compounds: A comparison of B3LYP and CAM-B3LYP
| Autor: | József Nagy, Balázs Komjáti, Benjámin Kováts, Peter Horvath, Ákos Urai, József Kökösi, Sándor Hosztafi |
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| Rok vydání: | 2015 |
| Předmět: |
Circular dichroism
education.field_of_study 010304 chemical physics Chemistry Population 010402 general chemistry 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences Analytical Chemistry Atomic orbital Computational chemistry Excited state 0103 physical sciences Nitro Molecule Density functional theory education Instrumentation Spectroscopy Basis set |
| Zdroj: | Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy. 155 |
| ISSN: | 1873-3557 |
| Popis: | B3LYP is one of the most widely used functional for the prediction of electronic circular dichroism spectra, however if the studied molecule contains aromatic nitro group computations may fail to produce reliable results. A test set of molecules of known stereochemistry were synthesized to study this phenomenon in detail. Spectra were computed by B3LYP and CAM-B3LYP functionals with 6-311++G(2d,2p) basis set. It was found that the range separated CAM-B3LYP gives better predictions than B3LYP for all test molecules. Fragment population analysis revealed that the nitro groups form highly localized molecule orbitals but the exact composition depends on the functional. CAM-B3LYP allows sufficient spatial overlap between the nitro group and distant parts of the molecule, which is necessary for the accurate description of excited states especially for charge transfer states. This phenomenon and the synthesized test molecules can be used to benchmark theoretical methods as well as to help the development of new functionals intended for spectroscopical studies. |
| Databáze: | OpenAIRE |
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