Vibrational Circular Dichroism of Thiolate-Protected Au25 Clusters: Accurate Prediction of Spectra and Chirality Transfer within the Mixed Ligand Shell
| Autor: | Wybren Jan Buma, Thomas Bürgi, Valentin P. Nicu, Raymond Azoulay, Annelies Sels, Mark A. J. Koenis |
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| Přispěvatelé: | Molecular Spectroscopy (HIMS, FNWI) |
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Chemistry
Ligand Shell (structure) 02 engineering and technology Mixed ligand 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Spectral line 3. Good health 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Crystallography General Energy Vibrational circular dichroism ddc:540 Physical and Theoretical Chemistry 0210 nano-technology Chirality (chemistry) |
| Zdroj: | Journal of Physical Chemistry C, 123(36), 22586-22594. American Chemical Society Journal of Physical Chemistry. C, Vol. 123, No 36 (2019) pp. 22586-22594 |
| ISSN: | 1932-7447 |
| Popis: | We have prepared Au25(PET)18-2x((R)-FBI-NAS)x(PET = 2-phenylethylthiol, (R)-FBINAS = (R)-5,5',6,6',7,7',8,8'-octafluoro-[1,1'-binaphthalene]-2,2'-dithiol) mixed ligand shell clusters via ligand exchange. Two fractions with different composition of the ligand shell were separated using size-exclusion chromatography and studied by infrared (IR) spectroscopy and vibrational circular dichroism (VCD). Both IR and VCD spectra are dominated by FBINAS vibrations although PET is more abundant on the cluster. Calculated VCD spectra on a model cluster Au25(SH)16(FBINAS)1 depend on the charge state of the cluster, and the anion is in excellent agreement with the experimental spectra of the Au25(PET)18-2x(FBINAS)x samples. Calculations of Au25(SH)14(FBINAS)2 furthermore show very similar spectra for different adsorption isomers with one exception, where the two ligands share a SR-Au-SR-Au-SR staple motif. Model calculations show that it is not necessary to consider the entire cluster for obtaining reliable VCD and IR spectra, but the staple motifs cannot be neglected. A band that is assigned to PET shows significant vibrational optical activity, and an anisotropy factor that depends on the composition of the ligand shell. This shows that the FBINAS molecules can transfer chirality to achiral PET within the ligand shell of the cluster. |
| Databáze: | OpenAIRE |
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