New Insights on the Raman and SERS Spectra of Luteolin under Different Excitation Conditions: Experiments and DFT Calculations
We have studied, by density functional theory, the interaction between luteolin and Ag, devising two complexes where an Ag<sub>14</sub> cluster faces two different sites of the molecule. The two sites are identified as quinoid-like and cathecol-like, and the complexes are CPLX1 and CPLX2...
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MDPI AG
2023-02-01
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| Series: | Chemosensors |
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| Online Access: | https://www.mdpi.com/2227-9040/11/2/104 |
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| author | Marilena Ricci Emilio Mario Castellucci Silvia Innocenti Maurizio Becucci |
| author_facet | Marilena Ricci Emilio Mario Castellucci Silvia Innocenti Maurizio Becucci |
| author_sort | Marilena Ricci |
| collection | DOAJ |
| description | We have studied, by density functional theory, the interaction between luteolin and Ag, devising two complexes where an Ag<sub>14</sub> cluster faces two different sites of the molecule. The two sites are identified as quinoid-like and cathecol-like, and the complexes are CPLX1 and CPLX2, respectively. Raman and SERS spectra of luteolin were measured at different excitation wavelengths. Luteolin solid samples from different suppliers have different Raman spectra, possibly associated with different arrangements in the solids. These spectra are well reproduced by our DFT calculations. Assignment of the vibrational modes of luteolin and of the two luteolin–Ag<sub>14</sub> complexes is obtained thanks to decomposition of the normal coordinates in terms of internal coordinates. The calculated Raman spectrum for CPLX1 seems to better reproduce the experimental SERS spectra. CPLX2 furnishes a spectrum still resembling that of luteolin in the high frequency region and is possibly responsible for some weak bands in the 1400–1700 cm<sup>−1</sup> range that cannot be accounted by the CPLX1 system. SERS spectra are dependent on the Raman excitation wavelength. The calculation of the electronic spectrum suggests the presence of charge-transfer states, which might be responsible for the changes in the SERS spectra. |
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| id | doaj.art-9d2c2824fa554e16b82404b49d190dae |
| institution | Directory Open Access Journal |
| issn | 2227-9040 |
| language | English |
| last_indexed | 2024-03-11T09:00:07Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
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| series | Chemosensors |
| spelling | doaj.art-9d2c2824fa554e16b82404b49d190dae2023-11-16T19:46:19ZengMDPI AGChemosensors2227-90402023-02-0111210410.3390/chemosensors11020104New Insights on the Raman and SERS Spectra of Luteolin under Different Excitation Conditions: Experiments and DFT CalculationsMarilena Ricci0Emilio Mario Castellucci1Silvia Innocenti2Maurizio Becucci3Department of Chemistry ‘Ugo Schiff’, University of Florence, via della Lastruccia 3-13, 50019 Sesto Fiorentino, ItalyEuropean Laboratory for Non Linear Spectroscopy (LENS), University of Florence, via N. Carrara 1, 50019 Sesto Fiorentino, ItalyCNR-INO National Research Council, National Institute of Optics, Largo E. Fermi 6, 50125 Florence, ItalyDepartment of Chemistry ‘Ugo Schiff’, University of Florence, via della Lastruccia 3-13, 50019 Sesto Fiorentino, ItalyWe have studied, by density functional theory, the interaction between luteolin and Ag, devising two complexes where an Ag<sub>14</sub> cluster faces two different sites of the molecule. The two sites are identified as quinoid-like and cathecol-like, and the complexes are CPLX1 and CPLX2, respectively. Raman and SERS spectra of luteolin were measured at different excitation wavelengths. Luteolin solid samples from different suppliers have different Raman spectra, possibly associated with different arrangements in the solids. These spectra are well reproduced by our DFT calculations. Assignment of the vibrational modes of luteolin and of the two luteolin–Ag<sub>14</sub> complexes is obtained thanks to decomposition of the normal coordinates in terms of internal coordinates. The calculated Raman spectrum for CPLX1 seems to better reproduce the experimental SERS spectra. CPLX2 furnishes a spectrum still resembling that of luteolin in the high frequency region and is possibly responsible for some weak bands in the 1400–1700 cm<sup>−1</sup> range that cannot be accounted by the CPLX1 system. SERS spectra are dependent on the Raman excitation wavelength. The calculation of the electronic spectrum suggests the presence of charge-transfer states, which might be responsible for the changes in the SERS spectra.https://www.mdpi.com/2227-9040/11/2/104flavonoidluteolinRamanSERSAg-clustersDFT |
| spellingShingle | Marilena Ricci Emilio Mario Castellucci Silvia Innocenti Maurizio Becucci New Insights on the Raman and SERS Spectra of Luteolin under Different Excitation Conditions: Experiments and DFT Calculations Chemosensors flavonoid luteolin Raman SERS Ag-clusters DFT |
| title | New Insights on the Raman and SERS Spectra of Luteolin under Different Excitation Conditions: Experiments and DFT Calculations |
| title_full | New Insights on the Raman and SERS Spectra of Luteolin under Different Excitation Conditions: Experiments and DFT Calculations |
| title_fullStr | New Insights on the Raman and SERS Spectra of Luteolin under Different Excitation Conditions: Experiments and DFT Calculations |
| title_full_unstemmed | New Insights on the Raman and SERS Spectra of Luteolin under Different Excitation Conditions: Experiments and DFT Calculations |
| title_short | New Insights on the Raman and SERS Spectra of Luteolin under Different Excitation Conditions: Experiments and DFT Calculations |
| title_sort | new insights on the raman and sers spectra of luteolin under different excitation conditions experiments and dft calculations |
| topic | flavonoid luteolin Raman SERS Ag-clusters DFT |
| url | https://www.mdpi.com/2227-9040/11/2/104 |
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