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oai:riuma.uma.es:10630/243632026-02-03T11:17:03Zcom_10630_2254col_10630_37953

Dai, Yasi Bonometti, Laura Zafra-Paredes, Jose Luis Takimiya, Kazuo Casado-Cordón, Juan Negri, Fabrizia 2022-06-14T11:22:36Z 2022-06-14T11:22:36Z 2022-04-15 Dai Y, Bonometti L, Zafra JL, Takimiya K, Casado J, Negri F. Raman Activities of Cyano-Ester Quinoidal Oligothiophenes Reveal Their Diradical Character and the Proximity of the Low-Lying Double Exciton State. Chemistry. 2022; 4(2):329-344. https://doi.org/10.3390/chemistry4020025 https://hdl.handle.net/10630/24363 10.3390/chemistry4020025 Quinoidal oligothiophenes have received considerable attention as interesting platforms with remarkable amphoteric redox behavior associated with their diradical character increasing with the conjugation lengths. In this work, we considered a family of quinoidal oligothiophenes bearing cyano-ester terminal groups and characterized them by UV-Vis-NIR absorption and Raman spectroscopy measurements at different excitation wavelengths. The experimental investigation is complemented by quantum-chemical studies to assess the quality of computed density functional theory (DFT) ground state structures and their influence on predicted Raman intensities. In addition, resonance conditions with the optically active HOMO→LUMO transition as well as with the more elusive state dominated by the doubly excited HOMO,HOMO→LUMO,LUMO configuration, are determined with DFT-MRCI calculations and their contributions to Raman activity enhancement are discussed in terms of computed vibrational Huang–Rhys (HR) factors eng http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional Espectroscopía Raman Raman Activities of Cyano-Ester Quinoidal Oligothiophenes Reveal Their Diradical Character and the Proximity of the Low-Lying Double Exciton State journal article