Carbonyl-functionalized quaterthiophenes: A study of the vibrational raman and electronic absorption/emission properties guided by theoretical calculations

Juan Aragõ, Ortizâ Ponce Ortizâ, Belén Nieto-Ortega, Víctor Hernández, Juan Casado, Antonio Facchetti, Tobin J Marks, Pedro M. Viruela, Enrique Ortí, Juan T. Lõpez Navarrete

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

This work investigates the evolution of the molecular, vibrational, and optical properties within a family of carbonyl-functionalized quaterthiophenes: 5,5″-diheptanoyl-2,2:5,2″:5″,2″-quaterthiophene (1), 5,5″-diperfluorohexylcarbonyl-2,2:5,2″:5″,2″- quaterthiophene (2), and 2,7-[bis(5-perfluorohexylcarbonylthien-2-yl)]-4H- cyclopenta[2,1-b:3,4-b]-dithiophene-4-one (3). The analysis is performed by Raman and UV/Vis absorption/excitation/fluorescence spectroscopy in combination with density functional calculations. Theoretical calculations show that substitution with carbonyl groups and perfluorohexyl chains induces progressive quinoidization of the π-conjugated backbone in comparison to the carbonyl-free compound 5,5″-dimethyl-2,2:5,2″:5″,2″- quaterthiophene (DM-4T) used as reference. Raman spectra are dominated by a strong Raman line which mainly corresponds to a combination of C-C/C=C stretching vibrations spreading over the whole thiophene core. This band undergoes a remarkable downshift as a consequence of the structural changes induced by the electron-withdrawing groups on the π-conjugated backbone. The band splitting on incorporation of a central carbonyl bridge evidences the formation of two structural domains in the molecule. The excitation and fluorescence spectra recorded at low temperature show well-resolved vibronic structures associated with the most intense collective C-C/C=C stretching mode. Optical absorption and fluorescence bands exhibit remarkable bathochromic dispersion on carbonyl functionalization, indicative of extension of π conjugation. TDDFT calculations enable a detailed description of the trends observed in the absorption spectra. Resonance Raman spectra reflect the structural changes predicted for the S 0S 1 electronic transition and evidence the cross-conjugated character that the central carbonyl group confers on 3.

Original languageEnglish
Pages (from-to)168-176
Number of pages9
JournalChemPhysChem
Volume13
Issue number1
DOIs
Publication statusPublished - Jan 16 2012

Fingerprint

Stretching
Raman scattering
Fluorescence
Thiophenes
fluorescence
Fluorescence spectroscopy
electronics
Light absorption
Raman spectra
Density functional theory
absorption spectra
Absorption spectra
Substitution reactions
Optical properties
molecular properties
thiophenes
conjugation
Molecules
excitation
Electrons

Keywords

  • carbonyl functionalization
  • density functional calculations
  • quaterthiophenes
  • Raman spectroscopy
  • UV/Vis spectroscopy

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Atomic and Molecular Physics, and Optics

Cite this

Aragõ, J., Ponce Ortizâ, O., Nieto-Ortega, B., Hernández, V., Casado, J., Facchetti, A., ... Lõpez Navarrete, J. T. (2012). Carbonyl-functionalized quaterthiophenes: A study of the vibrational raman and electronic absorption/emission properties guided by theoretical calculations. ChemPhysChem, 13(1), 168-176. https://doi.org/10.1002/cphc.201100736

Carbonyl-functionalized quaterthiophenes : A study of the vibrational raman and electronic absorption/emission properties guided by theoretical calculations. / Aragõ, Juan; Ponce Ortizâ, Ortizâ; Nieto-Ortega, Belén; Hernández, Víctor; Casado, Juan; Facchetti, Antonio; Marks, Tobin J; Viruela, Pedro M.; Ortí, Enrique; Lõpez Navarrete, Juan T.

In: ChemPhysChem, Vol. 13, No. 1, 16.01.2012, p. 168-176.

Research output: Contribution to journalArticle

Aragõ, J, Ponce Ortizâ, O, Nieto-Ortega, B, Hernández, V, Casado, J, Facchetti, A, Marks, TJ, Viruela, PM, Ortí, E & Lõpez Navarrete, JT 2012, 'Carbonyl-functionalized quaterthiophenes: A study of the vibrational raman and electronic absorption/emission properties guided by theoretical calculations', ChemPhysChem, vol. 13, no. 1, pp. 168-176. https://doi.org/10.1002/cphc.201100736
Aragõ, Juan ; Ponce Ortizâ, Ortizâ ; Nieto-Ortega, Belén ; Hernández, Víctor ; Casado, Juan ; Facchetti, Antonio ; Marks, Tobin J ; Viruela, Pedro M. ; Ortí, Enrique ; Lõpez Navarrete, Juan T. / Carbonyl-functionalized quaterthiophenes : A study of the vibrational raman and electronic absorption/emission properties guided by theoretical calculations. In: ChemPhysChem. 2012 ; Vol. 13, No. 1. pp. 168-176.
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