TY - JOUR
T1 - Toward the rational design of conjugated oligomers and polymers
T2 - Systematic study of the substituent effect in oligothiophenes
AU - Zamoshchik, Natalia
AU - Sheynin, Yana
AU - Bendikov, Michael
PY - 2014/6
Y1 - 2014/6
N2 - A systematic study of substituent electronic effects on a number of oligothiophene properties was performed using well-defined oligothiophenes of various chain lengths that were monosubstituted with classical electron-withdrawing or -donating groups. The main focus was to understand how the effect of a substituent on one thiophene ring was transmitted through the other thiophene rings in the oligomer. The physical and electrochemical properties were studied by optical absorption and emission spectroscopy and by cyclic voltammetry. The experimental data were complemented with theoretical calculations of HOMO-LUMO gaps, charge distribution, bond length alternations, and 13C NMR spectra. We show that substitution has a significant electronic effect on the substituted ring; however, the effect decreases strongly over conjugation. A semiquantitative evaluation of the substituent effect in a well-defined long conjugated system was obtained for the first time using the Hammett equation.
AB - A systematic study of substituent electronic effects on a number of oligothiophene properties was performed using well-defined oligothiophenes of various chain lengths that were monosubstituted with classical electron-withdrawing or -donating groups. The main focus was to understand how the effect of a substituent on one thiophene ring was transmitted through the other thiophene rings in the oligomer. The physical and electrochemical properties were studied by optical absorption and emission spectroscopy and by cyclic voltammetry. The experimental data were complemented with theoretical calculations of HOMO-LUMO gaps, charge distribution, bond length alternations, and 13C NMR spectra. We show that substitution has a significant electronic effect on the substituted ring; however, the effect decreases strongly over conjugation. A semiquantitative evaluation of the substituent effect in a well-defined long conjugated system was obtained for the first time using the Hammett equation.
KW - density functional calculations
KW - electrochemistry
KW - oligomers
KW - polymers
KW - substituent effects
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U2 - 10.1002/ijch.201400010
DO - 10.1002/ijch.201400010
M3 - Article
AN - SCOPUS:84903266445
VL - 54
SP - 723
EP - 735
JO - Israel Journal of Chemistry
JF - Israel Journal of Chemistry
SN - 0021-2148
IS - 5-6
ER -