Quinoidal/Aromatic Transformations in π-Conjugated Oligomers: Vibrational Raman studies on the Limits of Rupture for π-Bonds

被引:96
作者
Mayorga Burrezo, Paula [1 ]
Zafra, Jose L. [1 ]
Lopez Navarrete, Juan T. [1 ]
Casado, Juan [1 ]
机构
[1] Univ Malaga, Dept Phys Chem, Andalucia Tech, Campus Teatinos S-N, E-29071 Malaga, Spain
关键词
aromaticity; conjugation; oligomers; radicals; raman spectroscopy; END-CAPPED OLIGOTHIOPHENES; SOLITONS; SPECTROSCOPY; POLYMERS; SPECTRA; DELOCALIZATION; POLYACETYLENE; SCATTERING; MOLECULES; ELECTRON;
D O I
10.1002/anie.201605893
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The vibrational Raman spectra of several series of aromatic and quinoidal compounds have been analyzed considering the downshifts and upshifts of the frequencies of the relevant Raman bands as a function of the number of repeating units. Oligothiophenes, oligophenylene-vinylenes, and oligoperylenes (oligophenyls) derivatives are studied in a common context. These shifts are taken as spectroscopic fingerprints of the changes in pi-conjugation. For a given family, aromatic and quinoidal oligomers have been studied together, and according to their Raman frequency shifts located in the two-well BLA-energy curve of their ground electronic state as a function of the bond-length-alternation pattern (BLA). The connection among BLA values, pi-conjugation, and Raman frequencies is taken here as the basis of the study. These Raman shifts/BLA changes have been related to important electronic properties of these one-dimensional linear pi-electron delocalized systems such as quinoidal (polyene) and aromatic characters.
引用
收藏
页码:2250 / 2259
页数:10
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