Quinoidal Oligothiophenes: Towards Biradical Ground-State Species

被引：77

作者：

Ponce Ortiz, Rocio ^{[1
]}

Casado, Juan ^{[1
]}

Rodriguez Gonzalez, Sandra ^{[1
]}

Hernandez, Victor ^{[1
]}

Lopez Navarrete, Juan T. ^{[1
]}

Viruela, Pedro M. ^{[2
]}

Orti, Enrique ^{[2
]}

Takimiya, Kazuo ^{[3
]}

Otsubo, Tetsuo ^{[3
]}

机构：

[1] Univ Malaga, Dept Quim Fis, E-29071 Malaga, Spain

[2] Univ Valencia, Inst Ciencia Mol, Valencia 46071, Spain

[3] Hiroshima Univ, Dept Appl Chem, Higashihiroshima 7398527, Japan

来源：

CHEMISTRY-A EUROPEAN JOURNAL | 2010年 / 16卷 / 02期

关键词：

biradicals; density functional calculations; electronic structure; oligothiophenes; vibrational spectroscopy; END-CAPPED OLIGOTHIOPHENES; DENSITY-FUNCTIONAL THEORY; TERTHIOPHENE-BASED QUINODIMETHANE; ELECTRONIC-ABSORPTION-SPECTRA; HEAD-TO-HEAD; HARTREE-FOCK; CHARGE-TRANSFER; RAMAN-SPECTRA; HETEROQUINONOID SYSTEM; CONDUCTIVE COMPLEXES;

D O I：

10.1002/chem.200902037

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

A family of quinoidal oligothiophenes, from the dimer to the hexamer, with fused bis(butoxymethyl)cyclopentane groups has been extensively investigated by means of electronic and vibrational spectroscopy, electrochemical measurements, and density functional Calculations. The latter predict that the electronic ground state always corresponds to a singlet state and that, for the longest oligomers, this state has biradical character that increases with increasing oligomer length. The shortest oligomers display closed-shell quinoidal structures. Calculations also predict the existence of very low energy excited triplet states that can be populated at room temperature. Aromatization of the conjugated carbon backbone is the driving force that determines the increasing biradical character of the ground state and the appearance of low-lying triplet states. UV/Vis, Raman, IR, and electrochemical experiments support the aromatic biradical structures predicted for the ground state of the longest oligomers and reveal that population of the low-lying triplet state accounts for the magnetic activity displayed by these compounds.

引用

页码：470 / 484

页数：15

共 72 条

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