Diradical Character of Benzo- and Naphtho-Annelated Thiophene-Pyrrole Mixed Oligomer Dications

作者：Kageyama Takuya; Uneme Shunsuke; Takase Masayoshi; Nomura Kotohiro; Nishinaga Tohru^*

来源：Australian Journal of Chemistry, 2014, 67(5): 722-728.

DOI：10.1071/CH13522

Benzo- and naphtho-annelated thiophene-pyrrole mixed octamers Bz8TP-C-m and Np8TP-C-m, comprising benzo- or naphthodithiophene and two dithienylpyrrole units, were synthesised. Density functional theory (DFT) calculations based on B3LYP/6-31G(d) with the broken symmetry method predicted that dications Bz8TP-C-1(2+) and Np8TP-C-1(2+) have stronger diradical character than previously investigated non-annelated thiophene-pyrrole mixed octamer 8TP-C-1(2+) (R-1 = R-2 = H). Compounds Bz8TP-C-8 and Np8TP-C-8 showed a one-step, two-electron oxidation process based on cyclic voltammetry analysis. Reaction with SbCl5 involved a two-electron oxidation. Bz8TP-C-8(2+) and Np8TP-C-8(2+) displayed similar absorption spectra to that of nonamer 9TP-C-12(2+) (R-1 = R-2 = H), rather than that of octamer 8TP-C-12(2+), indicating the stronger diradical characters of octamers Bz8TP-C-8(2+) and Np8TP-C-8(2+), as enhanced by benzo- and naphtho-annelation, and were comparable with that of 9TP-C-12(2+). Time-dependent-DFT calculations supported the conclusion obtained from the experimental results.

• 出版日期2014