Tetrahedral Oligothiophenes; Synthesis, X‐ray Analysis, and Optoelectronic Properties of Highly Symmetrical, 3D‐Branched Oligothiophenes

• Published in: Chemistry, an Asian journal an Asian journal, 2008-12, Vol.3 (12), p.2024-2032
• Main Authors: Matsumoto, Kouzou, Tanaka, Toru, Kugo, Sota, Inagaki, Takuya, Hirao, Yoshikazu, Kurata, Hiroyuki, Kawase, Takeshi, Kubo, Takashi
• Format: Article
• Language: English
• Subjects: density functional calculations; fluorescence spectroscopy; Suzuki–Miyaura coupling; UV/Vis spectroscopy; X‐ray diffraction
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.200800288

Tetrakis(bithienyl)methane and tetrakis(terthienyl)methane have been synthesized from tetrakis(2‐thienyl)methane by use of Suzuki–Miyaura coupling as a key reaction. Their trimethylsilyl (TMS) derivatives are also synthesized. X‐ray analysis reveals that each oligothiophene moiety tends to adopt anti‐conformations and show relatively small torsion angles between the adjacent thiophene rings. While the longest absorption maxima of these tetrakis(oligothienyl)methanes exhibit only a slight bathochromic shift compared to the corresponding linear oligothiophene derivative, tetrakis(bithienyl)methane and its TMS derivative exhibit an appreciable red‐shift in their fluorescence spectra. The intramolecular interaction between thienyl groups of tetrakis(2‐thienyl)methane is supported by DFT calculation. Highly symmetric oligothiophenes: A series of tetrakis(oligothienyl)methanes has been synthesized as novel type of 3D‐branched oligothiophene derivatives. Highly symmetric crystal structure is reflected by the high symmetric molecular structure. Intramolecular interaction between the oligothiophene moieties is suggested by UV/Vis and fluorescence spectroscopy as well as by DFT calculations.