Synthesis and Properties of a Series of the Longest Oligothiophenes up to the 48-mer

Abstract

A series of the longest class of oligothiophenes extended at intervals of seven thiophene units from the 6-mer up to the 48-mer has been synthesized by a combination of the random Eglinton coupling reaction of mono- and di-ethynylsexithiophenes and a subsequent sodium sulfide-induced cyclization reaction of the resulting oligo(sexithienylene-diethynylene)s. Their structures were well characterized by MALDI-TOF MS and 1H NMR spectroscopy. The molecular weights of the oligothiophenes and oligo(sexithienylene-diethynylene)s, measured by gel-permeation liquid chromatography using the polystyrene standard, are nearly double the actual ones, indicating that they keep highly rigid rod-type shapes. According to a molecular model, the molecular lengths of the longest oligothiophene 48-mer and the longest oligo(sexithienylene-diethynylene) reach approximately 18.6 nm and 25.0 nm, respectively. In the electronic absorption and emission spectra, the π–π* transitions of the oligothiophenes demonstrate progressive red shifts with increasing chain length up to the 20-mer. In the cyclic voltammograms, furthermore, the first oxidation potentials tend to continue negative shifts up to the 34-mer. In accordance with these spectral changes, the doped conductivities steadily increase and approach that of a structurally related polymer.

Intrachain photoluminescence dynamics of a long oligothiophene at room temperature

“…In this regard, long-sized conjugated oligomers with definite chain length are ideal compounds for the research. In reality, the use of such oligomers has been shown to be effective for the research of conjugated polymers [3][4][5][6][7][8][9][10].…”

Dynamic force microscopy and X-ray photoemission spectroscopy studies of nanowire fabrication on a highly oriented line-structure of Al surface

“…Conducting polymers with conjugate system are supposed to be prospective for nanowire fabrication because of variety of monomer selectivity and of side chain selectivity such as oligomers, oligothiophene, and porphyrin [1,2,3,4]. Organic nanowires have been chemically synthesized.…”

Supuramolecular Structure of Self-assembly Fabricated with Novel Aromatic Polyether on Si-wafers

“…However, these synthetic polymers have a wide distribution in the degree of polymerization, so that it is very difficult to get a synthetic polymer with a specific or unique function, in comparison to biological polymers. Lenze et al proposed the chain polymerization method based on the living radical process as a novel polymerization method [8][9][10][11][12] . This new synthetic method was further improved by Lazano et al [13][14][15][16][17] .…”