Star-Shaped Oligothiophenes Containing an Isotruxene Core: Synthesis, Electronic Properties, Electropolymerization, and Film Morphology

The synthesis, photophysical and electrochemical properties, and OFT calculations of four star-shaped pi-conjugated systems (ITTn, n = 1-4) consisting of an isotruxene (IT) core and three alpha-oligothiophene (OT) arms of 1-4 hexylthiophene rings (T1-T4) are reported. The electronic properties, spectroelectrochemistry, and AFM images of the electrodeposited polymer films of ITTn on ITO electrodes (i.e., poly(ITTn)) are also presented. As the OT length (i.e., the n value) increases, the electronic spectra are red-shifted, the fluorescence quantum yields are reduced, the first oxidation potentials are negatively shifted, the surface roughness of the polymer films is increased, and the formation of bipolaron dopants in the polymer becomes more favorable. The strong electronic couplings among the three OT arms render ITTn and poly(ITTn) a new class of two-dimensional pi-conjugated oligomers and polymers.