Synthesis and characterization of 3‐hexyl multi‐substituted α,ω‐diformyl‐α‐oligothiophenes (n = 3, 6, 8)

The synthesis and characterization of a series of thienylenic α,ω‐diformyl‐α‐oligothiophenes with 3, 6 and 8 residues is reported. The chemical structure was determined by 1H NMR, FT‐IR, mass and GPC analyses, while the electronic properties in the neutral state were studied by UV‐Vis spectroscopy both in solution and in the solid state. In the UV‐Vis spectra of thin films, the vibronic structure is observed. The pronounced red‐shift of the absorption maximum, with respect to spectra of unsubstituted α‐oligothiophenes, is indicative of a contribution of carbonyl π‐electrons to the overall delocalization via a mesomeric effect leading to a more planar structure. The solid state aggregation was investigated by XRD spectroscopy and optical microscopy. We observed for the longest terms a smectic arrangement typical of liquid crystalline compounds and a tendency to self‐assembling onto hydrophilic substrates, forming angles ranging from 40–50° with respect to the normal to the surface.