Synthesis of penta- and hexa(3,4-thienylene): size-dependent structural properties of cyclic oligothiophenes

Penta- and hexa(3,4-thienylene)s were synthesized as a potential precursor for thiophene-containing polyarenes, and the structures were determined via X-ray crystallography. The interconversion of thiophene rings is fast in penta(3,4-thienylene), and slow in hexa(3,4-thienylene) reflecting the activation energy for enantiomerization. Size-dependent bathochromic shifts were observed in UV-vis absorption spectra. Penta- and hexa(3,4-thienylene)s were synthesized and their nonplanar macrocyclic structures were determined by X-ray crystallography. NMR spectroscopy and theoretical calculation revealed size-dependent isomerization behavior.

Automated summary

Penta- and hexa(3,4-thienylene)s were synthesized as potential precursors for thiophene-containing polyarenes, and their structures were determined via X-ray crystallography. The interconversion of thiophene rings was found to be fast in penta(3,4-thienylene) and slow in hexa(3,4-thienylene), indicating different activation energies for enantiomerization. Size-dependent bathochromic shifts were observed in the UV-vis absorption spectra.