Synthesis and structural study of 3-anisyl-4-(4'-pyridyl(pyridinium)thieno[2,3-b]thienophenes

摘要

A new class of co-facially oriented donor-acceptor thienothiophene 2 and its ionic analog 3 have been synthesized to investigate the presence of through-space vs through-bond charge transfer interaction.The key step is the double Dieckman cyclization on the ketene dithioacetal-5.Comparative ~1H NMR spectral analysis of 2 and 3 suggests through-bond charge transfer between the pi-deficient pyridinium ring and pi-rich thienophene ring being the dominant interaction with the through-space charge transfer interaction in 3 making a relatively small contribution.The interpretation of UV-Visible data 2 and 3 also seem to support such a conclusion.