Conjugated ladder polymers containing thienylene units

The general synthetic procedure of ladder-type poly(para-phenylene)-type ribbon (LPPP) involves the generation of a suitably functionalized, single stranded PPP precursor and its polymer-analogous cyclization including a Friedel-Crafts type alkylation reaction as key step. One of the ladder polymers, an all-thienylene-based ladder structure is soluble in methylene chloride and exhibits an UV-vis spectrum with a steep absorption edge and well resolved vibronic fine structure which is characteristic of planar and defect free 1D π-system. The application of the methodology toward phenylene-type aromatic LPPP for the generation of related heteroarylene ladder polymers containing 2,5-thienylene units is discussed.