"Genetically modified" spider-like oligothiophenes : electron properties and electropolymerization

Multithiophene-based semiconductors are a virtually boundless class of molecular functional materials with very promising potential applications in a variety of fields, like electronics, energetics, sensoristics. Starting from our previous exhaustive work on “spider-like” branched oligothiophenes, affording a reliable rationalization of the relationships between structure and electronic properties1,2, we have recently developed many structure modifications with respect to the original all-thiophene systems, aiming to achieve finer and wider modulation of both the HOMO and LUMO levels. In particular, the “core” of our oligothiophene systems has been modified by inserting appropriate building blocks of different electron richness, asymmetrically affecting both the LUMO and HOMO energy levels and localization along the main conjugated backbone, thus achieving one more freedom degree in tuning the electron properties of the molecule. A wide series of “genetically-modified” spider-like oligothiophenes and their electrodeposited conducting polymers have been investigated by CV and EIS, focusing on the effect of core modification at constant thiophene side chains, and on the effect of increasing length and/or branching in the thiophene side chains at constant modified core. The core modification appears to be much more effective on the HOMO and LUMO energy levels and positions, while effective conjugation in the thiophene side chains is more determining on the oligomerization ability. The exhaustiveness of our investigation affords interpretative and predictive criteria which could usefully exploited in target-oriented molecular design.