Electrochemical investigations of heteroarylethylene class and of related conducting films

Well-known simple molecules such as diphenylethylene (DPE), dithienylethylene (DTE), and tetraphenylethylene (TPE) show interesting optical properties; for instance, TPE has been extensively studied because of its tunable luminescent properties and some of its derivatives show aggregation-induced emission (AIE). The corresponding thiophene based system: tetra-(2-thienyl)-ethylene (TTE), also giving AIE, has not been as widely studied as TPE, but it and the peculiar electronic properties of the thiophene ring make it much more appealing than TPE for applications in photovoltaics and optoelectronics, both in itself and as building block in wider -conjugated systems. Moreover, regioselective functionalization of the thiophene rings in TTE could afford a wide target-oriented modulation of the scaffold properties. A few TTE derivatives had been reported, but no systematic investigation of the structural and electronic features of the thienylethylene class was available. Extension of the study to other heteroaromatic rings, such as the furane based ones, was also overdue. To fill these gaps, we have performed an electrochemical study, supported by spectroscopic experiments, on the aryl- and heteroarylethylene molecules shown in Figure, most of them new, synthesized by us according to an advantageous synthetic pathway. [1] Our exhaustive investigation now affords a detailed rationalization of the redox properties and electrooligomerization ability in this promising class of organic semiconductors, to be exploited for target-oriented molecular design optimization. [1] A. Bolzoni, L.Viglianti, A. Bossi, P.R. Mussini, S. Cauteruccio, C. Baldoli, E. Licandro, Eur. J. Org. Chem. 2013, 33, 7489–7499