Spectroscopic and electrochemical properties of new amphiphilic donor–acceptor conjugated polyenes

New, terminally substituted, unsymmetrical conjugated polyenes ROC6H4(CHCH)nTB (TB = l,3-diethyl-thioxodihydropyrimidine-4,6-dione: R = CH3 (n = 4, 6); R = C6H13 (n = l, 2, 3, 4, 5, 6)) ROC6H4(CHCH)nID (ID = indan-l,3-dione: R = CH3, C6H13 (n = 4, 6)), and ROC6H4(CHCH)nPN (PN = phenylacetonitrile R = CH3, C6H13 (n = 4, 6)) were synthesized through Knoevenagel condensation of respective ω-(p-alkyloxyphenyl)polyenals and benzyl cyanide (A = PN), indandione (A = ID) and N,N′-diethylthiobarbituric acid (A = TB). These compounds show a remarkable thermal stability with decomposition temperatures ranging from 133 to 291 °C. For all obtained push-pull polyenes, the shift of λmax to longer wavelength was observed as a function of the increasing conjugated system size as well as the donor–acceptor (D–A) pair strength. The inverted solvatochromic effect appeared with the increase of solvent polarity. The redox properties of the studied compounds were investigated applying the cyclic voltammetry technique (CV). Electrochemically evaluated band gap values are well correlated with the optical data.