Kreß, K.C.K.C.KreßFischer, T.T.FischerStumpe, J.J.StumpeFrey, W.W.FreyRaith, M.M.RaithBeiraghi, O.O.BeiraghiEichhorn, S.H.S.H.EichhornTussetschläger, S.S.TussetschlägerLaschat, S.S.Laschat2022-03-042022-03-042014https://publica.fraunhofer.de/handle/publica/23697310.1002/cplu.2013003082-s2.0-84893958181Three series of rigidified tri-, penta- and heptamethine merocyanine dyes were synthesised. A piperidyl moiety was chosen as the electron-donating substituent while the electron-accepting group was varied from ketones to malononitriles and cyanoacetates. The structures of the compounds in the solid state and in solution were elucidated by X-ray diffraction and NMR spectroscopy, respectively, while optical properties were investigated by absorption and emission spectroscopy. As a general trend, the acceptor properties decrease in the series malononitrile>cyanoacetate>ketone based on the analysis of their solvatochromic behaviour. The experimental results were further supported by calculations at the B3LYP 6-311+G(d) level of theory.enjournal article