1418000-98-2Relevant academic research and scientific papers
Switching of emissive and NLO properties in push-pull chromophores with crescent PPV-like structures
Coluccini, Carmine,Sharma, Arvind K.,Caricato, Marco,Sironi, Angelo,Cariati, Elena,Righetto, Stefania,Tordin, Elisa,Botta, Chiara,Forni, Alessandra,Pasini, Dario
, p. 1666 - 1674 (2013/03/13)
We report on a series of novel homologous push-pull compounds, in which identical donor (a dimethylamino) and acceptor (a malonate ester) functionalities endcap crescent PPV fragments, bearing, respectively, 1, 2 and 3 p-phenylenevinylene units in direct linear conjugation (compounds 7-9). The three compounds exhibit striking differences in their linear and nonlinear optical properties. The shorter compound 7 exhibits aggregation-induced emission with a strong luminescence in the solid state (blue emission, photoluminescence quantum yield 38%), and it is nonemissive in solution; the more extended conjugated systems 8 and 9 show classical aggregation-caused quenching in the solid state, while high quantum yield photoluminescence (21 and 93% in toluene) is restored in diluted solutions, through mechanisms involving intramolecular charge transfer in the excited states. EFISH measurements in solutions demonstrate a strong solvent and concentration dependence. As rationalized with the aid of molecular modelling, compounds 8 and, more markedly, 9 aggregate in stable centrosymmetric dimers in solution.
