Terpyridine derivatives functionalized with (hetero)aromatic groups and the corresponding Ru complexes: synthesis and characterization as SHG chromophores

• Autor(a) principal: Fernandes, Sara Sofia Marques
• Data de Publicação: 2018
• Outros Autores: Belsley, M., Ciarrocchi, Carlo, Licchelli, Maurizio, Raposo, M. Manuela M.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/1822/49648
• topic: Synthesis; Terpyridine; Push-pull heterocyclic systems; Ruthenium complexes; Second-harmonic generators (SHG); Nonlinear optics (NLO); Heterocycles; Ligands; UV-visible spectroscopy; Electrochemistry; Push-pull heterocyclic ligands; Ciências Naturais::Ciências Químicas; Science & Technology

Push–pull terpyridine derivatives were synthesized and characterized in order to study the variations produced in their optical and electronic properties by linking different (hetero)aromatic electron donor moieties at position 4 of the electron deficient terpyridine moiety. The final donor-acceptor systems were synthesized in fair to good yields by Kröhnke condensation of the precursor aldehydes, with 2-acetylpyridine. Hyper-Rayleigh scattering in dioxane solutions using a fundamental wavelength of 1064 nm was employed to evaluate their second-order nonlinear optical properties. Terpyridine derivative functionalized with the 9-ethyl-9H-carbazolyl group exhibited the largest first hyperpolarizability (beta = 610 × 10-30 esu, using the T convention) thus indicating its potential application as a second harmonic generation (SHG) chromophore. Terpyridine derivatives were also used as ligands for the synthesis of novel [RuII(tpy)(NCS)3]– complexes, prepared in good yields by a two-step procedure involving the preparation of [RuIII(tpy)(Cl3] as precursors. RutheniumII complexes display a broad absorption in the visible range, accounting for their very dark color. Their redox behaviour is mainly characterized by the RuII-RuIII oxidation and by the ligand-centred reduction, whose potentials can be finely tuned by the electronic properties of the aromatic substituents on the terpyridine ligand. Hyper-Rayleigh scattering in methanol solutions using a fundamental wavelength of 1064 nm was also employed to evaluate their second-order nonlinear optical properties.