Heptametallic, Octupolar Nonlinear Optical Chromophores with Six Ferrocenyl Substituents

摘要: New complexes with six ferrocenyl (Fc) groups connected to ZnII or Cd^(II) tris(2,2′-bipyridyl) cores are described. A thorough characterisation of their BPh_(4)− salts includes two single-crystal X-ray structures, highly unusual for such species multiple, extended substituents. Intense, visible d(Fe^(II))→π* metal-to-ligand charge-transfer (MLCT) bands accompany the π→π* intraligand absorptions in near UV region. Each complex shows a single, fully reversible Fe^(III/II) wave when probed electrochemically. Molecular quadratic nonlinear optical (NLO) responses determined by using hyper-Rayleigh scattering and Stark spectroscopy. The latter gives static first hyperpolarisabilities β_0 reaching as high approximately 10^(−27) esu generally increasing π-conjugation extension. Z-scan cubic NLO measurements reveal two-photon absorption cross-sections σ2 up 5400 GM one case. DFT calculations reproduce dependence β_0, TD-DFT predicts three transitions close energy contributing MLCT bands. lowest transition has octupolar character, whereas other degenerate dipolar nature.