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The Fe3O4/Au/Eu(TTA)3 nanocomposite was functionalized with amino groups, which folic acid was attached to the amino groups to permit targeting of certain cancer cell lines that express high levels of folate receptor. In this paper, a Fe3O4/Au/Eu(TTA)3-folate nanocomplex was successfully synthesized. The as-synthesized material has small size from 75 to 100 nm in diameter and good dispersity in solution. In addition, this nanocomplex exhibits strong emission at λmax = 614 nm, superparamagnetic properties and high biocompatibility.

The second-order nonlinear optical (NLO) properties of [Ln(hfac)(3)(diglyme)] (hfac = hexafluoroacetylacetonate; diglyme = bis(2-methoxyethyl)ether; Ln = La, Ce, Pr, Sm, Eu, Gd, Er, Lu) complexes have been investigated by a combination of electric-field second harmonic generation (EFISH) and harmonic light scattering (HLS) techniques, providing evidence for the relevant role of f electrons in tuning the second-order NLO response dominated by the octupolar contribution. These lanthanide NLO chromophores allow a clean valuation of the influence of f electrons on the quadratic hyperpolarizability and on its dipolar and octupolar contributions. Molecular quadratic hyperpolarizability values measured by the EFISH method, beta(EFISH), initially increase rapidly with the number of f electrons, the value for the Gd complex being 11 times that of the La complex, whereas this increase is much lower for the last seven f electrons, the beta(EFISH) value of the Lu complex being only 1.2 times that of the Gd complex. The increase of , which is dominated by an octupolar contribution, is much lower along the Ln series. Remarkably, the good values of these simple systems, well known for their luminescence properties, are reached at no cost of transparency.

We propose new strategies to increase and control molecular second-order nonlinearities, byusing photoswitching processes or plasmonic resonance. First, we report on reversible switching of nonlinear optical (NLO) properties, based on the use of dipolar or octupolar metal complexes containing photochromic ligands like dithienylethene (DTE) derivatives. DTE undergo a reversible interconversion between a non-conjugated open form and a π-conjugated closed form. A strong relative change of the quadratic molecular nonlinearity upon visible light exposure (more than one order of magnitude) is evidenced by second harmonic generation experiments. This process is fully reversible. On another hand, we explore the quadratic NLO properties of highly NLO dyes (stilbazolium derivatives) grafted onto the surface of gold nanoparticles (NP). In spite of the fact that the plasmon resonance wavelength of gold NPs lies far from that of the second harmonic signal at 820 nm, a significant increase of the nonlinear response of this dye (when linked to a gold nanoparticle) due to surface Plasmon resonance with gold NPs is shown by Harmonic Light Scattering at 1.64 μm. The nature of the linker has a significant influence of hyperpolarizability values, and a similar, but weaker enhancement effect, is also reported in the case of dye/NP mixtures.