NIR-to-NIR Two-Photon Scanning Laser Microscopy Imaging of Single Nanoparticles Doped by Yb(III) Complexes.

The photophysical and nonlinear optical properties of water-soluble chromophore-functionalised tris-dipicolinate complexes [LnL3](3-) (Ln=Yb and Nd) are thoroughly studied, revealing that only the Yb(III) luminescence can be sensitized by a two-photon excitation process. The stability of the complex in water is strongly enhanced by embedding in dispersible organosilicate nanoparticles (NPs). Finally, the spectroscopic properties of [NBu4]3 [YbL3] are studied in solution and in the solid state. The high brightness of the NPs allows imaging them as single objects using a modified two-photon microscopy setup in a NIR-to-NIR configuration.

Influence of the metal ion on the two-photon absorption properties of lanthanide complexes including near-IR emitters.

The synthesis of tris(2-thenoyltrifluoroacetonate)lanthanide(III) complexes featuring a diethylaminostyryl-2,2'-bipyridine coligand was achieved for lanthanum; the near-infrared (NIR) emitters neodymium, erbium, and ytterbium; and the transition-metal yttrium. The photophysical properties were thoroughly studied, and it was demonstrated that the conjugated bipyridine ligand acts as a good antenna for the sensitization of the NIR emitters. The two-photon absorption (TPA) properties of all five complexes were investigated by using both two-photon excited fluorescence and the Z-scan method. We demonstrate that the nature of the rare earth ion has almost no influence on the TPA properties centered on the conjugated bipyridyl ligand. Finally, we show that Yb(III) is sensitized by a two-photon antenna effect, and that Nd(III) is mostly sensitized by a one-photon process involving direct excitation of forbidden f-f transitions.

Very bright europium complexes that stain cellular mitochondria.

The synthesis, structure and photophysical properties of a series of highly emissive europium complexes is reported. Certain complexes enter mammalian cells by macropinocytosis and stain the mitochondria selectively, allowing observation of the Eu emission in cellulo by time-gated spectral imaging.

In solution sensitization of Er(III) luminescence by the 4-tetrathiafulvalene-2,6-pyridinedicarboxylic acid dimethyl antenna ligand.

In the [Er(hfac)(3)(L)](2) complex (1) (L = 4-tetrathiafulvalene-2,6-pyridinecarboxylic acid dimethyl ester), the Er(III) ion is bonded to the tridentate coordination site. Electrochemical and photophysical measurements in solution reveal that the tetrathiafulvalene moiety is a versatile antenna for erbium luminescence sensitization at 6540 cm(-1) upon excitation in the low-energy charge transfer transition (donor to acceptor charge transfer) at 16600 cm(-1) assigned via time-dependent density functional theory calculations.

Non-aqueous solvents for DNP surface enhanced NMR spectroscopy.

A series of non-aqueous solvents combined with the exogenous biradical bTbK are developed for DNP NMR that yield enhancements comparable to the best available water based systems. 1,1,2,2-tetrachloroethane appears to be one of the most promising organic solvents for DNP solid-state NMR. Here this results in a reduction in experimental times by a factor of 1000. These new solvents are demonstrated with the first DNP surface enhanced NMR characterization of an organometallic complex supported on a hydrophobic surface.

Modulating the photophysical properties of azamacrocyclic europium complexes with charge-transfer antenna chromophores.

Two europium complexes with bis(bipyridine) azamacrocyclic ligands featuring pendant arms with or without π-conjugated donor groups are synthesized and fully characterized by theoretical calculations and NMR spectroscopy. Their photophysical properties, including two-photon absorption, are investigated in water and in various organic solvents. The nonfunctionalized ligand gives highly water-stable europium complexes featuring bright luminescence properties but poor two-photon absorption cross sections. On the other hand, the europium complex with an extended conjugated antenna ligand presents a two-photon absorption cross section of 45 GM at 720 nm but is poorly luminescent in water. A detailed solvent-dependent photophysical study indicates that this luminescence quenching is not due to the direct coordination of O-H vibrators to the metal center but to the increase of nonradiative processes in a protic solvent induced by an internal isomerization equilibrium.

d-f heterobimetallic association between ytterbium and ruthenium carbon-rich complexes: redox commutation of near-IR luminescence.

We describe how the association between an ytterbium ion and a ruthenium carbon-rich complex enables the first switching of the near-IR Yb(III) luminescence by taking advantage of the redox commutation of the carbon-rich antenna.