Towards High-Performance Photo-Fenton Degradation of Organic Pollutants with Magnetite-Silver Composites: Synthesis, Catalytic Reactions and In Situ Insights.

In this study, FeO/Ag magnetite-silver (MSx) nanocomposites were investigated as catalysts for advanced oxidation processes by coupling the plasmonic effect of silver nanoparticles and the ferromagnetism of iron oxide species. A surfactant-free co-precipitation synthesis method yielded pure FeO magnetite and four types of MSx nanocomposites. Their characterisation included structural, compositional, morphological and optical analyses, revealing FeO magnetite and Ag silver phases with particle sizes ranging from 15 to 40 nm, increasing with the silver content.

Viologen-cucurbituril host/guest chemistry - redox control of dimerization inclusion.

Two calix[4]arene systems, C23 and C24 - where 2 corresponds to the number of viologen units and 3-4 corresponds to the number of carbon atoms connecting the viologen units to the macrocyclic core - have been synthesized and led to the formation of [3]pseudorotaxanes when combined with either CB[7] or CB[8]. The [3]pseudorotaxanes spontaneously dissociate upon reduction of the bipyridinium units as the result of intramolecular dimerization of the two face-to-face viologen radical cations. CB[7] and CB[8]-based [2]pseudorotaxanes containing monomeric viologen guest model compounds, MC3 and MC, do not undergo decomplexation and dimerization following electrochemical reduction of their bipyridinium units.

Viologen-templated arrays of cucurbit[7]uril-modified iron-oxide nanoparticles.

Magnetic and fluorescent assemblies of iron-oxide nanoparticles (NPs) were constructed by threading a viologen-based ditopic ligand, DPV(2+), into the cavity of cucurbituril (CB[7]) macrocycles adsorbed on the surface of the NPs. Evidence for the formation of 1:2 inclusion complexes that involve DPV(2+) and two CB[7] macrocycles was first obtained in solution by (1)H NMR and emission spectroscopy. DPV(2+) was found to induce self-assembly of nanoparticle arrays (DPV(2+)⊂CB[7]NPs) by bridging CB[7] molecules on different NPs.

Supramolecular luminescent lanthanide dimers for fluoride sequestering and sensing.

Lanthanide complexes (Ln=Eu, Tb, and Yb) that are based on a C2 -symmetric cyclen scaffold were prepared and characterized. The addition of fluoride anions to aqueous solutions of the complexes resulted in the formation of dinuclear supramolecular compounds in which the anion is confined into the cavity that is formed by the two complexes. The supramolecular assembly process was monitored by UV/Vis absorption, luminescence, and NMR spectroscopy and high-resolution mass spectrometry.

Radical-cation dimerization overwhelms inclusion in [N]pseudorotaxanes.

Suppression of the dimerization of the viologen radical cation by cucurbit[7]uril (CB7) in water is a well-known phenomenon. Herein, two counter-examples are presented. Two viologen-containing thread molecules were designed, synthesized, and thoroughly characterized by (1)H DOSY NMR spectrometry, UV/Vis absorption spectrophotometry, square-wave voltammetry, and chronocoulometry: BV(4+), which contains two viologen subunits, and HV(12+), which contains six.

Photophysical evaluation of a new functional terbium complex in FRET-based time-resolved homogenous fluoroassays.

A new functional luminescent lanthanide complex (LLC) has been synthesized with terbium as a central lanthanide ion and biotin as a functional moiety. Unlike in typical lanthanide complexes assembled via carboxylic moieties, in the presented complex, four phosphate groups are chelating the central lanthanide ion. This special chemical assembly enhances the complex stability in phosphate buffers conventionally used in biochemistry.

Activated phosphonated trifunctional chelates for highly sensitive lanthanide-based FRET immunoassays applied to total prostate specific antigen detection.

The first example of an activated phosphonated trifunctional chelate (TFC) is presented, which combines a non-macrocyclic coordination site for lanthanide coordination based on two aminobis-methylphosphonate coordinating arms, a central bispyrazolylpyridyl antenna and an N-hydroxysuccinimide ester in para position of the central pyridine as an activated function for the labeling of biomaterial. The synthesis of the TFC is presented together with photo-physical studies of the related Tb and Eu complexes. Excited state lifetime measurements in H2O and D2O confirmed an excellent shielding of the cation from water molecules with a hydration number of zero.

Stable and highly fluorescent europium(III) chelates for time-resolved immunoassays.

Derivatives of 4-[2-(4-isothiocyanatophenyl)ethynyl]-2,6,-bis{[N,N-bis(carboxymethyl)-amino]methyl}pyridine europium(III) (1) bearing one (6) or two (7) additional iminodiacetate coordinating arms have been synthesized. 6 and 7 were significantly more stable than 1 as evidenced by competition experiments with ethylenediaminetetraacetic acid (EDTA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). While the luminescence quantum yield of 1 remained modest, the other two complexes displayed substantial luminescence efficiency.

Nonmacrocyclic luminescent lanthanide complexes stable in biological media.

The synthesis of ligand L(P)H(8), based on a 2,6-bispyrazolyl-pyridine scaffold functionalized by iminobismethylenephosphonate functions, is described and its pK values were determined by a combination of pH-spectrophotometric titrations and potentiometry. The interaction of L(P) with Tb(3+) was investigated in water (0.01 M TRIS/HCl pH = 7.