Advanced Synthesis and Characterization of Vanadia/Titania Catalysts through a Molecular Approach

Vanadia/titania catalysts were synthesized by the equilibrium deposition filtration (EDF) method, which is a synthesis route that follows a molecular-level approach. The type of interfacial deposition as well as the interfacial speciation of the deposited oxo-V(V) species were determined by means of a model that takes into account experimental “proton-ion” curves and “adsorption edges”. It is shown that at pH ≥ 9.5, the deposition proceeds exclusively through the formation of mono-substituted inner sphere monomeric species in an “umbrella”-like Ti–OV(OH)2O configuration, whilst with lowering of the pH, a second species, namely the disubstituted inner sphere quadrameric species in a (Ti-O)2V4O10 configuration possessing two mono-oxo V=O and two di-oxo V(=O)2 terminations gradually prevails, which is in co-existence with the monomeric species. Raman spectroscopy is used for verifying the solution speciation, which is different compared to the interfacial speciation of the deposited oxo-V(V) species. Furthermore, in situ Raman spectroscopy was used to verify the model-predicted interfacial speciation of the deposited oxo-V(V) species and to monitor the temperature-dependent evolution up to 430 °C. Hence, a controlled formation of a specific vanadia species on a titania surface is enabled, which, depending on the synthesis conditions, can result in specific catalyst characteristics and thus possibly different catalytic behavior for a specific reaction.

Synthesis and crystal structure of one new Pb(II) complex constructed by 1,10-phenanthroline and two carboxylate ligands

The complex [Pb(phen)(4-NB)(CH3COO)] of lead(II) was prepared and characterized by means of elemental analysis, FT-IR, and single crystal X-ray analysis, where phen = 1,10-phenanthroline, 4-NB = 4-nitrobenzoate. The single crystal X-ray analysis indicates that the complex is a monomeric species, including two carboxylate ligands, and adopts a hemidirected structure. It is further extended by intermolecular C−H⋯O hydrogen bonds, π–π interactions and secondary Pb⋯O interactions to form two-dimensional supramolecular architecture.

Dually directional glycosylated phthalocyanines as extracellular red-emitting fluorescent probes

Control of the spatial orientation of glycosylated peripheral substituents in phthalocyanines provides monomeric species that are highly fluorescent in water. Due to their hydrophilic nature, they are suitable as extracellular fluorescent probes.

Insights into the G-rich VEGF-binding aptamer V7t1: when two G-quadruplexes are better than one!

The G-quadruplex-forming VEGF-binding aptamer V7t1 was previously found to be highly polymorphic in a K+-containing solution and, to restrict its conformational preferences to a unique, well-defined form, modified nucleotides (LNA and/or UNA) were inserted in its sequence. We here report an in-depth biophysical characterization of V7t1 in a Na+-rich medium, mimicking the extracellular environment in which VEGF targeting should occur, carried out combining several techniques to analyse the conformational behaviour of the aptamer and its binding to the protein. Our results demonstrate that, in the presence of high Na+ concentrations, V7t1 behaves in a very different way if subjected or not to annealing procedures, as evidenced by native gel electrophoresis, size exclusion chromatography and dynamic light scattering analysis. Indeed, not-annealed V7t1 forms both monomeric and dimeric G-quadruplexes, while the annealed oligonucleotide is a monomeric species. Remarkably, only the dimeric aptamer efficiently binds VEGF, showing higher affinity for the protein compared to the monomeric species. These findings provide new precious information for the development of improved V7t1 analogues, allowing more efficient binding to the cancer-related protein and the design of effective biosensors or theranostic devices based on VEGF targeting.

Synthesis and Structural Characterization of Two New Main Group Element Carboranylamidinates

Two new main group element carboranylamidinates were synthesized using a bottom-up approach starting from o-carborane, ortho-C2B10H12 (1, = 1,2-dicarba-closo-dodecaborane). The first divalent germanium carboranylamidinate, GeCl[HLCy] (3, [HLCy]− = [o-C2B10H10C(NCy)(NHCy)]−, Cy = cyclohexyl), was synthesized by treatment of GeCl2(dioxane) with 1 equiv. of in situ-prepared Li[HLCy] (2a) in THF and isolated in 47% yield. In a similar manner, the first antimony(III) carboranylamidinate, SbCl2[HLiPr] (4, [HLiPr]− = [o-C2B10H10C(NiPr)(NHiPr)]−), was obtained from a reaction of SbCl3 with 1 equiv. of Li[HLiPr] in THF (56% yield). The title compounds were fully characterized by analytical and spectroscopic methods as well as single-crystal X-ray diffraction. Both compounds 3 and 4 are monomeric species in the solid state, and the molecular geometries are governed by a stereo-active lone pair at the metal centers.

Studie über den Einfluss des Fluorierungsgrades an einem tetradentaten C^N*N^C-Luminophor auf die photophysikalischen Eigenschaften seiner Platin(II)-Komplexe und deren Aggregation

Herein, we present three new tetradentate C^N*N^C luminophores and their platinum(II) complexes. We describe the influence of the degree of fluorination at the phenylpyridine luminophore on the photophysical properties of the monomeric species. A blue-shift can be observed with increasing number of fluorine atoms (0–6), which is related to a growing HOMO-LUMO gap that reaches a maximum for four halogen moieties. Increasing degree of fluorination enables intermolecular Pt–Pt interactions and promotes emission from 3MMLCT states in amorphous solids and matrices, with the drawback of lowered solubility. A clear trend towards layered packing patterns in crystals has been observed within the series. This knowledge is important for the design and realization of triplet emitters with aggregation-controlled luminescence towards potential applications in optoelectronic devices.

NEW TRANSITION METAL OXALATO COMPLEXES WITH DABCOH22+ AS ADVERSE CATION: SYNTHESIS AND INFRARED STUDY

<p>On allowing DABCOH₂(HC₂O₄)₂ to react with transition metal dihalides in ethanol, a new series of complexes of general formula M(oxalate)₂ DABCOH₂²⁺. nDABCOH₂²⁺.2X^- (n=1/2;1) have been obtained. When (n=1) a dimeric structure is suggested, the two monomeric species being hold together by biprotonated DABCO through N-H…O hydrogen bonds. In the case of the complex M(oxalate)₂DABCOH₂²⁺.1/2 DABCOH₂²⁺.2X^--M = Ni, Cu- the structure is an infinite chain. The environment around the metallic centers is octahedral or square pyramidal. The oxalate behaves as a monochelating and hydrogen bonds involved ligand or is only concerned by hydrogen bonds.</p>

NEW TRANSITION METAL OXALATO COMPLEXES WITH DABCOH22+ AS ADVERSE CATION: SYNTHESIS AND INFRARED STUDY

On allowing DABCOH2(HC2O4)2 to react with transition metal dihalides in ethanol, a new series of complexes of general formula M(oxalate)2 DABCOH22+. nDABCOH22+.2X- (n=1/2;1) have been obtained. When (n=1) a dimeric structure is suggested, the two monomeric species being hold together by biprotonated DABCO through N-H…O hydrogen bonds. In the case of the complex M(oxalate)2DABCOH22+ .1/2 DABCOH22+.2X- -M = Ni, Cu- the structure is an infinite chain. The environment around the metallic centers is octahedral or square pyramidal. The oxalate behaves as a monochelating and hydrogen bonds involved ligand or is only concerned by hydrogen bonds.