Insight into the structure of black coatings of ancient Egyptian mummies by advanced Electron magnetic resonance of vanadyl complexes

Advanced EPR techniques such as ENDOR and pulsed EPR are used to investigate the enigmatic black coatings of ancient Egyptian mummies, consisting in a complex and heterogeneous mixtures of conifer resins, wax, fat and oil with variable amounts of bitumen. Natural bitumen always contains traces of vanadyl porphyrin complexes that we used here as internal probes to explore the nanoscale environment of V4+ ions in these black coatings by hyperfine spectroscopy. Four types of vanadyl porphyrins were identified from the analysis of 14N hyperfine interactions. Three types (referred to as VO-P1, VO-P2 and VO-P3) are present in natural bitumen from the Dead Sea, among which VO-P1 and VO-P2 are also present in black coatings of mummies. The absence of VO-P3 in mummies, which is replaced by another complex VO-P4, may be due to its transformation during preparation of the black matter for embalming. Analysis of 1H hyperfine interaction shows that bitumen and other natural substances are intimately mixed in these black coatings, with bitumen aggregate sizes not larger than a few nanometres.

Effects of Vanadyl Complexes with Acetylacetonate Derivatives on Non-Tumor and Tumor Cell Lines

Vanadium has a good therapeutic potential, as several biological effects, but few side effects, have been demonstrated. Evidence suggests that vanadium compounds could represent a new class of non-platinum, metal antitumor agents. In the present study, we aimed to characterize the antiproliferative activities of fluorescent vanadyl complexes with acetylacetonate derivates bearing asymmetric substitutions on the β-dicarbonyl moiety on different cell lines. The effects of fluorescent vanadyl complexes on proliferation and cell cycle modulation in different cell lines were detected by ATP content using the CellTiter-Glo Luminescent Assay and flow cytometry, respectively. Western blotting was performed to assess the modulation of mitogen-activated protein kinases (MAPKs) and relevant proteins. Confocal microscopy revealed that complexes were mainly localized in the cytoplasm, with a diffuse distribution, as in podocyte or a more aggregate conformation, as in the other cell lines. The effects of complexes on cell cycle were studied by cytofluorimetry and Western blot analysis, suggesting that the inhibition of proliferation could be correlated with a block in the G2/M phase of cell cycle and an increase in cdc2 phosphorylation. Complexes modulated mitogen-activated protein kinases (MAPKs) activation in a cell-dependent manner, but MAPK modulation can only partly explain the antiproliferative activity of these complexes. All together our results demonstrate that antiproliferative effects mediated by these compounds are cell type-dependent and involve the cdc2 and MAPKs pathway.

Exploiting clock transitions for the chemical design of resilient molecular spin qubits

We employ a python computational tool to compare 3 relevant case studies with increasingly complex ground states: vanadyl complexes, Ho(iii) square antiprisms and Ho(iii) cubic structures.

Asymmetric sulfoxidation by C1-symmetric V(IV)O(ONO) (S)-NOBIN Schiff-base vanadyl complexes

C1-symmetric vanadyl Schiff-base complexes were synthesized by reacting vanadium(IV) acetylacetonate with (S)-3-[(1-(2-hydroxynaphthalen-1-yl)naphthalen-2-ylimino]methyl]-phenanthrene-4-ol and (S)-2-{[1-(2-hydroxynaphthalen-1-yl)naphthalen-2-ylimino]methyl}tetraphene-1-ol. The complexes were characterized by MALDI-TOF-MS, UV–vis, and circular dichroism (CD) spectroscopy. The catalysts showed moderate activity for the oxidation of thioanisole to methyphenylsulfoxide with hydrogen peroxide, tert-butyl hydroperoxide, and cumene hydroperoxide as the oxidants.