The rate of ring closure (k C ) of o-(ω-alkenyl)aryl radicals by means of an intramolecular attack of the intermediate phenyl-type radical at the tethered double bond was found to be 4.2 × 10 8 s −1 (for 1 • ) and 7.6×10 7 s −1 (for 8 • ), both being 6-exo-trig processes, and 9.6 × 10 9 s −1 for the 5-exo-trig process of 3 • . The k C rate constant of these radicals was calibrated with respect to a known rate of H-atom abstraction (k H ). The photostimulated S RN 1 reactions of radical clock precursor 1 with anions PhS − and (EtO) 2 PO − in Me 2 SO at 25°C provided the rates of addition of these nucleophiles (k Y ) to intermediate 1 • (3.2 × 10 8 and 2.5 × 10 9 M −1 s −1 , respect-
A class of iron(III) complexes containing diversely substituted cross-bridged cyclams (1-R,R′: 1-Me,Me, 1-Me,Et, 1-Et,Et, 1-Me,Bn, 1-Bn,Bn) has been prepared and characterized.(1-R,R′) complexes catalyze the oxidation of alcohols to ketones in green conditions, by using tert-butylhydroperoxide as the oxidant in aqueous solutions. They also exhibit catalytic [a]
Octahedral Pt(IV)
complexes (
2Pt–R
) containing a glycoconjugate
carbene ligand were prepared and fully characterized. These complexes
are structural analogues to the trigonal bipyramidal Pt(II) species
(
1Pt–R
) recently described. Thus, an unprecedented
direct comparison between the biological properties of Pt compounds
with different oxidation states and almost indistinguishable structural
features was performed. The stability profile of the novel Pt(IV)
compounds in reference solvents was determined and compared to that
of the analogous Pt(II) complexes. The uptake and antiproliferative
activities of
2Pt–R
and
1Pt–R
were evaluated on the same panel of cell lines. DNA and protein
binding properties were assessed using human serum albumin, the model
protein hen egg white lysozyme, and double stranded DNA model systems
by a variety of experimental techniques, including UV–vis absorption
spectroscopy, fluorescence, circular dichroism, and electrospray ionization
mass spectrometry. Although the compounds present similar structures,
their in-solution stability, cellular uptake, and DNA binding properties
are diverse. These differences may represent the basis of their different
cytotoxicity and biological activity.
The growing concern about global warming and the consumption of fossil fuels has driven in recent decades the use of biomass as a renewable feedstock. In this context, vegetable oils, the corresponding fatty acids (FAs) and esters (FAEs) have primary importance: their esterification and transesterification lead to innovative products, that find application in several sectors, from biofuels to solvents, from surfactants to cosmetic ingredients and plasticizers. Lewis acid catalysis represents the most accredited methodology for developing processes of esterification and transesterification in line with sustainability requirements. The results available so far reveal the prevalent catalytic role of Zn(II) salts and coordination compounds, due to their beneficial eco-toxicological profile, combined with an appropriate acidity, finely tunable through selective functionalization. This review provides a picture of the state of the art in this important sector of biomass valorization. Roberto Esposito received his PhD in Chemical Sciences in 2018 at the University of Naples Federico II under the supervision of prof. F. Ruffo. He is researcher at the Department of Chemical Science of the University of Naples Federico II and his main research topics are W (VI), Zn(II) and Fe(III) based catalysts for conversion of biomasses and chemistry of tetra-coordinated and penta-coordinated complexes of Pt(II). Massimo Melchiorre graduated in Chemical Sciences in 2018. He is Board Member of ISusChem s.r.l., innovative start-up and university spin-off at the Dipartimento di Scienze Chimiche of the Università di Napoli Federico II. Company activity consists in biomass conversion and bio-based products development.
Five‐coordinate platinum(II) complexes represent a minority compared to the well‐known class of square‐planar species. However, since the first appearances in the literature, their general properties have attracted much interest. In particular, their potential to act as anticancer agents has been considered, and several studies have demonstrated their effectiveness as pro‐drugs. The review traces the progress of these investigations over time and the subsequent refinements in the structures. It also reports their synthesis, general properties, cytotoxic activity and ability to interact with biological macromolecules.
This article describes the synthesis, characterization, and biological activity of novel square-planar cationic platinum(II) complexes containing glucoconjugated triazole ligands and a comparison with the results obtained from the corresponding five-coordinate complexes bearing the same triazole ligands. Stability in solution, reactivity with DNA and small molecules of the new compounds were evaluated by NMR, fluorescence, and UV–vis absorption spectroscopy, together with their cytotoxic action against pairs of immortalized and tumorigenic cell lines. The results show that the square-planar species exhibit greater stability than the corresponding five-coordinate ones. Furthermore, although the square-planar complexes are less cytotoxic than the latter ones, they exhibit a certain selectivity. These results simultaneously demonstrate that overall stability is a fundamental prerequisite for preserving the performance of the agents and that coordinative saturation constitutes a point in favor of their biological action.
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