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Biomass represents an abundant and renewable source of raw materials that can be effectively converted into intermediates and base chemicals. Among these, levulinic acid has garnered significant attention due to its direct derivation from lignocellulosic biomass and the presence of two functional groups, a carboxylic acid, and a ketone, enabling diverse transformations into valuable products. Levulinic acid esters have already found applications in various industrial sectors such as cosmetics, plasticizers, and solvents. In this study, a broad array of alkyl levulinates has been successfully synthesized through homogeneous transesterification catalyzed by Lewis acids. A systematic screening of a library of μ‐oxo‐dinuclear Fe(III) salen complexes has been conducted, aiming to elucidate the impact of steric and electronic properties of their substituents. A complementary theoretical‐computational study based on quantum mechanics calculations and machine learning regression techniques has been employed to unravel the relationship between the structure of the catalysts and their corresponding properties, shedding light on the key factors influencing their catalytic performance. [ABSTRACT FROM AUTHOR]

This article presents an efficient iron(III) molecular catalyst for the production of biodiesel from waste vegetable oils. The approach involved an initial screening of eight salophen complexes with various substituents on the arene rings, leading to the selection of the simplest unsubstituted species as the most active catalyst. Under optimized conditions, this catalyst demonstrated the capability to achieve complete conversion of the oil at a low catalyst loading (0.10% mol/mol) and convenient conditions (160 °C, 20/1 MeOH/oil ratio). [ABSTRACT FROM AUTHOR]

The present review articles the most recent efforts, made in the Department of Chemical Sciences of the University of Naples Federico II, in the catalytic treatment of biomasses derived from vegetable oils. The review is focused on several technologies aimed at the production of either biofuels or valuable chemicals: (i) biodiesel production; (ii) esterification to obtain high‐added value products; (iii) epoxidation of vegetable oils; (iv) glycerol ketalization; (v) oxidative cleavage of unsaturated fatty acids. The results are critically summarized to highlight the scientific activities and the main results in the field of biorefinery concept. [ABSTRACT FROM AUTHOR]

This study describes new platinum(II) cationic five-coordinate complexes (1-R,R') of the formula [PtR(NHC)(dmphen)(ethene)]CF3SO3 (dmphen = 2,9-dimethyl-1,10-phenanthroline), containing in their axial positions an alkyl group R (methyl or octyl) and an imidazole-based NHC-carbene ligand with a substituent R' of variable length (methyl or octyl) on one nitrogen atom. The Pt–carbene bond is stable both in DMSO and in aqueous solvents. In DMSO, a gradual substitution of dmphen and ethene is observed, with the formation of a square planar solvated species. Octanol/water partitioning studies have revealed the order of hydrophobicity of the complexes (1-Oct,Me > 1-Oct,Oct > 1-Me,Oct > 1-Me,Me). Their biological activity was investigated against two pairs of cancer and non-cancer cell lines. The tested drugs were internalized in cancer cells and able to activate the apoptotic pathway. The reactivity of 1-Me,Me with DNA and protein model systems was also studied using UV–vis absorption spectroscopy, fluorescence, and X-ray crystallography. The compound binds DNA and interacts in various ways with the model protein lysozyme. Remarkably, structural data revealed that the complex can bind lysozyme via non-covalent interactions, retaining its five-coordinate geometry. [ABSTRACT FROM AUTHOR]

The catalytic properties of a simple iron-containing MOF based on fumaric acid, MIL-88A, were investigated in the ketalization of ethyl levulinate with glycerol. The corresponding product is a component of current interest as a renewable building block for many uses. Under the following conditions (solventless, 120 °C, stoichiometric ratio, 1% cat.), the reaction proceeds with good yields (85%), and the catalyst can be recovered and recycled without loss of activity, despite some changes in the crystalline lattice and morphology. Moreover, the residual iron content in the product is in the order of units of ppm (≤2), which demonstrates the robustness of the MOF under the reaction conditions. [ABSTRACT FROM AUTHOR]

New neutral carbene complexes of gold(I) [Au(Im-Me)X] (X = Cl, Au1; X = Br, Au2; X = I, Au3) have been synthesized and fully characterized by different techniques, including NMR and UV-vis absorption spectroscopy and single crystal X-ray diffraction. The carbene ligand Im-Me is decorated with a glucoside fragment via a triazole linker, obtainable through a click chemistry reaction. The compounds retain the Au–NHC fragment in aqueous solvents, and an equilibrium between the neutral halo- and the cationic di-carbene form [Au(Im-Me)2]+ is observed, whose extent follows the trend Au1 < Au2 < Au3. Cytotoxicity studies on two cancer and two non-tumorigenic cell lines reflect the solution behavior, as a certain difference among the complexes was disclosed, with the iodo complex Au3 being more active and selective. The compounds interact with both DNA and protein model systems. The X-ray structure of the adduct formed upon the reaction of Au1 with bovine pancreatic ribonuclease (RNase A) reveals Au binding at the side chain of His105 of both protein molecules A and B of the asymmetric unit. The binding of gold atoms at both the nitrogen atoms of the imidazole ring of His15 and at the N-terminal tail has been found in the adduct formed with hen egg white lysozyme. [ABSTRACT FROM AUTHOR]

The oxidative addition of α‐glucosyl and α‐galactosyl halides to the platinum(0) complex [Pt(2,9‐dimethyl‐1,10‐phenanthroline)(ethene)] has been investigated. In all cases the main reaction product is the five‐coordinate Pt(II) complex containing in axial position an α‐glycosyl fragment in the unusual 1C4 conformation. In the case of glucose, a minor product could be identified as the β isomer, which retains the typical 4C1 chair. The single crystal structures of two diastereomers are compared. The outcome of the reaction does not depend on the nature of the halide and is only slightly affected by the solvent. The addition mechanism is discussed, also in the light of literature data. Experimental data, along with DFT calculations, point towards a radical chain mechanism. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

New five-coordinate Pt(ii) complexes containing a glycosylated carbene fragment were synthesized. A member of this class shows very high in vitro cytotoxicity and an exceptional selectivity toward malignant cells. The complex lacking the sugary portion fails in the recognition of cancer cells. The results support the use of glycosylation in the design of carbene Pt-based anticancer agents. [ABSTRACT FROM AUTHOR]

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 activity in water oxidation (WO) to molecular oxygen driven by NaIO4, and the results were found to be dependent on the steric hindrance of the R‐substituents. Best compromise in terms of accessibility and protection of the metal center was obtained with 1‐Me,Et (TOF = 1.4 min–1 and TON = 111). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Stable five-coordinate Pt(II) complexes have been highlighted as a promising and original platform for the development of new cytotoxic drugs. Their interaction with proteins has been scarcely studied. Here, the reactivity of the five-coordinate Pt(II) compound [Pt(I)(Me) (dmphen)(olefin)] (Me = methyl, dmphen = 2,9-dimethyl-1,10-phenanthroline, olefin = dimethylfumarate) with the model proteins hen egg white lysozyme (HEWL) and bovine pancreatic ribonuclease (RNase A) has been investigated by X-ray crystallography and electrospray ionization mass spectrometry. The X-ray structures of the adducts of RNase A and HEWL with [Pt(I)(Me)(dmphen)(olefin)] are not of very high quality, but overall data indicate that, upon reaction with RNase A, the compound coordinates the side chain of His105 upon releasing the iodide ligand, but retains the pentacoordination. On the contrary, upon reaction with HEWL, the trigonal bi-pyramidal Pt geometry is lost, the iodide and the olefin ligands are released, and the metal center coordinates the side chain of His15 probably adopting a nearly square-planar geometry. This work underlines the importance of the combined use of crystallographic and mass spectrometry techniques to characterize, in detail, the protein–metallodrug recognition process. Our findings also suggest that five-coordinate Pt(II) complexes can act either retaining their uncommon structure or functioning as prodrugs, i.e., releasing square-planar platinum complexes as bioactive species. [ABSTRACT FROM AUTHOR]