Sorption of ofloxacin and chrysoidine by grape stalk. A representative case of biomass removal of emerging pollutants from wastewater

Emerging pollutants, as antibiotics or dyes, in aquatic ecosystems are a crucial concern and numerous techniques have been developed for their removal. Efficiency, cost effectiveness, and biodegradability reveal biomass sorption as one of the most appealing methods. This study aims to evaluate the effectiveness of grape stalk as a sorbent for ofloxacin (a fluoroquinolone antibiotic) and chrysoidine (an azo-dye). The kinetic and the thermodynamic aspects of the sorption were studied. A pseudo first-order kinetic behavior is shown by both substances, though the kinetic constants of ofloxacin are almost double than those of chrysoidine. The sorption isotherms, which strictly follow the Langmuir model, show remarkable differences as a function of pH and of biomass size. The trend of Langmuir parameters, Qmax and K, as a function of pH and size, is discussed, and different binding mechanisms are proposed. Kinetic and thermodynamic parameters prefigure grape stalk as a potential biomass for scavenging toxic substances from wastewater

Classical vs. Non-classical cyclometalated pt(ii) complexes

Rollover cyclometalated complexes constitute a family of derivatives which differ from classical cyclometalated species in certain aspects. Various potential application fields have been developed for both classes of compounds, which have both similarities and differences. In order to uncover the relationships and distinctions between these two families of compounds, four Pt(II) cyclometalated complexes derived from 2-phenylpyridine (ppy) and 2,2′-bipyridine (bpy), assumed as prototypical ligands, were compared. For this study, an electron rich isostructural and isoelectronic pair of compounds, [Pt(N^C)Me(PPh3)], and an electron-poorer compound, [Pt(N^C)Cl(PPh3)] were chosen (N^C = ppy or bpy). DFT calculations, cyclic voltammetry, and UV-Vis spectra also helped to shed light into these species. Due to the presence of the more electronegative nitrogen in place of a C-H group, the rollover bpy-H ligand becomes a slightly weaker donor than the classical ppy-H ligand, and hence, generates (slightly) more stable cyclometalated complexes, lower energy frontier molecular orbitals, and electron-poorer platinum centers. On the whole, it was revealed that classical and rollover complexes have overall structural similarity, which contrasts to their somewhat different chemical behavior

Elemental Fingerprinting Combined with Machine Learning Techniques as a Powerful Tool for Geographical Discrimination of Honeys from Nearby Regions

Discrimination of honey based on geographical origin is a common fraudulent practice and is one of the most investigated topics in honey authentication. This research aims to discriminate honeys according to their geographical origin by combining elemental fingerprinting with machinelearning techniques. In particular, the main objective of this study is to distinguish the origin of unifloral and multifloral honeys produced in neighboring regions, such as Sardinia (Italy) and Spain. The elemental compositions of 247 honeys were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The origins of honey were differentiated using Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), and Random Forest (RF). Compared to LDA, RF demonstrated greater stability and better classification performance. The best classification was based on geographical origin, achieving 90% accuracy using Na, Mg, Mn, Sr, Zn, Ce, Nd, Eu, and Tb as predictor

Elemental fingerprinting combined with machine learning techniques as a powerful tool for geographical discrimination of honeys from nearby regions

Discrimination of honey based on geographical origin is a common fraudulent practice and is one of the most investigated topics in honey authentication. This research aims to discriminate honeys according to their geographical origin by combining elemental fingerprinting with machine-learning techniques. In particular, the main objective of this study is to distinguish the origin of unifloral and multifloral honeys produced in neighboring regions, such as Sardinia (Italy) and Spain. The elemental compositions of 247 honeys were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The origins of honey were differentiated using Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), and Random Forest (RF). Compared to LDA, RF demonstrated greater stability and better classification performance. The best classification was based on geographical origin, achieving 90% accuracy using Na, Mg, Mn, Sr, Zn, Ce, Nd, Eu, and Tb as predictors

Rollover Cyclometalation as a Valuable Tool for Regioselective C–H Bond Activation and Functionalization

Rollover cyclometalation constitutes a particular case of cyclometallation reaction. This reaction occurs when a chelated heterocyclic ligand loses its bidentate coordination mode and undergoes an internal rotation, after which a remote C–H bond is regioselectively activated, affording an uncommon cyclometalated complex, called “rollover cyclometalated complex”. The key of the process is the internal rotation of the ligand, which occurs before the C–H bond activation and releases from coordination a donor atom. The new “rollover” ligand has peculiar properties, being a ligand with multiple personalities, no more a spectator in the reactivity of the complex. The main reason of this peculiarity is the presence of an uncoordinated donor atom (the one initially involved in the chelation), able to promote a series of reactions not available for classic cyclometalated complexes. The rollover reaction is highly regioselective, because the activated C–H bond is usually in a symmetric position with respect to the donor atom which detaches from the metal stating the rollover process. Due to this novel behavior, a series of potential applications have appeared in the literature, in fields such as catalysis, organic synthesis, and advanced materials

Rollover Cyclometalation as a Valuable Tool for Regioselective C–H Bond Activation and Functionalization

Rollover cyclometalation constitutes a particular case of cyclometallation reaction. This reaction occurs when a chelated heterocyclic ligand loses its bidentate coordination mode and undergoes an internal rotation, after which a remote C–H bond is regioselectively activated, affording an uncommon cyclometalated complex, called “rollover cyclometalated complex”. The key of the process is the internal rotation of the ligand, which occurs before the C–H bond activation and releases from coordination a donor atom. The new “rollover” ligand has peculiar properties, being a ligand with multiple personalities, no more a spectator in the reactivity of the complex. The main reason of this peculiarity is the presence of an uncoordinated donor atom (the one initially involved in the chelation), able to promote a series of reactions not available for classic cyclometalated complexes. The rollover reaction is highly regioselective, because the activated C–H bond is usually in a symmetric position with respect to the donor atom which detaches from the metal stating the rollover process. Due to this novel behavior, a series of potential applications have appeared in the literature, in fields such as catalysis, organic synthesis, and advanced materials

Electrochemical properties of copper complexes with unsubstituted and substituted 1,10-o-phenanthrolines in N,N-dimethylformamide solvent

The electrochemical reduction of a series of copper(II) complexes with 1,10-o-phenanthrolines, namely the 1:1 and 1:2 metal:ligand complexes with 2,9-dimethylphenanthroline, 4,7-dimethylphenanthroline and unsubstituted phenanthroline, respectively, has been studied in N,N-dimethylformamide using platinum electrodes. As to the 1:2 complexes, the effect of the presence of substituents with different electronic and steric effects on the phenanthroline ligands has been studied with the aim of rationalizing the different values of the standard potentials which have been measured. Furthermore, the possibility of electrogenerating neutral species, with a formally zerovalent copper centre, exhibiting different stability depending on the nature of the ligands, has been ascertained. In out solvent medium, 1:1 complexes have been found to be in equilibrium with the corresponding 1:2 complexes. A scheme for the reduction of solutions of these compounds, including the different equilibria associated to the electrode charge transfers, has been outlined

Ru(terpy)-Based Conducting Polymer in Electrochemical Biosensing of Epinephrine

A heteroleptic [Ru(terpy)2]2+ (terpy = 2,2′:6′,2″-terpyridine) complex was electrochemically polymerized to give the corresponding metal-containing conducting polymer on gold and glassy carbon electrodes. The polymerization of the Ru(II) complex was allowed by a terthiophene functionalization on one of the two terpy coordinating fragments, whereas the presence of -COOH substituents on the second terpy ligand enabled the film to immobilize a tyrosinase enzyme by cross-linking with glutaraldehyde. Then, the Ru(terpy) conducting polymer worked as a transducer as well as an immobilizing agent in the design of amperometric biosensors for the determination of epinephrine. The electrochemical behavior of enzymatic sensors containing Ru(terpy)-based conducting polymers was investigated by differential pulse voltammetry and chronoamperometry. Analytical performances and kinetic parameters were calculated, suggesting a potential application of the reported biosensors in the determination of epinephrine in pharmaceutical products

Electrochemistry of the pyrazolate-bridged dirhodium(I) complex Rh2(CO)2(PPh3)2(μ-3,5-Me2pz)2

The dirhodium(I) complex Rh2(CO)2(PPh3)2(mu-3,5-Me2pz)2 undergoes two consecutive oxidation processes at a platinum electrode in dichloromethane. The first oxidation gives the corresponding cationic species, [Rh2(CO)2(PPh3)2(mu-3,5-Me2pz)2]+, as inferred from the electrochemical (voltammetric and coulometric) and spectroelectrochemical data and from spectroscopic (IR, ESR and visible) examination of the oxidized product. The more anodic process involves poisoning adsorptions on the electrode surface, which rules out any effective study. Suggestions concerning the electronic charge distribution inside the monocationic compound are advanced on the basis of the voltammetric and ESR data