Selective formation, reactivity, redox and magnetic properties of MnIII and FeIII dinuclear complexes with shortened salen-type schiff base ligands

The reactivity of the shortened salen-type ligands H3salmp, H2salmen and H2sal(p-X)ben with variable para-substituent on the central aromatic ring (X = tBu, Me, H, F, Cl, CF3, NO2) towards the trivalent metal ions manganese(III) and iron(III) is presented. The selective formation of the dinuclear complexes [M2(m-salmp)2], M = Mn (1a), Fe (2a), [M2(m-salmen)2(m-OR)2)], R = Et, Me, H and M = Mn (3a\u2013c) or Fe (4a\u2013c), and (M2(m-sal[p-X]ben)2(m-OMe)2), X = tBu, Me, H, F, Cl, CF3, NO2 and M = Mn (5a\u2013g) or Fe (6a\u2013g), could be identified by reaction of the Schiff bases with metal salts and the base NEt3, and their characterization through elemental analysis, infrared spectroscopy, mass spectrometry and single-crystal X-ray diffraction of 2a.2AcOEt, 2a.2CH3CN and 3c.2DMF was performed. In the case of iron(III) and H3salmp, when using NaOH as a base instead of NEt3, the dinuclear complexes [Fe2(m-salmp)(m-OR)(salim)2], R = Me, H (2b\u2013c) could be isolated and spectroscopically characterized, including the crystal structure of 2b.1.5H2O, which showed that rupture of one salmp3\u2013 to two coordinated salim\u2013 ligands and release of one salH molecule occurred. The same hydrolytic tendency could be identified with sal(p-X)ben ligands in the case of iron(III) also by using NEt3 or upon standing in solution, while manganese(III) did not promote such a C\u2013N bond breakage. Cyclic voltammetry studies were performed for 3b, 4b, 5a and 6a, revealing that the iron(III) complexes can be irreversibly reduced to the mixed-valence FeIIFeIII and FeII2 dinuclear species, while the manganese(III) derivatives can be reversibly oxidized to either the mixed-valence MnIIIMnIV or to the MnIV2 dinuclear species. The super-exchange interaction between the metal centers, mediated by the bridging ligands, resulted in being antiferromagnetic (AFM) for the selected dinuclear compounds 3b, 4b, 5a, 5e, 5f, 6a and 6e. The coupling constants J (\u20132J \u15c1\ub7\u15c2 formalism) had values around \u201313 cm\u20131 for manganese(III) compounds, among the largest AFM coupling constants reported so far for dinuclear MnIII2 derivatives, while values between \u20133 and \u201310 cm\u20131 were obtained for iron(III) compounds

Development of an electrochemical sensor for NADH determination based on caffeic acid redox mediator supported on carbon black

Screen-printed electrode (SPE) modified with carbon black nanoparticles (CB) has been tested as a new platform for the stable deposition of caffeic acid (CFA) on the electrode surface. The electrochemical performance from varying the amount of CFA/CB composite has been tested with respect to NADH determination. The electrocatalytic activity of CFA/CB has also been compared with that of SPEs modified by a single component of the coating, i.e., either CFA or CB. Finally, glycerol dehydrogenase, a typical NADH-dependent enzyme, was deposited on the CFA/CB coating in order to test the applicability of the sensor in glycerol determination

Development of an electrochemical sensor based on carbon black for the detection of cannabidiol in vegetable extracts

A glassy carbon electrode chemically modified with a carbon black coating is proposed here for the rapid and portable determination of cannabidiol (CBD) in a commercial Cannabis seed oil and in fibre-type Cannabis sativa L. leaves. The mechanism of CBD oxidation was studied in relation to simpler phenyl derivatives bearing the same electroactive group, namely resorcinol and 2-methylresorcinol. These molecules also allowed us to determine the best conditions for the electrochemical detection of CBD, as to the pH value and to the best solvent mixture to use. Carbon black was chosen among nanostructured carbon-based materials owing to its outstanding features as an electrode modifier for analyte detection. The performance of the modified electrode was determined by flow injection analyses of standard solutions of CBD, obtaining a linear correlation between the oxidation current and the analyte concentration; the sensor response is characterised by suitable repeatability and reproducibility. The analysis of commercial products by the standard addition method allowed us to ascertain the accuracy of the sensor for the detection of CBD in real samples

Exchange Interactions Drive Supramolecular Chiral Induction in Polyaniline

The focus of this paper is on the intermolecular interaction active between polyaniline (PANI) and 10-camphorsulfonic acid (10CSA). Enantiopure 10CSA, present in the electropolymerization solution, promotes chiral induction in the supramolecular polyaniline polymer (cPANI). Tight integration of experimental data (circular dichroism, CD, near edge X-ray absorption spectra, NEXAFS, conductive probe atomic force microscopy, CP-AFM) and theoretical [density functional theory, (DFT)] results allows to unfold the nature of the electronic interaction between PANI and 10CSA and to shed light on the physical interactions inducing the chiral character to bulk pristine non-chiral PANI: eventually yielding cPANI. The electropolymerization follows a “wet chemistry” method: electrochemical polymerization of aniline in the co-presence in bulk solution of enantiopure 10-camphorsulfonic acid (10CSA). The latter is exploited as chirality inductor. The method of integration between experimental results with ab-initio theoretical calculations, strongly suggests that the chiral induction exerted by the CSA stems from exchange interaction between CSA and PANI

On the feasibility of a portable electrochemical measuring system for the on-site measurement of cannabinoids

Given the neuroprotective, anti-inflammatory, and analgesic properties of cannabidiol (CBD), many countries have recently legalized the use of fiber-type Cannabis products, including those known as 'Cannabis light'. Nonetheless, in freely commercialized products, it is not uncommon to find Δ9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, in concentrations exceeding the legal limit. To determine whether a product is commercially viable, the THC/CBD ratio is typically analyzed using chromatographic techniques. However, chromatographic techniques have costs, complexity, and response times that prevent their in-situ use, making control actions much more expensive and ineffective. In this work, we report our preliminary activities aimed at verifying the possibility of performing in-situ analysis of cannabinoids in cannabis-derived products using an ad-hoc designed measuring system based on screen-printed electrodes modified with carbon black. The results obtained from preliminary tests comparing fiber cannabis (legal THC concentration) and recreational cannabis (illegal THC concentration) suggest that the proposed system can allow the effective and efficient in-situ analysis of cannabis-derived products

Development of an electrochemical sensor based on carbon black for the detection of cannabidiol in vegetable extracts

A glassy carbon electrode chemically modified with a carbon black coating is proposed here for the rapid and portable determination of cannabidiol (CBD) in a commercial Cannabis seed oil and in fibre-type Cannabis sativa L. leaves. The mechanism of CBD oxidation was studied in relation to simpler phenyl derivatives bearing the same electroactive group, namely resorcinol and 2-methylresorcinol. These molecules also allowed us to determine the best conditions for the electrochemical detection of CBD, as to the pH value and to the best solvent mixture to use. Carbon black was chosen among nanostructured carbon-based materials owing to its outstanding features as an electrode modifier for analyte detection. The performance of the modified electrode was determined by flow injection analyses of standard solutions of CBD, obtaining a linear correlation between the oxidation current and the analyte concentration; the sensor response is characterised by suitable repeatability and reproducibility. The analysis of commercial products by the standard addition method allowed us to ascertain the accuracy of the sensor for the detection of CBD in real samples