3D Printed Voltammetric Sensor Modified with an Fe(III)-Cluster for the Enzyme-Free Determination of Glucose in Sweat

In this work, a 3D printed sensor modified with a water-stable complex of Fe(III) basic benzoate is presented for the voltammetric detection of glucose (GLU) in acidic epidermal skin conditions. The GLU sensor was produced by the drop-casting of Fe(III)-cluster ethanolic mixture on the surface of a 3D printed electrode fabricated by a carbon black loaded polylactic acid filament. The oxidation of GLU was electrocatalyzed by Fe(III), which was electrochemically generated in-situ by the Fe(III)-cluster precursor. The GLU determination was carried out by differential pulse voltammetry without the interference from common electroactive metabolites presented in sweat (such as urea, uric acid, and lactic acid), offering a limit of detection of 4.3 μmol L-1. The exceptional electrochemical performance of [Fe3O(PhCO2)6(H2O)3]∙PhCO2 combined with 3D printing technology forms an innovative and low-cost enzyme-free sensor suitable for noninvasive applications, opening the way for integrated 3D printed wearable biodevices.

Trinuclear and tetranuclear iron(III) complexes with fenamates: Structure and biological profile

The interaction of FeCl₃ with the fenamate non-steroidal anti-inflammatory drugs has led to the formation and isolation of trinuclear iron(III) complexes, while in the presence of the nitrogen-donors 2,2'-bipyridine or pyridine tetranuclear iron(III) complexes were derived. The five resultant complexes were characterized by diverse techniques (including infrared, electronic and Mössbauer spectroscopy) and their crystal structures were determined by single-crystal X-ray crystallography. These complexes are the first structurally characterized Fe(III)-fenamato complexes. The complexes were evaluated for their ability to scavenge in vitro free radicals such as hydroxyl, 1,1-diphenyl-2-picrylhydrazyl and 2,2΄-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid). The in vitro binding affinity of the complexes to calf-thymus (CT) DNA was examined and their interaction with serum albumins was also investigated. In total, the complexes present promising activity against the radicals tested, and they may bind tightly to CT DNA possibly via intercalation and reversibly to serum albumins.

Half-Integer Spin Triangles: Old Dogs, New Tricks

Spin triangles, that is, triangular complexes of half-integer spins, are the oldest molecular nanomagnets (MNMs). Their magnetic properties have been studied long before molecular magnetism was delineated as a research field. This Review presents the history of their study, with references to the parallel development of new experimental investigations and new theoretical ideas used for their interpretation. It then presents an indicative list of spin-triangle families to illustrate their chemical diversity. Finally, it makes reference to recent developments in terms of theoretical ideas and new phenomena, as well as to the relevance of spin triangles to spintronic devices and new physics.

Noncollinear Two-Component Quasirelativistic Description of Spin Interactions in Exchange-Coupled Systems. Mapping Generalized Broken-Symmetry States to Effective Spin Hamiltonians

We provide a consistent mapping of noncollinear two-component quasirelativistic DFT energies with appropriate orientations of localized spinor quantization axes for multinuclear exchange-coupled transition-metal complexes onto an uncoupled anisotropic effective spin Hamiltonian. This provides access to the full exchange interaction tensor between the centers of spin-coupled systems in a consistent way. The proposed methodology may be best viewed as a generalized broken-symmetry density functional theory approach (gBS-DFT). While the calculations provided are limited to trinuclear systems ([M₃O(OOCH)₆(H₂O)₃]⁺, where M = Cr(III), Mn(III), Fe(III)) with C₃ symmetry, the method provides a general framework that is extendable to arbitrary systems. It offers an alternative to previous approaches to single-ion zero-field splittings, and it provides access to the less often examined antisymmetric Dzyaloshinskii-Moriya exchange interaction. Spin-orbit coupling is included self-consistently. This will be of particular importance for complexes involving 4d or 5d transition metal centers or possibly also for f-block elements, where a perturbational treatment of spin-orbit coupling may not be valid anymore. While a comparison with experimental data was indirect due to simplifications in the chosen model structures, the agreement obtained indicates the essential soundness of the presented approach.

Interactions between H-bonded [CuII3(μ3-OH)] triangles; a combined magnetic susceptibility and EPR study

X-band EPR spectroscopy and magnetic susceptibility studies elucidate the magnetic exchange scheme within a triangular CuII3(μ₃-OH) complex and the intermolecular dipolar interactions between two H-bonded CuII3(μ₃-OH) units.

Towards ionic liquids with tailored magnetic properties: bmim+ salts of ferro- and antiferromagnetic CuII3 triangles

With proper selection of counteraction and pH control, CuII3-pyrazolate anions can form a ferromagnetic low-melting solid, or an antiferromagnetic viscous paste.

Solvothermal synthesis of discrete cages and extended networks comprising {Cr(iii)3O(O2CR)3(oxime)3}2− (R = H, CH3, C(CH3)3, C14H9) building blocks

We present the solvothermal synthesis, structural and magnetic characterisation of a family of Cr(iii) cages and extended networks comprising {Cr(iii)₃O(O₂CR₁)₃(R₂-sao)}²⁻ (R₁ = H, CH₃, C(CH₃)₃, C₁₄H₉; R₂ = Me, Ph, ^tBu, C₁₀H₆) building blocks.

Electronic Structure of a Mixed-Metal Fluoride-Centered Triangle Complex: A Potential Qubit Component

A novel fluoride-centered triangular-bridged carboxylate complex, [Ni2Cr(μ3-F)(O2C(t)Bu)6(HO2C(t)Bu)3] (1), is reported. Simple postsynthetic substitution of the terminal pivalic acids in 1 with pyridine and 4-methylpyridine led to the isolation of [Ni2Cr(μ3-F)(O2C(t)Bu)6(C5H5N)3] (2) and [Ni2Cr(μ3-F)(O2C(t)Bu)6((4-CH3)C5H4N)3] (3). Structural and magnetic characterizations carried out on the series reveal a dominating antiferromagnetic interaction between the nickel and chromium centers leading to an S = (1)/2 ground state with a very unusual value of geff = 2.48.

A pyrazolate-supported Fe(3)(mu(3)-O) core: structural, spectroscopic, electrochemical, and magnetic study

A comparison is made between the structural, spectroscopic, electrochemical, and magnetic properties of pyrazolate versus carboxylate complexes [Fe3(mu3(mu3O)(mu-LL)6Cl3]2- containing the Fe3(mu3-O)-motif. While the Fe3(mu3-O)-cores are structurally indistinguishable in the two types of complexes, their magnetic properties deviate from the expected values as a result of a through-pyrazole contribution to the overall antiferromagnetic exchange with J1/hc = -80.1 cm(-1) and J2/hc = -72.4 cm(-1), or J1/hc = 70.6 cm(-1) and J2/hc = -80.8 cm(-1), (Hex = -J1(S1S2 + S2S3) - J2S1S3). The magnetic properties of the pyrazolate complexes are further tuned by an antisymmetric exchange interaction term.

An “S”-shaped pentanuclear CuII cluster derived from the metal-assisted hydrolysis of pyCOpyCOpy: structural, magnetic and spectroscopic studies

Reaction of [Cu2(O2CMe)4(H2O)2] with 2,6-di-(2-pyridylcarbonyl)-pyridine (pyCOpyCOpy or dpcp) in MeCN-H2O 10:1, led to the pentanuclear copper(II) complex [Cu5(O2CMe)6{pyC(O)(OH)pyC(O)(OH)py}2] () which crystallizes in the triclinic P1 space group. The copper(II) atoms are arranged in an "S"-shaped configuration, and are bridged by the doubly deprotonated bis(gem-diol) form of the ligand, pyC(O)(OH)pyC(O)(OH)py2-. Magnetic susceptibility data indicate the interplay of both ferro- and antiferromagnetic intramolecular interactions stabilizing an S=3/2 ground state. Fitting of the data according to a next-nearest-neighbour model {H=-[J1(S1S2+S1'S2')+J2(S2S3+S3'S2')+J3(S1S3+S3'S1')+J4(S2S2')]} yields exchange coupling constants J1=+39.7 cm(-1), J2=-15.9 cm(-1), J3=-8.3 cm(-1) and J4=+4.3 cm(-1), leading to an S=3/2 ground state. X-Band EPR spectroscopy indicates a zero-field splitting of the ground state with |D3/2|=0.38 cm(-1).