Conformational change induced by binding of Mn ions activates SloR transcription factor in Streptococcus mutans.

Streptococcus mutans, a bacterium commonly found in the human oral cavity, is considered the primary causative agent of dental caries. A key player in the pathophysiology of S. mutans is SloR, a 25-kDa metalloregulatory protein.

Solvatomorphic Diversity in Coordination Compounds of Copper(II) with l-Homoserine and 1,10-Phenanthroline: Syntheses, Crystal Structures and ESR Study.

In this study, we report the syntheses, crystal structures and magnetic properties of ternary copper(II) coordination compounds with l-homoserine (l-Hhser) and 1,10-phenanthroline (phen). Six new coordination compounds were obtained: [Cu(l-hser)(HO)(phen)]SO·5HO (), [Cu(μ-l-hser)(HO)(phen)][Cu(l-hser)(HO)(phen)](SO)∙12HO (), {[Cu(μ-l-hser)(HO)(phen)][Cu(μ-l-hser)(phen)]SO·6HO} (), {[Cu(μ-l-hser)(HO)(phen)]SO·3HO} (), [Cu(l-hser)(HO)(phen)][Cu(l-hser)(CHOH)(phen)]SO·4HO () and {[Cu(l-hser)(CHOH)(phen)][Cu(μ-l-hser)(phen)]SO·5CHOH} () It was shown that slight differences in water content in the synthetic mixtures highly influence the final product, so in some cases, two or three different products were obtained. The compounds were characterized by single-crystal X-ray diffraction and ESR spectroscopy.

The Reversible Electron Transfer Within Stimuli-Responsive Hydrochromic Supramolecular Material Containing Pyridinium Oxime and Hexacyanoferrate (II) Ions.

The structural and electronic features of the stimuli-responsive supramolecular inter-ionic charge-transfer material containing electron accepting -benzylyridinium-4-oxime cation (BPA4) and electron donating hexacyanoferrate (II) are reported. The study of reversible stimuli-induced transformation between hydrated reddish-brown (BPA4)[Fe(CN)]·10HO and anhydrous blue (BPA4)[Fe(CN)] revealed the origin of observed hydrochromic behavior. The comparison of the crystal structures of decahydrate and anhydrous phase showed that subsequent exclusion/inclusion of lattice water molecules induces structural relocation of one BPA4 that alter the donor-to-acceptor charge-transfer states, resulting in chromotropism seen as reversible reddish-brown to blue color changes.

A homochiral tartrate-bridged dinuclear chromium(III) complex anion with a resonance-assisted hydrogen bond for proton conduction.

The synthesis of a homochiral building block based on L-tartrate-chromium(III) complex anions is reported. The dinuclear complex anion, which contains two bridging L-tartrate ligands and one aromatic N-donor ligand coordinated to chromium(III) ions, exhibits a boat conformation in which intramolecular resonance-assisted hydrogen bonding is present. The sodium L-tartrate-chromium(III) compound with the formula Na[Cr(bpy)(L-tart)H]·9HO (1) crystallizes from a methanol-water solution as a high water content material in the monoclinic space group 2.

Structural and dynamical changes of the Streptococcus gordonii metalloregulatory ScaR protein induced by Mn ion binding.

Divalent metal ions are essential micronutrients for many intercellular reactions. Maintaining their homeostasis is necessary for the survival of bacteria. In Streptococcus gordonii, one of the primary colonizers of the tooth surface, the cellular concentration of manganese ions (Mn) is regulated by the manganese-sensing transcriptional factor ScaR which controls the expression of proteins involved in manganese homeostasis.

Light-Induced Intramolecular Electron Transfer in a 1D [CuFe] Coordination Polymer Containing the [Fe(CO)] Core.

A one-dimensional (1D) ladder-like coordination polymer {NH[{Cu(bpy)}(CO)Fe(CO)]·HO} (; bpy = 2,2'-bipyridine) containing [Cu(bpy)(μ-CO)Cu(bpy)] cationic units linked by oxalate groups of [Fe(CO)] building blocks was investigated as a new type of photoactive solid-state system. It exhibits a photocoloration effect when exposed to direct sunlight or UV/vis irradiation. The photochromic properties and mechanism were studied by powder and single-crystal X-ray diffraction, UV/vis diffuse reflectance, IR and electron paramagnetic resonance spectroscopy, magnetization and impedance measurements, and density functional theory calculations.

Improving the molecular spin qubit performance in zirconium MOF composites by mechanochemical dilution and fullerene encapsulation.

Enlarging the quantum coherence times and gaining control over quantum effects in real systems are fundamental for developing quantum technologies. Molecular electron spin qubits are particularly promising candidates for realizing quantum information processing due to their modularity and tunability. Still, there is a constant search for tools to increase their quantum coherence times.

Vanadium(IV) complexes of salicylaldehyde-based furoic acid hydrazones: Synthesis, BSA binding and in vivo antidiabetic potential.

Solution synthesis afforded five novel neutral heteroleptic octahedral paramagnetic mononuclear oxidovanadium(IV) complexes of general composition [VO(bpy)L], where L is a dianionic tridentate ONO-donor hydrazone ligand derived from 2-furoic acid hydrazide and salicylaldehyde and its 5-substituted derivatives. Characterization was carried out by elemental analysis, mass spectrometry, infrared, electron, NMR, and EPR spectroscopy, cyclic voltammetry and conductometry. The molecular and crystal structure of the complex with 5-chloro-salicylaldehyde 2-furoic acid hydrazone (2) was determined.

Tumor selective Ru(III) Schiff bases complexes with strong in vitro activity toward cisplatin-resistant MDA-MB-231 breast cancer cells.

Novel ruthenium(III) complexes of general formula Na[RuCl(L-N,O)] where L denote deprotonated Schiff bases (HL-HL) derived from 5-substituted salicyladehyde and alkylamine (propyl- or butylamine) were prepared and characterized based on elemental analysis, mass spectra, infrared, electron spin/paramagnetic resonance (ESR/EPR) spectroscopy, and cyclovoltammetric study. Optimization of five isomers of complex C1 was done by DFT calculation. The interaction of C1-C3 complexes with DNA (Deoxyribonucleic acid) and BSA (Bovine serum albumin) was investigated by electron spectroscopy and fluorescence quenching.

Low-Dimensional Magnetism in Multivariate Copper/Zinc MOF-74 Materials Formed via Different Mechanochemical Methods.

MOF-74 is an archetypal magnetic metal-organic framework (MOF) family, with metal nodes bridged by 2,5-dioxido-1,4-benzenedicarboxylic acid (Hdobdc) and arranged into one of the simplest representations of the 1D Ising magnetic model. Recently, a novel mechano-synthetic approach opened a pathway toward a series of bimetallic multivariate (1:1) M1M2-MOF-74 materials, with the uniform distribution of metal cations in the oxometallic chains, offering a unique opportunity to investigate low-dimensional magnetism in these heterometallic MOFs. We explore here how different mechanochemical procedures affect the interaction between the metal nodes of the model system of three multivariate copper(II)/zinc(II)-MOF-74 materials, two of which were obtained through a template-controlled procedure, and the third one was obtained by recently developed mechanical MOF-alloying combined with subsequent accelerated aging.

Solvent effects on the crystallization and structure of ternary copper(ii) coordination compounds with l-threonine and 1,10-phenanthroline.

Solution-based and solid-state reactions of copper(ii) compounds, 1,10-phenanthroline and l-threonine were investigated. Eight new ternary coordination compounds were obtained: [Cu(l-Thr)(HO)(phen)]SO∙10HO ( ), [Cu(l-Thr)(HO) (phen)]SO∙4.3HO ( ), {[Cu(-l-Thr)(phen)]SO∙3.

Structural diversity in the coordination compounds of cobalt, nickel and copper with -alkylglycinates: crystallographic and ESR study in the solid state.

Reactions of -methylglycine (HMeGly), -ethylglycine-hydrochloride (HEtGlyCl) and -propylglycine-hydrochloride (HPrGlyCl) with cobalt(ii), nickel(ii) and copper(ii) ions in aqueous solutions resulted in ten new coordination compounds [Co(MeGly)(HO)] (1), [{Co(MeGly)}(μ-OH)]·2HO (1d), [Cu(MeGly)(HO)] (2α), [Co(EtGly)(HO)] (3), [Ni(EtGly)(HO)] (4), [Cu(μ-EtGly)] (5p), [Co(PrGly)(HO)] (6), [Ni(PrGly)(HO)] (7), and two polymorphs of [Cu(PrGly)(HO)] (8α and 8β). Compounds were characterized by single-crystal and powder X-ray diffraction, infrared spectroscopy, thermal analysis and X-band electron spin resonance (ESR) spectroscopy. These studies revealed a wide range of structural types including monomeric, dimeric and polymeric architectures, as well as different polymorphs.

A mononuclear iron(III) complex with unusual changes of color and magneto-structural properties with temperature: synthesis, structure, magnetization, multi-frequency ESR and DFT study.

From the reaction of 2-hydroxy-6-methylpyridine (L) with iron(II) tetrafluoroborate, a new mononuclear iron(III) octahedral complex [FeL](BF) has been isolated. The color of the complex reversibly changed from red at room temperature to yellow-orange at the liquid nitrogen temperature. Magnetization measurements indicate that iron(III) in [FeL](BF) is in a high-spin state = 5/2, from room temperature to 1.

Controlling the Polymorphism and Topology Transformation in Porphyrinic Zirconium Metal-Organic Frameworks via Mechanochemistry.

Tetratopic porphyrin-based metal-organic frameworks (MOFs) represent a particularly interesting subclass of zirconium MOFs due to the occurrence of several divergent topologies. Control over the target topology is a demanding task, and reports often show products containing phase contamination. We demonstrate how mechanochemistry can be exploited for controlling the polymorphism in 12-coordinated porphyrinic zirconium MOFs, obtaining pure hexagonal PCN-223 and cubic MOF-525 phases in 20-60 min of milling.

Cobalt, nickel and copper complexes with glycinamide: structural insights and magnetic properties.

Ten new compounds of Co, Ni and Cu with glycinamide (HL = glycinamide): [Co(HO)(HL)]Cl (1a), [Co(HO)(HL)]BrCl (1b), [Co(HO)(HL)]I (1c), [Ni(HO)(HL)]Cl (2a), [Ni(HO)(HL)]BrCl (2b), [Ni(HO)(HL)]I (low and room temperature polymorph, 2c and 2c), [CuCl(HL)] (3a), [CuBrCl(HL)] (3b) and {[Cu(HL)][CuI]} (3c), as well as glycinamide hydroiodide (HLI) and a new polymorph of glycinamide hydrochloride (β-HLCl) were prepared and characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermal analysis (TG/DTA) and ESR spectroscopy. 1a, 1b, 2a and 2b are isostructural, as well as 1c and 2c, while the Cu compounds (3a-c) have entirely different molecular structures. All investigated compounds are mononuclear with exception of the 1D coordination polymer 3c.

Solvent-free copper-catalyzed click chemistry for the synthesis of -heterocyclic hybrids based on quinoline and 1,2,3-triazole.

Copper-catalyzed mechanochemical click reactions using Cu(II), Cu(I) and Cu(0) catalysts have been successfully implemented to provide novel 6-phenyl-2-(trifluoromethyl)quinolines with a phenyl-1,2,3-triazole moiety at O-4 of the quinoline core. Milling procedures proved to be significantly more efficient than the corresponding solution reactions, with up to a 15-fold gain in yield. Efficiency of both solution and milling procedures depended on the -substituent in the azide reactant, resulting in H < Cl < Br < I reactivity bias.

Magnetostructural Characterization of Oxalamide Dihalo-Bridged Copper Dimers: Intra- and Interdimer Interactions Studied by Single-Crystal Electron Spin Resonance Spectroscopy.

Detailed single-crystal electron spin resonance (ESR) analysis of oxalamide complexes with halogen-bridged copper dimers, supported by X-ray, magnetic susceptibility, and powder ESR studies, is reported. Four complexes with two different ligands are synthesized: [CuL (μ-X)] and [CuL (μ-X)] , for which L =N-(l-alanine methyl ester)-N'-[(2-pyridine-2-yl)methyl]oxalamide and L =N-(l-valine methyl ester)-N'-[(2-pyridine-2-yl)methyl]oxalamide, for which X=Cl or Br. X-ray analysis shows that the geometry at each copper(II) ion is square pyramidal, whereas two pyramids share one base-to-apex edge with parallel basal planes.

In Situ Monitoring of the Mechanosynthesis of the Archetypal Metal-Organic Framework HKUST-1: Effect of Liquid Additives on the Milling Reactivity.

We have applied in situ monitoring of mechanochemical reactions by high-energy synchrotron powder X-ray diffraction to study the role of liquid additives on the mechanochemical synthesis of the archetypal metal-organic framework (MOF) HKUST-1, which was one of the first and is still among the most widely investigated MOF materials to be synthesized by solvent-free procedures. It is shown here how the kinetics and mechanisms of the mechanochemical synthesis of HKUST-1 can be influenced by milling conditions and additives, yielding on occasion two new and previously undetected intermediate phases containing a mononuclear copper core, and that finally rearrange to form the HKUST-1 architecture. On the basis of in situ data, we were able to tune and direct the milling reactions toward the formation of these intermediates, which were isolated and characterized by spectroscopic and structural means and their magnetic properties compared to those of HKUST-1.

Magnetic order in a novel 3D oxalate-based coordination polymer {[Cu(bpy)3][Mn2(C2O4)3]·H2O}n.

A heterometallic coordination polymer {[Cu(bpy)3][Mn2(C2O4)3]·H2O}n (1; bpy = 2,2'-bipyridine) was synthesized using a building-block approach and characterized by IR spectroscopy, single-crystal X-ray diffraction, magnetization measurement, and X-band ESR spectroscopy both on a single crystal and a polycrystalline sample. The molecular structure of 1 is made of a three-dimensional (3D) anionic network [Mn2(C2O4)3]n(2n-) and tris-chelated cations [Cu(bpy)3](2+) occupying the vacancies of the framework. In compound 1 magnetic order is confirmed below 12.

Crystal structures and magnetic properties of a set of dihalo-bridged oxalamidato copper(II) dimers.

A set of four copper(ii) complexes, and (X = Cl, Br; = N-(l-leucine methyl ester)-N'-((2-pyridin-2-yl)methyl)oxalamide and = N-benzyl-N'-((2-pyridin-2-yl)methyl)oxalamide), have been synthesized and characterized by X-ray structural analysis, electron paramagnetic resonance (EPR) spectroscopy on single crystals and by SQUID magnetization measurements. X-ray diffraction studies show one-dimensional hydrogen bonded networks of dimeric copper(ii)-complexes bridged by two halide ions and with the two metal centers 3.44-3.

Single crystals of DPPH grown from diethyl ether and carbon disulfide solutions - crystal structures, IR, EPR and magnetization studies.

Single crystals of the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) obtained from diethyl ether (ether) and carbon disulfide (CS₂) were characterized by the X-ray diffraction, IR, EPR and SQUID magnetization techniques. The X-ray structural analysis and IR spectra showed that the DPPH form crystallized from ether (DPPH1) is solvent free, whereas that one obtained from CS₂ (DPPH2) is a solvate of the composition 4DPPH·CS₂. Principal values of the g-tensor were estimated by the X-band EPR spectroscopy at room and low (10 K) temperatures.