Cobalt Complexes with Aminophenolate Ligands: Spin Crossover and Ligand Versatility.

A search for switchable molecules has afforded a family of cobalt complexes featuring derivatives of 2-aminophenol: 4,6-di--butyl aminophenol (HL) and 2-anilino-4,6-di--butyl aminophenol (HL). The heteroleptic cobalt complexes incorporate a Metpa ligand (tpa = tris(2-pyridylmethyl)amine; = 0-3), which involves the methylation of the 6-position of the pyridine ring). Eight members of this family have been synthesized and characterized: [Co(HL)(tpa)](BPh) (), [Co(HL)(Metpa)](BPh) (), [Co(L)(Metpa)](BPh) (), [Co(HL)(Metpa)](BPh) (), [Co(L)(Metpa)](BPh) (), [Co(HL)(tpa)] (BPh)(ClO) (), [Co(L)(tpa)](BPh)(ClO) () and [Co(HL)(Metpa)](BPh) (), where the aminophenol-derived ligands are monoanionic in either the open shell radical iminosemiquinonate (L) or the closed shell protonated aminophenolate (HL).

Synthetic and theoretical study on novel N-ylidic complexes of mercury as new antibacterial agents.

The novel structure of Hg(II) complexes including the pyridinium ylide CHNCHC(O)CH-m-Br (Y) were synthesized and reported in this study. In the first step, the pyridinium salt CHNCHC(O)CH-m-Br (S) was produced by reacting 2,3'-dibromoactophenone and pyridine. then, treatment of S with KCO gave the related pyridinium ylide Y.

Phenotypic-Based Discovery and Exploration of a Resorufin Scaffold with Activity against Mycobacterium tuberculosis.

Tuberculosis remains a leading cause of death by infectious disease. The long treatment regimen and the spread of drug-resistant strains of the causative agent Mycobacterium tuberculosis (Mtb) necessitates the development of new treatment options. In a phenotypic screen, nitrofuran-resorufin conjugate 1 was identified as a potent sub-micromolar inhibitor of whole cell Mtb.

Predicting valence tautomerism in diverse cobalt-dioxolene complexes: elucidation of the role of ligands and solvent.

The ability of molecular switches to reversibly interconvert between different forms promises potential applications at the scale of single molecules up to bulk materials. One type of molecular switch comprises cobalt-dioxolene compounds that exhibit thermally-induced valence tautomerism (VT) interconversions between low spin Co(iii)-catecholate (LS-Co-cat) and high spin Co(ii)-semiquinonate (HS-Co-sq) forms. Two families of these compounds have been investigated for decades but have generally been considered separately: neutral [Co(diox)(sq)(NL)] and cationic [Co(diox)(NL)] complexes (diox = generic dioxolene, NL/NL = bidentate/tetradentate N-donor ancillary ligand).

Anticancer, antioxidant, and antimicrobial studies and molecular docking of a new hexanuclear Zn(II) complex, together with its X-ray crystal analysis.

A new hexanuclear Zn(II) complex with the ligand 2,2'-(piperazine-1,4-diyl)bis(ethan-1-amine), [LZn(OH)][ClO]·3MeOH·7HO, was synthesized. The crystal structure of this complex showed that each Zn atom is in a distorted tetrahedral coordination environment, surrounded by two nitrogen atoms from each ligand and two hydroxide groups, each of which bridges to another Zn atom. The anticancer activities of the ligand and its metal complex against the breast cancer cell line (MCF-7) indicated that the zinc complex had a greater anticancer activity.

Tuning valence tautomerism in a family of dinuclear cobalt complexes incorporating a conjugated bridging bis(dioxolene) ligand with weak communication.

Valence tautomerism (VT) involves the stimulated reversible intramolecular electron transfer between a redox-active metal and ligand. Dinuclear cobalt complexes bridged by bis(dioxolene) ligands can undergo thermally-induced VT with access to {Co-cat-cat-Co}, {Co-cat-SQ-Co} and {Co-SQ-SQ-Co} states (cat = catecholate, SQ˙ = semiquinonate, Co refers to low spin Co, Co refers to high spin Co). The resulting potential for two-step VT interconversions offers increased functionality over mononuclear examples.

Complexation of drug amifampridine with Cu(II), Zn(II) and Cd(II) ions, and its dimerization with the magic of Mn(II) salts. Potential anti-COVID-19 and anticancer activities.

The different behaviors of the drug amifampridine (AMP) against Mn(II), Cu(II), Zn(II) and Cd(II) metal ions, in the presence and absence of tris(2-aminoethyl)amine (tren) was studied. The results showed that AMP successfully coordinates with Cu(II), Zn(II) and Cd(II) metal ions, but interestingly it undergoes an unexpected dimerization through a C-H activation in the presence of different Mn(II) salts. A four-coordinate complex of zinc(II), [Zn(AMP)Cl] (1), a binuclear complex of cadmium(II), [Cd(AMP)Cl] (2), three five-coordinate tren-based metal complexes, [Cu(tren)(AMP)](ClO) (8), [Zn(tren)(AMP)]Cl (9) and [Cd(tren)(AMP)](ClO) (10), three pyridinium salts, [AmpDimer]X (X = Cl, NO, ClO; (3, 4 & 5)), and also two four-coordinate metal complexes with this pyridinium cation, [Zn(AmpDimer)Cl] (6) and [Cd(AmpDimer)Cl] (7), were synthesized.

Controlling Spin Crossover in a Family of Dinuclear Fe(III) Complexes via the Bis(catecholate) Bridging Ligand.

Spin crossover (SCO) complexes can reversibly switch between low spin (LS) and high spin (HS) states, affording possible applications in sensing, displays, and molecular electronics. Dinuclear SCO complexes with access to [LS-LS], [LS-HS], and [HS-HS] states may offer increased levels of functionality. The nature of the SCO interconversion in dinuclear complexes is influenced by the local electronic environment.

Theoretical and solid-state structures of three new macroacyclic Schiff base complexes and the investigation of their anticancer, antioxidant and antibacterial properties.

Three symmetrical macroacyclic Schiff base complexes were prepared from a ligand derived from the condensation reaction of 1,4-bis(2-aminophenyl)piperazine and salicylaldehyde (L) with Cu(ii), Ni(ii) and Co(ii) perchlorates. The ligand and the Schiff base complexes were characterized by elemental analyses, UV-vis, FT-IR and mass spectrometry, with the structure of [CoL] being determined by a single crystal X-ray structural analysis. In this complex, the cobalt is in a distorted trigonal prismatic coordination environment, surrounded by the six donor atoms of the deprotonated hexadentate ligand.

A tris(2-aminoethyl)amine-based zinc complex as a highly water-soluble drug carrier for the anti-COVID-19 drug favipiravir: a joint experimental and theoretical study.

Tris(2-aminoethyl)amine (tren) coordinates to a Zn(II) ion to form the [Zn(tren)] cation that accepts a monodentate favipiravir (FAV) anion. The results of this work show that the FAV anion is capable of binding to the [Zn(tren)] cation through either a nitrogen or an oxygen atom (/-coordination). The energy decomposition analysis shows that, interestingly, both the strength and nature of the bonds between the [Zn(tren)] cation and the /-coordinated FAV anion are almost the same.

Modulating the electronic properties of divalent lanthanoid complexes with subtle ligand tuning.

Five new compounds of formula [Ln(Metpa)](BPh) (Ln = Eu, = 0 (1-Eu), = 2 (2-Eu) and = 3 (3-Eu); Ln = Yb, = 0 (1-Yb) and = 2 (2-Yb); tpa = tris(2-pyridylmethyl)amine, = 0-3 corresponds to successive methylation of the 6-position of the pyridine rings of Metpa) have been synthesized and their structural, photophysical and electrochemical properties investigated. The Ln ions in the five complexes possess cubic coordination geometry and exhibit only small structural differences, due to the lengthening of the Ln-N bonds to accommodate the additional steric bulk associated with increasing methylation of the Metpa ligands. Photophysical studies indicate moderate shifts in absorbance, emission and excitation bands associated with the 4f ↔ 4f5d (Eu) and 4f ↔ 4f5d (Yb) transitions, while electrochemistry reveals modulation of the redox potential of the Ln to Ln oxidation.

Inelastic Neutron Scattering Measurement of the Ground State Tunneling Gap in Tb and Ho Analogues of a Dy Field-Induced Single-Molecule Magnet.

Recent advances in single-molecule magnet (SMM) research have placed great value on interpretation of inelastic neutron scattering (INS) data for rare earth (RE)-containing SMMs. Here, we present the synthesis of several rare earth complexes where combined magnetic and INS studies have been performed, supported by calculations. The reaction of rare earth nitrate salts with 2,2'-bipyridine (2,2'-bpy) and tetrahalocatecholate (XCat, X = Br, Cl) ligands in methanol (MeOH) afforded two new families of compounds [RE(2,2'-bpy)(XCat)(XCatH)(MeOH)] (X = Br and RE = Y, Eu, Gd, Tb, Dy, Ho, Yb for ; X = Cl and RE = Y, Tb, Dy, Ho, and Yb for ).

Modulation of Charge Distribution in Cobalt-α-Diimine Complexes toward Valence Tautomerism.

Valence tautomerism (VT) and spin crossover (SCO) are promising avenues for developing a range of molecular materials for sensing, memory, and optoelectronic applications. However, these phenomena arise only when specific metal-ligand combinations are employed. The underexplored combination of cobalt(II/III) paired with bis((aryl)imino)acenapthene (Ar-BIAN) ligands, which can exist as neutral Ar-BIAN (L), monoanionic radical Ar-BIAN (L), and dianionic Ar-BIAN (L) forms, has potential to afford both VT and SCO.

Elucidation of LMCT Excited States for Lanthanoid Complexes: A Theoretical and Solid-State Experimental Framework.

Photophysical and magnetic properties arising from both ground and excited states of lanthanoid ions are relevant for numerous applications. These properties can be substantially affected, both adversely and beneficially, by ligand-to-metal charge-transfer (LMCT) states. However, probing LMCT states remains a significant challenge in f-block chemistry, particularly in the solid state.

The X-ray crystal structures, molecular docking and biological activities of two novel Cu(II) and Zn(II) complexes with a ligand having a potentially NO donor set and two nitro phenyl rings as pendant arms.

A new ligand (L) containing two nitro phenyl rings as side chains was synthesized. The reaction of this ligand with copper(II) and zinc(II) metal ions gave complexes with different coordination environments. The free ligand and the metal complexes were characterized using a number of spectroscopic methods.

A Convenient DFT-Based Strategy for Predicting Transition Temperatures of Valence Tautomeric Molecular Switches.

The ability to identify promising candidate switchable molecules computationally, prior to synthesis, represents a considerable advance in the development of switchable molecular materials. Even more useful would be the possibility of predicting the switching temperature. Cobalt-dioxolene complexes can exhibit thermally induced valence tautomeric switching between low-spin Co-catecholate and high-spin Co-semiquinonate forms, where the half-temperature () is the temperature at which there are equal amounts of the two tautomers.

Phenotypic characterization of lines overexpressing and in response to abiotic stresses.

Premise: (H-pyrophosphatase) and (-inositol oxygenase) are genes that, when overexpressed individually, enhance the growth and abiotic stress tolerance of plants. We propose that pyramiding and genes will further improve stress tolerance under water-limited and salt-stress conditions.

Methods: and reciprocal crosses were developed and phenomic approaches used to investigate the possible synergy between these genes.

Synthesis and characterisation of fifteen-electron dihalo(carbonyl)tungsten(iii) complexes, Tp*WX(CO) (X = Br, I).

The oxidation of Tp*WI(NCMe)(CO) [Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate] by iodine in refluxing acetonitrile produces paramagnetic Tp*WI(CO), with μ = 1.70 μ and ν(CO) = 1881 cm. The analogous bromo complex, Tp*WBr(CO) (μ = 1.

Understanding the Origin of One- or Two-Step Valence Tautomeric Transitions in Bis(dioxolene)-Bridged Dinuclear Cobalt Complexes.

Valence tautomerism (VT) involves a reversible stimulated intramolecular electron transfer between a redox-active ligand and redox-active metal. Bis(dioxolene)-bridged dinuclear cobalt compounds provide an avenue toward controlled two-step VT interconversions of the form {Co-cat-cat-Co} ⇌ {Co-cat-SQ-Co}⇌{Co-SQ-SQ-Co} (cat = catecholate, SQ = semiquinonate). Design flexibility for dinuclear VT complexes confers an advantage over two-step spin crossover complexes for future applications in devices or materials.

Single-ion anisotropy and exchange coupling in cobalt(ii)-radical complexes: insights from magnetic and studies.

The concurrent effects of single-ion anisotropy and exchange interactions on the electronic structure and magnetization dynamics have been analyzed for a cobalt(ii)-semiquinonate complex. Analogs containing diamagnetic catecholate and tropolonate ligands were employed for comparison of the magnetic behavior and zinc congeners assisted with the spectroscopic characterization and assessment of intermolecular interactions in the cobalt(ii) compounds. Low temperature X-band ( ≈ 9.

Tetraoxolene-bridged rare-earth complexes: a radical-bridged dinuclear Dy single-molecule magnet.

Two families of neutral tetraoxolene-bridged dinuclear rare earth complexes of general formula [((HBpz)RE)(μ-tetraoxolene)] (RE = Y and Dy; HBpz = hydrotris(pyrazolyl)borate; tetraoxolene = fluoranilate (fa; 1-RE) or bromanilate (ba; 2-RE)) have been synthesised and characterised. In each case, the bridging tetraoxolene ligand is in the diamagnetic dianionic form and each rare earth metal centre has two HBpz ligands completing the coordination. Electrochemical studies on the soluble 2-RE family reveal a tetraoxolene-based reversible one-electron reduction.

Valence tautomerism and spin crossover in pyridinophane-cobalt-dioxolene complexes: an experimental and computational study.

Compounds [Co(L-NR)(dbdiox)](BPh) (L-NR = N,N'-di-alkyl-2,11-diaza[3.3]-(2,6)pyridinophane, R = iPr (1a), Et (2a); dbdiox = 3,5-di-tert-butyldioxolene) and [M(L-NiPr)(dbdiox)](BPh) (M = Mn (3a), Fe (4a)) have been synthesized and investigated with a view to possible valence tautomeric (VT) or spin crossover (SCO) interconversions. Single crystal X-ray diffraction data for all compounds at 100 or 130 K indicate trivalent metal cations and di-tert-butylcatecholate (dbcat) dioxolene ligands.

DFT Prediction and Experimental Investigation of Valence Tautomerism in Cobalt-Dioxolene Complexes.

The family of complexes of general formula [Co(Me tpa)(Xdiox)] (tpa = tris(2-pyridylmethyl)amine, n = 0-3 corresponds to successive methylation of the 6-position of the pyridine rings; X = Br, Cl, H, 3,5-Me, 3,5- tBu; diox = dioxolene) was investigated by density functional theory (DFT) calculations to predict the likelihood of valence tautomerism (VT). The OPBE functional with relativistic and solvent corrections allowed accurate reproduction of trends in spin-state energetics, affording the prediction of VT in complex [Co(Metpa)(Brdiox)] (1). One-electron oxidation of neutral precursor [Co(Metpa)(Brcat)] (1) enabled isolation of target compounds 1(PF) and 1(BPh).

Targeted synthesis of a polypyridyl polyoxometalate coordination complex using microwave-assisted reaction conditions.

In this article, we build upon our recent efforts that have focused on demonstrating the value of microwave-assisted synthesis in polyoxometalate (POM) chemistry. Herein, we report for the first time a microwave-assisted approach that enabled the facile preparation and crystallization of a large POM-containing coordination complex. The judicious selection and reaction of a sparingly water-soluble transition-metal-substituted polyanion (TMSP) salt with the tritopic ligand 2,4,6-tris(4-pyridyl)-1,3,5-triazine (TPT) in a mixed solvent system under moderately forcing conditions yields Ba[(BWOCo)(CHN)]·38HO in moderate yield.

Traumatic Childbirth and Its Aftermath: Is There Anything Positive?

Up to 45% of new mothers have reported experiencing birth trauma. For some individuals who have experienced a traumatic event, there can be a positive legacy called posttraumatic growth. Using Tedeschi and Calhoun's Posttraumatic Growth Model as the theoretical framework, the purpose of this pilot study was to determine levels of posttraumatic stress, core beliefs disruption, and posttraumatic growth in women who have experienced traumatic childbirth.