MnII Complexes Research Articles

Ceric Ammonium Nitrate Oxidation of a MnII Complex Generates a Bis(μ-oxo)dimanganese(IV,IV) Product via a MnIV-Oxo Intermediate.

The oxidation of manganese complexes using ceric ammonium nitrate (CAN) is often complicated by the fact that cerium(IV) can serve as both an oxidant and a Lewis acid. In this work, we explore the reaction of CAN with the MnII complex [MnII(OTf)(DMMN4py)](OTf) (DMMN4py = N,N-bis(4-methoxy-3,5-dimethyl-2-pyridylmethyl)-N-bis(2-pyridyl)methylamine). We chose this complex as multiple oxidation products, including oxomanganese(IV) and bis(μ-oxo)dimanganese(III,IV) complexes, have previously been reported. We envisioned that knowledge of the spectral properties of these intermediates would aid in understanding the potential complexities of CAN oxidation reactions. The oxidation of [MnII(OTf)(DMMN4py)](OTf) with 2.0 equiv CAN in 9:1 (v/v) MeCN:H2O at 25 °C transiently forms the MnIV-oxo complex, but this species is formed in low yields and is unstable. The MnIV-oxo complex evolves to a new intermediate that had not been previously observed. At lower temperatures, the formation of this new intermediate is preceded by formation of the previously reported bis(μ-oxo)dimanganese(III,IV) complex. EPR and X-ray absorption experiments for the new intermediate provide strong evidence for its formulation as [MnIVMnIV(μ-O)2(DMMN4py)2]4+. This work establishes dinuclear MnIVMnIV species as products that must be considered in CAN oxidation reactions of MnII complexes and shows that both mononuclear MnIV-oxo and dinuclear MnIIIMnIV complexes can be intermediates in such reactions.

Family of Quasi-Isotropic MnII and Mn2II Complexes Exhibiting Slow Relaxation of the Magnetization.

Slow relaxation of magnetization has been studied for a family of mononuclear MnII complexes and one ferromagnetic dinuclear system, all of them presenting very weak anisotropy. Complexes with formula [{NiL1Mn(H2O)2(MeOH)}{NiL1}2](ClO4)2 (1), [Mn{NiL1}2](ClO4)2 (2), [Mn{NiL2}2](ClO4)2 (RR-L22-, 3RR, SS-L22-, 3SS), [Mn{NiL3}2](ClO4)2 (RR-L32-, 4RR, SS-L32-, 4SS) and (μ1,1-N3)2[Ni2Mn2(L1)2(N3)2] (5) are derived from compartmental Schiff bases, in which the NiII environment is square planar and thus diamagnetic. All of the systems have been structurally and magnetically characterized. Zero field splitting (D) values for the MnII cations have been obtained from EPR spectroscopy and NEVPT2 calculations. The slow relaxation of the magnetization for 1-5 has been studied by means of ac magnetometry and rationalized on the basis of their low, but not zero, anisotropy, providing the first example of a polynuclear MnII complex, with S = 5 ground state, exhibiting slow relaxation.

Design, synthesis, structural characterization, molecular docking, antibacterial, anticancer activities, and density functional theory calculations of novel MnII, CoII, NiII, and CuII complexes based on pyrazolone-sulfadiazine azo-dye ligand

This study was designed to prepare novel metal chelates obtained from 4-((3-methyl-5-oxo-1-phenyl-pyrazol-4-yl)diazenyl)-N-(pyrimidin-2-yl) benzenesulfon amide (MPSA). They are characterized through CHN-analysis, spectroscopic (1HNMR, FT-IR, UV–Vis), mass, and TG analysis. The FT-IR and UV–visible spectra were related to the computed results and showed good conformity. The mass spectra determined that the ligand's molecular weight and chelates matched well with the found m/z values. The optimization for the studied chelates indicated the formation of distorted octahedral geometry for the prepared chelates. The B3LYP/6–311G** level for the free ligand and the B3LYP/6–311G**-LANL2DZ functional level for the metal ions in chelates were used in density functional theory (DFT) calculations. The results showed that the DFT computations match those of the experimental ones. Using the B3LYP/6–31G(d,p) basis set, TD-DFT/PCM was applied to determine the electronic spectral transitions of the produced compounds. Also, B3LYP/6–31G(d,p) has been utilized to implement the vibrational wavenumbers, and the results are reliable with the innovative ones. The antimicrobial activities of the compounds were experimentally established against a subsection of G+ and G- bacteria. The anticancer activities of the ligand were examined against some cell lines. The MCF7 cell line had the highest activity and was subjected to the anticancer effect of the ligand and its chelates. The cytotoxicity on normal cells was estimated against normal HSF cell lines. The outcomes demonstrated that chelates enhanced their cytotoxic and anticancer properties. Molecular docking mechanisms were done to establish how the obtained substances attach to the breast cancer-targeted protein binding sites,

Synthesis, crystal structure and photophysical properties of a dinuclear MnII complex with 6-(di-ethyl-amino)-4-phenyl-2-(pyridin-2-yl)quinoline.

A new quinoline derivative, namely, 6-(di-ethyl-amino)-4-phenyl-2-(pyridin-2-yl)quinoline, C24H23N3 (QP), and its MnII complex aqua-1κO-di-μ-chlorido-1:2κ4 Cl:Cl-di-chlorido-1κCl,2κCl-bis-[6-(di-ethyl-amino)-4-phenyl-2-(pyridin-2-yl)quinoline]-1κ2 N 1,N 2;2κ2 N 1,N 2-dimanganese(II), [Mn2Cl4(C24H23N3)2(H2O)] (MnQP), were synthesized. Their compositions have been determined with ESI-MS, IR, and 1H NMR spectroscopy. The crystal-structure determination of MnQP revealed a dinuclear complex with a central four-membered Mn2Cl2 ring. Both MnII atoms bind to an additional Cl atom and to two N atoms of the QP ligand. One MnII atom expands its coordination sphere with an extra water mol-ecule, resulting in a distorted octa-hedral shape. The second MnII atom shows a distorted trigonal-bipyramidal shape. The UV-vis absorption and emission spectra of the examined compounds were studied. Furthermore, when investigating the aggregation-induced emission (AIE) properties, it was found that the fluorescent color changes from blue to green and eventually becomes yellow as the fraction of water in the THF/water mixture increases from 0% to 99%. In particular, these color and intensity changes are most pronounced at a water fraction of 60%. The crystal structure contains disordered solvent mol-ecules, which could not be modeled. The SQUEEZE procedure [Spek (2015 ▸). Acta Cryst. C71, 9-18] was used to obtain information on the type and qu-antity of solvent mol-ecules, which resulted in 44 electrons in a void volume of 274 Å3, corresponding to approximately 1.7 mol-ecules of ethanol in the unit cell. These ethanol mol-ecules are not considered in the given chemical formula and other crystal data.

Synthesis, crystal structure and Hirshfeld surface analysis of Mn(II) coordination compounds with ONO-donor ligands derived from ampyrone

Four manganese(II) coordination compounds, [Mn2(L1)2(NCS)2(MeOH)2] (1) [Mn(HL2)2(NCS)2(MeOH)2] (2) [Mn2(L3)2(NCS)2(MeOH)2] (3) and [Mn(HL3)2(NCS)2(MeOH)2] (4) have been synthesized from the reaction of MnCl2·4H2O, KSCN and Schiff base ligands derived from 4-aminoantipyrine (HL1= (E)-4-((2-hydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one; HL2 = (E)-4-((2-hydroxy-3-methoxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one and HL3 = (E)-4-((5-bromo-2-hydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one) in methanol and the products have been characterized with single crystal X-ray diffraction (SC-XRD). The detailed studies involve the synthesis, crystal structure, FT-IR spectroscopy, UV–Vis spectroscopy, bond sum valence calculations, elemental and Hirshfeld surface analyses. In the case of 1 and 3, the phenolate bridged dinuclear MnII complexes are formed by chelating two Schiff base ligands, two thiocyanates and two methanol molecules and two crystallographically equivalent MnII ions are connected together by phenolate oxygen with the Mn···Mn distance of 3.1618(4) (in 1) and 3.1910(6) Å (in 3). In the case of 2 and 4, the octahedral coordination geometry of the MnII center in these mononuclear species is formed by chelating two Schiff base ligands, two thiocyanates and two methanol molecules. The presence of intermolecular hydrogen bond in 2 leads to the formation of molecular chains within the layers. Also, the presence of efficient π···π interactions between pyrazolone and phenyl rings and intermolecular hydrogen bonding in 4 lead to the formation of molecular chains within the layers. All of the intermolecular and intramolecular interactions have been studied by Hirshfeld surface analyses.

Three coordinated first row-transition metal complexes, [M{N(SiMe3)2}3]−1/0: Structure, bonding, and magnetic properties

Structure, bonding, and magnetic properties of [M{N(SiMe3)2}3]−1/0 (M = first row-transition metal, Sc-Cu in + 2/+3 oxidation state) complexes are studied. The atoms in molecules (AIM) analysis shows that non-covalent interactions between the methyl hydrogens are prevalent. Energy decomposition analysis coupled with natural orbital for chemical valence (EDA-NOCV) analysis shows that the ligand is bonded to the metal ions through σ and π bonding. In addition, the reasonable contribution from the dispersion interaction supports van der Waals' type of interaction. The highest value of magnetic anisotropy (D) is calculated in the NiII complex with a value of −382.945 (−234.145) cm−1 at the CASSCF (NEVPT2) level of theory. It is significantly higher than the previously reported values of −14.644 (−15.631) and −63.691 (−64.000) cm−1 in similar CrII and MnIII complexes, respectively. Ab Initio Ligand Field Theory (AILFT) is utilized to calculate the splitting of the d-orbitals in all the metal complexes. In the NiII complexes, the blocking barrier (Ueff) is found to be 127 cm−1. Thus, it has a high potential to be utilized as a single ion magnet (SIM).

A one-pot reduction route to bimetallic manganese 1,8-naphthyridine complexes.

Reaction of the dinucleating ligand 2,7-bis(6-methyl-2-pyridyl)-1,8-naphthyridine (MeL) with the MnI and MnII precursors MnBr(CO)5 and MnCl2 resulted in the formation of the monometallic complexes [MnBr(CO)3(MeL)] (1) and [MnCl2(MeL)] (3). In both cases, formation of bimetallic manganese complexes could be achieved by reduction with KC8, yielding the carbonyl-bridged complex [Mn2(CO)6(MeL)] (2) and the helicate complex [Mn2(MeL)2] (4), respectively. EPR results demonstrate that 4 represents a novel, weakly antiferromagnetically coupled homovalent dimer (J = -0.85 cm-1). The two formally Mn0 ions are both high spin (S = 3/2) and exhibit a zero-field splitting of ≈1 cm-1, suggesting reduction of the complex is substantially ligand centered, and may be better described as a MnII complex coupled to two open shell singlet ligands [MnII2(MeL2-)2]. X-ray crystallography, UV-Vis spectroscopy and DFT analysis support this finding.

Equatorial restriction of the photoinduced Jahn-Teller switch in Mn(iii)-cyclam complexes.

Ultrafast transient absorption spectra were recorded for solutions of [MnIII(cyclam)(H2O)(OTf)][OTf]2 (cyclam = 1,4,8,11-tetraazacyclotetradecane and OTf = trifluoromethanesulfonate) in water to explore the possibility to restrict the equatorial expansion following photoexcitation of the dxy ← dz2 electronic transition, often resulting in a switch from axial to equatorial Jahn-Teller distortion in MnIII complexes. Strong oscillations were observed in the excited state absorption signal and were attributed to an excited state wavepacket. The structural rigidity of the cyclam ligand causes a complex reaction coordinate with frequencies of 333, 368, 454 and 517 cm-1, and a significantly shorter compressed-state lifetime compared to other MnIII complexes with less restricted equatorial ligands. Complementary density functional theory quantum chemistry calculations indicate a switch from an axially elongated to a compressed structure in the first excited quintet state Q1, which is accompanied by a modulation of the axial tilt angle. Computed harmonic frequencies for the axial stretching mode (∼379 cm-1) and the equatorial expansions (∼410 and 503 cm-1) of the Q1 state agree well with the observed coherences and indicate that the axial bond length contraction is significantly larger than the equatorial expansion, which implies a successful restriction of the wavepacket motion. The weak oscillation observed around 517 cm-1 is assigned to a see-saw motion of the axial tilt (predicted ∼610 cm-1). The results provide insights into the structural perturbations to the molecular evolution along excited state potential energy surfaces of MnIII octahedral complexes and can be used to guide the synthesis of optically controlled MnIII-based single-molecule magnets.

Syntheses and magnetic properties of a bis-bidentate nitronyl nitroxide radical based on triazolopyrimidine and its metal complexes.

A novel bis-bidentate nitronyl nitroxide radical based on triazolopyrimidine, NIT-2-TrzPm (NIT-2-TrzPm = (2-(2'-triazolopyrimidine)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxy-3-oxide)) and six new transition metal complexes of this ligand, namely [M(hfac)2(NIT-2-TrzPm)]·CH2Cl2 (M = Mn (1Mn) and Co (2Co)), [M(hfac)2]2(NIT-2-TrzPm) (M = Mn (3Mn) and Co (4Co)), [Mn(NIT-2-TrzPm)2(MeOH)2](ClO4)2·MeOH (5Mn), and [Co(NIT-2-TrzPm)2(MeOH)2]2(ClO4)4·4MeOH (6Co) were prepared and characterized structurally and magnetically. These complexes can be selectively synthesized by controlling the reaction ratio of M(hfac)2·2H2O to the radical ligand (for 1Mn to 4Co) or using metal perchlorates as the starting materials (for 5Mn and 6Co). Single crystal X-ray crystallographic analyses confirmed that 1Mn and 2Co are isostructural 3d-2p MII-radical complexes, in which the NIT-2-TrzPm radical acts as a terminal bidentate ligand chelating to one 3d ion, while 3Mn and 4Co are isostructural 3d-2p-3d MII-radical-MII complexes with the NIT-2-TrzPm radical acting as a bridging ligand between two 3d ions. For complexes 5Mn and 6Co, two NIT-2-TrzPm ligands from the equatorial positions coordinate with the metal center to form the 2p-3d-2p structures with the axial positions occupied by two methanol molecules. Magnetic analysis on the MnII complexes revealed the existence of a strong antiferromagnetic interaction between the MnII and the NIT radical spin, while weak ferromagnetic coupling for Mn⋯Mn and Rad⋯Rad in the Mn-NIT-Mn and Rad-Mn-Rad spins was confirmed. Interestingly, although the NIT-bridged complexes 3Mn and 4Co possess significantly different magnetic anisotropy, field-induced slow magnetic relaxation can be observed in both complexes, which was assigned to the phonon bottleneck effect for 3Mn and field-induced SMM behavior for 4Co. To the best of our knowledge, 3Mn is the first example of the NIT-bridged binuclear MnII complex undergoing slow magnetic relaxation.

4f → 3d sensitization: a luminescent EuII-MnII heteronuclear complex with a near-unity quantum yield.

A new heteronuclear EuII-MnII complex [Eu(N2O6)]MnBr4 (N2O6 = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) is designed and synthesized, which shows an intense green emission from MnII with a near-unity photoluminescence quantum yield. Measurement of excited-state dynamics demonstrated the sensitization process from EuII to MnII, which represents the first example of f → d molecular sensitization. Due to the large optical absorption cross-section of the EuII center, [Eu(N2O6)]MnBr4 shows an emission intensity 7 to 2500 times stronger than that of the SrII-MnII control complex [Sr(N2O6)]MnBr4 upon the excitation of near ultraviolet to blue light.

Double dicyanamide decorated double phenoxide bridged MnIII dimer with single-molecule magnetic behaviour and bio-catalytic activity

Herein, we report the magnetic properties and bio-catalytic activity of a flying bee-like double phenoxido bridged dinuclear MnIII-Schiff base complex decorated with double dicyanamide (dca−) ligands and formulated as: [Mn2(L)2(dca)2] (1) (where H2L = 2,2′-((1E,1′E)-(ethane-1,2-diylbis(azanylylidene))-bis(ethan-1-yl-ylidene))diphenol). The complex has been synthesised by one-pot stepwise reaction of the tetradentate Schiff’s base ligand H2L with MnCl2 and dca− at 1:1:2 ratio under aerobic conditions. It has been characterized by single crystal X-ray diffraction (SC-XRD) and spectroscopic techniques. Complex 1 contains two MnIII ions connected by a double phenoxido bridge in an octahedral geometry and terminal dca− ligands. The dimers are connected to other dimers through both hydrogen bonding and π-interactions to form an extended supramolecular network. The present study reveals that in presence of tetradentate Schiff base ligands, the use of a 1:2 Mn:dca− ratio leads to formation of a dimeric MnIII complex in contrast to the discrete mononuclear complexes or 1D structures previously obtained for the Mn:dca− ratio of 1:1. The magnetic study indicates that the dimeric MnIII complex shows a negligible MnIII–MnIII interaction and a large anisotropy. The AC susceptibility measurements indicate that complex 1 behaves as a field-induced single-molecule magnet (SMM), with a high energy barrier of 73(4)K. The study of model catechol oxidase-like enzyme activity of complex 1 indicates that the dimeric MnIII complex acts as an active catalyst (kcat = 34.94 h−1) in the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) in presence of aerial O2 in acetonitrile medium.

Manganese(II) complexes of 1,1′-bis[(pyridin-2-yl)methyl)]-2,2′-bipiperidine (PYBP): Synthesis, structure, catalytic properties in alkene epoxidation with hydrogen peroxide, and related mechanistic studies

Several manganese(II) complexes with the stereoisomers of ligand PYBP (1,1′-bis[(pyridin-2-yl)methyl]-2,2′-bipiperidine) and different anions were prepared and characterized by X-ray diffractometry. Complex [MnII(rac-PYBP)]2+ (1) was found to be an efficient catalyst of alkene epoxidation by hydrogen peroxide in the presence of acetic acid in acetonitrile at room temperature. Cyclooctene was converted to its epoxide with up to 91 % yield, 99.6 % selectivity, and the turnover number of 180 within 5 min. Fast epoxidations of cyclohexene, 1-decene, styrene, and cis-stilbene were also achieved. Isomeric complex [MnII(meso-PYBP)]2+ (2) was catalytically inactive under the same experimental conditions. Stopped-flow spectrophotometry and freeze-quenched EPR spectra show that complex 2 is not oxidized by H2O2 in the presence of acetic acid (AcOH) but instead undergoes partial ligand protonation and liberation of the Mn2+ cations due to the relatively poor chelating ability of ligand meso-PYBP. The rac-PYBP isomer acts as a better ligand and retains the coordinated Mn center when complex 1 is treated with the H2O2/AcOH mixture in acetonitrile solution yielding a mixture of intensely colored intermediates likely involving MnIII, MnIV, and MnV complexes. Magnetic susceptibility measurements, UV–vis and EPR spectra suggest that dinuclear complexes [MnIII2(μ-O)(μ-OAc)(rac-PYBP)2]3+ and [MnIIIMnIV(μ-O)2(rac-PYBP)2]3+ gradually accumulate in the reaction mixture as inactivated states of the catalyst. Complex 1 also causes fast decomposition of hydrogen peroxide into O2 gas and H2O, which competes with the epoxidation of alkenes and requires gradual addition of H2O2 for its efficient use. The catalytic activity of complex 1 is strongly influenced by its counterions and decreases in order ClO4− ≈ SbF6− > NO3– > Cl− indicating that labile ligands in the coordination sphere of Mn are required for the activation of H2O2.

Two novel Anderson-type polyoxometalate based MnIII complexes constructed from pyrene derivatives: Synthesis, photophysical, and electrochemical properties

Symmetrical chloride-functionalized Anderson type POM afterwards used as a building block for onward POM post-functionalization with organic pyrene compounds and two novel organic–inorganic hybrid pyrene-POM compounds were designed, synthesized, and fully characterized. Photophysical and electrochemical properties of these compounds were investigated. Organic-inorganic hybrids retained the unique photophysical properties of their precursor pyrene compounds. Additionally, functionalization of inorganic POM moiety with organic bis-pyrene compound influenced the redox properties of the Mn-Anderson core.

ROS scavenging of SOD/CAT mimics probed by EPR and reduction of lipid peroxidation in S. cerevisiae and mouse liver, under severe hydroxyl radical stress condition

The interaction between CuII, FeIII and MnII complexes, derived from the ligands 1-[bis(pyridine-2-ylmethyl)amino]-3-chloropropan-2-ol (hpclnol) and bis(pyridine-2-ylmethyl)amine (bpma), and the free radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) and reactive oxygen species (ROS), was investigated by colorimetric and EPR (Electron Paramagnetic Resonance) techniques. A comparison between these results and those reported to [Mn(salen)Cl] or EUK-8 was also addressed. EPR studies allowed us the identification of intermediates species such as superoxide‑copper(I) and superoxide‑copper(II), a mixed-valence FeIIIFeII species and a 16-line feature attributed to MnIII-oxo-MnIV species. The biomarker malondialdehyde (MDA) was determined by TBARS assay in S. cerevisiae cells, and the determination of the IC50 indicate that the antioxidant activity shown dependence on the metal center (CuII ≈ FeIII > MnII ≈ [Mn(salen)Cl]. The lipid peroxidation attenuation was also investigated in liver homogenates obtained from Swiss mice and the IC50 values were in the nanomolar concentrations. We demonstrated here that all the complexes interact with the free radical DPPH and with ROS (H2O2, O2•- and hydroxyl radical), enhancing the cellular protection against oxidative stress generated by hydroxyl radical, employing two experimental model systems, S. cerevisiae (in vivo) and mouse liver (ex vivo).

Ligands-triggered evolution of catalytic intermediates during periodate activation via soluble Mn(II) for organic contaminants’ abatement

Homogenous catalysis technology could be flexibly combined with existing water treatment facilities, which presents broad applicational prospects and deserves systematic study. This work reinvestigated the periodate (IO4−, PI) activation process mediated by hydrated MnII ions and highlighted the critical involvement of the in-situ formed colloidal MnO2 (MnIV). MnII ions were directly oxidized to colloidal MnIV in the MnII/PI system, and the nascent MnIV could in turn activate PI to form MnIV-PI* complex as the reactive oxidant. Besides, several kinds of ligands were introduced into the MnII/PI oxidation system to explore their influences. Nitrilotriacetic acid (NTA) outperformed other selected ligands and could significantly enhance PI activation to degrade organic contaminants, which could achieve a removal efficiency of ∼99% within seconds. Interestingly, the presence of NTA completely altered the catalytic pathways rather than just accelerating the generation of reactive oxidants. Combining the results of sulfoxide-probe transformation tests and the 18O isotope-tracer experiments, we proposed that the high-valent manganese-oxo (MnV-oxo) species was the dominant reactive oxidant generated in the MnII/NTA/PI system, and the metastable MnIII complex was the precursor of the MnV-oxo species. Notably, maintaining the MnII high-spin d5 center and stabilizing the in-situ formed MnIII intermediates were the crucial premises for the evolution of the catalytic oxidation process triggered by functional ligands. This work clarified the critical involvement of functional ligands during PI activation via soluble MnII and might also inspire the designing of heterogeneous catalyst modification for the water treatment technology.

MnII, ZnII and CdII Dinuclear Complexes Based on Mixed Benzoic Acid and Metronidazole Benzoate: Syntheses, Crystal structures, Spectroscopic, Hirshfeld surface analysis, and Molecular modelling of their potential activity against Porphyromas gingivalis

Three novel complexes, [Mn(μ-Bz)2(METB)]2, (1); [Zn(μ-Bz)2(METB)]2, (2); and [Cd(μ-Bz)2(METB)]2 (3), where Bz = Benzoate and METB = Metronidazole Benzoate were prepared and characterized. Crystals of these complexes are prepared at room temperature by combining various metal(II) salts with benzoic acid and metronidazole benzoate in an ethanolic and NaOH solution. Single crystal X-ray crystallography, PXRD, and spectroscopic techniques (FTIR, Raman, UV–Vis) have been used to confirm the structure of the newly synthesized complexes. In their crystallographic examinations, all compounds are found to be paddle-wheel or dinuclear in nature and crystallized in a triclinic crystal system with a space group of P-1. In the analyzed structures 1–3, we observe various modes of binding bridging benzoate ligands to metal center. The Hirshfeld surface area calculations were used to further analyze more in-depth of the weak non-covalent interactions exhibited in the crystal lattices of the complexes. In addition, computational molecular docking simulations were utilized to evaluate the potential anti-periodontitis activity of the compounds against two (2) Porphyromas gingivalis proteins: 1CVR and 6I9A. In 1CVR protein, docking of Bz (-36 kJmol−1), METB (-40.16 kJmol−1) and 1, -42.41; 2, -43.71; 3, -40.12 kJmol−1 were examined where 2 showed the highest binding propensity, strength, stability, and negative scoring function. Also, in all docked complexes with 6I9A, 2 revealed highest scoring function and binding affinity based to its most negative binding free energy value, ∆G (-35.64 kJmol−1) than 1 (-25.81), 3 (-28.81) and their ligands (Bz = -19.93; METB = -25.06 kJmol−1 respectively). In addition to interacting with DNA, the complexes exhibited nontoxicity.

Antiferromagnetically coupled iso-structural CrIII, MnIII and FeIII complexes of a tetradentate Schiff base ligand derived from o-phenylenediamine

Antiferromagnetically coupled iso-structural CrIII, MnIII and FeIII complexes of a tetradentate Schiff base ligand derived from o-phenylenediamine

Deciphering the Metal Speciation in Low‐Molecular‐Weight Complexes by IMS‐MS: Application to the Detection of Manganese Superoxide Dismutase Mimics in Cell Lysates

AbstractThe detection and quantification of exogenous metal complexes are crucial to understanding their activity in intricate biological media. MnII complexes are difficult to detect and quantify because of low association constants, and high lability. The superoxide dismutase (SOD) mimic (or mimetic) labelled Mn1 is based on a 1,2‐di‐aminoethane functionalized with imidazole and phenolate and has good intrinsic anti‐superoxide, antioxidant and anti‐inflammatory activities in lipopolysaccharide (LPS)‐activated intestinal epithelial HT29‐MD2 cells, similar to that of its propylated analogue labelled Mn1P. Ion mobility spectrometry‐mass spectrometry (IMS‐MS) is a powerful technique for separating low molecular weight (LMW) metal complexes and can even separate complexes with the same ligand but bound to different divalent metal cations with similar ionic radii. We demonstrated the intracellular presence of the Mn1 and Mn1P complexes, at least partly intact, in lysates of cells incubated with the complexes and estimated the intracellular Mn1P concentration using a Co‐13C6 analogue.

Deciphering the Metal Speciation in Low‐Molecular‐Weight Complexes by IMS‐MS: Application to the Detection of Manganese Superoxide Dismutase Mimics in Cell Lysates

The detection and quantification of exogenous metal complexes are crucial to understanding their activity in intricate biological media. MnII complexes are difficult to detect and quantify because of low association constants, and high lability. The superoxide dismutase (SOD) mimic (or mimetic) labelled Mn1 is based on a 1,2-di-aminoethane functionalized with imidazole and phenolate and has good intrinsic anti-superoxide, antioxidant and anti-inflammatory activities in lipopolysaccharide (LPS)-activated intestinal epithelial HT29-MD2 cells, similar to that of its propylated analogue labelled Mn1P. Ion mobility spectrometry-mass spectrometry (IMS-MS) is a powerful technique for separating low molecular weight (LMW) metal complexes and can even separate complexes with the same ligand but bound to different divalent metal cations with similar ionic radii. We demonstrated the intracellular presence of the Mn1 and Mn1P complexes, at least partly intact, in lysates of cells incubated with the complexes and estimated the intracellular Mn1P concentration using a Co-13 C6 analogue.

Ct-DNA binding and antimicrobial studies of MnII and FeII macrocyclic complexes

Ct-DNA binding and antimicrobial studies of MnII and FeII macrocyclic complexes