Row Transition Metal Ions Research Articles

Biocompatibility of ionic liquid tagged terpyridine complexes with potent biological activity

The current work deals with the study of novel and bioactive ionic liquid tagged terpyridine ligand and their complexes were synthesized using first row transition metal ions. The synthesized IL tagged complexes were characterized by UV, FT-IR, 1H NMR, 13C NMR, HRMS spectroscopic studies and also the structure of the complexes was confirmed by its spectral data. Moreover, the antibacterial, antifungal, antioxidant and anticancer studies were carried out to exhibit the bioactivity of the complexes. The antimicrobial studies of newly synthesized complexes were tested against five bacterial and two fungal strains by disc diffusion method. The iron complexes of terpyridine shows outstanding activity than the reference with zone of inhibition of 22-32 mm against the evaluated microorganisms. Furthermore, the antioxidant activity of the terpyridine complexes was assessed by phosphomolybdenum and NO radical scavenging assay. The reducing power of the synthesized complexes has shown potent antioxidant activity than the standard. Especially, Cu-tpy-IL and Zn-ttpy-IL have shown good radical scavenging activity exhibits an IC50 value of 42.45 and 40.85 µg/mL respectively. In addition, the anticancer activity of the complexes was analyzed by SRB assay. The report suggested that the complexes of Cu-ttpy-IL and Zn-ttpy-IL exhibiting prominent role in anticancer activity against HeLa and HT-29 cell lines possessing a GI50 value of <10 µg/mL. The obtained results revealed that the bioactive synthesized complexes could be used as a derivative in the field of drug inventions.

Hydroxybenzoate salts of cobalt(II), manganese(II), and nickel(II): synthesis, crystal structure, Hirshfeld surface analyses, and thermal behavior

The reaction of hydroxybenzoates with divalent first row transition metal ions afforded four mononuclear complexes, [M(OH2)6](dhbzc)2·2H2O (M = Co2+, 1 or Mn2+, 2), [Ni(OH2)6](hbzc)2·2H2O (3) and [Ni(OH2)5(hbzc)](hbzc)·3H2O (4) (where dhbzc− = 2,6-dihydroxybenzoate and hbzc− = 4-hydroxybenzoate). The complexes were characterized by single crystal and powder X-ray diffraction analyses, infrared spectroscopy, and thermogravimetric analysis. Results showed that the hydrogen bonds present in dhbzc− impaired its coordination to Co2+ and Mn2+. Thereafter, Hirshfeld surface analyses (HS) and 2D fingerprint plots were used to investigate the intermolecular contacts in 1–4. The offset π···π stacking of the dhbzc− counterions in 1 and 2 lead to C···C close contacts over C···H/H···C ones. Complexes 3 and 4 presented the usual herringbone aromatic-based packing for the hbzc− rings with a predominance of C···H/H···C close contacts. The existence of water molecules in the crystal lattices of 1–4 was determined by TG analyses, which proved the presence of coordinated and uncoordinated water molecules. The thermal decomposition patterns were analyzed in light of the percentage of the strongest intermolecular close contacts.

Structure and magnetism across the Sr2−xBaxNiOsO6 phase diagram: Understanding magnetic superexchange between first and third row transition metal ions

The crystal chemistry and magnetism of compositions in the Sr2−xBaxNiOsO6 phase diagram have been investigated to better understand the superexchange interactions between 3d and 5d transition metal ions. Compositions with x ​< ​1.35 crystallize with the double perovskite structure, while those with x ​> ​1.83 crystallize in a trigonal structure that is a cation ordered variant of the 6H hexagonal perovskite structure. The Sr-rich double perovskites undergo a cubic to tetragonal distortion upon cooling that is driven by out-of-phase octahedral tilting. The tetragonal distortion occurs upon cooling below 650 ​K in Sr2NiOsO6. The temperature of this transition decreases as the barium content increases and is completely suppressed for x ​≥ ​1.2. All compositions in the double perovskite region become spin glasses below Tg ​≈ ​40 ​K, due to the competition between ferromagnetic Ni–Os and antiferromagnetic Ni–Ni and Os–Os superexchange interactions. The double perovskite compositions that are rich in barium, like Sr0.8Ba1.2NiOsO6 show some signs of magnetic ordering in small clusters, but the presence of Ba/Sr disorder inhibits long-range magnetic order. Trigonal Ba2NiOsO6 orders ferrimagnetically below TC ​= ​108 ​K. The magnetic structure of this compound contains ferromagnetic ∼180° Ni–O–Os interactions and antiferromagnetic ∼90° Ni–O–Os interactions, both in agreement with the Goodenough-Kanamori rules.

MII (M = Mn, Fe, Co, Ni and Cu) complexes with a chromone-derived neutral ligand: synthesis, structural characterization, photocatalytic and mycobacterial activity studies

This work provides the coordination chemistry of the resulting compound of 2-(2-furyl)-3-hydroxychromone and nicotinoyl chloride with first row transition metal ions. Good performance in H2 evolution was shown by the copper-containing photocatalyst.

Potentiometric determination of stability constants of ternary complexes of first row transition metal ions with ditopic azelaic acid dihydrazide and aspartic acid in aqueous medium

A Chemical speciation study of ternary complexes containing transition metal ions (Mn2+,Co2+,Ni2+, Cu2+ and Zn2+) with a ditopic novel ligand L ​= ​Azelaic acid dihydrazide (AZDH) and X ​= ​l-Aspartic acid of type [MmLlX xHh], (where m ​= ​1, 2; l ​= ​1; x ​= ​1, 2 and h ​= ​−2 to 5) in different ratios of M:L:X ​= ​1:1:1, 1:2:1, 2:1:1and 2:1:2 was carried out using pH -potentiometric method of data acquisition and applied to chemometric modelling methods of analysis. MINIQUAD-75 program was used for the resolution of the plausible species and their corresponding formation constants at 303 ​± ​0.1 ​K, and 0.01 ​M ionic strength. Species concentration distribution diagrams were generated using HySS program. Best-fit chemical models were selected on the basis of statistical parameters like Standard deviation (SD), U (sum of the squares of the residuals in mass balance equations), and chi-square test etc. Relatively stable ternary complexes were evaluated quantitatively using Δlog K formulation. All the formation constants for the species were compared for Irving-Williams order of stability.

Synthesis, Characterization, Antimicrobial and Antioxidant Studies of Co(II), Ni(II), Cu(II) and Zn(II) Metal Complexes with the Ligands 2-{[4-(5-bromo thiophen-2- yl)-6- phenylpyrimidin-2 yl]carbonoimidoyl}phenol Derivatives

A few complexes 2-{[4-(5-bromo thiophen-2-yl)-6-phenyl pyrimidin-2-yl] carbonoimidoyl} phenol [HL5] and 2-{[4-(5-bromo thiophen-2-yl) -6- phenyl pyrimidin-2-yl]carbon imidoyl}-5-methoxyphenol [HL6] with first row transition metal ions have been reported in this paper. The stichiometry of type (1:1) [M(L)]2H2O is analysed by these complexes. Complexes with ligands (HL5 and HL6) of metal ions Co(II), Ni(II), Cu(II) and Zn(II) reveal co- ordination number six, by means of magnetic susceptibility, electronic, IR, 1H NMR, X-ray diffraction and ESR spectrum data. Copper(II) complexes with (HL5) and (HL6) were studied spectrophotometrically at different temperatures having an absorption maxima of 535 nm. The findings demonstrate that copper(II) and (HL5) and (HL6) are combined at pH 5.0 at a molar ratio of 1:1. The stability constants of the complexes were calculated to be 13.06×104, 14.51×104 and 10.40×104 and 13.18x104, 15.06x104, 11.23x104 for (HL5) and (HL6) respectively by Jobs continuous variation method and 0.24×104, 0.57×104, and 0.77×104 and 0.28×104, 0.55×104, 0.79×104 for (HL5) and (HL6) respectively by mole ratio method at 30, 35 and 40°C, respectively. Both ligands and their metal complexes were screened for their antibacterial and antifungal activity by cup plate method and antioxidant activity by using standard DPPH radical scavenging ability method.

Rational design of novel carboxylic acid functionalized phosphonium based ionic liquids as high-performance extractants for rare earths

Developing the novel ionic liquids as the potential substitutes for conventional organic solvents in extraction of the rare-earth metals is highly desirable but challenges still remain. In this study, the well-designed carboxylic acid functionalized phosphonium based ionic liquids, (4-carboxyl)butyl-trioctyl-phosphonium chloride/nitrate, were synthesized and characterized. The as-prepared samples were tested as the undiluted hydrophobic acidic extractant for rare-earth metal ions, affording the maximal loading of 3 mol/mol towards Nd(III) in aqueous solution and the remarkable stripping performance. The results also reveal their excellent extractability and selectivity for Sc(III) in the mixtures of six rare-earth ions, as well as the outstanding separation properties between rare-earth and first row transition-metal ions (i.e., La/Ni, Sm/Co). Moreover, the extraction mechanism indicates that the extracted rare-earth complex via a proton exchange in the ionic liquid phase is structurally similar to the complexes obtained with neutral extractants. This work presents a prototype for the fabrication of the hydrophobic cation-functionalized ionic liquids for highly efficient rare-earth extraction and provides the future application in recycling of rare-earth metals from the spent magnets.

Anthracene conjugated carboxylic acids for luminescent materials: Design, synthesis and photophysical studies

Two new carboxylic acids conjugated with anthracene (1 and 2) are synthesized with a target to explore their coordination chemistry with metal ions. Compounds 1 and 2 are completely characterized by various analytical (NMR, Elemental analysis and ESI-Mass) methods. The backbone (biphenyl and phenyl) of compounds1 and 2 differs in such a way that the electronic communication between carboxylic acid and anthracene moieties can be easily modified. Compound 2 show anthracene centred emission while 1 exhibit combination of charge transfer transition and anthracene centred emissions. Preliminary fluorescence studies reveal compound 1 and 2 show different fluorescence response for first row transition metal ions.

Magnetic and Photoluminescent Sensors Based on Metal-Organic Frameworks Built up from 2-aminoisonicotinate

In this work, three isostructural metal-organic frameworks based on first row transition metal ions and 2-aminoisonicotinate (2ain) ligands, namely, {[M(μ-2ain)2]·DMF}n [MII = Co (1), Ni (2), Zn (3)], are evaluated for their sensing capacity of various solvents and metal ions by monitoring the modulation of their magnetic and photoluminescence properties. The crystal structure consists of an open diamond-like topological 3D framework that leaves huge voids, which allows crystallizing two-fold interpenetrated architecture that still retains large porosity. Magnetic measurements performed on 1 reveal the occurrence of field-induced spin-glass behaviour characterized by a frequency-independent relaxation. Solvent-exchange experiments lead successfully to the replacement of lattice molecules by DMSO and MeOH, which, on its part, show dominating SIM behaviour with low blocking temperatures but substantially high energy barriers for the reversal of the magnetization. Photoluminescence studied at variable temperature on compound 3 show its capacity to provide bright blue emission under UV excitation, which proceeds through a ligand-centred charge transfer mechanism as confirmed by time-dependent DFT calculations. Turn-off and/or shift of the emission is observed for suspensions of 3 in different solvents and aqueous solutions containing metal ions.

Studies on the Complexation of 3d Transition Metal Ions with NR/PEO Block Copolymer in Aqueous Medium

Polyethylene oxide (PEO) was chemically linked to natural rubber (NR) segments to form a block copolymer (BC), which proved to be a suitable material for complexing with selected first row transition metal ions in aqueous solution through batch adsorption method under noncompetitive mode. Optimum conditions for sorption were found to be 20 mmol/L initial concentration, pH at 6, ambient temperature, and 24 h. The order of decreasing adsorption capacity obtained is Mn(II) &gt; Co(II) &gt; Zn(II) &gt; Ni(II) &gt; Cu(II) &gt; Fe(III). Freundlich isotherm shows the best fit indicating that the adsorption is of heterogeneous in nature. The complexation follows pseudo second‐order kinetics. Exothermic character of the complexation was confirmed by thermodynamic study. For all metal ions, the standard free energy change values are negative for the different temperatures studied, which confirms the spontaneous character of the process. At ambient temperature, the free energy change lies between −2.35 and − 7.83 kJ/mol for all complexes. Values of activation energy for all the metal ion complexation is within the range 11–25 kJ/mol, which indicates chemical interaction via activated physico–chemical adsorption. Variation in stability constant of the complexes also follows the same order as given above. POLYM. ENG. SCI., 60:661–672, 2020. © 2020 Society of Plastics Engineers

Engineering band edge properties of WO3 with respect to photoelectrochemical water splitting potentials via a generalized doping protocol of first-row transition metal ions

The photoelectrochemical (PEC) water splitting efficiency of WO3 is limited because to its wide band gap, which allows limited absorption of incident sunlight and its unsuitable band edge positions with respect to overall water splitting potentials. Therefore, band edge engineering of WO3 is essential for reducing the band gap and altering band edge positions via substitutional doping of metal ions. Hence, we report a facile and generalized protocol for synthesizing first row transition metal ion (V, Cr, Mn, Fe, Co, Ni, Cu and Zn,) -doped WO3 thin films and explore their band-edge and PEC water-splitting properties. The detailed characterization results show that irrespective of the type of dopant, the morphology is found to change upon doping, whereas the crystal phase, crystal facet, band gap, charge-transfer resistance, carrier density, and oxygen vacancy formation depend on the type of dopant. The band-edge positions of doped WO3 are plotted with respect to a reference hydrogen electrode, revealing a reduction and widening of the band gap and an upward and downward shift in conduction and valence band-edge positions induced by dopants. Overall, our results provide valuable insights into fabricating highly engineered WO3 photoanodes for efficient future PEC water-splitting capabilities.

Evaluation of nonlinear optical properties from molecular descriptors of benzimidazole metal complexes by principal component analysis

In the present work, semiempirical quantum chemical method (PM6) has been used for the simulation of molecular descriptors of first row transition metal ions incorporated benzimidazole metal complexes. Metal complexes with and without substituents are considered for the analysis. In both the cases, molecules show distinct properties with respect to the molecular descriptors. Since the dimension of the data set is large, principal component analysis has been used and the obtained principal components, PCA1 and PCA2, are linearly regressed with hyperpolarizability values. The obtained results indicate that molecular energy plays a dominant role in the nonlinear optical properties of benzimidazole metal complexes. Further, it is observed that the bond angle, global hardness and heat of formation of the molecules have considerable impact on the hyperpolarizability values.

Facile one pot synthesis of tetraamide macrocyclic complexes using malonyldihydrazide and p-nitrobenzaldehyde at room temperature

Facile one pot synthesis of a series of seven tetraamide macrocyclic complexes of first row transition metal ions such as Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) is carried out using malonyldihydrazide and p-nitrobenzaldehyde at room temperature using template method. The characterization and structure determination of synthesized complexes was carried out using various analytical techniques such as melting point determination, IR, UV/Visible, 1H NMR, Mass spectra, magnetic susceptibility and molar conductance measurements. The results obtained indicated towards the presence of an octahedral geometry of the complexes. The synthesized complexes were screened for their antibacterial activities.

Weak and Reversible Binding of Alkali Metal Ions (Na+/K+) by an Aza‐Oxa Cryptand

AbstractA laterally asymmetric cryptand incorporating amino N and ethereal O was utilized to bind the hard alkali metal ions (Na+ and K+) in aqueous medium. Single crystal X‐ray diffraction studies revealed that both Na+ and K+ ions were included inside the cryptand cavity. However, the trapped metal ions were weakly bound and could be released from the cavity of the cryptand. This cryptand had been used as a column chromatographic material for trapping Na+ and K+ ions from water as the trapped metal ion could be released back into water to extract the cryptand in its free state. Metal binding capability of the cryptand was evaluated using computational studies that revealed lower binding energy (B.E.) for the Na+ and K+ ions compared to first row transition metal ions.

Four-coordinated see-saw N-(aryl)-2-(propan-2-ylidene)hydrazinecarbothioamide complexes of nickel(ii), copper(ii) and zinc(ii) and their propensity for catalytic cyclisation.

A series of mononuclear complexes of divalent nickel and zinc with N-(4-methoxyphenyl)-2-(propan-2-ylidene)hydrazine carbothioamide (H2Lmethoxy) as well as with N-(4-nitrophenyl)-2-(propan-2-ylidene)hydrazine carbothioamide (H2Lnitro) have been structurally characterised. Among these two ligands, H2Lnitro formed an analogous copper(ii) complex to that of nickel and zinc, whereas H2Lmethoxy undergoes a catalytic cyclisation reaction in the presence of copper(ii) nitrate trihydrate. Control experiments based on ESR have revealed that copper(ii) is reduced to copper(i) and reverts back to copper(ii) as the cyclisation reaction proceeds, generating a catalytic reaction. The crystal structures of H2Lnitro and H2Lmethoxy show that the plane of the phenyl ring with respect to the plane of the hydrazine-containing unit in H2Lnitro is more or less coplanar, whereas the H2Lmethoxy molecule is non-planar with a 67.05° angle between these planes. DFT calculations have shown a large difference in the localisation of electrons in the HOMO of the two ligands; the HOMO of H2Lmethoxy is spread over the aromatic ring, which facilitates involvement of the ring in the formation of a C-N bond through a single electron transfer to a copper(ii) ion. This cyclic product has a distinguishable absorption maximum at 299 nm, which makes it possible to detect copper ions over other first row transition metal ions and alkali metal ions. On the other hand, the copper(ii) complex of H2Lnitro shows a characteristic absorption at 395 nm in the presence of fluoride ions, whereas the free ligand with fluoride shows absorption at 418 nm, which shows that the interactions of the ligand with fluoride and with the corresponding copper complex widely differ.

Mononuclear late first row transition metal complexes of ONO donor hydrazone ligand: Synthesis, characterization, crystallographic insight, in vivo and in vitro anti-inflammatory activity

Air and moisture stable coordination compounds of late first row transition metal ions, viz., Co(II), Ni(II), Cu(II) and Zn(II) with a newly designed ligand, (E)-2-amino-N'-(1-(2-hydroxy-6-methyl-4-oxo-4H-pyran-3-yl)ethylidene)benzohydrazide (H2L) were prepared and extensively characterized using various spectro-analytical techniques. The ligand acts both in mono as well as doubly deprotonated manner. The ligand to metal stoichiometry was found to be 1:2 in case of complexes using chloride salts, whereas 1:1 in case of copper (II) complex using its acetate salt. The molecular structures of H2L, nickel and copper complexes were unambiguously determined by single-crystal X-ray diffraction studies reveal that H2L exists in a zwitterionic form while copper complex has copper centre in a distorted square planar environment. On the other hand, cobalt, nickel and zinc complexes display distorted octahedral coordination around the metal ion. In case of [Ni(HL)2].H2O, intramolecular CH⋯π stacking interaction were observed between the centroid of five membered chelate ring and phenyl proton C5H5 and intermolecular CH⋯π stacking interaction between the centroid of phenyl ring, dehydroacetic acid (DHA) ring and phenyl protons. The [Cu(L)DMF] complex is stabilized by intramolecular hydrogen bonding N1H⋯N2 and by intermolecular hydrogen bonding N1H⋯O4. Intermolecular interactions were investigated by Hirshfeld surfaces. Further, H2L and its metal complexes were screened for their in vivo and in vitro anti-inflammatory activities. The activity of the ligand has enhanced on coordination with transition metals. The tested compounds have shown excellent activity, which is almost equipotent to the standard used in the study.

Reducing Power of Phosphate Matrix in Binary Barium Phosphate Glasses Doped with 3d Transition Metals and Effects of Gamma Radiation

Spectroscopic characterization was performed for base and first row transition metal ions (3d TM) doped barium metaphosphate glasses. The procedure was conducted using FTIR and optical spectral measurements before and after 8 M rad gamma irradiation. Electronic spectra show distinct UV absorption with a peak around 230 nm in nearly all samples correlated with trace iron ions present as an impurity within the chemicals used for the preparation of the glasses. 3d TM ions-doped samples exhibit additional characteristic bands mainly in the visible due to each respective TM ion. Such optical spectra indicate and support the assumption that the host phosphate glass generally promotes the reduced state or octahedral coordination of the TM ions to a measurable extent. Gamma irradiation produces mostly an extension of the UV spectra and this effect is correlated with the assumption of photochemical reactions of the trace iron ions impurities during the irradiation process in which some ferrous ions capture positive holes and are transformed to additional ferric ions causing the extension. FTIR absorption spectra reveal vibrational bands due mainly to metaphosphate groups and the P-O-P mode while TM ions doped glasses show no distinct variations due to the stability of the phosphate network containing high content of heavy Ba2+ ions and the presence of TM ions in low doping percent.

Synthesis, Spectral Studies and Antimicrobial Activity of Mixed Ligand Complexes of Cephalexin and Dimethylglyoxime with Some First Row Transition Metal Ions

In this paper,six new mixed metal ligand complexes are reported with Cephalexin (Ceph.H) as a primary ligand and Dimethylglyoxime (DMG) as secondary ligand with metal Chloride [MCl2 .nH2O. = Mn(II), Co(II),Cu(II), Ni(II) and Zn(II), n=0-6], CrCl3.6H2O. The complexes are of (1:1:1)(Metal:Ligand: Ligand) Stoichiometry. The structures of these complexes are confirmed by using FT-IR and UV-electronic spectroscopies, magnetic moments, melting points, molar conductivity measurements and the metal % analysis revealed that the complexes analyze indicates a four coordinated as (A)=[M(HDMG) (Ceph)]. M=[Ni(II)and Zn(II). Six coordinated as (B) = K2[M(DMG)(CePh)(H2O)]. M= Mn (II),Co(II) and Cu(II) and (C)=[Cr(DMG)(Ceph)]Cl2. Interestingly, the in-vitro antimicrobial studies on (CephH) and dimethylglyoxime) ligands and mixed metal ligand complexes against {(Staphylococcus aureus, Bacillus Subtilis, and Enterobacter Cloacae)} by measuring the zone of inhibition in mm. Electronic spectra data and magnetic measurements indicates that the most of the complexes have octahedral geometry except the complexes Ni (II) and Zn (II) have tetrahedral geometry.

Metal-selective coordination and enhanced fluorescence of a self-assembling ligand scaffold

A fluorescent hydroxyiminonicotinonitile (HINT) coordinating group can be incorporated into self-assembling ligand scaffolds, and shows metal-selective assembly and enhanced fluorescence. The assembly process is dependent on ligand coordination angle, and coordination only occurs for oxophilic first row transition metal ions, with affinity enhanced by the supramolecular assembly process. The ligands are weakly emissive, and show strong enhancement in fluorescence upon Zn2+ coordination, whereas Co2+ or Fe2+ cause complete quenching.

Zinc stress induces copper depletion in Acinetobacter baumannii

BackgroundThe first row transition metal ions zinc and copper are essential to the survival of many organisms, although in excess these ions are associated with significant toxicity. Here, we examined the impact of zinc and copper stress on Acinetobacter baumannii, a common opportunistic pathogen.ResultsWe show that extracellular zinc stress induces a copper-specific depletion phenotype in A. baumannii ATCC 17978. Supplementation with copper not only fails to rescue this phenotype, but further exacerbates the copper depletion. Extensive analysis of the A. baumannii ATCC 17978 genome identified 13 putative zinc/copper resistance efflux pumps. Transcriptional analyses show that four of these transporters are responsive to zinc stress, five to copper stress and seven to the combination of zinc and copper stress, thereby revealing a likely foundation for the zinc-induced copper starvation in A. baumannii. In addition, we show that zinc and copper play crucial roles in management of oxidative stress and the membrane composition of A. baumannii. Further, we reveal that zinc and copper play distinct roles in macrophage-mediated killing of this pathogen.ConclusionsCollectively, this study supports the targeting of metal ion homeostatic mechanisms as an effective antimicrobial strategy against multi-drug resistant bacterial pathogens.