Bivalent Transition Metal Ions Research Articles

Stability constants of ternary complexes β-lactam antibiotic drugs with bivalent transition metal(II) ions in the presence of aliphatic amino acids

Stability constants of ternary complexes β-lactam antibiotic drugs with bivalent transition metal(II) ions in the presence of aliphatic amino acids

Biomass derived green carbon dots for sensing applications of effective detection of metallic contaminants in the environment

The rapid consumption of metals and unorganized disposal have led to unprecedented increases in heavy metal ion concentrations in the ecosystem, which disrupts environmental homeostasis and results in agricultural biodiversity loss. Mitigation and remediation plans for heavy metal pollution are largely dependent on the discovery of cost-effective, biocompatible, specific, and robust detectors because conventional methods involve sophisticated electronics and sample preparation procedures. Carbon dots (CDs) have gained significant importance in sensing applications related to environmental sustainability. Fluorescence sensor applications have been enhanced by their distinctive spectral properties and the potential for developing efficient photonic devices. With the recent development of biomass-functionalized carbon dots, a wide spectrum of multivalent and bivalent transition metal ions responsible for water quality degradation can be detected with high efficiency and minimal toxicity. This review explores the various methods of manufacturing carbon dots and the biochemical mechanisms involved in metal detection using green carbon dots for sensing applications involving Cu (II), Fe (III), Hg (II), and Cr (VI) ions in aqueous systems. A detailed discussion of practical challenges and future recommendations is presented to identify feasible design routes.

Magnetic and Electronic Properties of Highly Mn-Doped β-NaGdF4 and β-NaEuF4 Nanoparticles with a Narrow Size Distribution

We have performed a detailed study of the magnetic and electronic properties of highly manganese-doped β-NaGdF4 and β-NaEuF4 nanoparticles with a narrow size distribution. XPS as well as XRF experiments confirm the successful doping of 11 ± 2% Mn into β-NaGdF4 and β-NaEuF4 nanoparticles, i.e., a much higher Mn concentration than has been previously reported for the incorporation of bivalent transition metal ions into the β phase of NaREF4 (RE = rare earth) nanocrystals. Owing to the high manganese concentration, we observed quenching of the Mn2+ emission in both materials and even quenching of the red Eu3+ emission in β-NaEuF4:11% Mn particles. We have investigated the Mn–Mn magnetic interactions by means of EPR spectroscopy, and SQUID magnetometry further supports a significant increase of the magnetization of the Mn-doped β-NaEuF4 nanoparticles compared to pure β-NaEuF4. By using element specific X-ray absorption spectroscopy and X-ray magnetic circular dichroism, we show that the magnetism of Mn-doped β-NaEuF4 is dominated by the divalent Mn ions for Mn-doped β-NaEuF4. A parallel alignment of the gadolinium and manganese magnetic moments is found.

Metal-Ion Batteries Based on New Copper and Nickel Coordination Polymers with Aromatic Polyamine Ligands

Redox-active materials with high electron and ion conductivities are required for the new generation of metal-ion batteries (MIBs) with high energy density and high rate capability. Recently, a novel family of conductive (>1 S/cm) and electrochemically active metal organic frameworks (MOFs) composed of aryl amine ligands and bivalent transition metal ions (Cu2+, Ni2+, Co2+) has been reported. However, this class of MOFs remains virtually unexplored in metal-ion batteries. In particular, the only structures tested in MIBs are based on hexaaminobenzene, a molecule that readily decomposes or gets oxidized during synthesis or while handling, which limits its applicability. Here we report new Ni(II) and Cu(II) coordination polymers derived from commercially available or easily synthesizable polyamines, e.g. 1,2,4,5-tetraaminobenzene tetrahydrochloride (TAB*4HCl), etc. A series of target MOFs was synthesized by simply mixing the ligand and the transition metal salt in the presence of air and ammonia. The novel materials are characterized using a set of complementary techniques including solid-state NMR, elemental analysis, IR spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and electron microscopy. Their electrochemical behavior is rationalized using impedance spectroscopy monitoring and ex situ XPS. The obtained MOFs were successfully applied as both cathode and anode materials in lithium- and sodium-ion batteries and demonstrated ultra-high rate capability and stability. For example, a specific capacity of 83 mAh/g can be reached for the Ni(II) polymer derived from TAB*4HCl at 20 A/g current rate (>250 C) in 0.8-2.0 V vs. Li/Li+ range, while 79% of this capacity is retained after 20000 cycles. Another example is the Cu-TAB coordination polymer, which shows a specific capacity up to 262 mAh/g in 1.5-4.1 V vs. Li/Li+ range, which corresponds to the energy density of 616 Wh/kg. The revealed correlations between the molecular structures of MOFs, their physicochemical properties and electrochemical performance pave a way to rational design of new coordination polymers for advanced metal-ion batteries.

Structure and Dynamics of Alginate Gels Cross-Linked by Polyvalent Ions Probed via Solid State NMR Spectroscopy.

Alginate gels are an outstanding biomaterial widely applicable in tissue engineering, medicine, and pharmacy for cell transplantation, wound healing and efficient bioactive agent delivery, respectively. This contribution provides new and comprehensive insight into the atomic-resolution structure and dynamics of polyvalent ion-cross-linked alginate gels in microbead formulations. By applying various advanced solid-state NMR (ssNMR) spectroscopy techniques, we verified the homogeneous distribution of the cross-linking ions in the alginate gels and the high degree of ion exchange. We also established that the two-component character of the alginate gels arises from the concentration fluctuations of residual water molecules that are preferentially localized along polymer chains containing abundant mannuronic acid (M) residues. These hydrated M-rich blocks tend to self-aggregate into subnanometer domains. The resulting coexistence of two types of alginate chains differing in segmental dynamics was revealed by 1H-13C dipolar profile analysis, which indicated that the average fluctuation angles of the stiff and mobile alginate segments were about 5-9° or 30°, respectively. Next, the 13C CP/MAS NMR spectra indicated that the alginate polymer microstructure was strongly dependent on the type of cross-linking ion. The polymer chain regularity was determined to systematically decrease as the cross-linking ion radius decreased. Consistent with the 1H-1H correlation spectra, regular structures were found for the gels cross-linked by relatively large alkaline earth cations (Ba2+, Sr2+, or Ca2+), whereas the alginate chains cross-linked by bivalent transition metal ions (Zn2+) and trivalent metal cations (Al3+) exhibited significant irregularities. Notably, however, the observed disordering of the alginate chains was exclusively attributed to the M residues, whereas the structurally well-defined gels all contained guluronic acid (G) residues. Therefore, a key role of the units in M-rich blocks as mediators promoting the self-assembly of alginate chains was experimentally confirmed. Finally, combining 2D 27Al 3Q/MAS NMR spectroscopy with density functional theory (DFT) calculations provided previously unreported insight into the structure of the Al3+ cross-linking centers. Notably, even with a low residual amount of water, these cross-linking units adopt exclusively 6-fold octahedral coordination and exhibit significant motion, which considerably reduces quadrupolar coupling constants. Thus, the experimental strategy presented in this study provides a new perspective on cross-linked alginate structure and dynamics for which high-quality diffraction data at the atomic resolution level are inherently unavailable.

Thermal behavior of glycolic acid, sodium glycolate and its compounds with some bivalent transition metal ions in the solid state

Synthesis, characterization and thermal behavior of some transition metal glycolates, M(C2H3O3)2 [M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)], as well as the thermal behavior of glycolic acid and its sodium salt (NaC2H3O3) were investigated employing simultaneous thermogravimetry and differential thermal analysis, infrared spectroscopy (FTIR), simultaneous thermogravimetry–differential scanning calorimetry coupled to FTIR (evolved gas analysis), complexometry and high-resolution electrospray ionization mass spectrometry. The lowest energy model structure of each complex has been proposed by using the density functional theory at the B3LYP/6-311++g(d) level of theory. The results provided information concerning the composition, dehydration, thermal stability, thermal decomposition and identification of the gaseous products evolved during the thermal decomposition of these compounds in dynamic dry air atmosphere.

Mixed Ligand Complex Formation of Cetirizine Drug with Bivalent Transition Metal(II) Ions in the Presence of 2-Aminomethylbenzimidazole: Synthesis, Structural, Biological, pH-Metric and Thermodynamic Studies

Mononuclear copper(II), cobalt(II) and nickel(II) complexes of cetirizine (CTZ = 2-[2-[4-[(4-chlorophenyl)phenyl methyl]-piperazine-1-yl]-ethoxy]acetic acid) in the presence of 2-aminomethyl-benzimidazole·2HCl (AMBI), as a representative example of heterocyclic bases, were synthesized and studied by different physical techniques. All mixed-ligand complexes have been fully characterized with the help of elemental analyses, molecular weight determinations, molar conductance, magnetic moments and spectroscopic data. The formulae of the isolated complexes are [M(AMBI)(CTZ)(NO3)(H2O)2]·nH2O where AMBI is the neutral bidentate 2-aminomethylbenzimidazole, CTZ the deprotonated cetirizine and n = 1 for Co(II) or 0 for Cu(II) and Ni(II) complexes. The measured molar conductance values in DMSO indicate that the complexes are non-electrolytes. The formation equilibria of the ternary complexes have been investigated. Ternary complexes are formed by a simultaneous mechanism. Stoichiometry and stability constants for the complexes formed are reported. The concentration distribution of the complexes in solution was evaluated as a function of pH. The thermodynamic parameters were calculated from the temperature dependence of the equilibrium constants and are discussed. The synthesized metal chelates have been screened for their antimicrobial activities against the selected types of Gram-positive (G+) and Gram-negative (G−) bacteria. They were found to be more active against Gram positive than Gram negative bacteria. The antimicrobial activity in terms of metal ions obeys this order: Cu(II) > Ni(II) > Co(II).

Complex formation of cetirizine drug with bivalent transition metal(II) ions in the presence of alanine: synthesis, characterization, equilibrium studies, and biological activity studies

Mononuclear cobalt(II), nickel(II), and copper(II) complexes of cetirizine·2HCl (CTZ = 2-[2-[4-[(4-chlorophenyl)phenyl methyl]piperazine-1-yl]-ethoxy]acetic acid) in the presence of alanine (Ala) as a representative example of amino acids were synthesized and elucidated by different physical techniques. All complexes have been characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments, and spectroscopic data. The measured molar conductance values in DMSO indicate that the complexes are nonelectrolytes. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of complexes. The metal–oxygen bond length in the synthesized complexes obeys the order M–OH2 > M–OCTZ > M–OAla. Formation equilibria of the ternary complexes have been investigated. Ternary complexes are formed by a simultaneous mechanism. Stoichiometry and stability constants for the complexes formed are reported. The concentration distributions of various species formed in solution were also evaluated as a function of pH. CTZ and its metal chelates have been screened for their antimicrobial activities against some selected types of gram-positive (G+) and gram-negative (G−) bacteria. They were more active against (G+) than (G−) bacteria.

Synthesis and Enzymatic Behaviour of Mono- and Dinuclear Complexes of Bivalent Transition Metal Ions with Schiff Base Derived from 2,6-Dibenzoyl-4-methylphenol and 2,6-Diaminopyridine

Synthesis and Enzymatic Behaviour of Mono- and Dinuclear Complexes of Bivalent Transition Metal Ions with Schiff Base Derived from 2,6-Dibenzoyl-4-methylphenol and 2,6-Diaminopyridine

Thermal behavior of malonic acid, sodium malonate and its compounds with some bivalent transition metal ions in dynamic N2 and CO2 atmospheres

Thermal stability and thermal decomposition of malonic acid, sodium malonate and its compounds with Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC) in N 2 and CO 2 atmospheres and TG-FTIR in N 2 atmosphere. The thermal decomposition of malonic acid occurs with decarboxylation followed by the formation of acetic acid in both atmospheres. For sodium malonate the thermal decomposition occurs with formation of sodium carbonate, and for the transition metal malonates the final residue was: MnO (N 2 , CO 2 ),FeO (N 2 ), Fe 3 O 4 (CO 2 ), Co + CoO (N 2 ), CoO (CO 2 ), Ni (N 2 , CO 2 ), Cu (N 2 , CO 2 ) and ZnO (N 2 , CO 2 ).

Chemical Distribution and Structure of Quaternary Metal Chelates in Aqueous Solution Involving Asparagine and Uracil

Ternary and quaternary metal chelates of some biologically important bivalent transition metal ions viz. Co(II), Ni(II), Cu(II) and Zn(II) formed with biologically significant ligands, viz. Asparagine (A) and Uracil (B) have been investigated. The relevant stability constants and complexation equilibria of quaternary metal chelates in solution at 30±1 oC and at constant ionic strength (I=0.1M NaNO3) have been studied potentiometrically. Equilibrium concentrations of all species in multimetal-multiligand system, concentration of each metal and complexing agent have been calculated. Species distribution curves are obtained by plotting percent (%) concentration of the species obtained through SCOGS computer technique against pH. The distribution curves are finally sketched by running the computer program ORIGIN 4.0. The metal ligand formation constant of MA, MB, MAB and M1M2AB type of complexes follow Irving William order. The order of stability constants of quaternary systems has been observed and solution structures of metal complexes with said ligands have been discussed.

Thermal behaviour of nicotinic acid, sodium nicotinate and its compounds with some bivalent transition metal ions

Solid-state M(L)2·nH2O compounds, where M stands for bivalent transition metals (Mn, Fe, Co, Ni, Cu and Zn), L is nicotinate and n=0–4.5, have been synthesized. Characterization and thermal behaviour of these compounds were investigated employing elemental analysis based on the mass losses observed in the TG–DTA curves, complexometry, X-ray diffractometry, infrared spectroscopy (FTIR), simultaneous thermogravimetric and differential thermal analysis (TG–DTA) and TG–DSC coupled to FTIR. The thermal behaviour of nicotinic acid and its sodium salt was also investigated. For the hydrated transition metal compounds, the dehydration and thermal decomposition of the anhydrous compounds occur in a single step. For the sodium nicotinate, the final residue up to 765°C is sodium carbonate and for the transition metal nicotinates, the final residues are Mn3O4, Fe2O3, Co3O4, NiO, CuO and ZnO. The results also provided information concerning the thermal stability, thermal decomposition and identification of the gaseous products evolved during the thermal decomposition of the compounds.

Potentiometric and Thermodynamic Studies of Binary and Ternary Transition Metal(II) Complexes of Imidazole-4-acetic Acid and Some Bio-relevant Ligands

Proton–ligand association constants of imidazole-4-acetic acid (IMA) were determined potentiometrically in aqueous solution at different temperatures in the range 15–35 °C. The stepwise stability constants of IMA with some selected bivalent transition metal ions were also determined in 0.1 mol·dm−3 NaNO3. The stability of the complexes follows the trend Cu2+ > Ni2+ > Co2+ > Mn2+, which is in agreement with the Irving–Williams order of the metal ions. The thermodynamic parameters for Cu(II)–IMA complex formation were derived and discussed. The ternary complexes Cu(IMA)L (IMA = imidazole-4-acetic acid, HL = amino acid, amides or DNA constituents) have been investigated. Ternary complexes of amino acids or amides are formed by a simultaneous mechanism. Amino acids form the complex Cu(IMA)L, whereas amides form two complex species Cu(IMA)L and Cu(IMA)(LH−1). The DNA constituents form both 1:1 and 1:2 complexes. The stabilities of ternary complexes are quantitatively compared with their corresponding binary complexes. The concentration distribution of the complexes in solution was evaluated as a function of pH.

Thermal behaviour of α-hydroxyisobutyric acid, sodium α-hydroxyisobutyrate and its compounds with some bivalent transition metal ions

Synthesis, characterization and thermal decomposition of bivalent transition metal α-hydroxyisobutyrates, M(C4H7O3)2·nH2O (M=Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II)), as well as the thermal behaviour of α-hydroxyisobutyric acid and its sodium salt were investigated employing simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), infrared spectroscopy (FTIR), TG-DSC coupled to FTIR, elemental analysis and complexometry. All the compounds were obtained as dihydrated, except the copper one which was obtained in the anhydrous state. The thermal decomposition of the anhydrous compounds occurs in a single or two steps and the final residue up to 235°C (Mn), 300°C (Fe), 305°C (Co), 490°C (Ni), 260°C (Cu) and 430°C (Zn) is Mn2O3, Fe2O3, Co3O4, NiO, CuO and ZnO, respectively. The results also provided information concerning the ligand's denticity and identification of the gaseous products evolved during the thermal decomposition of these compounds.

‘One-pot’ synthesis of multi-ring heteroaromatic compounds involving a pair of imidazo[1,5-a]pyridine moiety: reporting an interesting bis-bidentate ligand capable of forming helicates

‘One-pot’ synthesis of nitrogenous heterocyclic compounds (1 and 2) containing a pair of biologically relevant imidazo[1,5-a]pyridine moiety has been reported; compound 1 being a planar molecule, shows enough flexibility during its coordination to bivalent transition metal ions forming, for example, a triple stranded helicate with copper(II).

Thermal behaviour of mandelic acid, sodium mandelate and its compounds with some bivalent transition metal ions

Characterization, thermal stability and thermal decomposition of transition metal mandelates, M(C6H5CH(OH)CO2)2 (M=Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), as well as the thermal behaviour of mandelic acid C6H5CH(OH)CO2H and its sodium salt were investigated employing simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC), TG–DSC coupled to FTIR, infrared spectroscopy (FTIR), elemental analysis and complexometry. All the compounds were obtained in the anhydrous state and the thermal decomposition occurs in two or four consecutive steps. The final residue up to 320°C (Mn), 345°C (Fe), 400°C (Co), 405°C (Ni), 355°C (Cu) and 575°C (Zn) is Mn3O4, Fe2O3, Co3O4, NiO, CuO and ZnO, respectively. The results also provided information concerning the ligand's denticity, thermal behaviour and identification of gaseous products evolved during the thermal decomposition of these compounds.

Synthesis, characterization and thermal study of solid mandelate of some bivalent transition metal ions in CO2 and N2 atmospheres

Solid state M-L, where M stands for bivalent transition metals (Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)) and L is mandelate, were synthesized. Simultaneous thermogravimetry and differential scanning calorimetry, elemental analysis and complexometry were used to establish the stoichiometry and to study the thermal behaviour of these compounds in CO2 and N2 atmospheres. The results show that all the compounds were obtained in the anhydrous state and in agreement with the general formula ML2. The thermal decomposition of the compounds occurs in a single (Cu(II)), two (Ni(II)) three (Fe(II), Co(II)), four (Mn(II)) and five (Zn(II)) steps. The results also provided information concerning the ligand’s denticity, thermal behaviour, final residues and identification of gaseous products evolved during the thermal decomposition of these compounds.

Two Novel Purely Inorganic Coordination Polymers Constructed From Bivalent Transition Metal Ions and Paratungstate Clusters

The new polymeric compounds (NH4)8[Cu(H2O)2H2W12O42]·10H2O (1) and (NH4)4[Co(H2O)2][Co(H2O)4]2[H2W12O42]·8H2O (2) have been synthesized in aqueous solution and characterized by elemental analysis, TG analysis. Single crystal X-ray diffraction revealed that the [H2W12O42]10− (named paratungstate-B) units act as tetradentate and octadentate ligands, respectively. In compound 1, two neighboring paratungstate-B clusters are linked by [Cu(H2O)2]2+ units leading to the formation of 1D chain. In crystal of 2, each cobalt ion links two paratungstate-B clusters, while each [H2W12O42]10− block is surrounded by two [Co(H2O)2]2+ and four [Co(H2O)4]2+ bridging cations resulting a 2D sheet formed parallel to the $$ [10\bar{1}] $$ plane. Each [H2W12O42]10− cluster is linked via two uniform [Co(H2O)4]2+ (Co2) bridging groups to form a 1D double-chain along the b axis. The chains are then connected via [Co(H2O)2]2+ (Co1) to form 2D layered networks parallel to the $$[10\bar{1}]$$ plane.

Thermal and spectroscopic data to investigate the oxamic acid, sodium oxamate and its compounds with some bivalent transition metal ions

Abstract Synthesis, characterization, and thermal behavior of transition metal oxamates, M(NH2C2O3)2·nH2O (M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II)), as well as the thermal behavior of oxamic acid and its sodium salt (NaNH2C2O3) were investigated employing simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), experimental and theoretical infrared spectroscopy, TG-DSC coupled to FTIR, elemental analysis and complexometry. The results led to information about the composition, dehydration, thermal stability, thermal decomposition, as well as of the gaseous products evolved during the thermal decomposition of these compounds in dynamic air and N2 atmospheres.

Thermal behaviour of succinic acid, sodium succinate and its compounds with some bivalent transition metal ions

Characterization, thermal stability and thermal decomposition of transition metal succinates, MC 2H 4C 2O 4· nH 2O (M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II)), the thermal behaviour of succinic acid (C 4H 6O 4) and its sodium salt (Na 2C 2H 4C 2O 4·6H 2O) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG–DTA), differential scanning calorimetry (DSC), infrared spectroscopy, TG–FTIR system, elemental analysis and complexometry. For the hydrated compounds the dehydration and the thermal decomposition of the anhydrous compounds occur in a single step. For the sodium succinate the final residue up to 545 °C is sodium carbonate, while the transition metal succinates the final residues are Mn 3O 4, Fe 2O 3, Co 3O 4, NiO, CuO and ZnO, respectively. The results also provided information concerning the thermal behaviour and identification of gaseous products evolved during the heating of these compounds.