Comprehensive study on the solvation of mono- and divalent metal cations: Li+, Na+, K+, Be2+, Mg2+ and Ca2+

Hydration of mono- and divalent metal ions (Li(+), Na(+), K(+), Be(2+), Mg(2+) and Ca(2+)) has been studied using the DFT (B3LYP), second-order M?ller-Plesset (MP2) and CCSD(T) perturbation theory as well as the G3 quantum chemical methods. Double-zeta and triple-zeta basis sets containing both (multiple) polarization and diffuse functions were applied. Total and sequential binding energies are evaluated for all metal-water clusters containing 1-6 water molecules. Total binding energies predicted at lower levels of theory are compared with those from the high level G3 calculations, whereas the sequential binding energies are compared with available experimental values. An increase in the quality of the basis set from double-zeta to triple-zeta has a significant effect on the sequential binding energies, irrespective of the geometries used. Within the same group (I or II), the sequential binding energy predictions at the MP2 and B3LYP vary appreciably. We noticed that, for each addition of a water molecule, the change of the M-O distance in metal-water clusters is higher at the B3LYP than at the MP2 level. The charge of the metal ion decreases monotonically as the number of water molecules increase in the complex.     

Theoretical study of interaction of 2,6-dithiopurine with Li+, Na+, K+, Be2+, Mg2+, and Ca2+ metal cations

The geometries of the complexes of Li⁺, Na⁺, K⁺, Be²⁺, Mg²⁺, and Ca²⁺ metal cations with different possible 2,6-dithiopurine anions (DTP) were studied. The complexes were optimized at the B3LYP level and the 6-311++G(d, p) basis set. The interactions of the metal cations at different nucleophilic sites of various possible 2,6-dithiopurine anions were considered. It was revealed that metal cations would interact with 2,6-dithiopurine anions in a bicoordinate manner. In the gas phase, the most preferred position for the interaction of Li⁺, Na⁺, and K⁺ cations is between the N₃ and S₂ sites, while all divalent cations Be²⁺, Mg²⁺, and Ca²⁺ prefer binding between the N₇ and S₆ sites of the corresponding 2,6-dithiopurine. The influence of aqueous solvent on the relative stability of different complexes has been examined using the Tomasi’s polarized continuum model. The basis set superposition error (BSSE) corrected interaction energy was also computed for complexes. The AIM theory has been applied to analyze the properties of the bond critical points (electron densities and their Laplacians) involved in the coordination between 2,6-dithiopurine anions and the metal cations. It was revealed that aqueous solution would have significant effect on the relative stability of complexes obtained by the interaction of 2,6-dithiopurine anions with Mg²⁺ and Ca²⁺ cations. The effect of metal cations on different NH and CS stretching vibrational modes of 2,6-dithiopurine has also been discussed.     

Transport of Ca2+, Sr2+, Ba2+, Na+, K+ and Cs+ through hollow fiber supported liquid membrane

The transport of metal ions (Ca²⁺, Sr²⁺, Ba²⁺, Na⁺, K⁺, Cs⁺) through hollow fiber supported dichlorobenzene liquid membrane has been studied. The transport of cations using 8-crown-6 ether as a carrier and picrate as co-counter ion as well as a pertraction device and capillary isotachophoresis (ITP) measurement of the cation concentration is described.     

Cation [M = H+, Li+, Na+, K+, Ca2+, Mg2+, NH4+, and NMe4+] interactions with the aromatic motifs of naturally occurring amino acids: a theoretical study

Ab initio (HF, MP2, and CCSD(T)) and DFT (B3LYP) calculations were done in modeling the cation (H(+), Li(+), Na(+), K(+), Ca(2+), Mg(2+), NH(4)(+), and NMe(4)(+)) interaction with aromatic side chain motifs of four amino acids (viz., phenylalanine, tyrosine, tryptophan and histidine). As the metal ion approaches the pi-framework of the model systems, they form strongly bound cation-pi complexes, where the metal ion is symmetrically disposed with respect to all ring atoms. In contrast, proton prefers to bind covalently to one of the ring carbons. The NH(4)(+) and NMe(4)(+) ions have shown N-H...pi interaction and C-H...pi interaction with the aromatic motifs. The interaction energies of N-H...pi and C-H...pi complexes are higher than hydrogen bonding interactions; thus, the orientation of aromatic side chains in protein is effected in the presence of ammonium ions. However, the regioselectivity of metal ion complexation is controlled by the affinity of the site of attack. In the imidazole unit of histidine the ring nitrogen has much higher metal ion (as well as proton) affinity as compared to the pi-face, facilitating the in-plane complexation of the metal ions. The interaction energies increase in the order of 1-M < 2-M < 3-M < 4-M < 5-M for all the metal ion considered. Similarly, the complexation energies with the model systems decrease in the following order: Mg(2+) > Ca(2+) > Li(+) > Na(+) > K(+) congruent with NH(4)(+) > NMe(4)(+). The variation of the bond lengths and the extent of charge transfer upon complexation correlate well with the computed interaction energies.     

H+, Li+, and Na+ affinity study of N2, P2, and their isoelectronic species

We performed ab initio calculations for protonated P₂, N₂, NP, and their isoelectronic species, i.e., CO, CS, SiO, and SiS. The proton affinities at different sites were examined to characterize special properties of the second-row elements. To tune the acid strength, we also studied the Li⁺ and Na⁺ affinities for comparison. These systems are isovalent to acetylene and disilyne; their structural features such as linear or bent is of special interest. All calculations were performed by the GAUSSIAN 92 program using the 6-31G** basis set and the basis set at the Hartree-Fock and MP2(full) levels. Bent structures were found for XP⁺₂, CSH⁺, and SiSX (X = H⁺, Li⁺, Na⁺). © 1996 John Wiley & Sons, Inc.     

啤酒酵母生理代谢过程中钠、钾、镁、钙离子含量变化的跟踪检测

采用空气-乙炔火焰原子吸收光谱法分别测定了啤酒酵母发酵液中的Na^ 、K^ 、Mg^2 、Ca^2 离子动态变化中的含量,用La^3 盐消除P对Ca^3 的干扰,以Sr^2 盐作为Na^ 、K^ 的消电离剂。本实验室采用配制培养基,通过对不同种类及不同发酵阶段培养的发酵液样品进行测定,以研究在啤酒酵母生长代谢过程中Na^ 、K^ 、Mg^2 、Ca^2 离子代谢动态变化。方法的Na^ 、K^ 、Mg^2 、Ca^2 相对标准偏差(RSD)分别为0．31％,0．73％。1．78％,0．28％;样品加标回收率为98％-107％;检出限：Na^ 为0．159mg／L,K^ 为0．789nag／L,Mg^2 为0．039mg／L,Ca^2 为0．029mg／L。该方法简便快速,具有很好的精密度。     

Switching between molecular switch types by module rearrangement: Ca2+-enabled, H+-driven 'Off-On-Off', H+-driven YES and PASS 0 as well as H+, Ca2+-driven AND logic operations

Several logic gates and switches can be accessed from two different combinations of a single set of fluorophore, receptor and spacer components.     

Correlated ab initio quantum chemical study of the interaction of the Na+, Mg2+, Ca2+, and Zn2+ ions with the tautomers of cytosine

The interaction of the metal ions Na(+), Mg(2+), Ca(2+), and Zn(2+) with cytosine have been reinvestigated at the density functional, M?ller-Plesset, and coupled cluster levels of theory, including hitherto unstudied tautomeric forms. It has been found that the interaction of the metal ion has a varying and often significant effect on the stabilities of the various tautomers, in some cases making most stable rare tautomeric forms. The results have been analyzed with respect to method and role of ion in binding, and confirm that, as has been found for the base cytosine tautomers, B3LYP does not give energetics consistent with highly accurate post-SCF methods for their interaction with these metal ions.     

Understanding the inactivation process of organophosphorus herbicides: A DFT study of glyphosate metallic complexes with Zn2+, Ca2+, Mg2+, Cu2+, Co3+, Fe3+, Cr3+, and Al3+

Glyphosate is the active component of one of the top‐selling herbicides, which is also a potent EPSP synthase inhibitor. The herbicide is absorbed by living tissue and translocated via the phloem, to plant roots and rhizomes. When applied directly into the soil it has low activity, due to the high adsorption by soil constituents. Understanding the specific interactions between metals in the soil and glyphosate is the main step in understanding the low activity of the herbicide when applied directly into the ground and not pulverized. We can observe there is a stability order for both tetrahedral and octahedral complexes between glyphosate and metals: Zn>Cu>Co>Fe>Cr>Al>Ca>Mg. © 2012 Wiley Periodicals, Inc.     

Effect of metal ions (Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) and water coordination on the structure of glycine and zwitterionic glycine

Interactions between metal ions and amino acids are common both in solution and in the gas phase. Here, the effect of metal ions and water on the structure of glycine is examined. The effect of metal ions (Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) and water on structures of Gly.Mn+(H2O)m and GlyZwitt.Mn+(H2O)m (m = 0, 2, 5) complexes have been determined theoretically by employing the hybrid B3LYP exchange-correlation functional and using extended basis sets. Selected calculations were carried out also by means of CBS-QB3 model chemistry. The interaction enthalpies, entropies, and Gibbs energies of eight complexes Gly.Mn+ (Mn+ = Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) were determined at the B3LYP density functional level of theory. The computed Gibbs energies DeltaG degrees are negative and span a rather broad energy interval (from -90 to -1100 kJ mol(-1)), meaning that the ions studied form strong complexes. The largest interaction Gibbs energy (-1076 kJ mol(-1)) was computed for the NiGly2+ complex. Calculations of the molecular structure and relative stability of the Gly.Mn+(H2O)m and GlyZwitt.Mn+(H2O)m (Mn+ = Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+; m = 0, 2, and 5) systems indicate that in the complexes with monovalent metal cations the most stable species are the NO coordinated metal cations in non-zwitterionic glycine. Divalent cations Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+ prefer coordination via the OO bifurcated bonds of the zwitterionic glycine. Stepwise addition of two and five water molecules leads to considerable changes in the relative stability of the hydrated species. Addition of two water molecules at the metal ion in both Gly.Mn+ and GlyZwitt.Mn+ complexes reduces the relative stability of metallic complexes of glycine. For Mn+ = Li+ or Na+, the addition of five water molecules does not change the relative order of stability. In the Gly.K+ complex, the solvation shell of water molecules around K+ ion has, because of the larger size of the potassium cation, a different structure with a reduced number of hydrogen-bonded contacts. This results in a net preference (by 10.3 kJ mol(-1)) of the GlyZwitt.K+H2O5 system. Addition of five water molecules to the glycine complexes containing divalent cations Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+ results in a net preference for non-zwitterionic glycine species. The computed relative Gibbs energies are quite high (-10 to -38 kJ mol(-1)), and the NO coordination is preferred in the Gly.Mn+(H2O)5 (Mn+ = Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) complexes over the OO coordination.     

Effect of metal ions (Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) and water coordination on the structure and properties of L-arginine and zwitterionic L-arginine

Interactions between metal ions and amino acids are common both in solution and in the gas phase. The effect of metal ions and water on the structure of L-arginine is examined. The effects of metal ions (Li(+), Na(+), K(+), Mg(2+), Ca(2+), Ni(2+), Cu(2+), and Zn(2+)) and water on structures of Arg x M(H2O)m , m = 0, 1 complexes have been determined theoretically by employing the density functional theories (DFT) and using extended basis sets. Of the three stable complexes investigated, the relative stability of the gas-phase complexes computed with DFT methods (with the exception of K(+) systems) suggests metallic complexes of the neutral L-arginine to be the most stable species. The calculations of monohydrated systems show that even one water molecule has a profound effect on the relative stability of individual complexes. Proton dissociation enthalpies and Gibbs energies of arginine in the presence of the metal cations Li(+), Na(+), K(+), Mg(2+), Ca(2+), Ni(2+), Cu(2+), and Zn(2+) were also computed. Its gas-phase acidity considerably increases upon chelation. Of the Lewis acids investigated, the strongest affinity to arginine is exhibited by the Cu(2+) cation. The computed Gibbs energies DeltaG(o) are negative, span a rather broad energy interval (from -150 to -1500 kJ/mol), and are appreciably lowered upon hydration.     

Structural and electronic properties of complexes between Li+, Na+, Be2+, and Mg2+ ions and HF,H2O,and NH3 molecules

Theoretical and Experimental Chemistry -     

Theoretical studies on the interaction of anionic collectors with Cu+, Cu2+, Zn2+ and Pb2+ ions

 The influence of collector structure on interaction with metal cations was modelled by computational ab initio methods. The interaction energies were calculated between metal ions (Cu⁺, Cu²⁺, Zn²⁺ and Pb²⁺) and selected collector anions: ethyl xanthate, ethyl trithiocarbonate, dithiobutyric acid, ethyl dithiocarbamate, diethyl dithiocarbamate, diethylphosphinecarbodithioic acid and diethoxyphosphinecar bodithioic acid. The strongest interaction was found with diethyl dithiocarbamate. The results give qualitative information on the effect of the collector structure on the initial adsorption steps on sulphide mineral flotation. Received: 25 September / Accepted: 11 October 2001 / Published online: 22 March 2002     

Ionophoric properties of atropine: complexation and transport of Na+, K+, Mg2+ and Ca2+ ions across a liquid membrane

The activity of atropine on the complexation and transport of Na(+), K(+), Mg(2+) and Ca(2+) ions across a liquid membrane was investigated using a spectrophotometric method. Atropine is a natural drug that blocks muscarinic receptors. It is a competitive antagonist of the action of acetylcholine and other muscarinic agonists. Atropine is shown to extract Na(+), K(+), Mg(2+) and Ca(2+) ions from an aqueous phase into an organic one with a preference for Ca(2+) ions. According to a kinetic study, divalent cations (Mg(2+) and Ca(2+)) are more rapidly transported than monovalent ones (Na(+) and K(+)). In both complexation and transport, the flux of the ions increases with the increase of atropine concentration. Atropine might act on the membrane permeability; its complexation and ionophoric properties shed new lights on its therapeutic properties.     

Napthaquinone derived ionophores: interaction with biologically important metal ions (Li+, Na+, K+, Mg2+ and Ca2+)

The synthetic model systems based on the study of supramolecular compounds are proficient in mimicking the biological processes so as to get the insight of their processes. In this perspective, a series of naphthaquinone derived redox switchable ionophores namely D₁ (2,3,5,6,8,9,11,12-octahydronaphtho [2,3b] [1,4,7,10,13] pentaoxacyclo octadecine-14,19-dione) and D₂ (2,3,5,6,8,9-hexahydronaphtho[2,3-b] [1,4,7,10] tetraoxacyclododecine-11,16-dione) have been synthesized and interacted with Li⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺ cations. The isolated solid state soft materials obtained after interaction were characterized by melting point, TLC, ¹H NMR spectroscopy and CHN estimation. The extraction, transport potential and stability constant determination of these ionophores towards cations helped in investigating their binding strength in solution. The selective extraction of Na⁺ and Li⁺ by D₁ and D₂ correspondingly proves them an efficient compound for the manufacturing of chemosensor. Whereas efficient transport of Mg²⁺ by both the ionophores especially by D₁ may assist in developing biomodels for understanding its transport through membrane in living system. The selectivity of these ionophores towards metal ions can be modulated by molecular tailoring.