Sodium Coordination Research Articles

Fabricating Bis(phthalocyaninato) Terbium SIM into Tetrakis(phthalocyaninato) Terbium SMM with Enhanced Performance through Sodium Coordination.

The non-peripherally substituted 1,4,8,11,15,18,22,25-octa(butoxy)-phthalocyanine-involved unsymmetrical heteroleptic bis(phthalocyaninato) terbium double-decker, Tb(Pc){H[Pc(α-OC4 H9 )8 ]} (Pc=unsubstituted phthalocyanine) (1), was revealed to exhibit typical single ion magnet (SIM) behavior with effective energy barrier, 180 K (125 cm-1 ), and blocking temperature, 2 K, due to the severe deviation of the terbium coordination polyhedron from square-antiprismatic geometry. Fabrication of this double-decker compound into the novel tetrakis(phthalocyaninato) terbium pseudo-quadruple-decker Na2 {Tb(Pc)[Pc(α-OC4 H9 )8 ]}2 (2) single molecule magnet (SMM) not only optimizes the coordination polyhedron of terbium ion towards the square-antiprismatic geometry and intensifies the coordination field strength, but more importantly significantly enhances the molecular magnetic anisotropy in the unsymmetrical bis(phthalocyaninato) double-decker unit, along with the change of the counter cation from H+ of 1 to Na+ of 2, leading to an significantly enhanced magnetic behavior with spin-reversal energy barrier, 528 K (367 cm-1 ), and blocking temperature, 25 K. The present result is surely helpful towards developing novel tetrapyrrole lanthanide SMMs through rational design and self-assembly from bis(tetrapyrrole) lanthanide single ion magnet (SIM) building block.

Synthesis and characterization of unique new lithium, sodium and potassium coordination polymers

Abstract Five new alkali metal coordination compounds [Li(NPG)](1a), [Na(NPG)2]⋅2H2O(2a), [C8H5KO4](3a), [Li(NPA)2H2O](1b) and [Na(NPA)2](2b) wherein (NPG = N-phthaloyl glycine, NPA = N-phthaloyl-s-alanine) have been synthesized and characterized by means of X ray single crystal analysis, Infrared spectroscopy (IR), Thermogravimetric analysis (TGA) and Florescence spectroscopy. The compounds 1a, 2a, 3a and 2b showed metal directed self-assembly supramolecular network structures. The crystal structure of compounds 1a and 1b showed distorted tetrahedral geometry with coordination number 4 around lithium. The carboxylate coordination modes were η2µ3and η1µ1 in 1a and 1b respectively. The compounds 2a and 2b exhibited distorted octahedral geometry with coordination number 6 around sodium. The carboxylate coordination mode in 2a and 2b is η2µ2. The objective was to synthesize potassium complex [K(NPG)], but N-phthaloyl glycine was hydrolysed due to exothermic reaction in the presence of strong base, resulted, the formation of 3a. The multiple coordination modes of alkali metal ions to the carboxylate and ring carbonyl oxygen atoms of NPG and NPA produced unique three dimensional architectures. The compounds 1b and 2b showed two strong fluorescence emissions enhancement (blue emission maxima) with greater intensity comparative to NPA, while the compounds 1a and 2a showed two weak fluorescence emissions with less intensity comparative to ligand (NPG). The base hydrolysis of NPG with in the compound 3a resulted the change of ligand based fluorochrome, which produced different shape emission spectrum as compared to other compounds.

Irreversible replacement of sodium with thallium in sodium coordination polymer nanostructures by solid-state mechanochemical cation exchange process

Solid-state conversion of NaI coordination polymer nanostructure, synthesized by sonochemical procedure, to TlI coordination polymer has been observed upon liquid-assisted mechanochemical reaction of [Na2TP] n (1) (H2TP = terephthalic acid), with TlNO3. During this conversion, ion exchange process of Na(I) with Tl(I) was occurred and [Tl2TP] n (2) was synthesized. The X-ray diffraction (XRD) pattern of 2 after mechanochemical reaction of it with NaNO3 indicated that this transformation is irreversible. Compounds 1 and 2 were characterized by IR spectroscopy, X-ray powder diffraction (XRD), elemental analysis, thermogravimetric and differential thermal analyses and scanning electron microscopy.

Structural Connection between Activation Microswitch and Allosteric Sodium Site in GPCR Signaling

Sodium ions are endogenous allosteric modulators of many G-protein-coupled receptors (GPCRs). Mutation of key residues in the sodium binding motif causes a striking effect on G-protein signaling. We report the crystal structures of agonist complexes for two variants in the first sodium coordination shell of the human A2A adenosine receptor, D522.50N and S913.39A. Both structures present an overall active-like conformation; however, the variants show key changes in the activation motif NPxxY. Changes in the hydrogen bonding network in this microswitch suggest a possible mechanism for modified G-protein signaling and enhanced thermal stability. These structures, signaling data, and thermal stability analysis with a panel of pharmacological ligands provide a basis for understanding the role of the sodium-coordinating residues on stability and G-protein signaling. Utilizing the D2.50N variant is a promising method for stabilizing class A GPCRs to accelerate structural efforts and drug discovery.

Solid-state mechanochemical conversion of one-dimensional pencil shaped sodium coordination polymer nanorods to corrugated tape silver coordination polymer nanoparticles

Irreversible solid-state conversion of pencil shaped Na coordination polymer nanorods, prepared by sonochemical procedure, to nanoparticles of corrugated tape silver polymer has been observed upon mechanochemical reaction of compound [Na(μ2-Hdcpa)(μ3-dcpa)]n (1), [Hdcpa=2,4-dichlorophenoxyacetic acid] with AgNO3. These nanostructures were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), IR spectroscopy and elemental analyses. Thermal stability of these samples was also studied by thermo gravimetric (TG) and differential thermal analyses (DTA).

Sodium chloride nanorods from nanorods of one-dimensional pencil-shaped sodium coordination polymer

By considering the structure of one-dimensional pencil-shaped organometallic coordination polymer that was previously reported, we designed and synthesized [Na(μ2-Hdcpa)(μ3-dcpa)]n (1), [Hdcpa = 2,4-dichlorophenoxyacetic acid], which has one-dimensional pencil-shaped structure too. The Na atoms are surrounded with the aromatic phenyl rings of Hdcpa similar to graphite of a pencil. Metalophilic interactions also exists in 1 between Na(I) ions similar to argentophilic interaction in our previous compound which results in formation of chain structure similar to graphite structure of a pencil. Compound 1 nanorods were formed under ultrasonic irradiation and applied as template to fabricate sodium chloride nanorods. The interesting feature of our work is the formation of sodium chloride nanorods from compound 1 nanorods which have one-dimensional structure in the solid state.

Molecular dynamic simulations of glycine amino acid association with potassium and sodium ions in explicit solvent

Salt solutions are the natural environment in which biological molecules act, and dissolved ions are actively involved in biochemical processes. With metal ions, the membrane potentials are maintained. Ions are crucial for the activity of many enzymes, and their ability to coordinate with chemical groups modulates protein-protein interactions. Here we present a comparative study of sodium and potassium coordination with zwitterionic glycine, by means of explicit solvent molecular dynamics. We demonstrated that contact ion pair of cations and carboxylate group splits into two distinct coordination states. Sodium binding is significantly stronger than for potassium. These results can shed light on the different roles of sodium and potassium ions in abiogenic peptide synthesis.

Reversible liquid assisted mechanochemical conversion of sodium coordination polymer nanorods to organosilver coordination polymer nanosheets

Reversible solid-state structural transformation of sodium(I) coordination polymer nanorods, prepared by sonochemical procedure, to organosilver coordination polymer nanosheets has been observed upon liquid assisted mechanochemical reaction of compound [Na2(1,5-nds)(H2O)2]n (1), [1,5-H2nds=1,5-naphthalenedisulfonic acid] with AgNO3. During this conversion, two coordinated H2O molecules were removed from 1 and substituted with two carbon atoms from 1,5-nds2− ligand in 2. Thus organosilver coordination polymer of 2 was formed during this conversion and distorted trigonal-bipyramidal coordination geometry in 1 with NaO5 coordination sphere was converted to distorted tetrahedral geometry in 2 (regarding the CC group as one donor) with AgO3C2 coordination sphere.

Solid-state conversion of a three-dimensional sodium(I) coordination polymer with micro trigon morphology to two-dimensional silver(I) coordination polymer nanostructures

The solid-state conversion of a NaI coordination polymer with a micro trigon morphology, synthesized by a sonochemical procedure, to AgI coordination polymer nanostructures has been observed upon mechanochemical reaction of the compound [Na2(OBA)(H2O)]n (1), [H2OBA=4,4′-oxybis(benzoic acid)] with AgNO3. During this conversion, one coordinated H2O molecule was removed and two types of Na atoms were replaced with one type of Ag atom in [Ag2(OBA)]n (2). In addition, the OBA2− ligand, with μ8 coordination mode in 1, showed a μ6 coordination mode in 2. The angle of the two aromatic rings of the OBA2− ligand is changed from 57.03° in 1 to 59.46° in 2. IR spectroscopy, X-ray powder diffraction (XRD) and thermo gravimetric and differential thermal analyses (TG–DTA) indicated that this conversion is irreversible.

Dual Sensing By Simple Heteroditopic Salt Receptors Containing an Anthraquinone Unit

We synthesized simple ion pair receptors consisting of a crown ether cation binding site and an anthraquinone supported thiourea anion binding domain and studied their anion, cation and salt binding properties using spectroscopic, spectrophotometric and electrochemical measurements in acetonitrille solution. Apart from carboxylate anions, which cause deprotonation all the anions tested were found to associate with receptors more strongly in the presence of sodium cations, whereas in the presence of potassium or ammonium cation the anion binding strength was greatly diminished. A homotopic anion receptor lacking a crown ether unit, was unable to bind sodium salt more strongly than tetrabutylammonium salts. Solution and solid state X-ray measurements revealed that strong sodium coordination with the cation binding domain is responsible for the salt binding enhancement. Electrochemical measurements showed that the addition of anions to the ditopic ion pair receptors pretreated with sodium cations resulted in greater changes in reduction potentials compared to the addition of anions to receptors in the absence of Na+. Karbarz, M.; Romanski, J. Inorg. Chem. 2016, 55, 3616-3623. Figure 1

1D Structure Sodium Coordination Anion based on [5‐(Dinitromethylene)‐4,5‐dihydro‐1H‐tetrazole]: Syntheses, Structures, and Thermal Behavior

AbstractThe ten‐coordinate complex, (HATr)[Na(DNMz)]·H2O (1) was synthesized by reaction of 5‐(dinitromethylene)‐4,5‐dihydro‐1H‐tetrazole (DNMz), sodium hydroxide, and 3‐hydrazinium‐4‐amino‐1,2,4‐1H‐triazolium dichloride (HATr) in aqueous solution and characterized by various physico‐chemical techniques. Complex 1 is an energetic material with a nitrogen content of 51.2 % and a decomposition temperature of 128.9 °C. The molecular structure of complex 1 crystallizes in the monoclinic system with P2(1)/c group and shows an infinite 1D chain structure. The heat of formation was determined as –122.27 kJ·mol–1 by using bomb calorimetry. In addition, the kinetic parameters were studied by Kissinger's and Ozawa‐Doyle's methods.

Dual Sensing by Simple Heteroditopic Salt Receptors Containing an Anthraquinone Unit.

We synthesized simple ion pair receptors consisting of a crown ether cation binding site and an anthraquinone-supported thiourea anion binding domain and studied their anion-, cation-, and salt-binding properties using spectroscopic, spectrophotometric, and electrochemical measurements in acetonitrile solution. Apart from carboxylate anions, which cause deprotonation, all the anions tested were found to associate with receptor 1 more strongly in the presence of sodium cations, whereas in the presence of potassium or ammonium cation the anion binding strength was greatly diminished. A homotopic anion receptor 3, lacking a crown ether unit, was unable to bind sodium salt more strongly than tetrabutylammonium salts. Solution and solid-state X-ray measurements revealed that strong sodium coordination with the cation-binding domain is responsible for the salt-binding enhancement. Electrochemical measurements showed that the addition of anions to the receptor 1 pretreated with sodium cations resulted in greater changes in reduction potentials compared to the addition of anions to receptor 1 in the absence of Na(+).

Synthesis, Crystal Structure and Spectroscopic Analysis of a New Sodium Coordination Polymer

AbstractA new sodium coordination polymer, [Na2(L)2(H2O)4]n(1), was synthesized by reflux reaction ofp-aminobenzene sulfonic acid,p-hydroxy benzaldehyde and NaOH in ethanol/water solution and characterized by elemental analysis, UV-vis, IR and X-ray single crystal diffraction analysis. The crystal of 1 belongs to monoclinic, space groupP21/cwitha= 17.765(4) Å,b=10.181(2) Å,c= 8.0450(16) Å,β= 91.67(3)°,V= 1454.5(5) Å3,Z= 4,Dc= 1.531 mg·,μ= 0.28 mm-1,F(000) = 696, and finalR1= 0.0327,ωR2= 0.0854. The molecules of 1 are extended to a 2D layer structure alongabplane. The 2D layers form 3D framework structure by the interaction of π-π stacking and hydrogen-bond interaction.

Density effects on the structure of irradiated sodium borosilicate glass: A molecular dynamics study

We have carried out Molecular Dynamics simulations on a sodium borosilicate glass in order to analyze how the structure of the glass during irradiation is affected by the choice of the density in the liquid state before cooling. In a pristine form generated through the usual melt-and-quench method, both short- and medium-range structures are affected by the compressive or tensile environment under which the glass model has been generated. Furthermore, Na-rich areas are much easier to compress, producing a more homogeneous glass, in terms of density, as we increase the confinement during the quench. When the glass is subjected to displacement cascades, the structural modifications saturate at a deposited energy of approximately 8eV/atom. Swelling appears for the glasses that were initially prepared under compression, while contraction is evident for the ones prepared under tension. We have equally prepared glass models using a fast quench method, and we have found that they present an analogous disorder as the glasses submitted to displacement cascades. Compared to the irradiated glass, we found that the magnitude of the modifications for the fast quenched glass is lower, most notably in terms of boron and sodium coordination, the percentage of non-bridging oxygens and in the ring distributions. This later result agrees with statements extracted from recent experimental works on nuclear glasses.

Structural and Electrochemical Characterization of New Hexagonal Form of NaMn2O4 Cathodes for Sodium Ion Batteries

Introduction Lithium ion batteries have thus far been the torchbearers in the field of electrochemical energy storage for mobile applications. The large scale commercialization of lithium ion batteries, however has the associated ‘cost of business’ including possible socio-economic concerns to various lithium rich nations such as Bolivia(1). There has therefore been a gradual realization in the battery community at large for the need to switch to more abundant raw-material based chemistries. Sodium and magnesium batteries are the fore-runners therein(2). In order for the smooth transition and for Na-ion to compete with the Li-ion batteries, considerable improvements in cathode and anode energy density, cyclability and rate capability are still required. Nanocrystalline NaMn2O4 has been synthesized by a high energy mechano-chemical milling process (HEMM) using Na2O2 and Mn2O3 as starting materials for use as cathodes for sodium ion batteries. As previously reported by this group(3), the material exhibits a new close packed hexagonal crystalline form, different from the commonly known stable orthorhombic or monoclinic structures in the Na–Mn–O system, identified for the first time. In this work, we study the stabilization of the hexagonal phase and its evolution to an orthorhombic phase upon heat treatment. Using in-depth solid-state NMR studies in conjunction with detailed electrochemical evaluation, the nature of the charge-storage behavior of this phase is evaluated herein. Figure 1 depicts the evolution of the hexagonal NaMn2O4 to a conventional orthorhombic phase upon heat-treatment. Alteration in sodium co-ordination chemistry and its effect on insertion/deinsertion and capacity will be presented and discussed. Captions Figure 1: Evolution of structure of hexagonal NaMn2O4 into the more known orthorhombic phase upon heat-treatment as observed using scanning electron microscopy.

Alkali environments in tellurite glasses

Neutron diffraction measurements are reported for five binary alkali tellurite glasses, xM2O·(100−x)TeO2 (containing 10 and 20mol% K2O, 10 and 19mol% Na2O, and 20mol% 7Li2O), together with 23Na MAS NMR measurements for the sodium containing glasses. Differences between neutron correlation functions are used to extract information about the local environments of lithium and sodium. The Na–O bond length is 2.37(1) Å and the average Na–O coordination number, nNaO, decreases from 5.2(2) for x=10mol% Na2O to 4.6(1) for x=19mol% Na2O. The average Li–O coordination number, nLiO, is 3.9(1) for the glass with x=20mol% Li2O and the Li–O bond length is 2.078(2) Å. As x increases from 10 to 19mol% Na2O, the 23Na MAS NMR peak moves downfield, confirming an earlier report of a correlation of peak position with sodium coordination number. The close agreement of the maximum in the Te–O bond distribution for sodium and potassium tellurite glasses of the same composition, coupled with the extraction of reasonable alkali coordination numbers using isostoichiometric differences, gives strong evidence that the tellurium environment in alkali tellurites is independent of the size of the modifier cation used.

An in situ high-pressure NMR study of sodium coordination environment compressibility in albite glass

The pressure-dependent modification of the Na-O coordination environment in albite glass is studied in situ to 2 GPa using high-pressure solid-state 23 Na nuclear magnetic resonance spectroscopy. Compression of the glass at ambient-temperature results in shortening of the Na-O bond distance. The concomitant decrease in volume of the local Na-O coordination environment alone can account for the bulk compressibility of albite glass at 300 K. These results provide the first direct experimental evidence of a collapse of the open aluminosilicate framework that helps explain previously reported densification of aluminosilicate glasses and liquids at relatively low pressures without accompanying change in the average coordination number of the network forming Al and Si cations. Such structural changes at relatively low pressures may have far reaching implications for the mechanistic understanding of compressibility and viscosity anomalies characteristic of open tetrahedral aluminosilicate network glasses and melts of geological importance.

Characterisation of Novel Organic Sodium Salts

Growing application of Li-ion and Li-polymer batteries for hybrid electric cars, electric vehicles, mobile devices etc. requires a large amount of lithium in the form of Li2CO3 every year. High price and relatively small world reserves of 13 million tons, forced to look for new materials possible to use in battery technology.That is a clear reason for research effort to find out new types well performed batteries of high energy density, low cost, increased safety and tolerated by the environment. The logical way is to look for lithium analogues with similar chemistry properties and higher resources on the planet (sixth most abundant element and the most abundant alkali metal on Earth).Sodium has molar mass and only slightly lower than lithium red-ox potential (2.73V). Low cost (about 7 times lower than lithium) and enormously easier and almost unlimited worldwide reserves makes him a really promising candidate. Metallic sodium does not form dendrites being a key issue if lithium metallic anodes (with gigantic theoretical capacity of 1190 mAh·g-1) were tested in present batteries. Several secondary advantages only promotes sodium concept for ex. cheaper than aluminum current collectors might be appliedNovel sodium salts, with five-membered ring imidazolium anion, were synthesized. Salts were found extremely stable up to more than 300oC (TGA). Moreover interesting properties of synthesized salts and their solutions in the PC solvent were proven by structural characteristic, electrochemical testing and Raman spectroscopy. NaTDI and NaPDI based electrolytes in PC show good conductivity with the values about 4mScm-1 at 20oC for salt concentration 0.5M and 1M for both salts. Ionic conductivities collected for both salts are almost the same considering slope over temperatures and pure values. Interestingly the high values of the conductivities are reached for 0.5M salt concentrations which is extreme advantage if we consider material savings. Superior properties were also confirmed by Raman spectroscopy used for the ionic association monitoring. Raman spectroscopy showed excellent salts dissociation in carbonate as PC and absence of ion-pairs for concentration up to 0.5M. A long distance framework type ordering of both TDI- and PDI- anions were also observed via extensive X-ray studies (data not presented here). According to previous computional simulations such a superfine structures are suspect to play the crucial role of sodium coordination and by that facilitating substantially cation transport properties. Combining this with thermal stability over 300oC plus the elevated electrochemical stability over 4.5V for NaTDIand 4.2V NaPDI vs Na/Na+ makes these salts interesting as acandidate for electrolyte’s sodium salt carrier.

Nanoindentation studies of simplified nuclear glasses using molecular dynamics

Indentation experiments on complex borosilicate glass used for the immobilization of long-lived radionuclides have demonstrated that its hardness is decreased up to a specific value after being subjected to alpha disintegrations. In this study we have performed multi-million atom nanoindentation simulations using molecular dynamics in order to better understand the atomic mechanisms that produce this decrease. The glasses we selected to simulate are three simplified sodium borosilicates in a pristine form, as well as a “disordered” form, which is analogous to the real irradiated glass. The profiles obtained after the end of the nanoindentation simulations exhibit sink-in for all cases. The calculated hardness values agree with those previously published and were found to follow the decreasing trend which has been experimentally observed after irradiation. These values were found to depend on the composition and more specifically on silica, three-coordinated boron and non-bridging oxygen content. During nanoindentation, silicon atoms retain their coordination numbers, while there is an increase in boron and sodium coordination during loading and a partial reversal during unloading. Finally, nanoindentation induced an increased number of small rings and a decrease of larger ones, the effect being more notable in the case of disordered glasses.

Monometalated tribenzotriquinacene: exo and endo coordination of sodium and potassium with a rigid bowl-shaped hydrocarbon anion.

Treatment of tribenzotriquinacene with trimethylsilylmethyl sodium [NaCH2SiMe3] or potassium hydride [KH] leads to the formation of monometalated products. The sodium atom interacts with the carbanion in an exo fashion, while the potassium atom is found in an endo position inside the rigid bowl-shaped molecule.