Crystallization Water Molecules Research Articles

Poly[[bis-[μ4-3-(2-carboxyl-atophen-yl)propionato]{N-[2-(pyridine-3-amido)-eth-yl]nicotinamide}-dicopper(II)] penta-hydrate

In the title compound, {[Cu2(C10H8O4)2(C14H14N4O2)]·5H2O}n, the CuII cations are coordinated in a square-pyramidal fashion, with four 3-(2-carb-oxy-phen-yl)propionate (cpp) carboxyl-ate O-atom donors in the basal plane, along with an N-atom donor from a N-[2-(pyridin-3-yl-amino)-eth-yl]nicotinamide (pen) ligand in the apical position. [Cu2(cpp)2]n coordination polymer layer motifs with embedded {Cu2(OCO)4} paddlewheel clusters are thereby constructed. These layer motifs are connected into a three-dimensional [Cu2(cpp)2(pen)]n coordination polymer network by tethering pen ligands. Treating the {Cu2(OCO)4 paddelwheel clusters as 6-connected nodes reveals an underlying cross-pillared self-penetrated rob network with 48668 topology. The water mol-ecules of crystallization are held to the coordination polymer network by N-H⋯O and O-H⋯O hydrogen-bonding patterns.

Crystallization and characterization of K2NixCo1-x(SO4)2·6H2O mixed crystals for ultraviolet light filters and sensors

Mixed Tutton salts K2NixCo1-x(SO4)2·6H2O (KNICOSH) single crystals with x = 0, 0.20, 0.50, 0.80 and 1 were grown at 309 K using the slow evaporation of supersaturated aqueous solutions. X-ray diffraction analysis revealed the monoclinic structure, space group P21/a (C_2 h^5) and Z = 2, for each crystal obtained in this work. Thermal investigation showed several peaks that indicated the dehydration process, the exothermic reactions and melting points of K2NixCo1-x(SO4)2·6H2O crystals. The temperatures of these peaks increased with increasing x value, and it means that the crystals rich with Ni have higher thermal stability than those rich with Co. The infrared spectra of KNICOSH crystals showed three types of modes (internal modes of the sulfate ion, internal modes of water and librational modes of water). The wavenumber of internal modes of water increased systematically with increasing Ni content which indicate that the water molecules in KNISH crystal have hydrogen-bonding stronger than that of KCOSH crystal. The wavenumber of other infrared spectra modes changed unsystematically with increasing Ni content. K2Ni0.50Co0.50(SO4)2.6H2O crystal has the most absorption for the light at the visible range while at the ultraviolet region the absorption is low (high transmittance). This behavior enhanced its efficiency for using in ultraviolet light filters and sensors.

ДОСЛІДЖЕННЯ ВПЛИВУ РЕЖИМНИХ ФАКТОРІВ НА КІНЕТИКУ ПРОЦЕСУ ДЕГІДРАТАЦІЇ ЗАЛАЗІ (ІІ) СУЛЬФАТ ГЕПТАГІДРАТУ ФІЛЬТРАЦІЙНИМ МЕТОДОМ

The filtration method of gradual dehydration of Iron(II) sulfate heptahydrate hase been proposed. Based on the generalization of experimental data of hydrodynamics, the calculated dependence Euзовн=155∙Reзовн-0,55∙Hdч was obtained, which makes it possible to determine theoreticallypressure losses in the stationary layer of FeSO4·7H2O.According to the results of complex thermal analysis, the regularities of the gradual dehydration process of FeSO4·7H2O have been established in different temperature intervals. The temperature of 339K has been chosen, to implement the FeSO4∙7H2O dehydration process with the separation of the first three molecules of crystallization water, ensuring the preservation of the crystalline state of the product.The kinetics of moisture removal from FeSO4∙7H2Oat different heights of the material layer and velocities of heat agent movement have been investigated. Based on energy consumption calculations, the optimal parameters of the process were established: the height of the stationary layer Н = 60.10-3mand the fictitious velocities of the heat agent movement v0 =0,86 m/s.The filtration method of gradual dehydration of Iron(II) sulfate heptahydrate hase been proposed. Based on the generalization of experimental data of hydrodynamics, the calculated dependence Euзовн=155∙Reзовн-0,55∙Hdч was obtained, which makes it possible to determine theoreticallypressure losses in the stationary layer of FeSO4·7H2O.According to the results of complex thermal analysis, the regularities of the gradual dehydration process of FeSO4·7H2O have been established in different temperature intervals. The temperature of 339K has been chosen, to implement the FeSO4∙7H2O dehydration process with the separation of the first three molecules of crystallization water, ensuring the preservation of the crystalline state of the product.The kinetics of moisture removal from FeSO4∙7H2Oat different heights of the material layer and velocities of heat agent movement have been investigated. Based on energy consumption calculations, the optimal parameters of the process were established: the height of the stationary layer Н = 60.10-3mand the fictitious velocities of the heat agent movement v0 =0,86 m/s.

Synthesis, X-ray Structure of Two Hexa-Coordinated Ni(II) Complexes with s-Triazine Hydrazine Schiff Base Ligand

The hydrazine s-triazine ligand (E)-4,4’-(6-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)-1,3,5-triazine-2,4-diyl)dimorpholine (DMPT) was used to synthesize two new Ni(II) complexes via a self-assembly technique. The two complexes were synthesized by a one-pot synthesis strategy and characterized by elemental analysis, FTIR and single-crystal X-ray diffraction analysis to be [Ni(DMPT)(H2O)3](NO3)2.3H2O (1) and [Ni(DMPT)(H2O)3](NO3)2.H2O (2). The structures of both complexes were very similar regarding the coordination sphere and counter anions, but differ only in the number of the crystal water molecules. In the case of complex 1, there are three water molecules instead of one H2O molecule as in complex 2. In the two complexes, the DMPT ligand acts as a neutral tridentate NNN-chelate via three Ni–N coordination interactions. The coordination sphere of the Ni(II) ion is completed by three water molecules. As a result, the two complexes exhibit distorted octahedral geometry. The Hirshfeld surfaces around each entity in both complexes have been computed. Subsequently, their corresponding intermolecular interactions were quantified separately. Because the number of crystal water molecules is different in both complexes, their monomeric units are connected differently in their crystal structures where the crystal water molecules act as both hydrogen bond donor and acceptor. The polar O…H interactions are the most dominant in all entities of both complexes. As a result, strong O…H interactions are the driving force in the crystal packing of both complexes, and this is attributed to the presence of the nitrate anions and water molecules. The antimicrobial activity of the free ligand and complex 1 were determined against two selected fungal species, Gram-negative and Gram-positive bacterial strains. The free ligand was found to be inactive against all microbial species. On the other hand, the Ni(II) complex 1 was found active against the Gram-positive bacterial species Bacillus subtilis and also the Gram-negative bacterial species Escherichia coli. The respective inhibition zone diameter of the Ni(II) complex was 12 and 11 mm, respectively.

Crowding-out strategy to enhance energetics of 3-nitro-1,2,4-triazol-5-one based E-MOFs at the molecular level through adjusting pH

Based on the combination of coordination chemistry and the noncovalent interactions, the crowding-out concept is put forward to fundamentally solve the problem that the structural H2O in E-MOFs results in a decreased stability, density and heats of detonation. In this paper, “filling” the 4,4′-azobis(1,2,4-triazole) (ATRZ) molecules into the structure of NTO (3-nitro-1,2,4-triazol-5-one) E-MOFs, the coordination and crystal water molecules were successfully extruded to gain anhydrous [Cu(NTO)2(ATRZ)] (a) / [Zn(NTO)2(ATRZ)] (c) and hypohydrous [Co(NTO)2(ATRZ)(H2O)2]·ATRZ (b) by adjusting pH at room temperature and pressure, which is friendly for energetic materials. With the addition of ATRZ (high HOF) and the departure of water, the ΔfHmθ of them are becoming higher. The heat of detonation is increased by 1.33, 2.39 and 0.74 times respectively and the calculated detonation velocity of three compounds is enhanced by about 1000 m s−1 contrasted to the corresponding hydrates. The removal of water molecules did not result in a high sensitivity. More importantly, as potential catalysts for AP-based solid propellants, a and c still showed excellent catalysis for the thermal decomposition of AP (ammonium perchlorate) after modification. In this study, it took a whole new idea to radically solve the difficulties in the area of E-MOFs by a simple and original way, and this is a significant innovation for the safety of energetic material.

Structural studies on synthetic A2−x[M2(TeO3)3]·nH2O phases (A = Na, K, Rb, Cs; M = Mn, Co, Ni, Cu, Zn) with zemannite-type structures

During a systematic study on formation conditions of new compounds with zemannite-type structures, crystals of ten new oxidotellurate(IV) phases were grown under hydrothermal conditions, partially by employing a drastic reduction of the water content. The crystal structures of the obtained phases were determined by single-crystal X-ray diffraction. Na2[Ni2(TeO3)3]·2.5H2O, K2[Ni2(TeO3)3]·H2O, K2[Zn2(TeO3)3]·2H2O, Rb1.25[Co2(TeO3)3]·1.5H2O and Rb1.24[Mn2(TeO3)3]·2H2O exhibit a unit-cell with hexagonal symmetry (Z = 2, a ≈ 9.3 Å, c ≈ 7.7 Å), in which most of the other compounds with a zemannite-type structure are known to crystallize. Relative to this unit-cell, K2[Cu2(TeO3)3]·2H2O exhibits a twofold superstructure, K2[Co2(TeO3)3]·2.5H2O a twofold superstructure with an additional incommensurate modulation, Na2[Cu2(TeO3)3]·1.5H2O a threefold superstructure, and Rb1.5[Mn2(TeO3)3]·1.25H2O and Cs[Mn2(TeO3)3]·H2O a fourfold superstructure. Disorder of the alkali metal cations and crystal water molecules in the channels as well as variable water contents complicate modelling and structure refinement.

Water network chemistry to exploit the nature of catalytic water molecules in Mtb DNA gyrase: a computational study to understand the binding mechanism of fluoroquinolones

The dynamics of DNA gyrase and mutants of DNA gyrA such as G88A, A90V, S91P, D94A, D94G, D94N, D94Y; and double-point mutant (S91P-D94G), are meticulously investigated using computational approaches. Molecular dynamics (MD) and hydration thermodynamics have shed light on the fundamental, mechanistic basis of mutations on the conformational stability of Quinolone Binding Pocket (QBP) of DNA gyrase. Analysis of MD results revealed the displacement of a single crystal water molecule (HOH201) from the catalytic site of wild-type (WT) and mutants of DNA gyrA. This prompted our research group to probe the five crystal water molecules present in the QBP of the enzyme using water thermodynamics. Hydration thermodynamics analysis revealed the displacement of HOH201 due to unstable thermodynamic signatures. Further, the analysis highlighted significant changes in thermodynamic signatures and locations of five crystal water hydration sites upon mutation. Integrated MD simulations and water thermodynamics provided promising insights into the conformational changes and inaccessibility of the catalytic water molecule that can influence the design of DNA gyrase inhibitors. Communicated by Ramaswamy H. Sarma

Crystal structure of three chloridocuprate(I, II) complexes with methylene blue (MB) counterions

Abstract Three chloridocuprate complexes with methylene blue counterions of the chemical compositions [MB]+ 2[CuCl4]2− · H2O (1), [MB]+ 2[CuCl4]2− (2) and [(MB)+(CuCl2)−]3 (3) (where [MB]+ – methylthioninium cation; methylene blue cation) have been prepared by solvent-assisted mechanochemical synthesis. The reactions were carried out by mixing the copper(II) chloride dihydrate, CuCl2⋅2H2O, and methylene blue pentahydrate, [MB]+Cl− · 5H2O by grinding in an agate mortar with the addition of DMF as a solvent. The crystal structures of the compounds have been determined by single-crystal X-ray diffraction. The content of an asymmetric unit of the crystals consists of: (1) a tetrahedral [CuCl4]2− anion, two [MB]+ cations and one water molecule of crystallization; (2) a tetrahedral [CuCl4]2− anion and two [MB]+ cations; (3) trimeric [(MB)+(CuCl2)−]3 molecules with the Cu atoms coordinated by a nitrogen atom of the phenothiazine ring and two chlorine ions in a trigonal planar geometry with the copper atom in the oxidation state of +1.

Decoration of the [Nb6O19]8– cluster shell with six Cu2+-centred complexes generates the [(Cu(cyclen))6Nb6O19]4+ moiety: room temperature synthesis, crystal structure and selected properties

Abstract Mixing an aqueous solution of K8[Nb6O19]⋅16H2O with a DMSO/H2O solution of Cu(ClO4)2 · 6 H2O and cyclen at room temperature afforded crystallization of blue crystals of [(Cu(cyclen))6Nb6O19]⋅[ClO4]4·≈4H2O after slow evaporation of the solvents. The crystal structure contains the Lindqvist anion [Nb6O19]8– which is covalently expanded by six symmetry-related [Cu(cyclen)]2+ complexes via Nb-μ 2-O-Cu bridges yielding the positively charged [(Cu(cyclen))6Nb6O19]4+ cluster shell. The ClO4 − anions and crystal water molecules reside in the empty spaces of the packed clusters. The compound shows two electronic d-d transitions at energetic positions explaining the blue color.

MIXED-LIGAND GERMANIUM–LANTHANIDE COMPLEXES WITH 1-HYDROXYETHYLIDENEDIPHOSPHONIC ACID AND 2,2’-BIPYRIDINE

There were developed the novel methods for the synthesis of six mixed- metal and mixed-ligand complexes of germanium and rare earth metals (Pr, Nd, Dy, Ho, Tm, Lu) with 1-hydroxyethylidenediphosphonic acid and 2,2´-bipyridine. The compounds have been characterized using various research methods: elemental analysis, mass spectrometry, electrical conductivity, thermogravimetry, IR spectroscopy. It has proved that all complexes are crystal hydrates, belong to heterometallic mixed ligand compounds [Ln(H2O)4(bipy)2]2 [Ge(m-hedp) (m- OH)]6⸱nH2O, Ln=Pr (1); Nd (2); Dy (3); Ho (4); Tm (5); Lu (6); n = 22 (1, 2), 21 (3), 20 (4, 5), 19 (6). Their formation occurs due to the electrostatic interaction of complex cations [Ln(H2O)4(bipy)2]3+ with hexanuclear anions [Ge(m-hedp)(m- OH)]66-. According to the results of measuring the electrical conductivity of dimethylformamide solutions 1–6, it has been established that they belong to triionic electrolytes: λ (in Ohm-1∙сm2∙mol-1) for 1 = 131,3; 2 = 138,8; 3 = 145,8; 4 = 151,1; 5 = 158,3; 6 = 162,7. The cation-anionic type of complexes 1–6 has been confirmed as a result of the analysis of their mass spectrum. The analysis of the mass spectrum showed that the main decomposition direction of the complex is related to the formation of the complex cation fragment [Ln(H2O)4(bipy)2]3+, which corresponds to the most intense peak (m/z = 136, I = 55%). The thermal decomposition of compounds 1–6 includes dehydration, deaquatation, oxidative thermal destruction and the formation of final products as a mixture of Ln2O3 and GeP2O7. On the DTA curves in the interval 70–200 °C the first endothermic effect can be traced, which is accompanied by the removal of a certain number of crystallization and coordination water molecules into the gas phase. Absorption bands of the P-O bond have been detected at ~1053 and ~970 сm-1, that indicates the presence of the fully deprotonated PO32- groups in the composition of complexes. Furthermore, n(OH), ν(Ge–O), d(Ge–OH) bands characteristic for all the previously synthesized compounds with [Ge6(m-OH)6(m-hedp)6]6- anion have been detected in the IR spectra of 1–6. A set of the bands usual for the aromatic molecules n(C–C), das(CH3), ds(CH3), n(Сar=N) has been assigned with 2,2`-bipyridine in the structure of all compounds.

New iron(III) complexes with 2-formylpyridine thiosemicarbazones: Synthetic aspects, structural and spectral analyses and cytotoxicity screening against MCF-7 human cancer cells

2-Formylpyridine thiosemicarbazone - iron (III) chelates [FeL2] Cl•2H2O {L = L1 (C1) [HL1 = 4-(4-Nitrophenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide] and L = L2 (C2) [HL2 = 4-(2,5-Dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide]} were prepared. The two ligand anions in each complex resulted in saturation of the iron coordination number and consequently the existence of these complexes as 1:1 electrolytes. As well, the iron in these complexes exhibits low-spin electronic configuration. X-ray crystallography of complex C1 indicated its triclinic crystal system and P 1‾ space group. In addition, it proved the ligation through a thiol sulfur atom and two nitrogen atoms of pyridine and azomethine groups. This is while the presence of two water molecules of crystallization in the complex structure was also indicated. The ligand HL1 was selected for cytotoxicity screening against human MCF-7, A-549, HEPG-2 and HCT-116 cancer cells and the most enhanced activities were detected against the breast cells. Against these cells, the compounds HL1, HL2, C1 and C2 induced cytotoxicity, respectively, with IC50 values of 52.4, 145.4, 34.3 and 62.0 μM. However, against the healthy BHK cells, HL1 and HL2 caused cytotoxicity, respectively, with IC50 values of 54.8 and 110.6 μM and cytotoxicity with percent viabilities of 56.7 and 55.4% of the BHK cells by the complexes (137.4 μM of C1 and 131.9 μM of C2) was determined. These activities against MCF-7 cells are less significant compared with the measured value for doxorubicin. But this standard is more toxic to normal cells than the thiosemicarbazones (IC50 (doxorubicin) = 9.66 μM against MCF-7 cells and 36.42 μM against BHK cells).

New chain polymer [Yb(tpa)(H2O)2Co(CN)6]n· 7n H2O: synthesis, structure, and magnetic characteristics

The 3d– 4f heterometallic polymeric complex, namely [Yb(tpa)(H2O)2Co(CN)6]n·7n H2O [tpa = tris(2-pyridylmethyl)- amine], was synthesized and characterized. Its polymer structure is formed of [Yb(tpa)(H2O)2Co(CN)6] chains and crystallization water molecules with a two-capped trigonal prism Yb3+ coordination polyhedron; the Yb3+ coordination number is 8, and the coordination site is YbN6O2. Magnetic characteristics indicate that the complex exhibits the properties of a single-chain magnet with a magnetization reversal barrier(!E/kB) of 42 K.

Crystal structure and properties of anhydrous 5-nitroaminotetrazole

5-Nitraminotetrazole (5-NAT) is a high-energy and green explosive material that has attracted extensive attention due to its short synthesis steps and decomposition products consisting mainly of nitrogen and water. However, the presence of a crystal water molecule in the current crystal structure of 5-nitroaminotetrazole significantly affects its detonation performance and mechanical sensitivity. In this study, we report the successful synthesis of an anhydrous crystal form of 5-NAT through slow volatilization of an ethyl acetate solution under dry conditions. The anhydrous crystal form of 5-NAT exhibited increased density and detonation velocity compared to the monohydrate crystal form. Furthermore, quantum chemical analysis showed that the anhydrous crystal form exhibited increased sensitivity to external force stimulation due to stronger oxygen-oxygen and nitrogen-oxygen repulsion. In conclusion, the anhydrous crystal form of 5-NAT shows promise as a high-energy and green primary explosive.

The influence of water of crystallization in NIR-based MDMA·HCl detection

The large numbers of 3,4-methylenedioxy-N-methylamphetamine (MDMA) formulations encountered by the police and border security necessitates the need for safe, rapid and reliable tests to be performed on-site. Near-infrared (NIR) spectroscopy is a promising technique for on-scene illicit-drug detection because of its rapid analysis, non-invasive nature, broad scope to detect various substances, and small-sized sensors suitable for portable operation. The NIR spectrum of MDMA shows an intriguing, intense peak at ∼2000 nm that was found characteristic for MDMA within a large set of drugs and drug-related substances. Herein, we show that this peak can be attributed to water molecules of crystallization in the MDMA lattice. Drying experiments showed that both an anhydrous and hydrated form of MDMA·HCl exists with significantly different NIR spectra. At ambient conditions, the anhydrous form converted back to the hydrated form within 2 months. Our data analysis model was able to identify MDMA·HCl in mixtures of both forms. Assessment of seized casework materials showed that the majority of MDMA·HCl in The Netherlands is of the hydrated type. This is explained by the use of water-containing concentrated hydrochloric acid in the final conversion step of MDMA-base to the hydrochloride salt in clandestine laboratories. These findings provide insight in the challenges associated with NIR-based identification of drugs that may appear in various crystalline forms. Awareness on the existence of these forms and the consequences of library and data-model design to cope with this phenomenon will increase the robustness of on-site NIR-based drug detection.

Single crystal structure feature and quantum mechanical studies of a new binuclear Bi (III) complex and its activity against Helicobacter pylori

• ● A new compound of Bi (III) has been synthesized. • ● The title complex crystallizes in a triclinic system with space group P-1. • ● Quantum mechanical studies were performed on the complex 1. • ● Complex 1 was assessed as a drug against three standard laboratory strains of H. pylori. • ● The complex showed excellent activity against H. pylori with MIC = 8.84 μM. A new Bi (III) coordination compound formulated as [Bi 2 (µ-ox)(dipic) 2 (taa) 4 ].2H 2 O ( 1 ) where ox 2- = oxalato, dipic 2- = pyridine 2,6- dicarboxylato and taa= thiourea has been synthesized. Single-crystal X-ray diffraction (SC-XRD) analysis has been carried out to determine the structure of the complex. From SC-XRD data, it was found that complex 1 is a di-nuclear compound and the title complex crystallizes in a triclinic system with space group P-1. The coordination around of Bi (III) center is distorted pentagonal-bipyramidal. Hirshfeld surface (HS) and two-dimensional fingerprint analysis were performed to investigate the interactions between the complex and the crystallized water molecules. The results showed that the O…H bonds are decisive with a contribution portion of 35.7%. Indeed, quantum mechanical studies were performed to understand effective factors on the stability of complex 1 . Complex 1 was assessed as a drug against three standard laboratory strains (26695, B128, and 251) of Helicobacter pylori ( H. pylori ). The results showed that the complex had excellent activity against the bacterium Helicobacter pylori with MIC = 8.84 μM.

Layered Organic Conductors Based on BEDT-TTF and Ho, Dy, Tb Chlorides

Molecular semiconductors with lanthanide ions have been synthesized based on BEDT-TTF and lanthanide chlorides: (BEDT-TTF)2[HoCl2(H2O)6]Cl2(H2O)2 (1, which contains a 4f holmium cation), and (BEDT-TTF)2LnCl4(H2O)n (Ln = Dy, Tb, Ho (2–4), which contain 4f anions of lanthanides). Conductivity and EPR measurements have been carried out along with the SQUID magnetometry, and the crystal structure has been established for 1. The structure of 1 is characterized by an alternation of organic radical cation layers composed of BEDT-TTF chains and inorganic layers consisting of chains of the [HoCl2(H2O)6]+ cations interlinked by chlorine anions and crystallization water molecules. The magnetic susceptibility of 1–3 determined mainly by lanthanide ions follows the Curie–Weiss law with the Weiss temperatures of −3, −3, −2 K for 1–3, respectively, indicating weak antiferromagnetic coupling between paramagnetic lanthanide ions. The signals attributed to the BEDT-TTF+· radical cations only are observed in the EPR spectra of 1–3, which makes it possible to study their magnetic behavior. There are two types of chains in the organic layers of 1: the chains composed of neutral molecules and those formed by BEDT-TTF+· radical cations. As a result, uniform 1D antiferromagnetic coupling of spins is observed in the BEDT-TTF+· chains with estimated exchange interaction J = −10 K. The study of dynamic magnetic properties of 1–3 shows that these compounds are not SMMs.

Eliminating crystal water enables enhanced sodium storage performance in an oxalate-phosphate cathode material

The oxalate-phosphate polyanion-mixed cathode materials are promising for sodium-ion batteries (SIBs) due to their unique open-framework structures and high voltage property. However, materials of this type generally contain crystal water molecules in the lattice frameworks, which may affect their energy storage properties. This work aims to disclose the impacts of crystal water on physiochemical and electrochemical properties of Na 2 (VO) 2 (HPO 4 ) 2 (C 2 O 4 )•2H 2 O (NVPC-W). It shows that the water molecules can be eliminated by vacuum drying at 150°C. The elimination of water molecules does not change the crystal phase of the material, while the obtained Na 2 (VO) 2 (HPO 4 ) 2 (C 2 O 4 ) (NVPC) exhibits significant improvements in cycling stability, Coulombic efficiency, as well as rate performances. Kinetics analysis indicates that the existence of lattice water molecules hinders sodium-ion diffusion and promotes the degradation of electrodes. We believe the findings can help to develop high-performance cathode materials. The crystal water eliminated Na 2 (VO) 2 (HPO 4 ) 2 (C 2 O 4 ) material exhibits significant improvements in cycling stability, Coulombic efficiency, as well as rate performances. Kinetics analysis indicates that the existence of lattice water molecules hinders sodium-ion diffusion and promotes the degradation of electrodes.

Syntheses and structural characterizations of the first coordination polymers assembled from the Ni(cyclam)2+ cation and the benzene-1,3,5-tri-carboxyl-ate linker.

The asymmetric unit of catena-poly[[[(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ4 N 1,N 4,N 8,N 11)nickel(II)]-μ2-5-carb-oxy-benzene-1,3-di-carboxyl-ato-κ2 O 1:O 3] octa-hydrate], {[Ni(C9H4O6)(C10H24N4)]·8H2O} n (I), consists of a macrocyclic Ni2+ cation, a carboxyl-ate dianion and eight highly disordered water mol-ecules of crystallization. The components of the compound catena-poly[[[(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ4 N 1,N 4,N 8,N 11)nickel(II)]-μ2-5-carb-oxy-benzene-1,3-di-carboxyl-ato-κ2 O 1:O 3] monohydrate], {[Ni(C9H4O6)(C10H24N4)]·H2O} n (II), are two crystallographically unique centrosymmetric macrocyclic dications, a carboxyl-ate dianion and one water mol-ecule of crystallization. In each compound, the metal ion is coordinated in the equatorial plane by the four secondary N atoms of the macrocyclic ligand, which adopts the most energetically stable trans-III conformation, and two mutually trans O atoms of the carboxyl-ate anions in a slightly tetra-gonally distorted trans-NiN4O2 octa-hedral geometry. The crystals of both compounds are composed of parallel coordination polymeric chains running along the [010] direction in I and the [110] and [10] directions in II. The bridging carboxyl-ate anions display different modes of coordination connected with the relative orientation of coordinated O atoms, i.e., remote in I and inter-mediate in II, thus resulting in essentially different distances between the Ni atoms in the chains [11.0657 (4) and 8.9089 (2) Å in I and II, respectively]. As a result of hydrogen-bonding inter-actions, the chains are joined together in sheets oriented parallel to the (10) and (001) planes in I and II, respectively.

Solvent-Induced Cobalt(II) Cyanoguanidine Bromides: Syntheses, Crystal Structure, Optical and Magnetic Properties

Two different phase-pure cobalt(II) cyanoguanidine bromide coordination compounds, Co(C2N4H4)2(H2O)4·2Br·2H2O (1) and Co3(C2N4H4)8(H2O)8·6Br (2), were precipitated from aqueous and methanol solutions, respectively, and their structures were solved and refined from X-ray single-crystal data at 100 K. Both 1 and 2 crystallize in the triclinic system with space group P1¯. The structure of 1 consists of two crystallographically distinct isolated CoO4N2 octahedral units plus bromide anions and crystal water molecules, whereas 2 is built from both isolated octahedra and discrete binuclear cluster units made from edge-sharing octahedra. Diffuse reflectance spectra and IR analysis then go on to highlight optical and vibrational differences between these two compounds. The magnetic susceptibility of 1 is consistent with either isolated or very weakly interacting Co2+ centers whereas the magnetic susceptibility of 2 evidences the potential weak antiferromagnetic exchange interactions that may arise from superexchange within the binuclear clusters.

Crystal structures of two new divalent transition-metal salts of carb-oxy-benzene-sulfonate anions.

Hexa-aqua-nickel(II) bis-(3-carb-oxy-4-hy-droxy-benzene-sulfonate) dihydrate, [Ni(H2O)6][C6H3(CO2H)(OH)SO3]2·2H2O, (I), crystallizes in the triclinic space group P with the nickel(II) aqua complexes on centers of inversion. The carboxyl-ate group is protonated and neither it nor the sulfonate group is involved in direct coordination to the metal ions. The structure consists of alternating layers of inorganic cations and organic anions linked by O-H⋯O hydrogen bonds that also include non-coordinated water mol-ecules of crystallization. The first-row divalent transition-metal salts of this anion are reported as both dihydrates and tetra-hydrates, with two distinct structures for the dihydrates that are both layered but differ in the hydrogen-bonding pattern. Compound (I) represents the second known example of one of these structures. Hexa-aqua-cobalt(II) bis-(3-carb-oxy-benzene-sulfonate) dihydrate, [Co(H2O)6][C6H4(CO2H)SO3]2·2H2O, (II), also crystallizes in triclinic P with the cobalt(II) aqua complexes on centers of inversion. The structure is also built of alternating layers of complex cations and organic anions without direct coordination to the metal by the protonated carboxyl-ate or unprotonated sulfonate groups. A robust O-H⋯O hydrogen-bonding network involving primarily the coordin-ated and non-coordinated water mol-ecules and sulfonate groups directs the packing. This is the first reported example of a divalent transition-metal salt of the 3-carb-oxy-benzene-sulfonate anion.