Coordinated Water Research Articles

Halogenated Schiff base complexes: A new type of molecular probe for specific detection of o-Nitrophenol

o-Nitrophenol (2-NP) is common nitroaromatic (NACs) explosion-prone chemical and environmental pollutant. Due to the similarities in structure and composition of nitroaromatic compounds, it is difficult to distinguish 2-NP from other NACs by conventional probes. Hence, there is an urgent need to develop a simple and fast method for 2-NP trace detection. Herein, we report a new molecular fluorescent sensor constructed from the halogenated Schiff base complex [Zn(3Br5Cl-salpn)(H2O)2] (Zn-χ-L). Identifiability analysis revealed that Zn-χ-L can be used as a highly selective and sensitive molecular sensor for 2-NP, and the fluorescence signal can rapidly identify 2-NP and distinguish 2-NP from other nitroaromatics at a detection limit of (LOD) of 2.20 μM with a response speed of less than 15 s. Unexpectedly, compared with conventional NACs probes, the fluorescence signal of Zn-χ-L is not affected by solvents, which intensity remained essentially constant in the solvents of different polarities. Based on the experimental data, the potential roles of the halogenated ligands, as well as the coordination water molecules in improving the sensitivity and specificity are discussed in detail.

Selective Uptake of Ethane/Ethylene Mixtures by UTSA-280 is Driven by Reversibly Coordinated Water Defects

The metal–organic framework (MOF) UTSA-280 has been shown previously to separate ethane/ethylene mixtures. We show that this separation is kinetic; if full equilibrium is reached, the MOF is not selective. The time scales associated with this kinetic separation are sufficient to make the material potentially interesting for practical separations. The observation of kinetic separation is surprising because the MOF’s one-dimensional (1D) channels are small enough that molecular motion along the channels would be expected to take place by single-file diffusion, which is not observed. We show using a combination of experimental and modeling techniques that diffusion of molecules between adjacent 1D channels through local defects associated with coordinated water molecules allows net mixing of molecules and, moreover, that this process is potentially responsible for the selective nature of the observed kinetic separation. We show how activation and regeneration conditions play an essential role in controlling the density of these local defects.

Comparative transcriptome analysis of grafting to improve chilling tolerance of cucumber.

Grafting with pumpkin as rootstock could improve chilling tolerance of cucumber; however, the underlying mechanism of grafting-induced chilling tolerance remains unclear. Here, we analyzed the difference of physiological and transcriptional level between own-rooted (Cs/Cs) and hetero-grafted (Cs/Cm) cucumber seedlings under chilling stress. The results showed that grafting with pumpkin significantly alleviated the chilling injury as evidenced by slightly symptoms, lower contents of electrolyte leakage (EL), malondialdehyde (MDA), hydrogen peroxide (H2O2), and superoxide anion (O2-) and higher relative water content in Cs/Cm seedlings compared with Cs/Cs seedlings under chilling stress. RNA-seq data showed that grafting induced more DGEs at 8 °C/5 °C compared with 25 °C/18 °C. In accordance with the increase of the activities of antioxidant enzymes (SOD, POD, CAT, APX), grafting upregulated the expression of the regulated redox-related genes such as GST, SOD, and APX. Moreover, grafting increased the expression of genes participated in central carbon metabolism to promote the conversion and decomposition of sugar, which provided more energy for the growth of Cs/Cm seedlings under chilling stress. In addition, grafting regulated the genes involved in the intracellular signal transduction pathways such as calcium signal (CAML, CML, and CDPK) and inositol phospholipid signal (PLC), as well as changed the gene expression of plant hormone signal transduction pathways (ARF, GAI, ABF, and PYR/PYL). These results provide a physiological and transcriptional basis for the molecular mechanism of grafting-induced chilling tolerance of cucumber seedlings.

Boosting temperature sensing capacity within isoreticular zinc(II) metal-organic frameworks luminescent thermometers

Developing a convenient and accurate temperature detection method is of great importance in industrial production, biochemical processes and scientific research. As a noncontact optical temperature sensing technique, luminescence thermometry has been attracted increasing interest. Here we present two Zn(II) metal-organic frameworks (MOFs) with the formulas of {(H3O)[Zn2(btca)2(taz-NH2)x(taz-CH3)1-x]·H2O}n (x ​= ​1 (1); x ​= ​0 (2)) (H2btca ​= ​benzotriazole-5-carboxylic acid, Htaz-NH2 ​= ​5-amino-1H-tetrazole and Htaz-CH3 ​= ​5-methyl-1H-tetrazole) by virtue of the mixed-ligand approach for photoluminescence sensors as luminescence thermometries over tunable temperature range. Two MOFs exhibit 1D hexagonal nano-channels along the [100] direction, occupied by lattice water molecules. The temperature dependent photoluminescent characteristic of 1 and 2 reveal that the luminescence signals can be decreased as temperature rises from 120 to 400 ​K, thereby achieving the non-destructive temperature detection. Furthermore, linear correlations are presented between the luminescence intensities and the low temperatures for 1 and 2. Satisfying relative sensitivities of 0.49% K−1 for 1 and 0.61% K−1 for 2, and small temperature uncertainties of 0.062 ​K for 1 and 0.049 ​K for 2 ​at 400 ​K could be acheieved. Notably, the intensity-based luminescent thermometer measurements reveal that 2 shows extremely more linear with temperature and wider temperature range than those of 1, indicating that 2 is a more considerable luminescence thermometry over tunable temperature range.

Synthesis, structure, and catalytic activity of polyoxometalate (C7H15N4)2[Co(H2O)6][C6H12N2CoMo6O24]·4H2O in the azide–alkyne cycloaddition reaction

A new polyoxomolybdate with a formula of (C7H15N4)2 [Co(H2O)6] [C6H12N2CoMo6O24]·4H2O (1) was synthesized and then it was characterized using IR, EDX and X-ray crystallography. The unit cell of 1 consists of two [Co(H2O)6]2+ and one N-methyluroptropine (C7H15N4)+ cations, and one polyanion [C6H12N2CoMo6O24]4- and four lattice water molecules. In the polyanion [C6H12N2CoMo6O24]4-, molybdenum metals are surrounded by two terminal and one bridging oxygen atoms and also one oxygen of the trimethanolamine ligand is coordinated to each Mo metal. Cobalt metal in the center of the polyanion is also bonded to four bridged oxygen atoms and two oxygen atoms of the trimethanolamine ligand. This novel polyoxomolybdate was used as an efficient catalyst for the azide–alkyne cycloaddition reaction to produce various 1,2,3-triazoles in high yields (34–99%).

Stricter energy regulations and water consumption: Firm-level evidence from China

Coordinating water and energy saving contributes to the sustainable development of China's industrial sector and alleviates the resource shortage risk. Taking the mandatory energy-saving targets outlined in the “11th Five Year Plan” as a quasi-natural experiment, in this study, the difference-in-differences strategy is employed to examine the real impact of stricter energy regulations on water consumption intensity. The results show that after strictly restricting energy input, the water consumption intensity of industrial enterprises has increased significantly. This result is reliable according to several robustness checks. The increased water consumption intensity caused by stricter energy regulations is particularly apparent in regions with high energy-saving targets, non-state-owned enterprises, large-scale enterprises, and high-energy consuming sub-sectors. The imposition of stricter energy regulations has not changed the input preference and substitution relationship between water and energy; therefore, it does not significantly impact the total water consumption of enterprises. However, the decline of energy input leads to an imbalanced factor input structure, which reduces the technical efficiency and output level. The total water input scale of enterprises has not been adjusted synchronously with the decreasing output level, resulting in an increase of consumed water per unit output.

Chitosan-based composite films to remove cationic and anionic dyes simultaneously from aqueous solutions: Modeling and optimization using RSM

Regarding the existence of cationic and anionic dyes in the water environment developing new and effective techniques to remove them simultaneously is essential. Herein, a chitosan/poly-2-aminothiazole composite film reinforced with multi-walled carbon nanotube-Mg Al-layered double hydroxide (CPML) was created, characterized, and used as an effective adsorbent for methylene blue (MB) and methyl orange (MO) dyes removal from the aquatic medium. The SEM, TGA, FTIR, XRD, and BET methods were used to characterize the synthesized CPML. Response surface methodology (RSM) was utilized to evaluate dye removal based on the initial concentration, dosage, and pH factors. The highest adsorption capacities were measured at 471.12 and 230.87 mg g−1 for MB and MO, respectively. The study of different isotherm and kinetic models revealed that the adsorption of the dyes onto CPML nanocomposite (NC) was correlated with the Langmuir and pseudo-second-order kinetic model, which indicated a monolayer adsorption manner on the homogeneous surface of NCs. The reusability experiment clarified that the CPML NC could be applied multiple times. Experimental results show that the CPML NC has sufficient potential for treating cationic and anionic dye-contaminated water.

Discovery and Isolation of Two Arsenotungastate Species: [As4W48O168]36– and [As2W21O77(H2O)3]22–

Two novel arsenotungstate species, [As4W48O168]36- (1a) and [As2W21O77(H2O)3]22- (2a), have been successfully isolated under a one-pot synthetic method. 1a is the second largest arsenotungstate cluster and is constructed from four {AsW12} clusters combined together. 2a can be described as lacunary sites of {As2W19} filled by {W2O8} units. Compounds 1 and 2 exhibit proton conductivity properties, and the conductivity value of 1 is 5.0 × 10-3 S cm-1 at 98% relative humidity and 75 °C. This work proves that the lattice water molecules and polyoxoanions can participate in the formation of a hydrogen bond, acting as effective pathway for intermolecular proton conduction.

Synthesis, Structure, and Luminescence of a Molecular Europium Tetracyanoplatinate Incorporating 4,5-Diazafluoren-9-One

Eu2(Pt(CN)4)3(H2O)12]·4C11H6N2O·6H2O represents a new member to the lanthanide tetracyanoplatinate family of materials. The synthesis, single-crystal X-ray structure, and photoluminescence properties of this compound are reported herein. The compound contains dimeric [Eu2(Pt(CN)4)3(H2O)12] molecules in which the Eu3+ sites are connected with trans-bridging [Pt(CN)4] 2− anions and co-crystallized along with 4,5-diazafluoren-9-one (dafone) and lattice water. Prominent noncovalent interactions that stabilize the structure include H-bonding as well as short stacking interactions involving the planar tetracyanoplatinate anions in conjunction with the planar dafone molecules. Photoluminescence measurements illustrate that Eu2(Pt(CN)4)3(H2O)12]·4C11H6N2O·6H2O contains multiple emitting states and also displays enhanced Eu3+-based emission due to energy transfer within the compound.

A luminescent heterometallic Tb–Al ion-pair complex with a cubic (H2O)8-octamer

A heteronuclear Tb-Al complex (1) was obtained by pyridine-2,6-dicarboxylic acid (H2PDA), AlCl3 and Tb4O7 under hydrothermal condition. Single-crystal X-ray diffraction analysis reveals that 1 is an ion-pair and consists of [Al(H2O)6]3+ cation and [Tb(PDA)3]3- anion; the [Al(H2O)6]3+ cations and [Tb(PDA)3]3- anions are further connected by hydrogen bonds to construct a 3D NaCl-like topology. Lattice water molecules in 1 fabricate a cubic (H2O)8-octamer by hydrogen bonds, which is located in the void of 1. Luminescent property indicates efficient energy transfer from PDA3- ligand to Tb3+ in 1, exhibiting the typical green emission of Tb3+ in the visible region.

Shape memory luminescent cellulose/chitosan hydrogel for high sensitive detection of formaldehyde

Hybrid hydrogels containing biomacromolecules have been widely used in sensors, fluorescent probes, and other fields due to their high biocompatibility and nontoxicity. In this paper, tough hydrogels with interconnected macro-pores have been fabricated by freeze-induced chemical cross-linking of microfibrillated cellulose (MFC) and organic modified chitosan (CS). In this hydrogel materials, three-dimensional networks were formed by abundant hydrogen bonds and chemical cross-linking. Luminescent lanthanide complexes were covalently bonded to the hydrogel networks through coordination of Eu3+ ions with 2, 3-pyridine dicarboxylic acid modified chitosan. The luminescence of hydrogel materials was further improved by the replacement of coordination water with 2-thiophenyltrifluoroacetone (TTA). The prepared hydrogels showed excellent shape memory properties both under water and in air. The stress of the hybrid hydrogel at 80 % strain can reach 159 kPa, which is much higher than that of the traditional microfibrillated cellulose-based hydrogels. The obtained luminescent hybrid hydrogels exhibited an excellent fluorescence detection effect on formaldehyde. The detection limit for formaldehyde is 45.7 ppb, which is much lower than the WHO standard (80 ppb for indoor air). The novel, facile preparing procedure may extend the potential applications of hybrid lanthanide luminescent hydrogel as fluorescence probes for pollution monitoring, especially for formaldehyde and other organic aldehydes.

Cationic Polystyrene-Based Hydrogels as Efficient Adsorbents to Remove Methyl Orange and Fluorescein Dye Pollutants from Industrial Wastewater.

Water pollution from dyes is harmful to the environment, plants, animals, and humans and is one of the most widespread problems afflicting people throughout the world. Adsorption is a widely used method to remove contaminants derived from the textile industry, food colorants, printing, and cosmetic manufacturing from water. Here, aiming to develop new low-cost and up-scalable adsorbent materials for anionic dye remediation and water decontamination by electrostatic interactions, two cationic resins (R1 and R2) were prepared. In particular, they were obtained by copolymerizing 4-ammonium methyl and ethyl styrene monomers (M1 and M2) with dimethylacrylamide (DMAA), using N-(2-acryloylamino-ethyl)-acrylamide (AAEA) as cross-linker. Once characterized by several analytical techniques, upon their dispersion in an excess of water, R1 and R2 provided the R1- and R2-based hydrogels (namely R1HG and R2HG) with equilibrium degrees of swelling (EDS) of 900% and 1000% and equilibrium water contents (EWC) of 90 and 91%, respectively. By applying Cross' rheology equation to the data of R1HG and R2HG's viscosity vs. shear rate, it was established that both hydrogels are shear thinning fluids with pseudoplastic/Bingham plastic behavior depending on share rate. The equivalents of -NH3+ groups, essential for the electrostatic-based absorbent activity, were estimated by the method of Gaur and Gupta on R1 and R2 and by potentiometric titrations on R1HG and R2HG. In absorption experiments in bulk, R1HG and R2HG showed high removal efficiency (97-100%) towards methyl orange (MO) azo dye, fluorescein (F), and their mixture (MOF). Using F or MO solutions (pH = 7.5, room temperature), the maximum absorption was 47.8 mg/g in 90' (F) and 47.7 mg/g in 120' (MO) for R1, while that of R2 was 49.0 mg/g in 20' (F) and 48.5 mg/g in 30' (MO). Additionally, R1HG and R2HG-based columns, mimicking decontamination systems by filtration, were capable of removing MO, F, and MOF from water with a 100% removal efficiency, in different conditions of use. R1HG and R2HG represent low-cost and up-scalable column packing materials that are promising for application in industrial wastewater treatment.

Copper(II) and zinc(II) complexes bridged by benzenoid aromatic oxocarbon and dicarboxylate dianions

A novel series of Cu(II) and Zn(II) complexes were constructed through the bridging croconate (C5O5)2−, squarate (C4O4)2− and 2,5-pyridine-dicarboxylate (Py2,5-dc)2− dianions. These include pent- [Cu5(epdmpy)4(C5O5)2(H2O)6](ClO4)6‧12H2O (1) and tri-nuclear [Cu3(bepza)2(Py2,5-dc)2(ClO4)2(H2O)2]‧2H2O (4), dinuclear [Zn2(MeDPA)2(C4O4)(H2O)4](ClO4)2 (7), and 1-D- coordination polymers (CPs) catena-{[Cu2(bpzpy)2(C5O5)](ClO4)2‧MeOH} (2) and catena-{[Zn(4,4′-bipy)(H2O)4](C5O5)(H2O)} (6) as well as the mononuclear [Cu(HBph2,2′-dc)(pmdien)]ClO4 (5) have been synthesized and spectroscopically characterized as well as by single crystal X-ray crystallography. The reaction of aqueous solution Cu(ClO4)2, pymeea and C5O52− resulted in the unprecedently bis(oxalato) [Cu2(Pymeea)2(C2O4)(ClO4)2(H2O)2] (3). In these complexes, (C5O5)2−, squarate (C4O4)2− and (Py2,5-dc)2− ligands display a variety of coordination bonding modes. In complexes 1 and 2 the croconato is binding as 1,2-bidentate-3-monodentate but in addition 5-mono-dentate semi-coordinate bonding was detected for 2, whereas in 6 as counter dianion. The bonding mode in the squarato 7 was achieved through the trans μ1,3-mono-dentate. In the di-carboxylato compounds, only five-membered chelate ring was formed in 5via one of the carboxylate groups, whereas in 4 bridging was conducted through a mono-carboxylate and five-membered chelate ring including the second carboxylate and pyridyl nitrogen. In complexes 1–5 and 7, hydrogen bonds of type OH⋯O and/or NH⋯O are connecting the complex cations with the perchlorate anions/ligands to generate different dimensional supramolecular network structures, whereas in 6, the 3D network was formed through hydrogen bonding between the coordinated aqua and lattice water molecules. Non-covalent ring⋯ring interactions were also observed between pyridyl rings in complexes 1, 6 and 7, and between pyrazolyl rings as well as pyridyl ring in 2.

Proton Conductive Mononuclear Hydrogen-Bonded Cobalt(II) Spin Crossover Complex

The development of molecule-based switchable multifunctional materials remains an important challenge in molecular science. In particular, achieving high proton conductivities in spin crossover (SCO) compounds is of significant interest as the spin state can be controlled via proton transfer induced by an electric field, which leads to magnetoelectric effects and molecular spintronics. However, to the best of our knowledge, no studies have reported on proton-conductive SCO complexes. Thus, herein, we demonstrated the high proton conductivity of a mononuclear hydrogen-bonded Co(II) SCO compound, [Co(COOH-terpy)2](ClO4)2·4H2O (1·4H2O; COOH-terpy = 4′-carboxyl-2,2′:6′,2″-terpyridine). The [Co(COOH-terpy)2] 2+ cation assembled in the solid state via hydrogen-bonding between lattice water molecules and formed a 1D hydrogen-bonded chain. Each 1D chain was linked via CH−π interactions and C–C interactions and produced a complicated 3D supramolecular framework. Magnetic susceptibility and alternative current impedance measurements for 1·4H2O revealed incomplete spin transition behaviors and high-proton-conduction behaviors in identical temperature regions. 1·4H2O exhibited a proton conductivity of 1.68 × 10–3 S cm–1 at 353 K and 98% relative humidity. Notably, this is the first example of a proton-conductive mononuclear SCO compound having the hydrogen-bonding networks. Thus, the results of this study can be used to develop new design guidelines for molecular proton conductors, further leading to the development of multifunctional molecular switching materials.

Synthesis, structural, spectroscopic and magnetic studies of tetranuclear Ni(II) and Co(II) clusters based on cyclobutyl and cyclopentyl-substituted analogues of zoledronic acid

Three discrete tetranuclear coordination compounds with formulae (H3O)+[M4(HL)3(H2O)6]–·xH2O where M = Ni(II), HL = HcbtZol3– (1a), M = Ni(II)/Co(II), HL = HcptZol3– (2a/2b) and x = 13.8, 16.8 or 10.5 for 1a, 2a and 2b, respectively, (H4cbtZol = 1-hydroxy-2-[1-(1H-imidazol-1-yl)cyclobutyl]ethylidene-1,1-diphosphonic acid, H4cptZol = 1-hydroxy-2-[1-(1H-imidazol-1-yl)cyclopentyl]ethylidene-1,1-diphosphonic acid) were hydrothermally prepared and characterized by single crystal X-ray diffraction, IR, UV-Vis-NIR, thermal analysis and magnetic studies. All the compounds crystallize in the trigonal R3¯ space group and show a propeller-shaped {M1IIM2II3O6} cores with M cations arranged into trigonal pyramid, in which the M1 ion is located in the apex while three peripheral M2 ions occupy the vertices of a triangle base. Both M1 and M2 are six-coordinate with M1 coordination octahedron slightly contracted along the 3-fold axis towards trigonal antiprism and peripheral M2 octahedrons slightly rotated towards trigonal prism. Discrete [M4(HL)3(H2O)6]– coordination units are assembled by O–H···O interactions involving hydroxyl O atom and coordinated water molecules as proton donors. Multiple lattice water molecules additionally stabilize the crystal structure through O–H···O interactions.All the compounds reveal thermal stability up to ca. 90 °C above which lattice water starts to be released. The architecture of [M4(HL)3(H2O)6]– cores remains intact up to ca. 130–140 °C.Qualitative analysis of potential paths of magnetic interactions in tetranuclear cores suggests ferromagnetic exchange with antiferromagnetic admixture.

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.

Synthesis, crystal structure and antibacterial activity of zinc(II) complexes with Schiff bases derived from 5-fluorosalicylaldehyde

By a condensation of aliphatic amine containing adamantyl groups (amantadine, memantine, or 3-amino-1-adamantanol) and 5-fluorosalicylaldehyde, three new Schiff base ligands, HL1 – 3 , were synthesized. One Schiff base, zinc(II) chloride, and NaOH were stirred in anhydrous methanol generating three new zinc(II) complexes, C34H38F2N2O2Zn (1), C38H46F2N2O2Zn (2), and C34H38F2N2O4Zn (3), respectively. These complexes were characterized by melting point, elemental analysis, infrared spectrum, ultraviolet–visible spectrum, 1H NMR analysis, thermal analysis, and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis shows that 1 and 3 crystallize in the monoclinic system with space group P2 1 /c, but 2 crystallizes in the orthorhombic system with space group Pbca. Each asymmetric unit in 1 is composed of one zinc(II) and two deprotonated ligands; each asymmetric unit in 2 is constituted of one zinc(II), two deprotonated ligands as well as one dichloromethane. Each asymmetric unit in 3 is made up of one zinc(II), two deprotonated ligands, one methanol, and one lattice water. The central zinc(II) in 1–3 is four-coordinate via two nitrogen atoms and two oxygen atoms from the corresponding Schiff base ligands, forming a distorted tetrahedral geometry. The antibacterial activities of the three Schiff base ligands and the corresponding complexes against two gram positive bacteria, Staphylococcus aureus and Bacillus subtilis, and a gram negative bacteria, Escherichia coli, were tested.

Pyridyl-imidazole copper compounds

Three 4-(2’-pyridyl)imidazole (4-pyim) complexes of copper(II) have been synthesized and studied structurally and magnetically. The structures of [CuCl2(4-pyim)] (1), [CuCl(4-pyim)2]2Cl2(H2O)10 (2), and [Cu(CuCl4)(4-pyim)2][Cu(H2O)(4-pyim)2](CuCl4)(H2O)4 (3) are reported. Single-crystal X-ray diffraction measurements show that 1 crystallizes in the monoclinic space group P21/n with a four-coordinate Cu(II) ion forming dimers via semi-coordinate bonds to bridging chloride ions. The structure of 1 shows the copper and chloride ions disordered over two sites. Compound 2 crystallizes in the triclinic space group P – 1 with five-coordinate Cu(II) ions in a highly distorted geometry between square pyramidal and trigonal bipyramidal. It has an extensive hydrogen bonding network created by 10 lattice water molecules, chloride ions, and nitrogen atoms in the ligands. Compound 3 crystallizes in the monoclinic space group Cc with both four- and five-coordinate Cu(II) ions present in the lattice; the five-coordinate Cu(II) ions display highly distorted geometries. All three compounds have hydrogen bonding and π-stacking interactions among the 4-pyim rings. Magnetic susceptibility data were collected on 1. Magnetic susceptibility data of 1 shows that it exhibits modest antiferromagnetic interactions which are best fit using a honeycomb model [(2J = −2.6(2) K), 2J’ = −1.6(2) K, ]. Disorder in the crystal structure decreases the rate of growth of the correlation length at low temperatures, lowering the temperature of the expected maximum in χ below the range of the data.

Synthesis, characterization and crystal structure of a dodeca-nuclear cobalt (II)cube-octahedron

<p>The new cobalt (II) complex, [Co<sub>12 </sub>(cpip)<sub>12</sub>(H<sub>2</sub>O)<sub>12</sub>].18.56H<sub>2</sub>O where H<sub>2</sub>cpip = 2-(carboxy-phenyl) amino-propanoic acid, was isolated as pink-like prism crystals from the reaction of Co(NO<sub>3</sub>)<sub>2</sub>.6H<sub>2</sub>O and H<sub>2</sub>cpip in an ethanolic solution. The complex was characterized by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray single-crystal diffraction. The symmetric unit of the title complex contains twelve cobalt atoms arranged in a cube-octahedron. Each divalent cation of cobalt is iso-octahedrally coordinated to four oxygen atoms of two cpip2- ligands in the equatorial plane. The axial plane is occupied by an amino nitrogen atom of one of the cpip2- ligands and an oxygen atom of a water molecule. The lattice water molecule in the metallocycle cavity involved OH­­­O hydrogen bonding with the coordinated water molecules.</p>

Impact of Post-Synthesis heat treatment avoidance on cobalt carbonate hydroxide as a Battery-Type electrode material

In this study, the electrochemical energy storage properties of one-dimensional (1D) hierarchical nanowire array (NWA) of cobalt carbonate hydroxide hydrate (Co6(CO3)2(OH)8·H2O) (CCH) is explored. The 1D nanostructure is advantageous due to their better charge/ion transport properties. The material was synthesized via. simple, and facile hydrothermal approach. The highlighting feature of this work lies in its post-synthesis process, where the authors deliberately avoided the post-synthesis heat treatment process to utilize the hydrated (x‧H2O) part associated with the lattice water which eventually led CCH in a unique robust crystal structure. Here, the authors have explored multifaceted aspects of 1D CCH NWAs, including the nanowire synthesis, their growth mechanism, and pseudocapacitive charge storage properties. The authors propose a novel charge storage mechanism, insertion pseudocapacitance, which depends on the (de)intercalation of cations (e.g., Li+, Na+, K+, and H+), where tunnels play a significant role in charge storage properties. In this type of charge-storage mechanism, cationic diffusion occur from the interior of the crystalline framework along with the surface-confined phenomena. The electrochemical energy storage performance in terms of specific capacity (Csp) is found to be 243.55 mAhg−1 @ 5 mVs−1 scan rate and 161.465 mAhg−1 at 2500 mAg−1 current density. The material exhibited excellent capacity retention of ∼ 95 % and ∼ 86 % at significantly higher current densities of 20,000 mAg−1 and 100,000 mAg−1, respectively. This work tries to establish the structure-electrochemical property correlation of the CCH which has an exceptional crystal structure that is deduced ∼ 20 years after its first report. Therefore, the authors emphasize exploring the fundamental understanding of the CCH from the crystallographic point of view and its relevance to electrochemical energy storage. This work will help in exploring the next-generation metal carbonate hydroxide hydrate-based (MCH) materials.