Coordinated Water Molecules Research Articles

Tunable SIM properties in a family of 3D anilato-based lanthanide-MOFs.

By reacting a 3,6-ditriazolyl-2,5-dihydroxybenzoquinone (H2trz2An) anilato linker with LnIII ions (LnIII = Dy, Tb, Ho), two different series of polymorphs, formulated as [Ln2(trz2An)3(H2O)4] n ·10H2O (DyIII, 1a; TbIII, 2a, HoIII, 3a) and [Ln2(trz2An)3(H2O)4] n ·7H2O (DyIII, 1b, TbIII, 2b, HoIII, 3b) have been obtained. In these series the two DyIII-coordination networks (1a and 1b) and the TbIII-coordination polymer (2b) show a Single Ion Magnet (SIM) behavior. 1-3a MOFs show reversible structural flexibility upon removal of a coordinated water molecule from a distorted hexagonal 2D framework to a distorted 3,6-brickwall rectangular 3D structure in [Ln2(trz2An)3(H2O)2] n ·2H2O (DyIII, 1a_des; TbIII, 2a_des, HoIII, 3a_des) involving shrinkage/expansion of the hexagonal-rectangular networks. Noteworthy, 2b represents the first example of a TbIII-anilate-based coordination polymer showing SIM behaviour to date and the best SIM properties within the polymorphs. Theoretical investigation via ab initio CASSCF calculations supports this behavior, since 2b shows less mixing between the m J states of the ground state among all the studied complexes.

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Molecular models for tin dioxide nanoparticles containing 1-7 metal atoms and coordinated or constitutive water have been constructed. Dependent on the composition of the models, the coordination number of the tin atom varied from 4 to 6, and that of oxygen was 2 or 3. The considered models contained both terminal (Sn–OH) and bridging (Sn–OH–Sn) hydroxyl groups, and also bridging (Sn–O–Sn) groups. Their equilibrium spatial and electronic structures were calculated using the second-order Møller-Plesset perturbation theory method with the SBKJC valence-only basis set. To assess the gas-phase acidity of the dioxide surface, the deprotonation energy of the studied models was determined. The adsorption energy of water molecules and hydroxide ions on aprotic (incompletely coordinated) tin atoms, which act as Lewis acid centers, was calculated. In order to estimate the pKa value of the surface of tin dioxide, the Gibbs free energy was calculated for the process of formation of ion pairs due to the proton transfer from hydroxyl groups to adsorbed water molecules. Based on the analysis of the energy effects of the coordination of water molecules and of hydroxide ion, the removal of a proton and its transfer on the hydrated surface of tin dioxide, quantitative estimates have been made of the acid-base characteristics of the active sites of the SnO2 surface. The dependence of the acidity of hydroxyl groups and coordinated water molecules on the coordination number of the oxygen atom and the neighboring tin atom, as well as on the dimensions of the cluster model, was revealed. It is shown that the acidity of protonic and aprotic sites naturally decreases with an increase in the coordination number of the tin atom. The method of calculating the value of pKa used in the work for the smallest model of the SnO2×2H2O composition allows one to reproduce the experimental data for stannic acids.

A Foldable Metal–Organic Framework with cds Topology Assembled via Four-Connected Square-Planar Single Ni2+-Ion Nodes and Linear Bidentate Linkers

A binary, three-dimensional (3D), foldable, Metal–Organic Framework (MOF) of formula {[trans-Ni(H2O)2(μ-4,4′-bpy)2](ClO4)2}n (1), with CdSO4 (65 8), cds, topology, based on four-connected (4-c) square-planar single Ni2+ ion nodes and two-connected (2-c) linear rigid 4,4′-bipyridine (4,4′-bpy) ligands, was synthesized and structurally characterized via single crystal X-ray crystallography. The 41° dihedral angle between two distinct coordination environments within the 3D network of 1 produced the self-dual topology of Ni2+ nodes. Two rectangular 1D channels ran parallel to the crystallographic a-axis and b-axis, respectively, creating a 44.2% volume porosity, probed by gas (N2, CO2, and H2) sorption studies. The PXRD, FT-IR, Raman, EDS, and SEM methods were employed for the study of 1. A thermogravimetric analysis (TGA) showed that coordinated water molecules were readily removed upon heating, whereas the 3D lattice remained intact up to 370 °C.

Preparation Of Mixed Ligand Complexes Of Cerium (III) Metal Using Multidentate Ligands And Investigation Of Their Physicochemical, Spectral, Thermal, And Antibacterial Properties.

This study involves the synthesis and characterization of Cerium (III) Mixed-ligand complexes employing 2-hydroxybenzaldehyde oxime (BO) as the primary ligand and organic compounds 2-amino-3-(1H-indol-3-yl)propanoic acid (L1) , 2-amino-4-(methylthio)butanoic acid (L2) , 2-amino-3-(4-hydroxyphenyl)propanoic acid (L3) , 2-Amino-3-sulfhydrylpropanoic acid (L4) as secondary ligands. The resulting complexes exhibit a brown color and display stability, as evidenced by conductometric measurements indicating non-electrolyte behavior. FTIR analysis reveals coordination through O and N donor atoms, while thermogravimetric studies highlight stability with coordinated water molecules, supported by high decomposition temperatures. UV studies demonstrate intra-ligand and ligand-to-metal charge transfer transitions. Elemental analysis confirms a 1:2:1 ratio for the complexes. Antibacterial assays using agar cup and tube dilution methods affirm the complexes' antibacterial activity against specific bacterial strains.

Pu(VI) Oxalate Crystal Structure and Evidence of Photoreduction to Pu(IV) Oxalate.

We report the first crystal structure of a Pu(VI)-oxalate compound. This compound, [PuO2(C2O4)(H2O)]·2(H2O) (1), crystallizes in space group P21/c with a = 5.5993(3) Å, b = 16.8797(12) Å, c = 9.3886(6) Å, and β = 98.713(6)°. It is isostructural with the previously reported U(VI) compound, [UO2(C2O4)(H2O)]·2(H2O). Each plutonyl ion (PuO22+) is coordinated in the equatorial plane by two side-on bidentate oxalates, creating an infinite chain along [001]. A coordinated water molecule and twisting of the oxalates lead to a distorted pentagonal bipyramidal geometry of the Pu. A photochemical degradation was observed for 1, which resulted in the formation of a secondary crystalline phase. The absorption spectrum of this secondary phase confirmed the presence of Pu(IV), but it did not match the spectrum of Pu(C2O4)2·6H2O, which is considered to be the primary product of Pu-oxalate precipitation. While compound 1 has previously been proposed to exist in solution, this is the first time it has been isolated via crystallization. Although redox interactions between Pu and oxalate have been documented in the literature, the present study is the first observation of a photochemical reduction of Pu(VI)-oxalate. As a result, this study has expanded on the limited understanding of the Pu(VI)-oxalate system, which is important for nuclear fuel cycle applications.

Aqueous Solution Enhanced Room Temperature Phosphorescence through Coordination-Induced Structural Rigidity.

Achieving aqueous solution enhanced room temperature phosphorescence (RTP) is critical for the applications of RTP materials in solution phase, but which faces a great challenge. Herein, for the first time, a strategy of coordination-induced structural rigidity is proposed to achieve enhanced quantum efficiency of aluminum/scandium-doped phosphorescent microcubes (Al/Sc-PMCs) in aqueous solution. The Al/Sc-PMCs in a dry state exhibit a nearly invisible blue RTP. However, they emit a strong RTP emission in aqueous solution with a RTP intensity increase of up to 22.16-times, which is opposite to common solution-quenched RTP. The RTP enhancement mechanism is attributed to the abundant metal sites (Al3+ and Sc3+ ions) on the Al/Sc-PMCs surface that can tightly combine with water molecules through the strong coordination. Subsequently, these coordinated water molecules as the bridging agent can bind with surface groups by hydrogen bonding interaction, thereby rigidifying chemical groups and inhibiting their motions, resulting in the transition from the nonradiative decay to the radiative decay, which greatly enhances the RTP efficiency of the Al/Sc-PMCs. This work not only develops a coordination rigidity strategy to enhance RTP intensity in aqueous solution, but also constructs a phosphorescent probe to achieve reliable and accurate determination of analyte in complex biological matrices.

New bivalent metal chelates based on an NO-donor Schiff base ligand: synthesis, structural characterization, DFT simulation, biological evaluation, and molecular docking analysis

It is crucial to establish a correlation between the chemical structure of transition metal chelates and their anticipated biological activity to create efficient bioinorganic medications. Thus, new bivalent transition metal chelates; M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), were easily synthesized from an innovative bidentate NO-donor Schiff base ligand (HL). A comprehensive series of physicochemical techniques like FT-IR, 1H NMR, ESR, TGA and UV–Vis spectroscopy was used to characterize the synthesized compounds. The metal is evidently coupled to two ligands through the deprotonated enolic oxygen and nitrogen atoms of imine groups in all chelates. The obtained analytical and spectroscopic data revealed that the chelates of Mn(II), Co(II), Ni(II) and Cu(II) adopted octahedral structures with two coordinated water molecules. On the other hand, the Zn(II) chelate was found to be a tetrahedron, while the Cd(II) one was a distorted tetrahedron. The energy optimized geometry of HL and some of its chelates as well as their quantum reactivity descriptors were estimated by DFT analysis. The antimicrobial and cytotoxicity screening exhibited that the compounds were bioactive with various biological activities. In addition, the binding interaction characteristics of the ligand and the Cu(II), Zn(II) and Cd(II) chelates were validated by molecular docking processes using three macromolecular biological receptors (Aureolysin, Staphylococcus Aureus metalloproteinase (1BQB), a penicillin-binding protein 3 from Escherichia Coli (4PJP) and a B-DNA (1BNA). The biological findings were correlated with the calculated DFT data and molecular docking results.

Crystal structures and properties of Fe(H2O)2[Ni(CN)4]·nH2O hydrates

We report the crystal structures and properties of iron hydrate compounds. These hydrates have 2D topologies and crystallize with three different structural features depending on the number of weakly bonded water molecules. Coordinated water molecules occupy the axial sites of the iron ion and support a network of hydrogen-bonded water molecules in the interlayer region. Crystal structures of these hydrates are known for Mn, Co, and Ni but not for Fe. The structure for the solids considered herein was solved and refined from powder XRD patterns complemented by IR, UV/Vis-NIR, Mössbauer, and TG data. The relevance of this structural study is related to the application of Hofmann-like coordination polymers as spin-crossover materials when the coordinated water molecules are replaced by dipyridines, pyridine, and derivatives that form pillars between adjacent layers. Upon dehydration of these solids, a reactive material is formed by assembly of tetrahedral iron ions with square planar nickel ions.

Tailoring the solvation shells of dual metal ions for high-performance aqueous zinc ion batteries

For a long time, the issue of dendrites in neutral/mild electrolyte-based aqueous zinc-ion batteries (AZIBs) has been a matter of concern. The dendrites resulting from this problem lead to short-circuit faults and significantly reduce the cycle life, which is quite troublesome. Here, we induce uniform Zn deposition by utilizing the enhanced electrostatic shielding effect of a hybrid additive of Na2SO4 and EDTA. The limited tip-blocking effect of Na+ is due to the higher exchange reaction rate constant (kex) of water molecules in the solvation shell. The coordination of EDTA can provide a more stable solvation shell for Na+, ensuring a stronger blocking effect on Zn deposition at the tip. This enhanced electrostatic shielding effect effectively suppresses the growth of Zn dendrites. In addition, EDTA also enters the solvation shell of Zn2+ and displaces some coordinated water molecules, allowing for more reversible Zn plating/stripping without significant side reactions occurring at the Zn anode.

Photocatalytic degradation of methylene blue using sunlight-powered coordination polymers constructed from a tetracarboxylate linker

Here, we report the preparation of three coordination polymers - [Mn2(btec)]n, 1; [Ce2(H2btec)(btec)(H2O)2]n, 2; and [Fe(Hbtec)(H2O)2]n3 from 1,2,4,5-benzenetetracarboxylic acid (H4btec). Physicochemical characterization of the coordination polymers were undertaken using microanalysis, X-ray crystallography, FTIR, PXRD, TGA/DSC, and UV/visible spectrophotometry to confirm the identities of the compounds. The Mn(II) centres in 1 exhibit octahedral geometry coordinated by six oxygen atoms and crystallizes in the monoclinic space group I2/m. In 2, Ce(III) centres adopt tricapped trigonal prism geometry, coordinated by three btec4-, three from H2btec2- and the oxygen from one coordinated water molecule. It crystallizes in the triclinic space group P1¯. 3 is composed of an Hbtec ion and two water molecules coordinated to the Fe (III) ion. The band gaps of 1, 2, and 3 are 2.87, 3.10, and 3.61 eV, respectively, while their hydrogen peroxide-assisted efficiencies for the photodegradation of methylene blue are 91, 94, and 100 % respectively. An active species trapping experiment showed that an increase in hydroxy radicals (•OH) explains the enhanced efficiencies and provide an insight into the mechanism of the photodegradation of methylene blue by the photocatalysts. Efficiencies of mixtures of 2/H2O2 and 3/H2O2 reduced only slightly over five cycles of use and PXRD data revealed that 2 and 3 were chemically stable over the three cycles. Overall, the coordination polymers could serve as potential candidates for industrial-scale methylene blue degradation in the aqueous phase.

Structural, Vibrational, Thermal, and Cytotoxic Characterization of Aqua(1,10‐Phenanthroline)(L‐Serinato)Copper(II) Nitrate Complex Combined with DFT Calculations

AbstractIn this study, X‐ray diffraction confirms the crystallization of aqua(1,10‐phenanthroline)(L‐serinato)copper(II) nitrate in the triclinic system (P‐1). Density functional theory calculations are used to assign the vibration bands of Cu2+ ion and phenanthroline (phen) and L‐serine (L‐ser) ligands obtained by Raman and Fourier‐transform infrared spectroscopy. Physical and analytical properties, evaluated by computational study utilizing CrystalExplorer software, show the prevalence of H···O/O···H interaction. Thermal analyses show that the complex is stable in the temperature interval of 300–390 K. For temperatures above 390 K, the elimination of coordinated water molecules (380–430 K), mass loss of serine (440–660 K), and material decomposition process above 660 K. The solubility of the complex in water reaches 21.4 mg mL−1 at 35 °C. Parameters of drug‐likeness and assessment of absorption, distribution, metabolism, and excretion (ADME) properties are calculated. The in vitro cytotoxic assays against the cancer cell line of the HCT‐116 type (human colorectal carcinoma) exhibits toxicity (IC50 = 1.88 µm and selectivity index of 2.17) for the complex. The results highlight the potential of ternary copper complexes such as [Cu(phen)(L‐ser)(H2O)]NO3 for anticancer drug development as attractive, efficient, and low‐cost materials.

Crystal structure and photocatalytic activity of luminescent 3D-Supramolecular metal organic framework of dysprosium

A 3D supramolecular metal organic framework of dysprosium has been fabricated through a facile hydrothermal procedure with the ligand, 2,6-naphthalene disulphonic acid and the co-ligand, 4,4′-bipyridine. The MOF has been characterized as [C60H81DyN8O30S4] by routine analytical procedures. SXRD studies of the MOF show the existence of a hydrogen-bonded 3D supramolecular structure with high porosity. It crystallizes in monoclinic space group P21/n with unit cell parameters, a = 16.5424(6) Å, b = 37.0052(14) Å, c = 24.4361(9) Å, β = 100.7410°, α = γ = 90°. The Dy-MOF has eight coordinated water molecules around the metal centre and exhibits square anti-prismatic geometry. The band gap is 3.11 eV. The degradation experiments under visible light confirmed that Dy-MOF can act as a photocatalyst. Addition of hydrogen peroxide remarkably increases the degradation efficiency of the MOF through an advanced oxidation process. The newly synthesized MOF produced sharp emission peaks characteristic of dysprosium ion.

Synthesis, Structural Characterization and Photocatalytic CO2 Reduction Activity of a New Gd(III) Coordination Polymer with 6-Phenylpyridine-2-carboxylic acid and 4,4’-Bipyridine Ligands

A new Gd(III) coordination polymer, {[Gd(L1)3(H2O)2]∙L2}n (1) (HL1 = 6-phenylpyridine-2-carboxylic acid, L2 = 4,4’-bipyridine) was synthesized using 6-phenylpyridine-2-carboxylic acid, 4,4’-bipyridine, NaOH and GdCl3∙6H2O. The structure of Gd(III) coordination polymer has been characterized by IR and X-ray single crystal diffraction. The result of single crystal analysis indicates that fundamental unit of Gd(III) coordination polymer contains one Gd(III) ion, three L1 ligands, two coordinated water molecules and one uncoordinated 4,4’-bipyridine. In 1, the Gd(III) ion is eight-coordinated and surrounded by six O atoms from three L1 ligands and two O atoms from two coordinated water molecules, respectively. The complex 1 exhibits 1D chained structure by the bridging interactions of two carboxyl-oxygen atoms and O−H∙∙∙N hydrogen bonds interactions. The 1D chains are further connected by - stacking interactions to form 3D network architecture. The photocatalytic CO2 reduction activity of complex 1 has also been investigated. The complex 1 exhibits good CO2 reduction activity. With the increase of time, the yield of CO from 18.2 mmol/g in the first hour to 60.3 mmol/g in the third hour. And the CO selectivity has reached 100%. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Structurally diverse copper(II) phosphonates: Synthesis, structure, and magnetism

A dinuclear copper phosphonate [Cu2(AIPA)2(H2O)4] (1) (H2AIPA = (2-aminopropan-2-yl)phosphonic acid) was prepared, and its reaction with 4,4′-bipyridine (4,4′-bpy) and ethylenediamine (en) yielded a linear-chain polymeric complex having the composition {Cu2(AIPA)2(H2O)2(4,4′-bpy)}n (2), and an ionic complex [Cu(en)2(H2O)2][Cu(AIPA)2] (3), respectively. The complexes were thoroughly characterized, and their structures were determined by single-crystal X-ray diffraction. Complex 2 was formed by the substitution of the two coordinated water molecules in complex 1 with two 4,4′-bpy nitrogen atoms with the preservation of the cyclic dinuclear moiety and forming 1D-polymeric chains in which the {Cu2(AIPA)2} moieties are connected via the rigid 4,4′-bpy bridges. In contrast, the utilization of the chelating en ligands led to splitting the dinuclear core of 1 into the mononuclear [Cu(en)2(H2O)2]2+ cation and the [Cu(AIPA)2]2− anion forming the ionic complex (3). The temperature dependent (2.5–300 K) magnetic susceptibility at 0.1 T and field dependent magnetization measurement (in the range of 0–9 T at 2, 5, and 10 K) data are also presented and discussed, reflecting structural diversity of the complexes 1, 2, and 3, and showing the following best-fit parameters: J = –5.68(3) cm−1, gx = 1.900(1), gy = 2.098(5), gz = 2.399(1), zJ = –0.012(7) cm−1 (for 1), J1-2 = J3-4 = –0.24(4) cm−1 with giso = 2.319(4), and J2-3 = 0.2(1) cm−1 with giso = 2.319(4), and with zJ = –0.021(2) cm−1 (for 2 modelled as a polymeric alternating chain consisting of bridged dimeric units) and J = 0.185(9) cm−1, gx = 2.12(2), gy = 2.13(3), gz = 2.13(3), and zJ = –0.01(1) cm−1 (for 3).

Biocompatible, Europium-Doped Fluorapatite Nanoparticles as a Wide-Range pH Sensor.

The development of a simple, biocompatible, pH sensor with a wide range of detection, using a single fluorescent probe is highly important in the medical field for the early detection of diseases related to the pH change of tissues and body fluids. For this purpose, europium-doped fluorapatite (FAP: Eu) nanoparticles were synthesized using the coprecipitation method. Doping with the rare earth element europium (Eu) makes the non-luminescent phosphate mineral fluorapatite, luminescent. The luminous response of the sample upon dissolution in hydrochloric acid (HCl), in highly acidic to weakly basic media, makes it a potential pH sensor. A linear variation was observed with an increase in pH, in both the total intensity of emission and the R-value or the asymmetry ratio. The ratiometric pH sensing enabled by the variation in R-value makes the sensor independent of external factors. The structural, optical, and photoluminescent (PL) lifetime analysis suggests a particle size-dependent pH sensing mechanism with the changes in the coordinated water molecules around the Eu3+ ion in the nanoparticle. Given its exceptional biocompatibility and pH-dependent fluorescence intensity for a wide range of pH from 0.83 to 8.97, the probe can be used as a potential candidate for pH sensing of biological fluid.

Qualitative and quantitative contributions of intermolecular interactions, quantum chemical calculation, biological activity and visible-light driven photo catalysts studies of nickel complex of 4-amino-N-(5-methyl-1,3,4-thiadiazol-2-yl)benzenesulfonamide

This study reports the successful synthesis and characterization of a nickel complex of the sulfamethizole (smtz) ligand. The complex was characterized using 1H NMR and FT-IR spectroscopic analyses. The synthesized complex exhibited promising properties as a biological and visible light-driven photocatalyst. Under visible light radiation, it displayed remarkable photo-degradation capabilities, achieving a degradation efficiency of 91.2% within 80 min against a solution of methylene blue (MB) with a concentration of 10 PPM in 100 mL. To understand the complex's biological response, viscosity measurements were conducted to investigate its mode of binding with CT-DNA. The results demonstrated that the nickel complex exhibited stronger inhibitory activity and lower cytotoxicity compared to the smtz ligand, as evidenced by cytotoxic analysis and minimum inhibitory concentration (MIC) data against a range of gram-positive and gram-negative pathogens. Furthermore, the crystal structure of the complex was determined through single-crystal X-ray diffraction analysis, revealing its crystallization in the triclinic space group P-1. The asymmetric part of the unit cell consisted of a Ni0.5 metal atom, one -Picoline solvent molecule, one smtz ligand, and one coordinated water molecule. To gain further insights into the complex's properties, Hirshfeld surfaces (HS) and a 3D energy framework approach were utilized to visualize its active and inactive surfaces. The analysis indicated that the dispersion energy contribution in molecular packing was significantly greater than that of electrostatic energy. Additionally, calculations of the HOMO-LUMO energy and other quantum chemical parameters were performed to understand the molecule's stability. Overall, the synthesized nickel complex of the sulfamethizole ligand exhibited remarkable photocatalytic properties, strong inhibitory activity against pathogens, and a stable crystal structure. These findings contribute to the understanding of the complex's potential applications in photocatalysis and biomedical research.

Crystal structure and thermally enhanced photoluminescence in Eu(III) coordination polymers self-assembled from p-nitrobenzoic acid

Luminescent thermal quenching is a very troublesome thing for the practical application of luminescent materials, but also is a very common phenomenon. In theory, artificially reducing the number of quenching group around the luminescent lanthanide ion can effectively enhance the luminescence of lanthanide luminescent materials. In this paper, {[Eu2(NBA)6(H2O)4]∙H2O}n [Eu-NBA, NBA = p-nitrobenzoic acid] coordination polymers containing abundant coordination and interstitial water molecules were synthesized via hydrothermal methods. The chemical composition, crystal structures, and thermal stability of Eu-NBA coordination polymers were systemically investigated by Frontier-transfer infrared (FTIR) spectra, single-crystal X-ray diffraction and thermogravimetric analysis. X-ray diffraction analysis results revealed that Eu-NBA coordination polymers were crystallized into one-dimensional (1D) chain structures, where the adjacent Eu3+ ions were linked together by bidentate and/or tetradentate bridging carboxylate groups of the NBA ligands. The temperature-dependent photoluminescence spectra revealed that the shape and intensity of the luminescence spectra strongly depended on the coordination environment around Eu3+, and significant luminescent thermal enhancement was observed. These experimental results provided useful theoretical support for further understanding of the luminescence enhancement mechanism of lanthanide coordination polymers.

A 3D supramolecular framework-based electrochemical sensor for highly sensitive detection of ascorbic acid

A benzimidazole carboxylate ligand with multiple coordination sites has been designed by the aldimine condensation reaction of 2-pyridinecarboxal-dehyde and 3,4-diaminobenzoic acid, 2-(2′-pyridyl)-benzimidazole-6-carboxylic acid (H2pybimc), which solvothermally assembled with Ni2+ ions in the mixed solvents of H2O and n-propanol to generate a 3D supramolecular framework, {[Ni(Hpybimc)(NO3)(H2O)]}n (CP 1). The chemical composition and structure of CP 1 have been characterized in detail by various tools. Structural analysis demonstrates that the asymmetrical unit of CP 1 consists of one octahedral Ni2+ ion, one Hpybimc−, one NO3− and one coordinated water molecule. Adjacent Ni2+ ions are linked by Hpybimc− to form a 2D 3-connected ‘fes’-type topology, which further generates a 3D supramolecular architecture by hydrogen bonds and π···π stacking interactions. The carbon paste electrode (CPE) modified with CP 1 is fabricated (CPE 1) and applied for the electrochemical sensor of ascorbic acid (AA), which exhibits good linear correlation with AA in the concentration range of 5.0 × 10−4 to 7.3 mmol L−1 with the limit of detection (LOD) of 0.85 μmol L−1. Moreover, it has satisfactory stability, repeatability, and selectivity towards AA, which can be successfully used for the detections in real samples.

Crystal structure of calcium L-5-methyltetrahydrofolate trihydrate type I, C20H23N7O6Ca(H2O)3

The crystal structure of L-5-methyltetrahydrofolate calcium trihydrate has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Calcium levomefolate trihydrate crystallizes in space group P212121 (#19) with a = 7.1706(6), b = 6.5371(5), c = 53.8357(41) Å, V = 2523.58(26) Å3, and Z = 4. The structure is characterized by alternating hydrophobic and hydrophilic layers along the c-axis. The Ca cations are 7-coordinate, and share edges to form chains along the b-axis. Each of the water molecules acts as a donor in two hydrogen bonds. The coordinated water molecule makes two strong intermolecular O–H⋯O hydrogen bonds to carboxyl and carbonyl groups. The two zeolitic water molecules form weaker hydrogen bonds, to carbonyl O atoms, ring N atoms, and aromatic C atoms. Several N–H⋯O/N hydrogen bonds, as well as C–H⋯O hydrogen bonds, also contribute to the lattice energy.

Synthesis & Spectroscopic Studies of Chalcone Ligand Chelation with Some First Transition Metal’s

Synthesis & Spectroscopic Studies of Chalcone Ligand Chelation with Some First Transition Metal’s