Uncoordinated Water Mol-ecules Research Articles

Synthesis and Crystal Structure Studies of a New Complex of Co (III)-Schiff Base Derivative Derived from Isonicotinohydrazide

A new Co(III) complex prepared by the reaction of N'–(1–(pyridin–2 yl)ethylidene) isonicotinohydrazide (H2L) with Co(II) ion is reported in this paper. The H2L ligand is structurally characterized by elemental analysis, NMR, and infrared spectroscopies. The mononuclear complex [Co(HL)2]·Cl·3H2O (1), is characterized by infrared spectroscopy, elemental analysis, conductance, magnetic room temperature measurement and single X-ray diffraction. The complex crystallizes in the monoclinic system with space group P21/c. The parameters of the unit cell are a = 9.6818(3) Å; b = 25.1587(6) Å; c = 11.5481(3) Å; β = 101.797(3) °; Z = 4; Rint = 0.0313 and wR(F2) = 0.0812. The asymmetric unit of the compound contains a discrete [Co(HL)2]+ cation one free chloride anion and three uncoordinated water molecules. In the discrete cation one Co3+ ion two organic ligand molecules are present. The coordination polyhedron around the Co3+ center is best described as a distorted octahedral with CoN4O2 chromophore. The crystal structure of the complex is stabilized by intramolecular and intermolecular hydrogen bonds.

Cu(II) complexes of 5-sulfamoylbenzoic acid derivatives: Synthesis and characterization

Novel three Cu(II) complexes {[Cu2(MeOsba)4(H2O)2] (1, HMeOsba = 2-methoxy-5-sulfamoylbenzoic acid), [Cu(MeOsba)2(2a5mp)2].3H2O (2, 2a5mp = 2-amino-5-methylpyridine) and [Cu(Clsba)2(2amp)2].2H2O (3, 2amp = 2-picolylamine, HClsba = 2,4-dichloro-5-sulfamoylbenzoic acid)} were synthesized. The structure of 1–3 characterized by FT-IR, AAS, X-ray crystallographic analysis, UV, molar conductivity and magnetic moment. All complexes (1–3) formed crystals in the P-1 space group and the triclinic crystal system. The symmetric units of complexes (1–3) contains two Cu(II) cations, four MeOsba anions as bridges and two aqua ligands for 1, one Cu(II) cations, two MeOsba anions, two 2a5mp and three uncoordinated water molecules for 2 and one Cu(II) cations, two Clsba anions, two 2amp and three uncoordinated water molecules for 3. The structure of 1–3 have a crystallographic inversion centre.

Supramolecular architecture of sodium heterocyclic dithiocarbamate salt: Insights from spectral analysis and bond valence sum characterization

The hydrated sodium salt of 1,2,3,4-tetrahydroquinolinedithiocarbamate (1) has been successfully synthesized and characterized using IR, NMR, and X-ray single crystal analysis. The υC–S and thioureide υC–N bands appeared at 1484 cm−1 and 968 cm−1, respectively, in Na(H2O)3+(thqdtc)– • H2O. The notable NCS2 carbon signal emerged at 212 ppm, credited to unique nitrogen and sulfur-induced deshielding effects. Compound 1 crystallizes in the monoclinic system, P21/c space group, with dimensions a = 14.4297(4) Å, b = 6.1534(2) Å, c = 17.6701(4) Å, β = 108.7340(10)°, V = 1485.83(7) Å3, and Z = 4. The structure of 1 exhibits a supramolecular architecture through secondary interactions, such as weak intermolecular interactions that link the molecules into a linear polymeric chain. The incorporation of heterocyclic rings in the dithiocarbamate ligands leads to the formation of an intriguing supramolecular architecture, as confirmed by BVS analysis results. The BVS value of sodium does not agree well with the formal oxidation state due to the interactions of anions, cations, coordinated and uncoordinated water molecules.

Modulation of single-chain magnet behaviour in a heterometallic Fe2Co cyanide-bridged 2D sheet.

A cyanide-bridged Fe2Co 2D sheet exhibiting electron transfer coupled spin transition (ETCST) with co-existence of magnetic ordering below 50 K is reported. The complex exhibits single-chain magnet behaviour where the uncoordinated water molecules act as an exchange-breaking impurity by allowing only a fraction of the molecule to undergo a spin state change. The paramagnetic centres prevail throughout the chain on desolvation, thereby increasing the number of correlated units in the chain.

Synthesis, crystal structure and Hirshfeld surface analysis of di-acetato-bis-[4-(2-amino-eth-yl)morpholine]cadmium tetra-hydrate.

The title coordination compound, [Cd(C2H3O2)2(C6H14N2O)2]·4H2O, was synthesized by mixing 2 moles of 4-(2-amino-eth-yl)morpholine and 1 mole of cadmium acetate in double-distilled water. The Cd atom is octa-hedrally coord-inated by two N,N'-bidentate ligands [4-(2-amino-eth-yl)morpholine] and two trans-located acetate mol-ecules. The Cd atom is located on a center of inversion, whereas the 4-(2-amino-eth-yl)morpholine and four water mol-ecules are adjacent to the acetate mol-ecules. The chair conformation of the morpholine mol-ecules is confirmed. In the crystal, adjacent metal complexes and uncoord-inated water mol-ecules are linked via N-H⋯O and O-H⋯O hydrogen-bonding inter-actions, generating R 2 2(6), R 6 6(16), R 6 6(20) and S 1 1(6) motifs and forming a three-dimensional network. A Hirshfeld surface analysis indicated the contributions of various contacts: H⋯H (71.8%), O⋯H/H⋯O (27.1%), and C⋯H/H⋯C (1.0%).

Structure Guiding Supramolecular Assemblies in Metal-Organic Multi-Component Compounds of Mn(II): Experimental and Theoretical Studies

Two multi-component coordination compounds of Mn(II), viz. [Mn(H2O)6](2-Mepy)2(4-NO2bz)2·2H2O (1) and [Mn(H2O)6][Mn(2,3-PDCH)3]2 (2) (where, 2-Mepy = 2-methylpyridine, 4-NO2bz = 4-nitrobenzoate, 2,3-PDC = 2,3-pyridinedicarboxylate), have been synthesized and characterized using elemental, spectroscopic (FT-IR and electronic), TGA and single-crystal X-ray diffraction analyses. Complex 1 is a co-crystal hydrate of Mn(II) involving uncoordinated 2-Mepy, 4-NO2bz and water molecules; while compound 2 is a multi-component molecular complex salt of Mn(II) comprising cationic [Mn(H2O)6]2+ and anionic [Mn(2,3-PDCH)3]−complex moieties. The uncoordinated 2-Mepy and 4-NO2bz moieties of 1 are involved in lone-pair (l.p)-π and C–H⋯π interactions which stabilize the layered assembly of the compound. The crystal structure of compound 2 has been previously reported. However, we have explored the unusual enclathration of complex cationic moieties within the supramolecular host cavities formed by the molecular assembly of complex anionic moieties. The supramolecular assemblies obtained in the crystal structure have been further studied theoretically using DFT calculations, quantum theory of atoms-in-molecules (QTAIM) and non-covalent interaction plot (NCI plot) computational tools. Theoretical studies reveal that the combination of π-staking interactions (l.p-π, π-π and C–H···π) have more structure-guiding roles compared to the H-bonds. The large binding energy of π-stacking interactions in 2 is due to the antiparallel orientation of aromatic rings and their coordination to the metal centers, thereby increasing the contribution of the dipole–dipole interactions.

Iminophenol as a ligand or cation in cobalt(II and II,III) complexes: synthetic approaches, spectral and structural studies

New complexes [H2L]2CoCl4 (І) and [CoІІCоІІІCl2L3]H2O (ІІ), where HL is a condensation product of o-vanillin and methylamine, were synthesized and characterized by IR, UV/Vis spectroscopies, and X-ray structural analysis. For the synthesis of I, cobalt (II) chloride was used as a metal source, while for II, cobalt powder and its salt were used simultaneously. In the preparation of I, the use of methylamine hydrochloride contributed to the formation of tetrachlorocobaltate(II) with the protonated Schiff base H2L+as a cation. The monovalent cations are almost planar and show the presence of intramolecular O/N–HО hydrogen bonds. In the crystal, columns of cations connected by - stacking alternate with double-row columns of tetrahedral [CoCl4]2– anions and are additionally joined by a branched system of O/N–HCl hydrogen bonds. Crystal II is built of neutral molecules CoІІСоІІІCl2L3 and uncoordinated water molecules. In the molecule, the main CoІІІL3 fragment with a metal atom in the octahedral environment of three deprotonated ligands attaches a cobalt(II) atom at the CoIICoIII distance of 3.17 Å. The cobalt(II) atom has a highly distorted five-coordinate СоІІО3Cl2 environment formed by two bridging oxygen atoms of deprotonated phenoxy groups, the O atom of the methoxy group of the ligands, and two chlorine atoms. The obtained results allow us to propose the use of the metal salt+its powder combination for the purposeful synthesis of mixed-valent complexes of metals capable of exhibiting various oxidation states. Deliberate protonation of the Schiff base can be used to prepare organic-inorganic metal halide hybrids with functionalized cations.

Hydroxybenzoate salts of cobalt(II), manganese(II), and nickel(II): synthesis, crystal structure, Hirshfeld surface analyses, and thermal behavior

The reaction of hydroxybenzoates with divalent first row transition metal ions afforded four mononuclear complexes, [M(OH2)6](dhbzc)2·2H2O (M = Co2+, 1 or Mn2+, 2), [Ni(OH2)6](hbzc)2·2H2O (3) and [Ni(OH2)5(hbzc)](hbzc)·3H2O (4) (where dhbzc− = 2,6-dihydroxybenzoate and hbzc− = 4-hydroxybenzoate). The complexes were characterized by single crystal and powder X-ray diffraction analyses, infrared spectroscopy, and thermogravimetric analysis. Results showed that the hydrogen bonds present in dhbzc− impaired its coordination to Co2+ and Mn2+. Thereafter, Hirshfeld surface analyses (HS) and 2D fingerprint plots were used to investigate the intermolecular contacts in 1–4. The offset π···π stacking of the dhbzc− counterions in 1 and 2 lead to C···C close contacts over C···H/H···C ones. Complexes 3 and 4 presented the usual herringbone aromatic-based packing for the hbzc− rings with a predominance of C···H/H···C close contacts. The existence of water molecules in the crystal lattices of 1–4 was determined by TG analyses, which proved the presence of coordinated and uncoordinated water molecules. The thermal decomposition patterns were analyzed in light of the percentage of the strongest intermolecular close contacts.

Synthesis, Spectroscopic and X-Ray Structure Determination of a New Mononuclear Terbium (III) Complex from the Ligand N,N'-1,5-bis(pyridylmethylidene) Carbonohydrazone (H2L)

In the title compound, [Tb(H2L)2(H2O)3].3Cl.4(H2O).(C2H5OH), the Tb3+ is nine-coordinated in a distorted monocapped square antiprismgeometry by four nitrogen atoms, two oxygen atoms from the ligand molecules of the tridentate N,N'-1,5-bis(pyridylmethylidene) carbonohydrazone) (H2L) and three oxygen atoms of coordinating water molecules. The structure of the complex was elucidated by X-ray diffraction analysis. Suitable crystals were grown by slow evaporation of ethanol solution. The compound crystallizes in the triclinic crystal system with a space group of Pī. The asymmetric unit of the compound contains two neutral ligand molecules, oneterbium ion, three coordinated water molecules, five and half uncoordinated water molecules and one uncoordinated ethanol molecule. In the crystal, the complex cations are linked by hydrogen bonds into layers. These layers, chloride anions and non-coordinating water molecules are connected by O—H···O, O—H···N, O—H···Cl, N—H···O, N—H···Cl and C—H···Cl hydrogen bonds into a three-dimensional structure.

Recyclable luminescence sensor for Cu2+, Cr2O72− and CrO42− in water and acid/base vapor response based on water-stable bipyridyl-based Ln-MOFs

Detecting toxic contaminants in water, such as heavy metal ions and chromate ions, is important for public health and the environment. In the context, luminescence lanthanide-organic frameworks have been the competitive means to recognize such contaminants. Herein, two Ln-MOFs, [Ln3(L)2(HCOO)(H2O)5]·14H2O (H4L ​= ​2,6-di(2,4-dicarboxyphenyl)-4-(pyridine-4-yl)pyridine) (Ln ​= ​Eu, 1-Eu and Ln ​= ​Tb, 1-Tb), have been synthesized solvothermally by using the selection of the bipyridyl-tetracarboxylic ligand (H4L). Single-crystal X-ray diffraction indicates that this two Ln-MOFs are isostructural and contain uncoordinated pyridyl nitrogen atoms and water molecules, which provides the Lewis-base sites for detecting various small molecules. Moreover, both 1-Eu and 1-Tb exhibit excellent chemical stability in aqueous solution with the pH ranging from 2 to 13. Thanks to such characteristics, 1-Eu can be served as a multi-responsive luminescence sensor for Cu2+, Cr2O72− and CrO42− in deionized water, tap water and river water via luminescent quenching. Notably, the sensing processes toward Cu2+, Cr2O72− and CrO42− exhibit high selectivity and sensitivity, and good recyclability. The luminescence sensing mechanism was carefully studied by PXRD, XPS, and UV spectroscopy. In addition, 1-Eu also displays luminescence turn-off/on when alternately exposed to HCl and NH3 gases, which can mainly be attributed to the protonation/deprotonation process by the free bipyridyl N sites. The work illustrates 1-Eu could shed light on the exploration of MOF-based sensors for analytical applications.

Two high-spin cobalt(III) complex anions with pyridinium-based cations: synthesis, structural elucidation and magnetic properties

Two novel hybrid salts containing high spin tris(oxalato)cobaltate(III) complexes and pyridinium derivative isomer cations, viz. (C7H11N2)3[Co(C2O4)3]·nH2O (C7H11N2+ = 2-amino-4,6-dimethylpyridinium cation, n = 0 for salt 1; C7H11N2+ = 4-dimethylaminopyridinium, n = 4 for salt 2) were successfully isolated from aqueous solution. They were characterized using various physicochemical techniques, such as C, H, N microanalyses, thermogravimetric studies, FT-IR, UV-Vis, EDX, PXRD, single-crystal X-ray crystallography, and SQUID magnetometry. The size of the pyridinium derivative isomer cations has a major impact on the crystal structures. Salt 1 has a 3-D supramolecular framework formed by O–H···O hydrogen bonds between the high-spin [Co(C2O4)3]3− complex anion and the sterically encumbering 2-amino-4,6-dimethylpyridinium cations. The 3-D supramolecular framework of salt 2 is comprised of [Co(C2O4)3]3− complex anion, small size 4-dimethylaminopyridinium cations and uncoordinated water molecules via N–H···O and O–H···O hydrogen bonds. Structural cohesion is reinforced by π–π stacking interactions between the pyridine rings in both salts. Temperature-dependence magnetic moment (µ) collected under zero-field cooled (ZFC) and field-cooled (FC) conditions revealed robust antiferromagnetic ordering below TN = 25 K. The negative Weiss constant, θ = −55 K, confirmed the presence of antiferromagnetic interactions between Co(III) ions at low temperatures in 1 and the estimated effective magnetic moment of 4.5 μB supports the presence of the rare Oh high-spin Co(III) in this hybrid salt.

Spectroscopic studies, TD/DFT calculations, electrochemical, antibacterial, and Hirshfeld surface analysis of Ni(II) and Co(III) complexes based on 3-ethoxy salicylaldehyde

The ligand 2-(3-ethoxy-2-hydroxyphenyl)-4-methyl-1,2-dihydroquinazolin 3-oxide (HL1, H is the deprotonatable hydrogen) has been synthesized, and two metal complexes, namely [Ni(L2)2]·2CH3OH (1) and [Co(L2)2]·NO3·H2O (2) (where HL2 =1-(2-{[(E)-(3-ethoxy-2-hydroxybenzylidene]amino} phenyl)ethanone oxime) were obtained via complexation reaction between HL1 and nickel(II) acetate tetrahydrate or cobalt(II) nitrate hexahydrate. HL1 and both complexes were characterized by elemental analysis, as well as compared by spectroscopic methods such as FT-IR, UV–Vis and fluorescence spectroscopy. X-ray crystallography revealed that both complexes have distorted octahedral geometries but with a different configuration of the two tridentate (L2)– ligands around the metal centers. Complex 1 contained two lattice methanol molecules whereas 2 were counterbalanced by a nitrate anion beside an uncoordinated water molecule. The crystal structures show a 2-D and 3-D supramolecular architecture due to intermolecular interaction. Electrochemical properties of both complexes were tested by cyclic voltammetry and Electron paramagnetic resonance (EPR) spectroscopy of 2 was also investigated. Fascinatingly, antibacterial efficiencies of all compounds were compared. Furthermore, molecular electrostatic potential (ESP) was computed for both complexes to predict the reaction sites of electrophilic and nucleophilic attacks. Density Functional Theory (DFT) calculations were done to ascertain the optimum geometric configurations. The non-covalent interaction was determined using the Hirshfeld program.

Terephthalato and succinato bridged Mn(II) and Zn(II) coordination polymers involving structure-guiding H-bonded tetrameric assemblies: Antiproliferative evaluation and theoretical studies

Two new coordination polymers of Mn(II) and Zn(II) viz. {[Mn(µ-tp)(3-Ampy)2(H2O)2]2(3-Ampy)·2(H2O)}n (1) and {[Zn(µ-succ)(3-Ampy)2]·2H2O}n (2) (tp = terephthalate, 3-Ampy = 3-aminopyridine, succ = succinate) have been synthesized and characterized using elemental and spectroscopic analyses, TGA and single crystal X-ray diffraction techniques. Uncoordinated 3-AMpy and water molecules of the polymeric co-crystal hydrate 1 are involved in the formation of cyclic tetrameric {(3-Ampy)2(H2O)2} assembly which provide rigidity to the structure. The presence of guest 3-Ampy and water molecules in the voids of supramolecular Mn(II) host tetramer in 1 provides additional reinforcement to the crystal structure. The lattice water molecules of 2 are aggregated via non-covalent interactions to form discrete cyclic {(H2O)4} tetrameric clusters in the crystal structure. Density functional theory (DFT), non-covalent index (NCI) plot and quantum theory of atoms in molecules (QTAIM) computational analyses reveal that the supramolecular H-bonded cyclic tetrameric structure-guiding synthon in 1 and the (H2O)4 cyclic water clusters in 2 have significant energetic contribution towards the stability of the polymers. In vitro anticancer activities of the compounds considering trypan blue and apoptosis assays revealed that the compounds induce concentration dependent cytotoxicity in Dalton’s lymphoma (DL) cancer cells with nominal effects in normal peripheral blood mononuclear cells (PBMC) cells. Comparative analysis reveals that compound 2 induced higher apoptosis in DL cells; which is well consistent with the trypan blue exclusion assay. Molecular docking and pharmacophore modelling studies of the compounds reveal that the compound 2 significantly interacts with the antiapoptotic proteins to establish structure activity relationship (SAR).

Slow Phase Transition-Induced Scan Rate Dependence of Spin Crossover in a Two-Dimensional Supramolecular Fe(III) Complex

Slow Phase Transition-Induced Scan Rate Dependence of Spin Crossover in a Two-Dimensional Supramolecular Fe(III) Complex

Unsaturated coordination modes of Mn/V in manganese vanadate: Inner capture and surface migration of zinc ions for high performance zinc-ion battery

It was synthesized Mn0·2V2O5(H2O)·H2O (MnVO) porous microflowers and Ti0·055V2O5(H2O)2·H2O (TiVO) nanosheets. Rietveld refinements and high-angle annular dark-field (HAADF)-scanning transmission election microscope (STEM) reveal they are both constructed by two-dimensional (2D) V-O-V monolayers, lamellar hydrated metal ions and uncoordinated water molecules, in which all the V centers exhibit unsaturated coordination modes. Density functional theory (DFT) calculation proves that the exposed unsaturated V centers on the MnVO (001) surface can boost Zn2+ migration along the surface with a low barrier of 0.61 eV. Therefore, MnVO shows a dominant surface-controlled capacity. MnVO displays excellent Zn2+ storage behavior (435 mAh g-1 at 0.1 A g-1) with a capacity retention of 96.4 % after 1000 discharge/charge cycles at 5 A g-1, which is superior to TiVO. And MnVO and TiVO both show higher capacities than the commercial V2O5. Ex situ characterizations of MnVO discover a conversion of MnVO → Znm(MnVO) and a partial phase transformation mechanism of MnVO → Zn3(OH)2V2O7·2H2O during discharge/charge process. And DFT calculations reveal the intercalation of Zn2+ into some sites in the inner channel of MnVO is irreversible, leading to the accumulation of Zn2+ with almost unchanged interlayer spacing.

Syntheses, Characterization, and X-ray Crystal Structure of Binuclear Lanthanide Complexes Assembled with Schiff Base and Acetate

Herein we reported the binuclear complexes of the 1-(pyridin-2-yl)-2-(pyridin-2-ylmethylene)hydrazine ligand (HL) [Ln2(HL)2(CH3COO)6].n(H2O) (Ln = Y, Pr, Gd and Er). The binuclear complexes are characterized by IR and physical measurement. Spectroscopic evidence indicated that the Schiff base HL behave an N3 coordination tridentate ligand. The complexes are formulated as [{Ln(1-(pyridin-2-ylmethylidene-kN)-2-(pyridin-2-yl-kN)hydrazine-kN1)(h2-OOCH3)2}{h1:h2:m2-OOCH3}2{Ln(1-(pyridin-2-ylmethylidene-kN)-2-(pyridin-2-yl-kN)hydrazine-kN1))(h2-OOCH3)2}].n(H2O). The structure of the praseodymium complex was elucidated by X-ray diffraction analysis. Suitable crystals were grown by slow evaporation of methanol solution. The asymmetric unit of the compound contains two neutral ligand molecules, two Pr3+ ions, four acetate anions acting in h2-OOCH3 mode, two acetate anions acting in h1:h2:m2-OOCH3 mode, and three uncoordinated water molecules. The praseodymium atom is ten coordinated and the coordination sphere is best described as a distorted bicapped square antiprism. The PrIII···PrIII distance is 4.2777(6) Å and the bridging angle Pr—O—Pr and O—Pr—O are respectively 115.8(3)° and 64.2(3)°. The structure is consolidated by intra and intermolecular hydrogen bond.

Water in the Alluaudite Type-Compounds: Synthesis, Crystal Structure and Magnetic Properties of Co3(AsO4)0.5+x(HAsO4)2−x(H2AsO4)0.5+x[(H,□)0.5(H2O,H3O)0.5]2x+

In this study, a new cobalt arsenate belonging to the alluaudite supergroup compounds with the general formula of Co3(AsO4)0.5+x(HAsO4)2−x(H2AsO4)0.5+x[(H,□)0.5(H2O,H3O)0.5]2x+ (denoted as CoAsAllu) was synthesized under hydrothermal conditions. Its crystal structure was determined by a room-temperature single-crystal X-ray diffraction analysis: space group C2/c, a = 11.6978(8), b = 12.5713(7), c = 6.7705(5) Å, β = 113.255(5)°, V = 914.76(11) Å3, Z = 2 for As6H8Co6O25. It represents a new member of alluaudite-like protonated arsenates and the first alluaudite-like phase showing both protonation of the tetrahedral site and presence of the H2O molecules in the channels. In the asymmetric unit of CoAsAllu, one of the two Co, one of the two As and one of the seven O atoms lie at 4e special positions (site symmetry 2). The crystal structure consists of the infinite edge-shared CoO6 octahedra chains, running parallel to the [101¯] direction. The curved chains are interconnected by [(As1O4)0.5(H2As1O4)0.5]2− and [HAs2O4]2− tetrahedra forming a heteropolyhedral 3D open framework with two types of parallel channels. Both channels run along the c-axis and are located at the positions (1/2, 0, z) and (0, 0, z), respectively. The H2 and H4 hydrogen atoms of O2H2 and O4H4 hydroxyl groups are situated in channel 1, while the uncoordinated water molecule H2O7 at half-occupied 4e special positions and hydrogen atoms of O6H6 hydroxyl group were found in channel 2. The results of the magnetic investigations confirm the quasi one-dimensional structure of divalent cobalt ions. They are antiferromagnetically coupled with the intrachain interaction parameter of J ≈ −8 cm−1 and interchain parameter of J’ ≈ −2 cm−1 that become effective below the Néel temperature of 3.4 K.

One Pot Ultrasonic Assisted {[Ni(tptz)Cl(H2O)2][Ni(tptz)(H2O)3]}-3Cl.5H2O Complex Formation Using Triazine Ligand, XRD/HSA-Interactions, and Spectral and Thermal Investigation

Under room temperature ultrasonic conditions, mixing the neutral 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine (tptz) ligand with Ni(II) salt resulted in the preparation of a unique {[Ni(tptz)Cl(H2O)2]-[Ni(tptz)(H2O)3]}3Cl.5H2O complex with two different nickel(II) centers in a high yield. The crystal structure of {[Ni(tptz)Cl(H2O)2][Ni(tptz)(H2O)3]}3Cl.5H2O revealed the existence of distorted octahedral around both Ni(II) centers. The complex structure was further supported by FT-IR, UV-Vis., CHN-EA, TGA and EDX. The computed HSA was also performed to support the XRD interaction types. The existence of the H2O molecules in the crystal lattice was examined by FT-IR and TG/DTG measurements that proved the presence of coordinated and uncoordinated water molecules. Moreover, the thermal stability of the desired complex was evaluated at open atmosphere via TG/DTG and showed stability up to ~400 °C and multistep thermal decomposition.

Synthesis and crystal structure of catena-poly[[hexa-aqua{μ3-2-[bis-(carboxyl-atometh-yl)amino]-terephthalato}dicobalt(II)] penta-hydrate] containing water tapes and penta-mers.

The title coordination polymer, {[Co2(C12H7NO8)(H2O)6]·5H2O} n , was crystallized at room temperature from an aqueous solution of 2-aminodi-acetic terephthalic acid (H4adtp) and cobalt(II) nitrate. The asymmetric unit consists of one adtp4- ligand, one and two half CoII ions, six water ligands coordinated to CoII ions and five uncoordinated water mol-ecules. Two of the cobalt cations lie on centres of inversion and are coordinated in octa-hedral O2(OH2)4 environments, whereas the other adopts a slightly distorted octa-hedral NO3(OH2)2 environment. The crystal structure contains parallel stacked, one-dimensional zigzag chains, {[Co2(C12H7NO8)(H2O)6]} n , which assemble into a three-dimensional supra-molecular architecture via networks of hydrogen bonds involving the coordinated and free water mol-ecules. One-dimensional 'water tapes' are formed, containing alternating six-membered and twelve-membered rings of water mol-ecules, together with water penta-mers, in which a central uncoordinated water mol-ecule is hydrogen bonded to two coordinated and two free water mol-ecules in a tetra-hedral arrangement.

Synthesis, structural characterization and prospects for a new tris (5-methylbenzimidazole) tris (oxalato) ferrate(III) trihydrate complex as a promising antibacterial and antifungal agent

A new mononuclear complex (C8H9N2)3[Fe(C2O4)3].3H2O was synthesized via a conventional solution method and characterized by FT-IR and UV–visible spectroscopy, followed by thermal analysis and single crystal X-ray diffraction. The molecular structure of the complex reveals [Fe(C2O4)3]3− octahedral anions and 5-methylbenzimidazole (C8H9N2)+ cations, which are connected together through uncoordinated water molecules via O/NH⋯O hydrogen bonds. Face-to-face interactions (π–π stacking) between identical organic cations and O/NH⋯O hydrogen bonding lead to the formation of a three-dimensional supramolecular architecture. The optical absorbance of the complex was identified from a UV–visible study, showing an optical energy gap of 3.56 eV. The thermal property was evaluated by thermogravimetric analysis. The antibacterial effects of the synthesized iron(III)complexhave also been examinedin vitroagainst clinical bacterial strains: two Gram-positive and four Gram-negative, using the disk diffusion and macro-dilution broth methods. The obtained results show that the Fe(III)complexexhibits a marked antibacterial activity, associated with lysozyme and anti-biofilm potential. Furthermore, the results of antifungal studies by the agar well diffusion method demonstrated that our complex possesses higher activity against Candida albicans than the standards Amphotericin B and Fluconazole 25, which showed zone of inhibition diameters of about 19 and 13 mm, respectively, compared to 20 mm given by the new iron complex.