Uncoordinated Water Research Articles

A new one-dimensional 3D supramolecular coordination polymer of CdII based on pyrazine and 3-nitropththalic acid: Synthesis, characterization, crystal structure, thermal analysis

ABSTRACTA one-dimensional coordination polymer of CdII based on pyrazine (pz) and 3-nitrophthalic acid (3-nphaH2), namely poly[[diaqua bis(3-nitro-2-carboxylato-1-carboxylic acid)(µ2-pyrazine) cadmium(II)]dihydrate], {[Cd(3-nphaH)2(pz)(H2O)2]. 2H2O}n, was prepared and characterized. The asymmetric unit consists of one CdII center, two (3-nphaH)– anions, two halves of two crystallographically distinct pz ligands, two coordinated and two uncoordinated water molecules. The CdII cation is surrounded by four oxygen atoms from two (3-nphaH)– and two water molecules as well as two nitrogen atoms from two pz ligands in distorted octahedral geometry. Complicated hydrogen bonding network accompanied with N–O···π and C–O···π stacking interactions leads to formation of a 3D supramolecular network. Commonly, this kind of C–O–π and N–O···π interaction is detected in electron-rich CO/NO groups of (3-nphaH)– ligand and electron-deficient π-system of pyrazine.

Synthesis, spectroscopic, thermal, biological, morphological and molecular docking studies of the different quinolone drugs and their cobalt(II) complexes

New six cobalt(II) complexes 1–6 with four generation of quinolone drugs (nalidixic acid (Nal), oxolonic acid (Oxo), pipemidic acid (Pip), lomefloxacin (Lom), pefloxacin mesylate (Pef) and levofloxacin (Lev)) have been synthesized in methanol medium, and the general formula was designed as [Co(L)2(Cl)2(H2O)2]·4H2O (L=Nal (1), Oxo (2), Pip (3), Lom (4), Pef (5), and Lev (6)). The Co(III) complexes were identified using micro–analytical, FT–IR spectroscopy, conductance data, effective magnetic moments, electronic UV–vis spectra, and thermal analyses. The six quinolone drug chelates acts as uni–dentate via nitrogen atom of pyridone/piperazyl moiety. Electronic spectroscopic tools are in agreement with an octahedral geometrical structure. Thermal degradation analyses TG–DTG in nitrogen gas environmental are discussed the number and location of water molecules. The thermal decomposition process is completely in 3–4 steps, that the first step is responsible to loss of four uncoordinated water molecules. The stabilities of Co(II) complex 1–6 were studied dependent on activations of energy E*, entropy ΔS*, enthalpy ΔH* and Gibbs free energy ΔG* that have been estimated using Coats–Redfern and Horowitz–Metzeger non–isothermal methods. Molecular docking was used to predict the binding between some quinolone drugs with the receptor of breast cancer mutant 3hb5-oxidoreductase. The structural view of the synthesized cobalt(II)-quinolone nanoparticles has been documented with the help of transmission electron microscope (TEM). The synthesized metal chelates have been screened in vitro antibacterial activity against bacteria, gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) and two strains of fungus (Aspergillus flavus and Candida albicans). The cobalt(II) chelates were shown to possess more antibacterial activity than the free chelates.

Land-Water-Security Nexus: Changing Geopolitics in the Nile Basin Cooperative Framework Agreement

This article extends the debate on the shift in water security governance in the Nile Basin countries. Water as an object of analysis was previously embedded in a depoliticized governance framework now faces politicization in the context of food, energy and climate change. In considering land-water-security nexus, population and climate variations drive Middle East and North Africa (mena) policies for the return of the state primacy in water governance. As Egypt and Sudan maintain their dynamics of hegemony in Nile Basin countries, Gulf States however are deploying proxy water diplomacy through investment in agricultural farmlands in Nile Basin countries. Increasing number of actors alter water access and security across formal and informal domains. The Nile Basin Cooperative Agreement (cfa) remains contested between upstream and downstream riparian states as being uncoordinated water management and development policies. Incorporating market and local users beyond the state gets politicized in securing water security. In view of this, this article hence suggests that power relations are not static, but subject to the changing circumstances. Egypt’s water security would be more sustainable when it engages cfa countries in a joint coordination and development projects.

Experimental and Theoretical Investigation of the Anti-Ferromagnetic Coupling of CrIII Ions through Diamagnetic -O-NbV-O- Bridges.

The synthesis and properties of a novel hetero-tetranuclear compound [Cr2(bpy)4(μ-O)4Nb2(C2O4)4]·3H2O (1; bpy = 2,2'-bipyridine), investigated by single-crystal X-ray diffraction, magnetization measurements, IR, UV/visible spectroscopy, electron paramagnetic resonance (EPR; X- and Q-bands and high-field), and density functional theory (DFT) calculations, are reported. Crystal structure of 1 (orthorhombic Pcab space group) consists of a square-shaped macrocyclic {Cr2(μ-O)4Nb2} core in which CrIII and NbV ions are alternately bridged by oxo ions and three uncoordinated water molecules. The intramolecular CrIII···CrIII distances through the -O-NbV-O- bridges are 7.410(2) and 7.419(2) Å, while diagonal separation is 5.406(2) Å. The temperature dependence of magnetization M(T) evidences an anti-ferromagnetic ground state, which originates from a magnetic interaction between two CrIII ions of spin 3/2 through two triatomic -O-NbV-O- diamagnetic bridges. A spin Hamiltonian appropriate for polynuclear isolated magnetic units was used. The best-fitting curve for this model is obtained with the parameters gCr = 1.992(3), J = -12.77(5) cm-1, and |D| = 0.17(4) cm-1. The CrIII···CrIII dimer model is confirmed by EPR spectra, which exhibit a pronounced change of their shape around the temperature corresponding to the intradimer coupling J. The EPR spectra simulations and DFT calculations reveal the presence of a single-ion anisotropy that is close to being uniaxial, D = -0.31 cm-1 and E = 0.024 cm-1.

Crystal structure, Hirshfeld surface analysis, thermal behavior and IR investigation of a new organic selenate-selenide [C3H12N2]2(SeO4)(SeO3)·4H2O

The new hybrid compound called propane-1,3-diammonium selenate-selenide tetrahydrate (PDASe) was obtained by slow evaporation and characterized by X-ray diffraction, NMR and IR spectroscopies, TGA and DSC analysis and UV–visible transmittance.This compound contains both SeIV in the form of selenide (SeO32−) trigonal pyramids and SeVI as selenate (SeO42−) tetrahedra. The structure is built up from tunnels containing all the components of the structure and oriented along b axis. The organic and inorganic groups are linked together by two types of hydrogen bonds, O–H⋯O and N–H⋯O. Crystal structure and Hirshfeld surfaces analysis revealed that the compound were mainly supported by N–H⋯O and O–H⋯O intermolecular interactions and the uncoordinated water molecules play a key role in the construction of the 3D stacking motif.The dehydration and the decomposition of the title compound are confirmed by the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The analysis by the UV visible spectroscopy confirmed the transparency of our compound in the visible region.

Dihydroxo-bridged dimeric Cu(II) system containing sandwiched non-coordinating phenylacetate anion: Crystal structure, spectroscopic, anti-bacterial, anti-fungal and DNA-binding studies of [(phen)(H2O)Cu(OH)2Cu(H2O)(phen)]2L.6H2O: (HL = phenylacetic acid; phen = 1,10-phenanthroline)

This paper reports the synthesis, X-ray crystal structure, DNA-binding, antibacterial and antifungal studies of a rare dihydroxo-bridged dinuclear copper(II) complex including 1,10-phenanthroline (Phen) ligands and phenylacetate (L) anions, [Cu2(Phen)2(OH)2(H2O)2].2L.6H2O. Structural data revealed distorted square-pyramidal geometry for each copper(II) atom with the basal plane formed by the two nitrogen atoms of the phenantroline ligand and the oxygen atoms of two bridging hydroxyl groups. The apical positions are filled by the oxygen atom from a water molecule. This forms a centrosymmetric cationic dimer where the uncoordinated phenylacetate ligands serve to balance the electrical charge. The dimers interact by means of hydrogen bonds aided by the coordinated as well as uncoordinated water molecules and phenyl-acetate moieties in the crystal lattice. The binding ability of the complex with salmon sperm DNA was determined using cyclic voltammetry and absorption spectroscopy yielding binding constants 2.426 × 104 M−1 and 1.399 × 104 M−1, respectively. The complex was screened against two Gram-positive (Micrococcus luteus and Bacillus subtilis) and one Gram-negative (Escherichia coli) bacterial strains exhibiting significant activity against all the three strains. The complex exhibited significant, moderate and no activity against fungal strains Mucor piriformis, Helminthosporium solani and Aspergillus Niger, respectively. These preliminary tests indicate the competence of the complex towards the development of a potent biological drug.

In-Situ Copper(II) Complexes of Some Quinolone Drug Ligands Were Discussed for Their Molecular Structures: Synthesis in Binary Solvent

A series of copper solid complexes with different generation of quinolone drugs of the type [Cu(L)n(Cl)x(H2O)y]·zH2O ((1) L: nalidixic acid (Nal), n = 2, x = 2, y = 2, z = 9; (2) L: oxolonic acid (Oxo), n = 2, x = 2, y = 2, z = 2; (3) L: pipemidic acid (Pip), n = 2, x = 2, y = 2, z = 4; (4) L: lomefloxacin (Lom), n = 2, x = 2, y = 2, z = 2; (5) L: pefloxacin mesylate (Pef), n = 2, x = 2, y = 2, z 2; (6) L: levofloxacin (Lev), n = 2, x = 2, y = 2, z = 2) were synthesized and identified using micro-analytical, FT-IR spectroscopy, conductance data, effective magnetic moments, electronic UV-vis spectra, electron-spin-resonance (ESR) spectra. Except levofloxacin that behaves as bi-dentate fashion through oxygen atoms of pyridone and carboxylate groups, the other quinolone drug chelates acts as uni-dentate via nitrogen atom of pyridone/piperazyl moiety. Electronic spectroscopic tools are in agreement with an octahedral geometrical structure. Thermal degradation analyses TG-DTG in nitrogen gas environmental are discussed the number and location of water molecules. The thermal decomposition process is completely in 3–5 steps, that the first step is responsible to loss of uncoordinated water molecules. The stabilities of Cu(II) complex 1–5 were studied dependent on activations of energy E*, entropy ΔS*, enthalpy ΔH* and Gibbs free energy ΔG* that have been estimated using Coats-Redfern and Horowitz-Metzeger non-isothermal methods. Molecular docking was used to predict the binding between some quinolone drugs with the receptor of breast cancer mutant 3hb5-oxidoreductase.

Synthesis and spectroscopic studies of levofloxacin uni-dentate complexes of Ru(II), Pt(IV) and Ir(III): Third generation of quinolone antibiotic drug complexes

The monobasic unidentate levofloxacin (LEV; (S)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methylpiperazin-1-yl)-7-oxo-7H-pyrido[1,2,3-de]-1,4―benzoxazine-6-carboxylic acid) complexes of Ru(III), Pt(IV) and Ir(III) were prepared and well discussed using elemental analyses (CHN), molar conductance, infrared, electronic, effective magnetic moment, 1H-NMR, X-ray powder diffraction, scanning electron microscopy, transmittance electron microscopy and thermogravimetric (TG/DTG) analyses. The IR and electronic spectra of LEV complexes with their assignments were discussed in details which were confirmed that LEV is binding to the metal ions as a neutral unidentate ligand through the nitrogen atom of 4-methylpiperazin-1-yl moiety. The molar ratio of Ru(III) and Ir(III) chelates is 1:3 (Metal: LEV), while Pt(IV) complex has a 1:2M ratio. The general formulas of LEV complexes have been designed as [M(L)n(Cl)x]·yH2O ((1) M=Ru3+, L: LEV, n=3, x=3, y=8; (2) M=Pt4+, L: LEV, n=2, x=4, y=4 and (3) M=Ir3+, L: LEV, n=3, x=3, y=6. The X-ray powder diffraction was used as technique to estimate the particle size of LEV complexes. Thermogravimetric analysis (TG-DTG) was utilized to identify the presence of coordinated, uncoordinated water molecules, mass losses and residual products.

Biomimetic Transformation by a Crystal of a Chiral MnII–CrIII Ferrimagnetic Prussian Blue Analogue

We present a case of a concerted sequence of several characteristic biological reactions such as electron transfer, mixed valency, proton or ion motion, and dehydration–rehydration occurring in a single crystal and its associated phase transformations. It provided a unique opportunity to look for accurate pictures of sequence mimicking biological function using crystallography. Here, we report the observation of a reversible musclelike action associated with proton motion between ammonium and coordinated and uncoordinated water molecules in unison in which the whole X-ray diffraction study (including eight structure determinations as a function of temperature and cycling through two phase transformations) was performed in situ on a single crystal of the chiral molecular magnet [MnII(R-pnH)(H2O)][CrIII(CN)6]·H2O [R-pn = (R)-1,2-propanediamine]. In addition, the reversible structural change in dimensionality from two- to three-dimensional is observed with an increase in the ferrimagnetic Curie temperature f...

Synthesis, crystal structures, thermal decomposition mechanism and thermal properties of mononuclear ternry lanthanide complex with 2,4-dichlorobenzoic acid and 2,2′:6′,2″-terpyridine

The study of lanthanide complexes combining with aromatic-carboxylic acids has attracted extensive attention, according to their diverse coordination types and fascinating properties. In addition, a wide variety of applications including gas separation and storage, non-linear optics, electroluminescent materials, luminescent bioprobes, and catalysis have been utilized as functional materials. Lanthanide cations have the unique optical, electrical, and magnetic properties. However, the properties can be changed and even improved to be applied to more wider fields through the interactions between lanthanide cations and carboxylic acid ligands. Therefore, we chosen 2,4-dichlorobenzoic acid (2,4-DClHBA) as the main ligands, and 2,2′:6′,2″-terpyridine (terpy) as auxiliary ligands to validly sensitize the lanthanide metal ions to assemble one novel mononuclear lanthanide complex 2,4-DClBA: 2,4-dichlorobenzoate; terpy: 2,2′:6′,2″-terpyridine ([Ho(2,4-DClBA)3(terpy)(H2O)]·H2O). We dissolve 2,4-DClHBA (0.6 mmol) and terpy (0.2 mmol) in ethanol (95%) and adjust the solution at the pH of 5–7 with the prepared NaOH solution (1 mol/L). Add the mixed ligands solution to LnCl3·6H2O (0.2 mmol) aqueous solution under stirring and deposit it for 12 h. The complex was structurally characterized by elemental analysis, single crystal, powder X-ray diffraction, Infrared spectra and Raman spectrometry. The results revealed that the diffraction peak of complex is almost in agreement with simulated data, showing that the structure of the powder of complex is similar with the pure crystal. The detailed IR-R spectra of complex shows the spectrum of complex is different from the two ligands, the stretching vibration peak at 1549 cm - 1 attributed to the C=N bonds in terpy takes place red shift to 1537 cm - 1, The v C=O (1631 cm - 1) of free carboxylic acid ligand completely disappears in the spectra of the complex and appear two another new absorption peak at 1553 and 1437 cm - 1, which are attributed to the asymmetric stretching vibration ( v asCOO - ) and the symmetric stretching vibration ( v sCOO - ) of the carboxylic group, indicating the target product has been produced. Single crystal X-ray diffraction reveals that complex crystallize in the triclinic space group P ī and each Ho3+ ion is nine-coordinated adopting a distorted monocapped square antiprismatic molecular geometry. Mononuclear complex are stitched together via hydrogen bonding and π - π interactions to form the 1D, 2D, 3D supramolecular structures. The thermal decomposition mechanism complex was measured by TG-DTG-DSC/FTIR coupling technique, which shows the uncoordinated water all lose firstly, coordinated water and terpy are resolved into CO2 and other gaseous molecules. At last, the 2.4-DClBA are decomposed into CO2, CO and other gaseous molecules. Based on the above analysis, the general thermal decomposition reaction of the complexes is related to the structure and the decomposition of the framework occurs above 403.15 K, indicating the complex has thermal stability. The average molar heat capacity value of the complex gradually increased with the augment of temperature and its heat capacities fitted to a polynomial equation. Finally, the derived thermodynamic functions ( H T– H 298.15), ( S T– S 298.15) and ( G T– G 298.15) of the complex relative to the standard reference temperature 298.15 K were also obtained. Kinetics of the first decomposition stage for the complex was calculated by integral iso-conversional non-linear (NL-INT) method. It is obviously to observe that the activation energy E of the the complex varies with α respectively, indicating the first thermal decomposition stage for complex is complex reactions.

Supramolecular complexes of Co(II), Ni(II) and Zn(II) p-hydroxybenzoates with caffeine: Synthesis, spectral characterization and crystal structure

Three novel complexes Co(II), Ni(II) and Zn(II) containing p-hydroxybenzoates and caffeine ligands were synthesized and characterized by elemental analysis, FT-IR and UV–vis Spectroscopy, molar conductivity and single crystal X-ray diffraction methods. The thermal properties of the synthesized complexes were investigated by TGA/DTA. The general formula of the complexes is [M(HOC6H4COO)2(H2O)4]·2(C8H10N4O2)·8H2O (where: M: Co, Ni and Zn). The IR studies showed that carboxylate groups of p-hydroxybenzoate ligands have monodentate coordination mode. The M2+ ions are octahedrally coordinated by two p-hydroxybenzoate ligands, four water molecules leading to an overall MO6 coordination environment. The medium-strength hydrogen bondings involving the uncoordinated caffeine ligands and water molecules, coordinated and uncoordinated water molecules and p-hydroxybenzoate ligands lead to three-dimensional supramolecular networks in the crystal structures.

Complexation of different transition metals with 4,4′-dimethyl-2,2′-bipyridine: Crystal structure, UV spectra and Hirshfeld surfaces

Four new complexes, [Co(dmbpy)2(dca)2]·CH3OH (1), [Ni(dmbpy)2(dca)2]·CH3OH (2), [Zn(dmbpy)2(dca)2]·(3) and [Cu(dmbpy)2(OH)2]·5H2O (4) (dca=dicyanamide), derived from 4,4′-dimethyl-2,2′-bipyridine (dmbpy) have been synthesized and characterized by elemental analysis, TGA and single-crystal X-ray diffraction. Crystal structures and Hirshfeld surfaces analysis revealed that the complexes 1–3 were mainly supported by OH⋯N, CH⋯N and π⋯π intermolecular interactions, and for complex 4, the uncoordinated water molecules play a key role in the construction of the 3D stacking motif. UV spectrum measurements demonstrate that all of the complexes show typical metal to ligand charge transfer (MLCT) absorption bands between 301 and 306nm. Moreover, after complexation, the absorption maximum bands about intraligand π→π* transitions similarly show slightly red shift compared to dmbpy ligand, consisting with the DFT calculations.

Layered vanadyl (IV) nitroprusside: Magnetic interaction through a network of hydrogen bonds

The hydrogen bond and π-π stacking are two non-covalent interactions able to support cooperative magnetic ordering between paramagnetic centers. This contribution reports the crystal structure and related magnetic properties for VO[Fe(CN)5NO]·2H2O, which has a layered structure. This solid crystallizes with an orthorhombic unit cell, in the Pna21 space group, with cell parameters a=14.1804(2), b=10.4935(1), c=7.1722(8) Å and four molecules per unit cell (Z=4). Its crystal structure was solved and refined from powder X-ray diffraction data. Neighboring layers remain linked through a network of hydrogen bonds involving a water molecule coordinated to the axial position for the V atom and the unbridged axial NO and CN ligands. An uncoordinated water molecule is found forming a triple bridge between these last two ligands and the coordinated water molecule. The magnetic measurements, recorded down to 2K, shows a ferromagnetic interaction between V atoms located at neighboring layers, with a Curie-Weiss constant of 3.14K. Such ferromagnetic behavior was interpreted as resulting from a superexchange interaction through the network of strong OH····OH2O, OH····NCN, and OH····ONO hydrogen bonds that connects neighboring layers. The interaction within the layer must be of antiferromagnetic nature and it was detected close to 2K.

Synthesis, structure and characterization of five new organically templated metal sulfates with 2-aminopyridinium.

The chemistry of organically templated metal sulfates has attracted interest from the materials science community and the development of synthetic strategies for the preparation of organic-inorganic hybrid materials with novel structures and special properties is of current interest. Sulfur-oxygen-metal linkages provide the possibility of using sulfate tetrahedra as building units to form new solid-state materials. A series of novel organically templated metal sulfates of 2-aminopyridinium (2ap) with aluminium(III), cobalt(II), magnesium(II), nickel(II) and zinc(II) were obtained from the respective aqueous solutions and studied by single-crystal X-ray diffraction. The compounds crystallize in centrosymmetric triclinic unit cells in three structure types: type 1 for 2-aminopyridinium hexaaquaaluminium(III) bis(sulfate) tetrahydrate, (C5H7N2)[Al(H2O)6](SO4)2·4H2O, (I); type 2 for bis(2-aminopyridinium) tris[hexaaquacobalt(II)] tetrakis(sulfate) dihydrate, (C5H7N2)2[Co(H2O)6]3(SO4)4·2H2O, (II), and bis(2-aminopyridinium) tris[hexaaquamagnesium(II)] tetrakis(sulfate) dihydrate, (C5H7N2)2[Mg(H2O)6]3(SO4)4·2H2O, (III); and type 3 for bis(2-aminopyridinium) hexaaquanickel(II) bis(sulfate), (C5H7N2)2[Ni(H2O)6](SO4)2, (IV), and bis(2-aminopyridinium) hexaaquazinc(II) bis(sulfate), (C5H7N2)2[Zn(H2O)6](SO4)2, (V). The templating role of the 2ap cation in all of the reported crystalline substances is governed by the formation of characteristic charge-assisted hydrogen-bonded pairs with sulfate anions and the presence of π-π interactions between the cations. Additionally, both coordinated and uncoordinated water molecules are involved in hydrogen-bond formation. As a consequence, extensive three-dimensional hydrogen-bonding patterns are formed in the reported crystal structures.

Supramolecular hydrogen-bonding patterns in the organic-inorganic hybrid compound bis(4-amino-5-chloro-2,6-dimethylpyrimidinium) tetrathiocyanatozinc(II)-4-amino-5-chloro-2,6-dimethylpyrimidine-water (1/2/2).

Zinc thiocyanate complexes have been found to be biologically active compounds. Zinc is also an essential element for the normal function of most organisms and is the main constituent in a number of metalloenzyme proteins. Pyrimidine and aminopyrimidine derivatives are biologically very important as they are components of nucleic acids. Thiocyanate ions can bridge metal ions by employing both their N and S atoms for coordination. They can play an important role in assembling different coordination structures and yield an interesting variety of one-, two- and three-dimensional polymeric metal-thiocyanate supramolecular frameworks. The structure of a new zinc thiocyanate-aminopyrimidine organic-inorganic compound, (C6H9ClN3)2[Zn(NCS)4]·2C6H8ClN3·2H2O, is reported. The asymmetric unit consist of half a tetrathiocyanatozinc(II) dianion, an uncoordinated 4-amino-5-chloro-2,6-dimethylpyrimidinium cation, a 4-amino-5-chloro-2,6-dimethylpyrimidine molecule and a water molecule. The Zn(II) atom adopts a distorted tetrahedral coordination geometry and is coordinated by four N atoms from the thiocyanate anions. The Zn(II) atom is located on a special position (twofold axis of symmetry). The pyrimidinium cation and the pyrimidine molecule are not coordinated to the Zn(II) atom, but are hydrogen bonded to the uncoordinated water molecules and the metal-coordinated thiocyanate ligands. The pyrimidine molecules and pyrimidinium cations also form base-pair-like structures with an R2(2)(8) ring motif via N-H...N hydrogen bonds. The crystal structure is further stabilized by intermolecular N-H...O, O-H...S, N-H...S and O-H...N hydrogen bonds, by intramolecular N-H...Cl and C-H...Cl hydrogen bonds, and also by π-π stacking interactions.

The effect of ligand substituent on crystal packing: Structural and theoretical studies of two Ga(III) supramolecular compounds

A new Ga(III) supramolecular compound (4,4′-bipyH2)[Ga(hpydc)2]2·7H2O (2) (where H2hpydc = 4-hydroxy-pyridine-2,6-dicarboxylic acid and 4,4′-bipy = 4,4′-bipyridine) was synthesized using the proton transfer reaction. Compound 2 was structurally characterized using single crystal X-ray diffraction, and it was shown that its asymmetric unit consists of two independent anionic Ga(III) complexes, one fully protonated 4,4′-bipyridine and seven uncoordinated water molecules. In order to understand the effect of pyridine OH substituent on supramolecular interactions and crystal packing, compound 2 was compared with (bipyH2)[Ga(pydc)2]·(H2pydc)·4H2O (1) (where H2pydc = pyridine-2,6-dicarboxylic acid), that does not have an OH group on the pyridine ligand. The Density Functional Theory (DFT) and Natural Bond Orbital (NBO) calculations and also Atoms in Molecules (AIM) analysis were used to analyze the non-covalent interactions in both complexes. The calculation of non-covalent interactions' energy provides a useful means to investigate their effects in the crystal packing.

Synthesis, Crystal Structures, and Luminescent Properties of Mononuclear Cu(II)/Ni(II) Complexes Containing N-Donor Ligands

The two mononuclear complexes containing N-donor ligands [Cu(phen)2Cl]·(5-SIPH2)·3H2O (1) and [Ni(phen)3]·2(5-SIPH2)·2H2O (2) (5-SIP = 5-sulfoisophthalate anion, phen = 1,10-phenanthroline) were synthesized by the slow solvent evaporation method. For complex 1, the copper ion is five-coordinated, which is coordinated by the two 1,10-phenanthroline molecules and a chloride ion to form a [Cu(phen)2Cl]+ cation. The three uncoordinated water molecules connect the [Cu(phen)2Cl]+ cations and (5-SIPH2)– anions to form three-dimensional network structure through the hydrogen bonds. For complex 2, the nickel ion is six-coordinated, which coordinates with three 1,10-phenanthroline molecules to generate the [Co(phen)3]2+ cation. The two free water molecules connect the (5-SIPH2)– anions to form a three-dimensional network structure through the hydrogen bonds. In the two complexes, the (5-SIPH2)– anions only balance the charges. The complexes exhibit the luminescence properties with emission maximum at 420 and 442 nm at room temperature, respectively. CCDC: 1007213, 1; 1007214, 2.

Synthesis, Crystal Structure, and Luminescent Property of One-Dimensional Chain Coordination Polymer [Cu(1,6-nds)(py)4]n·2.5nH2O

The copper coordination polymer [Cu(1,6-nds)(py)4]n·2.5nH2O (1,6-nds = 1,6-naphthalenedisulfonate anion, py = pyridine) was synthesized in water by the reflux method. The characterization results of X-ray single crystal diffraction show that the coordination polymer has a one-dimensional chain structure, the two sulfonate groups of 1,6-naphthalenedisulfonate anion bridge with two copper ions by coordination bonds. The copper ion also coordinates with four pyridine molecules. The uncoordinated water molecules interconnect with each other, and also connect to the complex molecules via hydrogen bonds. The coordination polymer displays a strong fluorescence emission peak centered at 462 nm.

A two-dimensional cadmium(II) polymer based on nicotinic acid and thiocyanate ligands.

A cadmium-thiocyanate complex, poly[[bis(nicotinic acid-κN)di-μ-thiocyanato-κ(2)N:S;κ(2)S:N-cadmium(II)] monohydrate], {[Cd(NCS)2(C6H5NO2)2]·H2O}n, was synthesized by the reaction of nicotinic acid, cadmium nitrate tetrahydrate and potassium thiocyanide in aqueous solution. In the crystal structure, each Cd(II) cation is in a distorted octahedral coordination environment, coordinated by the N and S atoms of nicotinic acid and thiocyanate ligands. Neighbouring Cd(II) cations are linked together by thiocyanate bridges to form a two-dimensional network. Hydrogen-bond interactions between the uncoordinated solvent water molecules and the organic ligands result in the formation of the three-dimensional supramolecular network.

Synthesis, characterization and biological activities of metal(II) dipicolinate complexes derived from pyridine-2,6-dicarboxylic acid and 2-(piperazin-1-yl)ethanol

The new water-soluble and air stable compounds (H2ppz)[Co(dipic)2]·6H2O (1), (H2ppz)[Ni(dipic)2]·6H2O (2) and (H2ppz)[Zn(dipic)2]·6H2O (3) were prepared by the reaction of corresponding metal(II) acetates and a proton transfer salt, (H2ppz) (Hdipic)2, (4) of pyridine-2,6-dicarboxylic acid (H2dipic) and 2-(piperazin-1-yl)ethanol (ppz). The compounds 1–3 were characterized by elemental, IR, UV–vis. thermal analyses, magnetic measurement and single crystal X-ray diffraction studies. The molecular structures of the title compounds consist of one 1-(2-hydroxyethyl)piperazine-1,4-diium (H2ppz+2) cation, one bis(pyridine-2,6-dicarboxylate)metal(II) [M(dipic)2]2− anion, and six uncoordinated water molecules. In compounds 1–3 the metal ions coordinate to two oxygen and one nitrogen atoms of two pyridine-2,6-dicarboxylate molecules forming an octahedral environment. Antimicrobial activities against Gram (−) wild type (Escherichia coli and Pseudomonas aeruginosa), Gram (+) wild type (Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus and Bacillus subtilis) and clinical isolate (Morganella morganii, Proteus vulgaris and Enterobacter aeruginosa) were also studied. The results were reported, discussed and compared with the corresponding starting materials ((H2ppz) (Hdipic)2 (4), H2dipic and ppz). MIC (Minimal Inhibition Concentration) values of the newly synthesized compounds were determined as 4000 μg/ml (except B. subtilis and clinical isolate E. aeruginosa, >4000 μg/ml).