Monohydrate Complex Research Articles

Design of a cyanide ion optode based on immobilization of a new Co(III) Schiff base complex on triacetylcellulose membrane using room temperature ionic liquids as modifiers

A new cyanide optode was designed using [N,N′-bis(salicyliden)-2,3-diaminopyridine]tributylphosphine cobalt(III) percholorate monohydrate complex, which was coated on transparent triacetylcellulose film as membrane. The reduction in the absorbance value of the optode at the maximum wavelength of 380 nm was related to cyanide concentration in aqueous samples. The sensitivity of the method was improved by using room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate, [C 4MIM][PF 6], introduced in constructing the optode membrane. The linear dynamic range for the determination of cyanide was 1.0 × 10 −5 to 2.5 × 10 −4 M with a limit of detection of 4.2 × 10 −6 M ( n = 10) and a response time range of 7–10 min. The optode was successfully applied for the determination of cyanide in drinking water.

Structure, electronic and vibrational spectra and aromaticity of hemiporphyrazine and its hydrates: A density functional theory study

The hemiporphyrazine molecule, its tautomer with hydrogen atoms bonded to nitrogen atoms in pyridine rings, and hemiporphyrazine monohydrate complex have been studied by density functional theory (DFT) computations using the B3LYP hybrid method and triple- ζ valence basis sets. In gas phase the hemiporphyrazine molecule has non-planar equilibrium structure of C 2v symmetry, in contrast to the solid state where it is planar. Vibrational spectra (frequencies and IR intensities) of these molecules have also been calculated. UV–vis electronic spectra have been studied using time-dependent density functional theory (TDDFT). Theoretical characteristics are in good agreement with available experimental data. Aromaticity of all mentioned compounds has been evaluated using HOMA and NICS criteria. Additionally, structures of another hemiporphyrazine monohydrate with different bonding of water molecule as well as of hemiporphyrazine dihydrate were optimized in order to study hydrogen bonding in hemiporphyrazine hydrates.

Matrix Isolation Infrared Spectrum of the Sulfuric Acid−Monohydrate Complex: New Assignments and Resolution of the “Missing H-Bonded ν(OH) Band” Issue

The matrix isolation infrared spectra of "dry" and "wet" vapors of sulfuric acid have been investigated as trapped in solid argon matrices. The availability of a spectrum of trapped anhydrous acid vapor and its comparison with the spectra of trapped water containing vapors of the acid allowed the identification of the hydrogen-bonding shifted hydroxyl bands for both the acid and the water moieties of the monohydrated H(2)SO(4).H(2)O complex. The experimental results are compared to the various theoretically calculated wavenumber values of the acid and its monohydrated complex. The complex stabilization energies, as obtained from calculations and empirical correlations, are compared.

Synthesis, crystal structure, spectroscopic and electrochemical properties of nickel(II) dipicolinate complex with ethylisonicotinate

The diaqua(ethylisonicotinate)(pyridine-2,6-dicarboxylato)nickel(II) monohydrate complex was synthesized and characterized by spectroscopic (IR, UV/vis), X-ray diffraction and electrochemical methods. The Ni(II) ion is bonded to dipicolinate (dpc) through pyridine N atom and one O atom of each carboxylate group, two aqua ligands and N pyridine atom of ethylisonicotinate (ein), form the distorted octahedral geometry. The molecules are connected via O–H ··· O hydrogen bonds, forming motifs in three dimensional networks. IR and UV-Vis spectroscopies agree with the observed crystal structure. The voltammetric behaviour of the complex was investigated in aqueous solution by square-wave and cyclic voltammetry using a NH3/NH4Cl buffer. The square-wave voltammogram of the complex yields three reduction peaks at −0.88, −1.20 and −1.28 V. The irreversible reduction as a shoulder at −1.20 V is due to Ni-dpc-ein complex. The peak at −0.88 V corresponds to irreversible electrode process of Ni(II)-ein complex while the peak at −1.28 V is attributed to the reduction of the coordinated dpc ligands.

Infrared spectroscopy of anionic hydrated fluorobenzenes

We investigate the structural motifs of anionic hydrated fluorobenzenes by infrared photodissociation spectroscopy and density functional theory. Our calculations show that all fluorobenzene anions under investigation are strongly distorted from the neutral planar molecular geometries. In the anions, different F atoms are no longer equivalent, providing structurally different binding sites for water molecules and giving rise to a multitude of low-lying isomers. The absorption bands for hexa- and pentafluorobenzene show that only one isomer for the respective monohydrate complexes is populated in our experiment. For C6F6.-H2O, we can assign these bands to an isomer where water forms a weak double ionic hydrogen bond with two F atoms in the ion, in accord with the results of Bowen et al. [J. Chem. Phys. 127, 014312 (2007), following paper.] The spectroscopic motif of the binary complexes changes slightly with decreasing fluorination of the aromatic anion. For dihydrated hexafluorobenzene anions, several isomers are populated in our experiments, some of which may be due to hydrogen bonding between water molecules.

Synthesis, structure, spectroscopic and electrochemical properties of (2-amino-4-methylpyrimidine)-(pyridine-2,6-dicarboxylato)copper(II) monohydrate

The (2-amino-4-methylpyrimidine)-(pyridine-2,6-dicarboxylato)copper(II) monohydrate complex was synthesized and characterized by spectroscopic (IR, UV/Vis, EPR), thermal (TG/DTA) and electrochemical methods. X-ray structural analysis of the title complex revealed that the copper ion can be considered to have two coordination spheres. In the first coordination sphere the copper ion forms distorted square-planar geometry with trans-N 2O 2 donor set, and also the metal ion is weakly bonded to the amino-nitrogen in the layer over and to the carboxylic oxygen in the layer underneath in the second coordination sphere. The second coordination environment on the copper ion is attributed to pseudo octahedron. The powder EPR spectra of Cu(II) complex at room and liquid nitrogen temperature were recorded. The calculated g and A parameters have indicated that the paramagnetic centre is axially symmetric. The molecular orbital bond coefficients of the Cu(II) ion in d 9 state is also calculated by using EPR and optical absorption parameters. The cyclic voltammogram of the title complex investigated in DMSO (dimethylsulfoxide) solution exhibits only metal centered electroactivity in the potential range −1.25 to 1.5 V versus Ag/AgCl reference electrode.

Synthesis, crystal structure and spectrothermal characterization of zinc(II) salicylato complex with 2,2′-azobispyridine, [Zn(Hsal) 2(H 2O)(abpy)]·H 2O

The novel aqua(azobispyridine)bis(salicylato)zinc(II) monohydrate complex ( 1) was synthesized and characterized by means of elemental analysis, IR and UV-vis spectroscopy, thermal analysis and X-ray diffraction techniques. The crystal structure analysis indicates that the mononuclear 1 shows an s- cis/ E/ s- cis configured azobispyridine ligand, with the distortion from square pyramidal toward trigonal bipyramidal Zn(II) ion coordinated to one pyridyl and one azo N atom together with two carboxylate oxygen atoms and one aqua ligand. The crystal packing involves both hydrogen-bonding and π–π interactions. The title complex undergoes a thermochromic phase transition at ca. 189 °C, changing from 1 (brown complex) to 2 (purple complex) and the thermal decomposition of 1 proceeds in four stages.

Reaction of 1,2-bis(2,6-dicarboxypyridin-4-yl)ethyne with Co(II) generates coordination monomers not polymers: Crystal structure of 4-(2,6-dicarboxypyridin-4-yl)ethynylpyridine-2,6-dicarboxylatotriaqua cobalt(II) monohydrate

Reaction and crystallization of 1,2-bis(2,6-dicarboxypyridin-4-yl)ethyne with Co(II) produces crystals containing monomers of 4-(2,6-dicarboxypyridin-4-yl)ethynylpyridine-2,6-dicarboxylatotriaqua cobalt(II) monohydrate complex (1), [Co(C16H6N2O8)(H2O)3]·H2O, instead of a rigid 1-D metal–organic framework consisting of a linear coordination polymer. This complex crystallizes in the monoclinic space group C2/c with a=6.8028(9) A, b=36.781(5) A, c=7.5135(9) 2.474(2)° and Z=4. The complex sits on a symmetry axis such that the two halves of the molecule are related by two-fold rotation symmetry. The molecules form layers in which the molecules are joined by intermolecular O–H⋯O interactions involving hydrogen bonds between CO2H⋯CO2 −, H2O⋯CO2 −, H2O⋯CO2H and H2O⋯H2O groups.

Relative bioavailability of zinc in supplemental inorganic and organic sources for Nile tilapia Oreochromis niloticus fingerlings

A 90-day feeding experiment was conducted with sex reversed Nile tilapia (Oreochromis niloticus) fingerlings fed purified or practical diets supplemented with different zinc sources to evaluate fish growth performance and zinc and iron retention in fish bones, fillets, liver, skin and eyes. The relative bioavailability value (RBV) of zinc in the supplemental sources tested was also calculated. Fish were fed with isonitrogenous and isoenergetic purified or practical diets supplemented with 150 mg Zn kg−1, as zinc sulphate monohydrate (ZnSO4), zinc oxide (ZnO) or zinc amino acid complex (Zn-AA). The feeding trial was conducted in 30, 50 L aquaria where four 0.66 ± 0.01 g (mean ± SD) fingerlings were initially stocked. No significant differences were observed for any growth performance variables (P > 0.05). In practical diets, only ZnSO4 and ZnO presented bone zinc retention similar to that for the standard zinc source. Zinc concentration in the bone of fish fed practical diet supplemented with Zn-AA (171 ± 3.62 μg g−1) was significantly lower than that verified for the practical diets supplemented with the standard zinc source (200 ± 17.7 μg g−1) or with ZnSO4 (204 ± 19.9 μg g−1). Assuming the concentration of zinc in bones as the response criterion, the supplemental zinc RBV from ZnSO4 (105%) was higher than the RBV for Zn-AA (95.1%) or ZnO (94.9%). Iron concentration in the bones of animals fed the non-zinc-supplemented purified diet was significantly higher than that observed for purified diet supplemented with Zn-AA (P < 0,05). The results of the present work allowed us to conclude that ZnSO4 in relation to ZnO or Zn-AA was the supplemental zinc source with higher zinc bioavailability to Nile tilapia.

Crystal Structure of Ammonium(2.2.2‐cryptand) Thiocyanate Monohydrate

Crystals of the ammonium (2.2.2‐cryptand) thiocyanate monohydrate complex, [NH4(2.2.2‐Crypt)]+ × SCN- · H2O, were studied by X‐ray structural analysis: space group P2/c, a = 11.303(2)*angst;, b = 8.313(1)A, c = 14.392(3)A, β = 110.39(2)°, Z = 2, 3680 independent measured reflections, R = 0.064. This complex is of the guest–host type: the cryptand ligand cavity contains the NH4+ cation with statistically disordered H atoms forming H bonds with each of its O and N heteroatoms. The SCN- anions and H2O molecules are linked by H bonds to form chains that are infinite along the z axis.

CdS nanoparticles modified to chalcogen sites: new supramolecular complexes, butterfly bridging, and related optical effects.

All present approaches to surface modification of nanoparticles (NPs) with organic ligands exploit metal (cadmium) sites as anchor points. To obtain efficient interaction of NP surface with p-orbitals of organic chromophores, we utilize the chalcogen (sulfur) sites on the NP surface. These sites present several advantages stemming from a stronger interaction of their atomic orbitals with both modifier and NP core. The chalcogen modification of CdS was achieved by using a mixed ligand (2,2'-bipyridyl-N,N')(malonato-O,O')-copper(II) monohydrate complex. The weak monodentate ligands (water) are replaced by a copper-sulfur bond during the modification reaction. The structure of the product was investigated by optical spectroscopy, electron spin resonance, and nuclear magnetic resonance. The modified NP can be described as a few tens (<40) of (2,2'-bipyridyl-N,N')(malonato-O,O')-copper units attached to the CdS core. Steady-state and time-resolved luminescence measurements, molecular orbital calculations, and UPS data indicate that delocalized surface states enveloping the surface chalcogen atoms of NP, transition metal, and p-orbitals of the bipyridine ligand are present in the synthesized species. The delocalized states are made possible due to the bridging of p-levels of sulfur and pi-orbitals of bipyridine by butterfly d-orbitals of the transition metal atom placed between them. Chalcogen-modified NP can be considered as a new member of the family of supramolecular compounds based on transition metal complexes. Both NP and metal complex parts of the prepared supramolecules are very versatile structural units, and new molecular constructs of similar design, in which quantum effects of NPs are combined with optical properties of transition metal complexes, can be obtained with different NPs and metal complexes.

Crystal structures of molecular complexes of 18-crown-6 with 2-aminobenzoic and 5-amino-1-benzyl-1,2,3-triazole-4-carboxylic acid hydrazides

The crystal structures of two host-guest molecular complexes of 18-crown-6 with 2-aminobenzoic acid hydrazide monohydrate (the ratio host: guest: H2O = 1: 2: 2) (complex I) and 5-amino-1-benzyl-1,2,3-triazole-4-carboxylic acid hydrazide (the host: guest ratio = 1: 2) (complex II) are determined by X-ray diffraction analysis. Crystals I are monoclinic, a = 8.468(2) A, b = 17.378(3) A, c = 10.517(2) A, β = 96.88(3)°, space group P21/n, and R = 0.0393 for 6692 reflections. Crystals II are orthorhombic, a = 18.489(1) A, b = 10.192(3) A, c = 20.412(2) A, space group Pbca, and R = 0.0540 for 3513 reflections. In both complexes, the centrosymmetric 18-crown-6 and guest molecules are joined together through the NH⋯O (crown) hydrogen bonds, which involve all the hydrogen atoms of the hydrazine group. The NH⋯O=C intramolecular hydrogen bond is observed in the guest molecule. In structure I, the water molecule serves as a bridge between the guest molecules related by the glide-reflection plane and combines the guest-host-guest complexes into layers. In structure II, the guest molecules are linked into chains through hydrogen bonds of the NH⋯O=C type; in turn, the chains composed of guest molecules and the crown ether molecules bonded to these chains form a layered structure.

Synthesis, Crystal Structure, and IR Absorption Spectra of the Adduct of Copper(II) Acetate Monohydrate with 1-Amino-4-aza-9-fluorenone Cu2(CH3COO)4(H2O)2· C12H8N2O

The crystal structure of the adduct of copper(II) acetate monohydrate and 1-amino-4-aza-9-fluorenone Cu2(CH3COO)4(H2O)2· C12H8N2O was determined. The structure is layered; the layers are formed by alternating columns of copper(II) acetate monohydrate complexes and columns of dimers of 1-amino-4-aza-9-fluorenone. The layered structure of the adduct is stabilized by a hydrogen bonding system. Changes in the IR absorption spectra due to the formation of the adduct were discussed.

A Method for the Preparation of the cis-Bis(Glycinato)Copper(II) Monohydrate Complex in the Solid State

A method has been described for the preparation of the bis(glycinato)copper(II) monohydrate complex in the cis form in the solid state. The complex was characterised by IR spectra, elemental analyses and X-ray spectroscopy using a compact X-ray diffraction analyser. The blue complex prepared in the solid phase has an identical structure when compared with one prepared by the wet method.

Polymorphism of Inclusion Complexes and Unsolvated Hosts. III. Dimorphism of the Alkaloid Colchicine Hydrate. The Structure of Colchicine Monohydrate

The alkaloid colchicine forms, in addition to the previously known dihydrate host–guest complex, a monohydrate complex. The crystal structure of the monohydrate was determined by direct methods and refined to a final R value of 0.046 for 1425 observed reflections. Crystal data are: orthorhombic, space group P2 12 12 1, a = 9.145(2) A; b = 13.270(3) A; c = 17.942(4) A, V = 2177(1) A3, Z= 4, Dx = 1.22 g cm-3, T = 293 K. The conformation of the molecule is practically identical with the conformation in the dihydrate inclusion complex. Water molecules show proton donor as well as proton acceptor properties and are hydrogen bonded with the three colchicine molecules giving rise to the three dimensional H-bonded network.

Crystal structure of valinomycin-monohydrate cage complexes crystallized from dioxane.

Valinomycin, cyclo-[(L-Val-D-Hyv-D-Val-L-Lac)3-], was crystallized from aqueous dioxane solvent as a monohydrate complex in which water molecules were found within the ion-binding cavity of the ionophore: monoclinic P2(1), a = 14.377 (3), b = 41.554 (14), c = 14.080 (3) A, beta = 118.27 (2) degrees, Z = 4. There are two non-equivalent valinomycin-water complexes and three dioxane molecules in the asymmetric unit. The ionophore molecules adopt two similar but non-identical, octahedral, bracelet, cage conformations that are a consequence of two distinct ways in which the complexed water molecules can deform the normal octahedral coordinate geometry of the metal binding site. In the first complex the water molecule forms hydrogen donor bonds to the carbonyl oxygens of two L-valine residues on one facial side of the cavity, while in the second complex the water molecule is trigonal-planar coordinate and binds to two L-valine residues on one entrant face of the cavity plus a third D-valine residue from the opposite side of the cavity.

Preparation and Characterization of Zinc(II) and Palladium(II) Complexes with Dipyrido[14]Annulenes

Abstract The reaction of 5, 14-dihydro-7, 16-diethyl-(E)-or-(Z)-di-pyrido[b,i][1,4,8,11]tetraazacyclotetradecine with bis(2,4-pen-tanedionato)aquazinc(II) led to the corresponding zinc(II) mono-hydrate complexes, while the reaction with sodium tetrachloro-palladate(II) yielded the corresponding palladium(II) complexes. Judging from the behavior of electronic and 1H-n.m.r. spectra, the zinc(II) complexes are presumed to exist in aggregate species in a relatively high concentration range. Mass, i.r., u.v.-visible, and 13C-n.m.r. data are also presented.

Crystal and molecular structure of (N,N'-dimethyl-2,11-diaza[3.3](2,6)pyridinophane)copper dichloride monohydrate complex

Crystal and molecular structure of (N,N'-dimethyl-2,11-diaza[3.3](2,6)pyridinophane)copper dichloride monohydrate complex

ChemInform Abstract: Interaction of Metal Ions with Humic‐like Models. Part 9. Synthesis, Structure, and Spectroscopic and Magnetic Properties of catena‐μ‐Aquo‐diaquobis(2,6‐dimethoxybenzoato)metal(II) Monohydrate Complexes of Manganese, Cobalt, Nickel, and Zinc. X‐Ray Crystal Structure of (Co(dmba)2(H2O)3)·H2O.

AbstractThe title complexes (I) are prepared by reaction of stoichiometric amounts of the metal sulfate or acetate with the ligand in hot aqueous solution at pH 4‐5 (no yields given).

Separation of the cis/ trans isomers of bis(L-aspartato)- and tris-(L-alaninato)chromium(III) complexes. Kinetic studies on the ring-opening of isomers of bis-L-(aspartato) chelate

Bis-(L-aspartato)chromiumII) trihydrate and tris(L-alaninato)-chromium(III) monohydrate complexes were prepared according to literature methods [1]. The isomers in each of these complexes were separated using a CM Sephadex cation exchanger and sodium iodate as the eluting solvent. Characterization of the isomers was by elemental analysis and spectroscopy. The kinetics of the ring-opening of the aspartatochelating complex was monitored at constant [H +].