Phenylalanine-Based Co2+ and Cd2+ 1D Coordination Polymers: Structural Properties and Catalytic Application for Solvent-Free Aerobic Oxidation of Cycloalkene.

Two 1D coordination polymers (CPs) with general formula [M(L)(H2O)(AcO)]n, (M = Co (1) or Cd (2), AcO = acetate anion and L denotes l-phenylalanine based ligand), were synthesized and fully characterized by various spectroscopies (UV-vis, FTIR, and NMR), thermal techniques, magnetic measurements (for 1), and single-crystal and powder X-ray diffraction studies. They can be described as "ribbon-like" 1D polymers constructed through a zigzag arrangement. The polymeric structure is developed due to the coordination mode adopted by the amino acid ligand, classified as µ3-N1O1:O1:O2, which simultaneously links three metal centers. This moiety also plays an important role as a magnetic coupler between metal centers in the cobalt system, which shows a weak antiferromagnetic interaction. Both CPs have also been used in the catalytic oxidation of cyclohexene with molecular oxygen (O2) as an oxidant. Under mild conditions, both compounds demonstrated remarkable catalytic activity, with the cobalt system being more efficient than the cadmium analogue (conversion: 73 and 58% and selectivity for the major product, 2-cyclohexanone: 63 and 55%, for 1 and 2, respectively). Leaching experiments and the results obtained using a radical quencher are consistent with a radical-mediated mechanism for the Co compound. The presence of the superoxide radical was also confirmed using EPR spectroscopy and DMPO as a spin trap, which was further validated by DFT calculations. The activity observed for the Cd analogue is attributed to the organic scaffold assisted by the templating effect of the metal ion.

Tuning the Emission of Homometallic DyIII, TbIII, and EuIII 1-D Coordination Polymers with 2,6-Di(1H-1,2,4-triazole-1-yl-methyl)-4-R-phenoxo Ligands: Sensitization through the Singlet State.

This work reports the structural characterization and photophysical properties of DyIII, TbIII, and EuIII coordination polymers with two phenoxo-triazole-based ligands [2,6-di(1H-1,2,4-triazole-1-yl-methyl)-4-R-phenoxo, LRTr (R = CH3; Cl)]. These ligands permitted us to obtain isostructural polymers, described as a 1D double chain, with LnIII being nona-coordinated. The energies of the ligand triplet (T1) states were estimated using low-temperature time-resolved emission spectra of YIII analogues. Compounds with LClTr present higher emission intensity than those with LMeTr. The emission of TbIII compounds was not affected by the different excitation wavelengths used and was emitted in the pure green region. In contrast, DyLMeTr emits in the blue-to-white region, while the luminescence of DyLClTr remains in the white region for all excitation wavelengths. On the other hand, EuIII compounds emit in the blue (ligand) or red region (EuIII) depending on the substituent of the phenoxo moiety and excitation wavelength. Theoretical calculations were employed to determine the excited states of the ligands by using time-dependent density functional theory. These calculations aided in modeling the intramolecular energy transfer and rationalizing the optical properties and demonstrated that the sensitization of the LnIII ions is driven via S1 → LnIII, a process that is less common as compared to T1 → LnIII.

Lanthanide SMMs Based on Belt Macrocycles: Recent Advances and General Trends.

Enhancement of axial magnetic anisotropy is the central objective to push forward the performance of Single-Molecule Magnet (SMM) complexes. In the case of mononuclear lanthanide complexes, the chemical environment around the paramagnetic ion must be tuned to place strongly interacting ligands along either the axial positions or the equatorial plane, depending on the oblate or prolate preference of the selected lanthanide. One classical strategy to achieve a precise chemical environment for a metal centre is using highly structured, chelating ligands. A natural approach for axial-equatorial control is the employment of macrocycles acting in a belt conformation, providing the equatorial coordination environment, and leaving room for axial ligands. In this review, we present a survey of SMMs based on the macrocycle belt motif. Literature systems are divided in three families (crown ether, Schiff-base and metallacrown) and their general properties in terms of structural stability and SMM performance are briefly discussed.

Luminescence of Macrocyclic Mononuclear DyIII Complexes and Their Immobilization on Functionalized Silicon-Based Surfaces.

Two mononuclear DyIII complexes, [Dy(L1)(NCS)3] (Dy-EDA) and [Dy(L2)(NCS)3] (Dy-DAP), where Ln (n = 1-2) corresponds to a macrocyclic ligand derived from 2,6-pyridinedicarboxaldehyde and ethylenediamine (L1) and 1,3-diaminepropane (L2) were immobilized on functionalized silicon-based surfaces. This was achieved by the microcontact printing (µCP) technique, generating patterns on a functionalized surface via covalent bond formation through the auxiliary -NCS ligands present in the macrocyclic complex species. With this strategy, it was possible to control the position of the immobilized molecules on the surface. Water contact angle measurements, X-ray photoelectron spectroscopy (XPS), infrared reflection absorption spectra (IRRAS), and atomic force microscopy (AFM) confirmed that the surfaces were successfully functionalized. Furthermore, the optical properties in a broad temperature range were investigated for the as-prepared compounds. At room temperature, Dy-EDA was shown to emit in the deep blue region (Commission Internationald'Eclairage (CIE): (0.175, 0.128)), while Dy-DAP in the white region (CIE: (0.252, 0.312)). The different CIE values were due to the contribution of the strong emission of the ligand in the case of Dy-EDA. Besides, surface photoluminescence measurements showed that the immobilized complexes retained their bulk emissive properties.

Enhancement of Terbium(III)-Centered Luminescence by Tuning the Triplet Energy Level of Substituted Pyridylamino-4-R-Phenoxo Tripodal Ligands.

A series of luminescent phenoxo-bridged dinuclear TbIII complexes with tripodal ligands, 2,2'-[[(2-pyridinylmethyl)imino]di(methylene)]-bis(4-R-phenol), where R = CH3 (LCH3) (I), Cl (LCl) (II), CH3O (LCH3O) (III), COOCH3 (LCOOCH3) (IV), were prepared to probe the effect of para-substitution on the phenol ring of the ligand on the TbIII luminescence. For these TbIII complexes a complete suppression of the ligand-centered fluorescence is observed, which demonstrates an efficient ligand-to-metal energy transfer. Complex IV was found to be the one that shows the greater intensity of the emission at room temperature. The obtained quantum yields follow the trend IV > II ≫ I > III. The quantum yield for II and IV is approximately five times greater than those obtained for I and III, indicating that the LCl and LCOOCH3 are better sensitizers of the TbIII ions. These results were rationalized in terms of the variation of the energy gap between the triplet level (T1) of the ligand and the emissive 5D4 level of TbIII, due to the electron-acceptor or electron-donor properties of the substituents. The τav values are in the millisecond range for all the studied complexes and resulted independent of temperature. The Commission International d'Eclairage coordinates (CIE) for all complexes are in the green color region, being insensitive to the variation of temperature. Moreover, the color purity (CP) is ca. 90% for all complexes, being ca. 100% for IV. Thus, the introduction of electron-acceptor substituents on the ligand permitted us to improve the luminescent properties of the TbIII complexes.

Tuning White Light Emission in Dinuclear Phenoxo Bridged DyIII Complexes.

A new series of dinuclear dysprosium(III) complexes, [Dy2(LCH3)2(NO3)2(MeOH)2] (I), [Dy2(LCH3)2(NO3)2(DMF)2]·2DMF (II), [Dy2(LCl)2(NO3)2(DMF)2]·2DMF (III), and [Dy2(LCH3O)2(NO3)2(DMF)2] (IV), with 2,2'-[[(2-pyridinylmethyl)imino]di(methylene)]bis(4-R-phenol), where R = CH3, Cl, and CH3O, were investigated as potential white light emitters. All octacoordinated dysprosium(III) are phenoxo-bridged species and have a similar coordination environment. Nevertheless, I has a MeOH ligand molecule, while for II-IV a DMF ligand replaces that of MeOH. The nature of the coordinated solvent molecule plays an important role in the behavior of the thermal dependence of the Y/B (yellow/blue) emission ratio of the DyIII complexes (Y: 4F9/2 → 6H13/2, yellow and B: 4F9/2 → 6H15/2, blue transitions),, since for I the variation of this ratio is significant, while for the other DyIII complexes with DMF as ligand the ratio remains constant within experimental error. At room temperature the CIE (Commission International d'Eclairage) color coordinates for the DyIII complexes, I (0.286, 0.317), III (0.302, 0.324), and IV (0.322, 0.348) are close to the NTSC (National Television System(s) Committee) standard value for white color. Varying the temperature from 16 to 300 K the CIE coordinates for I change from the blueish to white region of the chromaticity diagram, while those of II present an inverse thermal dependence as compared to I. The CCT (Correlated Color Temperature) values at room temperature for I (8384 K), II (17235 K), and IV (5948 K) permit us to consider these complexes as candidates for white cold light emitters, the high value of II being uncommon. For I and II the CCT values vary strongly with temperature, showing a decrease with increasing temperature for I, and an increase with increasing temperature for II, thus making evident the influence on the photophysical properties of the nature of the coordinated solvent molecule in these complexes.

1D magnetic interactions in Cu(II) oxovanadium phosphates (VPO), magnetic susceptibility, DFT, and single-crystal EPR.

We report the crystal face indexing and molecular spatial orientation, magnetic properties, electron paramagnetic resonance (EPR) spectra, and density functional theory (DFT) calculations of two previously reported oxovanadium phosphates functionalized with Cu(II) complexes, namely, [Cu(bipy)(VO2)(PO4)]n (1) and [{Cu(phen)}2(VO2(H2O)2)(H2PO4)2 (PO4)]n (2), where bipy = 2,2'-bipyridine and phen = 1,10-phenanthroline, obtained by a new synthetic route allowing the growth of single crystals appropriate for the EPR measurements. Compounds 1 and 2 crystallize in the triclinic group P1̅ and in the orthorhombic Pccn group, respectively, containing dinuclear copper units connected by two -O-P-O- bridges in 1 and by a single -O-P-O- bridge in 2, further connected through -O-P-O-V-O- bridges. We emphasize in our work the structural aspects related to the chemical paths that determine the magnetic properties. Magnetic susceptibility data indicate bulk antiferromagnetism for both compounds, allowing to calculate J = -43.0 cm(-1) (dCu-Cu = 5.07 Å; J defined as Hex(i,j) = -J Si·Sj), considering dinuclear units for 1, and J = -1.44 cm(-1) (dCu-Cu = 3.47 Å) using the molecular field approximation for 2. The single-crystal EPR study allows evaluation of the g matrices, which provide a better understanding of the electronic structure. The absence of structure of the EPR spectra arising from the dinuclear character of the compounds allows estimation of weak additional exchange couplings |J'| > 0.3 cm(-1) for 1 (dCu-Cu = 5.54 Å) and a smaller value of |J'| ≥ 0.15 cm(-1) for 2 (dCu-Cu = 6.59 Å). DFT calculations allow evaluating two different exchange couplings for each compound, specifically, J = -36.60 cm(-1) (dCu-Cu = 5.07 Å) and J' = 0.20 cm(-1) (dCu-Cu =5.54 Å) for 1 and J = -1.10 cm(-1) (dCu-Cu =3.47 Å) and J' = 0.01 cm(-1) (dCu-Cu = 6.59 Å) for 2, this last value being in the range of the uncertainties of the calculations. Thus, these values are in good agreement with those provided by magnetic and single-crystal EPR measurements.

Unusual conformation of a dinuclear paddle wheel copper(II) complex. Synthesis, structural characterization and EPR studies.

An unusual and unique conformation of a paddle wheel type binuclear copper(II) complex containing acetate and acetamido ligands, {Cu2(µ2-O2CCH3)4}(OCNH2CH3) (1), was obtained by solvothermal synthesis. The structural characterization of this compound shows that the apical (acetamido) ligands are disposed at a 62° dihedral angle, generating a special conformation as a consequence of the synthetic method used. This conformation has not been reported in other paddle wheel copper(II) tetraacetate compounds. Electron paramagnetic resonance (EPR) spectra of powder samples of (1) were obtained at 9.5 and 33.8 GHz, while single crystal spectra were obtained at 33.8 GHz with a B0 applied in three orthogonal planes. The fit of the single crystal experimental data allowed gave g∥ = 2.345 ± 0.003, and g⊥ = 2.057 ± 0.005. The angular variation of the EPR line allows evaluation of the fine structure of (1), giving D = -0.337 ± 0.002 cm(-1) and E = -0.005 ± 0.001 cm(-1). The line width angular dependence, used together with the Anderson model and Kubo-Tomita theory, permitted the interdimer interaction to be evaluated as |J'| = (0.051 ± 0.002) cm(-1). Using the powder spectral temperature dependence it was possible to evaluate the intradinuclear exchange coupling constan J0 as -101 ± 2 cm(-1), which is considerably lower than that reported for other analogous copper(II) tetraacetate paddle wheel compounds (Cu(II)-PW), showing the remarkable effect of the conformation of the terminal ligands on the magnetic interaction.

The layered structure of poly[[hexaaqua(µ4-benzene-1,2,4,5-tetracarboxylato)dicopper(II)] tetrahydrate].

In the structure of the title compound, {[Cu2(C10H2O8)(H2O)6]·4H2O}n, the benzene-1,2,4,5-tetracarboxylate ligand, (btec)(4-), is located on a crystallographic inversion centre in a µ4-coordination mode. The coordination environment of each pentacoordinated Cu(II) centre is square pyramidal (SBP), formed by three water molecules and two carboxylate O atoms from two different (btec)(4-) ligands. The completely deprotonated (btec)(4-) ligand coordinates in a monodentate mode to four Cu(II) atoms. The alternation of (btec)(4-) ligands and SBP Cu(II) centres leads to the formation of a planar two-dimensional covalent network of parallelograms, parallel to the ab plane. Hydrogen bonds between a basal water molecule and an apical one from an adjacent [Cu(btec)0.5(H2O)3] unit exist in the intralayer space. Hydrogen bonds are also present between the two-dimensional network and the water molecules filling the channels in the structure.

Influence of symmetry on the magneto-optical properties of a bifunctional macrocyclic DyIII complex.

In this work, a novel complex, [Dy(LPr)(NO3)2]·(H2O)·(NO3) (1), containing a highly distorted macrocyclic ligand (LPr) and weak axial anions (NO3-), was synthesized and characterized. Even though this coordination environment is not ideal for maximizing the magnetic anisotropy of a DyIII ion, a magneto-structural analysis reveals that the high distortion of the macrocycle promotes a disposition of the hard plane and easy axis opposite to the expected one. This results in a quite symmetrical environment which allows obtaining a field induced SMM behaviour. The magnetic relaxation properties of this complex were rationalized with the aid of ab initio multireference calculations. Moreover, 1 showed the characteristic emission bands of DyIII ion, indicating that the macrocyclic ligand acts as an efficient sensitizer in the energy transfer process to the emissive state of the DyIII ion. Due to the symmetric environment of 1, the Y/B intensity ratio (0.61) results in CIE coordinates (0.278; 0.314), close to those of the white light region. To gain further insight into the mechanism leading to the luminescence properties, ab initio calculations were performed to elucidate the key factors controlling the Y/B intensity ratio in this bifunctional complex.

Dual visible and near-infrared luminescence in mononuclear macrocyclic erbium(III) complexes via ligand and metal centred excitation.

Considering the structural design of some of the scarce molecular-based Er-centred emitters in the literature, we explored the optical properties of three ErIII hexaazamacrocyclic complexes, namely Er-EDA (1), Er-OPDA(2) and Er-DAP(3). The macrocyclic ligands in these complexes differ in the lateral spacers, and are derived from 2,6-pyridine-dicarbaldehyde and ethylenediamine (EDA), ortho-phenylenediamine (OPDA) or 1,3-diaminopropane (DAP). Upon ligand-centred excitation, the bluish-green and green emissions of the ErIII ion were detected only for the complexes containing macrocycles with aliphatic spacers (1 and 3), which evidenced that these ligands can sensitize the ErIII luminescence. On the other hand, the ligand derived from the aromatic diamine (2) does not sensitize the ErIII luminescence. Energy transfer mechanisms, temperature sensing, CIE coordinates and CCT values were analyzed. Besides the excitation in the ligands, the erbium-centred excitation at 980 nm allowed the detection, in all cases, of bluish-green, green and red up-converted emissions, and also the downshifted NIR emission. The possible mechanisms involved in these transitions were described and analyzed according to the available data.

Exchange interactions through π-π stacking in the lamellar compound [{Cu(bipy)(en)}{Cu(bipy)(H2O)}{VO3}4]n.

Structural, magnetic, and powder and single-crystal electron paramagnetic resonance (EPR) studies were performed on [{Cu(bipy)(en)}{Cu(bipy)(H(2)O)}{VO(3)}(4)](n) (bipy = 2,2'-bipyridine, en = ethylenediamine), which is a new copper-vanadium hybrid organic-inorganic compound containing Cu(II) and V(V) centers. The oxovanadium units provide an anionic scaffolding to the structure, where two types of Cu(II) coordination modes, octahedral (Cu1) and square pyramidal (Cu2), contribute to the magnetic properties. The crystal structure contains layers including Cu1 and Cu2 ions, separated by stacked arrangements of 2,2'-bipyridine molecules. Each type of Cu(II) ion in these layers forms parallel spin chains described by exchange coupling parameters J(1) and J(2) for Cu1 and Cu2, respectively (exchange couplings defined as H(ex)(i,j) = -J(ij)S(i)S(j)), which, for necessity, are assumed to be equal to J. These chains are coupled by much weaker Cu1-Cu2 exchange interactions J(3) connecting neighbor Cu1 and Cu2 ions within a layer, through paths acting as rungs of a ladder chain structure. The average coupling J, which is antiferromagnetic (J < 0), according to the susceptibility data, is estimated with similar results with a mean field approximation (J = -1.4 cm(-1)), and with a uniform chain model (J = -1.7 cm(-1)). The EPR spectra of powdered samples and oriented single crystals are shown to be independent of J(1) and J(2), but are dependent on the weak coupling J(3), and the data allow a lower limit to be established: |J(3)| > 0.04 cm(-1). The spectra are also strongly sensitive to extremely weak coupling interactions with average magnitude J(4) between copper atoms in neighboring layers, separated by ∼10 Å, using the stacked 2,2'-bipyridine molecules, which produce a 2D-to-3D quantum phase transition. This is observed in single-crystal samples when the energy levels are changed with the orientation of the magnetic field. From the characteristics of these transitions, we estimate a value of |J(4)| = 0.0034 ± 0.0004 cm(-1) between Cu(II) ions in neighboring layers. This work emphasizes the important possibilities of EPR to evaluate extremely small exchange couplings between metal ions in a solid material, even in the presence of other much larger couplings.

Control of magnetic anisotropy by macrocyclic ligand distortion in a family of DyIII and ErIII single molecule magnets.

A family of hexaazamacrocyclic lanthanide complexes, [Ln(Ln)(NCS)3] (LnIII = Dy, Er; n = 1-3) has been synthesized and characterized by single-crystal X-ray diffraction, magnetic measurements and ab initio calculations. Macrocyclic ligands (Ln) differ in the lateral spacers, which are aliphatic chains with two and three carbons (for Ln, n = 1 and 2, respectively), and an aromatic ring for Ln = 3. Modification of the macrocycle spacer tunes planarity and rigidity of the equatorial coordination for both oblate (Dy) and prolate (Er) lanthanide ions. Ac-susceptibility studies showed that four of the six complexes are field induced single molecule magnets (SMMs). Trends in magnetic relaxation properties are rationalized with the aid of ab initio multireference calculations, highlighting the combined influence of macrocycle planarity, lanthanide electronic density distribution and intermolecular interactions for the achievement of slow demagnetization.

New Highly Charged Iron(III) Metal-Organic Cube Stabilized by a Bulky Amine.

In this work, we report a new octanuclear cluster based on FeIII and the ligand 1H-imidazole-4,5-dicarboxylic acid, [Et3NH]12[Fe8(IDC)12]·10DMF·13H2O (1), with a metal core containing eight FeIII connected by only one type of organic ligand. A peak at 573 m/z in the mass spectra of the compound suggests the adduct species {[Fe8(IDC)12]+8H}4-. By X-ray photoelectron spectroscopy, the oxidation state of the iron cation was confirmed to be 3+, also identifying the presence of a quaternary nitrogen species, which act as a countercation of the anionic metal core [Fe8(IDC)12]12-. Mössbauer spectra recorded at different temperatures show an isomer shift and quadrupole splitting parameters that confirm the existence of only FeIII-HS in the structure of 1. X-ray analysis reveals that compound 1 crystallizes in the orthorhombic system space group Ibam, confirming a molecular cluster structure with an almost regular cube as geometry, with the FeIII atoms located at the corners of the cube and connected by µ-1κ2 N,O:2κ2 N',O‴-IDC3- bridges. Additionally, the magnetic measurements reveal a weak antiferromagnetic coupling in the Fe8 III coordination cluster (J = -3.8 cm-1). To the best of our knowledge, 1 is the first member of the family of cubes assembled with 1H-imidazole-4,5-dicarboxylic acid and FeIII cation, exhibiting high pH stability over a broad pH range, making it an ideal candidate for the design of supramolecular structures and metal-organic frameworks.

Crystal structure and magnetic properties of a new chiral manganese(II) three-dimensional framework: Na(3)[Mn(3)(HCOO)(9)].

A structural and magnetic characterization of a trinuclear chiral Mn(II) formate three-dimensional framework exhibiting a triangular arrangement is presented. Compound Na(3)[Mn(3)(HCOO)(9)] was obtained by solvothermal synthesis and crystallizes in the chiral cubic space group P2(1)3 and is well described by a Delta conformation. The structure displays triangular Mn(3) building blocks, in which the metal centers are bonded by formate ligands in a syn-anti mode (Mn-Mn 5.697(1) A). The coordination sphere of manganese(II) is completed by six oxygen atoms from six formate ligands, resulting in an octahedral geometry. Magnetic susceptibility measurements showed antiferromagnetic interactions at high temperature and a strongly field dependent magnetic behavior below 40 K. At fields higher than 1.0 kOe only the antiferromagnetic interactions can be observed. At applied fields lower than 1.0 kOe magnetic susceptibility becomes irreversible with maxima observed at 22 and 34 K. These maxima suggest a weak ferromagnetic behavior because of spin canting, allowed by the presence of the noncentrosymmetric syn-anti HCOO bridges linking the Mn sites. This non-collinear antiferromagnetism and irreversible behavior can be due to the existence of a high degree of frustration in this unique lattice composed of linked triangular arrangements of interacting magnetic centers.

Mononuclear and polynuclear copper(II) complexes derived from pyridylalkylaminomethylphenol polypodal ligands.

Four mononuclear complexes [Cu(HL(1))Cl]PF(6).CH(3)OH (1), [Cu(HSL(1))Cl]PF(6).0.75H(2)O (2), [Cu(HL(2))Cl]PF(6).CH (3)OH (3), [Cu(HSL(2))Cl]PF(6).1.5CH(3)OH (4), and two polynuclear complexes [Cu (2)(SL(2))(2)](PF(6))(2).2CH(3)OH (5) and {Cu[Cu(SL(2))(Cl)](2)}(PF(6))(2) (6) (HL(1): 2-[(bis(2-pyridylmethyl)-amino)methyl]-4-methylphenol; HSL(1): 2-[(bis(2-pyridylmethyl)amino) methyl]-4-methyl-6-(methyl-thio)phenol; HL(2): 2-[(2-pyridylmethyl)(2'-pyridylethyl)-aminomethyl)]-4-methylphenol; HSL(2): 2-[(2-pyridylmethyl)(2'-pyridylethyl)amino-methyl]-4-methyl-6-(methylthio)phenol were obtained and characterized. The crystal structures of the mononuclear complexes 1-4 show the copper centers in a square-base pyramidal environment with the phenolic oxygen coordinated at the axial position. Dinuclear complex 5 has two copper centers with different geometry and bridged by phenoxo oxygens; one of the copper atoms is square pyramidal while the other can be described with a highly distorted octahedral geometry with a long Cu-S distance (2.867 A). Density functional theory calculations were used to obtain the reported structure of 6, since single crystals suitable for X-ray diffraction were not isolated. Magnetic studies done for 5 and 6 show an antiferromagnetic behavior for 5 (J = -134 cm(-1)) and a ferromagnetic behavior for 6 (J = +11.9 cm(-1)). Redox potentials for the mononuclear complexes were measured by cyclic voltammetry; the values show the effect of the chelating ring size (-213 mV and -142 mV for Cu-HL(1) and Cu-HL(2), respectively) and the presence of the thiomethyl substituent (-213 mV and -184 mV for Cu-HL(1) and Cu-HSL(1), respectively).

2-(2-Pyridylamino)pyridinium tetra-chlorido-zincate(II).

The structure of the title compound, (C(10)H(10)N(3))(2)[ZnCl(4)], is composed of C(10)H(9)N(3)H(+) (DPAH(+)) cations and [ZnCl(4)](2-) anions. The two pyridyl rings of DPAH(+) are approximately coplanar, with a dihedral angle of 7.2 (2)° between their corresponding least-squares planes. The proton is disordered in a one-to-one ratio over the two chemically equivalent pyridyl N atoms. An intra-molecular hydrogen bond is formed between the pyridinium H atom and the pyridyl N atom of the other pyridyl ring. The Zn atom lies on a twofold rotation axis. There are also some weak N-H⋯Cl hydrogen bonds. These inter-actions lead to the formation of an alternating zigzag chain in the solid state. The results clearly show that reducing agents normally used in hydro-thermal syntheses, such as metallic zinc employed here, are also active in terms of coordination chemistry.

Corrigendum to "Synthesis and Characterization of New Palladium(II) Thiosemicarbazone Complexes and Their Cytotoxic Activity against Various Human Tumor Cell Lines".

[This corrects the article DOI: 10.1155/2013/524701.].

First copper(ii) phase M'0.2Mn0.8PS3·0.25H2O and analogous M' = Co(II), Ni(II) and Zn(II) materials obtained by microwave assisted synthesis.

M'0.2Mn0.8PS3·0.25H2O materials are obtained by a mild microwave assisted reaction (M' = Co(II), Ni(II), Cu(II), Zn(II)), which permitted us to obtain the first copper(ii) bimetallic phase. All these materials have a lower energy gap and antiferromagnetic interactions with lower values of the Weiss constant, than that of the pristine phase MnPS3.