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Two novel semiconducting coordination oligomers with 1D chain structures, namely [H0.07 CuI0.65CuII0.14(μ-p-CNC6H4CO2)·0.9H2O]n and [Ag(μ-p-CNC6H4CO2)]n, were obtained and characterized by XRD powder patterns, and XPS, EPR, UV-vis-NIR, IR and Raman spectroscopy. According to XRD analysis, CuICuII–ICNBA is an amorphous solid, while AgI–ICNBA crystalizes with a monoclinic unit cell in the C2/c space group (Z = 4). The composition and further information of CuICuII–ICNBA were obtained from the spectroscopic data. In correspondence with the quantification of terminal groups from high-resolution XPS spectra, CuICuII–ICNBA and AgI–ICNBA are composed of an average of 9 and 7 monomer units, respectively, resulting in 1D-oligomers. The spectroscopic evidence indicates that CuICuII–ICNBA is better described as a non-stoichiometric coordination oligomer (where non-integer ratios of metal ions can be accommodated), while AgI–ICNBA is stoichiometric. In both materials, each metal center is linked by two μ-η1:η1-p-isocyanobenzoate ligands forming microfibers of around 120 nm (CuICuII-material) and 310 nm (AgI-material) in average diameters with optical band gaps of 2.60 eV and 2.17 eV, respectively.

In the present manuscript, we report the kinetic and spectroscopic analysis of six new pinch-porphyrins: protoporphyrin-picpenta 1, mesoporphyrin-picpenta 2, deuteroporphyrin-picpenta 3, protoporphyrin-picocta 4, mesoporphyrin-picocta 5, and deuteroporphyrin-picocta 6. The Michaelis–Menten enzymatic pathway and the guaiacol test confirmed the ability of the compounds to function like new peroxidase models. UV–vis, 1H NMR, and electron spin resonance studies are in accordance with porphyrin-Fe(III) molecules with the quantum phenomena called quantum mixed spin (qms, s = 3/2, s = 5/2). Importantly, the influence of the presence of the s = 3/2 spin state in the compounds and its critical role for the catalytic capacity is proven here, which was the original hypothesis in our research group. The compounds with higher populations of the s = 3/2 spin state have increased peroxidase activity.

In this work we report the synthesis, structural, electronic and magnetic characterization of [MnIV2MnII2(HL)2(H2L)2(H2O)4](NO3)2 1. This novel compound was obtained from (E)-2-((2-hydroxybenzylidene)amine)-2-(hydroximethyl-propane-1,3-diol, (H4L) and Mn(NO3)2. The UV-Vis and IR spectrophotometry showed the typical d-d transitions of MnIV in and octahedral geometry compounds 1 and vibrational transitions in 477 cm-1, which is assigned to the Mn-O group 2. The cM vs T gave J = 164 cm-1 3. The ESR (g = 11.03, 4.87, 1.78, and g = 3.23, 2.03) analysis of 1 showed the presence of MnII (s = 5/2) and MnIV (s = 3/2) ions within the molecule. The hyperfine interaction is observed in ESR spectrum which showed two species of Mn ions4. An x ray diffraction suitable monocristal of 1 was obtained and its structure was possible to describe as a tetramer of [MnIV MnII MnII MnIV] building a 2D stepped supramolecular structure with a step of [MnIV–O-O-MnII] and a second step with [MnII–O-O-MnIV]. The structural study informed us that each magnetic box of [MnIV-O-O-MnII] have a superexchange antiferromagnetic interaction by the dx2-y2-sp3 (with more contribution of p orbitals) orbitals; however, among the boxes or steps there is a super-exchange ferromagnetic interaction, by oxo bonds MnII-O-MnII. Ye T., Li S., Wu X., Xu M., Wei X., Wang K., Bao H., Wang J. and Chen J. J. Mater. Chem. C, 2013, 1, 4327–4333. Lever A. B. P. Inorganic Electronic Spectroscopy. 2a Edition. Elsevier, 1997. Czernuszewicz S. R., Su O. Y., Stern K. M., Macor A. K., Kim D., Groves T. J. and Spiro G. T. Am. Chem. Soc. 1988, 110, 4158-4165. Nakamoto K. Infrared and Raman Spectra of Inorganic and Coordination Compounds. 6a edition, John Wiley & Sons, 2009. Yoo J., Brechin E., Yamaguchi A., Nakano M., Huffman C. J., Maniero L. A., Brunel L. C., Awaga K., Ishimoto H., Christou G. y Hendrickson D. Chem. 2000, 39, 3615-3623. Milios J. C., Piligkos S., Bell R. A., Laye H. R., Teat J. S., Vicente R., McInnes E., Escuer A., Perlepes P. S. y Winpenny P. E. R. Inorganic Chemistry Communications. 2006, 9, 638–641. Ramirez R. D., Zamorano U. R., Perez M. O. Solid State Communications. 2001, 118, 371-376.

In the present work, the hydrotalcite-like materials known as layered double hydroxides (LDHs) were synthesized. The Ni–Al and Ni–Fe materials with different Ni/Fe ratio were obtained by coprecipitation method at variable pH. The LDH structure was verified by X-ray diffraction, Fourier transform infrared, and Raman spectroscopy. No secondary extra phases were observed for any material. The electronic properties were evaluated by UV–vis spectroscopy, while the magnetic ones were followed by electron paramagnetic resonance (EPR). The results suggested that sample H/Ni–Fe2 (Ni/Fe = 2) has a ferrimagnetic behavior as a result of the combined action of NiII–OH–NiII, FeIII–OH–NiII, and FeIII–OH–FeIII pairs across the layers and ferromagnetic interactions operating between layers. Furthermore, the material H/Ni–Fe1 (Ni/Fe = 1.5) showed a combination of paramagnetic and ferromagnetic interactions which favors a superexchange interaction among metal centers through the OH bridges across the cationic sheets; the su...

[Cu(II)(saleanN3H3)] 1 (saleanN3H3 = N,N″-bis(2-oxybenzyl)-diethylenetriamine dianion) is obtained by direct synthesis. 1 crystallizes in orthorhombic space group Pbca. The crystalline network features one-dimensional (1D) columns of zigzag chains well separated in the [1 0 0] direction. Each column is a supramolecular structure, with triangles formed among the Cu(II) ions of the chain. Local Cu(II) geometry in 1 is intermediate between square-pyramidal and trigonal–bipyramidal conformations. UV–Vis spectrum, IR, and NMR 1H spectra prove the formation of 1. X-band ESR spectra at 77 K/300 K of a polycrystalline sample show a broad singlet with temperature independent values g||/g⊥ = 2.1967/2.1074. An area ratio A77/A300 of 1.63 suggests an incomplete antiferromagnetic (AF) coupling of the copper ions. The X-band ESR spectra at 77 K in solution show typical hyperfine interactions of monomer paramagnetic copper ions. The linear chain model fits well the magnetic susceptibility data vs temperature from 2 to 300 K and is consistent with antiferromagnetic exchange interaction.

Synthesis, structural, electronic, and magnetic characterization of two [CuII 2(thb)] (thb = N,N,N’,N’- tetrakis-{3-[(2- hydroxibenzyliden)-amine]propyl}-1,4-butanodiamine)]) crystalline phases (1a and 1b) are reported. Both, 1a and 1b, showed free radical scavenging activity, which was quantified by the DPPH free radical scavenging activity assay. 1b crystallized in a P21/c space group. In 1b each molecule contains two CuII-(hidroxibenzyliden) groups bonded in the extremes of the organic DAB-Am nucleus. The CuII-(hidroxibenzyliden) groups of each extreme, form 1D chains along of the b-axis. IR and UV-Vis spectra showed d-d transitions and νCu-O, νCu-N vibrations respectively, confirming the formation of the compound. 1H-NMR spectra of 1a and 1b showed similar spectra, being characteristics of paramagnetic compounds. Bulk magnetization of 1a and 1b from 2 K to 300 K showed paramagnetic behaviour. The best fit for the susceptibility data was obtained using Curie-Weiss and modified Curie-Weiss equations with θ and C values of θ1a/1b C-W = 0 ± 1K, C1a/1b C-W = 0.82/0.66 cm3 K mol-1, and θ1a/1b modified C-W = 0.6 ± 1K and C1a/1b modified C-W = 0.80/0.70 cm3 K mol-1. The X-band ESR spectra of 1a and 1b in solid samples showed a single and a rhombic signals, respectively, with g values around 2.1 at 77 K and 300 K, however, in CH2Cl2 solutions at 77 K the spectra were similar. The spectroscopic and magnetic results allowed us to conclude that 1a and 1b are two different crystalline phases which were proven to act as effective antioxidants showing both an IC50 = 16.5 μM, in contrast with Trolox, IC50 = 39.3 μM, normally used as a vitamin E analog and a strong antioxidant. Additionaly the DPPH free radical is scavened by reduction mechanism of CuII to CuI. The overall electronic, magnetic and structural information about 1a and 1b provide us some characteristics of this kind of transitional metal ionic coordination compounds.

The synthesis, structural, electronic and magnetic characterization of five dinuclear Co(II) azacryptand compounds (1-5) bridged through different ions are reported. The magnetic exchange interactions, 2J values, obtained from theoretical computations show that the variation of the intermetallic angles and distances lead to antiferromagnetic behaviours. Magneto-structural correlations show a trend, where the angles Co(II)-bridge-Co(II) closer to 180 degrees favour an increase in the superexchange pathway leading to higher AF interaction values.

Complex [Cu(II)(Br)(PhCO2)(Sp)] 1 is obtained starting from copper(0), (−)-sparteine (sp) and benzoyl bromide. 1 Crystallizes in the monoclinic space group P21 with a=14.8857(11), b=8.9257(9), c=17.4456(14) A, β=111.689(5)°, and Z=4. The UV–vis spectrum is characteristic of Cu(II) complexes with tetragonally distorted square pyramidal geometry. The far IR spectrum of 1 shows characteristic vibrations of Cu–Br (239 cm−1), Cu–N (437 cm−1) and Cu–O (466 cm−1) bonds. The 1H NMR broad chemical shifts of 1 integrated for a total of 31 protons and are typical of Cu(II) complexes. ESR spectra of polycrystalline 1 at 77 and 300 K show axial spectra with areas in the ratio A77/A300=4.02, suggesting a very weak Cu–Cu ferromagnetic interaction. Complex 1-doped with Zn(II) gives hfs with hyperfine interaction constant value A∥=112.45×10−4 cm−1. The magnetization vs temperature data in the 2–299 K range, show that cupric ion pairs interact through a small antiferromagnetic Heisenberg exchange energy—JS1·S2 with a ground singlet state S=0, separated by J=−1.3 cm−1 from the excited triplet state S=1. The sign of the very weak interchange interaction constant, J, does not agree with the ESR spectra areas ratio of 1 at 77 and 300 K, which is a more accurate quantification of the weak ferromagnetic interaction Cu–Cu through the space.

New complexes of the pinch-porphyrin family were obtained from the dimethylester of (proto-, meso-, and deutero-porphyrinato)iron(III) with the ligand [N,N'-bis-pyridin-2-ylmethyl-propane-1,3-diamine] 1-3 and with the ligand [N-pyridin-2-ylmethyl-N'-[3-[(pyridin-2-ylmethyl)-amino]-propyl]-propane-1,3-diamine] 4-6. The UV/VIS studies of 1-6 indicate an increase in the distortion of the ligand field excited state. The 1H NMR spectra of 1-6 at RT and over the range 223-328 K show iron(III)-complexes with quantum mixed spin state (qms) S=5/2, S=3/2. The chemical shifts of the meso protons are consistent with qms state S=3/2, S=5/2, where the S=3/2 spin state is lowest in energy. For methyl-heme the chemical shifts are also consistent with a qms state but now the S=5/2 ground state is lowest in energy. ESR spectra of 1-6 show two different species, B and C, of iron(III) with qms, S=5/2, S=3/2 consistent with the 1H NMR results. Species B with 70% of S=5/2 and species C with 72.5% of S=3/2. The catalytic activity as peroxidase of 1-6 was quantified by guaiacol test; their theoretical maximum rate constants were k(cat) approximately 10(2)-10(3) M(-1) s(-1). A quantitative empirical correlation is found: the higher the 32 spin contribution to the qms state and the higher proportion of this species into the samples, the higher the peroxidase activity. Such a correlation was also obtained for pinch-porphyrins already reported.

[((−)-Sparteine)(PhCO 2 )(Cl)]Cu(II) 1 complex is obtained by direct synthesis using copper(0). 1 crystallizes in the monoclinic space group P 2 1 with a =14.7355(12), b =8.9768(5), c=17.2810(10) A , β =111.916(5)°, and Z =4. The electronic spectrum of 1 shows a broad band with λ max ∼841 nm (e=0.261 mM −1 cm −6 ) characteristic of a low symmetry and tetragonally distorted square pyramidal local Cu geometry. The far IR spectrum of 1 shows characteristic vibrations of Cu–Cl (260, 267 cm −1 ), Cu–N (436, 467 cm −1 ) and Cu–O (457 cm −1 ) bonds. The 1 H NMR spectrum of 1 is typical of magnetic Cu(II) complexes with line broadening due to efficient nuclear relaxation from the metal center. ESR spectra of polycrystalline 1 at 77 K show an axial spectrum with linewidth of 58.6 G and at 300 K of 89.0 G, with areas in the ratio A 77 / A 300 =2.79, indicative of antiferromagnetic order. The linewidth is reduced by 34% on going from 300 to 77 K. Standard magnetization measurements at low temperatures show an Curie–Weiss behavior with θ=−21.67 K , suggesting a weak exchange coupling interaction. The crystalline structure of 1 shows that the lattice is arranged so that the space between molecules is smaller than 40 A 3 , not enough to accommodate solvent molecules. However, the shortest Cu–Cu contact is 7.5912(8) A.

[CuL]Cl·H2O 1 (L=N-glycyl-2(aminomethyl)benzimidazol) compound crystallizes in the orthorhombic space group Pna21 with unit cell parameters a=7.140(5) A , b=17.621(5) A , c=9.941(5) A . Its structure shows that the copper(II) ion is tetra coordinated with a square planar geometry. The ligand acts as a tridentate and the chloride ion is the fourth ligand. Symmetry related units stack into helicoidal columns along the ā direction producing weakly bonded strips with dihedral angles of 2.6° between two consecutive molecular planes. UV/VIS spectrum of 1 shows one broad and weak band at 622 nm, characteristic of d–d transitions, indicative of low local Cu(II) symmetry. X band ESR spectra of 1 at 300 and 77 K are axial exchange narrow lines with g∥=2.135 and g⊥=2.028. However, the axial spectrum at 6.4 K shows an increment Δg∥=0.076(6) and Δg⊥=0.028(4) which suggests a cooperative Jahn–Teller interactions between complexes via the hydrogen-bonding network. Magnetic susceptibility data at 18–300 K and fitted to the modified Bleany–Bowers equation indicate a weak ferromagnetic coupling with 2J≅+17 cm −1 , which is compatible with the helium temperature ESR results and with the helicoidal stacking into columns of the molecules along the a-axis with 78.9° Cu′–Cl′–Cu and 81.2° Cu′–N(1)–Cu bonds angles. The synthesis is a novel, simple and efficient method: in aqueous conditions and heterogeneous phase with basic copper(II) carbonate, which carries out the formation of the stable peptide bond.

Electron spin resonance (ESR) studies of the Pb0.88Eu0.08 Ti1−yMnyO3 (y=0.0, 0.1, 0.2, 0.3); PbTi0.98Mn0.02O3 and PbTiO3 ferroelectric ceramics are reported. The conversion of Mn4+ to Mn2+ in the Pb0.88Eu0.08Ti1−yMnyO3 ceramics compositions have been clearly demonstrated. The presence of the Eu cation is necessary for such conversion to take place and it does not take place in the PbTi0.98Mn0.02O3 ceramic. Analysis of its ESR spectra indicates that Mn4+ substitution occurs at the Ti4+ at two different ESR-distinguishable locations. Both factors, namely the Mn4+→Mn2+ conversion and the Eu3+ presence are responsible for the large microstrain and the deterioration of crystallinity observed in this ceramics, which seemed to play a crucial role for reading large piezoelectric anisotropy in the system.

The novel complexes [1,9-bis(2-pyridyl)-2,5,8-triazanonane]-(protoporphyrinato)iron(III) 4, -(mesoporphyrinato)iron(III) 5 and -(deuteroporphyrinato)iron(III) 6 were synthesized from the parent compounds chloro-(porphyrinato)iron(III) 1, -(mesoporphyrinato)iron(III) 2 and -(deuteroporphyrinato)iron(III) 3 and 1,9-bis(2-pyridyl)-2,5,8-triazanonane (picdien). The complexes 1–6 were characterized by UV/VIS, 1H NMR and ESR spectroscopies and their catalytic activity was determined. The measured theoretical maximum rate constant (kcat) for guaiacol + H2O2 → oxidation guaiacol products (guaiacol = 2-methoxyphenol) in the presence of complexes 4–6, were 7.6 × 106, 4.4 × 105 and 9.0 × 104 mol–1 s–1, respectively. These peroxidase activities are to our knowledge the largest reported for model complexes. The UV/VIS spectra show Soret and Q bands for all compounds at energies typical of axially co-ordinated complexes with symmetry D4h or lower. The intensity of the charge-transfer transitions indicates that the presence of the picdien ligand diminishes the distortion of the parent compounds. The 1H NMR spectra of complexes 4–6 are indicative of six-co-ordinated complexes with different degrees of quantum mixed-spin (qms) state S = into S = . The ESR spectral features are characteristic of qms species, A and B, for each compound. Maltempo’s theory for qms states gives the admixture percentage of species A (53–64%) and species B (

The molecular and crystal structure of the complex [MnL(H2O)2]Cl2·4H2O 1 (L = 2,13-dimethyl-3,6,9,12,18-pentaazabicyclo[12.3.1]octadeca-1(18),2,12,14,16-pentaene) have been determined, the solid state and solution electronic spectra recorded and the thermogravimetric analysis as well as an ESR analysis at different temperatures performed. The structure shows that the cation displays a distorted pentagonal-bipyrimidal co-ordinated geometry, with the macrocycle in the pentagonal plane and two water molecules in the axial positions. From the UV/VIS spectra it can be seen that the electronic structure of 1 is very sensitive to surroundings. The 300 K ESR spectrum of 1 consists of five fine-structure lines centred at g = 2.111, showing anisotropy. A sequence of spectra neatly shows that the compound has a clear magnetic dependence on temperature. Spectral analysis and theoretical calculations give the best 300 K zero-field splitting parameters as D = 0.07 cm–1, E = 0.008 cm–1, λ = E/D = 0.1142. The 77 K zero-field splitting parameters increase to D = 0.074 cm–1 and E = 0.012 cm–1, thus indicating an increasing rhombic distortion as the temperature decreases. The Q-band spectra at 300 and at 77 K are isotropic, and the zero-field effects are very small. The theoretical Q-band spectra were calculated on the basis of the X-band parameters. The temperature variation of the crystal-field parameters is interpreted as a smooth magnetostructural temperature dependence of the compound.

A new crystalline polymorphic phase of tetrakis(mu2-benzoato-O,O')-bis(dimethyl sulfoxide)dicopper(II) was obtained by direct synthesis, in space group P2(1)/n. The copper coordination is in a slightly distorted square pyramidal geometry with an intramolecular Cu...Cu distance of 2.6494(8) angstroms. The Cu-O distances of the two copper in a dimer are different, giving different chemical environments for each Cu ion. The crystal structure is built up of well-separated stacking columns oriented along the b-axis, with units uniformly spaced, producing a one-dimensional (1-D) zigzag chain through Cu(II)-S...S-Cu(II) interdimer interactions [S...S separation: 3.975(2) angstroms]. Magnetization measurements in the range 2-300 K indicate two magnetic orderings, at low temperature (T10 K) a weak ferromagnetic ordering is observed, and above this temperature an antiferromagnetic behavior takes place. ESR spectra at 300 and 77 K of a polycrystalline sample show the characteristic signal of zero-field with D = 0.354 cm(-1), consistent with a ferromagnetic Cu...Cu exchange interaction at low temperature.