Triclinic P1 Research Articles

Preparation, thermal analyses and biological activities of Co(II) and Cr(III) complexes with 2-acetylpyridine-6-bromo-2-naphthoyl acylhydrazone

Novel six-coordinated octahedral Co(II) complex [C36H26Br2CoN7O5, 1] and Cr(III) complex [C36H26Br2CrN6O2, 2] were prepared by the chelation reaction of the ligand 4-methoxybenzaldehyde-6-bromo-2-naphthoyl acylhydrazone and 2-acetylpyridine with Co(NO3)2·6H2O or CrCl3·6H2O in ethanol, and it is interesting that the coordination organic group wasn't the original acylhydrazone. Based on X-ray single crystal diffraction technique, the structures of 1 and 2 were characterized, which revealed 1 belonged to monoclinic system and P21/n space group, whereas 2 belonged to triclinic system and P1¯ space group. The apparent activation energies of the thermal decomposition of 1 and 2 showed 1 had far better thermal stability than 2. Both of 1 and 2 quenched the intrinsic fluorescence of BSA through static processes, which suggested 1 and 2 could bind to BSA effectively and the non fluorescent ground state complexes were formed. UV–Vis spectra indicated each complex bound to ct-DNA by an intercalative mode. Microcalorimetry experiments illustrated the interactions of two complexes with BSA and ct-DNA were both spontaneous endothermic processes and the binding abilities of 1 with BSA and ct-DNA were greater than that of 2. The minimum inhibitory concentrations (MIC) of each complex against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa were all 50 μg·mL−1.

Construction of lanthanide complexes based on 3,4-dichlorobenzoic acid and 5,5′-dimethyl-2,2′-bipyridine: Supramolecular structures, thermodynamic properties and luminescent behaviors

Two novel lanthanide complexes, [Ln2(3,4-DClBA)6(5,5′-DM-2,2′-bipy)2(C2H5OH)(H2O)] (Ln = Gd(1), Tb(2)); 3,4-DClBA: 3,4-dichlorobenzoate; 5,5′-DM-2,2′-bipy: 5,5′-dimethyl-2,2′-bipyridine) have been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectrum, thermal analysis and single X-ray diffraction techniques. The binuclear complexes 1–2 are isomorphous and crystallize in the triclinic crystal system and P1¯ space group, and each metal center is eight-coordinated with distorted square antiprismatic molecular geometry. The structure of this type of complex is unique in that the solvent ethanol molecule participates in the coordination. Complexes 1–2 are stitched together via π–π stacking interactions and hydrogen bonding interactions to form the 1D, 2D supramolecular structures. The thermal decomposition mechanisms of two complexes were obtained by TG-DSC/FTIR techniques. The molar heat capacities of the complexes 1 and 2 are measured by a DSC instrument over the temperature range from 255.15 to 323.15 K and thermodynamic functions were calculated by fitted polynomial and thermodynamic equations. The luminescence studies demonstrate that complex 2 exhibits the characteristic emission of Tb3+ ion (5D4 → 7F6-3).

Hirshfeld surface analysis of some new heteroleptic Copper(I) complexes

Seven new coordination complexes namely, [Cu(T1) (I) (PPh3)2] (CT1), [Cu(T2) (I) (PPh3)2] (CT2), [Cu(T3) (I) (PPh3)2] (CT3), [Cu(T4) (I) (PPh3)2] (CT4), [Cu(T5) (I) (PPh3)2] (CT5), [Cu(T6) (I) (PPh3)2] (CT6) and [Cu(T7) (I) (PPh3)2] (CT7), were synthesized and characterized by using spectroscopic and crystallographic methods. The results from spectroscopic data and crystal structure analysis showed that in all complexes, the acylthiourea ligands coordinated as monodentate S-donor mode. All of the complexes displayed distorted tetrahedral geometry with one iodide anion, two triphenylphosphine ligands and one acylthiourea ligand (N-benzoyl-N′-(substituted phenyl)thiourea bearing different ortho/meta-substituents; R–H, 3-Me, 3-OMe, 3-OH, 3-Cl, 2-Me and 2-OMe, T1-T7 respectively) attached to the Cu(I) central metal atom. The acylthiourea ligands behaved as a monodentate S-donor ligand instead of its common O, S-bidentate nature due to the tetrahedrally favored geometry of the copper(I) metal and the presence of two bulky group of triphenylphosphine ligand as the co-ligand. Interestingly, CT1-CT4 and CT7 crystals are isostructural and crystallized in the monoclinic P21/c crystal system whereas CT5 and CT6 are also isostructurally crystallized in the triclinic P1¯ crystal system. Isostructural structures of these two crystal systems illustrated almost similar crystal packing but with significantly different interactions as determined by Hirshfeld surface analysis which is discussed herein.

A novel iron (III) organic-inorganic hybrid with a thermochromic transition: Synthesis and structural characterisation of the dicystaminium dichloride aquapentachloridoferrate (III), monohydrate (C4H14N2S2)2[FeCl5(H2O)]Cl2*H2O

The magnetic hybrid material, based on the aquapentachloridoferrate (III), [FeCl5(H2O)]2- and on the dicystaminium cation H2Cys, is reported for the first time in this paper exhibiting an interesting thermochromic behaviour. It was prepared as orange single crystals, suitable for single crystal X-ray diffraction, with the chemical formula (C4H14N2S2)2[FeCl5(H2O)]Cl2*H2O (1). The characterization by X-ray diffraction was carried out at room temperature 296 K and at 120 K. The new derivative displays an asymmetric unit, formed by two H2Cys cations, one anionic complex [FeCl5(H2O)]2- and two Cl−, that ensure the electroneutrality, all trapped in the matrix with one water molecule. It crystallizes in the triclinic P1¯space group with the following unit cell parameter at 120 K and 296 K respectively: a = 10.7913(4) Å, b = 11.4145(5) Å, c = 11.4225(5) Å and α = 99.010(4) °, β = 102.529(4) °, γ = 90.466(3); a = 10.8747(4) Å, b = 11.4717(5) Å, c = 11.5483(4) Å and α = 98.907(3) °, β = 103.169(3) ° γ = 90.635(3). The compound was also characterized by IR spectroscopy and by DSC analysis and its magnetic behaviour was investigated.

Investigation of crystal structure and improved magnetic and dielectric properties of Ti-substituted Bi0.90Ho0.10FeO3 multiferroics

Bi0.90Ho0.10Fe1−xTixO3 multiferroics (with x = 0.00, 0.05, 0.10, and 0.15) were synthesized by method of solid state reaction. The XRD, SEM, dielectric properties, and magnetic measurements of the compounds were carried out. The X-ray patterns show structural change for x = 0.15. Rietveld refinement of the XRD patterns deduces that the samples for x = 0.00, 0.05, and 0.10 are found to fit well with rhombohedral R3c symmetry, while for x = 0.15, sample accomplishes best fitting by the mixed-phase setting of rhombohedral R3c and triclinic P1 space group. The micro-Raman scattering observation also confirms the phase transformation. The change in crystal structure is attributed to the distortion of FeO6 octahedra due to replacing a part of B-site Fe ions by Ti ions. Magnetic measurements were performed at room temperature up to an external magnetic field of ± 10 kOe. Dielectric behaviour of all prepared ceramic samples was carried by impedance/gain phase analyser within the frequency range from 100 Hz to 7 MHz at different temperatures. It was observed that the Ti co-doping shows a significant role for the improving multiferroics properties.

Effect of Ba and Ho co-doping on crystal structure, phase transformation, magnetic properties and dielectric properties of BiFeO3

Multiferroics having composition Bi0.80-xBa0.20HoxFeO3 (BBFO, BBHFO5, BBHFO10, BBHFO15 and BBHFO20 for x = 0.0, 0.05, 0.10, 0.15 and 0.20 respectively) were synthesized by method of solid state reaction. The crystal structure has been studied using X-ray diffraction technique. The X-ray patterns show enormous transform in crystal structure at concentration x = 0.20. The Rietveld refinement of XRD patterns indicates that at concentration x = 0.0 sample have rhombohedral structure with R3c space group while for the concentration x = 0.05, 0.10, 0.15 and 0.20, the mixed phase including rhombohedral R3c and triclinic P1 space groups were obtained with best fitting. This phase transformation in crystal structure is observed due to mismatching of ionic radii of doped ions and parent ions. Magnetic properties of all samples were carried out by using vibrating sample magnetometry. M-H hysteresis loops shows that with doping of Ba and Ho antiferromagnetic BiFeO3 (BFO) transforms into ferromagnetic. The dielectric and ferroelectric measurements were carried out which shows that dielectric constant, dielectric loss and ferroelectric properties are enhanced with co-doping of Ho in comparison of the pristine BFO due to structure deformation and decrease in oxygen vacancies with higher concentration of Ho. Significant improvement has been observed in dielectric constant and remnant magnetization values with increasing content of Ho and decrease in the dielectric loss.

Mononuclear manganese(iii) complexes with reduced imino nitroxide radicals by single-electron transfer and intermolecular hydrogen bonds as an intramolecular structural driving force.

Manganese(iii) complexes were synthesized by one-electron transfer from a Mn(ii) ion to the imino nitroxide radical 2-(2-imidazolyl)-4,4,5,5-tetramethylimidazoline-1-oxyl (IMImH) in methanol. After the manganese ions attained the +III oxidation state, the imino nitroxide radicals were found to be irreversibly reduced in the complexes. Depending on the synthesis conditions, two complexes differing by their counter-anions were isolated as single crystals. These are [Mn(IMHIm)2(MeOH)2]ClO4·H2O (1) and [Mn(IMHIm)2(MeOH)2]PF6 (2), which crystallize in the monoclinic P21/n and triclinic P1[combining macron] space groups, respectively. The two complexes show Jahn-Teller distortions typical of Mn(iii) centres and only reduced radicals are coordinated, as indicated by the N-O bond lengths and electroneutrality. In addition, the crystal structure analyses reveal two intermolecular hydrogen bonding networks. One involves counter-anions, water molecules and reduced radicals, and the other involves coordinated methanol molecules and imidazole moieties. These intermolecular interactions are driving forces that stabilize the two complexes. They also suggest that the tautomer is in the amino imine-oxide form after reduction of the radical and reveal the deprotonation of the imidazole ring, which is required for electroneutrality. This assessment is supported by single-crystal X-ray diffraction, EPR and Raman spectroscopy as well as magnetic and electrochemical studies.

Synthesis, X-ray structure, physicochemical properties and anticancer activity of mer and fac Ru(iii) triphenylphosphine complexes with a benzothiazole derivative as a co-ligand.

Two mononuclear ruthenium(iii) mer- and fac-isomers of the formula [RuCl3(PPh3)(dmpbt)] (where PPh3 = triphenylphosphine, dmpbt = 2-(3,5-dimethylpyrazoll-yl)benzothiazole) have been synthesised from the reaction of [RuCl3(PPh3)3] with a bidentate ligand - dmpbt. Appropriate reaction conditions allowed obtaining the two isomers separately without separation techniques. X-ray crystallography has determined the crystal and molecular structures of the new complexes. mer-Ru(iii) (1) crystallised in the monoclinic P2(1)/n group, and fac-Ru(iii) (2, 2') in the triclinic P1[combining macron] space group. The composition of the ruthenium coordination sphere was confirmed and characterised using spectroscopic techniques (FT-IR, UV-vis and EPR), elemental analysis and mass spectrometry (MS-FAB). The structures of the complexes obtained were analysed using X-ray and other spectroscopic methods (IR and UV-vis). The electrochemical properties of the ligand and the complex compound were identified using cyclic voltammetry, determining the potential and charge of faradaic processes. Both isomers are redox active and display quasi-reversible metal centered redox processes for the Ru(iii)/Ru(ii) pair. Moreover, preliminary tests of their biological activity were performed. The cytotoxicity of these compounds has been tested for human lung carcinoma (A549), chronic myelogenous leukemia (K562), human cervix carcinoma (HeLa) cells, acute lymphoblastic leukemia (MOLT-4), human breast adenocarcinoma cell line (MCF-7) and normal human umbilical vein endothelial cells (HUVEC). The ability to induce apoptosis has been demonstrated in caspase 3/7 activity assay. In addition, the lipophilicity of both isomers was described by a partition coefficient, log P, values of which were estimated by the shake-flask method. The interesting and promising preliminary results of the biological and chemical activities of the new octahedral mer/fac Ru(iii) complexes motivate further in vitro and in vivo studies.

Synthesis, crystal structure and cytotoxicity assays of a copper(II) nitrate complex with a tridentate ONO acylhydrazone ligand. Spectroscopic and theoretical studies of the complex and its ligand

The new copper complex, [Cu(HL)(OH2)2](NO3), including the tridentate N-acyhydrazone derived from 4-hydroxy-benzohydrazide and 2-hydroxy-3-methoxybenzaldehyde, (H2L), has been synthesized and characterized in the solid state and in solution by spectroscopic (FTIR, Ra, UV–vis, EPR) methods. The results were compared with those obtained for the hydrazone ligand and complemented with computational methods based on DFT. The crystal structure of the complex has been determined by X-ray diffraction. It crystallizes in the triclinic P1¯ space group with Z = 2. The Cu(II) ion is in a distorted square pyramidal environment, coordinated to a planar HL- anion acting as a tridentate ligand. The 5-fold coordination is completed with two water molecules. It is arranged in the lattice as H-bonded ribbon-like polymers that extends along the [1 2 1] crystal direction. The cytotoxicity of the complex together with that of the H2L ligand and the copper ion were evaluated in vitro against five different human cancer cell lines namely A549 (lung), MG-63 (bone), MCF-7 and MDA-MB-231 (breast) and Jurkat (leukemia). The copper complex inhibits the cell viability in a dose dependent manner with a greater potency than the H2L ligand and the free copper ion displaying even higher antitumor activity than the well-known anticancer metallodrug cisplatin.

Iron-doping as an effective strategy to enhance supercapacitive properties of nickel molybdate

Iron-doped hydrated nickel molybdate (FexNi1-xMoO4.0.75H2O, x = 0–0.10) nanorods were successfully synthesized via a simple one-pot hydrothermal route. Our investigations showed that hydrated nickel molybdate (HNMO) possesses identical crystal structure to CoMoO4.0.75H2O with a triclinic crystal structure and P1¯ space group. Electron microscopy studies showed that the HNMO powders consist of single crystalline nanorods with [12¯2] growth direction. The effectiveness of iron-doping into the crystalline lattice of the HNMO was demonstrated by powder x-ray diffraction (PXRD), UV–visible spectroscopy and electrochemical impedance spectroscopy (EIS). Upon iron-doping, the band gap energy values reduced from 4.03 eV for the un-doped powder to 3.48 eV for 10 at.% iron-doped HNMO. Electrochemical performance of the nanorods was characterized by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and EIS. The electrochemical properties along the optical data demonstrate that there is a direct relation between the electrochemical performance and the level of iron-doping due to improvement of electrical conductivity. A specific capacitance of 718 F/g related to the HNMO was improved by 47%–1057 F/g upon 10 at.% iron-doping.

Superconductivity at 3.5 K and/or 7.2 K in potassium-doped triphenylbismuth.

We develop a two-step synthesis method-ultrasound treatment and low temperature annealing to explore superconductivity in potassium-doped triphenylbismuth, which is composed of one bismuth atom and three phenyl rings. The combination of dc and ac magnetic measurements reveals that one hundred percent of synthesized samples exhibit superconductivity at 3.5 K and/or 7.2 K at ambient pressure. The magnetization hysteresis loops provide a strong piece of evidence of type-II superconductors. It is found that the doped materials crystallize into the triclinic P1 structure, with a mole ratio of 4:1 between potassium and triphenylbismuth. Both the calculated electronic structure and measured Raman spectra indicate that superconductivity is realized by transferring electrons from the K-4s to C-2p orbital. Our study opens an encouraging window for the search of organic superconductors in organometallic molecules.

Variation of crystal structure, magnetization, and dielectric properties of Nd and Ba co‐doped BiFeO3multiferroics

AbstractMultiferroics having composition Bi0.80Nd0.20‐xBaxFeO3were prepared to investigate the effect of doping on crystal structure, magnetic, and dielectric properties. The Rietveld refinement deduces the formation of mixed structural symmetry. With larger content of Nd, crystal structure consisting of major rhombohedral R3c and minor orthorhombic Pnma has been accomplished. The fraction of rhombohedral phase has been found to increase with doping of Ba up tox= 0.10. At compositionx= 0.15, the orthorhombic phase Pnma disappears, and there is evolution of triclinic phase P1 in place of it. The mixed structure now accomplished contains ≈61% rhombohedral R3c and rest 39% triclinic P1. In solely Ba‐doped sample (ie, atx= 0.20), the fraction of rhombohedral R3c phase again rises and attains ≈92% fraction of the structure along with rest triclinic P1 phase. The M‐H loops depict enormous enhancement in magnetic properties with increasing doping of Ba. Dielectric constant (ε′) and dielectric loss (tanδ) both were found to increase with doping of Ba. The anomalies present in the dielectric constant and dielectric loss with temperature may be regarded to the hopping conduction of e−between Fe3+and Fe2+and their interaction with oxygen vacancies.

The crystal and molecular structure of C.I.Pigment Yellow 155, a high performance bisacetoacetarylide disazo yellow pigment

C.I.Pigment Yellow 155 (Y 155) is an important bisacetoacetarylide disazo yellow pigment with a unique structure, which has the potential to be an alternative for benzidine yellow pigments due to its superior solvent resistance and light fastness. It is essential to investigate the crystal structure of Y 155 to understand the relationship between the structure and technical performance. Y 155 crystallizes in the triclinic P1(—) space group. The molecule exists in the bisketohydrazone form which is consistent with that of disazoacetoacetanilide pigments (Diarylide Yellows). Different from the unsubstituted analogue (BADA), Y 155 molecules are approximately planar due to stronger intramolecular hydrogen bonding. In Y 155 crystals, each molecule is interleaved in two adjacent layers above and below. The color and the technical performance are discussed in relation to its crystal structure especially involving in the role of four methyl formate groups.

A zwitterionic Zn(II) benzothiazole nanohybrid conjugate as hydrolytic DNA cleavage agent

An organic–inorganic hybrid Zn(II) complex has been synthesized in a “zwitterionic” form which crystallizes in triclinic P1 space group possessing labile apical chlorine atoms. DNA interaction studies were performed to enunciate the binding strength. The hydrolytic cleavage potential of the complex was substantiated and the kinetic aspects of the mechanism followed are also discussed.

Investigation of Polymorphism and Vibrational Properties of MnMoO4Microcrystals Prepared by a Hydrothermal Process

MnMoO4 microcrystals were synthesized by hydrothermal methods, and their structural, morphological, and vibrational properties were investigated. Conventional reactors and microwave-heated hydrothermal vessels were used to synthesize micrometer-sized MnMoO4 polymorphs at different temperature and time conditions. MnMoO4·H2O crystals were obtained in both reactors at temperatures below 200 °C, for times up to 24 h. These microcrystals belong to the triclinic P1 space group, and their 26 characteristic Raman bands were identified. A monoclinic MnMoO4 polymorph belonging to the P2/c structure was synthesized at temperatures higher than 200 °C only into conventional hydrothermal reactors. Polarized micro-Raman analyses have evidenced and allowed the assignment of 18 phonon modes predicted by group-theory calculations for this polymorph. Another MnMoO4 polymorph, within the monoclinic C2/m space group, was obtained by two processing routes: (i) heating the P2/c microcrystals at 600 °C; or (ii) heating the MnM...

Cation order in the crystal structure of ‘minasgeraisite-(Y)’

AbstractThe crystal structure of ‘minasgeraisite-(Y)’, triclinic P1, a = 9.994(4), b = 7.705(3), c = 4.764(2) Å, α = 90.042(9), β = 90.218(14), γ = 90.034(9) (°), V = 366.8(5) Å3 and Z = 1, has been refined to an R1 index of 2.86% for 4170 observed (|Fo| > 4σF) reflections. Significant observed (|Fo| > 40–60 σF) reflections violate the presence of a 21-screw axis and an a-glide plane, negating the space group P21/a previously found for minerals of the gadolinite–datolite group. Averaging of the X-ray data in Laue groups 2/m and $\bar 1$ gives the following agreement indices: 2/m (9.68%) and $\bar 1$ (5.68%). The internal agreement index from averaging of identical reflections collected at multiple positions along the diffraction vector is significantly lower than that for the Laue group $\bar 1$: Rpsi = 2.40%, where 13,109 reflections were collected, 4288 are unique for P1 symmetry, and Rpsi is based on a mean data redundancy factor of > 3. Both the data merging and an |E2–1| value of 0.773 indicate that P1 is the correct space group. The general formula for the gadolinite–datolite group is W2XZ2T2O8V2 (Z = 2) which we have expanded to 20 anions (Z = 1) to show the W-site cation ordering present in ‘minasgeraisite-(Y)’. Bismuth, Ca and REE are ordered over four W sites, with Bi dominant at W1, Ca dominant at W2, and Y dominant at W3 and W4. The dominant constituent at the X sites is a vacancy, and Ca does not occur at the X sites. Significant B and Si are assigned to the Be-dominant Z sites, and the T sites are occupied by Si. The simplified ‘minasgeraisite-(Y)’ formula (Z = 1) is BiCa(Y,Ln)2(□,Mn)2(Be,B,Si)4Si4O16 [(OH),O]4. ‘Minasgeraisite-(Y)’ should be assigned to a triclinic subgroup of the gadolinite–datolite group, and its lower symmetry suggests that Ca-substituted gadolinites and hingganites should be examined for evidence of triclinic symmetry associated with cation order at the W sites.

Synthesis, structural studies and antimicrobial activity of N'-((2Z, 3E)-3-(hydroxyimino)butan-2-ylidene)-2-phenylacetohydrazide and its Co(II), Ni(II) complexes

A new aroylhydrazoneoxime, N'-((2Z, 3E)-3-(hydroxyimino)butan-2-ylidene)-2-phenylacetohydrazide ligand (LH2) and its Ni(II) and Co(II) complexes, have been synthesized and characterized by elemental and thermal analyses, IR and UV–vis spectroscopy, magnetic moment and X-ray diffraction. The antimicrobial activities of these compounds were tested by using minimal inhibitory concentration method (MIC). The ligand-containing aroylhydrazone and oxime groups and its Ni complex crystallize in the triclinic system and P1− space group, while its Co complex crystallizes in the monoclinic system and the C 2/c space group. X-ray results show that the ligand in the keto form is transformed into enolic form when it forms coordination. From elemental analysis data, the stoichiometry of Co(II) complex was found to be 1:2 (metal/ligand), but 1:1 for Ni(II). IR spectra indicate that the ligand acts as monoanionic NNO− tridentate and coordination takes place form through the oxime nitrogen, imine nitrogen, and enolate oxygen atoms.

Doping effect on ferromagnetism, ferroelectricity and dielectric constant in sol-gel derived Bi1−xNdxFe1−yCoyO3 nanoceramics

Doping at the post-transition metal site by trivalent rare-earth ions and 3d transition metal site by transition metal ions in perovskite lattice has observed a variety of magnetic and electronic orders with spatially correlated charge, spin and orbital degrees of freedom. Here, we report large ferromagnetism and enhanced dielectric constant (at ∼100 Hz) in chemically synthesized single phase multiferroic Bi1−xNdxFe1−yCoyO3 (x = 0, 0.10; y = 0, 0.10) nanoparticles (average particles size ∼45 nm). We have also examined the ferroelectric nature of our chemically synthesized samples. The Rietveld refinement of the XRD data reveals the structural symmetry breaking from distorted rhombohedral R3c structure of BiFeO3 to the triclinic P1 structure in Bi0.9Nd0.1Fe0.9Co0.1O3 (BNFCO) without having any iron rich impurity phase. The magnetization in these nanoceramics most likely originates from the coexistence of mixed valence states of Fe ion (Fe2+ and Fe3+). A high room temperature dielectric constant (∼1050) has been observed at 100 Hz of BNFCO sample. The frequency dependent anomalies near Neel temperature of antiferromagnet in temperature variation of dielectric study have been observed for all the doped and co-doped samples exhibiting typical characteristic of relaxor ferroelectrics. A spectacular enhancement of remanent magnetization MR (∼7.2 emu/gm) and noticeably large coercivity HC (∼17.4 kOe) at 5 K have been observed in this BNFCO sample. Such emergence of ferromagnetic ordering indicates the canting of the surface spins at the surface boundaries because of the reduction of particle size in nanodimension. We have also observed P-E hysteresis loops with a remanent polarization of 26 μC/cm2 and coercive field of 5.6 kV/cm of this sample at room temperature. From impedance spectroscopy study the estimated activation energy of 0.41 eV suggests the semiconducting nature of our nanoceramic BNCFO sample.

Organic-inorganic hybrid crystals, (2,4,6-CH3PyH)3Sb2Cl9 and (2,4,6-CH3PyH)3Bi2Cl9. Crystal structure characterization and tunneling of CH3 groups studied by 1H NMR and neutron spectroscopy

The crystal structures of (2,4,6-CH3PyH)3Sb2Cl9 (TMPCA) and (2,4,6-CH3PyH)3Bi2Cl9 (TMPCB) (Py – pyridine) have been determined at 100 K by the single crystal X-ray diffraction method. TMPCA and TMPCB crystallize in the monoclinic C2/c and triclinic P1 polar space group, respectively. In both cases the asymmetric part is comprised of three nonequivalent 2,4,6-trimethylpyridinium cations and a discrete M2Cl93− anion. The Bi2Cl93− moiety forms a face-sharing bi-octahedron, whereas in a case of Sb2Cl93− we deal with two pyramids connected by a corner. The inelastic neutron scattering spectra (INS) were recorded for TMPCA at low temperatures (4–50 K). Two peaks on each side of the central elastic line have been observed at ca. 4.8 and 2.9 μeV, the high energy peak exhibits an excitation energy value equal to ca. 6 meV. For TMPCA and TMPCB the 1H NMR spin–lattice relaxation times, T1, have been measured in the temperature region 15–410 K. The flattening of the T1 (spin–lattice) vs. reciprocal temperature, 1/T, dependence between 30 K and 15 K indicates the incoherent tunneling effect of the methyl group being treated as the quantum rotor. The conclusions drawn from the 1H NMR results as regards to the tunneling of the CH3 groups in the pyridinium cations are consistent with the tunneling peaks observed in the INS spectra.

Tri- (M = CuII) and hexanuclear (M = NiII, CoII) heterometallic coordination compounds with ferrocene monocarboxylate ligands: Solid-state structures and thermogravimetric, electrochemical and magnetic properties

The synthesis and characterization of the hexanuclear [M2(κO-O2CFc)2(µ-O2CFc)2(µ-H2O)(κ2N,N′-tmeda)2] (MII=Ni, 5; Co, 6; Fc=ferrocenyl, (η5-C5H4)(η5-C5H5)Fe; tmeda=N,N,N′,N′-tetramethylethylendiamine) and the trinuclear [Cu(κ2N,N′-tmeda)(κ2O,O′-O2CFc)2 2] (7) coordination compounds are described. Compounds 5–7 were prepared by the consecutive reaction of ferrocene carboxylic acid (FcCO2H; 1) with [nBu4N]OH followed by treatment of in situ formed [nBu4N][FcCO2] with the metal salts [M(tmeda)(NO3)2] (M=Ni, 2; Co, 3; Cu, 4). The structures of 5–7 in the solid state were determined by single crystal X-ray diffraction analysis. Isostructural 5 and 6 crystallise in the triclinic P1¯ (5) and in the monoclinic space group P21/n (6). The two MII(tmeda) entities of 5 and 6 with MII=Ni, Co, respectively, are syn, syn-bridged by two FcCO2− functionalities and one µ-bridging water molecule. Additionally, two FcCO2− ligands are κO-coordinated to each MII ion to form octahedral MN2O4 coordination setups. A related MN2O4 coordination setup is observed for 7 as well, whereby the CuII ion is coordinated by two O2CFc and one tmeda ligand. Electrochemical investigations reveal that all individual Fc units of 5–7 are oxidized separately. Thermogravimetric analysis showed that 5 and 6 start to decompose at 110 and 125°C and thus at significantly lower temperatures compared to 7 (200°C). The mass residues obtained after decomposition are composed of Fe2O3, FeNi3 and Fe0.64Ni=Ni0.36 (5), Fe and Co3O4 (6) and Cu2O and CuFeO2 (7), as determined by powder X-ray diffraction analysis (PXRD). Thermal susceptibility measurements of 5 and 6 determined a weak antiferromagnetic coupling in 5 and 6 with J=1.1K and J=1.9K, respectively.