Synthesis and Characterization of a Displacement-Type Ferroelectric-Ferroelectric Phase Transition Compound [(NH3)(CH2)3(NH3)]2[InBr6]Br·H2O.

Ferroelectric materials have aroused the researchers' great interest due to their wide applications. Here, a displacement-type ferroelectric-ferroelectric phase transition material [(NH3)(CH2)3(NH3)]2[InBr6]Br·H2O (1) with Tc = 143 K was successfully prepared. The ferroelectric phase transition is verified by the characterization techniques such as differential scanning calorimetry, single-crystal structure elucidation, dielectric and ferroelectric measurements. The single-crystal structure elucidation reveals that the displacement and distortion of [(NH3)(CH2)3(NH3)]2+ cations lead to the phase transition from Cmc21 to Pca21. The spontaneous polarizations at 293 and 133 K are 0.15 and 0.12 µC·cm-2, respectively. We expect that this work will help in further exploration of some new ferroelectric materials.

Two In-based organic-inorganic hybrid compounds with reversible phase transition derived from the order-disorder changes of cations or anions.

Solid-state phase transition materials have received extraordinary interest due to their rich physical properties, such as thermal, dielectric, and ferroelectric properties. Here, two In-based organic-inorganic hybrid compounds, (C6H5CH2CH2NH3)3[InBr5(H2O)] (1) and [(C3H7)4N][InCl4] (2), both display reversible phase transition and dielectric response. Differential scanning calorimetry measurements indicate that the phase transition temperatures (Tc) of 1 and 2 are 167 K and 351 K, respectively. Moreover, structural analyses disclose that the phase transition of 1 can be attributed to the order-disorder changes of phenethylammonium organic cations whereas the phase transition of 2 is caused by the order-disorder changes of [InCl4]- anions. The phase transitions of In-based organic-inorganic hybrid compounds can be driven by the order-disorder changes of cations or anions. Therefore, the system of In-based organic-inorganic hybrid compounds is very suitable for exploring organic-inorganic hybrid phase transition materials.

Apoptotic effect of novel pyrazolone-based derivative [Cu(PMPP-SAL)(EtOH)] on HeLa cells and its mechanism.

Pyrazolone complexes have strong anti-tumor and antibacterial properties, but the anti-tumor mechanism of pyrazolone-based copper complexes has not been fully understood. In this study, the possible mechanism and the inhibitory effect of a novel pyrazolone-based derivative compound [Cu(PMPP-SAL)(EtOH)] on human cervical cancer cells (HeLa cells) was investigated. [Cu(PMPP-SAL)(EtOH)] effectively inhibited proliferation of HeLa cells in vitro with an IC50 value of 2.082 after treatment for 72 h. Cell cycle analysis showed apoptosis was induced by blocking the cell cycle in the S phase. [Cu(PMPP-SAL)(EtOH)] promoted the loss of mitochondrial membrane potential, release of cytochrome c, PARP cleavage, and activation of caspase-3/9 in HeLa cells. Additionally, [Cu(PMPP-SAL)(EtOH)] inhibited the PI3K/AKT pathway and activated the P38/MAPK, and JNK/MAPK pathways. [Cu(PMPP-SAL)(EtOH)] also inhibited the phosphorylation of Iκ-Bα in the NF-κB pathway activated by TNF-α, thus restricting the proliferation of HeLa cells which were activated by TNF-α. In conclusion, [Cu(PMPP-SAL)(EtOH)] inhibited the growth of HeLa cells and induced apoptosis possibly via the caspase-dependent mitochondria-mediated pathway. These results suggest that [Cu(PMPP-SAL)(EtOH)] can be a potential candidate for the treatment of cervical cancer.

Synthesis and characterization of a new organic-inorganic hybrid ferroelectric: (C4H10N)6[InBr6][InBr4]3·H2O.

Organic-inorganic hybrid ferroelectric materials have attracted attention from researchers as promising candidates for functional materials, because they combine high performance and low cost. Herein, a new organic-inorganic hybrid ferroelectric material (C4H10N)6[InBr6][InBr4]3·H2O (1) was synthesized and characterized. The compound undergoes a paraelectric-ferroelectric phase transition at TC = 232 K, which is investigated by differential scanning calorimetry (DSC), dielectric measurements and variable-temperature structural analyses. Crystal structure analyses indicated that the disorder-order transition of Br atoms in [InBr4]- anions depending on temperature was the main factor driving the phase transition from Pbcn to Pna21. This finding will open up a new direction to probe the organic-inorganic hybrid molecular ferroelectric phase transition materials.

Cobalt and cobalt oxides N-codoped porous carbon derived from metal-organic framework as bifunctional catalyst for oxygen reduction and oxygen evolution reactions.

Metal-organic framework (MOF)-derived transition metal/metal oxide-carbon hybrids are promising cost-effective electrocatalysts to replace noble metal catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Co@CoO@Co3O4-N/C was prepared by two-step thermal treatment of Co-MOF ([Co(INA)2]·0.5EtOH) (INA: isonicotinic acid). Firstly, Co-MOF, as precursor, was pyrolyzed at different temperatures in N2 atmosphere to obtain Co-N/C-T (T = 700, 800, 900 °C) materials among which Co-N/C-800 shows remarkably high ORR activity. After oxidation treatment, Co-N/C-800 is transformed into Co@CoO@Co3O4-N/C which exhibits enhanced electrocatalytic activities for both ORR and OER. The as-obtained Co@CoO@Co3O4-N/C has more positive onset potential (-0.136 V vs. Ag/AgCl) and higher limit current density (4.9 mA cm-2) than Co-N/C-800 (-0.143 V vs. Ag/AgCl and 3.9 mA cm-2), as well as better tolerance to methanol and stability (80.0%) than those of Pt/C (63.2%) for ORR. Co@CoO@Co3O4-N/C also displays outstanding OER performances, with lower overpotential (450 mV) than that of Co-N/C-800 (492 mV) at a current density of 10 mA cm-2. The excellent electrochemical performance of Co@CoO@Co3O4-N/C can be ascribed to uniformly dispersed Co-Nx active sites, strong synergistic effects between N-doped carbon support and Co@CoO@Co3O4 as well as ordered mesoporous structure, boosting mass transfer and accelerating electrocatalytic reaction.

Synthesis, crystal structure and biological activity of two Mn complexes with 4-acyl pyrazolone derivatives.

In order to study the biological activities of transitional metal complexes based on 4-acyl pyrazolone derivatives, two Mn complexes [Mn(HLa)(La)]·(CH3CN)1.5·H2O (1) and [Mn2(Lb)2(µ-EtO)2(EtOH)2] (2) (H2La = N-(1-phenyl-3-methyl-4-benzoyl-5-pyrazolone)-2-thiophenecarboxylic acid hydrazide, H2Lb = N-(1-phenyl-3-methyl-4-propenylidene-5-pyrazolone)-2-thiophenecarboxylic acid hydrazide) have been synthesized and characterized. Single crystal X-ray diffraction analysis indicated that 1 is a mononuclear complex and 2 exhibits a dinuclear centrosymmetric structure. Binding of the complexes with Herring Sperm DNA (HS-DNA) showed that complexes 1 and 2 could intercalate to DNA with quenching constant of 5.3×10(4) M(-1) and 4.9×10(4) M(-1), respectively. The interactions of the complexes with bovine serum albumin (BSA) indicated that complexes 1 and 2 could quench the intrinsic fluorescence of BSA in a static quenching process. Further, the inhibitory effects of the complexes on the cell population growth of the human esophageal cancer Eca-109 cells and the cervical cancer HeLa cells were determined by MTT assay, which indicated that both 1 and 2 significantly inhibited the growth of Eca-109 and HeLa cells, the inhibitory activity of complex 1 is stronger than that of 2. We further observed that complex 1 inhibited the growth of HeLa cells through inducing the apoptosis and arresting cell cycle at S phase. Our results suggested that both complexes 1 and 2 have DNA- and protein-binding capacity and antitumor activity.

Crystal structure of (Z)-N'-[1-(3-methyl-5-oxo-1-phenyl-1,5-di-hydro-4H-pyrazol-4-yl-idene)prop-yl]benzene-sulfono-hydrazide.

The title compound, C19H20N4O3S, was synthesized by refluxing equimolar amounts of 1-phenyl-3-methyl-4-propionylpyrazol-5-one and benzene-sulfonyl hydrazide in ethanol. The compound crystallizes in the keto form and the carbonyl O atom forms an intra-molecular N-H⋯O hydrogen bond with the neighbouring NH group. There is also C-H⋯O short contact involving the neighbouring phenyl ring. Probably as a result of this, the phenyl ring is inclined to the pyrazolone ring by only 7.58 (12)°. The dihedral angle between the phenyl ring and the benzene-sulfonyl ring is 22.78 (11)°. In the crystal, mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R (2) 2(14) ring motif. The dimers are linked via pairs of C-H⋯O hydrogen bonds, forming chains propagating along [100].

Phase transitions, prominent dielectric anomalies, and negative thermal expansion in three high thermally stable ammonium magnesium-formate frameworks.

We present three Mg-formate frameworks, incorporating three different ammoniums: [NH4][Mg(HCOO)3] (1), [CH3CH2NH3][Mg(HCOO)3] (2) and [NH3(CH2)4NH3][Mg2(HCOO)6] (3). They display structural phase transitions accompanied by prominent dielectric anomalies and anisotropic and negative thermal expansion. The temperature-dependent structures, covering the whole temperature region in which the phase transitions occur, reveal detailed structural changes, and structure-property relationships are established. Compound 1 is a chiral Mg-formate framework with the NH4(+) cations located in the channels. Above 255 K, the NH4(+) cation vibrates quickly between two positions of shallow energy minima. Below 255 K, the cations undergo two steps of freezing of their vibrations, caused by the different inner profiles of the channels, producing non-compensated antipolarization. These lead to significant negative thermal expansion and a relaxor-like dielectric response. In perovskite 2, the orthorhombic phase below 374 K possesses ordered CH3CH2NH3(+) cations in the cubic cavities of the Mg-formate framework. Above 374 K, the structure becomes trigonal, with trigonally disordered cations, and above 426 K, another phase transition occurs and the cation changes to a two-fold disordered state. The two transitions are accompanied by prominent dielectric anomalies and negative and positive thermal expansion, contributing to the large regulation of the framework coupled the order-disorder transition of CH3CH2NH3(+). For niccolite 3, the gradually enhanced flipping movement of the middle ethylene of [NH3(CH2)4NH3](2+) in the elongated framework cavity finally leads to the phase transition with a critical temperature of 412 K, and the trigonally disordered cations and relevant framework change, providing the basis for the very strong dielectric dispersion, high dielectric constant (comparable to inorganic oxides), and large negative thermal expansion. The spontaneous polarizations for the low-temperature polar phases are 1.15, 3.43 and 1.51 µC cm(-2) for 1, 2 and 3, respectively, as estimated by the shifts of the cations related to the anionic frameworks. Thermal and variable-temperature powder X-ray diffraction studies confirm the phase transitions, and the materials are all found to be thermally stable up to 470 K.

Tuning size and magnetic thermal hysteresis in a new near room temperature spin crossover compound.

A mononuclear spin crossover compound Fe(AP-Mesal)2, which exhibits spin transitions near room temperature and light induced excited spin state trapping (LIESST) effects at low temperature, was synthesized and substructured in the form of micro- and nanoscaled particles. A thermal hysteresis loop was detected with particle size reduction to microscale and nanoscale.

Syntheses, structure diversity and properties of complexes with 4-acyl pyrazolone salicylidene hydrazide derivatives.

Five new complexes [Zn(HL(1))(OAc)(CH(3)CH(2)OH)] (1), [Cd(2)(HL(1))(2)(OAc)(2)(CH(3)CH(2)OH)(2)] (2), [Cu(6)(L(1))(6)] (3) (H(2)L(1) = N-(1-phenyl-3-phenmethyl-4-phenylethylene-pyrazolone-5)-salicylidene hydrazide, OAc = acetate anion), {[Zn(L(2))(CH(3)OH)]·(CH(3)OH)}(n) (4) (H(2)L(2) = N-(1-phenyl-3-phenmethyl-4-ethylene-pyrazolone-5)-salicylidene hydrazine), [Cu(L(3))](n) (5) (H(2)L(3) = N-(1-phenyl-3-phenmethyl-4-benzylidene-pyrazolone-5)-salicylidene hydrazide) have been synthesized and characterized by chemical and spectroscopic techniques. Complexes 1-3 feature mononuclear, dinuclear and rare hexanuclear structures, respectively. The different molecular structures and different coordination modes of H(2)L(1) in complexes 1-3 indicate that the coordination geometry of the metal atoms have a remarkable impact on the structure of these complexes. Complexes 4 and 5 have 1D chain structures. Comparing complexes 4 and 1 or 5 and 3, it can be concluded that the substituents at the 4-position of the ligands have a significant effect on the structure of the resulting complexes. It is worth noting that N(2) atoms of the pyrazolyl ring play an important role in building the two-dimensional networks for 1 and 2 by hydrogen bonds, a novel hexanuclear unit for 3, and the 1D polymer chain for 4 and 5 by bridging bonds. Complexes 1, 2 and 4 show strong fluorescent behavior in the solid state. The magnetic property of complex 3 shows the presence of intramolecular antiferromagnetic exchange (J = -8.63 cm(-1)).

Coexistence of magnetic and electric orderings in the metal-formate frameworks of [NH4][M(HCOO)3].

A family of three-dimensional chiral metal-formate frameworks of [NH(4)][M(HCOO)(3)] (M = Mn, Fe, Co, Ni, and Zn) displays paraelectric to ferroelectric phase transitions between 191 and 254 K, triggered by disorder-order transitions of NH(4)(+) cations and their displacement within the framework channels, combined with spin-canted antiferromagnetic ordering within 8-30 K for the magnetic members, providing a new class of metal-organic frameworks showing the coexistence of magnetic and electric orderings.

Single-molecule-magnet behavior in a Fe(12)Sm(4) cluster.

Through the combination of Sm(III) spin carriers with a Fe(III) system, the largest Fe-Ln cluster so far has been synthesized. To our knowledge, the new complex, Fe(12)Sm(4), is the first Sm(III) single-molecule magnet. Furthermore, Fe(12)La(4) and Fe(12)Gd(4) have also been synthesized to help understand the magnetic exchange interactions and origin of magnetic anisotropy in Fe(12)Sm(4).

Disorder-order ferroelectric transition in the metal formate framework of [NH4][Zn(HCOO)3].

A three-dimensional chiral metal formate framework compound, [NH(4)][Zn(HCOO)(3)], undergoes a paraelectric-ferroelectric phase transition at 191 K triggered by the disorder-order transition of NH(4)(+) cations within the structure.

Abrupt spin transition around room temperature and light induced properties in Fe(II) complexes with N4O2 coordination sphere.

Mononuclear spin-crossover complex Fe(II)(L)(2) x CH(3)OH (1 x CH(3)OH) and its desolvated product 1 exhibit abrupt spin transitions around room temperature. 1 also shows a light induced excited spin state trapping (LIESST) effect and a light induced thermal hysteresis (LITH) phenomenon at low temperature.

One-dimensional ferromagnetically coupled bimetallic chains constructed with trans-[Ru(acac)2(CN)2]-: syntheses, structures, magnetic properties, and density functional theoretical study.

Four cyano-bridged 1D bimetallic polymers have been prepared by using the paramagnetic building block trans-[Ru(acac)(2)(CN)(2)](-) (Hacac=acetylacetone): {[{Ni(tren)}{Ru(acac)(2)(CN)(2)}][ClO(4)].CH(3)OH}(n) (1) (tren=tris(2-aminoethyl)amine), {[{Ni(cyclen)}{Ru(acac)(2)(CN)(2)}][ClO(4)].CH(3)OH}(n) (2) (cyclen=1,4,7,10-tetraazacyclododecane), {[{Fe(salen)}{Ru(acac)(2)(CN)(2)}]}(n) (3) (salen(2-)=N,N'-bis(salicylidene)-o-ethyldiamine dianion) and [{Mn(5,5'-Me(2)salen)}(2){Ru(acac)(2)(CN)(2)}][Ru(acac)(2)(CN)(2)].2CH(3)OH (4) (5,5'-Me(2)salen=N,N'-bis(5,5'-dimethylsalicylidene)-o-ethylenediimine). Compounds 1 and 2 are 1D, zigzagged NiRu chains that exhibit ferromagnetic coupling between Ni(II) and Ru(III) ions through cyano bridges with J=+1.92 cm(-1), zJ'=-1.37 cm(-1), g=2.20 for 1 and J=+0.85 cm(-1), zJ'=-0.16 cm(-1), g=2.24 for 2. Compound 3 has a 1D linear chain structure that exhibits intrachain ferromagnetic coupling (J=+0.62 cm(-1), zJ'=-0.09 cm(-1), g=2.08), but antiferromagnetic coupling occurs between FeRu chains, leading to metamagnetic behavior with T(N)=2.6 K. In compound 4, two Mn(III) ions are coordinated to trans-[Ru(acac)(2)(CN)(2)](-) to form trinuclear Mn(2)Ru units, which are linked together by pi-pi stacking and weak Mn...O* interactions to form a 1D chain. Compound 4 shows slow magnetic relaxation below 3.0 K with phi=0.25, characteristic of superparamagnetic behavior. The Mn(III)...Ru(III) coupling constant (through cyano bridges) and the Mn(III)...Mn(III) coupling constant (between the trimers) are +0.87 and +0.24 cm(-1), respectively. Compound 4 is a novel single-chain magnet built from Mn(2)Ru trimers through noncovalent interactions. Density functional theory (DFT) combined with the broken symmetry state method was used to calculate the molecular magnetic orbitals and the magnetic exchange interactions between Ru(III) and M (M=Ni(II), Fe(III), and Mn(III)) ions. To explain the somewhat unexpected ferromagnetic coupling between low-spin Ru(III) and high-spin Fe(III) and Mn(III) ions in compounds 3 and 4, respectively, it is proposed that apart from the relative symmetries, the relative energies of the magnetic orbitals may also be important in determining the overall magnetic coupling in these bimetallic assemblies.

Synthesis, magnetic and photomagnetic study of new iron(II) spin-crossover complexes with N4O2 coordination sphere.

A new family of neutral mononuclear iron(II) spin crossover (SCO) compounds, Fe(L¹â»6)2 (L¹â»6 = N'-((pyridin-2-yl)methylene)benzohydrazide (HL¹), N'-(1-(pyridin-2-yl)ethylidene)-benzohydrazide (HL²), N'-(phenyl(pyridin-2-yl)methylene)benzohydrazide (HL³), 2-hydroxy-N'-((pyridin-2-yl)methylene)benzohydrazide (HL4), 2-hydroxy-N'-(1-(pyridin-2-yl)ethylidene)benzohydrazide (HL5), 2-hydroxy-N'-(phenyl(pyridin-2-yl)methylene)benzohydrazide (HL6)) with N4O2 donor sets have been synthesized from series tridentate Schiff base ligands with N,N,O donor sets. The investigation of magnetic properties of these compounds reveal that in the measured temperature range, compound 1 is in the high-spin (HS) state, and compound 3 and 6 are mainly in the low-spin (LS) state, whereas the other compounds exhibit various SCO properties: compound 2 undergoes a gradual incomplete SCO with characteristic temperature T(1/2) higher than 350 K; compound 4 exhibits a special stepwise thermally induced SCO occurring at ~150 K (smooth) and 200 K (two-steps, with T(S1↑/↓) = 204/202 K and T(S2↑/↓) = 227/219 K) with a mixture of the HS and LS states yielded below 100 K; compound 5 shows a gradual and complete LS↔HS SCO with characteristic temperature T(1/2) = 273 K. All the three SCO compounds show the LIESST (light induced exited spin state trapping) effect with different levels of photoconversion. To thoroughly analyze these behaviours, Mössbauer spectra and DSC of 4 and 5, crystal structures of all the compounds at 290 K and 5 in the LS state at 110 K were carried out, which confirmed the structural changes accompanying the spin transition. In addition, alkyl substitution effect on the ligand field was suggested for this system.