Coexistence of Spin Canting and Metamagnetism in a One-Dimensional Mn(II) Compound Bridged by Alternating Double End-to-End and Double End-On Azido Ligands and the Analog Co(II) Compound

Biosynthesis of JC-La2CoO4 magnetic nanoparticles explored in catalytic and SMMs properties

We have reported the synthesis of JC-La2CoO4 magnetic nanoparticles from Jatropha Curcas L. leaf extract in aqueous medium and potential application study in catalytic & Single Molecule Magnets (SMMs). Several techniques were used to investigate the structural, morphological, and elemental composition, particle size, optical properties, catalytic and magnetic properties by XRD, FTIR, SEM, EDAX, XPS, UV-visible and squid magnetic measurement. It was found that the crystallite sizes and grain sizes of JC-La2CoO4 NPs were 11.3 ± 1 and 24.1 ± 1 nm respectively and surface morphology of the nanoparticles looks spherical shape with good surface area. The band gap of JC-La2CoO4 was found to be 4.95 eV indicates good semiconductor in nature. XPS studies shows that La and Co present in + 3 and + 2 oxidation state respectively and suggest the composition formula is La2CoO4 with satisfied all the valency of metal ions. The photocatalytic efficiency of La2CoO4 shows good result against methylene blue (MB) compared to other dyes like MO, NO, RhB in presence of sunlight with rate constant 56.73 × 10-3 min-1 and completely degraded within 115 mints. The importance of JC-La2CoO4 has magnetic properties with antiferromagnetic coupling and SMMs properties with nature.

Concomitant dimorphism in poly[di-μ-azido-(5,5′-dimethyl-2,2′-bipyridine)iron(II)]

The title metal–organic polymer, catena-poly[[(5,5′-dimethyl-2,2′-bipyridine-κ2 N,N′)iron(II)]-di-μ-azido-κ2 N 1:N 3-[(5,5′-dimethyl-2,2′-bipyridine-κ2 N,N′)iron(II)]-di-μ-azido-κ2 N 1:N 1], [Fe(N3)2(C12H12N2)] n , features alternating μ-1,1 (end-on mode of coordination) and μ-1,3 (end-to-end mode of coordination) double azide bridges, forming chains running in the [100] direction. The octahedral coordination geometry around the FeII centre is completed by a bidentate 5,5′-dimethyl-2,2′-bipyridine ligand. Two polymorphs for this compound were obtained from the crude reaction product, the first in the space group P\overline{1} and the other in P21/c. The molecular and crystal structures are very similar for both forms, the main difference being that the eight-membered Fe(μ-1,3-N3)2Fe metallacycle formed with end-to-end azide ligands has a nearly flat conformation in the triclinic form and a chair conformation in the monoclinic form. In spite of this geometric difference, both forms have the same density, the same packing index and similar arrangements of the one-dimensional chains in the crystal. As a consequence, they also share very similar Hirshfeld surfaces and fingerprint plots. However, a density functional theory (DFT) computational study showed that the monoclinic form is more stable than the triclinic form by ca 30.5 kJ mol−1.

A rare example of a double metamagnetic transition leading to 2D and 3D long-range order in the two-dimensional pyrazine- and azido-bridged cobalt(II) compound [Co(pyz)(N3)2]

The synthesis, characterization, crystal structure and detailed magnetic properties of a pyrazine (pyz) and azido (N₃) bridged cobalt(II) compound of formula [Co(N₃)₂(pyz)] (1) are reported. Compound 1 shows a layered structure formed by Co(II) chains with double μ-N₃(κN¹,N¹) bridges that are further connected by μ-(pyrazine-κN¹,N⁴) bridges. The layers present weak van der Waals interactions between azido terminal groups. The magnetic properties show the presence of a metamagnetic behaviour in 1 with two critical fields of 200 and 400 mT at low temperatures. AC magnetic measurements show the presence of a long-range 2D ferromagnetic order at T_c ≈ 8.0-7.0 K for dc fields above 200 mT and a long-range 3D ferromagnetic order at T_c ≈ 4.5 K for dc fields above 400 mT.

An Uneven Chain-like Ferromagnetic Copper(II) Coordination Polymer Displaying Metamagnetic Behavior and Long-Range Magnetic Ordering

Ferromagnetic coupling exists in an uneven chain-like copper(II) complex with both end-on azido and syn-syn carboxylato bridges, (Cu3(L)2(N3)4(H2O)3)n (1, HL = 6-hydroxynicotinic acid). It is the first example of one-dimensional (1D) chain-like copper(II) coordination polymer showing both metamagnetic behavior and long-range magnetic ordering (Tc = 6.7 K), thanks to the interchain hydrogen bonds, which make a three-dimensional (3D) supramolecular array of the entire molecular structure and mediate the interchain antiferromagnetic interaction.

Perspectives on Molecular Materials—A Tribute to Professor Peter Day

Professor Peter Day FRS was born on 20 August 1938 in Kent (UK) and attended Maidstone Grammar School [...]