Mixed Azide and 5-(Pyrimidyl)tetrazole Bridged Co(II)/Mn(II) Polymers: Synthesis, Crystal Structures, Ferroelectric and Magnetic Behavior

Fabrication of localized surface plasmon resonance sensors with scalable polyvinyltetrazole/copper cluster hybrid ring-array for Cu(II) detection

The bottom of a hole-array photoresist template deposited with a hydrophobic atom-transfer radical polymerization (ATRP) initiator was wetted by treatment with oxygen plasma. After the removal of the photoresist template, ring patterns of the ATRP initiator were formed at the interface between the hydrophobic and wetting regions. Polyacrylonitrile (PAN) was grafted from the initiator ring array to covert to polyvinyltetrazole (PVT) rings via a cyano-to-tetrazole reaction, which could adsorb Cu(II) at various concentrations. The Cu(II) ions within the PVT rings were reduced to form a PVT-copper hybrid ring (VCHR), resulting in a blue-shift of the localized surface plasmon resonance (LSPR) peak as the Cu(II) was adsorbed by the PVT rings. The blue-shift and Cu(II) concentration were linearly correlated, with a detection limit of ∼25 pg mL^-1 and a linear range of 25-400 pg mL^-1 for Cu(II) detection. Although the PVT rings also chelated Pb(II) and Cr(III), these ions did not exhibit obvious LSPR peaks. The VCHR LSPR sensor exhibited excellent selectivity for Cu(II) detection. Combining lithography and plasma technology provides a versatile platform for developing the scalable ring structure of copper for highly sensitive and selective Cu(II) sensing.

Inorganic-Organic Hybrid Molecular Materials: From Multiferroic to Magnetoelectric

Inorganic-organic hybrid molecular multiferroic and magnetoelectric materials, similar to multiferroic oxide compounds, have recently attracted increasing attention because they exhibit diverse architectures, a flexible framework, fascinating physics, and potential magnetoelectric functionalities in novel multifunctional devices such as energy transformation devices, sensors, and information storage systems. Herein, the classification of multiferroicity and magnetoelectricity is briefly outlined and then the recent advances in the multiferroicity and magnetoelectricity of inorganic-organic hybrid molecular materials, particularly magnetoelectricity and the relevant magnetoelectric mechanisms and their categories are summarized. In addition, a personal perspective and an outlook are provided.

Luminescent metal organic frameworks for sensing and gas adsorption studies

Two three-dimensional metal organic frameworks (LZn and LCd) were synthesized solvothermally for sensing of nitro phenolic explosives and gas adsorption studies. LZn showed selectivity towards N₂ gas at 77 K.

Structural diversity and magnetic properties of six cobalt coordination polymers based on 2,2'-phosphinico-dibenzoate ligand

Six novel Co(ii) coordination polymers, namely, [Co₁₀L₆(OH)₂(H₂O)₉]·10.5H₂O (1), [Co₃L₂(3-abpt)₂]·4H₂O (2), [Co₃L₂(4-azpy)₂(H₂O)₂(EtOH)] (3), [Co₃L₂(4,4'-bipy)₂(H₂O)₂(MeCN)] (4), [Co₃L₂(4,4'-bipy)₂] (5), and [Co₅L₂(OH)₂(ina)₂(H₂O)₂] (6) (H₃L = 2,2'-phosphinico-dibenzoic acid, 3-abpt = 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole, 4-azpy = 4,4'-azobispyridine, 4,4'-bipy = 4,4'-bipyridine, Hina = isonicotinic acid), have been hydrothermally synthesized and their magnetic properties have been characterized. The L^3- anion displays six types of coordination modes in the compounds. Compound 1 exhibits a novel 1D ladder-like structure, which consists of non-centrosymmetric Co₁₀ units. Compounds 2-4 comprise 2D networks assembled from Co₃L₂ chains and N-heterocyclic linkers. Compound 5 comprises a 3D framework built from six neighboring parallel Co₃L₂ ladders bridged by 4,4'-bipy linkers. Compound 6 features a 3D framework that exhibits pcu topology with the Schläfli symbol of (4¹²·6³) using a pentanuclear [Co₅(OH)₂]⁸⁺ cluster as the node. Variable-temperature magnetic susceptibility studies indicate that the six coordination polymers exhibit remarkable magnetic behavior such as spin-canted antiferromagnetism and spin glass, which were found to coexist in compound 6.

Construction of magnet-type coordination polymers using high-spin {Ni4}-citrate cubane as secondary building units

A robust ferromagnetic secondary building unit based on {Ni₄}-citrate cubane is identified to be able to construct diverse structures while retaining the original magnetism.

Azide-bridged Cu(ii), Mn(ii) and Co(ii) coordination polymers constructed with a bifunctional ligand of 6-(1H-tetrazol-5-yl)-2,2′-bipyridine

Three new azide-bridged coordination polymers, [M(N₃)(tzbp)]_n (M = Cu, 1·Cu; Mn, 2·Mn; Co, 3·Co), were successfully prepared by introducing a bifunctional tetrazolate/2,2′-bipyridine ligand, 6-(1H-tetrazol-5-yl)-2,2′-bipyridine (Htzbp).

Crystal structure of 4-methyl-sulfanyl-2-(2H-tetra-zol-2-yl)pyrimidine

The title compound, C6H6N6S, crystallized with two independent mol-ecules (A and B) in the asymmetric unit. The conformation of the two mol-ecules differs slightly. While the tetra-zole ring is inclined to the pyrim-idene ring by 5.48 (7) and 4.24 (7)° in mol-ecules A and B, respectively, the N-C-S-C torsion angles of the thio-methyl groups differ by ca 180°. In the crystal, the A and B mol-ecules are linked via a C-H⋯N hydrogen bond. They stack along the b-axis direction forming columns within which there are weak π-π inter-actions present [shortest inter-centroid distance = 3.6933 (13) Å].

Tetrazolate–azido–copper(ii) coordination polymers: tuned synthesis, structure, and magnetic properties

Two antiferrimagnetic tetrazolate–azido–copper(ii) coordination polymers, [Cu(tz)(N₃)]_n (1) and [Cu(tz)(N₃)(NH₃)₂]_n (2) with distinct topological structures were synthesized under different reaction conditions and structurally characterized.

A Ni(ii) dinuclear complex bridged by end-on azide-N and phenolate-O atoms: spectral interpretation, magnetism and biological study

A new dinuclear complex, [Ni(L)(μ_1,1-N₃)Ni(L)(OH₂)₂]·ClO₄(1), has been synthesized. It shows the presence of ferromagnetic interactions and is endowed with both anti-mycobacterial and anticancer properties.

((1H-tetrazol-5-yl) methyl) pyridine-based metal coordination complexes: in situ tetrazole synthesis, crystal structures, luminescence properties

Six novel transition metal coordination complexes based on pyridyltetrazole ligands have been hydrothermally in situ synthesized.

Synthesis, crystal structure and magnetic properties of two alternating double μ1,1 and μ1,3 azido bridged Cu(ii) and Ni(ii) chains

Two new alternating double μ_1,1 and μ_1,3 azido bridged 1D Cu(ii) and Ni(ii) complexes have been synthesized and their magnetic data were fitted to an alternating ferro/antiferromagnetic chain model.

Layered transition metal carboxylates: synthesis, structural aspects and observation of multi-step magnetic transition through phase diagram

Two new layered transition metal carboxylate frameworks, [Co3(L)2(H2O)6]·2H2O () and [Ni3(L)2(H2O)6]·2H2O () (L = tartronate anion or hydroxymalonic acid), have been synthesized and characterized by X-ray single crystal analysis. Both compounds have similar 2D structures. In both compounds there are two types of metal centers where one center is doubly bridged by the alkoxy oxygen atoms through μ2-O bridging to form a 1D infinite chain parallel to the crystallographic b-axis with the corners shared between the metal polyhedra. Magnetic susceptibility measurements revealed the existence of antiferromagnetic short range correlations between Co(Ni) intra-chain metal centers (with exchange constants JCo = -22.6 and JNi = -35.4 K). At low temperatures, long range order is observed in both compounds at Néel temperatures of 11 (for ) and 16 (for ) K, revealing that other exchange interactions, rather than the intra-chain ones, play a role in these systems. Whereas compound has an antiferromagnetic ground state, compound exhibits a ferromagnetic component, probably due to spin canting. Isothermal magnetization data unveiled a rich phase diagram with three metamagnetic phase transitions below 8 K in compound .

First one-dimensional homochiral stairway-like Cu(II) chains: crystal structures, circular dichroism (CD) spectra, ferroelectricity and antiferromagnetic properties

The reactions of enantiopure chiral ligands (+)/(−)-4,5-pinenepyridyl-2-pyrazine (LS/LR) with CuCl2·2H2O in CH3OH/CH2Cl2 solution led to the formations of one-dimensional homochiral enantiomeric pairs with the formula [Cu(LR/S)Cl2]n·2H2O (R-1 and S-1, the isomers containing the LR and LS ligands, respectively). The circular dichroism (CD) spectra verified their chiroptical activities and enantiomeric natures. Their structures have been determined by X-ray single-crystal analyses, showing stairway-like and mirror-symmetric features, which represent the first examples of homochiral metal complexes with stairway-like structures. The ferroelectric property measurement indicated that R-1 exhibits ferroelectricity with the remnant polarization (Pr) value of 0.02 μC cm−2 under an applied electric field of 6.1 kV cm−1 at room temperature. The magnetic investigation of R-1 showed a weak intrachain antiferromagnetic coupling between Cu(II)–Cu(II) ions mediated by pyrazine, which can be interpreted by a spin-polarization mechanism. All these results suggested that R-1 and S-1 are potential multifunctional molecule-based materials combining optical activity, ferroelectricity and magnetism within one molecule.