Six-Coordinated Co Single-Molecule Magnets: Synthetic Strategy, Structure and Magnetic Properties.

The pursuit of molecule-based magnetic memory materials contributes significantly to high-density information storage research in the frame of the ongoing information technologies revolution. Remarkable progress has been achieved in both transition metal (TM) and lanthanide based single-molecule magnets (SMMs). Notably, six-coordinated Co SMMs hold particular research significance owing to the economic and abundant nature of 3d TM ions compared to lanthanide ions, the substantial spin-orbit coupling of Co ions, the potential for precise control over coordination geometry, and the air-stability of coordination-saturated structures.

The role of intermolecular interactions in [Fe(X-salEen)]ClO spin crossover complexes.

Two new spin crossover (SCO) Fe(III) compounds were prepared, their structures were analysed and their magnetic properties were investigated. An exhaustive analysis of the effects of halogen substitution and aromatic ring functionalisation on the magnetic properties of non-solvated Fe(III) perchlorate complexes has been performed. Through comparative analysis, different magnetic profiles were found for the compounds studied, namely F (1), Cl (2), H (3), Br (4a, 4b), and I (5).

Synthesis, Crystal Structures, Genotoxicity, and Antifungal and Antibacterial Studies of Ni(II) and Cd(II) Pyrazole Amide Coordination Complexes.

In this study, we synthesized two coordination complexes based on pyrazole-based ligands, namely 1,5-dimethyl--phenyl-1H-pyrazole-3-carboxamide () and 1,5-dimethyl--propyl-1H-pyrazole-3-carboxamide (), with the aim to investigate bio-inorganic properties. Their crystal structures revealed a mononuclear complex [Ni()](ClO) () and a dinuclear complex [Cd()]Cl (). Very competitive antifungal and anti-Fusarium activities were found compared to the reference standard cycloheximide.

Incorporation of Photo- and Thermoresponsive -Salicylidene Aniline Derivatives into Cobalt and Zinc Layered Hydroxides.

In search of new multifunctional hybrid materials and in order to investigate the influence of chemical modification on the possible synergy between properties, the carboxylate and sulfonate derivatives of photo- and thermochromic N-salicylidene aniline were successfully inserted into Co(II)- and Zn(II)-based layered simple hydroxides, resulting in four novel hybrids: Co--Sali-COO, Co--Sali-SO, Zn--Sali-COO, and Zn--Sali-SO. All synthesized hybrids adopt a double organic layered configuration, which prevents the photoisomerization ability of -Sali-R molecules in the hybrids. However, the Zn hybrids exhibit fluorescence upon exposure to UV light due to the excited-state intramolecular proton transfer (ESIPT) mechanism.

New triazole-based coordination complexes as antitumor agents against triple negative breast cancer MDA-MB-468 cell line.

The present work describes the synthesis of a new triazole based ligand 3-(3,5-dimethyl-1-pyrazol-1-yl)-1-methyl-1-1,2,4-triazole (LM) and demonstration of its coordination diversity giving rise to a family of seven new coordination complexes, namely: [Ni(LM)](ClO)·CHOS (5), [Co(LM)](ClO)·(CH)O (6), [Cd(LM)Cl] (7), [Cu(LM)NO]NO (8), [Fe(LM)](BF) (9), [Zn(LM)](BF) (10) and [Zn(LM)NO]NO (11), whose crystal structure was determined by single-crystal X-ray diffraction. Cytotoxic activity was evaluated against the MDA-MB-468 cancer cell line, which serves as a model for triple-negative breast cancer, and compared to the precursor molecule (L), as well as their coordination complexes (HO){[NiL](ClO)} (1), [CoL](ClO)·2HO (2), [CdLCl] (3) and [CuL](NO) (4), for which the crystal structure was earlier determined. Notably, cadmium complexes 3 and 7 exhibit remarkable cytotoxicity and demonstrated a high selectivity index towards cancer cells when compared to peripheral blood mononuclear cells.

Spin-state versatility in FeII4L supramolecular cages with a pyridyl-hydrazone ligand scaffold modulated by solvents and counter anions.

Discrete spin crossover (SCO) tetranuclear cages are a unique class of materials that have potential use in next-generation molecular recognition and sensing. In this work, two new edge-bridged SCO FeII4L (L = 2,7-bis((()-pyridin-2-ylmethylene)amino)benzo[] [3,8]phenanthroline-1,3,6,8(2,7)-tetraone) supramolecular cages with different counter anions: ClO (2) and CFSO (3) were constructed subcomponent self-assembly to investigate both solvent and anion influences on their magnetic properties and compare them to cage 1 with a BF anion. Pyridyl-hydrazone bidentate ligand scaffolds were employed to replace the 'classical' imidazole/thiazolyl-imine coordination units to induce SCO behaviour in these cages.

Coordination Complexes Built from a Ditopic Triazole-Pyrazole Ligand with Antibacterial and Antifungal Performances.

Four mononuclear complexes (HO){[NiL](ClO)} (), [CoL](ClO)·2HO (), [CdLCl] () and [CuL](NO) () have been prepared employing a newly synthesized 1,2,4-triazole ligand: 3-(3,5-dimethyl-1-pyrazol-1-yl)-1-1,2,4-triazole (). The structures of the complexes, which crystallized in (), (), (), and (), are reviewed within the context of the cooperative effect of the hydrogen bonding network and counter anions on the supramolecular formations. Moreover, within the framework of biological activity examination, these compounds showed favorable antibacterial performances compared to those of various species of bacteria, including both Gram-positive and Gram-negative strains.

Interpenetration Phenomena via Anion Template Effects in Fe(II) and Co(II) Coordination Networks with a Bis-(1,2,4-triazole) Ligand.

Seven new coordination networks, [Fe(tbbt)](BF) (), [Co(tbbt)](BF) (), [Fe(tbbt)](ClO) (), [Co(tbbt)](ClO) (), [Fe(NCS)(tbbt)] (), [Co(NCS)(tbbt)] (), and [Fe(HO)(tbbt)]Br·2HO (), were synthesized with the linker 1,1'-(-2-butene-1,4-diyl)bis-1,2,4-triazole (tbbt) and structurally investigated. The structure of complexes - is composed of three interpenetrating, symmetry-related 3D networks. Each individual 3D network forms a primitive, nearly cubic lattice () with BF or ClO anions present in the interstitial spaces.

A spin crossover FeL cage based on pyridyl-hydrazone sites.

Reported here is the first Fe based supramolecular cage with pyridyl-hydrazone ligand scaffolds that exhibits temperature induced spin crossover behaviour. Density functional theory calculations were employed to investigate the cause of the occurrence of this phenomenon based on the ligand structure. These results indicate that the reported low-spin cages with pyridyl-imine sites could be reconsidered for spin crossover by carefully manipulating the functional groups in the ligand system.

Novel family of bis-pyrazole coordination complexes as potent antibacterial and antifungal agents.

A new pyrazole ligand, ,-bis(2(1',5,5'-trimethyl-1,1'-[3,3'-bipyrazol]-1-yl)ethyl)propan-1-amine (L) was synthesized and characterized by H-NMR, C-NMR, FT-IR and HRMS. The coordination ability of the ligand has been employed for the construction of a new family of coordination complexes, namely: [CuLCl] (1), [ML(CHOH)(HO)](ClO) (M = Ni (2), Co (3)) and [FeL(NCS)] (4). The series of complexes were characterized using single-crystal X-ray diffraction, HRMS, FT-IR and UV-visible spectroscopy.

A non-porous Fe(II) complex for the colorimetric detection of hazardous gases and the monitoring of meat freshness.

Food quality monitoring and freshness assessment are critical for ensuring food safety at a large scale. Ammonia is used as an important indicator of protein rich food spoilage state. However, current ammonia gas sensors suffer from insufficient sensitivity and selectivity, or sophisticated instrumentation, hindering their practical application in in-situ and real-time food quality monitoring.

Synthesis and cytotoxicity against tumor cells of pincer N-heterocyclic ligands and their transition metal complexes.

The complexes: [CoL](ClO) (1), [FeL](ClO) (2), [NiL](ClO) (3) and [MnLCl] (4), with L = diethyl-1,1'-(pyridine-2,6-diyl)bis(5-methyl-1-pyrazole-3-carboxylate), were synthesized and fully characterized. Structural analysis revealed two distinct patterns influenced by the counter ions where L acts as a tridentate chelating ligand. The antitumor activity of L and L' (diethyl 2,2'-(pyridine-2,6-diylbis(5-methyl-1-pyrazole-3,1-diyl)) diacetate) as well as their metal complexes, was tested by the measurement of their cytostatic and cytotoxic properties towards the blood cancer mastocytoma cell line P815.

Coordination complexes constructed from pyrazole-acetamide and pyrazole-quinoxaline: effect of hydrogen bonding on the self-assembly process and antibacterial activity.

Two mononuclear coordination complexes of -(2-aminophenyl)-2-(5-methyl-1-pyrazol-3-yl)acetamide (L), namely [Cd(L)Cl] (C) and [Cu(L)(CHOH)](NO) (C) and one mononuclear complex [Fe(L)(HO)](NO)·2HO (C), obtained after oxidation of L, have been synthesized and characterized spectroscopically. As revealed by single-crystal X-ray diffraction, each coordination sphere made of two heterocycles is completed either by two chloride anions (in C), two ethanol molecules (in C) or two water molecules (in C). The crystal packing analysis of C, C and C, revealed 1D and 2D supramolecular architectures, respectively, various hydrogen bonding interactions, which are discussed in detail.

Kinetics, thermodynamics, equilibrium, surface modelling, and atomic absorption analysis of selective Cu(ii) removal from aqueous solutions and rivers water using silica-2-(pyridin-2-ylmethoxy)ethan-1-ol hybrid material.

The removal of heavy metals is attracting considerable attention due to their undesirable effects on the environment. In this investigation, a new adsorbent based on silica functionalized with pyridin-2-ylmethanol (SiPy) was successfully synthesized to yield to a hybrid material. FTIR, SEM, TGA, and specific surface area analysis were used to characterize the structure and morphology of the SiPy hybrid material.

Thin Films of Nanocrystalline Fe(pz)[Pt(CN)] Deposited by Resonant Matrix-Assisted Pulsed Laser Evaporation.

Prior studies of the thin film deposition of the metal-organic compound of Fe(pz)Pt[CN] (pz = pyrazine) using the matrix-assisted pulsed laser evaporation (MAPLE) method, provided evidence for laser-induced decomposition of the molecular structure resulting in a significant downshift of the spin transition temperature. In this work we report new results obtained with a tunable pulsed laser, adjusted to water resonance absorption band with a maximum at 3080 nm, instead of 1064 nm laser, to overcome limitations related to laser-target interactions. Using this approach, we obtain uniform and functional thin films of Fe(pz)Pt[CN] nanoparticles with an average thickness of 135 nm on Si and/or glass substrates.

A Highly Efficient Environmental-Friendly Adsorbent Based on Schiff Base for Removal of Cu(II) from Aqueous Solutions: A Combined Experimental and Theoretical Study.

Removal of heavy metals from drinking water sources and rivers is of strategic health importance and is essential for sustainable ecosystem development, in particular in polluted areas around the globe. In this work, new hybrid inorganic-organic material adsorbents made of ortho- () or para-Schiff base silica () were synthesized and characterized in depth. These hybrid adsorbents show a high selectivity to Cu(II), even in the presence of competing heavy metals (Zn(II), Cd(II), and Pb(II)), and also demonstrate great reusability after five adsorption-desorption cycles.

Auxiliary alkyl chain modulated spin crossover behaviour of [Fe(HBpz)(C-bipy)] complexes.

Three new alkyl chain substituted complexes [Fe(HBpz)(C-bipy)] (pz = pyrazolyl, C-bipy = bipyridine alkyl chain diester, = 3 (3), 4 (4) and 5 (5)) show versatile spin state switching behaviour with different "tail" lengths as revealed by structural and magnetic analyses. The most striking phenomenon is observed for 5 which undergoes an abrupt spin transition accompanied by thermal hysteresis of 10 K, which is attributed to crystal packing effects derived from the competition between π⋯π and C-H⋯O interactions. Interestingly, each of the complexes exhibits similar gradual and complete spin crossover in methanol solution with a transition temperature around 249 K, as deduced from temperature-dependent UV-vis spectroscopy.

Synthesis, Biochemical Characterization, and Theoretical Studies of Novel β-Keto-enol Pyridine and Furan Derivatives as Potent Antifungal Agents.

In the present study, we report the design and synthesis of new derivatives of the β-keto-enol grafted on pyridine and furan moieties ( - ). Structures of compounds were fully confirmed by Fourier transform infrared spectroscopy (FT-IR), H NMR, C NMR, electrospray ionization/liquid chromatography-mass spectrometry (ESI/LC-MS), and elemental analysis. The compounds were screened for antifungal and antibacterial activities (, , and ).

Efficient and Environmentally Friendly Adsorbent Based on β-Ketoenol-Pyrazole-Thiophene for Heavy-Metal Ion Removal from Aquatic Medium: A Combined Experimental and Theoretical Study.

A new sustainable and environmentally friendly adsorbent based on a β-ketoenol-pyrazole-thiophene receptor grafted onto a silica surface was developed and applied to the removal of heavy-metal ions (Pb(II), Cu(II), Zn(II), and Cd(II)) from aquatic medium. The new material was well characterized and confirms the success of covalent binding of the receptor on the silica surface. The effect of environmental parameters on adsorption including pH, contact time, temperature, and the initial concentration were investigated.

Solvent induced supramolecular polymorphism in Cu(II) coordination complex built from 1,2,4-triazolo[1,5-a]pyrimidine: Crystal structures and anti-oxidant activity.

Two Cu(II) coordination complexes, C1 and C2 of the formula [Cu(4)(HO)], have been prepared by reaction between CuCl·2HO and 7-ethoxycarbonylmethyl-5-methyl-1,2,4[1,5-a]pyrimidine (L) in a 1:2 M:L molar ratio. The L molecule decomposes during the reaction process into 7-carboxy-5-methyl-[1,2,4]-triazolo[1,5-a]pyrimidine (4) through an intermediate, ethyl 2,2-dihydroxy-2-(5-methyl-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl)acetate (5), which has been isolated and its crystal structure determined by X-ray diffraction. The X-ray analysis of the single crystals of [Cu(4)(HO)] obtained from the slow evaporation of EtOH and MeOH, separately, revealed the formation of "solvent induced" polymorphs C1 and C2, respectively.

Balancing Ligand Flexibility versus Rigidity for the Stepwise Self-Assembly of M L via M L Metal-Organic Cages.

Non-covalent interactions are important for directing protein folding across multiple intermediates and can even provide access to multiple stable structures with different properties and functions. Herein, we describe an approach for mimicking this behavior in the self-assembly of metal-organic cages. Two ligands, the bend angles of which are controlled by non-covalent interactions and one ligand lacking the above-mentioned interactions, were synthesized and used for self-assembly with Pd .

Highly Selective Removal of Pb(II) by a Pyridylpyrazole-β-ketoenol Receptor Covalently Bonded onto the Silica Surface.

Efficient materials capable of capturing toxic metals from water are widely needed. Herein, a new pyridylpyrazole-β-ketoenol receptor, X-ray diffraction analyzed, was covalently incorporated into the silica surface to produce solid and recyclable adsorbent particles. The new material, fully characterized, revealed extremely efficient removal of toxic metals from water, with a selectivity order of Pb(II) > Zn(II) > Cu(II) > Cd(II).

Highly Efficient Wideband Microwave Absorbers Based on Zero-Valent Fe@-FeO and Fe/Co/Ni Carbon-Protected Alloy Nanoparticles Supported on Reduced Graphene Oxide.

Electronic systems and telecommunication devices based on low-power microwaves, ranging from 2 to 40 GHz, have massively developed in the last decades. Their extensive use has contributed to the emergence of diverse electromagnetic interference (EMI) phenomena. Consequently, EMI shielding has become a ubiquitous necessity and, in certain countries, a legal requirement.