The present study focuses on the synthesis and structural characterization of a novel dinuclear CuII complex, [trichloridocopper(II)]-μ-chlorido-{bis[2-hydroxy-N′-(propan-2-ylidene)benzohydrazide]copper(II)} monohydrate, [Cu2Cl4(C10H12N2O2)2]·H2O or [Cu(H2L)2(μ-Cl)CuCl3]·H2O [H2L = 2-hydroxy-N′-(propan-2-ylidene)benzohydrazide]. The complex crystallizes in the monoclinic space group P21/n with one molecule of water, which forms interactions with the ligands. The first copper ion is penta-coordinated to two benzohydrazine-derived ligands via two nitrogen and two oxygen atoms, and one bridging chloride, which is also coordinated by the second copper ion alongside three terminal chlorines in a distorted tetrahedral geometry. The arrangement around the first copper ion exhibits a distorted geometry intermediate between trigonal bipyramidal and square pyramidal. In the crystal, chains are formed via intermolecular interactions along the a-axis direction, with subsequent layers constructed through hydrogen-bonding interactions parallel to the ac plane, and through slipped π–π stacking interactions parallel to the ab plane, resulting in a three-dimensional network. The intermolecular interactions in the crystal structure were quantified and analysed using Hirshfeld surface analysis. Residual electron density from disordered methanol molecules in the void space could not be reasonably modelled, thus a solvent mask was applied.

We report the synthesis, structure, and magnetic investigation of a novel one-dimensional copper (II) coordination polymer: formula [Cu( mu 1,1 -N 3 )( mu 1,3 -OAc)( mu-DMSO)] infinity (1) (OAc = acetate). The connection between neighbouring copper ions arises through a triple bridge involving EO type azide, syn-syn carboxylate and mu-DMSO molecule in apical positions forming an elongated octahedral coordination of copper ions. Magnetic susceptibility measurements show that complex (1) exhibits ferromagnetic intrachain interactions J chain = + 66 cm -1 whereas a metamagnetic behaviour occurs below 2.1 K related with antiferromagnetic inter-chain interactions with a critical field of 600 Oe at 1.8 K. DFT calculations were caried out to rationale the in-chain ferromagnetic interactions between copper ions. We found that the ferromagnetic coupling between copper ions is less sensitive to variation of bond length and/or Cu-N-Cu angle that may be caused by external stimulus such as temperature or pressure. (c) 2022 Elsevier B.V. All rights reserved.

The title compound, [Co(C10H9O3)(C12H8N2)2(H2O)]NO3 (I), crystallizes in the triclinic space group P with a monomeric [Co(3-meo-cin)(phen)2(H2O)]+ cation and a nitrate anion (3-meo-cin = 3-meth-oxy cinnamic acid) in the asymmetric unit. The CoII ion is coordinated by four N atoms from two 1,10-phenanthroline ligands and two O atoms, the first from a meth-oxy cinnamate ligand and the second from a coordinated water mol-ecule, forming a distorted octa-hedral geometry. Discrete entities of the cation and nitrate anion are formed by water-nitrate O-H⋯O and phen-nitrate C-H⋯O hydrogen bonds. The components are further assembled into chains along the c-axis direction. Layers are than formed by slipped π-π stacking inter-actions parallel to the bc plane. The inter-molecular inter-actions in the crystal structure were qu-anti-fied and analysed using Hirshfeld surface analysis.

The title compound, [Co(C10H9O3)(C12H8N2)2(H2O)]NO3 (I), crystallizes in the triclinic space group PUnlabelled Image with a monomeric [Co(3-meo-cin)(phen)2(H2O)]+ cation and a nitrate anion (3-meo-cin = 3-meth­oxy cinnamic acid) in the asymmetric unit. The CoII ion is coordinated by four N atoms from two 1,10-phenanthroline ligands and two O atoms, the first from a meth­oxy cinnamate ligand and the second from a coordinated water mol­ecule, forming a distorted octa­hedral geometry. Discrete entities of the cation and nitrate anion are formed by water–nitrate O—H⋯O and phen–nitrate C—H⋯O hydrogen bonds. The components are further assembled into chains along the c-axis direction. Layers are than formed by slipped π–π stacking inter­actions parallel to the bc plane. The inter­molecular inter­actions in the crystal structure were qu­anti­fied and analysed using Hirshfeld surface analysis.

The title compound, C 8 H 8 NO 4 + ·NO 3 − ·H 2 O, crystallizes in the same space group ( P 2 1 / c ) as the previously reported dihydrate form [Liang & Zhu (2010). Acta Cryst. E 66 , o667], but with two formula units per asymmetric unit instead of one. In the crystal, the components are linked into a three-dimensional network by classical intermolecular O—H...O and N—H...O hydrogen bonds and π–π stacking interactions. A Hirshfeld surface (HS) analysis indicated that the most important contributions to the crystal packing are from H...O/O...H (52.4%), H...H (13.9%) and C...C (11.2%) for one cation and H...O/O...H (46.3%), H...H (20%) and O...C/C...O (10.6%) for the other.

A series of lanthanide dinuclear complexes and chains incorporating two derivatives of cinnamic acid (2-methoxycinnamic acid and 3-methoxycinnamic acid) have been synthesized and characterized by elemental analyses, Infra-Red Spectroscopy, X-ray diffraction, photoluminescence and magnetic measurements. The use of the 2-methoxycinnamic ligand enables the synthesis of two dinuclear complexes (Eu3+ (1), Tb3+ (2)), while the presence of 3-methoxycinnamic acid induces the formation of one-dimensional coordination polymers (Eu3+ (3), Gd3+ (4)). Investigations of the magnetic properties reveals a field-induced slow relaxation of the magnetization for the gadolinium analogue 4, whereas the characteristic Eu3+ luminescence is observed for the europium-based materials 1 and 3.

Nine novel coordination compounds consisting of chains of lanthanide ions have been synthesized with the use of the ligand 3-ethoxycinnamate (L) to study the influence of the structural features on their magnetic properties. The new compounds belong to four different structural families, which are afforded with variations on the experimental conditions and selection of the lanthanide ion, their corresponding formulas being {[Ln(L)(3)(H2O)].DMF}(n) (Ln = Ce (1), Nd (2), Gd (3)), {[Ln(L)(3)][Ln(L)(3)(H2O)].DMF}(n) (Ln = Gd (4), Tb (5), Dy (6), Er (7)), and {[Ln(L)(3)][Ln(L)(3)(H2O)].DMSO}(n) (Ln = Dy (8), Yb ( 9)). Despite the fact that all of the compounds are based on the formation of infinite lanthanide-carboxylate chains, a structural study shows differences in the coordination environment of the lanthanide and in the bridging modes of the carboxylate groups. This is also reflected in the supramolecular packing of the chains formed. Investigations of their magnetic properties reveal a field-induced slow relaxation for compounds 2, 4, and 9.

The present study deals with the synthesis and characterization by single-crystal X-ray analysis and IR spectroscopy of two new Copper (II) complexes with bidentate Schiff base ligand [Nʹ-(propan-2-ylidene) thiophene-2-carbohydrazide] (HL). Depending on the copper salt used in the synthesis, a mononuclear or doubly chloro bridged dinuclear Copper (II) complexes of respective formula [Cu(L)2] (1) and [Cu2(μ-Cl)2(HL)2Cl2] (2) have been obtained. Magnetic study of complex 2 indicates the presence of weak antiferromagnetic interactions between the metal centers. To determine the antioxidant properties of both complexes, the ABTS radical scavenging and the reduction of copper (II)-neocuproine [Cu(II)–Nc] (CUPRAC) methods were used; 1 was more efficient than 2, for the two antioxidants assays. Lastly, Anti AChE activity method has been used to estimate in vitro anti-Alzheimer effect of 1 and 2 both of which show a potent AChE inhibition.

Two novel tridentate Schiff-base ligands containing carboxylate groups were obtained from the condensation of 3-amino-4-hydroxybenzoic acid with either acetylacetone (H3L1) or salicylaldehyde (H3L2). H3L1 reacted with copper(II) acetate and pyridine (strongly coordinating solvent) to afford the C1 complex, while reaction of H3L2 with nickel(II) acetate and pyridine afforded two types of complexes C2 and C3. The two ligands and their metal complexes were fully characterized by elemental analysis, XRD and spectroscopic analysis. Upon its fully deprotonated state, (L1)3− coordinates in a keto-enamine fashion and acts as a ditopic binder through an ONO tridentate donor system and an O monodentate donor system (carboxylate). Upon its doubly deprotonated state, (HL2)2− ligand acts either as monotopic tridentate binder (i.e. enol-imine form with an ONO donor system that lead to complex C2) or as a ditopic ligand (ONO tridentate and O monodentate donor systems to afford complex C3). The molecular structure of all the compounds were determined by single crystal X-ray diffraction studies and revealed several important characteristics. In complex C1, the Cu(II) cations are five-coordinated with a slightly distorted square pyramidal geometry, while in C2 and C3 complexes, the Ni(II) ions are four and six–coordinated with a square planar and a slightly distorted octahedral geometry, respectively. Following this structural investigation, the antioxidant activities of the free ligands and their metal complexes were then investigated and demonstrated interesting antioxidant features especially for H3L2 and complex C3. Lastly, temperature dependent magnetic susceptibility measurements showed the presence of ferromagnetic interactions in C1 mediated through the phenoxido bridges.

We report the synthesis, structure and magnetic properties of a series of heteroleptic Zn2+/Ln3+ complexes of the formula [ZnLClLn(o-van)(H2O)(NO3)]·H2O exhibiting slow relaxation of their magnetization.

Reaction of nickel chloride with acetylacetone bis(salicylhydrazone) (L) (prepared in situ by condensation of acetylacetone with salicylhydrazide) in methanol results in the formation of air-sensitive nickel (II) complex of symmetrical tetradentate Schiff base [NiII(L)] (1). Air oxidation of 1 leads to the formation of dinuclear species [NiII(L-L)NiII] (2) where the ligand (L-L)4– is formed by oxidative C-C coupling at the central methylene group of the acetylacetone fragment of (L)2–. The same reaction in methanol/pyridine solution leads to oxidative C-N coupling forming a mesoionic [NiII(L-Py)](3). The use of Nickel acetylacetonate in methanol/pyridine or DMSO solution under aerobic conditions provide [NiII(L-O)(py)2](4), [NiII(L-O)(DMSO)2](5). In this case, the ligand (L)2– is partially oxidized to form (L-O) which is formed by oxidation of the central methylene group. The molecular structure of 1–5 have been determined by X-ray crystallography. The first three complexes 1, 2 and 3 have a square-planar geometry, while, 4 and 5 adopt octahedral geometry. In vitro antioxidant activities of compounds 1, 4 and 5 were evaluated against DPPH radical and hydrogen peroxide and were compared with standard antioxidant, ascorbic acid. Our results reveal that the three compounds exhibit excellent radical scavenging activities. DFT calculations have been performed on complexes 1–5 using the BP86 and B3LYP functionals to provide a complete rationalization of their structures and to describe their electronic structures elucidating the fundamental spin state and the Metal-Ligand interaction type.

A series of dinuclear lanthanide complexes incorporating the 2-ethoxycinnamate ligand have been synthesized and characterized using elemental analyses, infra-red spectroscopy, X-ray diffraction and magnetic measurements. Depending on the nature of the lanthanide ion, three different isostructural series of respective formulas, [Ln(L)3(DMSO)(H2O)]2 (Ln = Ce (1), Nd (2)), [Ln(L)3(DMSO)x(DMF)y(H2O)]2 (Ln = Gd (3), Dy (5) and Er (6)) and [Tb(L)3(DMF)(H2O)]2 (4) have been obtained. Investigations of their magnetic properties reveal a genuine single-molecule magnet behaviour observed for the dysprosium based compound 5, while a field-induced slow relaxation of the magnetization is found for compounds 1, 2 and 3.

We report the synthesis, structure, and magnetic properties of a new dinuclear dysprosium(III) complex based on a 3-methoxycinnamate ligand. The centrosymmetric complex exhibits a field-induced SMM behavior. In contrast to the previously reported lanthanide-based systems with cinnamate derivatives that relax through a combination of Raman and direct processes, an Orbach process is also involved in highlighting the role of the structural organization over the spin-lattice relaxations.

We report here the synthesis and investigation into the magnetic properties of a luminescent trinuclear Zn2Dy Schiff-base complex that exhibits a zero-field single-molecule magnet behaviour. Magneto-structural correlation confirms that the axial crystal-field is generated by the phenoxide moieties while the characteristic Dy3+-based luminescence is observed.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.