A synthesis of six novel copper(II) compounds with a dinuclear molecule [Cu2(Ln)2], n 1/4 1-6 is presented with their structures determined. The initial ligand molecules H2Ln are of bis(phenol)amine type having the third amine arm composed by-CH2THF (1-4) or-CH2CH2OMe (5, 6) moieties, respectively. Their phenyl rings differ by the attached groups (t-Bu/MeO 1, t-Bu/Me 2, Me/Me 3, Cl/Cl 4, t-Bu/Me 5, Me/Me 6) at orto/para positions. The XRD structural analysis demonstrates the surroundings of Cu(II) centers by three phenolates' oxygen atoms, one tetrahydrofuranyl/methoxyethyl oxygen atom (axial), and one amine nitrogen atom, showing distorted square-pyramidal CuO3NO chromophores. One of the phenolates' oxygen atoms of each Ln connects the adjacent Cu(II) centers within the dinuclear [Cu2L2] molecules. These form two short Cu-O-Cu bridges enabling a medium to strong antiferromagnetic (AFM) coupling (2J: from-32 cm-1 (2) to-552 cm-1 (4)). The observed interaction's magnitude is compared with their respective Cu-O(pH)-Cu angle and Cu Cu distance. Its differentiation may be related to the phenyl rings' attached groups. Bulky t-Bu on the phenyl ring's orto position is in all cases related with a shorter Cu Cu distance, smaller AFM coupling and larger distortion of the coordination sphere's basal plane.

This work comparatively investigates structurally related Mn(II) and Zn(II) hydrazone complexes within a unified structural, computational, and biological framework. Three Mn(II) complexes, whose crystal structures have been previously reported, are examined here in detail alongside a newly synthesized and fully characterized Zn(II) analogue. Single-crystal X-ray diffraction revealed that the Zn(II) complex adopts a distorted octahedral coordination environment with an NNS donor set. Spectroscopic methods (IR, NMR and UV-Vis) confirmed ligand coordination in solution. Density functional theory (DFT) calculations showed that all complexes are thermodynamically stable in DMSO, while TDDFT calculations not only reproduced the experimental absorption energy but also resolved the band into two close-lying singlet excitations and, through NTO analysis, established their ligand-centred π → π* nature. The cytotoxic activity of the complexes was assessed against five human cancer cell lines (HeLa - cervical adenocarcinoma, A549 - lung carcinoma, MDA-MB-231 - breast adenocarcinoma, K562 - chronic myelogenous leukemia and LS 174T - colorectal adenocarcinoma) and human normal lung fibroblasts (MRC-5). The Mn(II) complexes exhibited pronounced cytotoxic effects, associated with cell cycle perturbation, apoptosis induction, and modulation of intracellular ROS levels in normal MRC-5 cells. The Zn(II) complex displayed a distinct biological profile. Antimicrobial activity was also evaluated against selected bacterial and fungal strains, and it was found that metal coordination significantly enhances activity compared to the free ligands. Overall, the results highlight comparable biological activity of Mn(II) and Zn(II) hydrazone complexes, supporting their potential as promising scaffolds for further development as antitumor and antimicrobial agents.

Four copper(II) compounds 1-4 with three aliphatic alpha,w-dicarboxylic acids (HOOC-(CH2)n-COOH; n = 2-4, H2L1-3) anions and 2-aminopyridine (L4) or 2-amino-5-methylpyridine (L5) have been isolated. Three of them show a dinuclear coordination motif [Cu(L1-2)(L4-5)2]2 1-3, while one [Cu(L3)(L4)2]n 4 reveals a polynuclear structure. A net water molecule is seen in the L5 compound 2. The dicarboxylates are coordinated bridging head to tail between the adjacent metal centres. They are forming a distorted coordination square plane CuO2N2 with two aminopyridines. The second carboxylate oxygen atom of each L1-3 occupies the axial position at significantly longer distance with respect to the equatorial CuO2N2 plane. The 2-amino group of the pyridine-based ligands L4-5 is enabling an intramolecular H-bond with the axial carboxylate oxygen atom, all in accordance with alike IR spectra of 1-4. Each dicarboxylate thus connects two copper(II) centres. Either as a double bridge in the dinuclear 1-3 or enabling a chain in the polymeric 4. A weak magnetic interaction was found only in dinuclear 1-3. It is related with both carboxylate groups of each dicarboxylate L1-3 needed for the coordination bridge and the twisted aliphatic moieties of these bridges, which do not support the magnetic coupling between metal centres.

A series of new aminomethylpyridinium hexafluoridosilicate salts with the formula (RH)2[SiF6] (where R = 2-amino-3-methylpyridine (1), 2-amino-4-methylpyridine (2), 2-amino-5-methylpyridine (3) and 2-amino-6-methylpyridine (4)) were prepared by the reaction of various methyl-substituted 2-aminopyridines with hydrogen fluoride solution of silica. The crystal packing of these ionic salts is compared with respect to the position of the methyl group on the aromatic ring. The crystal structures are dominated by the non-covalent interactions: the N–H···F hydrogen bonds and π-π interactions between aromatic rings. The potential of the corresponding ionic salts to enable supramolecular associations was investigated. Compounds 1–4 were also characterized by 1H, 19F NMR and IR spectroscopy.

Selectively deuterated electron-deficient N-containing heteroaromatic systems can enable modulation of metabolism with enhanced therapeutic efficacy in pharmaceuticals and improved properties and stability of functional materials, e.g., imaging dyes, light emitters, and catalysts. Current synthetic approaches to selectively deuterate N-heteroaromatic rings largely rely on transition metal (TM) catalysts, prone to inducing over-deuteration while posing several environmental and sustainability concerns and requiring onerous purification to remove metal traces. In this work, an alternative TM-free approach is reported based on directed ortho metalation, which employs lithium 2,2,6,6-tetramethylpiperidide (LiTMP) such as the base and D2O as a green and accessible electrophilic source of deuterium (D). Since the O-carbamate and carboxamide directing groups (DGs) can be transformed into other functional groups or cross-coupled with aromatic or aliphatic moieties, this enables a modular approach to synthesize a series of drug analogs, as exemplified by the synthesis of a precursor to momelotinib-d 1 and the key building block pyrimidine-4-carboxylic-5-d 1 acid.

5-sulfosalicylic acid (H3L) poses three potential coordination groups (carboxylic, sulfonic and hydroxylic) that can deprotonate and enable versatile coordination options with metal ions. This includes a bridging mode, a suitable way to enable stronger magnetic interactions, among adjacent metal ions. Several novel coordination compounds with 5-sulfosalicylates were synthesized and characterized. These are {[Cu(inia)(HL)(H2O)2] (H2O)2}n 1 (inia - isonicotinamide, C6H6N2O), [Zn(inia)2(HL)(H2O)2](H2O) 2, Co(inia)(HL)(H2O)5 3, {(CH6N3)2[Cu(L)(H2O)]2(2OHpy)4} 4 (2OHpy -2-hydroxypyridine, C5H5NO; CH6N3+ -guanidinium cation), and (CH6N3)Cu(L)(H2O) 5. A single crystal XRD analysis reveals structural arrangement of 1, 2 and 4. CHN and IR analyses corroborate with the structural data and propose rational formulae also for 3 and 5. A strong antiferromagnetic (AFM) coupling is found for 4 (J = -116 cm-1/ mol Cu(II)) being in agreement with a pair short monoatomic Cu center dot center dot center dot O center dot center dot center dot Cu' coordination bridges (Cu center dot center dot center dot O 1.941/ Cu'center dot center dot center dot O 1.998 angstrom) showing pseudo dimers within coordination polyanions. As no such short contacts are seen for 1, the magnetically isolated Cu(II) are present in a neutral coordination formulae, while diamagnetic Zn(II) is in 2. Additionally, a strong AFM coupling is present also in 5 (J = -126 cm-1/mol Cu(II)) with a formulae also suggesting ionic constituents as in 4. The cobalt compound 3 reveals only a small orbital contribution L within almost magnetically isolated Co(II), giving D = 56.5 cm-1, E = -0.34 cm-1, and zJ = -0.011 cm-1.

The oxidant meta-chloroperbenzoic acid (m-CPBA) is used widely for the epoxidation of alkenes, yet its efficiency is often limited under ambient conditions. This study investigates the catalytic activity of a Mn(II) salt and mononuclear Mn(II) complexes, two of which are reported here for the first time, in the epoxidation of alkenes with m-CPBA under ambient conditions. Time-resolved Raman spectroscopy is used to monitor substrate conversion, oxidant consumption, and product formation. The data reveal that simple Mn(II) salts exhibit significantly higher catalytic activity than Mn(II) complexes, indicating that ligand coordination inhibits the reactivity of the manganese center. The catalytic efficiency of Mn(II) perchlorate is particularly notable, achieving near-complete oxidation of styrene within minutes under mild conditions. Furthermore, epoxidation of a range of alkenes demonstrates that Mn(II) salts provide broad substrate scope and high selectivity. These findings suggest that simple Mn(II) salts can serve as highly efficient and cost-effective catalysts in alkene epoxidations with m-CPBA.

In this paper, three different Zn(II) complexes with (E)-2-(2-(1-(6-bromopyridin-2-yl)ethylidene)hydrazinyl)-N,N,N-trimethyl-2-oxoethan-1-aminium chloride (HLCl) have been synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR and NMR spectroscopy. All complexes are mononuclear, with the ligand (L) coordinated in a deprotonated formally neutral zwitterionic form via NNO donor set atoms. Complex 1 forms an octahedral geometry with the composition [ZnL2](BF4)(2), while complexes 2 [ZnL(NCO)(2)] and 3 [ZnL(N-3)(2)] form penta-coordinated geometry. Density functional theory (DFT) calculations were performed to enhance our understanding of the structures of the synthesized complexes and the cytotoxic activity of the complexes was tested against five human cancer cell lines (HeLa, A549, MDA-MB-231, K562, LS 174T) and normal human fibroblasts MRC-5. Additionally, antibacterial and antifungal activity of these complexes was tested against a panel of Gram-negative and Gram-positive bacteria, two fungal strains, and a yeast strain. It is noteworthy that all three complexes show selective antifungal activity comparable to that of amphotericin B. Molecular docking analysis predicted that geranylgeranyl pyrophosphate synthase, an enzyme essential for sterol biosynthesis, is the most likely target for inhibition by the tested complexes.

Two new Zn(II) complexes bearing tridentate hydrazone-based ligands with NNO or NNS donor atoms were synthesised and characterised by elemental analysis, infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies, and single crystal X-ray diffraction methods. These complexes, together with four previously synthesised analogues, having hydrazone ligands with a NNO donor set of atoms, were successfully employed as catalysts in the ketone-amine-alkyne (KA(2)) coupling reaction, furnishing tetrasubstituted propargylamines, compounds with unique applications in organic chemistry. DFT calculations at the CAM-B3LYP/TZP level of theory were performed to elucidate the electronic structure of the investigated Zn(II) complexes, excellently correlating the structure of the complexes to their catalytic reactivity.

The condensation product of 7-acetyl-6-azaindole and Girard?s T reagent ((E)-2-(2-(1-(1H-pyrrolo[2,3-c]pyridin-7-yl)ethylidene)hydrazineyl)- -N,N,N-trimethyl-2-oxoethan-1-aminium, HL ligand) was used as a ligand in the reaction with Cu(BF4)2?6H2O and NaN3. The reaction led to the formation of a binuclear Cu(II) complex containing two end-to-end (di-?-1,3-N3) azide bridges, as well as two NNO-donor hydrazone ligands, forming an axially elongated square pyramidal geometry around each Cu(II) center. This end-to-end (di- ?-1,3-N3) azide bridge binding mode has not yet been reported, in Cu(II) complexes containing the NNO-donor hydrazone ligands, which makes the structure of the complex even more interesting for further studies. The complex was characterized by elemental analysis, IR spectroscopy and X-ray crystallography, and it was found that it crystallizes in the triclinic space group P?1 with the asymmetric unit comprising one Cu(II) centre, zwitterionic ligand L, one azide (N3 -) ligand and BF4 - counter anion. Examination of antimicrobial activity of the complex shows higher antifungal and antibacterial activity towards tested Gram-positive bacteria in comparison to the hydrazone ligand, with the antifungal activity of the complex even being comparable to the activity of amphotericin B.

In this study, the properties of nickel(II) thiosemicarbazone (complex 1) and nickel(III) (complex 2) hydrazone complexes were investigated using single crystal X-ray diffraction analysis, electron paramagnetic resonance, infrared spectroscopy, UV-Vis spectroscopy, molar conductivity and Density Functional Theory (DFT) calculations. The large difference in magnetic moments led us to suspect that we had obtained nickel complexes of different oxidation states (3.5 mu B and 2.1 mu B). This was verified after recording the Electron Paramagnetic Resonance (EPR) spectra for complex 2. The g value of 2.018 is consistent with a low spin (S = 1/2) Ni(III) species. DFT calculations are in agreement with the EPR data and show a doublet spin state of complex 2 with the unpaired electron practically completely located in the first coordination sphere (76.5%). All the findings show that the studied complex have different structural and electronic properties as a function of the oxidized state of nickel. In general, nickel(III) complexes are more difficult to obtain than nickel(II) complexes due to the stability of the nickel(II) oxidation state. Considering that this is the first Ni(III) hydrazone complex to be synthesised without an oxidising agent, its importance lies in providing insight into the fundamental properties and structure of Ni(III) hydrazone complexes. This could help to improve their synthesis and further investigate their applications.

Two Co(III) complexes with condensation product of thiosemicarbazide and 2-acetylthiazole ( HL 1 ligand, ( E )-2-(1-(thiazol-2-yl)ethylidene)hydrazine-1-carbothioamide) and the condensation product of 2-acetylpyridine and Girard's P reagent ( HL 2 Cl ligand, ( E )-1-(2-oxo-2-(2-(1-(pyridin-2yl)ethylidene)hydrazinyl)ethyl)pyridin-1-ium chloride) have been synthesized and characterized based on the results of single-crystal X-ray diffraction, NMR and IR spectroscopy and elemental analysis. Cobalt(III) complex with HL 1 ligand, [Co( L 1 ) 2 ]BF 4 center dot H 2 O ( 1 ), is bis octahedral complex in which two deprotonated ligand molecules coordinate in a mer arrangement through two NNS sets of donor atoms. In cobalt(III) complex with HL 2 Cl, [Co( L 2 )(N 3 ) 3 ] ( 2 ), the ligand is coordinated in deprotonated, formally neutral, form to Co(III) ion in tridentate fashion through NNO set of donor atoms, and the other three coordination sites of a monokis octahedron are occupied by meridionally coordinated azide anions. DFT calculations were performed to elucidate coordination preferences of these ligands toward Co(III) ion. (c) 2022 Elsevier B.V. All rights reserved.

In this paper, Cu(II), Mn(II) and Zn(II) complexes with N,N,N-trimethyl-2-oxo-2-(2-(1-(thiazol-2-yl)ethylidene)hydrazinyl)ethan-1-aminium chloride (HL1Cl) were synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis and DFT calculations. In all three complexes, a ligand (L1) is coordinated in a deprotonated formally neutral zwitterionic form via NNO donor set atoms. Cu(II) and Zn(II) form mononuclear penta-coordinated complexes [CuL1(N3)(CH3OH)]BF4 and [ZnL1(N3)2], respectively, while Mn(II) forms a binuclear [Mn2L12(μ-1,1-N3)2(N3)2]·2CH3OH complex, with unusual distorted trigonal-prismatic geometry around the metal centers. The antimicrobial activity of these complexes was tested against a panel of Gram-negative and Gram-positive bacteria, two yeasts and one fungal strain. The binuclear Mn(II) complex showed antifungal activity of similar intensity to amphotericin B. Based on the results of the brine shrimp test and DPPH radical scavenging activity, the most active Cu(II) and Mn(II) complexes were selected for evaluation of cytotoxic activity against five malignant cancer cell lines (HeLa, A375, MCF7, PC-3 and A549) and one normal cell line HaCaT. Both complexes showed significant activity. It should be pointed out that the activity of the Mn(II) complex against the MCF7 breast cancer cell line is only slightly weaker than that of cisplatin, but with selectivity to the tumor cell line in comparison to normal HaCaT cells, which is non-existent in the case of cisplatin.

The reaction of N-(2-pyridyl)thiourea with CuCl2 in methanol yields four different crystalline products: yellow dimeric complex, [Cu2Cl2(?-Cl)2(L)2] (1), red polymeric complex, [Cu3Cl8L2]n (2), orange crystalline product with ionic structure, L2[CuCl4] (3), and colourless ionic compound LCl (4), where L = 2-amino-[1,2,4]thiadiazolo[2,3-a]pyridin-4-ium cation as a result of oxidative cyclization of N-(2-pyridyl)thiourea. The crystal structures of all these crystalline products have been determined by single-crystal X-ray diffraction analysis. Compound 1 involves a copper(I) ion while in 2 and 3 the copper centre is in the divalent state. 1H NMR spectra for compounds 1-3 are identical and confirm deprotonated thioamide groups of N-(2-pyridyl)thiourea and the formation of a thiadiazolopyridinium cation in solution. The hydrogen bonding and ?-? stacking interactions were investigated in the solid state. In addition, all crystalline products 1-4 exhibit also S···Cl bonding interactions which consolidate the complexes into networks. The X-ray diffraction analyses indicate the absence of other crystalline phases in the crude reaction mixture.

We have synthesized and characterized Co(II) ( 1 ), Zn(II) ( 2 ), Fe(III) ( 3 ) and Cu(II) ( 4 ) complexes of 2,2'‐[2,6‐pyridinediylbis(ethylidyne‐1‐hydrazinyl‐2‐ylidene)]bis[ N,N,N ‐trimethyl‐2‐oxoethanaminium] dichloride ( H 2 L Cl 2 ) by NMR, IR, and X‐Band EPR spectroscopy, respectively, as well as by single‐crystal X‐ray structural analysis. H 2 L Cl 2 belongs to the class of diacetylpyridine bis(hydrazone) ligands and bears two positively charged quaternary ammonium functionalities. The complexes 1 – 3 possess a pentagonal‐bipyramidal geometry, whereas 4 has square‐pyramidal geometry. Redox reactivity and SOD activity of the complexes was studied by means of electrochemical measurements in aqueous‐buffer and DMF or DMSO solutions, respectively, as well as by stopped‐flow measurements. Complexes 1 – 3 do not have SOD activity, whereas 4 exhibits a high catalytic rate constant for the superoxide dismutation, k cat = 1.73 × 10 7 m –1 s –1 (in MOPS buffer solution of pH = 7.4). The results were discussed in terms of complex redox potentials, electrostatic interactions and their spatial distribution, kinetic lability of metal centers, and stability of peroxo intermediates, respectively.

Two new Zn(II) complexes with tridentate hydrazone-based ligands (condensation products of 2-acetylthiazole) were synthesized and characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy and single crystal X-ray diffraction methods. The complexes 1, 2 and recently synthesized [ZnL3(NCS)2] (L3 = (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-aminium) complex 3 were tested as potential catalysts for the ketone-amine-alkyne (KA2) coupling reaction. The gas-phase geometry optimization of newly synthesized and characterized Zn(II) complexes has been computed at the density functional theory (DFT)/B3LYP/6–31G level of theory, while the highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO and LUMO) energies were calculated within the time-dependent density functional theory (TD-DFT) at B3LYP/6-31G and B3LYP/6-311G(d,p) levels of theory. From the energies of frontier molecular orbitals (HOMO–LUMO), the reactivity descriptors, such as chemical potential (μ), hardness (η), softness (S), electronegativity (χ) and electrophilicity index (ω) have been calculated. The energetic behavior of the investigated compounds (1 and 2) has been examined in gas phase and solvent media using the polarizable continuum model. For comparison reasons, the same calculations have been performed for recently synthesized [ZnL3(NCS)2] complex 3. DFT results show that compound 1 has the smaller frontier orbital gap so, it is more polarizable and is associated with a higher chemical reactivity, low kinetic stability and is termed as soft molecule.

Binuclear double end-on azido bridged Ni(II) complex (1) with composition [Ni2L2(mu-(1,1)-N-3)(2)(N-3)(2)]center dot 6H(2)O, (L = (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-amin) was synthesized and characterized by single-crystal X-ray diffraction method. Ni(II) ions are hexacoordinated with the tridentate heteroaromatic hydrazone-based ligand and three azido ligands (one terminal and two are end-on bridges). DFT calculations revealed that coupling between two Ni(II) centers is ferromagnetic in agreement with binuclear Ni(II) complexes with similar structures.