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A series of heteroleptic copper(II) complexes of the composition [Cu(L1–5)Cl]X, where X = ClO4 and/or PF6 and [bis(2-ethyl-di(3,5-dimethyl-1H-pyrazol-1-yl))-(6-methyl-(2-pyridylmethyl))]amine (L1), [bis(2-ethyl-di(3,5-dimethyl-1H-pyrazol-1-yl))-(3,4-dimethoxy-(2-pyridylmethyl))]amine (L2), [bis(2-ethyl-di(3,5-dimethyl-1H-pyrazol-1-yl)-(2-quinolymethyl)]amine (L3), [bis(2-ethyl-di(3,5-dimethyl-1H-pyrazolyl)-(di(3,5-dimethyl-1H-pyrazol-1-yl-methyl))]amine (L4) and [bis(2-ethyl-di(3,5-dimethyl-1H-pyrazol-1-yl)-(5-methyl-3-phenyl-1H-pyrazol-1-yl-methyl)]amine (L5), were prepared and thoroughly characterized including single-crystal X-ray diffraction technique. The in vitro cytotoxicity of complexes against A2780, A2780R, HOS and MCF-7 human cancer cell lines was evaluated using the MTT test. The results revealed that complexes [Cu(L1)Cl]PF6 (1-PF6), [Cu(L2)Cl]ClO4 (2-ClO4) and [Cu(L3)Cl]PF6 (3-PF6) are the most effective, with IC50 values ranging from 1.4 to 6.3 μM, thus exceeding the cytotoxic potential of metallodrug cisplatin (IC50 values ranging from 29.9 to 82.0 μM). The complexes [Cu(L4)Cl]PF6 (4-PF6) and [Cu(L5)Cl]PF6 (5-PF6) showed only moderate cytotoxicity against A2780, with IC50 = 53.6 μM, and 33.8 μM, respectively. The cell cycle profile, time-resolved cellular uptake, interactions with small sulfur-containing biomolecules (cysteine and glutathione), intracellular ROS production, induction of apoptosis and activation of caspases 3/7 were also evaluated in the case of the selected complexes. It has been found that the best performing complexes 1 and 2 cause cell arrest in the G2/M phase and induce apoptosis via the increase in production of ROS, dominantly due to the overproduction of superoxide.

Two penta-coordinate complexes of the general formula [Co(Ln)(NCS)]ClO4, where L1 = {bis[(3,5-dimethyl-1H-pyrazol-1-yl)ethyl]-[(3,4-dimethoxypyridin-2-yl)methyl]}amine and L2 = {bis[(3,5-dimethyl-1H-pyrazol-1-yl)ethyl]-[(4-methoxy-3,5-dimethylpyridin-2-yl)methyl]}amine, have been synthesized and thoroughly characterized. Each of the cobalt(ii) atoms is penta-coordinated in the {CoN5} donor set with a distorted square-pyramidal geometry in [Co(L1)(NCS)]ClO4·MeOH (1), while the vicinity of the central atom can be described as a distorted trigonal-bipyramidal geometry in [Co(L2)(NCS)]ClO4 (2) as revealed using the SHAPE analysis. Differences in interatomic parameters among the cobalt(ii) and donor atoms in 1 and 2 have definite impact on the magnetic features of both compounds. The complexes show an easy-axis magnetic anisotropy (D = -38.5 cm-1 for 1 and D = -8.5 for 2), and both complexes reveal a large rhombicity with E/D = 0.21 for 1 and E/D = 0.29 for 2. The ZFS parameters (g, D and E) were also calculated using CASSCF/NEVPT2 methods and they are in good agreement with those determined from experimental data. A frequency dependent out-of-phase susceptibility has been observed in external magnetic field (Bdc = 0.1 T) revealing the following parameters of slow relaxation of magnetization for 1: energy of the spin reversal barrier, Ueff = 16.0 cm-1 (Ueff/kB = 23.0 K) and the relaxation time, τ0 = 1.28 × 10-6 s. In the case of complex 2, no maxima of frequency dependent out-of-phase susceptibility have been observed and thus, the value of Ueff = 17 cm-1 has been estimated using the expression Ueff = |D| × (S2 - 1/4). It has been demonstrated that the degree of substitution and the type of substituents on the pyridyl moieties of the tripodal ligands (L1 and L2) used in these penta-coordinate cobalt(ii) complexes have significant impact on structural and magnetic features.

A series of dinuclear metal(ii)-acetato complexes: [Ni2(μ-L(Cl)O)(μ2-OAc)2](PF6)·3H2O (1), [Ni2(μ-L(Cl)O)(μ2-OAc)2](ClO4)·CH3COCH3 (2), [Cu2(μ-L(Cl)O)(μ2-OAc)(ClO4)](ClO4) (3), [Cu2(μ-L(Cl)O)(OAc)2](PF6)·H2O (4), [Zn2(μ-L(Cl)O)(μ2-OAc)2](PF6) (5) and [Mn2(L(Cl)-O)(μ2-OAc)2](ClO4)·H2O (6), where L(Cl)O(-) = 2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-chlorophenolate, were synthesized. The complexes were structurally characterized by spectroscopic techniques and single crystal X-ray crystallography. Six-coordinate geometries with doubly bridged acetato ligands were found in Ni(ii), Zn(ii) and Mn(ii) complexes 1, 2, 5 and 6, whereas with Cu(ii) complexes a five-coordinate species was obtained with 4, and mixed five- and six-coordinate geometries with a doubly bridged dimetal core were observed in 3. The magnetic properties of complexes 1-4 and 6 were studied at variable temperatures and revealed weak to very weak antiferromagnetic interactions in 1, 2, 4 and 6 (J = -0.55 to -9.4 cm(-1)) and ferromagnetic coupling in 3 (J = 15.4 cm(-1)). These results are consistent with DFT calculations performed at the B3LYP/def2-TZVP(-f) level of theory. Under physiological conditions, the interaction of the dinculear complexes 1-5 with supercoiled plasmid ds-DNA did not show any pronounced nuclease activity, but Ni(ii) complexes 1 and 2 revealed a strong ability to unwind the supercoiled conformation of ds-DNA. The mechanistic studies performed on the interaction of the Ni(ii) complexes with DNA demonstrated the important impact of the nickel(ii) ion in the unwinding process. In combination with the DNA study, the phosphatase activity of complexes 1, 3, and 5 was examined by the phosphodiester hydrolysis of bis(2,4-dinitrophenol)phosphate (BDNPP) in the pH range of 5.5-10.5 at 25 °C. The Michaelis-Menten kinetics performed at pH 7 and 10.7 showed that catalytic efficiencies kcat/KM (kcat = catalytic rate constant, KM = substrate binding constant) decrease in the order: Ni(ii), 1 > Zn(ii), 5 > Cu(ii), 3. A similar trend was also observed with the turnover numbers at pH = 7. The results are discussed in relation to the coordination geometry and nature of the metal center as well as the steric environment imposed by the compartmental phenoxido ligand.

The use of 6-methylpyridine-2-carbaldehydeoxime ligand (6-mepaoH), in nickel(II) chemistry has been investigated and three new clusters isolated in mild conditions. Depending on the nature of the metal starting salts and the reaction conditions, the Ni(II)/6-mepaoH system has provided access to the complexes [Ni(6)(O(2)CPh)(6)(6-mepao)(6)] (1), [Ni(6)(O(2)CMe)(6)(6-mepao)(6)] (2) and [Ni(5)(3-Cl-BzO)(4)(6-mepao)(4)(6-mepaoH)(2)(N(3))(2)] (3), where 3-Cl-BzO(-) is the 3-chlorobenzoate anion. Compounds 1 and 2 are two new members of the [Ni(6)(O(2)C-R)(oximato)(6)] family of hexanuclear complexes whereas 3 exhibits an unusual irregular bowtie topology including end-on azido bridges. The structures of the three compounds have been determined by single-crystal X-ray crystallography. Variable-temperature dc magnetic susceptibility studies were carried out for 1-3. The data indicate antiferromagnetic exchange for complexes 1 and 2 and ferrimagnetic interaction for complex 3.

A hybrid organic-inorganic chain compound of the family Mn(II)-bpa-(NCO) is presented. It contains, unusually, five different dispositions for the bpa [1,2-bis(4-pyridyl)ethane] ligand. Water molecules and free bpa ligands occupy the voids of the structure. The compound shows significant antiferromagnetic-type interactions as a consequence of different exchange pathways.

New monodimensional Co(II)/azido systems with unusual topological ferrimagnetic response have been characterised.

The syntheses, structural characterization, and magnetic behavior of four new copper(II) complexes derived from tert-butylphosphonic acid and di-2-pyridyl ketone with formulae [Cu{(py)(2)C(OH)(2)}](C(4)H(9)PO(3)H)(2).(H(2)O)(2) (1), [Cu(2)(mu(2)-C(4)H(9)PO(3)H){(py)(2)C(OCH(2)CH(3))O}(mu(2)-NO(3))(NO(3))(H(2)O)](n).(H(2)O)(n) (2), [Cu(4)(mu(2)-C(4)H(9)PO(3)H)(2)(mu(4)-C(4)H(9)PO(3))(2){(py)(2)C(OCH(3))O}(2)].2H(2)O (3) and Na[Cu(6)(mu(3)-C(4)H(9)PO(3))(3){(py)(2)C(OCH(3))O}(3)(mu(6)-NO(3))(NO(3))(3)] (4) (C(4)H(9)PO(3)H(2) = tert-butylphosphonic acid, (py)(2)C(OH)(2) = bis(2-pyridyl)methanediol, {(py)(2)C(OCH(2)CH(3))O}(-) = bis(2-pyridyl)ethoxymethanolato {(py)(2)C(OCH(3))O}(-) = bis(2-pyridyl)methoxymethanolato, are reported. 1 is a mononuclear compound, with tert-butylhydrogenphosphonate in the anionic form. 2 is a nitrate bridged monodimensional compound with 2.110 tert-butylhydrogenphosphonate bridging ligands. 3 is a tetranuclear compound with 2.110 tert-butylhydrogenphosphonate and 3.111 tert-butylphosphonate bridging ligands and 4 is a hexanuclear compound with 3.111 tert-butylphosphonate bridging ligands. The magnetic properties of 2-4 are reported.

The coordination polymers [(Cu(N(3))(2))(2)Cu(N(3))(2)(methylpyrazine)(2)](n) 1 and [Cu(4-bromopyridine)(N(3))(2)](n) 2, were prepared from NaN(3), Cu(NO(3))(2).3H(2)O and nitrogen-containing heterocycles. 1 contains a three- and four-connected 3D (4.10(2))(2)(4(2).10(4))-dmd-net based on tetrahedral and trigonal planar nodes, whereas 2 is a sheet-structure formed by a uninodal three-connected 8(2).4 2D-net with additional BrBr (mean 3.903(2) A) and BrN(azide) (3.035(5) A) contacts. Both compounds contain end-on-type azide bridges, and 2 has in addition one end-to-end bridge as well. The corresponding magnetic interactions are J(1,2) = +14.9(6) cm(-1) for the end-on azido interactions in 1 with an additional -1.7 cm(-1) coupling through the pyrazine, and J(1) = 36(6) cm(-1) for the end-on azido interactions and J(2) = 2.5(1) cm(-1) for the orthogonal end-to-end azido interactions found in 2.

Several new MnII compounds with X-phenylcyanamido (Xpcyd) and 2,2′-bipyrimidine (2,2′-bpm) bridging ligands of formula [Mn(pcyd)(MeOH)(μ-pcyd)(μ-2,2′-bpm)0.5]n (1), [Mn(3-Clpcyd)(MeOH)(μ-3-Clpcyd)(μ-2,2′-bpm)0.5]n (2), (μ-4-Clpcyd)2[Mn(4-Clpcyd)(H2O)(2,2′-bpm)]2 (3) and [Mn(3-Fpcyd)(MeOH)(μ-3-Fpcyd)(μ-2,2′-bpm)0.5]n (4) have been synthesised and characterised. The one-dimensional compound [Mn(pcyd)(MeOH)(μ-pcyd)(μ-2,2′-bpm)0.5]n (1) crystallises in the triclinic system, P space group and the dinuclear compound (μ-4-Clpcyd)2[Mn(4-Clpcyd)(H2O)(2,2′-bpm)]2 (3) crystallises in the orthorhombic system, P212121 space group. The two compounds contain the unusual end-to-end cyanamide bridge and give supramolecular 2-D networks by means of H-bonds. Susceptibility measurements on compounds 1–4 reveal moderate antiferromagnetic coupling in all cases. Coupling constants related to the phenylcyanamido bridges are compared with the superexchange model recently proposed for ligands of this kind.