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A palladium complex of non-innocent ligand a was synthesized, and characterized by IR, UV-Vis, 1H and 13C NMR spectroscopies and elemental analysis.

Adenylate kinases (AK) play a pivotal role in the regulation of cellular energy. The aim of our work was to achieve the overproduction and purification of AKs from two groups of bacteria and to determine, for the first time, the comprehensive biochemical and kinetic properties of adenylate kinase from Gram-negative Aquifex aeolicus (AKaq) and Gram-positive Geobacillus stearothermophilus (AKst). Therefore we determined KMand Vmaxvalues, and the effects of temperature, pH, metal ions, donors of the phosphate groups and inhibitor Ap5A for both thermophilic AKs. The kinetic studies indicate that both AKs exhibit significantly higher affinity for substrates with the pyrophosphate group than for adenosine monophosphate. AK activation by Mg2+and Mn2+revealed that both ions are efficient in the synthesis of adenosine diphosphate and adenosine triphosphate; however, Mn2+ions at 0.2–2.0 mmol/L concentration were more efficient in the activation of the ATP synthesis than Mg2+ions. Our research demonstrates that zinc ions inhibit the activity of enzymes in both directions, while Ap5A at a concentration of 10 µmol/L and 50 µmol/L inhibited both enzymes with a different efficiency. Sigmoid-like kinetics were detected at high ATP concentrations not balanced by Mg2+, suggesting the allosteric effect of ATP for both bacterial AKs.

The six-coordinated bis-o-iminosemiquinone complex, NiL2BIS, in which LBIS is the o-iminosemiquinone 1-electron oxidized form of the tridentate o-aminophenol benzoxazole-based ligand H2LBAP, was synthesized and characterized. The crystal structure of the complex reveals octahedral geometry with a NiN4O2 coordination sphere in which Ni(II) has been surrounded by two tridentate LBIS ligands. This compound exhibits (SNi = 1) with both spin and orbital contribution to the magnetic moment and antiferromagnetic coupling between two electrons on two LBIS ligands which results in a triplet spin ground state (S = 1). The electronic transitions and the electrochemical behavior of this open-shell molecule are presented here, based on experimental observations and theoretical calculations. The electrochemical behavior of NiL2BIS was investigated by cyclic voltammetry and indicates ligand-centered redox processes. Three-component coupling of aldehydes, amines and alkynes (A3-coupling) was studied in the presence of the NiL2BIS complex, and the previously reported four-coordinated bis-o-iminosemiquinone NiL2NIS. Furthermore, among these two o-iminobenzosemiquinonato(1−) complexes of Ni(II) (NiL2NIS and NiL2BIS), NiL2NIS was found to be an efficient catalyst in A3-coupling at 85 °C under solvent-free conditions and can be recovered and reused for several cycles with a small decrease in activity.

The platinum(II) complexes of general formula [PtCl2(dstp)(S-donor)] were dstp 5,7-dimethyl-1,2,4-triazolo[1,5-a]-pyrimidine (dmtp), 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp), 5-methyl-7-isobutyl-1,2,4-triazolo[1,5-a]pyrimidine (ibmtp) or 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine (dptp), whereas S-tetrahydrothio-phene-1-oxide (TMSO) or diphenyl sulfoxide (DPSO) were synthesized in a one-pot reaction. Here, we present experimental data (1H, 13C, 15N, 195Pt NMR, IR, X-ray) combined with density functional theory (DFT) computations to support and characterize structure–spectra relationships and determine the geometry of dichloride platinum(II) complexes with selected triazolopyrimidines and sulfoxides. Based on the experimental and theoretical data, factors affecting the stability of platinum(II) complexes have been determined.

A series of new chiral benzisoselenazol-3(2H)-ones and their corresponding diselenides bearing an o-amido function substituted on the nitrogen atom with various aliphatic and aromatic moieties were synthesized. All derivatives representing pairs of enantiomers or diastereoisomers were obtained to thoroughly evaluate the three-dimensional structure–activity correlation. First, bensisoselenazol-3(2H)-ones were synthesized by reacting 2-(chloroseleno)benzoyl chloride with an appropriate enantiomerically pure amine. Then, the Se–N bond was cleaved by a reduction–oxidation procedure using sodium borohydride and then air oxidation to obtain the corresponding diselenides. All derivatives were tested as antioxidants and anticancer agents. In general, the diselenides were more reactive peroxide scavengers, with the highest activity observed for 2,2′-diselenobis[N-(1S,2S)-(-)-trans-2-hydroksy-1-indanylbezamide]. The most cytotoxic derivative towards human promyelocytic leukemia HL-60 and breast cancer MCF-7 cell lines was N-[(1S,2R)-(-)-cis-2-hydroksy-1-indanyl]-1,2-benzizoselenazol-3(2H)-one. The structure–activity relationship of the obtained organoselenium derivatives was discussed.

In this study, a novel Mn(III)–Schiff base complex was synthesized and characterized. The structure of this complex was determined to be a deformed octahedral coordination sphere by single-crystal X-ray diffraction analysis. The Mn(III)–Schiff base complex was supported on silica-coated iron magnetic nanoparticles via axial coordination by one-step complex anchoring to produce a heterogenized nanocatalyst. After this, the complex was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), and powder X-ray diffraction (XRD). Moreover, atomic absorption spectroscopy was used to determine the amount of the loaded metal. The heterogenized nanocatalyst effectively catalyzed the oxidation of a broad range of sulfides and alkenes with H2O2 in the presence of a glassy carbon electrode, applying voltage to the reaction mixture. The results showed that the application of a potential to the reaction mixture could significantly decrease the reaction time when compared with the case of similar chemical oxidation reactions. In addition, an excellent value of turnover frequency (17 750 h−1) was achieved for the electrochemical oxidation of styrene. Moreover, the nanocatalyst showed good recoverability without significant loss of its activity within six successive runs in the electrochemical oxidation of methyl phenyl sulfide and cyclooctene. The electrochemical properties and stability of Fe3O4@SiO2-[MnL(OAc)] were investigated by cyclic voltammetry measurements and chronoamperometry technique.

The synthesis and characterization of a new Cu(II) complex, LNIS2CuII (LNIS = o-iminobenzosemiquinone), are reported. X-ray crystallography studies showed that two o-iminobenzosemiquinone radicals form a distorted square-planar geometry around the Cu(II) center of LNIS2CuII. Magnetic measurements revealed the paramagnetic character of the complex caused by the presence of three unpaired electrons located on the o-iminobenzosemiquinonate ligands and the CuII center. Magnetochemical experiments, and EPR and DFT studies prove that the ground state of the complex is a doublet, which is consistent with the ferromagnetic coupling between Cu(II) and o-iminobenzosemiquinone centers and stronger antiferromagnetic coupling between the iminobenzosemiquinone moieties. The ligand-centered redox reactions of the complex were studied by cyclic voltammetry. Aerobic oxidation of alcohols to aldehydes with TEMPO was studied in the presence of LNIS2CuII. Furthermore, LNIS2CuII was found to be an efficient catalyst in homo-coupling of terminal alkynes.

A new Ni(II) complex, was synthesized from the reaction of a non-innocent o-aminophenol ligand, and Ni(OAc)2. The crystal structure of NiIIL2NIS (in which, IS stands for iminosemiquinone radical ligand with cyanide (shown by N in NIS) substituent on phenolate rings) exhibits the square planar environment of Ni(II). The complex has been crystalized in the monoclinic system and Ni(II) was surrounded by two oxygen and two nitrogen atoms of two ligands. Variable-temperature magnetic susceptibility measurement for crystalline samples of complex shows the effective magnetic moment per molecule (μeff) of near zero and the diamagnetic nature of the complex (S = 0) which emphasize that strong antiferromagnetic coupling prevailed between the two unpaired electrons of LNIS ligands and Ni(II) high spin electrons. The complex is EPR silent which confirms the diamagnetic character of the Ni(II) complex. Electrochemical measurement (CV) indicates the redox-active character of ligand and metal. NiIIL2NIS complex proved to be effective for free metal- or base counterpart homocoupling of phenyl acetylene at room temperature. To the best of our knowledge, this is the first example of using Ni(II) complex without using any reducing agent due to the promotion ancillary effect of non-innocent o-aminophenol ligand which acts as an “electron reservoir” and can reversibly accept and donate electrons in the catalytic cycle. The theoretical calculation confirms the magnetostructure, electronic spectrum and confirmed the suggested mechanism of phenyl acetylene homocoupling with emphasis on the role of non-innocent ligand electro-activity and the effect of ligand substituent on the efficiency and stability of the complex.

New ligands obtained in the reaction of o-phenylenediamine and series of aldehydes (L1-L5) were synthesized. Molecular architecture of the synthesized ligands L1-L5 has been determined by the X-ray crystal structure analysis. 1H NMR NOE diff. spectra (differential Nuclear Overhauser Effect) of ligands indicate that they have different conformation in the solution in comparison to the solid state (crystal structure). The substrates molar ratio and the reaction time allowed the controlled synthesis of mono substituted o-phenylenediamine or benzimidazole derivatives with no catalyst used. For all compounds the relatively high fluorescence efficiency was observed in the range 0.41–0.83 in MeCN and 0.48–0.96 in CH2Cl2 solution. Based on DFT calculations the fluorescence mechanism was associated with HOMO→LUMO transition between aromatic rings and benzimidazole moieties.

Adenylate kinases (AK) play a pivotal role in the regulation of cellular energy. The aim of our work was to achieve the overproduction and purification of AKs from two groups of bacteria and to determine, for the first time, the comprehensive biochemical and kinetic properties of adenylate kinase from Gram-negative

Within the broad group of Fe non-heme oxidases, our attention was focused on the catechol 1,2- and 2,3-dioxygenases, which catalyze the oxidative cleavage of aromatic rings. A large group of Fe complexes with N/O ligands, ranging from N3 to N2O2S, was developed to mimic the activity of these enzymes. The Fe complexes discussed in this work can mimic the intradiol/extradiol catechol dioxygenase reaction mechanism. Electronic effects of the substituents in the ligand affect the Lewis acidity of the Fe center, increasing the ability to activate dioxygen and enhancing the catalytic activity of the discussed biomimetic complexes. The ligand architecture, the geometric isomers of the complexes, and the substituent steric effects significantly affect the ability to bind the substrate in a monodentate and bidentate manner. The substrate binding mode determines the preferred mechanism and, consequently, the main conversion products. The preferred mechanism of action can also be affected by the solvents and their ability to form the stable complexes with the Fe center. The electrostatic interactions of micellar media, similar to SDS, also control the intradiol/extradiol mechanisms of the catechol conversion by discussed biomimetics.

Statins are the most effective cholesterol-lowering drugs. They also exert many pleiotropic effects, including anti-cancer and cardio- and neuro-protective. Numerous nano-sized drug delivery systems were developed to enhance the therapeutic potential of statins. Studies on possible interactions between statins and human proteins could provide a deeper insight into the pleiotropic and adverse effects of these drugs. Adenylate kinase (AK) was found to regulate HDL endocytosis, cellular metabolism, cardiovascular function and neurodegeneration. In this work, we investigated interactions between human adenylate kinase isoenzyme 1 (hAK1) and atorvastatin (AVS), fluvastatin (FVS), pravastatin (PVS), rosuvastatin (RVS) and simvastatin (SVS) with fluorescence spectroscopy. The tested statins quenched the intrinsic fluorescence of hAK1 by creating stable hAK1-statin complexes with the binding constants of the order of 104 M−1. The enzyme kinetic studies revealed that statins inhibited hAK1 with significantly different efficiencies, in a noncompetitive manner. Simvastatin inhibited hAK1 with the highest yield comparable to that reported for diadenosine pentaphosphate, the only known hAK1 inhibitor. The determined AK sensitivity to statins differed markedly between short and long type AKs, suggesting an essential role of the LID domain in the AK inhibition. Our studies might open new horizons for the development of new modulators of short type AKs.

We investigate the emission properties of four organic dyes containing a strong electron-donating N(CH3)2 group and an NBF2O-bearing heterocyclic moiety acting as the electron-accepting group. The four studied compounds differ in the number and positions of the fused benzo rings included in the heterocyclic moiety. They exhibit strong emission in solution, with fluorescence quantum yields (Φf) systematically exceeding 0.8 at least in one of the solvents used, regardless of the benzannulation architecture. The strong dipolar character, achieved by substitution with the N(CH3)2 group and benzannulation, enhances the photoinduced charge transfer and appears to be an effective strategy to tune the photophysical properties of these dyes in solution. Indeed, red-shifted absorption spectra are obtained without deteriorating the emission properties. However, the present joint theory–experiment study clearly demonstrates that such a molecular design is not effective for solid-state applications, as only one derivative still exhibits significant emission in the crystalline form, namely the most compact one. We show that the combination of benzannulation in the presence of the strong amino donor leads to substantial changes in crystal packing and that a different network of intermolecular interactions can be found in the crystal. More specifically, going from the parent compound to its benzannulated derivatives induces a stronger π⋯π stacking combined with multiple CH⋯π interactions involving the fused benzo rings and the hydrogen atoms of the dimethylamino group, which impedes efficient emission of the crystals.

The six-coordinated bis

Herein, we present dicarboxylate platinum(II) complexes of the general formula [Pt(mal)(DMSO)(L)] and [Pt(CBDC)(DMSO)(L)], where L is dbtp 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine) or ibmtp (7-isobutyl-5-methyl-1,2,4- triazolo[1,5-a]pyrimidine), as prospective prodrugs. The platinum(II) complexes were synthesized in a one-pot reaction between cis-[PtCl2(DMSO)2], silver malonate or silver cyclobutane-1,1-dicarboxylate and triazolopyrimidines. All platinum(II) compounds were characterized by FT-IR, and 1H, 13C, 15N and 195Pt NMR, and their square planar geometries with one monodentate N(3)-bonded 5,7-disubstituted-1,2,4-triazolo[1,5-a]pyrimidine, one S-bonded molecule of dimethyl sulfoxide and one O,O-chelating malonato (1, 2) or O,O-chelating cyclobutane-1,1-dicarboxylato (3, 4) was determined. Additionally, [Pt(CBDC)(dbtp)(DMSO)] (3) exhibited (i) substantial in vitro cytotoxicity against the lung adenocarcinoma epithelial cell line (A549) (IC50 = 5.00 &micro, M) and the cisplatin-resistant human ductal breast epithelial tumor cell line (T47D) (IC50 = 6.60 &micro, M), and (ii) definitely exhibited low toxicity against normal murine embryonic fibroblast cells (BALB/3T3).

We report a new mononuclear molybdenum(iv) complex, MoOL

A new Ni(ii) complex, was synthesized from the reaction of a non-innocent

In order to investigate photophysical properties and crystallization medium effects, three Cu complexes, [CuI(PCy3)]2 (1), [Cu(I)(PPh2Me)]4 (2), and [Cu4(I)4(PPh2py)2] (3) were prepared and characterized using single crystal X-ray crystallography, solid state NMR, UV–Vis, and IR spectroscopy. In 1, as previously reported, Cu2I2 core is a square dimer with alternating copper and iodides positioned in the corners. Each copper atom is surrounded by two bridging iodides and a terminal tricyclohexylphosphine ligand. The cluster 2 adopts a cubane-like Cu4I4 core, while in cluster 3 (as thf solvate) a Cu4I2 distorted octahedral core is decorated with two bridging iodides and two chelating P^N ligands. The solid state 31P NMR analysis showed the presence in the powder of several polymorphs, the most abundant of which being, in the case of 2, the cubane-like structure resolved by XRD methods, and in the case of 3, a butterfly structure, different from that found for 3·thf. The solid state blue photoluminescence intensity in 1 is dependent upon its poly- or single-crystallinity. While dimer 1 in polycrystalline form is a stronger blue light emitter under 254 nm light irradiation than in 365 nm, in single crystalline phase it shows a similar higher intensity blue luminescence under lower energy light (365 nm) irradiation. On the other hand, clusters 2 and 3 do not show phase-dependent luminescence intensity variation. Time-dependent Density Functional Theory (TD-DFT) showed that the emission in 1 and 3 is assigned to a mixed metal to ligand and halide to ligand charge transfer, (X + M)LCT. In 2, a dual emission band at low temperature was observed which was attributed to 3CC (LE band) and 3XLCT (HE band). Thermochromism and mechanochromism of complexes 1–3 were also investigated.

6-Methoxy-2-[(E)-Aryliminomethyl]-phenol (Aryl = Phenyl; 2,6-dimethyl; 2,6-diisopropylphenyl; 2,6-dichlorophenyl), comprising L1–L4 ligands, and palladium complexes [Pd(Ln)2, n = 1–4] have been synthesized. The geometries of the [Pd(Ln)2] complexes were derived from single X-ray crystallography experiments. The central Pd(II) ion is four-coordinated and surrounded by N2O2 environment, adopting a square planar geometry. The ligand is bidentate, coordinating via imine nitrogen and phenolate oxygen atoms to the metal center. Analysis of the valence geometry within the phenolate rings suggests that in all complexes, the O1–C1 has a double bond character. FT-IR, 1H, 13C NMR and single X-ray crystal structures were reported. The cytotoxicity effect of four Pd(II) complexes was assessed on three cancerous cell lines: MCF-7 (breast carcinoma), A549 (lung carcinoma) and SKOV3 (ovarian carcinoma) and compared with that for cis-platin. One out of four metal complexes, Pd(L1)2, exhibited the highest anti-proliferative activity on three investigated cancerous cells lines which is more effective than cis-platin. The results showed that this complex could effectively induce apoptotic death in cancerous cells, probably due to direct interaction by cellular DNA.

In the present work, the synthesis and characterization of a novel binuclear oxo-bridged iron(III) complex, (FeLAPIP)2O, where LAPIP is the deprotonated form of a tetradentateo-aminophenol-iminopyridine ligand, is described. The iron complex was characterized using different techniques including X-ray crystallography, infrared spectroscopy, UV-Vis, magnetic susceptibility and cyclic voltammetry. The X-ray structure analysis revealed that in the structure of the (FeLAPIP)2O complex, each iron(III) is coordinated in a distorted square pyramidal arrangement by an oxo group, three amine nitrogens and one oxygen atom of the o-aminophenolate ligand. The variable-temperature magnetic measurement exhibits strong antiferromagnetic coupling between two iron(III) centers. Cyclic voltammetry measurements showed two kinds of quasireversible events, suggesting the formation of a phenoxyl radical species in the region of the anodic peaks and a metal-centered redox (FeIII/FeII) process at low potential. The catalytic activity of this Fe-complex was evaluated in coupling of 2-aminophenol and benzyl alcohols for the one-pot synthesis of benzoxazoles. The catalyst system showed high catalytic activity in this transformation and benzoxazole derivatives were obtained in good to excellent yields. tert-Butyl hydroperoxide was used as an oxidant and 1.2 mol% of catalyst was needed to accomplish the reaction in water as the green solvent.

Au(III) chloride compounds with 7,8-benzoquinoline (bqn) – [Au(bqn)Cl3] and [Au(bqn∗)Cl2] (bqn∗ being deprotonated, at the C(10) carbon, monoanionic form of bqn) were studied by 1H–13C, 1H–15N HMQC and HMBC–NMR. 1H, 13C and 15N coordination shifts were discussed in relation to the molecular structures, revealing characteristic variability patterns. Analogous NMR measurements were performed for the new (bqnH+)2(AuCl4−)Cl− salt, studied also by single crystal X-ray diffraction. All compounds exhibited fluorescence.

The crystal and molecular structures and magnetic properties of two new complexes (HMepy)2[CuCl4]·2H2O, 2, and (H2Me2ppz)[CuCl4], 3, formed by tetrachlorocuprate(II) anions and organic heterocyclic cations, bis(3-amino-2-chloro-5-methylpyridinium) (HMepy) and trans-2,5-dimethylpiperazinium (H2Me2ppz), respectively, have been determined by the analysis of their X-ray diffraction data, magnetic susceptibility behaviour and EPR spectral parameters. These characteristics differentiate the [CuCl4]2− anions in 2 and 3 as well as that previously reported in (H2bipip)[CuCl4]·H2O, 1, (bipip = 4,4′-bipiperidine) (Tuikka et al., CrystEngComm, 2013, 15, 6177; Wikaira et al., J. Coord. Chem., 2016, 69(1), 57). The present study reveals a significant effect of the organic cations on the geometry and magnetic properties of the [CuCl4]2− anions caused evidently by the changes in the crystal packing structure. A characteristic relationship was observed between the average cis-angles around the Cu(II) ions in [CuCl4]2− for 1–3, affected by the Cu(II) coordination geometry, and g-tensor components derived from the EPR spectra, a measure of interaction of copper(II) unpaired electrons in the [CuCl4]2− anions with an external magnetic field. The magneto-structural correlations revealed weak antiferromagnetic exchange interactions between the [CuCl4]2− anions transmitted by different pathways.

New silver complexes with ligands obtained from 2(2-pirydyl)ethylamine (epy) or o-phenylenediamine and series of aldehydes were obtained and characterized by their crystalline, molecular and spectroscopic (UV-Vis, fluorescence, IR, NMR) features. Molecular architecture of the synthesized complexes [Ag2(epy(5-Brthca))2(NO3)2] 1 and [Ag(bzim-anthr)2]+NO3−2 has been determined by X-ray crystal structure analysis. 1H NMR NOE diff. spectra of Ag complexes reveal different ligand conformations in the solution and the solid state (crystal structure). Thin (13–113 nm average thickness), homogenous layers of the studied silver(I) complexes were obtained by the spin coating method. The new materials were also characterized with AFM, SEM/EDX and ellipsometry. Calculated band-gap energies related to conformational transitions in layers of complexes 3, 1 and 2 on Si(111) were 2.83 ± 0.02 eV (438 ± 3 nm), 2.90 ± 0.01 eV (428 ± 2 nm) and 2.95 ± 0.02 eV (420 ± 3 nm), respectively. The fluorescence bands of layers observed in the range 470–580 nm revealed significant intensity and were bathochromically shifted in comparison with those observed for the complexes solutions. Influence of polarity of the solvent on fluorescence properties of the obtained complexes was studied. The highest quantum yield of the fluorescence was achieved in methylene chloride for 2 with ϕ2 = 0.52 (λex = 335–385 nm) and is related to the anthracene moiety.

Tropical diseases currently constitute a major health problem and thus a challenge in the field of drug discovery. The current treatments show serious disadvantages due to cost, toxicity, long therapy duration and resistance, and the use of metal complexes as chemotherapeutic agents against these ailments appears to be a very attractive alternative. Herein, we describe three newly synthesized ruthenium complexes with a bioactive molecule, the purine analogue 5,6,7-trimethyl-1,2,4-triazolo[1,5- a ]pyrimidine (tmtp): cis,fac -[RuCl 2 (dmso) 3 (tmtp)] ( 1 ), mer -[RuCl 3 (dmso)(H 2 O)(tmtp)]·2H 2 O ( 2 ) and fac,cis -[RuCl 3 (H 2 O)(tmtp) 2 ] ( 3 ). Their structures were characterized using X-ray and spectroscopic methods (IR, NMR or EPR). The stability of the synthesized complexes 1 – 3 in various buffered solutions (pH = 3–7.4) was monitored using conventional and stopped-flow techniques. The in vitro antiproliferative activity of all ruthenium complexes against promastigote forms of Leishmania spp . ( L. infantum , L. braziliensis , and L. donovani ) and epimastigote forms of Trypanosoma cruzi was investigated. Notably, the results showed that the activity of 1 against L. brasiliensis was more than three-fold higher than that of glucantime, and 1 showed no appreciable toxicity towards J774.2 macrophages. Additionally, 2 displayed even 141-fold lower toxicity against host cells than glucantime, demonstrating significantly higher selectivity than the reference drug. Therefore, 1 and 2 appear to be excellent candidates for further development as potential drugs for the effective treatment of leishmaniasis and Chagas disease. All novel complexes were also shown to be potent inhibitors of Fe-SOD in the studied species, while their effects on human CuZn-SOD were very low.