salicylates and salophen

In this perspective, we discuss iron-complexes as drug candidates that are promising alternatives to conventional platinum-based chemotherapies owing to their broad range of reactivities and to the targeting of different biological systems. Breakthroughs in the comprehension of iron complexes' structure-activity relationship contributed to the clarification of their metabolization pathways, sub-cellular localization and influence on iron homeostasis, while enlightening the primary molecular targets of theses likely multi-target metallodrugs. Both the antiproliferative activity and elevated safety index observed among the family of iron complexes showed encouraging results as per their therapeutic potential and selectivity also with the aim of reducing chemotherapy side-effects, and facilitated more pre-clinical investigations. The purpose of this perspective is to summarize the recent advances that contributed in unveiling the intricate relationships between the structural modifications on iron-complexes and their reactivity, cellular trafficking and global mechanisms of action to broaden their use as anticancer drugs and advance to clinical evaluation.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Coordination Complexes; Drug Screening Assays, Antitumor; Ferrous Compounds; Humans; Iron; Ligands; Molecular Targeted Therapy; Pyridines; Salicylates; Structure-Activity Relationship

Zn-salophen complexes are a promising class of fluorescent chemosensors for nucleotides and nucleic acids. We have investigated, by means of steady state UV-Vis, ultrafast transient absorption, fluorescence emission and time dependent density functional theory (TD-DFT) the behavior of the excited states of a salicylidene tetradentate Schiff base (Sal), its Zn(II) coordination compound (Zn-Sal) and the effect of the interaction between Zn-Sal and adenosine diphosphate (ADP). TD-DFT shows that the deactivation of the excited state of Sal occurs through torsional motion, due to its rotatable bonds and twistable angles. Complexation with Zn(II) causes rigidity so that the geometry changes in the excited states with respect to the ground state structure are minimal. By addition of ADP to a freshly prepared Zn-Sal ethanol solution, a longer relaxation constant, in comparison to Zn-Sal, was measured, indicative of the interaction between Zn-Sal and ADP. After a few days, the Zn-Sal-ADP solution displayed the same static and dynamic behavior of a solution containing only the Sal ligand, demonstrating that the coordination of the ADP anion to Zn(II)leads to the demetallation of the Sal ligand. Fluorescence measurements also revealed an enhanced fluorescence at 375 nm following the addition of ADP to the solution, caused by the presence of 2,3-diamino naphthalene that is formed by demetallation and partial decomposition of the Sal ligand. The efficient fluorescence of this species at 375 nm could be selectively detected and used as a probe for the detection of ADP in solution.

Topics: Adenosine Diphosphate; Ligands; Salicylates; Zinc

Topics: Gallium; Heme; Humans; Iron; Pseudomonas aeruginosa; Salicylates

The salophen copper(II) complex was successfully used for the efficient synthesis of new 1,2,3-triazoles based on the naphthalene-1,4-dione scaffold. The reaction of 2-chloro-3-(prop-2-yn-1-yloxy)naphthalene-1,4-dione or 2,3-bis(prop-2-yn-1-yloxy)naphthalene-1,4-dione with aromatic azides in the presence of a low copper catalyst (loading 1 mol-%) afforded 2-chloro-3-[(1-phenyl-1H-1,2,3-triazol-4-yl)methoxy]naphthalene-1,4-dione or 2,3-bis[(1-phenyl-1H-1,2,3-triazol-4-yl)methoxy]naphthalene-1,4-dione, respectively. The advantages of these reactions are short reaction times, high-to-excellent reaction yields, operational simplicity, and mild experimental conditions. The new 1,2,3-triazoles obtained were screened for their in vitro antibacterial activities and were subjected to molecular docking studies.

Topics: Anti-Bacterial Agents; Click Chemistry; Coordination Complexes; Copper; Hydrogen Bonding; Hydrophobic and Hydrophilic Interactions; Microbial Sensitivity Tests; Molecular Docking Simulation; Naphthalenes; Salicylates; Thermodynamics; Triazoles

Control over spin states at the single molecule level is a key issue in the emerging field of molecular spintronics. Here, we explore the chemical adsorption effect on the magnetic and spin-transport properties of individual magnetic molecule by performing extensive density functional theory calculations in combining with non-equilibrium Green's function method. Theoretical results clearly reveal that the molecular magnetic moment of Mn-salophen can be effectively tuned by adsorbing F and CO on the central Mn cation, while the adsorbed NO molecule quenches the molecular magnetic moment. Without chemical adsorption, the currents through Mn-salophen molecular junction just show a little distinction for two spin channels, which agrees well with previous investigation. Remarkably, the conductive channel can be switched from the spin-up electrons to the spin-down electrons via adsorbing F and CO, respectively, and the corresponding two Mn-salophen molecular junctions with chemical modifications display nearly perfect spin-filtering effect. The observed spin switch and the predicted spin-filtering effect via chemical adsorption indicates that Mn-salophen holds potential applications in molecular spintronic devices.

Topics: Adsorption; Carbon Monoxide; Computer Simulation; Coordination Complexes; Electric Conductivity; Electrons; Fluorine; Ligands; Magnetics; Manganese; Models, Chemical; Molecular Structure; Physical Phenomena; Salicylates; Structure-Activity Relationship

A number of salophen ligands and their Zn, Ni, and Pd complexes were synthesized by an efficient one-pot mechanosynthesis protocol. The reaction products were characterized by means of complementary solid-state techniques, i.e., powder X-ray diffraction, single-crystal X-ray diffraction, and solid-state NMR spectroscopy. Four new crystal structures of metal salophen complexes as DMSO solvates are here reported. The described simple and relatively fast (about 1 h for all derivatives) procedure is a good alternative to classical methods performed in organic solvents.

Topics: Chemical Phenomena; Coordination Complexes; Ligands; Mechanical Phenomena; Models, Molecular; Molecular Structure; Nickel; Palladium; Salicylates; Spectrum Analysis; Zinc

We report on the development of optochemical sensor based on Mn(III)-salophen ionophore. The sensor was prepared by embedding the ionophore in a plasticized poly (vinyl chloride) impregnated with the chromoionophore ETH7075. Optical response to thiocyanate occurred due to thiocyanate extraction into the polymer via formation of strong complex with the ionophore and simultaneous protonation of the indicator dye yielding the optical response at 545nm. The developed optochemical sensor exhibited high selectivity for thiocyanate over other anions including the most lipophilic species such as salicylate and perchlorate. For instance, the optical selectivity coefficients, logK

Topics: Hydrogen-Ion Concentration; Ionophores; Manganese; Polyvinyl Chloride; Salicylates; Thiocyanates

Four novel dimeric bis-μ-imido bridged metal-metal bonded oxidomolybdenum(V) complexes [Mo

Topics: Animals; Antineoplastic Agents; Cattle; Cell Death; Cell Line, Tumor; Cell Proliferation; Cell Survival; Coordination Complexes; Crystallography, X-Ray; DNA; Drug Screening Assays, Antitumor; Humans; Ligands; MCF-7 Cells; Models, Molecular; Molecular Structure; Molybdenum; Oxides; Salicylates

The synthesis and characterization of three dioxo U(VI) complexes, [UO

Topics: Antineoplastic Agents; Binding Sites; Cell Proliferation; Cell Survival; DNA, Neoplasm; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Humans; Models, Molecular; Molecular Structure; Organometallic Compounds; Salicylates; Serum Albumin, Bovine; Structure-Activity Relationship; Thermodynamics; Tumor Cells, Cultured; Uranium

The development of efficient and cost effective nonenzymatic biosensors with remarkable sensitivity, selectivity and stability for the detection of biomolecules, especially glucose is one of the major challenges in materials- and electrochemistry. Herein, we report the design and preparation of nonenzymatic biosensor based on an ionic liquid tagged cobalt-salophen metal complex (Co-salophen-IL) immobilized on electrochemically reduced graphene oxide (ERGO) for the detection of glucose via an electrochemical oxidation. The bioinspired Co-salophen-IL complex has been synthesized and immobilized on ERGO, which was previously deposited on a screen printed carbon electrode (SPE) to form the Co-salophen-IL/ERGO/SPE nonenzymatic biosensor. The electrochemical behaviour of this modified electrode was studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Notably, the Co-salophen-IL/ERGO/SPE biosensor exhibited excellent electrocatalytic activity towards glucose oxidation in 0.1M NaOH, based on which an amperometric sensor has been developed. The modified electrode has shown prominent performance towards glucose detection over a wide linear range from 0.2µM to 1.8mM with a detection limit and sensitivity of 0.79µM and 62µAmM

Topics: Catalysis; Cobalt; Electrochemical Techniques; Glucose; Graphite; Ionic Liquids; Limit of Detection; Oxidation-Reduction; Oxides; Reproducibility of Results; Salicylates

Four nickel(II)-salophen complexes containing alkyl-imidazolium chains connected at the ortho or meta positions were prepared: N,N'-bis(2-hydroxy-4-methyl-3H-imidazol-1-iumbenzylideneamino)phenylenediamine (1), N,N'-bis(2-hydroxy-3-methyl-3H-imidazol-1-iumbenzylideneamino)phenylenediamine (2), N,N'-bis(2-hydroxy-3-methyl-3H-imidazol-1-iumbenzylideneamino)methyl-3H-imidazol-1-iumphenylenediamine (3), and N,N'-bis(2-hydroxy-4-methyl-3H-imidazol-1-iumbenzylideneamino)methyl-3H-imidazol-1-iumphenylenediamine (4). They protect G-quadruplex DNA (G4 -DNA) against thermal denaturation and show KA values in the range of 7.4×10(5) to 4×10(7)  m(-1) for G4 -DNA models. Complex 4 exhibits an IC50 value of 70 nm for telomerase inhibition.

Topics: Coordination Complexes; Enzyme Inhibitors; Fluorescence Resonance Energy Transfer; G-Quadruplexes; HeLa Cells; Humans; Kinetics; Nickel; Protein Biosynthesis; Salicylates; Telomerase; Vascular Endothelial Growth Factor A

A series of iron(II/III) salophen (salph) complexes involving monodentate azole-derived ligands, having the composition [Fe(II)(salph)(HL1)] (1) and [Fe(III)(salph)(L)] (2-6), where HL1=imidazole, L=1,2,4-triazol-1-ido (L2), benzo[d][1,2,3]triazol-1-ido (L3), 5-aminotetrazol-1-ido (L4), 5-phenyltetrazol-1-ido (L5), and 5-methyltetrazol-1-ido (L6) ligand, was prepared and characterized by elemental analyses, infrared, Mössbauer and X-ray photolelectron spectroscopy, magnetic data and electrospray-ionization mass spectrometry. X-ray structure of 1 revealed a distorted square-pyramidal geometry in the vicinity of the iron(II) atom. The complexes were evaluated for their in vitro antitumor activity against the panel of six human cancer cell lines (HOS, MCF7, A549, HeLa, A2780 and G-361) and were found to be highly cytotoxic, showing the best IC50 value of 58nM for [Fe(III)(salph)(L6)] (6) against the ovarian carcinoma A2780 cell line, being 200-times more effective than cisplatin. In vitro cytotoxicity of complexes 1-6 on primary culture of human hepatocytes and calf-thymus DNA (CT-DNA) binding studies using the fluorescence titration were also performed.

Topics: Antineoplastic Agents; Azoles; Drug Screening Assays, Antitumor; Female; HeLa Cells; Hepatocytes; Humans; Iron; Male; MCF-7 Cells; Neoplasms; Salicylates

Fluorine-substituted iron(III) salophene complexes (salophene = N,N'-bis(salicylidene)-1,2-phenylenediamine) were synthesized and evaluated for biological activity. All complexes showed growth inhibitory effects with IC50 values ranging from 0.05 to 2.45 μM against HT-29 colon carcinoma as well as MCF-7 and MDA-MB-231 mammary carcinoma cells (cisplatin: 5.75, 12.72, 5.81 μM, respectively). HR-CS MAS investigations revealed that the complexes were highly protein-bound already after an incubation period of 10 min and accumulated more effectively in tumor cells than cisplatin. Interestingly, the ligands were enriched in the cells too, indicating that the salophene moiety acts as a carrier ligand and mediates the uptake of the complexes. Furthermore, induction of apoptosis proved to be dependent on the substitution pattern as well as on the tumor cell line, as evidenced from the annexin V-FITC/PI assay. Most of the complexes, especially the highly active 5-Fe, showed tumor cell specific effects and no/less influence on the proliferation of T-cells generated from the peripheral blood of healthy individuals.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; DNA; Ferric Compounds; Fluorine; Humans; Salicylates; Structure-Activity Relationship

The use of micelles to transpose lipophilic receptors, such as uranyl-salophen complexes, into an aqueous environment is a valuable and versatile tool. Receptor 1 incorporated into CTABr micelles forms a supramolecular system that exhibits excellent binding properties towards fluoride in water, despite the competition of the aqueous medium. To fully evaluate the potential of micellar nanodevices, we extended our previous study to other types of surfactants and to a uranyl-salophen receptor with a more extended aromatic surface. Paramagnetic relaxation enhancement experiments were used to obtain information on the location of the two receptors within the micelles and complementary information was obtained from dynamic light scattering experiments. With these data it is possible to account for the key factors necessary to obtain an efficient supramolecular device for anion binding in water.

Topics: Binding Sites; Fluorides; Micelles; Molecular Structure; Nanotechnology; Salicylates; Water

Through the self-assembly of the (OH)2-Salophen H4L (H4L=N,N'-bis(3-hydroxylsalicylidene)benzene-1,2-diamine) with LnCl3·6H2O or Ln(NO3)3·6H2O (Ln=La, Yb or Gd) in different solvent systems MeCN-EtOH and MeCN-DMF, the mixed (L)(4-) and (H2L)(2-) coordination modes induce the formation of anion-independent while pseudo-polymorphic homoleptic linear tetranuclear complexes [Ln4(H2L)2(L)2(EtOH)2] (Ln=La, 1; Ln=Yb, 2 or Ln=Gd, 3) and [Ln4(H2L)2(L)2(DMF)2] (Ln=La, 4; Ln=Yb, 5 or Ln=Gd, 6), respectively. The result of their photophysical properties shows the characteristic NIR luminescence for both Yb(3+)-based complexes 2 and 5 with emissive lifetimes in microsecond ranges, while the difference of nearby and/or distant oscillator-based (OH and/or CH) vibrations from two coordinated EtOH or DMF molecules within the inner coordination spheres of Yb(3+) ions in the two complexes has a decisive effect on their NIR luminescent properties.

Topics: Coordination Complexes; Diamines; Luminescence; Luminescent Agents; Luminescent Measurements; Models, Molecular; Salicylates; Spectroscopy, Near-Infrared; Ytterbium

Vanadyl N,N'-bis(salicylidene)-o-phenylenediamine (salophen) complexes have been extensively investigated by cyclic voltammetry, UV-visible spectroscopy and theoretical calculations in MeCN, THF (tetrahydrofuran) and DMF (N,N-dimethylformamide), in order to elucidate the overall factors that influence the electronic density of the metal and therefore the properties of these complexes in various applications. Different substituents were introduced into the salophen skeleton to change the vanadium electron density. Results obtained and here presented showed that the substituents influence the metal electronic character in a way that cannot be easily predicted by considering only the electronic effect. Similarly, the solvent polarity or coordination ability affects the metal complex properties in an unpredictable way. Therefore, experimental and theoretical data here collected are a powerful tool to a priori design salophen ligands to obtain vanadyl complexes having the specific electronic properties suitable for desired applications.

Topics: Coordination Complexes; Electrons; Salicylates; Vanadium

Leishmaniasis is a group of disease caused by different species of the parasite Leishmania affecting millions of people worldwide. Conventional therapy relies on multiple parenteral injections with pentavalent antimonials which exhibit high toxicity and various side effects have been reported. Hence, the research for an effective and low toxic effect drug is necessary. In the present work, the synthesis, spectroscopic and analytical characterizations of stilbene derivative (H2Salophen) and its vanadium complex (VOSalophen) are reported. Besides the chemical ancillary information, investigation of the leishmanicidal effects of these compounds were provided. The biological assays against promastigote and amastigote forms of L. amazonensis have been shown that VOSalophen exhibited a strong antiparasitic activity (IC50 of 6.65 and 3.51 μM, respectively). Furthermore, the leishmanicidal activity was concentration and time-dependent. Regarding toxicity and selectivity on mammalian cells, VOSalophen have not caused significant damage to human erythrocytes in all concentrations tested and VOSalophen was almost seven times more destructive for the intracellular parasite than for macrophages. Furthermore, the leishmanicidal activity of VOSalophen in promastigote forms of L. amazonensis could be associated to mitochondrial dysfunction and increase of the reactive oxygen species (ROS) production. In L. amazonensis-infected macrophages, VOSalophen induces ROS production and a microbicidal action NO-dependent. Our biological results indicate the effective and selective action of VOSalophen against L. amazonensis and the leishmanicidal effect can be associated to parasite disorders and immumodulatory effects.

Topics: Animals; Antiprotozoal Agents; Erythrocytes; Humans; Leishmania; Leishmaniasis; Macrophages; Mitochondria; Reactive Oxygen Species; Salicylates; Vanadium Compounds

Two square-planar copper(II) complexes of 1,2-bis(2-hydroxy-3,5-di-tert-butylbenzimino)-4,5-bis(dimethylamino)benzene (1) and N-[4,5-bis(dimethylamino)-2-(oxalylamino)benzene]oxamate (2(2-)) were prepared. The crystal structures of the proligands H2L(1) and Et2H2L(2), as well as the corresponding complexes, are reported. The proligands each display a one-electron-oxidation wave, which is assigned to oxidation of the bis(dimethylamino)benzene moiety into a π radical. Complexes 1 and 2(2-) exhibit reversible one-electron-oxidation waves in their cyclic voltammograms (E1/2(1) = 0.14 and E1/2(2) = 0.31 V for 1 and E1/2(1) = -0.47 V vs Fc(+)/Fc for 2(2-)). The first process corresponds to oxidation of the bis(dimethylamino)benzene central ring into a π radical, while the second process for 1 is ascribed to oxidation of the π radical into an α-diiminoquinone. The one-electron-oxidized species 1(+) and 2(-) exhibit intense visible-near-IR absorptions, which are diagnostic of π radicals. They display a triplet signal in their electron paramagnetic resonance spectra, which stem from magnetic coupling between the ligand-radical spin and the copper(II) spin. The zero-field-splitting parameters are larger for 2(-) than 1(+) because of greater delocalization of the spin density onto the coordinated amidato N atoms. Density functional theory calculations support a π-radical nature of the one-electron-oxidized complexes, as well as S = 1 ground spin states. The electrogenerated 1(2+) comprises a closed-shell diiminoquinone ligand coordinated to a copper(II) metal center. Both 1 and 2 catalyze the aerobic oxidation of benzyl alcohol, albeit with different yields.

Topics: Benzyl Alcohol; Coordination Complexes; Copper; Electrochemistry; Electron Spin Resonance Spectroscopy; Molecular Structure; Oxamic Acid; Oxidation-Reduction; Salicylates

One-electron oxidized salophen-type complexes, [Cu(salophen)](+) (H2salophen = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminobenzene), and its methoxy derivatives, [Cu(MeO-salophen)](+) and [Cu(salophen-(MeO)2)](+) (H2MeO-salophen = N,N'-bis(3-tert-butyl-5-methoxysalicylidene)-1,2-diaminobenzene, H2salophen-(MeO)2 = N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-diamino-4,5-dimethoxybenzene), have been synthesized and structurally characterized, and their reactivities have been investigated. The solid state structures of the one-electron oxidized forms of these complexes suggested that [Cu(salophen)](+) and [Cu(MeO-salophen)](+) can be assigned to relatively localized Cu(ii)-phenoxyl radical complexes, while [Cu(salophen-(MeO)2)](+) is the diiminobenzene radical complex. On the other hand, [Cu(salophen)](+) in solution showed a different electronic structure from that of the solid sample, the radical electron being delocalized over the whole π-conjugated ligand. The reaction of these oxidized complexes with benzyl alcohol has been investigated in the presence of a large excess of substrate, which revealed the difference in the kinetic behavior between the complexes. The mechanisms of the oxidation have been discussed on the basis of the electronic and geometrical structures and the reaction kinetics.

Topics: Benzyl Alcohol; Coordination Complexes; Copper; Electrons; Models, Molecular; Salicylates

The chelating reaction of bis-salophen with uranyl to form binuclear complex uranyl-bis-salophen (UBS) was studied by fluorescence spectroscopy. The coordination reaction of UBS with fructose 1,6-bisphosphate (F-1,6-BP) to form supramolecular polymer was then studied by resonance light scattering (RLS) spectroscopy. The reaction of bis-salophen with uranyl results in a remarkable enhancement of fluorescence intensity. The maximum emission wavelength of the fluorescence is at 471nm. The reaction of UBS with F-1,6-BP results in a remarkable enhancement of RLS intensity. The maximum scattering wavelength of the RLS is at 460nm. The two reactions were used to establish fluorescence method for the determination of uranium (VI) and RLS method for the determination of F-1,6-BP, respectively. Under optimum conditions, the linear ranges for the detection of uranium (VI) and F-1,6-BP are 0.003-0.35nmol/mL and 0.05-5.0nmol/mL, respectively. The detection limits are 0.0017nmol/mL and 0.020nmol/mL, respectively. The proposed fluorescence method has been successfully applied for the determination of uranium (VI) in environmental water samples with the recoveries of 97.0-104.0%. The proposed RLS method has also been successfully applied for the determination of F-1,6-BP in medicine injection samples with the recoveries of 98.5-102.3%.

Topics: Chelating Agents; Fluorescence; Fresh Water; Fructosediphosphates; Limit of Detection; Organometallic Compounds; Pharmaceutical Preparations; Salicylates; Spectrometry, Fluorescence; Uranium

A sensitive and selective copper(II) fluorescence Schiff base chemical sensor receptor 1 (short for N,N'-bis(salicylidene)-o-phenylenediamine) has been prepared. The fluorescence of receptor 1 in pH 8.2 phosphate buffer solution can be dramatically quenched by Cu(2+), whereas it is nearly unaffected by other metal ions. Based on this, a sensitive and selective fluorescent quenching method for Cu(2+) detection has been established. Under the optimum conditions, a good linear relation exists between the quenching efficiency (F0/F) and the concentration of Cu(2+) in the range of 1.0 × 10(-7)-2.5 × 10(-6) mol L(-1). The detection limit (3σ) for Cu(2+) determination is 2.0 × 10(-8) mol L(-1). The present method has been successfully used for quantification of Cu(2+) in soybean milk powder. Furthermore, the fluorescence switch property of the system was explored, and the system might be applied for determination of glutathione and construction of molecular logic gate.

Topics: Calibration; Copper; Fluorescent Dyes; Hydrogen-Ion Concentration; Limit of Detection; Salicylates; Spectrum Analysis

As a neutral carrier component for the preparation of a potentiometric membrane sensor, the affinity and selectivity of the salophen type Schiff base ligand obtained by 1:2 condensation of 2.3-diaminopyridine with salicylaldehyde toward a series of common cations has been fully examined by DFT/B3LYP and integral equation formalism polarizable continum model (IEF-PCM or only given with PCM as default input in the computations) in combination with the experimental data. Both the potentiometric measurements and DFT calculations have exhibited that the ionophore shows appreciable selectivity for Cu(2+) ion over other cations. Four different approaches where the last three are the modified version of each other have been evaluated and compared with potentiometric data. Based upon the results of comparison among the approaches suggested to verify the selective behavior of ionophore toward Cu(2+), PCM implemented approach having a whole computational groundwork has given well-matched results with the observed data and with the method augmented with experimental hydration energies. The foremost interferences were detected by determining potentiometric selectivity coefficients for each metal ion relative to Cu(2+) and compared to the results obtained by the DFT calculations.

Topics: Aldehydes; Aminopyridines; Computer Simulation; Copper; Ionophores; Models, Chemical; Models, Molecular; Molecular Structure; Potentiometry; Salicylates; Schiff Bases; Structure-Activity Relationship

A series of methoxy- and fluorine-substituted [salophene]platinum(II) complexes (salophene=N,N'-bis(salicylidene)-1,2-phenylenediamine) were synthesized and characterized by (1) H NMR spectroscopy and mass spectrometry. The structure was confirmed on the example of [5-OCH3 -salophene]platinum(II) (4-Pt) by crystal structure analysis. The cytotoxicity of all complexes against MCF-7 cells showed strong dependence on the kind of substituent and its position on the salicylidene moiety, whereas 1-Pt (H), 3-Pt (4-OCH3 ), and 6-Pt (3-F) exhibited high antiproliferative effects (IC50 <2 μM). Drug lipophilicity and cellular accumulation were analyzed in an attempt to explain the differences in antitumor potency. To gain insight into their mode of action, DNA interaction studies were performed, in which compounds such as 1-Pt acted as non-DNA-binding platinum anticancer drugs, as neither intercalation nor DNA covalent binding were detected.

Topics: Antineoplastic Agents; Cell Proliferation; Cell Survival; Circular Dichroism; Coordination Complexes; Crystallography, X-Ray; DNA; Humans; Magnetic Resonance Spectroscopy; MCF-7 Cells; Molecular Conformation; Platinum; Salicylates; Viscosity

The cyclic voltammetric behavior of [FeIIICl(salen)] complexes has been investigated in CH3CN and compared to that obtained with [CoII(salen)] analogues. Details of the mechanism associated with iron- and cobalt-salen complex reduction in the presence of the lithium cation have been elucidated by comparison of simulated and experimental voltammograms. Electrogenerated [FeICl(salen)]²⁻ and [FeICl(salophen)]²⁻ complexes catalyze the dehalogenation of halo-alkyl compounds as is the case with [CoI(salen)]⁻ complexes, even in the presence of the lithium cation which allows the reduction to occur at a less negative potential.

Topics: Catalysis; Coordination Complexes; Electrochemical Techniques; Ethylenediamines; Ferrous Compounds; Kinetics; Lithium; Oxidation-Reduction; Salicylates

The synthesis, characterization, and luminescent properties of a series of 5,5'-X-substituted salophen ligands, X = OCH3, Br, and NO2, and the corresponding Zn(II) complexes are reported here. Their biological activity has been analyzed and related to the different Lewis acid character of the complexes. In vitro studies (AFM and absorption and emission titrations) show that the strongest interaction with free plasmid DNA is observed for 5,5'-dinitro-substituted Zinc-salophen complex 3b. Semiempirical theoretical calculations together with redox potential measurements suggest that this might be interpreted as a direct consequence of this compound having the hardest Lewis acid character. Cellular uptake and cytotoxicity studies undertaken with these metal complexes show that they enter the cells but are not cytotoxic.

Topics: 3T3 Cells; Animals; DNA; Lewis Acids; Mice; Mice, Inbred BALB C; Models, Molecular; Molecular Structure; Organometallic Compounds; Plasmids; Salicylates; Zinc

A salophen cobalt(II) complex enables water oxidation at neutral pH in photoactivated sacrificial cycles under visible light, thus confirming the high appeal of earth abundant single site catalysis for artificial photosynthesis.

Topics: Catalysis; Cobalt; Coordination Complexes; Light; Models, Biological; Molecular Structure; Oxidation-Reduction; Salicylates; Water

A Zn-salophen complex has been incorporated into POPC large unilamellar liposomes (LUV) obtained in phosphate buffer at pH 7.4. Fluorescence optical microscopy and anisotropy measurements show that the complex is located at the liposomal surface, close to the polar headgroups. The interaction of the POPC phosphate group with Zn(2+) slowly leads to demetallation of the complex. The process follows first order kinetics and rate constants have been measured fluorimetrically in pure water and in buffered aqueous solution. The coordination of the phosphate group of monomeric POPC with salophen zinc also occurs in chloroform as detected by ESI-MS measurements. The effect of the Zn-salophen complex on the stability of POPC LUV has been evaluated at 25°C by measuring the rate of release of entrapped 5(6)-carboxyfluorescein (CF) in the presence and in the absence of Triton X-100 as the perturbing agent. It turns out that the inclusion of the complex significantly increases the stability of POPC LUV.

Topics: Kinetics; Octoxynol; Phosphatidylcholines; Salicylates; Unilamellar Liposomes; Zinc

Topics: Benzene; Copper; Crystallography, X-Ray; Electrons; Free Radicals; Imines; Molecular Structure; Organometallic Compounds; Oxidation-Reduction; Quantum Theory; Salicylates

A novel organic nanowire-Ag nanoparticle hybrid was facilely fabricated and demonstrated to be highly sensitive and selective for dopamine fluorescence-enhancement detection.

Topics: Dopamine; Fluorescence; Metal Nanoparticles; Nanowires; Salicylates; Silver; Zinc

A double-receptor sandwich supramolecule method for the separation and determination of trace uranium was proposed in this paper. One receptor is a salophen which can react with uranyl to form a uranyl-salophen complex, and another receptor is an oligonucleotide which can bind uranyl to form oligonucleotide-uranyl-salophen supramolecule. The salophen was immobilized on the surface of silica gel particles and used as the solid phase receptor for separating uranium from solution. The oligonucleotide was labeled with a fluorescent group and used as the labeled receptor for quantitatively analyzing uranium. In the procedure of separation and determination, uranyl ion was first combined with the solid phase receptor and then conjugated with the labeled receptor to form the sandwich-type supramolecule. The labeled receptor in the sandwich supramolecule was then eluted and determined by fluorescence analysis. The experimental results demonstrate that this method has a number of advantages such as high selectivity, excellent pre-concentration capability, high sensitivity, good stability and low cost. Under optimal conditions, the linear range for the detection of uranium is 0.5-30.0 ng mL(-1) with a detection limit of 0.2 ng mL(-1). The proposed method was successfully applied for the separation and determination of uranium in real samples with the recoveries of 95.0-105.5%.

Topics: Fluoresceins; Fluorescent Dyes; Limit of Detection; Oligonucleotides; Organometallic Compounds; Salicylates; Sensitivity and Specificity; Silica Gel; Uranium

The Schiff base N,N'-bis(salicylidene)-o-phenylenediamine (salophen) was prepared by the condensation of salicylaldehyde with o-phenylenediamine in ethanol solution. The compound was characterized by elemental analysis, infrared (IR), (1)H, (13)C and (1)H(15)N HMBC nuclear magnetic resonance (NMR) spectroscopic measurements, and also by X-ray diffraction. The tautomerism of salophen was also studied by calculations using density functional theory (DFT). Two of the three tautomers were shown to coexist. A comparison of the DFT data of the three tautomers has shown that the most stable one is salophen 1, which is in accordance with experimental X-ray crystallographic data.

Topics: Aldehydes; Crystallography, X-Ray; Isomerism; Magnetic Resonance Spectroscopy; Models, Molecular; Quantum Theory; Salicylates; Schiff Bases; Spectroscopy, Fourier Transform Infrared

Substitution on the aromatic bridge of a nickel(II) salophen complex with electron-donating dimethylamino substituents creates a ligand with three stable, easily and reversibly accessible oxidation states. The one-electron-oxidized product is characterized as a nickel(II) radical complex with the radical bore by the central substituted aromatic ring, in contrast to other nickel(II) salen or salophen complexes that oxidize on the phenolate moieties. The doubly oxidized product, a singlet species, is best described as having an iminobenzoquinone bridge with a vinylogous distribution of bond lengths between the dimethylamino substituents. Protonation of the dimethylamino substituents inhibits these redox processes on the time scale of cyclovoltammetry, but electrolysis and chemical oxidation are consistent with deprotonation occurring concomitantly with electron transfer to yield the mono- and dioxidized species described above.

Topics: Crystallography, X-Ray; Models, Molecular; Molecular Structure; Nickel; Organometallic Compounds; Oxidation-Reduction; Protons; Quantum Theory; Salicylates

We demonstrate the cytotoxic potential of the Schiff base iron complex [Fe(III)(salophene)Cl] in vitro and ex vivo and illustrate its ability to overcome multiple drug resistance in vincristine and daunorubicine resistant leukemic cells (Nalm-6). Treatment of lymphoma cells (BJAB) with [Fe(III)(salophene)Cl] led to the exclusion of unspecific necrosis, a concentration-dependent inhibition of proliferation and a specific apoptotic cell death. We further detected a significant loss of the mitochondrial membrane potential in lymphoma cells and an up- and downregulation of various apoptosis relevant genes, respectively, indicating the involvement of the intrinsic mitochondrial pathway.

Topics: Apoptosis; Biomarkers, Tumor; Blotting, Western; Cell Line, Tumor; Cell Proliferation; Daunorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Ferric Compounds; Humans; Leukemia; Lymphoma; Membrane Potential, Mitochondrial; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Salicylates; Vincristine

The approach of non-covalent conjugation has recently been used and a number of metal complexes have been encaged in a protein scaffold to form functional metallo proteins. Here we investigate a novel artificial superoxide dismutase enzyme based on the non-covalent conjugation of bovine serum albumin and the manganese(III) complex of N,N'-bis(salicylidene)-3,4-diaminobenzoic acid. We report the intriguing ability of the albumin environment to increase the SOD activity of the inorganic complex. We also determined the binding constant with BSA by CD spectroscopy.

Topics: Animals; Biomimetic Materials; Cattle; Manganese; Models, Molecular; Organometallic Compounds; Salicylates; Serum Albumin, Bovine; Spectrum Analysis; Superoxide Dismutase

Oxidative stress is the hallmark of several pathologies like arthritis, hypertension and many neurodegenerative disorders such as Parkinson's and Alzheimer's diseases. In this scenario, antioxidant compounds can play a pivotal role in treating these severe pathologies. The synthesis of molecules able to mimic physiologically-relevant proteins is nowadays of particular interest. Several transition metal complexes, especially manganese(III) complexes with porphyrin and salen-type ligands, have been reported to be superoxide scavengers. Here we report the synthesis and spectroscopic characterization of manganese(III) complexes of 5[4-(6-O-β-cyclodextrin)-phenyl],10,15,20-tri(4-hydroxyphenyl)-porphyrin and of 6(A)-deoxy-6(A)[(S-cysteamidobenzoyl(3,4-diamino)-N,N'-bis(salicylidene))]-β-cyclodextrin. The superoxide dismutase activity of the metal complexes was investigated by indirect methods. The catalase and peroxidase activities were tested using ABTS assays.

Topics: Antioxidants; beta-Cyclodextrins; Catalase; Coordination Complexes; Manganese; Peroxidases; Porphyrins; Salicylates; Superoxide Dismutase

Schiff base transition metal complexes are an important class of compounds with great potential for therapeutic interventions. However, data on antileukemic and antilymphoma effects of these complexes are limited. The activity of N,N'-bis(salicylidene)-1,2-phenylenediamine (salophene, 1), its iron(II/III) and manganese(II/III) complexes as well as rac-trans-N,N'-bis(salicylidene)-1,2-cyclohexanediamine (saldach, 2) and its respective iron(II/III) complexes was evaluated against U-937 non-Hodgkin's lymphoma and the HL-60, SUP-B15, and K-562 leukemia cell lines. The free ligands induced in all cell lines, if at all, only marginal, concentration-dependent growth inhibitory effects, and did not trigger Cu/Zn superoxide dismutase (Cu/Zn SOD) release or induce apoptosis. [Fe(II) (salophene)] (3) and [Fe(III) (salophene)Cl] (4) blocked cellular growth, caused a strong release of Cu/Zn SOD and induced apoptosis. In contrast, the manganese analogs [Mn(II) (salophene)] (5) and [Mn(III) (salophene)OAc] (6) inhibited cell growth, caused the programmed cell death only at higher concentrations and did not provoke release of Cu/Zn SOD in any of the four cell lines. Weaker cell death-promoting effects were observed when the salophene moiety of 3 and 4 was replaced with saldach (complexes 7 and 8), indicating the influence exerted by the ligand structure. In conclusion, Schiff base transition metal complexes induce strong inhibitory effects on human lymphoma and leukemia cells.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Cyclohexylamines; Dose-Response Relationship, Drug; Humans; Iron; Leukemia; Ligands; Lymphoma; Manganese; Molecular Structure; Organometallic Compounds; Salicylates; Schiff Bases; Superoxide Dismutase

Dinuclear Cu(II) complexes, [Cu(2) (salophen)(2) ] (1) and [Cu(2) (salen)(2) ] (2), with Schiff bases derived from salicylaldehyde and o-phenylenediamine (ophen) or ethylenediamine (en) were synthesized and characterized. They exhibit square-planar geometry with CuN(2) O(2) coordination, where the dianionic Schiff base acts as a tetradentate N(2) O(2) donor ligand. Calf thymus (CT)-DNA Binding studies revealed that the complexes possess good binding propensities (K(b) =3.13×10(5) for 1 and K(b) =2.99×10(5)  M(-1) for 2). They show good DNA-cleavage abilities under oxidative and hydrolytic conditions. Complex 1 binds and cleaves DNA more efficiently as compared to 2 due to the presence of an extended aromatic phenyl ring which might be involved in an additional stacking interaction with DNA bases. From the kinetic experiments, hydrolytic DNA-cleavage rate constants were determined as 1.54 for 1 and 0.72 h(-1) for 2. The nuclease activities of 1 and 2 are significant, giving rise to (2.03-2.88)×10(7) -fold rate enhancement compared to non-catalyzed DNA cleavage.

Topics: Animals; Antineoplastic Agents; Binding Sites; Cattle; Copper; DNA; DNA Cleavage; Ethylenediamines; Models, Molecular; Neoplasms; Organometallic Compounds; Salicylates; Schiff Bases

Al(III)- and Zr(IV)-salophens of novel structures were tested as anion-selective ionophores. It was shown that these compounds are highly selective to fluoride and give selectivity greatly deviating from classical Hofmeister pattern, when doped into the polymeric membrane of ion-selective electrode (ISE). The following selectivity sequence has been recorded for both ionophores: F(-) > ClO(4)(-) > SCN(-) > NO(3)(-) approximately Br(-) approximately Cl(-). The results of potentiometric and spectrophotometric measurements allow to conclude that the nature and structure of salophen ligands influence stability of ISE working parameters. An increase in salophen ligands lipophilicity results in prolongation of the ISE lifetime, most likely due to slower ionophore decomposition caused by the hydrolysis of imine bonds in salophen structure. Ion-selective electrodes (ISEs) with the most successful Al(III)-salophen exhibited a stable, fast and near-Nernstian fluoride response and a functional lifetime near 3 weeks and selectivity coefficients with log K(F(-), Y(-))(pot) as follows: -2.8 (Y(-)=Br(-)), -2.7 (Cl(-)), -2.8 (NO(3)(-)), -1.5 (SCN(-)), -1.3 (ClO(4)(-)), which is better than for other ones based on Zr(IV)- and Al(III)-salophens and salens described to date.

Topics: Aluminum; Cations; Ethylenediamines; Fluorides; Ion-Selective Electrodes; Ionophores; Polymers; Potentiometry; Salicylates; Zirconium

We synthesized methoxy-substituted iron(III)-salophene complexes ([Fe(III)(OMe-salophene)Cl] with salophene = N,N'-bis(salicylidene)-1,2-phenylenediamine) and analyzed their biological activity in MCF-7 and MDA-MB-231 breast cancer as well as in HT-29 colon carcinoma cells. The results obtained in a time-dependent chemosensitivity test clearly demonstrated the correlation between the cytotoxicity of the complexes and the position of methoxy substituents in the salicylidene moieties: 3-OCH(3) (4) < 5-OCH(3) (8) < H (2) < 4-OCH(3) (6) = 6-OCH(3) (10). Compounds 6 and 10 caused cytocidal effects already at a concentration of 0.5 μM. Both lead compound 2 and complex 8 showed similar time response curves, however, with a 5-fold lower activity compared to 6 and 10, respectively. Referring to [Fe(III)(salophene)Cl] (2), methoxy substitution was accompanied with the loss of tumor cell selectivity. Moreover, the free ligands (1, 3, 5, 7, and 9) were inactive.

Topics: Cell Line, Tumor; Cell Proliferation; Ferric Compounds; Humans; Magnetic Resonance Spectroscopy; Salicylates

A new water soluble zinc-salophen complex with appended D-glucose moieties was synthesized and characterized. Its binding properties toward six aminoacids were investigated by UV-vis spectrophotometric titrations. Association constants showed to be unfavorably affected by increasing steric hindrance of the side chain. Quite surprisingly, different association constants were measured for the L and D enantiomers. These data suggest that aminoacids are bound via two interactions, zinc-carboxylate coordination and two hydrogen bonds between the ammonium group of the aminoacid and two oxygen atoms of one D-glucose moiety. Such conclusion is supported by the result of semiempirical (PM3) calculations. Notably, the K(L)/K(D) value of 9.6 observed for the association of phenylalanine rivals with the highest values found for the chiral recognition of aminoacids in water.

Topics: Absorption; Amino Acids; Glucose; Hydrogen-Ion Concentration; Models, Molecular; Molecular Conformation; Organometallic Compounds; Salicylates; Solubility; Stereoisomerism; Substrate Specificity; Temperature; Titrimetry; Water; Zinc

We developed N,N'-bis(salicylidene)-1,2-phenylenediamine (salophene, 1) as a chelating agent for metal ions such as Mn(II/III), Fe(II/III), Co(II), Ni(II), Cu(II), and Zn(II). The resulting complexes, from which owing to the carrier ligand a selective mode of action is assumed, were tested for antiproliferative effects on the MCF-7 breast cancer cell line. The cytotoxicity in this assay depended on the nature of the transition metal used. Iron complexes in oxidation states +II and +III (3, 4) strongly reduced cell proliferation in a concentration-dependent manner, whereas, e.g., the manganese analogues 5 and 6 were only marginally active. Therefore, the [N,N'-bis(salicylidene)-1,2-phenylenediamine]iron(II/III) complexes 3 and 4 were selected for studies on the mode of action. Both complexes possessed high activity against various tumor cells, for instance, MDA-MB-231 mammary carcinoma cells as well as HT-29 colon carcinoma cells. They were able to generate reactive oxygen species, showed DNA binding, and induced apoptosis. Exchange of 1 by N,N'-bis(salicylidene)-1,2-cyclohexanediamine (saldach, 2) yielding complexes 7 and 8 reduced the in vitro effects drastically. An unequivocal mode of action cannot be deduced from these results, but it seems to be very likely that cell death is caused by interference with more than one intracellular target.

Topics: Adenocarcinoma; Animals; Apoptosis; Breast Neoplasms; Carcinoma; Cattle; Cell Line, Tumor; Chelating Agents; Circular Dichroism; Colonic Neoplasms; DNA; Electric Impedance; Female; Humans; Metals; Oxidation-Reduction; Oxygen Consumption; Reactive Oxygen Species; Salicylates; Thymus Gland

Several porphyrin and salophen complexes with Rh(III) are examined as ionophores to prepare nitrite selective polymeric membrane electrodes. All ionophores tested exhibit preferred selectivity toward nitrite anion. Enhanced potentiometric nitrite selectivity is observed in the presence of either lipophilic anionic as well as cationic sites within the membranes, suggesting that the ionophores can function via either a charged or a neutral carrier response mechanism. Among a range of complexes and membrane formulations examined, optimal nitrite selectivity and reversible response down to 5 x 10(-6) M is achieved using Rh(III)-tetra(t-butylphenylporphyrin) as the ionophore in the presence of lipophilic cationic sites in plasticized poly(vinyl chloride) membrane. Response times are substantially longer than typical membrane electrodes apparently because of a slow nitrite ligation reaction with Rh(III); however, a significant improvement in dynamic EMF response can be realized by optimizing the membrane formulation and increasing the temperature. The selectivity observed with these membranes is greater than the best nitrite selective electrodes reported to date in the literature based on lipophilic Co(III)-corrin complexes, allowing the new nitrite electrodes to be utilized to determine the level of nitrite in meats with good correlation to the colorimetric Griess assay method.

Topics: Electrodes; Hydrogen-Ion Concentration; Ionophores; Ligands; Meat; Membranes, Artificial; Metalloporphyrins; Nitrites; Plasticizers; Polymers; Potentiometry; Rhodium; Salicylates; Sensitivity and Specificity; Time Factors

An optical sensor is described for a sensitive and selective spectrophotometric determination of Pb(II) ions in aqueous solution. A sensor membrane based on 4-hydroxy salophen has been developed for the determination of Pb(II) ions that displays excellent performance. The membrane responds to lead(II) ions, giving a color change from colorless to yellow in a buffer solution (pH 3.1). The optode has a linear range of 1.0 x 10(-3)-1.0 x 10(-7) mol L(-1) Pb(II) ions with a detection limit of 8.6 x 10(-8) mol L(-1) Pb(II). The response time is within 10 min depending on the concentration of Pb(II) ions such that it can quantitatively detect Pb(II) even at concentration levels of 8.6 x 10(-8) mol L(-1) Pb(II) (0.018 ppm). The optode developed here is found to be stable, cost effective, easy to prepare, and efficient for direct determination of Pb(II) in a variety of aqueous samples using spectrophotometry. However, it is for one time use only as the reaction of Pb(II) with 4-hydroxy salophen is irreversible. The optode was successfully used for measuring Pb(II) ions in different water samples and in SRM sample.

Topics: Colorimetry; Electrochemical Techniques; Lead; Membranes, Artificial; Methods; Salicylates; Water Pollutants, Chemical

Open-tubular CEC (OT-CEC) with a new stationary phase, salophene-lanthanide-Zn(2+) complex, has been applied to the separation of tryptic peptides of native BSA and BSA glycated by glucose and ribose. Glycation of proteins (non-enzymatic modification by sugars) significantly affects their properties and it is of great importance from a physiological point of view. Separation of tryptic peptides of glycated BSA by CZE was poor because of their strong adsorption to the bare fused silica capillary. An improved separation of tryptic peptides of both native and glycated BSA was achieved by OT-CEC in the fused silica capillary non-covalently coated with salophene-lanthanide-Zn(2+) complex, which suppressed the adsorption of peptides to the capillary and via specific interactions with some (glyco)peptides enhanced selectivity of the separation. Significant differences have been found in OT-CEC analyses of tryptic hydrolysates of native and glycated BSA. In OT-CEC-UV profile of tryptic peptides of native BSA, 44 peaks could be resolved, whereas a reduced number of 38 peaks were observed in the profile of tryptic peptides of glucose-glycated BSA and only 30 peaks were found in the case of ribose-glycated BSA. The developed OT-CEC can be potentially used for monitoring of protein glycation.

Topics: Adsorption; Electrophoresis, Capillary; Glucose; Lanthanoid Series Elements; Peptide Fragments; Salicylates; Serum Albumin, Bovine; Trypsin; Zinc

The free ligands, 2-{(o-hydroxyaryl)azo}-1-N-salicylidene phenylamine, H(2)L [where H(2)L = RC(6)H(4)N=NC(6)H(4)N=CH-C(6)H(4)OHR = p-H for H(2)L(1), p-Me for H(2)L(2) and p-Cl for H(2)L(3)], were prepared by the condensation of salicylaldehyde with 2-{(o-hydroxy aryl)azo} aniline. Reaction of H(2)L with VOSO(4) afforded the oxovanadium complex, (L)V(O)(H(2)O). The (L(1))V(O)(H(2)O) complex displays two reversible responses at 0.7 V and -0.65 V vs. SCE in cyclic voltammetry. Catalytic activity of (L(1))V(O)(H(2)O) toward H(2)O(2) induced oxidation of organic thioethers to sulfoxide and sulfones have been examined. The cytotoxicity of (L(1))V(O)(H(2)O) has also been examined on human lung cancer cells.

Topics: Azo Compounds; Cell Cycle; Cell Death; Cell Survival; Crystallography, X-Ray; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Electrochemistry; Humans; Ligands; Models, Molecular; Molecular Structure; Organometallic Compounds; Salicylates; Structure-Activity Relationship; Tumor Cells, Cultured; Vanadium

Recognition of inorganic phosphates PO(4)(3-), P(2)O(7)(4-), and P(3)O(10)(5-) and nucleotides AMP(2-), ADP(3-), and ATP(4-) by Zn(2+)-salophen complexes 1 and 2 in ethanol was investigated by different spectroscopic techniques. (31)P NMR and mass spectrometry showed that anions of both series are bound by 1 and 2, while absorption and emission studies revealed that only nucleotides produce relevant changes in the spectral properties of the two hosts. (1)H NMR studies proved that the adenine aromatic group is involved in the complexation, thus pointing out the role of supramolecular ditopic receptors played by salophen derivatives toward this class of biologically relevant substrates. The lifetime of the photogenerated triplet state of the Zn(2+)-salophen compounds was measured by nanosecond laser flash photolysis, and the observed changes upon increasing the concentration of nucleotides allowed the identification of the formation of a 1:0.5 host/guest intermediate complex additionally to the formation of a 1:1 complex.

Topics: Adenine Nucleotides; Anions; Magnetic Resonance Spectroscopy; Models, Molecular; Salicylates; Spectrometry, Mass, Electrospray Ionization; Spectrophotometry, Ultraviolet; Zinc

Topics: Cetrimonium; Cetrimonium Compounds; Electric Conductivity; Electrochemistry; Ionic Liquids; Magnetic Resonance Spectroscopy; Micelles; Protons; Salicylates; Uranium Compounds

Topics: Binding Sites; Cetrimonium; Cetrimonium Compounds; Fluorides; Magnetic Resonance Spectroscopy; Micelles; Molecular Structure; Organometallic Compounds; Reference Standards; Salicylates; Surface-Active Agents; Uranium Compounds; Water

cis-Bis(2,2'-bipyridyl)dichlororuthenium(II)dihydrate complexed with Schiff bases salen (L1H2) and salophen (L2H2) provides complexes of compositions [Ru(L1)(bpy)2] 1 and [Ru(L2)(bpy)2] 2, respectively with cavity. The structure of these complexes characterized by spectroscopic studies were supported by their optimized geometries based on DFT calculations. Complexes 1 and 2 were then allowed to interact with methanolic solution of sodium perchlorate separately providing corresponding complexes 3 and 4 with the compositions 1.NaClO4 and 2.NaClO4, respectively. The formation constants were then evaluated by monitoring the changes in their UV-visible spectral features upon addition of different amount of sodium salts in the presence of a fixed concentration of the ruthenium complexes at a wavelength 294 nm. Emission (solution), luminescence microscopic and cyclic voltammetric studies of these complexes have also been made.

Topics: 2,2'-Dipyridyl; Chelating Agents; Chemical Phenomena; Chemistry, Physical; Dimethyl Sulfoxide; Electrochemistry; Ethylenediamines; Ligands; Methanol; Molecular Structure; Perchlorates; Ruthenium; Salicylates; Schiff Bases; Sodium; Sodium Compounds; Solutions; Spectrophotometry, Ultraviolet

Quantitative infrared (IR) and Raman spectroscopic approach for determination of phenacetin (Phen) and salophen (Salo) in binary solid mixtures with caffeine: phenacetin/caffeine (System 1) and salophen/caffeine (System 2) is presented. Absorbance ratios of 746 cm(-1) or 721 cm(-1) peaks (characteristic for each of determined compounds in the Systems 1 and 2) to 1509 cm(-1) and 1616 cm(-1) (attributed to Phen and Salo, respectively) were used. The IR spectroscopy gives confidence of 98.9% (System 1) and 98.3% (System 2), while the Raman spectroscopic data are with slightly higher confidence of 99.1% for both systems. The limits of detection for the compounds studied were 0.013 and 0.012 mole fraction for IR and Raman methods, respectively. Solid-state linear dichroic infrared (IR-LD) spectral analysis of solid mixtures was carried out with a view to obtaining experimental IR spectroscopic assignment of the characteristic IR bands of both determined compounds. The orientation technique as a nematic liquid crystal suspension was used, combined with the so-called reducing-difference procedure for polarized spectra interpretation. The possibility for obtaining supramolecular stereo structural information for Phen and Salo by comparing spectroscopic and crystallographic data has also been shown. An independent high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis was performed for comparison and validation of vibrational spectroscopy data. Applications to 10 tablets of commercial products APC and Sedalgin are given.

Topics: Analgesics; Caffeine; Chromatography, High Pressure Liquid; Phenacetin; Salicylates; Spectrophotometry, Infrared; Spectrum Analysis, Raman; Tandem Mass Spectrometry

The complexation reaction between Cu2+, Co2+ and Ni2+ metal cations with N,N'-bis(salicylidene)-1,2-phenylenediamine (salophen), in three nonaqueous polar solvents such as: acetonitrile (AN), dimethyl sulfoxide (DMSO), methanol (MeOH) and two binary mixtures of AN:DMSO and AN:MeOH at 25 degrees C were studied by spectrophotometric and conductometric methods. All investigated metal ions form 1:1 ML complex which their stability constants were determined and increase as Irving-Williams stability order of Co2+ < Ni2+ < Cu2+ in all solvent systems except in the pure MeOH and binary mixture of AN:MeOH 20:80; in which, Ni2+ < Co2+ < Cu2+ was observed. The values of the thermodynamic parameters (DeltaH degrees , DeltaS degrees and DeltaG degrees ) for complexation reactions obtained from the temperature dependence of the stability constants and the results show that for all metal ion complexes, the value of DeltaH degrees , DeltaS degrees and DeltaG degrees are solvent dependent.

Topics: Electric Conductivity; Ions; Molecular Structure; Salicylates; Solvents; Spectrophotometry; Thermodynamics; Transition Elements

An interesting series of binuclear ruthenium(III) Schiff base complexes bearing bis-salophen/bis-naphophen units of the general composition [(EPh(3))(X)Ru-L-Ru(X)(EPh(3))] (where E=P or As; X=Cl or Br; L=binucleating dianionic tetradentate ligands) have been synthesized and characterized by analytical (elemental analysis, magnetic susceptibility measurements), spectral (FT-IR, UV-vis and EPR) and electrochemical methods. These ruthenium(III) complexes have two N(2)O(2) metal binding sites, which are linked to each other with a biphenyl bridge and acts as potential catalyst for oxidation of wide range of primary and secondary alcohols to corresponding aldehydes or ketones with moderate to high conversion in the presence of N-methylmorpholine-N-oxide (NMO). The formation of high-valent Ru(V)=O species as a catalytic active intermediate is proposed for the catalytic processes.

Topics: Alcohols; Electrochemistry; Electromagnetic Phenomena; Electron Spin Resonance Spectroscopy; Magnetics; Molecular Structure; Oxidation-Reduction; Ruthenium Compounds; Salicylates; Schiff Bases; Spectrophotometry; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared

Topics: 4-Butyrolactone; Biodegradation, Environmental; Catalysis; Chromium; Hydroxybutyrates; Organometallic Compounds; Polymers; Salicylates; Stereoisomerism

Fluorescent sensors for the detection of chemical explosives are in great demand. It is shown herein that the fluorescence of ZnL* (H2L=N,N'-phenylene-bis-(3,5-di-tert-butylsalicylideneimine)) is quenched in solution by nitroaromatics and 2,3-dimethyl-2,3-dinitrobutane (DMNB), chemical signatures of explosives. The relationship between the structure and fluorescence of ZnL is explored, and crystal structures of three forms of ZnL(base), (base=ethanol, tetrahydrofuran, pyridine) are reported, with the base=ethanol structure exhibiting a four-centered hydrogen bonding array. Solution structures are monitored by 1H NMR and molecular weight determination, revealing a dimeric structure in poor donor solvents which converts to a monomeric structure in the presence of good donor solvents or added Lewis bases to form five-coordinate ZnL(base). Fluorescence wavelengths and quantum yields in solution are nearly insensitive to monomer-dimer interconversion, as well as to the identity of the Lewis base; in contrast, the emission wavelength in the solid state varies for different ZnL(base) due to pi-stacking. Nitroaromatics and DMNB are moderately efficient quenchers of ZnL*, with Stern-Volmer constants KSV=2-49 M-1 in acetonitrile solution.

Topics: Butanes; Crystallography, X-Ray; Electrochemistry; Hydrogen Bonding; Ligands; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Structure; Nitrogen Compounds; Oxidation-Reduction; Salicylates; Spectrometry, Fluorescence; Titrimetry; Zinc Compounds

The Al(III)-salophen complex 1 exhibited strong spectroscopic changes specifically upon addition of polyG and GpG, while double stranded DNA and RNA, and single stranded polyA, polyU and polyC induced negligible spectral changes of 1. Titrations with mono-nucleotides yielded no spectroscopic changes, revealing that there must be at least two consecutive guanines in single stranded oligonucleotide structure for a measurable spectroscopic change of 1. Preliminary results show that 1 has moderate antiproliferative effect on a number of human tumour cell lines.

Topics: Aluminum; Animals; Binding Sites; Cell Line, Tumor; DNA; HeLa Cells; Humans; Magnetic Resonance Spectroscopy; Poly G; Salicylates; Solubility; Spectrophotometry, Ultraviolet; Static Electricity

The nickel complexes 1(+)-3(+) exhibit a delocalized radical character, the extent of which depends on the electronic properties of the phenolate para-substituent.

Topics: Electrons; Models, Molecular; Nickel; Organometallic Compounds; Oxidation-Reduction; Salicylates

The new ion-selective electrodes (ISEs) based on salphenH2 derivatives such as N,N'-(propylenedioxy)benzenebis(salicylideneimine) L1 and N,N'-4,5-(propylenedioxy)benzenebis(3,5-di-tert-butylsalicylideneimine) L2 as cation carriers are developed for a uranyl ion. The combination of these new ionophores with tris(2-ethylhexyl)phosphate (TEHP) as a plasticizer particularly shows near Nernstian slope in the wide concentration range (1.0 x 10(-6) to 1.0 x 10(-2) M) of UO2(2+) and is observed well in the pH range from 1.0 to 5.0 with a response time less than 20s. Since the employed ionophores were confirmed to form well-defined stable 1:1 complexes with UO2(2+), the observed high selectivity for a uranyl ion over the other cations was attributed to the selective complexation as well as the lipophilic behavior of these ligands especially for L2. The proposed electrodes offered practically low detection limit of 6.5 x 10(-7) M and reasonably good end-points within experimental error were obtained when the sensor was used as an indicator electrode for the potentiometric titration.

Topics: Ion-Selective Electrodes; Ionophores; Ions; Molecular Structure; Plasticizers; Polymers; Potentiometry; Salicylates; Sensitivity and Specificity; Uranium

Simple water-soluble lanthanum and europium complexes are effective at detecting neutral sugars as well as glycolipids and phospholipids. In solutions at physiologically relevant pH the fluorescent lanthanum complex binds neutral sugars with apparent binding constants comparable to those of arylboronic acids. Interference from commonly occurring anions is minimal. The europium complex detects sialic acid-containing gangliosides at pH 7.0 over an asialoganglioside. This selectivity is attributed, in large part, to the cooperative complexation of the oligosaccharide and sialic acid residues to the metal center, based on analogous prior studies. In MeOH, lysophosphatidic acid (LPA), a biomarker for several pathological conditions including ovarian cancer, is selectively detected by the europium complex. LPA is also detected via a fluorescence increase in human plasma samples. The 2-sn-OH moiety of LPA plays a key role in promoting binding to the metal center. Other molecules found in common brain ganglioside and phospholipid extracts do not interfere in the ganglioside or LPA fluorescence assays.

Topics: Biomarkers, Tumor; Carbohydrate Sequence; Europium; Female; Fluorescent Dyes; Gangliosides; Humans; Hydrogen-Ion Concentration; Lanthanum; Lysophospholipids; Methanol; Molecular Sequence Data; Neoplasms; Ovarian Neoplasms; Salicylates

Stopped-flow kinetic studies of a HSX-Mn-SalophOMe (1) catalyst provide spectroscopic evidence for the direct generation of a manganese(V) oxo salophen from a manganese(III) perbenzoate. The O-O bond heterolysis reaction that produces the oxo is not facilitated by intramolecular proton transfer from the acid hanging group of the HSX platform. Instead, the hanging group stabilizes the catalyst against oxidative degradation and, consistent with recent predictions of theory, is geometrically matched to promote the end-on coordination of a H2O2 substrate prior to its oxidation at the manganese(V) oxo center.

Topics: Catalysis; Kinetics; Manganese; Molecular Structure; Oxygen; Salicylates

We report here a modular approach for the construction of a new class of compounds, the Hangman salophens. In the Hangman motif, an acid-base functionality "hangs" over the face of a redox cofactor. In contrast to more synthetically intractable porphyrin-based Hangman systems, Hangman salophens permit the facile control of their proton and redox properties for the study of the proton-coupled electron transfer (PCET) activation of small molecules. By investigating the catalase-like disproportionation of H2O2, we show that the presence (1) of a strong proton-donating hanging group (i.e., carboxylic acid) and (2) of electron-donating groups on the redox-active salen imparts significant catalytic activity for the O-O bond activation of small molecule substrates. The contribution of the new ligand framework to furthering our understanding of how PCET can be implemented in the design of active/selective catalysts will be discussed.

Topics: Catalase; Catalysis; Electrochemistry; Ligands; Oxidation-Reduction; Salicylates; Xanthenes

Whereas the parent uranyl salophen is catalytically inactive, its phenyl derivative effectively catalyses with turnover the reaction of benzoquinone with 1,3-cyclohexadiene, while showing no appreciable affinity towards reactants and product.

Topics: Benzoquinones; Catalysis; Ketones; Kinetics; Molecular Structure; Organometallic Compounds; Phase Transition; Salicylates

Described are the design, synthesis, and study of nonbiological molecules based on salophen and salen ligands that fold into single-stranded helices in the presence of either Ni(II) or Cu(II). X-ray diffraction studies show that the materials fold into helical structures in the solid state, and a series of NMR studies provide strong evidence that the folded structures are conserved in solution. Metal coordination is required for folding, as NMR and X-ray show that the free ligands do not adopt helical structures. Two of the racemic metallofoldamers spontaneously resolve during crystallization from CHCl3/acetonitrile, and CD spectroscopy and optical rotation show that the resolved, crystalline materials racemize quickly when dissolved at 5 degrees C. This shows that the secondary structures can reorganize easily and can, therefore, provide the basis for responsive materials. By comparison, an analogue from enantiomerically pure (R,R)-(-)-trans-cyclohexanediamine showed a strong CD signal and a large specific rotation. Electrochemical experiments show that a structural reorganization occurs upon metal-centered reduction of a Cu(II)-containing foldamer. When the reduction is carried out in the presence of coordinating ligands, it is proposed that apical binding of those ligands gives square pyramidal complexes. Semiempirical (AM1) calculations support that the helical structure would be disrupted by the reduction to Cu(I) with concomitant reorganization to a square pyramidal complex.

Topics: Biomimetic Materials; Cations, Divalent; Copper; Electrochemistry; Ethylenediamines; Magnetic Resonance Spectroscopy; Metalloproteins; Models, Molecular; Molecular Conformation; Nickel; Organometallic Compounds; Salicylates

[structure: see text] A flipping motion rapidly inverts the bent structure of uranyl-salophen compounds and, consequently, causes fast enantiomerization of nonsymmetrically substituted derivatives. This process has been previously slowed by introducing bulky substituents in the imine bond region. Since the resulting complexes dissociate upon chromatographic treatment, an alternative approach to the design and synthesis of robust, nonflipping uranyl-salophen compounds is here described. Such an approach is based on the idea that the flipping motion would be blocked by connecting the para positions with respect to the phenoxide oxygens by means of polymethylene bridges of suitable length. Analysis of a number of uranyl-salophen compounds by molecular mechanics, while showing that bulky substituents in the imine bond region cause severe distortions of the ligand backbone, suggested that the best chain lengths are those that fit the gap between the phenoxide rings without altering the natural geometry of the parent uranyl-salophen compound. Calculations showed that such chains are those composed of 12 and 13 methylene units. Accordingly, chiral uranyl-salophen macrocycles bridged with 12- and 13-methylene chains were synthesized in fairly good yields and resolved by chiral HPLC.

Topics: Computer-Aided Design; Crystallography, X-Ray; Macrocyclic Compounds; Models, Molecular; Molecular Structure; Organometallic Compounds; Salicylates; Stereoisomerism; Time Factors

A novel member of a new class of chiral uranyl-salophen complexes has been synthesised. The chiral recognition ability of this receptor toward the enantiomers of two primary amines, a sulfoxide, and a quaternary ammonium chloride has been evaluated for the first time. The enantioselectivities obtained are encouraging. The NMR method developed for this purpose allows a fast, quantitative determination of the enantioselectivity of the host directly from its racemic mixture and could find application as a preliminary screening tool in the search for new receptors using combinatorial methods. The experiments carried out in this context demonstrated also that the activation barrier for the racemisation of such chiral uranyl-salophen receptors is much higher than the lower limit of 21 kcal mol(-1) previously reported.

Topics: Benzophenones; Magnetic Resonance Spectroscopy; Models, Molecular; Organometallic Compounds; Phenethylamines; Salicylates; Stereoisomerism; Sulfoxides

A chemically modified electrode constructed by incorporating N,N(')-bis(salicylidene)-1,2-phenylenediaminocobalt(II) into carbon-paste matrix was used as a sensitive electrochemical sensor for detection of cysteine. The resulting electrode exhibits catalytic properties for the electrooxidation of cysteine and lowers the overpotential for the oxidation of this compound. The faster rate of electron transfer results in a near-Nernstian behavior of the modified electrode and makes it a suitable potentiometric and voltammetric sensor for the fast and easy determination of cysteine. A linear response in concentration range from approximately 2 microM to 0.01 M was obtained with a detection limit of 1 microM for the potentiometric detection of cysteine. The modified electrode was also used for the amperometric and differential pulse voltammetric determination of cysteine and the results were compared with those of the potentiometric method.

Topics: Carbon; Cobalt; Cysteine; Electric Conductivity; Electrochemistry; Electrodes; Potentiometry; Salicylates

The base induced addition of benzenethiol to 2-cyclohexen-1-one and its 4,4-, 5,5- and 6,6-dimethyl derivatives is catalysed by a salophen-uranyl based metallocleft 2 in chloroform solution with high turnover efficiency and low product inhibition. Analysis of rate data coupled with equilibrium measurements for complexation of the catalyst with the enone reactants and addition products shows that the catalytic mechanism involves the three main steps typical of single-substrate enzymatic processes, namely substrate binding and recognition, transformation of the bound substrate, and release of the reaction product. Unlike the reference salophen-uranyl 1, catalyst 2 is endowed with a structured binding site responsible for a high degree of substrate specificity among the investigated enones, due to recognition of their shape and size.

Topics: Antinematodal Agents; Binding Sites; Binding, Competitive; Catalysis; Cyclohexanones; Enzymes; Kinetics; Organometallic Compounds; Phenols; Salicylates; Substrate Specificity; Sulfhydryl Compounds; Titrimetry; Uranium

Mn(III)-salophen complex with superoxide scavenging activity was prepared from manganese(III) acetate dihydrate and salophen in ethanol. Visible absorption spectrum of the red-brown complex exhibits a shoulder at 430 nm which was absent with either salophen or manganic acetate alone. Titration of salophen with manganese(III) is consistent with a 1:1 Mn to salophen stoichiometry of the complex based on changes in the absorbance at 500 nm or of superoxide scavenging activity. The superoxide dismutase (SOD)-like activity of the complex in the xanthine-xanthine oxidase/cytochrome c assay was 1450 units/mg salophen. The SOD activity of the complex was suppressed 50% in the presence of EDTA (1 mM), but was not altered in the presence of bovine serum albumin (1 mg/ml) or crude protein extract of Escherichia coli QC779 sodA-sodB- (1 mg/ml). E. coli QC779 sodA-sodB- grew scantily after an 8-h lag phase in aerobic M63 glucose minimal medium. The aerobic growth of the E. coli SOD double mutant in glucose minimal medium was greatly enhanced in the presence of 5 or 10 microM Mn-salophen complex compared to that of control after 24 h incubation. Mn-desferal green complex (10 microM) and pink complex (5 microM) also increased growth rate of E. coli QC779 sodA-sodB- but to a lesser extent than Mn-salophen complex. However, the growth was completely inhibited by 50 microM Mn-salophen complex, 100 microM Mn-desferal green complex, or 10 microM Mn-desferal pink complex.

Topics: Aerobiosis; Deferoxamine; Dose-Response Relationship, Drug; Escherichia coli; Free Radical Scavengers; Manganese; Organometallic Compounds; Salicylates; Spectrophotometry; Superoxide Dismutase; Superoxides