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A novel efficient differential pulse voltammetric (DPV) method for determination gallic acid (GA) was developed by using an electrochemical sensor based on [Cu(2)tpmc](ClO4)(4) immobilized in PVC matrix and coated on graphite (CGE) or classy carbon rod (CGCE). The proposed method is based on the gallic acid oxidation process at formed [Cu(2)tpmcGA](3+) complex at the electrode surface. The complexation was explored by molecular modeling and DFT calculations. Voltammograms for both sensors, recorded in a HNO3 as a supporting electrolyte at pH 2 and measured in 2.5 x 10(-7) to 1.0 x 10(-4) M of GA, resulted with two linear calibration curves (for higher and lower GA concentration range). The detection limit at CGE was 1.48 x 10(-7) M, while at CGCE was 4.6 x 10(-6) M. CGE was successfully applied for the determination of the antioxidant capacity based on GA equivalents for white, rose and red wine samples. This is the peer-reviewed version of the following article: Petković, B. B.; Stanković, D.; Milčić, M.; Sovilj, S. P.; Manojlović, D. Dinuclear Copper(II) Octaazamacrocyclic Complex in a PVC Coated GCE and Graphite as a Voltammetric Sensor for Determination of Gallic Acid and Antioxidant Capacity of Wine Samples. Talanta 2015, 132, 513–519. [https://doi.org/10.1016/j.talanta.2014.09.025] Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3364]

The aim of the present work was to elucidate the binding mechanism and kinetics of anionic cyanine dye 3,3-disulfopropyl-5,5-dichlorothiacyanine sodium salt (TC) J-aggregation on the surface of silver nanoparticles (AgNPs, particle size similar to 6 nm). The hybrid J-aggregateAgNPs assembly was characterized by TEM analysis, UVvis spectrophotometry, and fluorescence measurements. In the elucidation of TC binding on the surface of AgNPs, they were considered as macromolecules with several binding sites and TC dye was considered as a ligand. Scatchard and Hill analysis revealed that TC binding was a random process rather than cooperative, with similar to 200 bonded TC molecules per AgNP and a binding constant K-a = 4.8 x 10(7) M. The TC-AgNP assembly exerted concentration-dependent fluorescence quenching properties. The linearity of the SternVolmer relation, accounting for both static and dynamic quenching, indicated that only one type of quenching occurred, suggesting that AgNPs quenched the fluorescence of TC with an extraordinarily high SternVolmer constant (KSV) in the range of 10(8) M-1. Additionally, the kinetics of J-aggregation of TC in the presence of AgNPs was studied using a stopped flow technique. Kinetic measurements were performed as a function of the TC and AgNP concentration, yielding sigmoidal kinetic curves. The concentration dependence of the parameters of the kinetic curves indicated that J-aggregate formation on the AgNP surface occurred via a two-step process; the first was adsorption of the initial dye layer, followed by the growth of consecutive layers.

Nanoparticles (NPs) modified with fluorescent cyanine dyes can exhibit fluorescent quenching properties due to energy and/or electron transfer, and these systems have many applications in catalysis, drug delivery, nanoelectronics, medical diagnostics, and chemical sensing. The aim of this work was to investigate the adsorption of cyanine dye 5,5-disulfopropyl-3,3-dichlorothiacyanine (TC) on the surface of citrate capped gold nanoparticles (AuNPs) with the average core sizes of 9, 17, and 30 nm using various experimental techniques. The measurements of fluorescence corrected for inner filter effects (IFE) of the particle dye assembly clearly indicated that the fluorescence of TC was quenched by AuNPs on the concentration dependent 3 manner, and the equilibrium constants for the sorption of TC on the NP surface were calculated. Significant increase of fluorescence quenching was noticed when NP size increased, keeping the concentration of NPs of different size constant. By comparing experimental and calculated results for quenching of TC dye fluorescence, we assumed that the maximum quenching was restricted to full monolayer coverage of TC on the NP surface. The conclusion was drawn that the most probable orientation of TC dye molecules on the NP surface was slanted and that the dye approached NP surface with its positively charged thiazole ring.

The complexation reactions between octaazamacrocyclic ligand N,N',N '',N'"-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and Co2+, Ni2+, Zn2+ and Cu2+ metal cations have been studied conductometrically in acetonitrile and aqueous solutions. The conductance data exhibit different stoichiometry of the complexes in two studied solutions. In most cases 1:1 (ML) complexes were formed while in some cases 2:1 (M2L) complexes are evident. The stability constants of the resulting 1:1 complexes were determined by computer fitting of the conductance/mole ratio data. Theoretical DFT calculations were used to explain metal binding capability of tpmc ligand and the binding sequences were found to follow the order: Cu2+ gt gt Ni2+ gt Co2+ gt Zn2+. The combination of results obtained by this theoretical approach and conductometric study successfully explains sensitivity and selectivity of recently developed tpmc based ISE and could play a guiding role in planning experiments with large macrocyclic ligands. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3473]

Phenothiazines are a large group of heterocyclic, aromatic molecules with nitrogen and sulphur between two benzene rings. Their derivatives, N-alkylphenothiazines have supstitutient on heterocyclic nitrogen atom which gives them different properties. Also, a series of these molecules have substitution on carbon atom at place 2 of phenothiazine benzene ring. Alkylphenothiazines contain aminoalkyl substituent and their alkyl, acyl and sulphonil derivatives, as well as monocyclic and bicyclic heterocycles attached at thiazine nitrogen atom or directly linked to benzene ring. The N-alkylphenothiazines have been known as antipsychotic drugs, but they also possess antibacterial, antifungal, anticancer activity, and ability to react with macromolecules and to coordinate to the metals. Metal complexes with N-alkylphenothiazines are biological active compounds with different antimicrobial activities and cytotoxic effect against tumor cell lines. Their large field of application of N-alkylphenothiazines is very attractive in terms of synthesis of new related derivatives, metal complexes, studying their properties and applications. This article presents a review of the literature and a contemporary view at N-alkylphenothiazines - their synthesis and application, as well as their metal complexes which have promising biological effects. [Projekat Ministarstva nauke Republike Srbije, br. 172014]

Mixed ligand dinuclear copper(II) complexes of the general formula [Cu2(Rdtc)tpmc)](ClO4)3 with octaazamacrocyclic ligand tpmc and four different heterocyclic dithiocarbamate ligands Rdtc-, as well as the complexes [Cu2(tpmc)](ClO4)4 and [Cu(tpmc)](ClO4)2 center dot 2H2O were studied in aqueous NaClO4 and HClO4 solutions by cyclic voltammetry on glassy carbon electrode. The electrochemical properties of the ligands and Cu(II) complexes were correlated with their electronic structure. Conductometric experiments showed different stoichiometry in complexation of tpmc with Cu2+ ions and transport of ions in acetonitrile and in aqueous media. These studies clarified the application of this macrocyclic ligand as ionophore in a PVC membrane copper(II) selective electrode and contributed elucidation of its sensor properties.

The kinetics of J-aggregate assembly on the surface of noble metal nanoparticle colloids are described, providing new mechanistic insight into the interaction of the dye molecules with the surface of metal nanoparticles. We specifically studied the J-aggregation of a thiacyanine dye (TC, 3,3′-disulfopropyl-5,5′-dichlorothiacyanine sodium salt) on the surface of gold nanoparticle colloids. The hybrid J-aggregate–Au colloidal dispersions were characterized by UV–vis spectrophotometry, fluorescence measurements, zeta potential measurements, and TEM analysis. Kinetic measurements were carried out using a stopped-flow method, indicating that the J-aggregate formation on the surface occurs via a two-step process. The first step includes adsorption of the initial dye layer, followed by an order of magnitude slower growth of consecutive layers. Activation parameters determined from the fluorescence measurements yielded further details about the nature of the interaction.

The thermal decomposition of [RuCl2(eta(6)-p-cymene)](2) (1) and its biologically active N-alkylphenothiazine compounds of composition L[RuCl3(eta(6)-p-cymene)] where L = CPH+ (2), TFH+center dot HCl (3), and TRH+ (4) (chlorpromazine hydrochloride, CP center dot HCl; trifluoperazine dihydrochloride, TF center dot 2HCl; and thioridazine hydrochloride, TR center dot HCl, respectively) has been studied. The crystal and molecular structure of compound 3 was determined earlier by single crystal X-ray diffraction analysis. The thermal data were collected by simultaneous TG/DSC measurements. For evolved gas detection, the qualitative reaction of chlorides with AgNO3 in an acidic solution was applied. The measurements were carried out in the temperature range to 700 A degrees C in nitrogen atmosphere. Compounds of L[RuCl3(eta(6)-p-cymene)] crystallize with water or water/2-propanole. On the basis of thermal data, the trend in the solvent bonding energies was assessed.

Thermal decomposition of chlorpromazine hydrochloride (CP center dot HCl), trifluoperazine dihydrochloride (TF center dot 2HCl) and thioridazine hydrochloride (TR center dot HCl), and the ruthenium complexes with dimethyl sulfoxide (dmso) of composition [RuCl(2)(dmso)(4)] and L[RuCl(3)(dmso)(3)]center dot xEtOH, L = CP center dot HCl, TF center dot 2HCl or TR center dot HCl is described. The phenothiazines are stable to temperature range of 200-280 A degrees C with an increasing stability order of TF center dot 2HCl < CP center dot HCl < TR center dot HCl. The decomposition of all the compounds takes place in superposing steps. For detection of chlorides and sulfides, EGD analysis was performed. The decomposition pattern of the complexes, due to their similar structure, is similar. The thermal data unambiguously resolve the contradiction between the elemental analysis and X-ray structural data for (TF center dot 2HCl)[RuCl(3)(dmso)(3)]Cl center dot EtOH. The compound crystallizes with one EtOH, evaporating in part at room temperature.

The simple PVC-based membrane containing N',N',N '',N '''-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) as an ionophore and dibutyl phthalate as a plasticizer, directly coated on a glassy carbon electrode was examined as a new sensor for Cu2+ ions. The potential response was linear within the concentration range of 1.0x10(-1)-1.0 x 10(-6)M with a Nernstian slope of 28.8 mV/decade and detection limit of 7.0 x 10(-7)M. The electrode was used in aqueous solutions over a wide pH range (1.3-6). The sensor exhibited excellent selectivity for Cu2+ ion over a number of cations and was successfully used in its determination in real samples.

Platinum electrode decorated with three different mixed-ligand cobalt(III) complexes of the general formula [Co(Rdtc)cyclam](ClO4)(2) [cyclam = 1,4,8,11-tetraazacyclotetradecane, Rdtc(-) = morpholine-(Morphdtc), piperidine-(Pipdtc), and 4-methylpiperidine-(4-Mepipdtc) dithiocarbamates, respectively] was used to study oxidation of formic acid in acidic solution. The complexes were adsorbed on differently prepared Pt surfaces, at open circuit potential. The preliminary results show increased catalytic activity of Pt for formic acid oxidation with complex ion adsorbed on the polycrystalline surfaces. The increase in catalytic activity depends on the structure of the complex applied and follows the order of metal-coordinated bidentate ligand as Morphdtc > Pipdtc > 4-Mepipdtc. Based on IR and NMR data, the main characteristics of the Rdtc ligands do not vary dramatically, but high symmetry of the corresponding complexes decreases in the same order. Accordingly, the complexes are distinctively more mobile, causing chemical interactions to occur on the surface with appreciable speed and enhanced selectivity. The effect of the complexes on catalytic activity presumably depends on structural changes on Pt surfaces caused by their adsorption.

The reactions of cisplatin with nizatidine and ranitidine were studied in D2O at pD 7.4 and 298 K by means of 1H NMR spectroscopy. The second order rate constants, k2, for the reaction of cisplatin with nizatidine is (2.71 ± 0.11) × 10−4 M−1 s−1, and for the reaction with ranitidine (6.72 ± 0.17) × 10−4 M−1 s−1. The reactions of nizatidine and ranitidine were also studied with other Pd(II) and Pt(II) complexes. The set of the complexes was selected because of their difference in reactivity, steric hindrance, and binding properties.

The influence of cationic surfactant hexadecyltrimethylammonium bromide (CTAB) on the kinetics of the spontaneous reduction of the analytically important compound, sodium hexanitrocobaltate(III), was studied. The spontaneous reduction was monitored spectrophotometrically at pH 2 and 5 and at concentrations of CTAB from 1 x 10(-5) to 5 x 10(-4) M. The mechanism of this process was described using two consecutive first-order reactions. A decrease in the rate constant for reduction at pH 5 in solutions containing CTAB in concentrations of 5.6 x 10(-5) M (critical micelle concentration) compared with its rate in an aqueous solution was observed. These effects could be explained by electrostatic and hydrophobic/hydrophilic interactions between the micellar pseudophase and the hexanitrocobaltate(III) ion.

Isatin-3-thiosemicarbazone complexes with Co(II), Ni(II), Cu(II), Zn(II), Hg(II) and Pd(II) were synthesized and evaluated for their antimicrobial activity against 7 pathogenic bacteria and 4 fungi. The complexes have an en?hanced activity compared to the ligand due to transition metal involved in coor?dination. The anti-amoebic activity in vitro was evaluated against the HM1:IMSS strain of Entamoeba histolytica and the results were compared with the standard drug, metronidazole. The preliminary test results showed that the complexes had better anti-amoebic activity than their respective ligands. Moreover, the com?plexes showed better inhibition of the test organism.

In silico model of title drugs mode of interaction with Cu2+ ion was proposed. A hundred conformations of each drug are used in this study. Examination of drugs interactions with Cu2+ ion were conducted using GRID package. The Cu2+ probe was used. The two favorable regions of interactions were detected: a) the nitro group and terminal imino nitrogen in a γ position from it, as proposed from the experimental data, b) the region of heterocyclic ring (tiazoline and furan from Nizatidine and Ranitidine, respectively) as the most favorable one. Therefore, the present study identifies the second region of the molecule that is able to strongly interact with the Cu2+ ion. The position and energies of obtained molecular interaction fields (MIF) are discussed. The results support the fact that the properties, which express recognition forces of the molecules, are strongly dependent on 3D geometry.

The inhibiting effect of cobalt(III) complexes with macrocyclic ligand cyclam (1,4,8,11-tetraazacyclotetradecane) and β-diketonato ligands have been investigated on iron corrosion in 0.1 M HClO 4 by potentiodynamic, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) measurements. Analysis of the polarization curves and impedance spectra, by adding complex compounds to the acid solution and comparing with inhibitor-free solution, show corrosion current decrease and charge transfer resistance increase, respectively. Impedance data are fitted with equivalent circuit models. The stability of the adsorbed film was followed by LPR. Scanning electron microscopy (SEM) was used to screen physical changes of the reacted surfaces both treated and untreated. The differences in inhibitor efficiencies depend on the substituent group of the coordinated β-diketone ligand. Structural and electronic properties of this group of compounds in relation to inhibitor efficiency were analyzed by using the molecular modeling structures and correlated with previously reported spectroscopy data.

A huge variety of nano-objects, allowing specific reactions at well-defined positions can be generated using oxo-molybdenurn compounds based building blocks and fragments. On the other side, the use of suphur-based interfaces as metal-based organic materials is a new area with many potential applications in medicine, particularly as implants. In that respect, as precursors for building new materials with pronounced characteristics five new dioxomolybdenum(VI) complexes of the general formula [MoO2(RdtC)(2)] have been used in the present work. Their predicted geometries optimized by the MO calculations are in excellent agreement with the reported crystal structure data, and therefore can be used as models for docking study between complexes and biomolecules. In silico screening for complex-protein interaction will be able to predict behavior of such materials implanted in living systems. Recent Developments in Advanced Materials and Processes, 7th Conference of the Yugoslav-Materials-Research-Society (Yu-MRS), Sep 12-16, 2005, Herceg Novi, Montenegro

The mass spectral fragmentation of five dinuclear Cu(II) complexes of the general formula [Cu2(Rdtc)tpmc] (ClO4)3, where tpmc and Rdtc refer to N, N′, N″, N‴-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane and piperidine- (Pipdtc), 4-morpholine- (Morphdtc), 4-thiomorpholine- (Timdtc), piperazine- (Pzdtc), or N-methylpiperazine- (N-Mepzdtc) dithiocarbamates, respectively, has been investigated. The results were shown to be of mechanistic significance, clarifying the major products of their fragmentation. A possible mechanism entails a multi-step decomposition process that can be separated into individual steps depending on their molecular structures. Every step is determined to some extent by the nature of the intermediates.

Five new CuII complexes of general formula [Cu2(Rdtc)tpmc](ClO4)3, (1)–(5), where tpmc and Rdtc − refer to N,N′,N′′,N′′′-tetrakis(2-pyridylmethyl)-1,4,8,11-teraazacyclotetradecane and piperidine- (Pipdtc), 4-morpholine- (Morphdtc), 4-thiomorpholine- (Timdtc), piperazine- (Pzdtc) or N-methylpiperazine- (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. Elemental analyses, conductometric and magnetic measurements, u.v./vis, i.r., e.p.r. and mass spectroscopy have been employed to characterize them. The complexes adopt an exo coordination of CuII ions and tpmc. The dithiocarbamate ion joins both the sulphur and the copper atoms acting as a bridging ligand The presence of different heteroatoms in the piperidine ring influences the ν(C=N) and ν(C=S) vibrations which decrease in the order of the complexes: Pipdtc > N-Mepipdtc > Pzdtc > Morphdtc > Timdtc ligands. Attention has been paid to the detailed mechanism of the mass spectral fragmentation of the complexes. The g eff factors of the complexes have been also estimated by e.p.r. spectra. Finally, the complexes obtained demonstrate microbiologycal activity against some bacteria.

The syntheses of a new ligand 2-(diphenylphosphino)benzaldehyde selenosemicarbazone (HL) and the corresponding complex with Ni(II) of the formula [Ni(L)(NCS)] are reported. The complex was characterized by single crystal X-ray analysis. The compound complex is diamagnetic and has a markedly deformed square-planar structure with PNSe set of donor atoms of the ligand, the Schiff base monoanion, and the N atom of the coordinated NCS group. The phosphorus atom deviates even by 0.494(3) Angstrom from the mean plane defined by the other coordination atoms (NSeN) and the metal atom. (C) 2003 Published by Elsevier B.V.

Electrochemical stability of eight complexes of the general formula [co 111 Rdtc(1-8)cyclam](ClO 4 ) 2 , where cyclam=1,4,8,11-tetraazacyclotetradecane and Rdtc - (1-8)=4-morpholine (Morphdtc), 4-thiomorpholine (Timdtc), 4-piperazine (Pzdtc), N-methyl piperazine (N-Mepzdtc), piperidine (Pipdtc), 2-, 3- or 4-methylpiperidine (2-, 3- or 4-Mepipdtc) dithiocarbamates, respectively, were studied. The substances were examined in aqueous NaClO 4 solution and nonaqueous LiClO 4 in CH 3 CN solution by cyclic voltammetry. In aqueous solution, macrocyclic ligand cyclam is characterized by the anodic peak at 0.95 V. The Rdtc - ligands have two anodic peaks, one in the region 0.25-0.30 V and the other in the 0.78-0.95 V region. Absence of these anodic peaks in the case of the complexes indicates that coordination to cobalt(III) stabilizes both cyclam and Rdtc - ligands, but reversible peaks in the range -0.68 to -0.78 V support the Co(III) redox reaction. In nonaqueous solutions cyclam has one anodic peak at 1.75 V. The ligands with heteroatom in the ring (Morphdtc, Timdtc, Pzdtc, N-Mepzdtc) have two anodic peaks, while the other four ligands (Pipdtc, 2-, 3- and 4-Mepipdtc) have only one anodic peak. In nonaqueous solution again, coordination to Co(III) ion stabilizes the Rdtc - ligands and contrary to aqueous solution no Co(III) redox reaction occurs, indicating a greater stability of the complexes in this media. Finally, the electrochemical results are compared with spectroscopic data obtained previously.

The thermal properties of four copper(II) complexes with N , N ′, N ″, N ‴-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and several bidentate ligands N,S (thiosemicarbazide and thiourea) or N,O donors (semicarbazide and urea), of the general formula [Cu 2 (X)tpmc](ClO 4 ) 4 , have been investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). The thermal stability order can be recognized for the examined complexes, depending on coordinated bidentate bridging N,S or N,O ligand. Kinetic data demonstrated first-order thermal decomposition. A plausible mechanism has been proposed which explains the major products of the degradation.

Calculation of the magnetic susceptibility of Co 2+ pairs in the recently synthesized cobaltous cluster complex [Co 2 (ox)tpmc](ClO 4 ) 2 ·3H 2 O has been conducted by the use of two different theoretical models. The calculated results were compared to the experimental data collected in a wide temperature region. Conclusions on both the magnetic properties of Co 2+ dimers and the validity of the proposed models have been drawn. In the temperature region above χ ( T ) maximum, the best results are obtained with the Heisenberg model that includes spin–orbit coupling and excited single-ion levels. In the low-temperature region anisotropy of the magnetic properties dominates and Ising dimer ground-state model gives a more appropriate description. Obtained g -values ( g ∥ a =5.67, g ∥ b =5.73, and g ⊥ =1.54) confirm strong Co 2+ anisotropy. Each model gives the same value of the intracluster exchange integral J/k B ≈−14.6 K , within the fitting error.

Four new mixed complexes of Co(II) with N,N′ N″,N′″-tetrakis(2-pyridylmethyl)-1, 4, 8, 11-tetraazacyclotetradecane (tpmc) and bridged α- or β-aminocarboxylato ligands of general formula [Co2(Y)tpmc](C1O4)3 zH2O where Y = glycinato, S-alaninato, S-aminobutyrato, β-aminobutyrato ion, and z = 0, 0.5 or 1 were isolated. The complexes were characterised by elemental analysis, electronic and IR spectroscopy, magnetic measurements and cyclic voltam-metry. A structure with μ-O, O′-coordination of the aminocarboxylato ligand, and exo coordination of Co(II) ions and tpmc is proposed. The complexes exhibit different electrochemical activities; glycinato and S-alaninato complexes are electrochemically active, whereas S-aminobutyrato and β-aminobutyrato complexes are electrochemically inactive under the given conditions.

The effect of the substituents, solvent polarities and hydrogen ion concentration on the electronic structure and UV/VIS absorption spectra of some Schiff bases, derivatives of N-(R-benzylidene)benzidine (R = o-NO2 and o-OH, p-OH) and N-(R-furfurylidene)benzidine (R = H and 5 - NO2), have been studied. The spectral shifts obtained in various organic solvents were discussed on the basis of the specific solute - solvent interactions through the formation of hydrogen bonds between hydrogen-bond donor (HBD) solvents and the benzidine nitrogen atom of the Schiff bases. Some interpretations of the electronic aspects of this type of hydrogen bonding were discussed as well as the stabilization effects due to the solvation. Finally, the pK values of the compounds were determined.

Two new dinuclear cobalt(II) complexes which, besides macrocyclic ligand N′,N′,N″,N‴-tetrakis (2-pyridylmethyl)-l,4,8,11-tetraazacyclotetradecane (tpmc) contain α- or β-aminoisobutyrato ions (α-aibu − and β-aibu −, respectively) were synthesized. The complexes having general formula [Co2(aibu)tpmc](CIO4)3 were characterized by elemental analysis, electronic and 1R spectroscopy, magnetic measurements and cyclic voltammetry. It was assumed that in both complexes an exo coordination of the macrocyclic ligand is achieved. Cobalt(II) ions are bridged with O,O′-aminoisobutyrato ligand. Both complexes are stable against air oxidation, whereas the oxidation of the complex containing the α-aibu− ion by hydrogen-peroxide gave the coresponding mixed-valence Co11/Co111 complex. The complexes are also electrochemically stable in the potential range from-0,6V to 0,4V vs SCE.

Two new platinum(IV) complexes (1, trifluoperazinehydrochloride-aquapentachloridoplatinate(IV) and 2, chlorpromazine-chlorpromazinehydrochloridepentachloridoplatinate(IV)) were synthesized in the reaction of K-2[PtCl6] with trifluoperazine dihydrochloride (TF center dot 2HCl) or chlorpromazine hydrochloride (CP center dot HCl). The complexes were characterized by elemental analysis, molar conductivity measurement, and spectral (IR, H-1, C-13, 2D H-1-C-13 heteronuclear correlation spectra, Pt-195 NMR, and MS) methods. Outer-coordination sphere was proposed for 1; while in 2, the ligand was coordinated to the metal. The complexes exhibit antibacterial effect on strains of Bacillus subtilis, Bacillus cereus, Bacillus pumilus, and methicillin-resistant Staphylococci as Gram-positive bacteria and an Escherichia coli as Gram-negative bacteria, as well as the reference strains. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3513]

The aim of this work was to investigate the formation of J-aggregates of thiacyanine dye (TC, 5,5′-disulfopropyl-3,3′-dichlorothiacyanine sodium salt) in the presence of 6 nm spherical silver nanoparticles (Ag NPs) using spectrophotometric and fluorescence methods. The formation of J-aggregates was concentration dependent and characterized by the appearance of the new absorption band with the maximum at 481 nm. Spectrophotometric study of J-aggregate formation and time stability suggested that they were formed on the account of monomer form of TC. Moreover, the stability of J-aggregates increased with the lowering AgNPs concentration. The measurements of fluorescence of the NPs—dye assembly clearly indicated that the fluorescence of TC was quenched by Ag NPs on the concentration dependent manner. The spectrophotometric and fluorescence properties of NPs—dye assembly were found to be quantitatively related to the surface coverage of the dye on the Ag NPs.

Three new ruthenium(II) complexes 1-3 containing N-alkylphenothiazine molecules were synthesized by reaction of [RuCl2(eta(6)-P-cymene)](2) with chlorpromazine hydrochloride (1), trifluoperazine dihydrochloride (2) or thioridazine hydrochloride (3). The compounds of the general formula L[RuCl3(eta(6)-p-cymene)] were characterized by elemental analysis and spectroscopic methods (FT-IR, UV-Vis, H-1 and C-13 NMR). Complex 2 was structurally characterized by single crystal X-ray diffraction. In vitro cytotoxic activity of complexes 1-3 were assayed in four human carcinoma cell lines MCF-7, MDA-MB-453 (breast carcinoma), SW-480 (colon carcinoma) and IM9 (myeloma multiple cells). The highest cytotoxicity (12.1 lt = IC50 lt = 17.3 mu M) and induced a total (SW-480) or almost total cell death (MCF-7. MDA-MB-453) at 25 mu M in 48 h of treatment were observed for complex 2. The influence of three different doses (0.4, 4.5 and 90.4 mu M/kg bw) of complex 2 on activities of antioxidants enzymes (superoxide dismutase (SOD) and catalase (CAT)) and lactate dehydrogenase (LDH) were investigated under physiological conditions. The effects on nitrite production (NO2-) and level of erythrocytes malondialdehyde (MDA) in rats blood were evaluated, too. (C) 2011 Elsevier Masson SAS. All rights reserved.

An all solid-state Ag(I) ion-selective electrode has been prepared by simply immersing a glassy carbon rod coated with PVCAc, which contained plasticizer and additive but no ionophore, into the AgNO3 solution. The response of the electrode was linear with a Nernstian slope of 60.25 mV/decade within the concentration range from 1 x 10(-1) to 1 x 10(-5) M and with a detection limit of 4.25 x 10(-6)M. The stability as an effect of various cations was defined. The electrode is suitable for use in high acidic solutions (pH LT 1 to 7) and has successfully been applied for the determination of silver(I) concentrations in different samples.

Three new complexes of the general formula L[RuCl(3)(DMSO)(3)] (1-3), where L = chlorpromazine hydrochloride, trifluoroperazine dihydrochloride or thioridazine hydrochloride, were prepared and characterized by elemental analysis and spectroscopic methods (FT-IR, UV-Vis, (1)H NMR and (13)C NMR). In addition, the crystal structure of the complex 2 containing trifluoroperazine dihydrochloride was solved by single crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space group P2(1)/n, with a = 10.4935(7) angstrom, b = 18.6836(12) angstrom, c = 19.9250(13) angstrom, beta = 98.448(2)degrees, V = 3864.0(4) angstrom(3). The structure was refined to the agreement factors of R = 4.79%, R(w) = 11.23%. The effect of three different doses (0.4, 4.5 and 90.4 mu M/kg bw) of complex 2 on superoxide dismutase (SOD) and catalase (CAT) activity was investigated under physiological conditions. Influence on nitrite production (NO(2)(-)) and the level of erythrocytes malondialdehyde (MDA) in rats blood was also evaluated. Complex 2 did not affect the CAT enzyme activity in vivo and did not cause the hydroxyl radicals production. In the 0.4 and 4.5 mu M/kg bw doses it showed almost the same or lower SOD activity and nitrite levels, while the dose of 90.4 mu M/kg bw significantly increased these parameters. Finally, the cytotoxicity of complexes were assayed in four human carcinoma cell lines MCF-7, MDA-MB-453 (breast carcinoma), SW-480 (colon adenocarcinoma) and IM9 (myeloma multiple cells). Antiproliferative activity in vitro with low IC(50) during 48 h of treatment was observed. (C) 2010 Elsevier Masson SAS. All rights reserved.

The reactions between 1,8-dihydroxy-2(imidazole-2-ylazo)-naphthalene-3,6-disulphonic acid (MONO-IACA) with Pd(II), Cu (II) and Ni(II) were studied spectrophotometrically in the acidity range from 3M HClO 4 to pH 8. The reactions involve the formation of [Cu(LH 2 ) 2 ] 4− , [NiLH 2 ] − and [PdLH 4 ] + chelate species with release of protons from imidazole and hydroxy groups. The equilibrium constants for the reaction Me + nLH x ⇄ MeL n H z + H + , log K eg , and stability constants of complexes, β, were determined from spectrophotometric measurements. The theoretical calculations of the complex structures confirmed the reagent acting as tridentate ligand, forming two five membered chelate rings.

The kinetics of the reaction between the tetrachloroaurate(III) ion and L-methionine (L-Met) (0.1 M HClO4, pH 1.0-2.5) have been studied spectrophotometrically using a stopped-flow technique at different temperatures. Initially, the fast substitution reaction was ascribed to the formation of the short-lived square-planar Au(III)-(L-Met) that was followed by the replacement of a Cl- ligand and a subsequent, slower reduction to Au(I)-(L-Met). This is an intermolecular process, involving attack on the [AuCl4](-) Complex by an outer-sphere L-methionine. The activation parameters (Delta H-not equal and Delta S-not equal) for substitution and reduction were determined. IR spectroscopy indicates that L-methionine acts as a bidentate ligand, most likely coordinating via the S and N atoms, while H-1 and C-13 NMR data indicate methionine sulfoxide as the final product. Finally, the components of the reaction were treated thermally in order to investigate the solid phase synthesis of the resulting complex. (C) 2008 Elsevier Ltd. All rights reserved.

1 Introduction 2 Vibrational Spectra 3 UV-vis Spectra 4 NMR Spectra 5 EPR Spectra 6 Mass Spectra 7 Molecular Characteristics and Application Perspectives 8 Acknowledgments Keywords: molecular structure of metal enolates; ligand properties, coordination activity, bond length and orientation of donor atoms - key functions in designing organic structures; enolate ions, intermediates in synthetic organic chemistry; enolic and ketonic forms of acetylacetone; vibrational spectra - IR spectra, spectral technique for detecting β-diketonate moiety and type of bonding; scandium and yttrium diketonates; nickel and palladium diketonates; UV-VIS spectra

The influence of magnetic properties of cathodes on the separation factor and hydrogen evolution process was investigated. The cathodes used in standard electrolyte and in activated one were pure Ni and the electrocatalytic coatings with definite compositions of transition metals on Ni substrate. The obtained correlations between electrocatalytic activity and magnetic properties of the investigated cathode materials issue from their d-electronic configuration. Keywords: Hydrogen reaction, Separation factor, Magnetic properties

Cytotoxicity and cell growth inhibition studies were performed for five distinct cobalt(ll) [Co(2)(acac)tpmc](ClO(4))(3), [Co(2)(dibzac)tpmc](ClO(4))(3), [Co(2)(hfac)tpmc](CIO(4))(2), [Co(2)(tmhd)tpmc](CIO(4))(3) and [Co(2)(ox)tpmc](CIO(4))(2).3H(2)0 and five molybdenum(Vl) complexes, [MoO(2)(pipdtc)(2)], [MoO(2)(morphdtc)], [MoO(2)(timdtc)(2)], [MoO(2)(pzdtc)(2)] and [MoO(2)(N-Mepzdtc)(2)]. The former were tested in two leukemia cell lines: chronic myelogenic leukemia (K562) and human promyelocytic cell line (U937). They showed to have relatively high toxicity in K562 cells and a relatively low cytotoxicity in U937 cells, as assessed by both MTT and Trypan Blue assays. The five molybdenum complexes were tested in human promyelotic U937 cell line and they showed to have high toxicity.

Magnetic properties of the dinuclear cobalt complex [Co-2(ox)tpmc](ClO4)(2).3H(2)O have been studied from the magnetization data obtained in the high magnetic field-low temperature experiment (B less than or equal to 20 T, T = 4.2 K). An excellent agreement between experimental and calculated data was achieved within the framework of the isolated Ising Co(H) pairs in the ground state, where each cobalt ion from the pair was situated in a differently distorted octahedral environment (asymmetric dimer). The obtained values for g-factors, g(a) = (4.5 +/- 0.1) and g(b) = (3.3 +/- 0.1), and for the intracluster exchange integral J = (-16.0 +/- 0.5) K confirm both the previous results on the crystal structure of the complex under consideration and the assumption on the strong antiferromagnetic coupling between cobalt ions realized by the superexchange interaction over the asymmetric oxalato bridge. (C) 2003 Published by Elsevier Science Ltd.

Hydrogen production via electrolysis of water from alkaline aqueous electrolytes is a well-established conventional technology. However, due to high energy requirements of about 4.5-5 kWh/m(n)(3) H-2 in most industrial electrolysers, the cost of hydrogen produced in such a way is n high. This is a limiting factor for the use of this method on a large scale, except in countries where the electricity is very cheap. There were various attempts to improve this process, like zero-gap cell geometry, developmentof new diaphragm materials, development of new electrocatalytic materials for electrodes, etc. We tried here to use ionic activators to reduce energy consumption. Two types of activators, both ethylenediamine complexes of cobalt, were used separately or in combination with some molybdates. The activation energies were significantly decreased in the presence of single ionic activators. However, the best results regarding the activation energy reduction were obtained when combinations with the molybdate were used. On the basis of the results of our experiments there is a strong indication that the activation with ionic activators reduces energy needs per mass unit of hydrogen produced for more than 10% in some cases, compared to those of non-activated electrolytes. (C) 2003 Elsevier Science B.V. All rights reserved. Conference on Scientific Advances in Fuel Cell Systems, Sep 25-26, 2002, Amsterdam, Netherlands

The thermal properties of four cobalt(III) complexes with cyclam (1,4,8,11-tetraazacyclotetradecane) and the heterocyclic dithiocarbamates Rdtc(-) [2-, 3-, 4-methylpiperidine (2-, 3-, 4-Mepipdtc(-)) or 4-thiomorpholine (Timdtc(-)) dithiocarbamates], of the general formula [Co(Rdtc)cyclam](ClO4)(2), have been investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). The thermal decomposition pathways of these complexes were also proposed. The following thermal stability order can be recognized for the examined complexes. depending on the position of the methyl group on the piperidine ring coordinating dithiocarbamates 2- GT 3- GT 4 -Mepipdtc(-). Generally, the same order was found to affect the decrease in kinetic and activation parameters. Trends in Advanced Materials and Processes, 3rd Yugoslov-Materials-Research-Society Conference, Sep 20-24, 1999, Herceg Novi, Yugoslavia

The kinetics of the spontaneous reduction of hexanitrocobaltate(III) ion have been investigated spectrophotometrically (λ=360 nm at 298 K) in ethanol or acetone water mixtures containing 0, 10, 25 and 50 % of organic solvents. The mechanism of this process was expressed by means of two consecutive first-order reactions. Both of the first-order rate constants decrease with the increasing nonaqueous species content. The reduction of hexanitrocobaltate(III) ion in the mixtures was much slower than the corresponding reaction in water.

The aim of the work was to investigate the adsorption of negatively charged cyanine dye 5,5′-disulfopropyl-3,3′-dichlorothiacyanine (TC) on the surface of borate capped gold nanoparticles (AuNPs) with average core sizes of 6 and 10 nm. The characterization of AuNPs in the presence and absence of TC was performed by measurements of the absorption, fluorescence and Raman spectra, TEM, DLS and zeta potential. The measurements of fluorescence of the NPs–TC assembly in the presence of low TC concentration clearly indicated that the fluorescence of TC was quenched by AuNPs in the concentration dependent manner. This process was found to be quantitatively related to the surface coverage of AuNPs by TC molecules. NPs surface coverage by TC was obtained from the dependence of TC fluorescence on NPs or TC concentration, keeping the concentration of one of the components of the NPs–TC assembly constant. The calculated values were obtained under the assumption that the monolayer of TC molecules, which were in direct contact with the NPs surface, was adsorbed. The experimentally obtained values were in accordance with the calculated ones for TC orientation along the vertical short side. The formation of TC J-aggregates was evident only in the presence of 6 nm NPs, when TC concentration was high. In this case the experimentally obtained value for C6 concentration needed to completely quench TC dyes' fluorescence was much lower than the calculated, indicating that the dye was accommodated on the surface of these NPs in more than one layer, and most probably in the slanted configuration.

4-Morpholine-, piperidine-, 4-piperazine- and N-methyl- piperazine-dithiocarbamate complexes of Cobalt (III) with 1, 4, 8, 11-tetraazacyclotetradecane, of general formula [Co(Rdtc)cyclam] (C104)2, have been prepared and have been characterized. The complexes adopt cis-octahedral geometry with folded macrocyclic ligand and with the dithiocarbamate bound as a bidentate. trans-influence of the dithiocarbamate ligands was studied by NMR spectroscopy and established the order piperidine-dtc > 4-morpholine-dtc > N-methyl-piperazine-dtc.