Volume 10, Issue 1

A comprehensive review, >100 references, on organotin(IV) complexes of the carboxylic acid derivatives are presented with special reference to their methods of synthesis, spectroscopic and structural studies and their biological activities. The structures of these complexes are discussed on the basis of IR, multinuclear (1H-, 13C- and 119Sn-) NMR.

Interfacial tension is an important characteristic of a biological membrane because it determines its rigidity, thus affecting its stability. It is affected by factors such as medium pH and by the presence of certain substances, for example cholesterol, other lipids, fatty acids, amines, amino acids, or proteins, incorporated in the lipid bilayer. Here, the effects of various parameters to on interfacial tension values of bilayer lipid membranes are discussed. The mathematically derived and experimentally confirmed results presented in this paper are of importance to the interpretation of phenomena occurring in lipid bilayers. These results can lead to a better understanding of the physical properties of biological membranes. The simple interfacial tension method proposed herein may be successfully used to determine the interfacial tension values of 1:1 lipid-lipid, lipid-cholesterol, lipid-fatty acid, lipid-amine, and lipid-amino acid systems.

Application of Micellar enhanced ultrafiltration (MEUF) for the removal of different heavy metals has been reviewed. It is considered an economical alternative available to the conventional membrane separation process, because it reduces the requirement of higher pressure and high membrane costs. MEUF is a separation processes which uses surfactants and ultrafiltration membranes to remove multivalent ions from wastewater with high percent rejection using electrostatic attraction between metals and micelles. This review seeks to define the effect of the operating parameters, i.e., applied pressure, surfactant concentration, feed temperature, metal ion concentration, feed flow rate, operating time etc. on the removal of metal ions. Emphasis is given to the application of MEUF for the removal of single metal ions, multiple metal ions and different metals along with other organic materials. Also, this review focuses on studies related to micelle formation, attraction between metal ions and micelles, and recovery of surfactants for future research.

The first Mukaiyama-Michael vinylogous reaction of a dioxinone-derived silyl ether to nitroalkenes is reported. The conjugate addition is performed in absence of any catalyst under solvent-free conditions, proceeding with satisfactory efficiency with variously substituted nitroalkenes. Moreover, the first organocatalyzed Mukaiyama-Michael vinylogous reaction of trimethylsilyloxyfuran to nitroalkenes is described.The reaction is promoted by Brønsted acids under solvent-free conditions, taking place in moderate to good yield with variously substituted nitroalkenes..

In this study, we report on a new method for the synthesis of ZnS quantum dots (QDs). The synthesis was carried out at low temperature by a chemical reaction between zinc ions and freshly reduced sulfide ions in ethanol as reaction medium. Zinc chloride and elemental sulfur were used as zinc and sulfur sources, respectively and hydrazine hydrate was used as a strong reducing agent to convert elemental sulfur (S8) into highly reactive sulfide ions (S2−) which react spontaneously with zinc ions. This facile, less toxic, inexpensive route has a high yield for the synthesis of high quality metal sulfide QDs. Transmission electron microscopy (TEM) image analysis and selected area electron diffraction (SAED) reveal that ZnS QDs are less than 3 nm in diameter and are of cubic crystalline phase. The UV-Vis absorption spectrum shows an absorption peak at 253 nm corresponding to a band gap of 4.9 eV, which is high when compared to the bulk value of 3.68 eV revealing strong quantum confinement. PL emission transitions are observed at 314 nm and 439 nm and related to point defects in ZnS QDs.

In the present study, the acid-base equilibria of N,O-carboxymethy chitosan abbreviated as (NOCC), is investigated. The complex formation equilibria with the metal ions Cu(II), Ni(II), Co(II), Mn(II), and Zn(II) are investigated potentiometrically. The stability constant values of the binary and ternary complexes formed in solution were determined and the binding centers of the ligands were assigned. The relationships between the properties of the studied central metal ions as ionic radius, electronegativity, atomic number, and ionization potential, and the stability constants of the formed complexes were investigated in an effort to give information about the nature of chemical bonding in complexes and make possible the calculation of unknown stability constants. Cu(II), Ni(II), and U(VI) complexes with NOCC are isolated as solid complexes and characterized by conventional chemical and physical methods. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies. The ternary copper(II) complexes involving NOCC and various biologically relevant ligands containing different functional groups, as amino acids and DNA constituents are investigated. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated.

In this study, more than 200 samples of drinking water from taps in the Silesian District (southern Poland) were analyzed. Concentrations of As, Bi, Cd, Co, Cr, Mo, Ni, Pb, Rb, Sb, Se, Te, Tl and V were measured using inductively coupled plasma-mass spectrometry technique (ICP-MS). The levels of the tested elements generally met European Union regulations. All analytical results were processed using computational methods, including the Pearson and Gini coefficients with the Lorenz curves, one-way ANOVA, the Kruskal-Wallis one-way analysis of variance, the Mann-Whitney U test, the variance correlation test and the Spearman’s test. In addition, Principal Component Analysis (PCA) with Varimax and Cluster Analysis with Ward’s Method were applied. It was shown, that some parameters (e.g. hardness and alkalinity) were highly correlated. The score plot described the degree of mineralization of water samples, so the origin of water could be easily determined. In turn, based on the created dendrogram, the division of samples into several groups (with soft, medium and highly mineralized water) could be deduced.

The purpose of this article is to emphasize that new nanomaterials offer a number of attractive alternatives for solar energy use in wastewater photocatalysis. The wastewater from the textile industry contains dyes and heavy metals. Thin films of cadmium doped TiO2 (Cd-TiO2) were coated by a doctor blade using TiO2 Degussa P25 and cadmium precursor (cadmium nitrate). The photocatalytic efficiency of cadmium doped TiO2 is strongly influenced by crystal structure, particle size, particle morphology, porosity and doping. The pore size distribution and the roughness analysis have been studied by the atomic force microscopy (AFM) of the thin films. The photocatalytic activity of the samples was tested in Methyl orange and Methylene blue photodegradation. Cadmium doped TiO2 catalyst does not significantly decrease the efficiency of photodegradation processes, and, in some situations, improves dye photodegradation.

Cyclohepta[b]indole derivatives 7 were prepared by subsequent aza-Claisen rearrangement and intramolecular ring-closure of (cycloheptenylmethyl)benzenamine (3). The mechanisms of the reactions are also discussed.

To investigate the influence of C-doping on the electrostatic structure properties in the frame work of density functional theory (DFT), we considered beryllium monoxide nanotubes (BeONTs), consisting of 60 Be and 60 O atoms. Full geometry optimizations are performed for all structures, i.e., all atoms are allowed to relax. Afterwards, the chemical shielding (CS) tensors are calculated for Be-9, O-17 and C-13 nuclei in the C-doped forms and also pristine models of the (10, 0) zigzag and (5, 5) armchair BeONTs. Formation energies indicate that C-doping of Be atom (CBe form) could be more favorable than C-doping of O atom (CO form) in both zigzag and armchair BeONTs. Gap energies and dipole moments detected the effects of dopant in the (5, 5) armchair models; however, those parameters did not indicate any significant changes in the C-doped (10, 0) zigzag BeONT models. The results show that the CS values for the Be and O atoms-contributed to the Be-C bonds or those atoms close to the C-doped region-in the CO form of BeONTs (zigzag and armchair) are changed. The same values only for the O atoms-contributed to the O-C bonds- in the CBe form of BeONTs (zigzag and armchair) are changed.

Two aluminosilicates were prepared under hydrothermal conditions. Silica, sodium aluminate, sodium sulfide and sulfur were used as raw materials. Starting with similar reacting mixtures, analcime (zeolite, Na(Si2Al)O6·H2O) and beidellite (clay, Na0.3Al2(Si, Al)4O10(OH)2·2H2O) were synthesized by varying pressures, 2 kbar and 1 kbar, respectively. Sulfur was present in both aluminosilicate surfaces, which confer to them particular adsorption properties. Additionally, water adsorption isotherms, under dynamical conditions, were obtained. Fractal dimension values and SEM micrographs reveal very different textural and morphological properties of the two prepared aluminosilicates

The synthesis of a new halogenide containing hexyltriethylene glycol chain functionalized with biotin is reported. The general possibility of this linker to use as the building block for biotinylated compounds syntheses is demonstrated. Two biotinylated esters with different properties for useful surface modification and as fluorescence probes for proteins marking were synthesized. The properties of mentioned compounds were investigated by using surface plazmon resonance ellypsometry and fluorescence spectroscopy.

The stability-indicating LC assay method was developed and validated for quantitative determination of cefoselis sulphate in the presence of degradation products formed during the forced degradation studies. An isocratic, RP-HPLC method was developed with C-18 (250 × 4.6 mm, 5 µm) column and 12 mM ammonium acetate-acetonitrile (95:5 V/V) as a mobile phase. The flow rate of the mobile phase was 1.0 mL min−1. Detection wavelength was 260 nm and temperature was 30°C. Cefoselis similarly to other cephalosporins was subjected to stress conditions of degradation in aqueous solutions including hydrolysis, oxidation, photolysis and thermal degradation. The developed method was validated with regard to linearity, accuracy, precision, selectivity and robustness. The method was applied successfully for identification and determination of cefoselis sulphate in pharmaceuticals and during kinetic studies.

A study using coagulation-flocculation and ultrafiltration (UF)methods for pulp and paper mills’ wastewater (WW)was carried out. The reduction efficiencies of turbidity and chemical oxygen demand (COD), the removal efficiency of total suspended solids (TSS) and absorbance at 254 nm were the main evaluating parameters. Using coagulation-flocculation, the efficiencies of alum and polyaluminum chloride (PACl)were studied, when used alone and when coupled with flocculant aids. During the coagulation-flocculation process, use of a single coagulant, the coagulant dosage, and the pH, play an important role in determining the coagulation efficiency. At the optimum PACl dosage of 840 mg L−1 and optimum pH of 9.0, turbidity reduction was found to be 94.5%. A combination of inorganic coagulant and flocculant, or polymer was applied, in which PACl was used coupled with the polyelectrolytes Organopol WPB20 and WPB40. PACl coupled with Organopol WPB20 by optimal pH 9 gave a 98.3% reduction of turbidity, 91.9% removal of TSS, and a 60.2% reduction in COD. Ultrafiltration trials were carried out on a pilot scale. A tubular module was used with ceramic membrane. This membrane is a multi-channel membrane with an active surface layer made of Al2O3 and ZrO2. Within the acidic range, the turbidity and TSS were removed at above 99%.

The 70SiO2-30CaO (wt.%) sol-gel glasses doped with 1, 3 and 5 NbF5 (wt.%) were prepared via polystep sol-gel route. The synthesized glasses were characterized by XRD, FTIR and SEM. Changes in 1.5 SBF solutions were measured by ICP-AES. XRD of the glasses stabilized at 700°C for 6 hours proved the presence of niocalite. FTIR was consistent with XRD data. The in vitro bioactivity study of all glasses prepared were carried out by soaking in 1.5 simulated body fluid (1.5 SBF) at 37°C for 6 and 12 days in static conditions. The FTIR reveals the formation of A-type and B-type carbonate containing hydroxyapatite (CO3HA) layer. Changes in 1.5 SBF solutions, after 6 days of soaking, show that the Ca concentration increased significantly, compared to the initial Ca content in the 1.5 SBF solution before in vitro test. After 12 days of immersion, the Ca concentration decreased, i.e., the formation of HA phase consumed Ca from 1.5 SBF solution. For all soaking times, the concentration of P is much lower than that the used 1.5 SBF. Based on these results we suggest that Ca and P play an active role in the future of the glasses. SEM depicts that the different morphology of hydroxyapatite can be formed as a function of soaking time.

A ligand system containing three carbamoylmethylphosphine oxide (CMPO) moieties attached to a tripodal platform with a central nitrogen atom has been synthesized for metal complexation and extraction from neutral and nitric acid solutions. Liquid-liquid extractions performed for Ln(III), both from neutral and acidic media, show excellent extraction properties which exceeded those for the known mono- and di-CMPO derivatives as well as the related tripodands. A considerable enhancement of the DLn values was observed in the presence of IL ([bmim][Tf2N]) in the organic phase towards lanthanide ions from 3M HNO3 solutions. The protonation of the central amine nitrogen atom of the ligand 1 in the acidic media provides also the effective extraction of the perrhenate anionic complexes. The europium complexes formed by mono- and tris-CMPO ligands in the solid state, as well as Eu(III) and Tb(III) complexes generated in solutions, possess intensive luminescence at 300K

Amperometric biosensors based on a gold planar electrode and on two types of nanocomposite electrodes consisting of multi-walled carbon nanotubes for the determination of L-malic acid designed for wine-makers were developed. The biosensors designed for wine-makers were constructed by immobilization of L-malate dehydrogenase and diaphorase within chitosan layers on the surface of the electrodes. The coenzyme NAD+ and the electrochemical mediator ferricyanide were present in the measuring solution. The current resulting from re-oxidation of produced ferrocyanide was measured at a working potential of +300 mV against an Ag/AgCl reference electrode. The biosensor based on a gold electrode showed linearity over the range 10–520 µM with a detection limit of 5.41 µM. Calibration curves for biosensors utilizing nanocomposites were obtained both with the linear range of 10 to 610 µM. The detection limits were 1.57 and 1.77 µM, respectively. The biosensors showed satisfactory operational stability (no loss of sensitivity after 30 consecutive measurements) and storage stability (90% of the initial sensitivity after one year of storage at room temperature). The results obtained from measurements of wine samples were in a good correlation with the standard HPLC method. Satisfactory biosensor sensitivity, specificity and stability allowed their successful commercialization.

A series of the complexes of the general formula [ClMo(CO)2(η 3-C3H5)(P-P)], [where (P-P) = (m-CH3C6H4)2P(CH2)2PPh2 (m-t-dppe); cis-Ph2PCH=CHPPh2 (cis-diphos); Ph2PCH2CH2AsPh2 (arsaphos); Ph2P(CH2)4PPh2 (dppb); (±)-1,2-C6H4(PMePh)2 (rac-diphos); (2R,3R)Ph2PC*H(Me)C*H(Me)PPh2 (+)-chiraphos; (R,R)-Me2C(O)2{C*HCH2PPh2}2 (-)-diop] were synthesised by the reaction of the precursor complex [ClMo(CO)2(η 3-C3H5)(CH3CN)2] with the corresponding ditertiary phosphine in acetone. The complexes were isolated as yellow to orange air-stable solids and characterised by elemental analyses, FTIR and multinuclear NMR [1H, 31P{1H}] spectroscopic techniques. The carbonyl force constant values were calculated by Cotton and Kraihanzel approximate secular equations using ν C≡O stretching frequencies observed in the FTIR and these were found to be 14.30–14.59 mdyne 0-A−1 and 0.23–0.70 mdyne Å−1 for K1 and Ki respectively. Spectroscopic evidences have confirmed cis-octahedral structures for the synthesized complexes.

In the present study, the effect of a conformational constraint introduced into the endomorphin-2 (Tyr-Pro-Phe-Phe-NH2, EM-2) structure was studied using computational analysis and radioligand binding assay. EM-2 was modified by connecting nitrogen atoms of both phenylalanine residues by a methylene bridge. The obtained analog did not bind to the µ- or δ-opioid receptors in the in vitro studies. The computational analysis of this analog showed twisted, type IV turns and the absence of canonical β-turns typical for the EM-2 structure, which can be explained by the lack of hydrogen bonds involving Phe4. Our results show that the introduction of chemical constraint in the EM-2 structure has a significant effect on opioid receptor affinity and in vitro bioactivity.

A theoretical study regarding the evaluation of the antioxidant character of three of the most wide-spread anthocyanidins (cyanidin, delphinidin and malvidin) was carried out at ab initio level. Different parameters (bond dissociation enthalpy, ionization potential, proton affinity, and electron transfer enthalpy) were computed for each OH group of the compounds in order to predict their antioxidant capacity. Several molecular descriptors based on frontier molecular orbital theory (hardness, electrophilicity, frontier charge density) were also calculated, as well as the atomic charges corresponding to the O atoms of the hydroxyl groups.

Peroxynitrite (ONOOH/ONOO-) which is formed in vivo under oxidative stress is a strong oxidizing and nitrating agent. It has been reported that several flavonoids, including quercetin, inhibit the peroxynitrite-induced oxidation and/or nitration of several molecules tested; however, the mechanism of their protective action against peroxynitrite is not univocally resolved. The kinetics of the reaction of quercetin with peroxynitrite was studied by stopped-flow as well as by conventional spectrophotometry under acidic, neutral and alkaline pH. The obtained results show that the protective mechanism of quercetin against peroxynitrite toxicity cannot be explained by direct scavenging of peroxynitrite. We propose that quercetin acts via scavenging intermediate radical products of peroxynitrite decomposition (it is an excellent scavenger of ·NO2) and/or via reduction of target radicals formed in the reaction with peroxynitrite.

A fuzzy model was designed to predict changes in surface tension and maximum absorbance due to self-assembly in a DMF solution of poly{1,1′-ferrocene-diamide-[1,3-bis(propylene) tetramethyl-disiloxane} as a function of temperature and concentration. The building of fuzzy rule-based inference systems appears as a grey-box because it allows interpretation of the knowledge contained in the model as well as its improvement with a-priori knowledge. The method provides accurate results and increases the efficiency of utilizing the available information in the model. Small mean squared errors (0.0064 for absorbance and 0.79 for surface tension) and strong correlations between experiment and simulated results (0.93 and 0.97, respectively) were found during model validation. The results showed that it is feasible to apply a Mamdani fuzzy inference system to the estimation of optical and surface properties of a ferrocenylsiloxane polyamide solution.

Synthesis and systematic investigation of the spectral-luminescent properties of “bis-flavonol” {1,4-bis-(3-hydroxy-4-oxo-4H-chromen-2-yl)-benzene} were performed. Hypothetical possibility for the double excited-state proton transfer reaction in bis-flavonol is discussed based on both quantum-chemical modeling and experimental data. Consecutive S1*-state transfer of the two protons of the title molecule is shown to be energetically unfavorable, however, still preserving a possibility for the concerted double proton transfer in the excited dienol form.

The lipophilicity values of selected acridinone (imidazoacridinone and triazoloacridinone) derivatives were measured by gradient reversed-phase high-performance liquid chromatography (RP-HPLC) using a C18 stationary phase with a water/acetonitrile mixture as a mobile phase. The retention times obtained served as input data and appropriate log kw values (i.e., the retention factor log kw extrapolated to 0% organic modifier) as an alternative to log P were calculated using the DryLab program. The relationships between the lipophilicity (log kw) and the chemical structure of the studied compounds, as well as correlation between experimentally determined lipophilicities (log kw) and log P data calculated using some commonly available software, are discussed.

For electrocatalytic determination of NADH, a graphite electrode modified with titania sol-gel/Meldola’s Blue/MWCNT/Nafion nanocomposite was proposed. The composition of the matrix film was optimised in terms of the content of carbon nanotubes and Nafion. Incorporation of a redox mediator, Meldola’s Blue, into the nanocomposite film enabled electrocatalytic determination of NADH at a low potential, −50 mV. For determination of ethanol, alcohol dehydrogenase (ADH) was immobilized into the matrix layer. Experimental conditions affecting the biosensor response were examined, including enzyme loading, temperature of measurement and pH of background electrolyte. Assessments of the analytical characteristics of the biosensor were performed with respect to sensitivity, limit of detection, operational stability, repeatability and reproducibility. The proposed biosensor showed electrocatalytic activity toward oxidation of ethanol with sensitivity of 2.24 µA L mmol−1, linear range from 0.05 to 1.1 mmol L−1, and limit of detection of 25 µmol L−1. The apparent Michaelis-Menten constant was 1.24 mmol L−1, indicating a high biological affinity of ADH/titania sol-gel/Meldola’s Blue/MWCNT/Nafion electrode for ethanol. The developed biosensor was tested in determinations of ethanol content in alcoholic beverages.

Photodegradation of quetiapine under UVC irradiation in methanol solution was investigated and structural elucidation of its photodegradation products was performed with the use of the reversed phase UHPLC system coupled with accurate mass hybrid ESI-Q-TOF mass spectrometer. During one run all essential data for the determination of photodegradation kinetics and for the structural elucidation of the products was collected with the use of auto MS/MS mode. Five degradation products were found and their masses and formulas were obtained with high accuracy (0.26–5.02 ppm). For all the analyzed compounds, MS/MS fragmentation spectra were also obtained allowing structural elucidation of the unknown degradation products and indicating photodegradation pathways of quetiapine. The main photodegradation product was identified as 2-[2-[4-(5-oxidodibenzo[b,f][1,4]thiazepin-11-yl)-1-piperazinyl]ethoxy]-ethanol and the photodegradation reaction yields the first-order kinetics with the rate constant k = 0.1094 h−1.

The formation of hydrogen bonds and the molecular dynamics for molecules (Z)-1-(2-hydroxy-5-methyl-3-nitrophenyl)ethanone oxime and (E)-2-hydroxy-5-methylacetophenone thiosemicarbazone, (E)-4-bromoacetophenone thiosemicarbazone have been investigated in solution using NMR. The results confirm the formation of different O-H…O type intramolecular hydrogen bonds in the oxime molecule. The rotational barrier energy and energy of intramolecular hydrogen bonds have been determined.

The multidimensional Conformational Potential Energy Hypersurface (PEHS) of cyclotrisarcosyl was comprehensively investigated at the DFT (B3LYP/6-31G(d), B3LYP/6-31G(d,p) and B3LYP/6-311++G(d,p)), levels of theory. The equilibrium structures, their relative stability, and the Transition State (TS) structures involved in the conformational interconversion pathways were analyzed. Aug-cc-pVTZ//B3LYP/6-311++G(d,p) and MP2/6-31G(d)//B3LYP/6-311++G(d,p) single point calculations predict a symmetric cis-cis-cis crown conformation as the energetically preferred form for this compound, which is in agreement with the experimental data. The conformational interconversion between the global minimum and the twist form requires 20.88 kcal mol-1 at the MP2/6-31G(d)//B3LYP/6-311++G(d,p) level of theory. Our results allow us to form a concise idea about the internal intricacies of the PEHSs of this cyclic tripeptide, describing the conformations as well as the conformational interconversion processes in this hypersurface. In addition, a comparative analysis between the conformational behaviors of cyclotrisarcosyl with that previously reported for cyclotriglycine was carried out

The reaction rate of the oxidative addition and CO insertion steps of methyl iodide with [Rh(PhCOCHCOPh)(CO)(P(OCH2)3CCH3)] are presented. Large negative experimental values for the activation entropy and results from a density functional theory computational chemistry study indicated trans addition of the CH3I to [Rh(PhCOCHCOPh)(CO)(P(OCH2)3CCH3)]. A study of the molecular orbitals gives insight into the flow of electrons during the oxidative addition reaction. CO insertion leads to a square pyramidal [Rh(PhCOCHCOPh)(P(OCH2)3CCH3)(COCH3)(I)] acyl product with the COCH3 moiety in the apical position. The strong electron donation of the P(OCH2)3CCH3 ligand accelerates the oxidation addition step of methyl iodide to [Rh(PhCOCHCOPh)(CO)(P(OCH2)3CCH3)] by ca. 265 times faster (at 35°C) than that of the Monsanto catalyst, but inhibits the CO insertion step.

The present work reports the critical comparison about the employment of three different supporting electrolytes (0.1 mol L−1 HClO4, 0.01 mol L−1 EDTA-Na2 + 0.06 mol L−1 NaCl + 2.0 mol L−1 HClO4 and 0.1 mol L−1 KSCN + 0.001 mol L−1 HClO4) and their instrumental and chemical optimisation for the simultaneous voltammetric determination of total mercury(II) and copper(II) in sediments and sea water at gold electrode, especially discussing the reciprocal interference problems. The differential pulse anodic stripping voltammetric (DPASV) measurements were carried out using a conventional three-electrode cell: a gold electrode (GE) as working electrode, a platinum wire and an Ag‖AgCl‖KClsat as auxiliary and reference electrodes, respectively. The analytical procedure was verified by the analysis of standard reference materials: Estuarine Sediment BCR-CRM 277, River Sediment BCR-CRM 320 and Mercury in Water NIST-SRM 1641d. Once set up on the standard reference materials, the analytical procedure was transferred and applied to sediments and sea waters sampled in a lagoon ecosystem connected with Adriatic Sea (Ravenna area, Italy).

The original version of the article was published in Cent. Eur. J. Chem. 9(6) (2011), pp 1019–1026. Unfortunately, the original version of this article contains mistakes in the body of Fig. 1. Here we display the corrected version of the Fig. 1.