On the Electroanalytical Detection of Zn Ions by a Novel Schiff Base Ligand-SPCE Sensor.

A novel bidentate Schiff base (L) is here proposed for the detection of Zn ions in water. The structure of the synthesized Schiff base L was characterized by FT-IR, 1H NMR and 13C NMR. Optical characteristics were addressed by UV-Visible spectroscopy and Photoluminescence (PL) measurements. PL demonstrated that L displays a "turn-off" type fluorescence quenching in the presence of Zn2+ ion in aqueous solution, indicating its ability to preferentially coordinate this ion. Based on these findings, an L-M (where M is a suitable membrane) modified screen-printed carbon electrode (SPCE) was developed to evaluate the electrochemical behavior of the Schiff base (L) with the final objective of undertaking the electroanalytical determination of Zn ions in water. Using various electrochemical techniques, the modified L-M/SPCE sensor demonstrates high sensitivity and selectivity to Zn ions over some common interferents ions, such as Ca2+, Mg2+, K+, Ni++ and Cd++. The potentiometric response of the L-M/SPCE sensor to Zn ions was found to be linear over a relatively wide concentration range from 1 µM to 100 mM.

Some new nanostructure zinc complex: Synthesis, spectral analyses, crystal structure, Hirshfeld surface analyses, antimicrobial/anticancer, thermal behavior and usage as precursor for ZnO nanostructure.

In this work, a new tridentate ligand, its some novel zinc halide/pseudohalide complexes and their antimicrobial and cytotoxic effects of them are described. Characterization data of these compounds have been achieved via several physical and micro analytical techniques. As typical one, X-ray crystal structure analysis of zinc azide complex was run showing zinc center is penta-coordinated by three nitrogen atoms from Schiff base ligand and two terminal azide nitrogen atoms as a distorted square pyramidal geometry. Hirshfeld surfaces analysis clears the important role of interactions related to azide groups (NH⋯N and CH⋯N hydrogen bonds) in the stabilization of its supramolecular structure. According to data obtained from thermal analysis (TG/DTG/DTA), all complexes are decomposed at four or more thermal stages below 1000 °C. Moreover antimicrobial activities of the compounds were screened against some gram positive and gram negative bacteria. Furthermore anticancer activities of the complexes were studied against MDA-MB468 and k562 as two cancer cell lines. In final, three zinc complexes were also synthesized in nano scale by sonochemical method and one of them was utilized as the precursor for preparation of nanostructure ZnO confirmed by XRD pattern and SEM image.

Construction of new iodide ion-selective electrodes based on new ionophores: comparison of the effect of structures and additives on electrode response.

New iodide ion-selective electrodes based on bis(2-methyl-3-phenyl-propenylidene)1,2-propanediamine)mercury(II) bromide [Hg(BMPPMB)Br2], bis (5-bromo salicylaldehyde) ethylenediimine vanadyl(IV) [VO(5-Br Salen)], and bis(5-bromo salicylaldehyde) ethylenediimine uranyl(VI) [UO2(5-Br Salen)] carriers are described. The electrodes exhibited Nernstian slopes of -58.3 +/- 1.0, -58.5 +/- 1.4, and -59.0 +/- 1.2 mV/decade for Hg(BMPPMB)Br2, VO(5-Br Salen), and UO2(5-Br Salen) iodide ion concentration in the range of 1.0 x 10(-6)-0.1 M, with detection limits of about 0.6, 0.5, and 0.3 microM, respectively. The potentiometric responses of the electrodes were independent of pH over the range 1.7-10.6, 2.2-11.3, and 2.1-11.1, with satisfactory reproducibility. The electrodes had response times of < or =5 s and could be used for at least 84, 80, and 100 days for Hg(BMPPMB)Br2, VO(5-Br Salen), and UO2(5-Br Salen), respectively, without any considerable divergence in their potential responses.

Synthesis and spectroscopic studies of some cadmium(II) and mercury(II) complexes of an asymmetrical bidentate Schiff base ligand.

Synthesis and spectroscopic studies on four-coordinate complexes of cadmium(II) and mercury(II) halides with a new asymmetrical bidentate Schiff base ligand of N,N'-bis[alpha-methylcinamaldehydene]propane-1,2-diamine(L) are described. The ligand and its complexes were characterized by elemental analysis, molar conductance, UV-visible spectra, FT-IR spectra, MS, (1)H NMR and (13)C NMR spectra. The complexes are non-electrolytes in DMF. The electronic spectra of the complexes were recorded in DMF solution. (1)H and (13) C NMR spectra been studied in CDCl(3). The molar conductance as well as spectral properties indicated the complexes do not dissociate in DMF and retain their coordination. FT-IR and NMR spectra of the complexes exhibit downfield as well as upfield shifts of the free ligand resonances that show change in geometry during the coordination. The suggested structure of the complexes is pseudo-tetrahedral. Molecular structures of the complexes have been optimized by MM+ calculations that supported pseudo-tetrahedral geometry around the metal (II) ions.

{4,4'-Dimeth-oxy-2,2'-[2,2-dimethyl-propane-1,3-diylbis(nitrilo-methyl-idyne)]diphenolato}nickel(II).

In the title complex, [Ni(C(21)H(24)N(2)O(4))], the Ni(II) ion has a slightly distorted square-planar geometry, coordinated by the two N and two O atoms of a new tetra-dentate Schiff base ligand. The dihedral angle between the planes of the two NiNC(3)O chelate rings is 14.37 (12)°.

2,2'-[(E,E)-1,1'-(2,2-Dimethyl-propane-1,3-diyldinitrilo)diethyl-idyne]diphenol.

The title Schiff base, C(21)H(26)N(2)O(2), contains two intra-molecular O-H⋯N hydrogen bonds between the hydroxyl groups and the nearest imine N atoms, each leading to a six-membered ring. Weak C-H⋯O hydrogen bonds result in a ladder network running along the a axis. In addition, inter-molecular C-H⋯π inter-actions serve to stabilize the extended structure.

{N,N'-Bis[(E)-3-phenyl-prop-2-en-1-yl-idene]propane-1,3-diamine-κN,N']dichloridocobalt(II).

The Co(II) atom in the title monomeric Schiff base complex, [CoCl(2)(C(21)H(22)N(2))], is bonded to two Cl atoms and to two N atoms of the Schiff base ligand N,N'-bis-[(E)-3-phenyl-prop-2-en-1-yl-idene]propane-1,3-diamine in a distorted tetra-hedral geometry. The mol-ecule has an idealised mirror symmetry, but is not located on a crystallographic mirror plane.

Bis{µ-4,4'-dimeth-oxy-2,2'-[propane-1,2-diylbis(nitrilo-methyl-idyne)]diphenolato}bis-({4,4'-dimeth-oxy-2,2'-[propane-1,2-diylbis(nitrilo-methyl-idyne)]diphenol}manganese(III)) bis-(hexa-fluorido-phosphate).

In the title complex, [Mn(2)(C(19)H(20)N(2)O(4))(2)(C(19)H(22)N(2)O(4))(2)](PF(6))(2), the Mn(III) ion is coordinated by two O [Mn-O = 1.855 (2) and 1.887 (2) Å] and two N [Mn-N = 1.982 (3) and 1.977 (3) Å] atoms from the tetra-dentate Schiff base ligand and a coordinated axial ligand [Mn-O = 2.129 (2) Å]. The centrosymmetric dimer contains two Jahn-Teller-distorted Mn(III) ions, each in a nearly octa-hedral geometry, connected through two phenolate bridges from two ligands. There are two stereogenic centers. The methyl group and the H atom attached to the middle propane C atom are disordered over two positions with occupancy factors in the ratio 0.58:0.42. The crystal is therefore a mixture of two diasteroisomers, viz. RS/SR and RR/SS. In the axial ligand, the two benzene rings form a dihedral angle of 56.97 (5)° and the dihedral angle between the two MnNC(3)O chelate rings is 2.98 (12)°

Design a sensitive optical thin film sensor based on incorporation of isonicotinohydrazide derivative in sol-gel matrix for determination of trace amounts of copper (II) in fruit juice: Effect of sonication time on immobilization approach.

A new selective and sensitive optical sensor based on the incorporation of new synthesized N'-(2-hydroxy-5-iodobenzylidene) isonicotinohydrazide (HIBIN) as an effective reagent into the nanoporous of a transparent glass like material through the sol-gel process was developed which was suitable for the determination of copper (II) ions in aqueous solutions. The thin film sensors were constructed by spin-coating of prepared sol onto glass plate and their surface morphology were studied by field emission scanning electron microscopy (FE-SEM) and atomic force microscope (AFM) technique. Influence of sonication time on immobilization of HIBIN into silica matrix was investigated through calculation of leaching percentage. The Results shown that sonication time of 35 min is suitable to give more stable thin films without fluctuation in sensitivity and response time of presented sensor for a long period of time. The proposed optical sensor can be used for determination of copper (II) ions in the range of 9.1 × 10-8-1.12 × 10-5 mol L-1with a detection limit of 1.8 × 10-8 mol L-1. It also showed relative standard deviation 3.4 and 0.72% for reproducibility and repeatability respectively, along with a fast response time about of 2 min. The constructed optode is stable in wet conditions and could be stored for at least 6 weeks without observing any change in its sensitivity. The developed sensor was successfully applied to the determination of copper (II) in fruit juice and water samples which results were confirmed by atomic absorption spectrometry method.

Fast and highly efficient solid state oxidation of thiols.

A fast and efficient solid state method for the chemoselective room temperature oxidative coupling of thiols to afford their corresponding disulfides using inexpensive and readily available moist sodium periodate as the reagent is described. The reaction was applicable to a variety of thiols giving high yields after short reaction times. Comparison of yield/time ratios of this method with some of those reported in the literature shows the superiority of this reagent over others under these conditions.

Bis[N,N'-(2-chlorobenzylidene)ethylenediamine-kappa2N,N']copper(I) dichloridocuprate(I) acetonitrile solvate.

The 1:1 adduct of N,N'-bis(2-chlorobenzylidene)ethylenediamine (cb2en) with copper(I) chloride proves to be an ionic compound with Cu(I)-centred cations and anions, [Cu(C16H14Cl2N2)2][CuCl2] x CH3CN. In the cation, the Cu(I) atom has a flattened tetrahedral coordination geometry, with a small bite angle for the chelating ligands, which form a double-helical arrangement around the metal centre. The anion is almost linear, as expected. The packing of the cations involves intermolecular pi-pi interactions, which lead to columns of translationally related cations along the shortest unit-cell axis, with anions and solvent molecules in channels between them.

The effects of some operational parameters in photodegradation of benzylamine and aniline and their kinetics in aqueous suspension of TiO2 and Pt -loaded TiO2.

Photocatalytic degradation of benzylamine and aniline on TiO2, Pt-modified TiO2, ZnO and ZnS in aqueous solution has been investigated. The degradation of the compounds follows a pseudo-first-order kinetics according to Langmuir-Hinshelwood model. The degradation process of benzylamine and aniline was evaluated by ninhydrin spectrophotometric method using UV-visible spectrophotometer in lambda(max) = 538 and 525 nm, respectively. The results showed the order of Pt/TiO2 > TiO2 > ZnO > ZnS for photocatalytic activity. In addition increasing of the Pt-loading was found to enhance the degradation rate of the compounds up to the optimal amount of 5 wt. % onto the surface of TiO2 so that the rates of degradation were increased about two times. Rate constants for photodegradation of benzylamine and aniline were found to be 1.4 x 10(-3) min(-1) and 0.7 x 10(-3) min(-1) for TiO2 as photocatalyst, while 2.7 x 10(-3) min(-1) and 1.7 x 10(-3) min(-1) for (5 wt.%) Pt/TiO2 as photocatalyst. Running the reactions in various pH (5-11), indicated that the pH = 8 and 10 or Higher are the optimum pH for photocatalytic degradation of benzylamine and aniline respectively. The effects of some other parameters such as amount of photocatalyst, flux of oxygen and irradiation time were evaluated. Furthermore, the Langmuir-Hinshelwood rate constant k(r) and adsorption constant K(A) for the titled compounds are reported.

Sonochemical synthesis of a new cobalt(II) complex: Crystal structure, thermal behavior, Hirshfeld surface analysis and its usage as precursor for preparation of CoO/Co3O4 nanoparticles.

A bidentate Schiff base ligand and its nano-structured cobalt(II) complex were synthesized under ultrasound irradiation and then their structures were identified by physical and spectral techniques SEM and XRD techniques were used to confirm the nanostructure character of the complex. Single crystal X-ray diffraction analysis showed that the complex crystallizes in the triclinic system with space group of P1¯ and two crystallographically independent molecules participate in its asymmetric unit. In the structure of complex, cobalt center is four-coordinated by two iminic nitrogens of bidentate Schiff base ligand and two bromide anions in a distorted tetrahedral geometry. Crystal packing analysis well indicates that C-H⋯Br, C-H⋯π and π⋯π are the most intermolecular interactions. Moreover Hirshfeld surface analysis and 2D Fingerprint plots were applied for more investigation of intermolecular interactions. In addition, sonochemically prepared cobalt(II) bromide complex was subjected to calcination process under air atmosphere for preparation of cobalt oxide nanoparticles. The XRD pattern confirmed the simultaneous formation of CoO and Co3O4 nanoparticles.

Simultaneous removal of Cd(II), Ni(II), Pb(II) and Cu(II) ions via their complexation with HBANSA based on a combined ultrasound-assisted and cloud point adsorption method using CSG-BiPO4/FePO4 as novel adsorbent: FAAS detection and optimization process.

Ultrasound irradiation, cloud point and adsorption methods were coupled to develop a new technique for the simultaneous removal of Cd(II), Ni(II), Pb(II) and Cu(II) ions after their complexation with (E)-4-((2-hydroxybenzylidene) amino) naphthalene-1-sulfonic acid (HBANSA). In order to reduce cost and improve practicability of process, chitosan gel (CSG) composited with bismuth(III) phosphate/iron(III) phosphate nanoparticles (CSG-BiPO4/FePO4) were hydrothermally synthesized followed by their characterization using FE-SEM, EDS and XRD analysis. The operational parameters such as metal ions concentration, CSG-BiPO4/FePO4 mass, sonication time and temperature were investigated and optimized using central composite design (CCD). In addition, the possible significant correlation between these variables and removal efficiency was studied from which the maximum efficiencies were obtained at 5.57mg/L, 51.49°C, 0.018g and 10.73min corresponding to metal ions concentration, temperature, CSG-BiPO4/FePO4 and sonication time, respectively. Moreover, at these conditions, the removal percentages of the Cd(II), Ni(II), Pb(II) and Cu(II) ions were found to be 96.24, 93.73, 95.55 and 97.47, respectively. After applying various isotherms, the Langmuir isotherm model was found to be most appropriate model for describing and fitting the experimental equilibrium data and thus maximum mono-layer adsorption capacities of 8.61, 8.54, 8.65 and 8.62mgg-1 were obtained for Cd(II), Pb(II), Cu(II) and Ni(II) ions, respectively. The study of kinetics showed well applicability of pseudo second order kinetic model with maximum mass transfer rate in adsorption process.

Tungstate sulfuric acid (TSA)/KMnO4 as a novel heterogeneous system for rapid deoximation.

Neat chlorosulfonic acid reacts with anhydrous sodium tungstate to give tungstate sulfuric acid (TSA), a new dibasic inorganic solid acid in which two sulfuric acid molecules connect to a tungstate moiety via a covalent bond. A variety of oximes were oxidized to their parent carbonyl compounds under mild conditions with excellent yields in short times by a heterogeneous wet TSA/KMnO4 in dichloromethane system.

Photodegradation kinetics of some thiols and thiones in aqueous suspension of zinc oxide.

Photodegradation of several thiols and thiones including 2-pyrimidinethiol, thiazolidine-2-thione, imidazolidine-2-thione, 1,2,4- triazole 3-thiol and 2,5-dimercapto- 1,3,4-thiadiazole have been studied in aerated aqueous solution using zinc oxide under irradiation with 400W high pressure mercury lamp. Rate constants span the range from 2.44 x 10(-2) min x (-1) to 1.76 x 10(-1) min x (-1). The slower degradation rate of 2-imidazoline 2-thione could be related to oxidation potential of the corresponding ring. The Langmuir-Hinshelwood (L-H) rate constant k(r) and adsorption constant, (KA) for all five thiols and thiones are reported.

Synthesis and crystal structure of the dinuclear copper(II) Schiff base complex µ-hydroxido-µ-chlorido-bis{[bis(trans-2-nitrocinnamaldehyde)ethylenediamine]chloridocopper(II)} dichloromethane sesquisolvate.

Transition metal complexes of Schiff base ligands have been shown to have particular application in catalysis and magnetism. The chemistry of copper complexes is of interest owing to their importance in biological and industrial processes. The reaction of copper(I) chloride with the bidentate Schiff base N,N'-bis(trans-2-nitrocinnamaldehyde)ethylenediamine {Nca2en, systematic name: (1E,1'E,2E,2'E)-N,N'-(ethane-1,2-diyl)bis[3-(2-nitrophenyl)prop-2-en-1-imine]} in a 1:1 molar ratio in dichloromethane without exclusion of air or moisture resulted in the formation of the title complex µ-chlorido-µ-hydroxido-bis(chlorido{(1E,1'E,2E,2'E)-N,N'-(ethane-1,2-diyl)bis[3-(2-nitrophenyl)prop-2-en-1-imine]-κ(2)N,N'}copper(II)) dichloromethane sesquisolvate, [Cu2Cl3(OH)(C20H18N4O4)2]·1.5CH2Cl2. The dinuclear complex has a folded four-membered ring in an unsymmetrical Cu2OCl3 core in which the approximate trigonal bipyramidal coordination displays different angular distortions in the equatorial planes of the two Cu(II) atoms; the chloride bridge is asymmetric, but the hydroxide bridge is symmetric. The chelate rings of the two Nca2en ligands have different conformations, leading to a more marked bowing of one of the ligands compared with the other. This is the first reported dinuclear complex, and the first five-coordinate complex, of the Nca2en Schiff base ligand. Molecules of the dimer are associated in pairs by ring-stacking interactions supported by C-H...Cl interactions with solvent molecules; a further ring-stacking interaction exists between the two Schiff base ligands of each molecule.

Synthesis, characterization and crystal structures of the bidentate Schiff base N,N'-bis(2-nitrocinnamaldehyde)ethylenediamine and its complex with CuNCS and triphenylphosphane.

Reaction of copper(I) thiocyanate and triphenylphosphane with the bidentate Schiff base N,N'-bis(trans-2-nitrocinnamaldehyde)ethylenediamine {Nca2en, (1); systematic name (1E,1'E,2E,2'E)-N,N'-(ethane-1,2-diyl)bis[3-(2-nitrophenyl)prop-2-en-1-imine]}, C20H18N4O4, in a 1:1:1 molar ratio in acetonitrile resulted in the formation of the complex {(1E,1'E,2E,2'E)-N,N'-(ethane-1,2-diyl)bis[3-(2-nitrophenyl)prop-2-en-1-imine]-κ(2)N,N'}(thiocyanato-κN)(triphenylphosphane-κP)copper(I)], [Cu(NCS)(C20H18N4O4)(C18H15P)] or [Cu(NCS)(Nca2en)(PPh3)], (2). The Schiff base and copper(I) complex have been characterized by elemental analyses, IR, electronic and (1)H NMR spectroscopy, and X-ray crystallography [from synchrotron data for (1)]. The molecule of (1) lies on a crystallographic inversion centre, with a trans conformation for the ethylenediamine unit, and displays significant twists from coplanarity of its nitro group, aromatic ring, conjugated chain and especially ethylenediamine segments. It acts as a bidentate ligand coordinating via the imine N atoms to the Cu(I) atom in complex (2), in which the ethylenediamine unit necessarily adopts a somewhat flattened gauche conformation, resulting in a rather bowed shape overall for the ligand. The NCS(-) ligand is coordinated through its N atom. The geometry around the Cu(I) atom is distorted tetrahedral, with a small N-Cu-N bite angle of 81.56 (12)° and an enlarged opposite angle of 117.29 (9)° for SCN-Cu-P. Comparisons are made with the analogous Schiff base having no nitro substituents and with metal complexes of both ligands.

Photocatalytic mineralisation of aniline derivatives in aquatic systems using semiconductor oxides.

Photocatalytic degradation of aqueous solution of aniline derivatives such as ortho-nitroaniline (ONA), meta-nitroaniline (MNA), para-nitroaniline (PNA), 4-bromoaniline (4-BrA) and 2-chloroaniline (2-ClA) were carried out over ZnO or TiO2 (anatase and rutile) in a photocatalytic reactor. The observed results revealed that the order of photocatalytic activity for degradation of selected compound was ZnO > TiO2 (rutile) > TiO2 (anatase) with the ratio of the rate constants to the surface area of 3.2 x 10(-3), 1.9 x 10(-3) and 1.0 x 10(-3) respectively. The effect of some physical and chemical parameters such as amount of photocatalyst, pH, time of irradiation and solvent were studied. Degradation kinetic was according to Longmuir behaviour. Spectrophotometric methods and TOC analysis supported that aniline derivatives almost completely mineralized.

Some new nano-structure zinc(II) coordination compounds of an imidazolidine Schiff base: spectral, thermal, antimicrobial properties and DNA interaction.

Some novel nano-sized structure zinc complexes of a new Schiff base ligand entitled as (3-nitro-benzylidene)-{2-[2-(3-nitro-phenyl)-imidazolidine-1-yl]-ethyl}-amine(L) with general formula of ZnLX2 wherein X=Cl(-), Br(-), I(-), SCN(-) and N3(-) have been synthesized under ultrasonic conditions. The ligand and its complexes have been characterized by elemental analysis, molar conductance measurements, FT-IR, (1)H and (13)C NMR and UV-Visible spectroscopy. The resulting data from spectral investigation especially (1)H and (13)C NMR well confirmed formation of an imidazolidine ring in the ligand structure. Transmission electron microscopy (TEM) showed nano-size structures with average particle sizes of 21.80-78.10nm for the zinc(II) Schiff base complexes. The free Schiff base and its Zn(II) complexes have been screened in vitro both for antibacterial activity against some gram-positive and gram-negative bacteria and also for antifungal activity. The metal complexes were found to be more active than the free Schiff base ligand. The results showed that ZnL(N3)2 is the most effective inhibitor against Escherichia coli, Pseudomonas aereuguinosa, Staphylococcus aureus and Candida albicans while ZnLBr2 was found to be more effective against Bacillus subtillis than other compounds. Moreover, DNA cleavage potential of all compounds with plasmid DNA was investigated. The results showed that the ligand and ZnLCl2 complex cleave DNA more efficiently than others. In final, thermal analysis of ligand and its complexes revealed that they are decomposed via 2-3 thermal steps in the range of room temperature to 1000°C. Furthermore some activation kinetic parameters such as A, E(*), ΔH(*), ΔS(*) and ΔG(*) were calculated based on TG/DTA plots by use of coats - Redfern relation. Positive values of activation energy evaluated for the compounds confirmed the thermal stability of them. In addition to, the positive ΔH(*), and ΔG(*) values suggested endothermic character for the thermal decomposition steps.