The Thermal Stability of Ciprofloxacin Complexes with Magnesium(II), Zinc(II) and Cobalt(II)

The thermal behaviour of Mg(II), Zn(II) and Co(II) compounds of ciprofloxacin was studied by thermogravimetry (TG) and differential thermal analysis (DTA) in order to determine or to confirm some structural characteristics of substances. The complexes decompose in two steps: dehydration and pyrolytic decomposition of the anhydrous complexes to form metal oxide or metal fluoride. The dehydration process of one magnesium(II) compound takes place in two steps suggesting a marked difference in the bonding of water molecules. The different bonding mode of the ciprofloxacin molecules in both magnesium compounds leads to different residues of the thermal decompositions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Polypropylene composites filled by magnesium hydroxide coprecipitated with foreign ions

Rod‐like magnesium hydroxide (MH) particles were prepared via coprecipitation of the magnesium salt with foreign ions, such as copper(II), zinc(II), iron(III), and nickel(II). Flame retardant polypropylene (PP) composites were fabricated using these particles. The microstructure, flame retardation, mechanical properties, thermal behavior, and oxidation‐induced temperature were characterized. It was found that foreign ion compounds increased the flame retardancy. MH containing a zinc compound presented a similar performance as that of neat MH. The presence of a copper compound decreased the thermal behavior and mechanical properties of the flame retardant composite, while iron and nickel compounds brought some improvements. In addition, the thermal degradation mechanisms of the flame retardant composites were investigated by Fourier transform infrared (FTIR) spectroscopy at different temperatures. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and characterization of soluble porphyrazines bearing octakis 2-anthraquinonylmethylthio substituents

By cyclotetramerization of 1,2-bis(2-anthraquinonylmethylthio)maleonitrile in the presence of magnesium butanolate, magnesium porphyrazinate carrying eight (2-anthraquinonylmethylthio) functional groups on peripheral positions has been synthesized. The metal-free derivative was obtained by treatment with tri?uoroacetic acid; reaction of this product with copper(II) acetate, zinc(II) acetate, and cobalt(II) acetate led to the metal porphyrazinates [M?=?Cu(II), Zn(II), and Co(II)]. These new compounds have been characterized by elemental analysis, together with FT-IR, ¹H-NMR, ¹³C-NMR, UV-Vis, and mass spectral data.     

Synthesis and characterization of octakis-(9-anthracenylmethylthio) substituted novel porphyrazines

A magnesium porphyrazinate carrying eight (9-anthracenyl) units on the periphery through flexible methylthio-bridges has been synthesized by cyclotetramerization of 3,4-(9-anthracenylmethylthio) pyrroline-2,5-diimine in the presence of magnesium butanolate. The metal-free derivative was obtained by treatment with trifluoroacetic acid and further reaction of this product with copper(II) acetate, zinc(II) acetate, and cobalt(II) acetate led to the metal porphyrazinates (M = Cu, Zn, Co). These novel compounds were characterized by elemental analysis, together with FT-IR, ¹H-NMR, UV–Vis, and mass spectral data.     

Selenophilic reaction of organolithium and magnesium reagents with phosphinoselenoic chlorides

The reaction of phosphinoselenoic chlorides 1 with various organolithium and magnesium reagents was studied. Sequential reaction of phosphinoselenoic chlorides 1 with organolithium and magnesium reagents and elemental selenium gave two types of products, phosphine selenides 2 and phosphinodiselenoic acid esters 3 . The esters 3 appeared to be formed via the selenophilic reaction of organolithium and magnesium reagents with the chlorides 1 . Molecular orbital calculations were carried out for model compounds H₂P(E)Cl (E = O, S and Se) to determine their electronic structures. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:185–191, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20091     

Catalytic reduction of pralidoxime in pharmaceuticals by macrocyclic Ni(II) compounds derived from orthophthalaldehyde

Efficient catalytic method for the reduction of pralidoxime to its amine derivative by macrocyclic Ni(II) compounds has been developed. Ten macrocyclic Schiff base Ni(II) compounds were synthesized via non-template synthesis by treating the corresponding macrocycles with nickel chloride in 1:1 ratio. The resulting compounds were characterized by elemental, IR, (1)H NMR, (13)C NMR, mass, electronic spectra, conductance, magnetic, thermal studies and their structures have been proposed. These compounds were used as catalysts for the reduction of pralidoxime to its amino derivative. The reduced pralidoxime was also characterized by spectral analysis and catalytic cycle has been established. The reduced product was determined spectrophotometrically by treating with ninhydrin reagent and the percent yields were found to be in the range of 75.12-82.36%.     

Vinylmetalloids : I. Coupling reactions of group IV metalloidal halides with magnesium in tetrahydrofuran

The reaction of vinyl bromide with a mixture of magnesium and either dichlorodimethylsilane or dichlorodiethylgermane in tetrahydrofuran was found to give the corresponding coupled products: 1,1,2,2-tetramethyl-1,2-divinyldisilane (II) and 1,1,2,2-tetraethyl-l,2-divinyldigermane (XI), respectively, in ca. 30% yield. Other vinyl bromides also were investigated. The reaction of dichlorodimethylsilane with vinyl bromide/magnesium appears to proceed via chloro(dimethyl)vinylsilane (III) which was found to react directly with magnesium in THF to give II in 53% yield. It is shown that the reaction of a vinylsilyl halide with magnesium, if carried out in the presence of chlorotrimethylsilane or chlorotriethylgermane, leads to pentamethylvinyldisilane (VI) or triethyl(vinyldimethylsilyl)germane (V) in yields of 67 and 43%, respectively. However, the reaction of III and chlorotrimethylgermane with magnesium in THF gives a 40/60 mixture of trimethyl(vinyldimethylsilyl)germane (VII) and hexamethyldigermane (VIII). Under similar conditions, chlorotrimethylgermane was found to give VIII directly with magnesium in THF in 48% yield while chlorotriethylgermane is inert to Mg. These results are discussed in terms of the formation of metalloidalmagnesium bonds.     

Stable dimeric magnesium(I) compounds: from chemical landmarks to versatile reagents

The chemistry of the s-block metals is dominated by the +1 oxidation state for the Alkali metals (group 1) and the +2 oxidation state for the Alkaline Earth metals (group 2). In recent years, a series of stable dimeric magnesium(I) compounds has been prepared and their chemistry has started to develop. These complexes feature "deformable" Mg-Mg single bonds and are stabilised by sterically demanding and chelating anionic N-ligands that prevent their disproportionation. They have rapidly proven useful in organic and organometallic/inorganic reduction reactions as hydrocarbon soluble, stoichiometric, selective and safe reducing agents. The scope of this perspective focuses on stable molecular compounds of the general type LMgMgL and describes their synthesis, structures, theoretical and spectroscopic studies as well as their further chemistry. Also, comparisons are drawn with related complexes including magnesium(II) hydrides and dimeric zinc(I) compounds.     

Imino(phenoxide) compounds of magnesium: Synthesis,structural characterization,and polymerization studies

A plethora of magnesium compounds containing imino(phenoxide) (1–4) and bis(imino)phenoxide (5–10) ligand backbone have been synthesized via the reaction of diethyl magnesium with two equivalent of the corresponding ligand. These compounds were completely characterized by different spectroscopic techniques and elemental analyses. The monomeric nature of the magnesium complexes 3 , 5 , 6 , 9 , and 10 were further confirmed by single crystal X‐ray diffraction studies. The magnesium centers posses distorted trigonal bipyramidal geometry. The controlled hydrolysis compound Mg₇O₈ (C₂₂H₂₈NO₂)₆ ( 11 ) was adequately characterized using ¹H, ¹³C NMR, ESI‐MS, and the biscubane structure was further confirmed by single crystal X‐ray diffraction studies. The Mg₇O₈ core is deeply embedded with the ligand periphery. These compounds (1–10) were found to be active towards the bulk ring opening polymerization (ROP) of lactides, yielding polymers with high number average molecular weight (M_n) and controlled molecular weight distributions (MWDs). In addition, these compounds have been shown to be highly active toward the copolymerization of carbon dioxide with cyclohexene oxide and styrene oxide. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1474–1491     

Synthesis and spectroscopic characterization of asymmetric Schiff bases derived from 4′-formylbenzo-15-crown-5 containing recognition sites for alkali and transition metal guest cations

Asymmetric salen-type Schiff base ligands have been synthesized via a stepwise approach. In the first step, mono-Schiff base compounds were prepared by condensation of salicylaldehyde, 2-hydroxy-3-methoxybenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde and 2-hydroxy-1-naphthaldehyde with hydrazine hydrate. These compounds were then reacted with 4′-formylbenzo-15-crown-5 to prepare asymmetric ligands. ¹H-NMR spectra indicate that the mono- and asymmetric bis-Schiff base compounds exist in both (E) and (Z) isomeric forms in CDCl₃ solution. The asymmetric crown compounds form crystalline 1:1 (Na⁺:ligand) complexes with sodium perchlorate. Homo-metallic Ni(II) and Zn(II) complexes with 1:2 (metal:ligand) stoichiometries have also been synthesized. The results indicate that the Schiff base ligands coordinate through the azomethine nitrogen and phenolic oxygen.     

Co(II) and Ni(II) complexes with Schiff base ligands: Synthesis,characterization, and biological activity

The ligands, 1-acetylferrocenehydrazinecarboxamide (HL¹) and 1-acetylferrocenehydrazinecarbothioamide (HL²), and their Ni(II) and Co(II) complexes were synthesized. The properties of the synthesized compounds were determined by the elemental and spectroscopic analyses. Ni(II) and Co(II) acetates interact with the ligands at the molar ratios 1 : 1 and 1 : 2 to give coloured products. The complexes have octahedral geometry. The ligands are coordinated to Co(II) and Ni(II) centers via the azomethine nitrogen and thiolic sulfur /enolic oxygen atom. The ligands and their Co(II) and Ni(II) complexes were screened for antibacterial and antifungal activities. The Co(II) and Ni(II) complexes show enhanced inhibitory activity as compared to their parent ligands. The DNA cleavage activity of the Co(II) and Ni(II) complexes was determined by gel electrophoresis. It was shown that the complexes have better cleavage activity than the ligands. The antioxidant activity of the complexes was also evaluated and used to examine their scavenging ability on hydrogen peroxide.     

Chelating Polymers. III. Chelating Monomers and Polymers from s-Triazinyl Substituted Hydrazinoacetic Acids

The model chelating compounds β-[2,4-bis(dimethylamino)-s-triazin-6-yl] hydrazinoacetic acid, β-[2,4-bis(dimethylaniino)-s-triazind-yl] hydrazino-N, N-diacetic acid, 2,4-bis(dimethylamino)-s-triazin-6-yl-aminoacetic acid, and 2,4-bis(dimethylamino)-s-triazin-6-yl-iminodiacetic acid have been synthesized and characterized by composition analysis, infrared spectroscopy, and potentiometric titration data. The copper(II), nickel(II), cobalt(II), zinc(II), magnesium(II), and palladium(II) complexes of the first two model compounds, and the copper, nickel, cobalt, and zinc complexes of the third and fourth model compounds have been prepared. The infrared absorption spectra of the model compounds and their complexes were recorded for the range 3800 to 600 cm^?1, and the assignment of pertinent bands was made by comparison with reported infrared correlations. In those cases where applicable, shifts in the NH stretching vibration and carboxylate stretching vibration frequencies of the metal complexes were compared to those of the proper references and used as an indication of possible chelation effects in the metal complexes.

The aldehyde-reactable β-[2,4-diarnino-s-triazin-6-y1] hydrazinoacetic acid was also prepared and characterized; its polymers were prepared by the reaction of both the free ligand and its copper(II) complex with formaldehyde. Qualitative studies on the reaction of these polymers with metal ions and on the ease of metal ion elution from the polymers indicate that t h is a promising chelating polymer system.     

Synthesis of o,o′-dihydroxyazo compounds and their application to the determination of magnesium and calcium by flow injection analysis

Seven _o,o′-dihydroxyazo dyes were synthesized and examined as spectrophotometric reagents for magnesium and calcium. These reagents are highly sensitive for magnesium (? = 47 000) and calcium (? = 39 000 l mol^?1 cm^?1). Of the reagents synthesized, 2-(2-hydroxy-3,6-disulfo-1-naphthylazo)-5-(N,N-diethylamino)phenol was the best because of its ease of preparation and purification, and its stability in alkaline solution. This dye was applied in the determination of magnesium and calcium by flow injection analysis. The total concentration of magnesium (0.1–1.2 mg 1^?1) and calcium (0.4–4.0 mg 1^?1) was determined by masking iron(III), aluminium(III), copper(II), zinc(II), manganese(II) and cadmium(II) with 2,3-dimercapto-1-propanol (DMP) and triethanolamine (TEA). Magnesium was determined by masking calcium and the other metal ions with a ligand buffer containing barium(II)—EGTA, DMP and TEA. The amount of calcium was obtained as the difference between the two peak heights. Results for the determination of magnesium and calcium in potable water and serum are presented.     

The symmetrical porphyrazine with annulated six membered rings

Tetrakis(cyclohexylpyrazino)porphyrazinato magnesium(II) with annulated six membered rings has been prepared by two different methods. In Method A: cyclotetramerization of 2,3-dicyano-5,6-cyclohexanopyrazine (1) in the presence of Mg(OPr)₂ in n-propanol afforded the tetrakis(cyclohexylpyrazino)porphyrazinato magnesium(II) (2). In Method B: selenodiazole rings on the periphery of tetrakis(selenodiazole)porphyrazinato magnesium(II) were opened by the action of H₂S to yield the vicinal diamino functionalities. The ring closure of the vicinal diamino groups with 1,2-cyclohexanedione afforded the tetrakis(cyclohexylpyrazino) porphyrazinato magnesium(II) (2).     

Synthesis of Calcium and Magnesium Phosphates from Natural Carbonates and Study of Their Activity in Reactions with Lead(II) Ions

Chemical and thermal methods for obtaining calcium and magnesium phosphates from natural carbonate raw materials were studied. The activity of these compounds in uptake of lead(II) ions from solution was evaluated.     

Magnesium azaphthalocyanines: an emerging family of excellent red-emitting fluorophores

Magnesium(II), zinc(II), and metal-free phthalocyanines (Pcs) and azaphthalocyanines (AzaPcs) containing alkylsulfanyl, aryloxy, and dialkylamino peripheral substituents have been synthesized. The complexation of magnesium(II) by metal-free Pcs and AzaPcs has been studied in detail to determine the optimal reaction conditions necessary to ensure a complete conversion. Photophysical and photochemical measurements in tetrahydrofuran showed that magnesium(II) AzaPcs with aryloxy and alkylsulfanyl substituents have excellent fluorescent properties (Φ(F) up to 0.73) and that the corresponding zinc(II) Pcs are efficient singlet oxygen producers (Φ(Δ) up to 0.68). The presence of dialkylamino substituents causes intramolecular charge transfer within the molecule that competes with fluorescence and singlet oxygen formation. Alkylsulfanyl MgAzaPc and ZnAzaPc were the most photostable compounds among the series of studied derivatives. In addition, high molar absorption coefficients (ε ～ 300,000 M(-1) cm(-1)), absorption (λ(max) ～ 650 nm), and emission (λ(em) ～ 660 nm, high Φ(F)) in the red region suggest that these molecules are potential fluorescent probes that are superior to the commercial red cyanine dye Cy5. MgAzaPc, when incorporated into lipidic bilayers of liposomes, maintains excellent fluorescence properties (Φ(F) = 0.64). Water-soluble MgAzaPc with quaternary ammonium peripheral substituents retained a high fluorescence quantum yield even in water (Φ(F) = 0.25). The described properties show that magnesium(II) AzaPcs are excellent red-emitting fluorophores with potential applications as fluorescent probes in sensing or in vitro imaging applications.     

Synthesis,characterization, corrosion inhibition of mild steel in HCl (0.5 N) solution and solid‐state electrical conductivity of new Co(II), Ni(II), Cu(II) and Zn(II) complexes

This work consists of a study of the corrosion‐inhibiting and semiconducting properties of new binuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes with a Schiff base, H₂L, obtained from the 2:1 M condensation of salicylaldehyde and o‐dianisidine, respectively. Elemental, spectral and thermal analyses were used to characterize these complexes. The magnetic susceptibilities of these complexes were also determined. Weight loss, potentiodynamic polarization and scanning optical microscopy were the techniques used to investigate the efficiency of these new compounds as corrosion inhibitors. The antibacterial activity of the compounds was measured against sulfate‐reducing bacteria. It was found that inhibition occurs via the chemisorption of metal complexes on the steel surface. This absorption obeys the Langmuir adsorption isotherm model.     

Synthesis of a Dimeric Magnesium(I) Compound by an MgI/MgII Redox Reaction

The synthesis of dimeric magnesium(I) compounds of the general type RMgMgR (R=monoanionic substituent) is still a challenging synthetic task and limited to few examples with sterically demanding ligands with delocalized CN‐frameworks that all have been accessed by Na or K metal reduction of magnesium(II) halide precursors. Here we report on the synthesis of a novel diiminophosphinato magnesium(I) compound that has been synthesized by a facile redox reaction using a known magnesium(I) complex. The synthetic strategy may be applicable to other ligand systems and can help expand the class of low oxidation state magnesium complexes even if reductions with Na or K are unsuccessful. The new dimeric magnesium(I) complex has been structurally characterized and undergoes a C? C coupling reaction with tert‐butylisocyanate.     

Sulfanyl Porphyrazines with Morpholinylethyl Periphery—Synthesis,Electrochemistry, and Photocatalytic Studies after Deposition on Titanium(IV) Oxide P25 Nanoparticles

The syntheses, spectral UV–Vis, NMR, and electrochemical as well as photocatalytic properties of novel magnesium(II) and zinc(II) symmetrical sulfanyl porphyrazines with 2-(morpholin-4-yl)ethylsulfanyl peripheral substituents are presented. Both porphyrazine derivatives were synthesized in cyclotetramerization reactions and subsequently embedded on the surface of commercially available P25 titanium(IV) oxide nanoparticles. The obtained macrocyclic compounds were broadly characterized by ESI MS spectrometry, 1D and 2D NMR techniques, UV–Vis spectroscopy, and subjected to electrochemical studies. Both hybrid materials, consisting of porphyrazine derivatives embedded on the titanium(IV) oxide nanoparticles’ surface, were characterized in terms of particle size and distribution. Next, they were subjected to photocatalytic studies with 1,3-diphenylisobenzofuran, a known singlet oxygen quencher. The applicability of the obtained hybrid material consisting of titanium(IV) oxide P25 nanoparticles and magnesium(II) porphyrazine derivative was assessed in photocatalytic studies with selected active pharmaceutical ingredients, such as diclofenac sodium salt and ibuprofen.     

Fluorimetric determination of magnesium by ternary complex formation with pyridoxal nicotinylhydrazone and amines

The synthesis, characteristics and analytical applications of pyridoxal nicotinylhydrazone are described. This compound reacts with magnesium(II) in the presence of ammonia, ethylenediamine or pyridine, to produce a 1:1:1 Mg(II)—pyridoxal nicotinylhydrazone—amine fluorescent complex (λ_ex 395 nm, λ_em 480 nm). A fluorimetric method is proposed for the determination of magnesium(II) (20–100 ng ml^-1 in the solution measured); isobutanol is used to extract the complex, reducing the number of interferences.