Quantitative analysis of cefixime via complexation with palladium(Ⅱ) in pharmaceutical formulations by spectrophotometry

An optimized and validated spectrophotometric method has been developed for the determination of cefixime in pharmaceutical formulations. The method is based on the complexa- tion reaction between cefixime and palladium ion in the presence of acidic buffer solution （pH 3） in ethanol-distilled water medium at room temperature. The complex absorbed maximally at 352 nm. Beer＇s law is obeyed in the working concentration range of 2.5-35 μg/mL with apparent molar absorptivity of 1.015×104 L/mol cm and Sandell＇s sensitivity of 0.001 μg/cm2/0.001 absorbance unit. The limits of detection and quantitation for the proposed method are 0.175 and 0.583μg/mL, respectively. The effect of common excipients used as additives has been studied in the determination of cefixime. The proposed method has been successfully applied for the determina- tion of cefixime in pharmaceutical formulations. The results obtained by the proposed method were statistically compared with the reference method using t and F values and found no significant difference between the two methods.

Do tensile and shear forces exerted on cells influence mechanotransduction through stored energy considerations?

All tissues in the body are subjected externally to gravity and internally by collagenfibril and cellular retractive forces that create stress and energy equilibrium required for homeostasis.Mechanotransduction involves mechanical work(force through a distance)and energy storage as kinetic and potential energy.This leads to changes in cell mitosis or apoptosis and the synthesis or loss of tissue components.It involves the application of energy directly to cells through integrin-mediated processes,cell-cell connections,stretching of the cell cytoplasm,and activation of the cell nucleus via yes-associated protein(YAP)and transcriptional coactivator with PDZ-motif(TAZ).These processes involve numerous complexes,intermediate molecules,and multiple pathways.Several pathways have been identified from research studies on vertebrate cell culture and from studies in invertebrates.These pathways involve mechanosensors and other molecules that activate the pathways.This review discusses the mitogen-activated protein kinase(MAPK)family,Hippo,Hedgehog,and Wingless-related integration site(WNT)/βcatenin signaling pathways.The mediators covered includeβcatenin,ion channels,growth factors,hormone receptors,members of the Ras superfamily,and components of the linker of nucleoskeleton and cytoskeleton(LINC)complex.However,the interrelationship among the different pathways remains to be clarified.Integrin-mediated mechanotransduction involves direct tensile loading and energy applied to the cell membrane via collagenfibril stretching.This energy is transferred between cells by stretching the cell-cell connections involving cadherins and the WNT/βcatenin pathway.These alterations induce changes in intracellular events in the cytoskeleton and nuclear skeleton caused by the release of YAP and TAZ.These coactivators then penetrate through the nuclear pores and influence nuclear cell function.Alteration in the balance of forces and energy applied to cells and tissues is hypothesized to shift the cell-extracellular matrix mechanical equilibrium by modifying mechanotransduction.The shift in equilibrium can lead to either tissue synthesis,genetic modifications,or promotefibrotic diseases,including epithelial cell-derived cancers,depending on the local metabolic conditions.

Synthesis and Spectroscopic Characterizations on the Complexation of Three Different Metal Ions Ba(Ⅱ),Ni(Ⅱ),and Ce(Ⅲ)with Atenolol Drug Chelate

Three types of metal ions barium(Ⅱ),nickel(Ⅱ)and cerium(Ⅲ)complexity of ATN drug have been prepared and characterized using molar conductance method,FT-IR,electronic,and 1H-NMR analysis measurements.The chemical and physical results for all atenolol complexes are agreement with the speculated structures.For the divalent(Ba&Ni)and trivalent(Ce)metal atenolol a molar ratio 1∶2 was established.Qualitative chemical analysis showed that for the divalent metal complexes,the chloride ions are not involved in the complexes,suggesting that all of these complexes,[Ba(ATN)2]·2 H2O and[Ni(ATN)2(H2O)2]·4 H2O are neutral.However,for the cerium(Ⅲ)complex,[Ce(ATN)2(NO3)]·3 H2O,the nitrate group is existed inside the coordination sphere.ATN make astable metal complexity with barium(Ⅱ),nickel(Ⅱ)and cerium(Ⅲ)ions.Electronic absorption analysis of Atenolol give two fundamental peaks at 225 nm and 274 nm refers to variation in transition electrons of ligand,UV spectral analysis of the three complexity obtained give asymmetric broad band in the range 200~400 nm,the reults are convenient with the suggestion of metal-nitrogen and metal-oxygen bonds.The infrared analysis data proved that ATN act as bidentate ligand through the N atom of the-NH group and O atom of the deprotonated alcoholic OH group.Nickel(Ⅱ)and cerium(Ⅲ)complexity make six-coordinate geometry,whereas the barium(Ⅱ)complex exhibit four-coordinate geometry.Ni(Ⅱ)-ATN complex has an effective magnetic moment equal 3.12 B.M,that is assigned to octahedral structure.The 1H-NMR spectral results of Ba(Ⅱ)-ATN complexity give strong signal at^4.00 ppm due to protons of-CH2 that influenced by low degree due to complexity.These results confirm the position of chelation through the N atom of the-NH group and O atom of the deprotonated alcoholic OH group.

Lithium ion conductivity of complex hydrides incorporating multiple closo–type complex anions

We report the lithium ionic conductivities of closo –type complex hydrides synthesized from various molar ratios of lithium borohydride(LiBH4) and decaborane(B10H14) as starting materials. The prepared closo –type complex hydrides comprised [B12H12]^2-, [B11H11]^2-, and [B10H10]^2- complex anions. In addition, increasing the LiBH4 content in the starting materials increased the amounts of [B11H11]^2- and [B10H10]^2-, leading to an improved ion conductivity of the prepared sample. The present study offers useful insights into strategies for controlling the complex anion composition in emerging solid electrolytes of closo-type complex hydrides at the molecular level, and improving their ionic conductivities.

Preparation and Characterization of Hydroxyiron-Montmorillonite Complexes

Hydroxy Fe ions react slowly with montmorillonite by intercalation into their interlayer space and adsorption on their surface to form various hydroxyiron montmorillonite complexes. Hydroxyiron montmorillonite complexes are assumed to have the ability to adsorb anions such as H 2PO - 4, HPO 2- 4, CrO 2- 4, CrO - 2, H 2AsO - 4, HAsO 2- 4 , AsO 3- 4 and F -, which may come from weathered rocks or waste industrial water, and result in concentration of P, Cr, As and F in soil. In this paper, hydroxy Fe ions including Fe(OH) 2+ , Fe(OH) + 2 and Fe 2(OH) 2+ 2 are prepared through hydrolysis of iron in acid solutions with different pH values. Corresponding hydroxyiron montmorillonite complexes are obtained by intercalation and adsorption of these hydroxy Fe ions into the interlayer space and on the surface of montmorillonite. The obtained hydroxyiron montmorillonite complexes are characterized with XRD and DTA, showing that they have similar basal space and thermal stability with Fe montmorillonite.

Thiocyanate Ion Selective Solid Contact Electrode Based on Mn Complex of N,N'-BIs-(4-Phenylazosalicylidene)-O-Phenylene Diamine Ionophore

A thiocyanate ion selective poly(aniline) solid contact electrode based on manganese complex of N,N’-bis-(4-phenylazosalicylidene)-o-phenylene diamine ionophore was successfully developed. The electrode exhibits a good linear response of 58.1 mV/decade (at 20?C ± 0.2?C, r2 = 0.998) with in the concentration range of 1 × 10–1.0 ~ 1 × 10–5.8 M thiocyanate solution. The composition of this electrode was: ionophore 0.040, polyvinylchloride 0.300, dibutylphthalate 0.660 (mass). This dibutylphthalate plasticizer provides the best response characteristics. The electrode shows good selectivity for thiocyanate ion in comparison with any other anions and is suitable for use with aqueous solutions of pH 4.0 ~ 6.0. The standard deviations of the measured emf difference were ±1.70 and ±2.01 mV for thiocyanate sample solutions of 1.0 × 10–2 M and 1.0 × 10–3 M, respectively. The stabilization time was less than 170 sec. and response time was less than 17 sec.

An intravenous clarithromycin lipid emulsion with a high drug loading, H-bonding and a hydrogen-bonded ion pair complex exhibiting excellent antibacterial activity

The aim of this study was to develop an intravenous clarithromycin lipid emulsion(CLE)with good stability and excellent antibacterial activity. The CLE was prepared by the thinfilm dispersed homogenization method. The interaction between clarithromycin(CLA) and cholesteryl hemisuccinate(CHEMS) was confirmed by DSC, FT-IR and^1H NMR analysis. The interfacial drug loading, thermal sterilization, freeze–thaw stability, and in vitro and in vivo antibacterial activity were investigated systematically. DSC, FT-IR and^1H NMR spectra showed that CHEMS(CLA: CHEMS, M ratio 1:2) could interact with CLA through H-bonding and a hydrogen-bonded ion pair. The CHEMS was found necessary to maintain the stability of CLE.Ultracentrifugation showed that almost 88% CLA could be loaded into the interfacial layer.The optimized CLE formulation could withstand autoclaving at 121 °C for 10 min and remain stable after three freeze–thaw cycles. The in vitro susceptibility test revealed that the CLA–CHEMS ion-pair and CLE have similar activity to the parent drug against many different bacterial strains. The in vivo antibacterial activity showed that the ED50 of intravenous CLE was markedly lower than that of CLA solution administrated orally. CLE exhibited pronounced antibacterial activity and might be a candidate for a new nanocarrier for CLA with potential advantages over the current commercial formulation.

Gas Phase Activation of Methane Molecule with Lead Benzene Dication Complex Ion, [Pb(Benzene)₂]²⁺

Motivated by the search for ways of a more efficient usage of the ubiquitous, and unexploited resources of methane, recent progress in the gas-phase activation of methane by metal dication complex ion is discussed. The gas phase theoretical and experimental analysis on [Pb(Benzene)2]2+ was conducted. The [Pb(Benzene)2]2+ complex ions were prepared using a combination of the pick-up technique and high energy electron impact, and then held in a cold ion trap. Excitation with tuneable UV radiation resulted in the formation of [Pb(Benzene)2(H2O)]2+, [Pb(Benzene)2(H2O)2]2+, [Pb(Benzene)]+, Pb+ and Benzene+ ions when the experimental results were analysed. The two optimised geometries of [Pb(Benzene)2]2+ namely the C2V eclipse and C2 staggered were observed. Methane activation of [Pb(Benzene)2]2+ complex ion yielded [Pb(Benzene)2(Me)]2+. [Pb(Benzene)2(H2O)(Me)2]2+,? [Pb(Benzene)2(H2O)(Me)]2+, [PbBenzene(Me)3]2+ and [Pb(Benzene)(Me)]2+. The PEC calculated binding energy of methane to lead benzene dication complex ion was approximately 25.45% higher than the value recorded on DFT calculation. This difference was due to the charge differences on the lead metal centre. While the actual calculated charge on the Pb metal in the optimised geometry was 1.68 the charge of +2 on the Pb metal was considered in the PEC calculation.

EARLY PALEOZOIC SUBDUCTION-RELATED ACCRETIONARY COMPLEX IN WESTERN KUNLUN

Previous studies on ophiolite and granite revealed that a paleo\|ocean which was referred to as “Proto\|Tethys" developed in north part of western Kunlun in Pt 3～Pz 1.The geotectonic unit in Kuda, western Kunlun is composed of early Paleozoic accretionary complexes and the metamorphic equivalents due to subduction of Proto\|Tethys: Along the Xinzang highway (from Yecheng, Xinjiang to Shiquanhe, Tibet), about 30km north of Kuda, a schistose granodiorite intrudes a thick unit of deformed mafic rocks; Non to weakly metamorphosed early Paleozoic fore\|arc turbidite exposed in Yixiekegou; A set of metamorphic rocks about 20km wide in Kuda which was thought of the Precambrian basement is a large\|scale ductile shear zone determined by detailed field observation and laboratory research; About 10km north of Kuda, there is an undeformed potassic granite batholith intrudes the shear zone.The shear zone mainly consists of parametamorphic rocks and orthometamorphte rocks. Moreover, it contains various kinds of oceanic materials of different origins including fragments of seamounts, oceanic reef limestone and dismembered ophiolite suite, such as dunite, peridotite, gabbro and anorthisite with high number up to 91. The dismembered ophiolite suite may probably represents a remnant oceanic crust that related to the breakup of Rodinia. The parametamorphite rocks is composed of mica\|schist, quartzite and gamete\|mica schist,etc., of which protoliths are sedimentary rocks such as mudstone, sandstone, siliciclastic rocks and impure carbonates that most likely accumulated along the passive continental margin of pelagic sedimentary materials. The orthometamorphic rocks is composed of granitic gneiss and amphibolite,etc. The protoliths of amphibolite is oceanic island basalt of MORB basalt that was accretioned in accretionary complex. The accretionary wedge complex suffers intense ductile strain and metamorphism due to the subduction of Proto\|Tethys with the metamorphic grade reaching the greenschist facies to amphibolite facies. The 40 Ar/ 39 Ar age 451Ma of metamorphic homoblende in amphibolite is interpreted to closely date attainment of maximum metamorphic conditions representing the age of initial subduction at the latest, while the 40 Ar/ 39 Ar age 425Ma of biotite is interpreted as dating the post metamorphic cooling through temperatures required for intracrystalline retention of argon representing the cease of subduction. These data provide significant information on the timing of accretion and the age of the subducted Proto\|Tethys. The whole rock Sm\|Nd isochronal age of amphibolite is problematic 737Ma that maybe represent the rifting age of the Rodinia.

Treatment of nickel-ammonia complex ion-containing ammonia nitrogen wastewater

Air stripping was adopted to treat nickel ammonia complex ion-containing wastewater in order to remove nickel and ammonia simultaneously in one technological process.The relationship among pH,the concentration of nickel ammonia complex ion and total ammonia concentration was analyzed theoretically.Influence of pH value,water temperature,airflow rate and time on air stripping was studied in detail by static experiment in laboratory.The results show that at pH 11,temperature of 60℃and airflow rate of 0.12 m3/h,NH3 and Ni 2+concentrations remained in wastewater are less than 2 and 0.2 mg/L,respectively,after blowing for 75 min,which reaches the standard of the state discharge.When the tail gas is absorbed by 0.5 mol/L H2SO4 in order to avoid the secondary pollution,the absorption rate can achieve 70%.

Preparation and characterization of complexes of RE^(3+) with furfural modified water-soluble chitosan

Degraded chitosan, with highly water-solubility, was obtained by the oxidation of chitosan with H2O2, and then reacted with furrural. The final product coordinated with the rare earth ions （RE^3＋ = Sm^3＋, Eu^3＋）, which led to the formation of the complexes. The prepared complexes were characterized with Infrared Spectroscopy （IR）, Ultra Violet （UV）, fluorescence, X-Ray Diffraction （XRD）, and Thermogravimetric-Differential Scanning Calorimetry （TG-DSC） measurements.

Crystal Structure of the Addition Compound of N,N′-Bi(2-pyridylmethyl)-Oxamide and the Complex of Copper with 1,10-Phenanthroline

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Identification of Complex Ions of Nb(V)in FLINAK-O^(2-)System by Infrared Spectra

The FT-IR spectra for K_2NbF_7-FLINAK-O^(2-) solution were measured and compared with the spectra of crystalline K_2NbF_7 and K_2NbOF_6.The results show that the niobium fluoro-complex and/or oxyfluoro-complex ions are presented in these solutions.NbF_7^(2-) complex ion is the predominant species in Nb(V)-FLINAK solution(not considering oxide impurity).The influence of O^(2-) on the oxyfluoro-complex ions shows that NbOF_6^(3-) as a stable monooxyfluoro-complex anion presented in FLINAK-O^(2-) systems and the number of NbOF_6^(3-) species are increased with increasing of O^(2-) when molar ratio of O^(2-)/Nb(V) is less than 1.

ION CONDUCTION IN COMPLEX OF ACRYLONITRILE-COPOLYMERIZED COMB POLYETHER WITH LITHIUM PERCHLORATE

Poly (oligoether methacrylate-co-acrylonitrile) s, P (MEOn- AN), with oligoether pendants of different lengths were synthesized and the ion conduction property of their Li-salt complexes was studied as the function of polymer structure. At proper copolymer composition, lithium concentration and pendant length, the ion conductivity reaches 7.0×10^(-5)S/cm at ambient temperature, together with improved mechanical strength. The ion transport in the polymer media is assisted by segmental relaxation, which is confirmed both by the consistency between ion conductivity and T_g and by the study of TSC.

Studies on Electrophilic Substitution of Quasi-Aromatic Metal Ion Complexes

The electrophilic substitution reaction occurring to the chelate ring of the complexes could be regarded as an indication of quasi-aromaticity of the ring systems, no catalyst was used and only triethylamine was employed, implying that the aroylating agents with different p-substituents are polarized enough to be effective electrophiles to attack the methine carbon of the electron-rich substrate 1. This property is probably the clue to polarization of the ligand electrons by the nickel( Ⅱ ) ion and to the participation of the nickel( Ⅱ ) in the π-bond systems of the two coordinated conjugated rings. The linearity relationship between vd-d maxima, E1/2OX(1) and σp are obtained, respectively. The electronic environment of central metal ion as well as the aromaticity of the ring system are affected by the electronic properties of the p-substituents. A comparison of the electrochemical results with each other showed .that when the electronegativity of the substituent was higher, the oxidation(Ni2+/Ni3+) becomes more difficult.

A Kinetic Study on Dismutation of Superoxide Ion by Macrocyclic Dioxotetramine-Copper(Ⅱ) Complex by Using Pulse Radiolysis

We studied the reaction kinetics of dismutation for superoxide ion by copper (Ⅱ) complex of macrocycllc dioxotetramine ligand 12- ( 4' - nitro )- benzyl-1,4,7,10- tetraazacy-clotridecane-11,13-dionato copper (Ⅱ) by using pulse radiolysis. The rate constants of dismutation kcat's were measured to be 1. 78×106 mor-1 . L.s-1(at pH 7. 0) and 1. 06×106 mol-1. L. s-1(at pH 7. 8). The reaction mechanism is similar to that catalyzed by super-oxide dismutase.

Determination of Boron Trifluoride in Boron Trifluoride Complex by Fluoride Ion Selective Electrode

A method was proposed to determine boron trifluoride in boron trifluoride complex using fluoride ion selective electrode(ISE). Hydroxide was chosen to mask aluminum for the determination of 0.01—0.1 mol/L of fluoride. The simulation indicated that the permissible aluminum masked at a certain p H value was limited and hardly related to F-concentration and boric acid. It is better to control p H value below 11.5 and the aluminum concentration within 0.025 mol/L to minimize the interference of hydroxide to the fluoride ISE. The decomposition conditions of boron trifluoride by aluminum chloride were investigated. It is found that the F-detection ratio will approach 1.0 if the Al/F molar ratio is 0.3—0.7 and aluminum concentration is no more than 0.02 mol/L when heated at 80 ℃ for 10 min. In one word, hydroxide is quite fit to mask aluminum for samples which contain high content of fluoride and aluminum and the BF3 content can be successfully determined by this method.

Novel Properties of Supramolecular Complexes Formed by Pairing Cationic Porphyrin and Anionic Metal-Oxo Cluster

MTBPyP (meso-tetrakis(4-N-benzylpyridyl)porphyrin, M=H-2, Zn) bearing positive charge has been shown to associate with SiW12O404- in water solution. The spectral evolution and Job's plots analyses reveal that the relatively stable aggregates contain equal numbers of MTBPyP4(+) and SiW12O404-.

Synthesis, characterization, and stability of iron (III) complex ions possessing phenanthroline-based ligands

It has previously been demonstrated that phenanthroline-based ligands used to make gold metallotherapuetics have the ability to exhibit cytotoxicity when not coordinated to the metal center. In an effort to help assess the mechanism by which these ligands may cause tumor cell death, iron binding and removal experiments have been considered. The close linkage between cell proliferation and intracellular iron concentrations suggest that iron deprivation strategies may be a mechanism involved in inhibiting tumor cell growth. With the creation of iron (III) phen complexes, the iron binding abilities of three polypyridal ligands [1,10-phenanthroline (phen), 2,9-dimethyl-1, 10-phenanthroline (methylphen), and 2,9-di-sec-butyl-1, 10-phenanthroline (sec-butylphen)] can be tested via a competition reaction with a known iron chelator. Therefore, iron (III) complexes possessing all three ligands were synthesized. Initial mass spectrometric and infrared absorption data indicate that iron (III) tetrachloride complex ions with protonated phen ligands (RphenH+) were formed: [phenH][FeCl4], [methylphenH][FeCl4], [sec-butylphenH][FeCl4]. UV-vis spectroscopy was used to monitor the stability of the complex ions, and it was found that the sec-butylpheniron complex was more stable than the phen and methylphen analogues. This was based on the observation that free ligand was observed immediately upon the addition of EDTA to the [phenH][FeCl4] and [methylphenH] [FeCl4] complex ions.

Some Hybrid Systems of Chiral Schiff Base Zn(II) Complexes and Photochromic Spiropyrans for Environmental Ion Sensing

This is a review article including our recent results and some previous photo functional hybrid system having potential applications for environmental ion sensing. We have prepared several new and known chiral Schiff base Zn(II) complexes and measured (and also calculated) absorption and fluorescence spectra for sole complexes. After assembling hybrid systems with 1,3,3-trime- thylindolino-6’-nitrobenzopyrylospiran (SP) in methanol solutions, we measured spectral changes before and after alternate irradiation of UV and visible light. Intensity of fluorescence spectra for pale yellow Zn(II) complexes (λem = 450 nm, λex = 270 and 360 nm) was quenched by colorless SP (λem = 533 nm, λex = 612 nm). After UV light irradiation to form purple merocyanine (MC), photoisomerization resulted in changes of the intensity of absorption spectra as well as fluorescence spectra. Thus the hybrid systems could successfully act as molecular logic circuit by input (excitation by light) and output (intensity of fluorescence peaks). Moreover, we investigated concentration dependence of doped Zn(II) and Cu(II) ions to confirm quenching of intensity of fluorescence peaks by Zn(II) and Cu(II) MC complexes for metal ion sensing in solutions.