A Copper(II) Ion‐Selective Potentiometric Sensor Based on N,N′,N″,N′′′‐Tetrakis(2‐pyridylmethyl)‐1,4,8,11‐tetraazacyclotetradecane in PVC Matrix

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

Synthese von Magnesium-bis[N,N′-bis(trimethylsilyl)benzamidinat] als Bis(THF)- und Benzonitril-Addukt

Synthesis of Magnesium Bis[N,N′ -bis(trimethylsilyl)benzamidinate] as both Bis(THF) and Benzonitrile Adduct Magnesium bis[bis(trimethylsilyl)amide] 1 , reacts with benzonitrile in toluene at room temperature to yield magnesium bis[N,N′-bis(trimethylsilyl)benzamidinate]-benzonitrile(1/1) 2 . Addition of THF leads to a quantitative substitution of the benzonitrile ligand by two THF molecules. The performance of the addition reaction in THF yields magnesium bis[N,N′-bis(trimethylsilyl)benzamidinate] · THF(1/2) 3 . The upper benzonitrile complex 2 , crystallizes in the orthorhombic space group Pbcn with {a = 1383.2(2); b = 2589.1(4); c = 1133.7(1) pm; Z = 4}. The magnesium atom is coordinated distorted trigonal-bipyramidal, where the benzonitrile ligand lies within the equatorial plane. The axial bound nitrogen atom of the benzamidinate substitution shows with a value of 213 pm a slightly longer bond distance to the metal center than the one in the equatorial plane (210 pm). The steric strain within the benzamidinate ligand leads to an elongation of the silicon atoms out of the 1,3-diazaallylic moiety under an enlargement of the C? N? Si angle to 131°.     

N,N,N′,N′,N″‐penta(methyl acrylate)diethylenetriamine: A novel ligand for atom transfer radical polymerization of methyl methacrylate

A novel ligand, N,N,N′,N′,N″‐penta (methyl acrylate) diethylenetriamine (MA₅‐DETA), was synthesized by the reaction of diethylenetriamine with methyl acrylate in almost quantitive yield. The polymerizations of methyl methacrylate with MA₅‐DETA as the ligand and α,α‐dichlorotoluene (DCT) and ethyl 2‐bromoisobutyrate (2‐EBiB) as the initiators, respectively, under different conditions were examined. The polymerization with CuCl/MA₅‐DETA/DCT was closely controlled in bulk and gave polymers with quite narrow molecular weight distributions (M_w/M_n's) of 1.16–1.29. The polymerization with the system CuBr/MA₅‐DETA/EBiB in bulk gave high activity. However, the system was not well controlled and gave the polymers with M_w/M_n = 1.35–1.53. The solution polymerization in anisole with CuBr/MA₅‐DETA/EBiB showed a better‐controlled nature. Moreover, the addition of CuBr₂ into the aforementioned system can further improve its controllability. The M_w/M_n's of the resulting polymers ranged from 1.11 to 1.21. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1963–1969, 2004     

Komplexe mit N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylendiamin (H4tben). Kristallstruktur von Ti(tben)

Complexes with N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylenediamine (H₄tben). Crystal Structure of Ti(tben) The complexes of N,N,N′,N′-tetrakis(2-hydroxybenzyl)-ethylenediamine with titanium(IV), vanadium(IV), manganese(IV), and tin(IV) were synthesized and characterized by mass spectrometry. The Mössbauer date were evaluated for the tin compound. The molecular structure of the titanium(IV) complex was determined by X-ray structural analysis, crystallographic data see “Inhaltsübersicht”.     

Reactions of N-(N′,N′,N″,N″-tetramethyl)guanidinyl-substituted Phosphines with Organoelement Chlorides involving Phosphorus,Sulfur, and Selenium; Formation of Stable Phosphino-, Thio-, and Selenophosphonium Salts

By reaction of N-(N′,N′,N″,N″-tetramethyl)guanidinyl-substituted phosphines with diorganochlorophosphines, organodichlorophosphines, p-tolylsulfenylchloride and phenylselenylchloride a variety of stable phosphonium chlorides with a P–E (E = P, S, Se) bond were obtained. In one case, performing this reaction in the presence of sodium tetraphenylborate led to the corresponding phosphonium tetraphenylborate. All compounds were characterised by multinuclear NMR and elemental analysis. The selenophosphonium chloride 4 a of the trihydrate was further characterised by a single crystal X-ray analysis. The P–Se bond is very long [193.0(3), 193.3(3) pm in two independent fomula units]. The water molecules and the chloride anions form hydrogen bonded layers.     

Complexes of diorganotin(IV) dihalides with N,N′-dimethyl-2, 2′-bisimidazole

Adducts of N, N′ -dimethyl-2, 2′-bisimidazole (DMBIm) with diethyl- and dibutyl-tin(IV) dihalides (Cl, Br) have been isolated and characterized. IR data for [SnR₂X₂(DMBIm)] compounds are in keeping with a six-coordinate tin atom with DMBIm acting as a bidentate ligand, whereas in [(SnR₂X₂)₂(DMBIm)] the tin is five-coordinate and DMBIm acts as a bridging ligand. Measurements of conductivity in acetonitrile show the adducts to behave as non-ionogens in this solvent. NMR data show them to undergo dissociation in CDCl₃.     

Strontium- und Barium-bis[N,N′ -bis(trimethylsilyl)benzamidinate] aus der Additionsreaktion der Erdalkalimetall-bis[bis(trimethylsilyl)amide] mit Benzonitril

Strontium and Barium Bis[N,N′-bis(trimethylsilyl)benzamidinates] from the Addition Reaction of the Alkaline Earth Metal Bis[bis(trimethylsilyl)amides] and Benzonitrile The reaction of strontium bis[bis trimethylsilyl)amide] with benzonitrile yields strontium bis[N,N′- bis(trimethylsilyl)benzamidinate] · 2THF, which crystallizes in the orthorhombic space group Pbcn (a = 1845.4(3); b = 131 1,3(2); c = 1838,(3) pm; Z = 4). During the similar reaction of barium bis[bis(trimethylsilyl)amide] with benzonitrile the benzonitrile adduct barium bis[N,N′-bis(trimethylsilyl)benzamidinate] · 2 THF · benzonitrile is formed. After the addition of diphenylacetylene to the strontium di(benzamidinate) in diglyme a clathrate of the composition strontium bis[N,N′-bis(trimethylsilyl)benzamidinate] · diglyme · diphenylacetylene could be isolated; the spectroscopic data as well as the X-ray structure (monoclinic, C2/c, a = 1492.2(2); b = 1539.1(2); c = 2337.8(3)pm; Z = 4) confirm the isolated appearance of the acetylene molecule without interaction to the metal center in solution and in the solid state, respectively.     

A Novel Al(III)‐Selective Electrochemical Sensor Based on N,N′‐Bis(salicylidene)‐1,2‐phenylenediamine Complexes

A polyvinylchloride membrane sensor based on N,N′‐bis(salecylidene)‐1,2‐phenylenediamine (salophen) as membrane carrier was prepared and investigated as a Al³⁺‐selective electrode. The sensor exhibits a Nernstian response toward Al(III) over a wide concentration range (8.0×10^?7–3.0×10^?2 M), with a detection limit of 6.0×10^?7 M. The potentiometric response of the sensor is independent of the pH of the test solution in the pH range 3.2–4.5. The electrode possesses advantages of very fast response and high selectivity for Al³⁺ in comparison with alkali, alkaline earth and some heavy metal ions. The sensor was used as an indicator electrode, in the potentiometric titration of aluminum ion and in determination of Al³⁺ contents in drug, water and waste water samples.     

Spectroscopic studies of new model compounds for poly[N,N′-bis(phenoxyphenyl)pyromellitimide]

New model compounds for poly[N,N′-bis(phenoxyphenyl)pyromellitimide] have been synthesized in order to investigate the formation of imine bonds which are proposed to form during the curing process and lead to crosslinking in the bulk polymer. Raman studies show that terminal amines can react with imide carbonyls during curing to form C?N bonds. The Raman band due to C?N appears at 1656 cm^?1 and the band due to C?O closest to the imine bond is observed at 1742 cm^?1. These results are in agreement with previously published results on vapor deposited polyimide films.     

Highly stable electrochromic polyamides based on N,N‐bis(4‐aminophenyl)‐N′,N′‐bis(4‐tert‐butylphenyl)‐1,4‐phenylenediamine

A new triphenylamine‐containing aromatic diamine monomer, N,N‐bis(4‐aminophenyl)‐N′,N′‐bis(4‐tert‐butylphenyl)‐1,4‐phenylenediamine, was synthesized by an established synthetic procedure from readily available reagents. A novel family of electroactive polyamides with di‐tert‐butyl‐substituted N,N,N′,N′‐tetraphenyl‐1,4‐phenylenediamine units were prepared via the phosphorylation polyamidation reactions of the newly synthesized diamine monomer with various aromatic or aliphatic dicarboxylic acids. All the polymers were amorphous with good solubility in many organic solvents, such as N‐methyl‐2‐pyrrolidinone (NMP) and N,N‐dimethylacetamide, and could be solution‐cast into tough and flexible polymer films. The polyamides derived from aromatic dicarboxylic acids had useful levels of thermal stability, with glass‐transition temperatures of 269–296 °C, 10% weight‐loss temperatures in excess of 544 °C, and char yields at 800 °C in nitrogen higher than 62%. The dilute solutions of these polyamides in NMP exhibited strong absorption bands centered at 316–342 nm and photoluminescence maxima around 362–465 nm in the violet‐blue region. The polyamides derived from aliphatic dicarboxylic acids were optically transparent in the visible region and fluoresced with a higher quantum yield compared with those derived from aromatic dicarboxylic acids. The hole‐transporting and electrochromic properties were examined by electrochemical and spectro‐electrochemical methods. Cyclic voltammograms of the polyamide films cast onto an indium‐tin oxide‐coated glass substrate exhibited two reversible oxidation redox couples at 0.57–0.60 V and 0.95–0.98 V versus Ag/AgCl in acetonitrile solution. The polyamide films revealed excellent elcterochemical and electrochromic stability, with a color change from a colorless or pale yellowish neutral form to green and blue oxidized forms at applied potentials ranging from 0.0 to 1.2 V. These anodically coloring polymeric materials showed interesting electrochromic properties, such as high coloration efficiency (CE = 216 cm²/C for the green coloring) and high contrast ratio of optical transmittance change (ΔT%) up to 64% at 424 nm and 59% at 983 nm for the green coloration, and 90% at 778 nm for the blue coloration. The electroactivity of the polymer remains intact even after cycling 500 times between its neutral and fully oxidized states. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2330–2343, 2009     

Die Kristallstruktur von Bis(N,N-Diethyl-N′-benzoylselenoureato)zink(II)

The Crystal Structure of Bis(N,N-Diethyl-N′-benzoylselenoureato)zinc(II) . Zn(C₁₂H₁₅N₂OSe)₂ crystallizes in the acentric orthorhombic space group Pca2₁. The cell parameters are a = 16.914(5), b = 13.492(4), c = 11.705(5) Å and Z = 4. The structure was solved with Patterson and direct methods and was refined to a final R-value of 7,05%. Zn^II is coordinated to two N,N-Diethyl-N′-benzoylselenoureato molecules, which are bidentately coordinated through their oxygen and selenium atoms to form a distorted tetrahedron. The Zn? Se bond lenghts are 2.394(3) and 2.369(4) Å, the Zn? O bond lengths are 1.971(11) and 1.974(12) Å.     

Synthesis and Properties of N,N′‐Bis(difuroxano [3,4‐b:3′,4′‐d]phenyl)oxalic Amide

N,N′‐Bis(difuroxano[3,4‐b:3′,4′‐d]phenyl)oxalic amide was synthesized via acylation, nitration, azidation, and pyrolysis‐denitrogenation from the starting materials of oxalyl chloride and 3,5‐dichloroaniline, under mild reaction conditions, with the yields of 81.0%, 82.0%, 86.0% and 81.7% respectively. The title compound and its precursors were characterized by ¹H NMR, IR, MS, and elemental analysis. The title compound has a density of 1.92 g·cm^?3 by a suspension method, a standard formation enthalpy of 979 kJ·mol^?1 calculated by Gaussian programs, a detonation velocity of 8.17 km·s^?1, and a detonation pressure of 31 GPa obtained by Kamlet Equation. The thermal decomposition reactions of the title compound at different heating rates were tested by differential scanning calorimetry (DSC). The kinetics parameters of the pyrolysis of the compound were calculated by Kissinger's method. The values of apparent activation energy (E_a) and pre‐exponential constant (A) were 226.7 kJ·mol^?1 and 10^23.17 s^?1 respectively. It was presupposed that N,N′‐bis(difuroxano[3,4‐b:3′,4′‐d]phenyl)oxalic amide would be a promising high energetic explosive with low sensitivity.     

Thermodynamic, crystallographic and solvent extraction properties of cobalt(II), nickel(II) and copper(II) complexes of ethylenediamine- N,N,N′,N′-tetraacetanilide

Complexes of ethylenediamine-N,N,N′,N′-tetraacetanilide (edtan, C₃₄H₃₆N₆O₁₄) with cobalt(II), nickel(II) and copper(II) in the solid state and in solution are reported for the first time. Thermodynamic data (stability constant, and derived Gibbs energy, enthalpy and entropy changes)for the 1 : 1 complexation of edtan with the metal ions at 298.15 K in water-saturated butan-1-ol gave the selectivity sequence log₁₀K_s; Ni²⁺, 4.56±0.02; Cu²⁺, 4.41±0.01; Co²⁺, 4.18±0.04 as found from microcalorimetric titration studies. The entropies suggested that the structure of the 1 : 1 complex with copper(II) contains fewer chelate rings than those for nickel(II) and cobalt(II) (δ_cS⁰ : Cu-21.4, Co 5.7, Ni 3.9 J mol⁻¹K⁻¹). Solid complexes of the metal ions with edtan and perchlorate as the counter anion were prepared. For each, a complex with a 1 : 1 metal: edtan stoichiometry with non-coordinated perchlorate was isolated. The X-ray structure of [Cu(edtan)(H₂O)][ClO₄]₂·1.5H₂O (1) revealed a six-coordinate Cu centre with edtan acting as pentadentate ligand (2N, 3O) with the coordination sphere completed by an oxygen atom from water. In striking contrast to the Cu complex, the Co centre in [Co(edtan)(H₂O)][ClO₄]₂·H₂O·0.5C₂H₅OH (2) is seven-coordinate with hexadentate edtan (2N, 4O) and one coordinated water molecule. There is thus an excellent confirmation of the results obtained from the microcalometric study in that edtan forms four chelate rings to Cu but five to Co in the solid state. The ability of the ligand to extract metal ions from water to the water-saturated butan-1-ol phase was assessed from distribution data as a function of the aqueous phase hydrogen ion concentration and of the ligand concentration in the organic phase. The data showed that Cu²⁺ is selectively extracted over a wide range of aqeous phase hydrogen ion concentrations.     

Synthesis of N,N′,X‐tridentate 2‐iminomethylpyrrole‐coordinated palladium(II) complexes via N─H bond activation of pyrrole moiety

The reaction of [Pd(CH₃CN)₂Cl₂] with N ‐functional group‐substituted 2‐iminomethylpyrrole‐based ligands, namely N ¹‐((1H‐pyrrol‐2‐yl)methylene)‐N ³,N ³‐dimethylpropane‐1,3‐diamine (L_A), N ¹‐((1H‐pyrrol‐2‐yl)methylene)‐N ³‐methyl‐N ³‐phenylpropane‐1,3‐diamine (L_B), N ‐((1H‐pyrrol‐2‐yl)methylene)‐3‐(methylthio)propan‐1‐amine (L_C) and N ‐((1H‐pyrrol‐2‐yl)methylene)‐3‐methoxypropan‐1‐amine (L_D), resulted in [L_n PdCl] (L_n  = L_A–L_D) complexes in high yield via N─H bond activation of pyrrole moiety without use of base. [L_n PdCl] existed as monomeric four‐coordinated complexes with slightly distorted square planar geometries around the palladium metal center. The ligands show N ,N ′,X ‐tridentate binding mode to the palladium metal center to give two fused ring metallacycles. [L_BPdCl] gave the highest activity (3.29 × 10⁵ g PMMA (mol Pd)⁻¹ h⁻¹) for a methyl methacrylate (MMA) polymerization in the presence of modified methylaluminoxane at 60 °C compared to the other Pd(II) analogues, and resulted in PMMA with higher molecular weight (M _w = 7.16 × 10⁵ g mol⁻¹) and narrower polydispersity index. Syndiotactic‐enriched PMMA resulted in all cases.     

Preparation and characterization of polyimide alternating copolymers incorporating N,N′-bis-(4-anilino)-1,2,4,5-benzene bis(dicarboximide)

N,N′-Di-(4-anilino)-1,2,4,5-benzene bis(dicarboximide) was prepared in a three-step synthesis and purified by heating the resulting solid to 200°C. Condensation of the diamino-diimide with several dianhydrides (BPDA, BTDA, and 6-FDA) yielded polyamic acid-imides that could be either thermally or chemically cured to the corresponding alternating copolyimides. Imidization of the polyamic acid-imide to the final polyimide was monitored by FTIR for samples coated on silicon wafers before being thermally cured. Polyimides prepared by chemical imidization were found by thermogravimetric analysis to be stable to temperatures of 600°C. © 1997 John Wiley & Sons, Inc.     

Synthesis of aromatic polyamide-imides from N,N′-bis(trimethylsilyl)-substituted aromatic diamines and 4-chloroformylphthalic anhydride

The polymerization of N,N′-bis(trimethylsilyl)-substituted aromatic diamines with 4-chloroformylphthalic anhydride in various solvents at a temperature range between 10 and 70°C afforded polyamide-amic acid trimethylsilyl esters having inherent viscosities of 0.8–1.4 dL/g. Transparent and flexible films of the silylated precursor polymers were obtained by casting directly from the polymer solutions. Desilylation of the silylated polymers with methanol resulted in the formation of the corresponding polyamide-amic acids. Subsequent thermal imidization of the silylated precursor polymers with the elimination of trimethylsilanol afforded yellow, transparent, and tough films of the aromatic polyamide-imides. The thermal conversion of the silylated precursor polymer to polyamide-imide proceeded almost as rapidly as that of the corresponding polyamide-amic acid prepared by a conventional method from the parent aromatic diamine and 4-chloroformylphthalic anhydride.     

Spectrophotometric Determination of Rhenium(IV) with Thiocyanate,TX-100 and N,N′-Diphenylbenzamidine

A spectrophotometric method to determine rhenium(IV) at trace level is based on the extraction of Re(IV)-SCN^? complex in sulphuric acid media with N,N′-diphenylbenzamidine(DPBA) in presence of a non-ionic surfactant triton X-100 (TX-100) in chloroform. The complex shows maximum absorbance at 435 nm with amolar absorptivity value of 4.24 × 10⁴ L mol^?1 cm^?1 at an acidity range 3.5-6.5 M H₂SO₄. The method followed Beer's Law for the system Re(IV)-SCN^?(TX-100)-DPBA upto 4.0 μg Re(IV) mL^?1. The detection limit of the method is 5 ppb. None of the tested foreign ions, except molybdenum(VI), interfere with the determination of rhenium. The interference due to molybdenum could effectively be removed by prior precipitation with oxine. The effect of various analytical parameters on the extraction of the metal are discussed.     

Poly(ethylene terephthalate) reinforced by N,N′‐diphenyl biphenyl‐3,3′,4,4′‐tetracarboxydiimide moieties

Starting with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and methyl aminobenzoate, we synthesized a novel rodlike imide‐containing monomer, N,N′‐bis[p‐(methoxy carbonyl) phenyl]‐biphenyl‐3,3′,4,4′‐tetracarboxydiimide (BMBI). The polycondensation of BMBI with dimethyl terephthalate and ethylene glycol yielded a series of copoly(ester imide)s based on the BMBI‐modified poly(ethylene terephthalate) (PET) backbone. Compared with PET, these BMBI‐modified polyesters had higher glass‐transition temperatures and higher stiffness and strength. In particular, the poly(ethylene terephthalate imide) PETI‐5, which contained 5 mol % of the imide moieties, had a glass‐transition temperature of 89.9 °C (11 °C higher than the glass‐transition temperature of PET), a tensile modulus of 869.4 MPa (20.2 % higher than that of PET), and a tensile strength of 80.8 MPa (38.8 % higher than that of PET). Therefore, a significant reinforcing effect was observed in these imide‐modified polyesters, and a new approach to higher property polyesters was suggested. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 852–863, 2002; DOI 10.1002/pola.10169     

THE EPR SPECTRA OF TETRADENTATE SCHIFF BASE COMPLEXES OF COPPER (II) I. N,N'-Bis-(acetylacetone) ethylenediimine and N,N'-Bis-(1,1,1-trifluoroacetylacetone) ethylenediimine

Abstract

The EPR spectrum of N, N'-bis-(acetylacetone)ethylenediimino Cu(II), [Cu-en(acac)₂], and N, N'-bis-(1,1,1-trifluoroacetylacetone)ethylenediimino-Cu(II), [Cu-en(tfacac)₂], have been studied in doped single crystals of the corresponding Ni(II) chelate. The parameters in the usual doublet spin-Hamiltonian are found to be: Cu[en(acac)₂], g_z =2.183 ± 0.003, g_x =2.047 ± 0.004, g_y =2.048 ± 0.004, A_z =204.8 × 10^?4cm^?1, A_x =31.5 × 10^?4cm^?1, A_y =27.1 × 10^?4 cm^?1, A_zN= 12.8 × 10^?4 cm^?1 and A_xN =A_yN =14.3 × 10^?4 cm^?1: Cu[en(tfacac)₂], g_z =2.192 ± 0.002, g_x =2.048 ± 0.004, g_y =2.046 ± 0.004, A_z =200.8 × 10^?4 cm^?1, A_x =31.1 × 10^?4 cm^?1, A_y =28.3 × 10^?4 cm^?1, A_zN =12.8 × 10^?4 cm^?1 and A_xN =A_yN =14.6 × 10^?4 cm^?1. These parameters are related to coefficients in the molecular orbitals of the complex. It is found that the α-bonding is quite covalent and there is significant in-plane σ-bonding. From the nitrogen hyperfine structure it is determined that the hybridization on the nitrogen is sp².     

Synthesis and characterization of soluble aromatic polyurea-amides from new N,N′--dimethyl-N,N′-bis(aminophenyl)ureas and aromatic dicarboxylic acid chlorides

Aromatic polyurea-amides having inherent viscosities of 0.36–0.67 dL/g were synthesized by the low temperature solution polycondensation of new N,N′-dimethyl-N,N′-bis(aminophenyl)ureas with various aromatic dicarboxylic acid chlorides. All the polymers were amorphous, and most of them were soluble in a variety of organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide (DMAc), m-cresol, and pyridine. Some of the polymers could be cast from the DMAc solutions into transparent and flexible films having good tensile properties. The glass transition temperatures of the polyurea-amides obtained from the bis(4-aminophenyl)-substituted ureas were 244–272°C. The temperatures of 10% weight loss under nitrogen of the polymers were in the range of 430 and 480°C. © 1995 John Wiley & Sons, Inc.