Preparation and characterization of new photosensitive and optically active poly(amide-imide)s from N-trimellitylimido-L-amino acid and dibenzalacetone moiety in the main chain

Six new photosensitive and optically active poly(amide-imide)s 8a–8f with good inherent viscosities based on dibenzalacetone moiety were synthesized from the direct polycondensation reaction of N-Trimellitylimido-L-amino acids 3a–3f with 2,5-bis(4-aminobenzylidene)cyclopentanone 7 by two different methods such as direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone/triphenyl phosphite/calcium chloride/pyridine and direct polycondensation in a tosyl chloride/pyridine (py)/N,N-dimethylformamide system. Diamine 7 was synthesized by using a two-step reaction. At first 2,5-bis(4-nitrobenzylidene)cyclopentanone 6 was prepared from the reaction of two equimolars 4-nitrobenzaldehyde 5 and one equimolar cyclopentanone 4 and dinitro compound 6 was reduced by using Na2S. Also N-trimellitylimido-L-amino acids 3a–3f were synthesized by the condensation reaction of trimellitic anhydride 1 with two equimolars of various L-amino acids 2a–2f in an acetic acid solution. The polymerization reactions produced a series of photosensitive and optically active poly(amide-imide)s with high yield and good inherent viscosity. The resulted polymers were fully characterized by means of FTIR and ¹H-NMR spectroscopy, elemental analyses, inherent viscosity, specific rotation, solubility tests, UV-VIS spectroscopy, differential scanning calorimeter, thermogravimetric analysis, and derivative of thermogravimetric. These macromolecules exhibited maximum UV-VIS absorption at around 395 and 265 nm in a N,N-dimethylformamide solution.     

First MnIII complexes with tetradentate (N2O2) Schiff bases and tricyanomethanide: synthesis,crystal structure,and magnetic properties

The first Mn^III complexes with Schiff bases and tricyanomethanide-anion were synthesized: [Mn(salen)C(CN)₃(H₂O)] (1), [Mn(5-Brsalen)C(CN)₃(H₂O)] (2), [Mn(salpn)C(CN)₃(H₂O)] (3), [Mn(3-MeOsalen)C(CN)₃(H₂O)] (4), [Mn(5-Brsalen)(MeOH)(H₂O)][C(CN)₃] (5), and [Mn(3-MeOsalpn)(H₂O)₂][C(CN)₃] (6), where SalenH₂ is N,N′-bis(salicylidene)ethylenediamine, 5-BrsalenH₂ is N,N′-bis(5-bromosalicylidene)ethylenediamine, SalpnH₂ is N,N′-bis-(salicylidene)-1,3-diaminopropane, 3-MeOsalenH₂ is N,N′-bis(3-methoxysalicylidene)-ethylenediamine, 3-MeOsalpnH₂ — N,N′-bis(3-methoxysalicylidene)-1,3-diaminopropane. The tricyanomethanide anion in complexes 1–4 acts as a the terminal ligand, whereas in complexes 5 and 6 tricyanomethanide is not coordinated by Mn^III and acts as an out-of-sphere counterion. The structures of complexes 1–4 are characterized by the formation of dimers due to hydrogen bonds between the water molecules and oxygen atoms of the Schiff bases. The Mn...Mn distances inside the dimers are 4.69–5.41 Å. Complex 6 has a zigzag chain structure consisting of the [Mn(3-MeOsalpn)(H₂O)₂]⁺ cations bound by double bridging aqua ligands. The study of the magnetic properties of complexes 1, 3, 4, and 6 showed the existence of antiferromagnetic interactions between the Mn^III ions through the system of hydrogen bonds.     

Heat stable and organosoluble benzoxazole or benzothiazole-containing poly(imide-ester)s and poly(etherimide-ester)s: synthesis and characterization

Two series of poly(imide-ester)s (PIEs) and poly(ether-imide-ester)s (PEIEs), having benzoxazole or benzothiazole pendent groups, were conveniently prepared by the diphenylchlorophosphate-activated direct polyesterification of two bis(imide-carboxylic acid)s (1), such as 2-[3,5-bis(N-trimellitimidoyl)phenyl]benzoxazole (1 _O ) and 2-[3,5-bis(Ntrimellitimidoyl) phenyl]benzothiazole (1 _S ) and two bis(imide-ether-carboxylic acid)s (2), such as 2-[3,5-bis(4-trimellitimidophenoxy)-phenyl]benzoxazole (2 _O ), and 2-[3,5-bis(4-trimellitimidophenoxy)-phenyl]benzothiazole (2 _S ) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. The structures, solubilities and thermal properties of obtained polymers were investigated in detail. All of the resulting polymers were characterized by FTIR and ¹H-NMR spectroscopy and elemental analysis. All of the resulting polymers exhibited excellent solubility in common organic solvents, such as pyridine, tetrahydrofuran and m-cresol, as well as in polar organic solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide and dimethyl sulfoxide. The modified polymers were obtained in quantitative yields with inherent viscosities between 0.47 and 0.67 dl·g^?1. Experimental results indicated that all the polymers had glass transition temperature between 198 °C and 262 °C, the decomposition temperature at 10% weight loss between 398 °C and 531 °C under nitrogen.     

A multidentate ligand based on two triazole groups from “click chemistry” and its copper(II) and iron(II) complexes: synthesis,structure, and electrochemistry

A multidentate ligand, namely N,N-bis[[1-(phenylmethyl)-1H-1,2,3-triazol-4-yl]methyl]-2-pyridinemethaneamine (L), was synthesized through a click reaction of N,N-di-2-propyn-1-yl-2-pyridinemethanamine with benzyl azide in the presence of CuI catalyst. Treatment of L with CuCl₂ or Fe(NCS)₂ gave the complexes [CuLCl₂]·EtOH (1) and [FeL(NCS)₂]·MeCN (2). Single-crystal X-ray studies show that in 1, the Cu(II) center has slightly distorted square pyramidal geometry resulting from the coordination of one pyridinyl nitrogen atom, one tertiary amine nitrogen atom, one triazole nitrogen atom, and two chloride atoms; in 2, the Fe(II) center has distorted octahedral geometry, coordinated by six nitrogen atoms; two each from NCS^? groups and triazole rings, one from a pyridinyl ring, and one from tertiary amine nitrogen. In addition, complexes 1 and 2 were characterized by spectroscopic and electrochemical methods.     

Synthesis and characterization of novel calix[4]arene piperazine derivative for the extraction of transition metals and dichromate ions

This article displays the synthesis of N-(2-tosylato)ethylpiperazine (ii) and 5,11,17,23-tetra-tert-butyl-25,27-bis-(2-piprazinoethyl)-26,28-dihydroxycalix[4]arene (3). Compounds (ii) and 3 were characterized through elemental analysis, FT-IR, ¹H NMR and/or ¹³C NMR studies. The transition metal cations (Hg²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Cd²⁺) and dichromate anion were studied by liquid–liquid extraction experiment. The results showed that compound 3 has moderate but selective extraction ability for Hg²⁺ and dichromate anion. Comparison between extraction properties of compound 3 with previously reported 5,11,17,23-tetra-tert-butyl-25,27-bis(isoniazidylcarbonylmethoxy)-26,28-dihydroxy-calix[4]arene (4) and protonated pyridinium form of 4 (5) is also described.     

Synthesis,crystal structure,and electrochemical properties of Ni(II) and Cu(II) complexes with two unsymmetrical N2O2 Schiff base ligands

Nickel(II) and copper(II) complexes of two unsymmetrical tetradentate Schiff base ligands [Ni(Me-salabza)] (1), [Cu(Me-salabza)] (2) and [Ni(salabza)] (3), {H₂salabza = N,N′-bis[(salicylidene)-2-aminobenzylamine] and H₂Me-salabza = N,N′-bis[(methylsalicylidene)-2-aminobenzylamine]}, have been synthesized and characterized by elemental analysis and spectroscopic methods. The crystal structures of 2 and 3 complexes have been determined by single crystal X-ray diffraction. Both copper(II) and nickel(II) ions adopt a distorted square planar geometry in [Cu(Me-salabza)] and [Ni(salabza)] complexes. The cyclic voltammetric studies of these complexes in dichloromethane indicate the electronic effects of the methyl groups on redox potential.     

Syntheses and optoelectronic properties of four photochromic dithienylethenes

Four photochromic dithienylethene compounds, 1,2-bis(2-methyl-5-naphthalene-3-thienyl)perfluorocyclopentene 1a, 1,2-bis[2-methyl-5(p-fluorophenyl)-3-thienyl]perfluorocyclopentene 2a, 1,2-bis[2-methyl-5(p-ethoxyphenyl)-3-thienyl]perfluorocyclopentene 3a, and 1,2-bis[2-methyl-5(p-N,N-dimethylaminophenyl)-3-thienyl]perfluorocyclopentene 4a were synthesized, and their optoelectronic properties, such as photochromism in solution as well as in poly-methylmethacrylate (PMMA) amorphous films, fluorescences and electrochemical properties were investigated in detail. These dithienylethenes have shown good photochromic behavior both in solution and in PMMA amorphous film. All of them exhibited relatively strong fluorescence and gave a bathochromic shift upon increasing concentration in THF. The irreversible anodic oxidation of 1a, 2a and 4a was observed by performing cyclic voltammetry experiments.     

Syntheses and structural studies of hexa- and pentacoordinated Zn complexes derived from 2-(aminomethyl)benzimidazole and water

The complexes trans-bis[2-(aminomethyl)-1H-benzimidazole-κ ² N′,N″]diaquazinc(II) dichloride dihydrate 1 and trans-bis[2-(aminomethyl)-1H-benzimidazole-κ ² N′,N″]aquazinc(II) dichloride dihydrate 2 were synthesized selectively by the promotion of O–H···Cl hydrogen bond interactions. The hexacoordinated complex 1 was synthesized at pH 4.5. The dilution of 1 in deionized water produced the pentacoordinated complex 2. NMR and vibrational spectroscopies corroborated the presence of these compounds. Moreover, mass spectrometry and thermogravimetric (TGA) studies demonstrated that chloride ions and crystallization water molecules are essential for the stabilization of 1 but not for complex 2. X-ray diffraction crystallography studies indicated that the presence of two water molecules bonded to the Zn atom elongated all of the coordination bonds. The incidence of a network of hydrogen bond interactions compensates for the unstable hexacoordination. Natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) studies of the crystal structures of 1 and 2 were used to explain the nature of the coordination bonds and the complexes’ stability .     

Synthesis, characterization and aggregation behaviour of novel peripherally tetra-substituted octacationic water soluble metal-free and metallophthalocyanines

In this study, a new phthalonitrile derivative 3 bearing 1,3-bis[3(dimethylamino)phenoxy]propan-2-ol 1, metal-free phthalocyanine (Pc) 4, metallophthalocyanines (MPcs) 5–7 and their quaternized derivatives 4a–7a were synthesized. Metal-free Pc 4 was prepared by cyclotetramerization of phthalonitrile derivate 3 and MPcs 5–7 were synthesized by heating 3 with NiCl₂, CoCl₂ and CuCl₂ in n-pentanol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, respectively. Quaternization of the dimethylamino functionality produced quaternized octacationic water soluble metal-free, Ni, Co and Cu Pcs which were soluble in water, DMF, DMSO. The aggregation behaviour of these compounds were investigated in different concentrations of chloroform for metal-free, Ni, Co and Cu Pcs. The effect of solvents on absorption spectra were studied in various organic solvents. The novel compounds were characterized using IR, ¹H-, ¹³C NMR, UV–vis and MS spectral data.     

fac-Cobalt(III)-azido complexes derived from substituted pyridyl-based tridentate amines

Four new mononuclear triazido-cobalt(III) complexes [Co(L ^1/2/4 )(N₃)₃] and [Co(L ³ )(N₃)₃]·CH₃CN where L ¹  = [(2-pyridyl)-2-ethyl]-(2-pyridylmethyl)-N-methylamine, L ²  = [(2-pyridyl)-2-ethyl]-[6-methyl-(2-pyridylmethyl)]-N-methylamine, L ³  = [(2-pyridyl)-2-ethyl]-[3,5-dimethyl-4-methoxy-(2-pyridylmethyl)]-N-methylamine, and L ⁴  = [(2-pyridyl)-2-ethyl]-[3,4-dimethoxy-(2-pyridylmethyl)]-N-methylamine, respectively, were synthesized and structurally characterized. The four complexes were characterized by elemental microanalyses, IR and UV–VIS spectroscopy and X-ray single crystal crystallography. The complexes display two strong IR bands over the frequency region 2,020–2,050 cm^?1 assigned for the asymmetric stretching frequency, ν_a(N₃) of the coordinated azides indicating facial geometry. The molecular structure determinations of the complexes were in complete agreement with fac-[Co(L)(N₃)₃] conformation in distorted octahedral Co(III) environment.     

Cytotoxicity evaluation of coumarin derivatives containing 4-bromophenyl or anthracene moieties

The cytotoxic properties of four synthesized coumarin derivatives containing 4-bromophenyl or anthracene moieties against the human hepatocellular carcinoma cell lines (HepG-2) were investigated in vitro by use of the sulforhodamine B (SRB) assay. The four coumarin derivatives are 3-(4-bromophenyl)-benzo[5,6]coumarin (1a), 3-(4-bromophenyl)-7-(N,N-diethylamino)coumarin (1b), 3-(4-(anthracen-10-yl)phenyl)-benzo[5,6]coumarin (2a), and 3-(4-(anthracen-10-yl)phenyl)-7-(N,N-diethylamino)coumarin (2b). The preliminary results indicate that 1a, 2a, and 2b have significant cytotoxicity against HepG-2 whereas 1b has a growth-promotion effect.     

An approach to the synthesis of chemically modified bisazocalix[4]arenes and their extraction properties

Bisazocalix[4]arenes [N,N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)benzene (1), N,N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)biphenyl (2) and N,N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)-2,2′-dinitro biphenyl (3)] have been synthesized from 25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene by diazocoupling with the corresponding aromatic diamines (p-phenylenediamine, 4,4′-diamino biphenyl and 4,4′-diamino-2,2′-dinitrobiphenyl). Extraction studies of bisazocalix[4]arenes 1, 2, and 3 show no difference in their extraction behavior and selectivity, whereas azocalix[4]arenes are a poor extractant for heavy metal cations. The absorption spectra of the prepared bisazocalix[4]arenes are discussed, both the effect of varying pH and solvent upon the absorption ability of bisazocalix[4]arenes.     

Dinuclear nickel(II) complexes with Schiff base ligands: syntheses, structures and bio-relevant catalytic activities

Three Ni(II) complexes of cresol-based Schiff-base ligands, namely [Ni₂(L¹)(NCS)₃(H₂O)₂], (1) [Ni₂(L²)(CH₃COO)(NCS)₂(H₂O)] (2) and [Ni₂(L³)(NCS)₃] (3), (where L¹ = 2,6-bis(N-ethylpyrrolidineiminomethyl)-4-methylphenolato, L² = 2,6-bis(N-ethylpiperidineiminomethyl)-4-methylphenolato and L³ = 2,6-bis{N-ethyl-N-(3-hydroxypropyl iminomethyl)}-4-methylphenolato), have been synthesized and structurally characterized by X-ray single-crystal diffraction in addition to routine physicochemical techniques. Density functional theory calculations have been performed to understand the nature of the electronic spectra of the complexes. Complexes 1?C3 when reacted with 4-nitrophenyl phosphate in 50:50 acetonitrile?Cwater medium promote the cleavage of the O?CP bond to form p-nitrophenol and smoothly convert 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) either in MeOH or in MeCN medium. Phosphatase- and catecholase-like activities were monitored by UV?Cvis spectrophotometry and the Michaelis?CMenten equation was applied to rationalize all the kinetic parameters. Upon treatment with urea, complexes 1 and 2 give rise to [Ni₂(L¹)(NCS)₂(NCO)(H₂O)₂] (1??) and [Ni₂(L²)(CH₃COO)(NCO)(NCS)(H₂O)] (2??) derivatives, respectively, whereas 3 remains unaltered under same reaction conditions.     

Synthesis, crystal structure and antibacterial activity of a group of mononuclear manganese(II) Schiff base complexes

Five mononuclear complexes of manganese(II) of a group of the general formula, [MnL(NCS)₂] where the Schiff base L = N,N′-bis[(pyridin-2-yl)ethylidene]ethane-1,2-diamine (L¹), (1); N,N′-bis[(pyridin-2-yl)benzylidene]ethane-1,2-diamine (L²), (2); N,N′-bis[(pyridin-2-yl)methylidene]propane-1,2-diamine (L³), (3); N,N′-bis[(pyridin-2-yl)ethylidene]propane-1,2-diamine (L⁴), (4) and N,N′-bis[(pyridin-2-yl)benzylidene]propane-1,2-diamine (L⁵), (5) have been prepared. The syntheses have been achieved by reacting manganese chloride with the corresponding tetradentate Schiff bases in presence of thiocyanate in the molar ratio of 1:1:2. The complexes have been characterized by IR spectroscopy, elemental analysis and other physicochemical studies, including crystal structure determination of 1, 2 and 4. Structural studies reveal that the complexes 1, 2 and 4 adopt highly distorted octahedral geometry. The antibacterial activity of all the complexes and their respective Schiff bases has been tested against Gram(+) and Gram(−) bacteria.     

Synthesis and antimicrobial of some new substituted tetrazolomethylbenzo[d]-[1,2,3]triazole derivatives using 1H-benzo[d][1,2,3]triazole as starting material

A series of tetrazolomethylbenzo[d][1,2,3]triazole derivatives (2–14) have been synthesized and evaluated as antimicrobial agents from 1H-benzo[d][1,2,3]triazole (1) as starting material. The reaction of benzotriazole 1 with chloroacetonitrile afforded 2-(1H-benzo[d][1,2,3]-triazol-1-yl)acetonitrile 2, which was reacted with sodium azide to give tetrazole derivative 3. Esterification of benzotriazole 1 with ethyl bromoacetate in the presence of anhydrous potassium carbonate afforded ester 4, which was treated with hydrazine hydrate to afford the corresponding hydrazide 5. Reaction of 3 with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide afforded the nitro-glycoside derivative 6, which was deacetylated using methanolic ammonia to deprotected nitroglycoside 7. The hydrazide 5 was reacted with 4,5,6,7-tetrachlorophthalic anhydride or 1,2,4,5-benzenetetracarboxylic dianhydride in refluxing glacial acetic acid to give the corresponding imides 8 and 9, respectively. Also, the hydrazide 5 was reacted with carbon disulphide in ethanol to give potassium salt 10, which was reacted with hydrazine hydrate to afford aminotriazole derivative 11. The latter compound was reacted with carbon disulphide to afford thiadiazole derivative 12, which was treated with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide to give the thioglycoside derivative 13. Deacetylation of the thioglycoside 13 using methanolic ammonia solution at room temperature afforded the deprotected thioglycoside 14. The antimicrobial screening of some synthesized compounds showed that many of these compounds have good antimicrobial activities comparable to streptomycin and fusidic acid as reference drugs.     

Synthesis and antimicrobial activity of novel fused [1,2,4]triazino[5,6-<Emphasis Type="Italic">b</Emphasis>]indole derivatives

Synthesis of new fused systems of triazino[5,6-b]indole starting with preparation of 3-amino[1,2,4]-triazino[5,6-b]indole 1 by reaction of isatin with 2-aminoguanidinium carbonate in boiling acetic acid is presented [1]. Intermediate compound 1 reacted with aldehyde, ethyl chloroformate, triethyl orthoformate, and ninhydrine and gave new heterotetracyclic nitrogen systems, such as 3-(N ²-guanidinylimino)indole-2(1H)-one 2, 3-(N-ethoxycarbonylamino)-4H-[1,2,4]triazino[5,6-b]indole 3, 3-(N-ethoxymethyleneamino)-4H-[1,2,4]-triazino[5,6-b]indole 4, 3-(hydrazinothiocarbonylamino)-4H-[1,2,4]triazino[5,6-b]indole 5, respectively. N-(1,3-dioxoindene-2-ylidene)-4H-[1,2,4]triazino[5,6-b]indol-3-amine 6 was synthesized by reaction of compound 1 with aldehyde, ethyl chloroformate, triethyl orthoformate, and ninhydrine. New fused indole systems, pyrimido[2′,1′:3,4][1,2,4]triazino[5,6-b]indol-3(4H)-one 8, 9, 11, 12 and 1H-imidazo[2′,1′:3,4][1,2,4]triazino-[5,6-b]indol-2(3H)-one 10, were synthesized in the reaction of the intermediate 1 with bifunctional compounds. Structures of the products were elucidated from their elemental analysis and spectral data (IR, ¹H and ¹³C NMR and mass spectra). Antimicrobial activity of some synthesized compounds was tested.     

New long-chain-substituted polymeric metal-free and metallophthalocyanines by microwave irradiation: Synthesis and characterization

A tetranitrile monomer N,N-bis{2-[2-(3,4-dicyanophenoxy)ethoxy]ethyl}-4-methylbenzenesulfonamide (3) was synthesized by nucleophilic aromatic substitution of N,N-bis[2-(2-hydroxyethoxy)ethyl]-4-methylbenzenesulfonamide (1) onto 4-nitrophthalonitrile (2). The metal-free phthalocyanine polymer (4) was prepared by the reaction of a tetranitrile monomer 3 in 2-(dimethylamino)ethanol. Ni(II), Co(II) and Cu(II) phthalocyanine polymers were prepared by the reaction of the tetranitrile compound with the chlorides of Ni(II), Co(II) and Cu(II) in 2-(dimethylamino)ethanol (DMAE). The Zn(II)-phthalocyanine polymer was prepared by the reaction of the tetranitrile compound with the acetate of Zn(II) in DMAE. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–Vis, elemental analysis and MS spectral data.     

Comparative investigation of the copper(II) complexes of (R)-, (S)- and (R,S)-1-phenyl-N,N-bis(pyridine-3-ylmethyl)ethanamine along with the related complex of (R,S)-1-cyclohexyl-N,N-bis(pyridine-3-ylmethyl)ethanamine. Synthetic, magnetic, and structural studies

The interaction of the enantiopure (R)- and (S)-1-phenyl-N,N-bis(pyridine-3- ylmethyl)ethanamine ligands, R-L ¹ and S-L ¹ , with copper(II) chloride followed by addition of hexafluorophosphate resulted in the isolation of the corresponding enantiomeric complexes [Cu(R-L ¹ )Cl](PF₆) (1), [Cu(S-L ¹ )Cl](PF₆) (2) and [Cu(S-L ¹ )Cl](PF₆)??0.5Et₂O (3), in which dimerization occurs through two long Cu??????Cl interactions, the ??-chloro bridges being thus strongly asymmetric. The organic ligand is bound to the metal centre via its N₃-donor dipyridylmethylamine fragment in a planar fashion, such that each copper centre is in a square planar environment (or distorted square pyramidal with a long axial bond length if the additional interaction is considered). When R,S-L ¹ was employed in a parallel synthesis, the similar racemic complex [Cu(R,S-L ¹ )Cl](PF₆)??0.5MeOH (4) was obtained, in which the L ¹ ligands in each dimeric unit have opposite hands. In contrast to the complexes of L ¹ , the reaction of Cu(II) chloride with the related ligand, (R)-1-cyclohexyl-N,N-bis(pyridine-3-ylmethyl)ethanamine (R-L ² ), yielded the mononuclear complex [Cu(R,S-L ² )Cl₂] (5), displaying a distorted square pyramidal coordination geometry. The structure of this product along with its corresponding circular dichroism spectrum revealed that racemisation of the starting R-L ² ligand has occurred under the relatively mild (basic) conditions employed for the synthesis. A temperature-dependent magnetic studies of the complexes 1, 2 and 5 indicate that a week ferromagnetic interaction is operative in each dicopper core in 1 and 2 with 2J?=?1.2?cm^?1. On the other hand, a week antiferromagnetic intermolecular interaction is operative for 5.     

Synthesis and oxoanions (dichromate/arsenate) sorption study of N-methylglucamine derivative of calix[4]arene immobilized onto poly[(phenyl glycidyl ether)-co-formaldehyde]

The article describes synthesis as well as the evaluation of sorption properties of new N-methylglucamine substituted calix[4]arene and its poly[(phenyl glycidyl ether)-co-formaldehyde] immobilized product. Firstly, 5,17-bis-[(N-methylglucamine)methyl]-25,26,27,28-tetrahydroxy-calix[4]arene (3) was synthesized by the treatment of calix[4]arene with a secondary amine N-methylglucamine and formaldehyde via Mannich reaction. The immobilization of 3 onto poly[(phenyl glycidyl ether)-co-formaldehyde] to form calixarene based polymer (4) was carried out under suitable reaction conditions via nucleophilic substitution reaction. All the new compounds were characterized by a combination of FT-IR, ¹H-NMR spectroscopic and elemental analysis techniques. The sorption studies of 4 reveal that it is an excellent material for the removal of toxic oxoanions especially arsenate from aqueous environment. To understand the selectivity of 4, we also examined the retention of dichromate anions in the presence of Cl^?, NO₃ ^? and SO₄ ^2? anions at pH 1.5.     

Strukturelle Abwandlungen an Nukleotiden,Nukleosiden und Nukleosidbasen mit β-Acylvinylphosphoniumsalzen

β-Acetylvinyl-triphenylphosphonium bromide1 reacts with CMP to form the 3,N⁴-etheno-derivative {[6-(5′-phosphoribofuranosyl)-2-methyl-5-oxo-imidazo [1.2-c]pyrimidin-3-yl]-methyl}triphenyl-phosphonium bromide (2). Guanine affords mainly the lin. condensation product [(6-methyl-9-oxo-imidazo[1.2-a]-purin-7-yl)-methyl]triphenylphosphonium bromide (3) and the angular tricyclic product [(6-methyl-9-oxo-imidazo[2.1-b]purin-5-yl)-methyl]-triphenylphosphonium bromide (4). For comparison we synthesized the angular condensed heterocycle5, (6.8-dimethyl-9-oxo-imidazo[2.1-b]purin-5-yl)-methyl]triphenylphosphonium bromide, by reaction of 1-methylguanine with1, and the corresponding linear derivative6 [(4.6-dimethyl-9-oxo-imidazo[1.2-a]purin-7-yl)-methyl]-triphenylphosphoniumbromide from 3-methylguanine and1. AHofmann-type degradation of3 with the anion of diethyl malonate led to7, diethyl (6-methyl-9-oxo-imidazo[1.2-a]purin-7-yl)-methylmalonate, a compound whose structure resembles some Y-bases in t-RNA.Wittig reaction of the silylated nucleoside derivative8 a {[2-methyl-5-oxo-6-(2′.3′.5′-tris-trimethylsilyl)-ribofuranosyl-imidazo[1.2-c]pyrimidin-3-yl]methyl}-triphenylphosphonium bromide, with C₆H₅CHO resulted in the 2-methyl-3(ω-styryl)-6[2′.3′.5′-tris-(trimethylsilyl)]ribofuranosyl-imidazo[1.2-c] pyrimidin-5-one (9).