Zn(II) and Co(II) 3D Coordination Polymers Based on 2-Iodoterephtalic Acid and 1,2-bis(4-pyridyl)ethane: Structures and Sorption Properties

Metal-organic frameworks [M₂(2-I-bdc)₂bpe] (M = Zn(II) (1), Co(II) (2), 2-I-bdc = 2-iodoterephtalic acid, and bpe = 1,2-bis(4-pyridyl)ethane) were prepared and characterized by X-ray diffractometry. Both compounds retain their 3D structure after the removal of guest DMF molecules. Selectivity of sorption of different organic substrates from the gas phase was investigated for both complexes.     

On-line preconcentration of mercury by sorption on an anion-exchange resin loaded with 1,5-bis[(2-pyridyl)-3-sulphophenyl methylene] thiocarbonohydrazide and determination by cold-vapour inductively coupled plasma atomic emission

1,5-Bis[(2-pyridyl)-3-sulphophenyl methylene] thiocarbonohydrazide (PSTH) immobilized on an anion-exchange resin (Dowex) has been used for the on-line preconcentration of mercury from biological samples and waters prior to its determination by inductively coupled plasma atomic emission spectroscopy. The metal was eluted from the column using a solution of 2 M HNO(3) and mixed on-line with SnCl(2). The optimum experimental conditions were evaluated for the continuous preconcentration of Hg, the direct generation of mercury vapour and the final determination of this element by ICP-AES. The enrichment, together with low blank levels of the optimized procedure, allow the simple determination of this toxic element at concentrations down to a few nanograms per milliliter. The proposed method has a linear calibration range 5-1000 ng ml(-1) of mercury, with a detection limit of 4 ng ml(-1) (S/N=3) and a sampling rate of 40 h(-1), investigated with a 9 ml sample volume. The precision of the method (evaluated as the relative standard deviation obtained after analyzing ten series of ten replicates) was +/-3.6% at the 10 ng ml(-1) level of Hg(II) and +/-1.3% at the 100 ng ml(-1) level. The accuracy of the method was examined by the analysis of certified reference materials.     

Novel synthesis of 2,4-bis(2-pyridyl)-5-(pyridyl)imidazoles and formation of N-(3-(pyridyl)imidazo[1,5-a]pyridine)picolinamidines: nitrogen-rich ligands

Heating a neat 1:2 mixture of 2-picolylamine and 2-cyanopyridine followed by treatment of the resultant red gummy substance with aqueous KOH resulted in the isolation of 2,4,5-tris(2-pyridyl)imidazole (1a) as the major product and N-(3-(2-pyridyl)imidazo[1,5-a]pyridine)picolinamidine (2a) in small amounts. Similarly, by using 3-picolylamine, 2,4,-bis(2-pyridyl)-5-(3-pyridyl)imidazole (1b) and N-(3-(3-pyridyl)imidazo[1,5-a]pyridine)picolinamidine (2b) were isolated, and by using 4-picolylamine, 2,4,-bis(2-pyridyl)-5-(4-pyridyl)imidazole (1c) and N-(3-(4-pyridyl)imidazo[1,5-a]pyridine)picolinamidine (2c) were isolated. The plausible mechanism of the formation of 1a-c and 2a-c is delineated.     

On-line preconcentration of rhodium on an anion-exchange resin loaded with 1,5-bis(2-pyridyl)-3-sulphophenyl methylene thiocarbonohydrazide and its determination in environmental samples

A method for the determination of rhodium in different samples at trace levels is presented. The investigated metal is preconcentrated on a chelating resin microcolumn (1,5-bis(2-pyridyl)-3-sulphophenyl methylene thiocarbonohydrazide (PSTH) immobilized on an anion-exchange resin (Dowex 1×8-200)) placed in the autosampler arm. The modification of the autosampler in the tubing line and circuit allowed either the flow of the sample through the column or the operation of the autosampler in the normal mode, where microlitres of 4 M HNO₃, which acts as the elution agent, pass through the microcolumn eluting Rh(III), which is directly deposited in the graphite tube as drop of a precisely defined volume. The detection limit is 0.3 ng ml⁻¹. Linearity is maintained in the concentration range 0-50 ng ml⁻¹ for rhodium, with correlation factor of 0.999 and relative standard deviation of 1.8% for 10 ng ml⁻¹ of Rh. The effects of various parameters such as pH, concentration and volume of eluent, sample loading time, sample flow rate and interference of a large number of metal ions and anions on the determination of this metal was studied in detail to optimize the conditions for their determination in various samples. The method is found to be highly selective, fairly sensitive, simple, rapid and economical and may be safely applied to their determination in different complex materials such as environmental samples and catalysts.     

Electrochemical properties of dinuclear [Ru([n]aneS4)] complexes of 2,3-bis(2-pyridyl)pyrazine

The syntheses of three new dinuclear [Ru([n]aneS(4))] complexes, where n = 12, 14, 16, bridged by the ligand 2,3-bis(2-pyridyl)pyrazine, (dpp) are reported. The absorption spectra of the complexes show changes in the energy of the MLCT bands within the series, indicating that the thiacrown ligands stabilise the Ru(II) oxidation state to different degrees. Electrochemical studies are also consistent with these observations, and reveal that the pi-acceptor properties of [n]aneS(4) ligands lead to metal based oxidation couples occurring at potentials that are more anodic than those observed in the analogous dinuclear [Ru(bpy)(2)](2+) complex. Despite the back-bonding properties of the thiacrown ligands leading to a reduction in ligand-bridge mediated metal-metal coupling, electrochemical interactions between the metals are still considerable.     

Complex formation of copper(II) and palladium(II) with L,L-3,7-bis[2-(4-hydroxyphenyl)-1-(methoxycarbonyl)ethyl]-1,5-di(ethoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonan-9-one

Complexation of copper(II) chloride, copper(II) triflate, and palladium(II) chloride with optically active L,L-3,7-bis[2-(4-hydroxyphenyl)-1-(methoxycarbonyl)ethyl]-1,5-di(ethoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonan-9-one was studied.     

3-(2-Pyridyl)-[1,2,3]triazolo[1,5-a]pyridines. An experimental and theoretical (DFT) study of the ring-chain isomerization

An experimental ((1)H NMR) and theoretical (DFT) study of the ring-chain-ring isomerization of 3-(2-pyridyl)-[1,2,3]triazolo[1,5-a]pyrid-7-yl derivatives (A) into 6-{[1,2,3]triazolo[1,5-a]pyrid-3-yl}-2-pyridyl derivatives (B) has been carried out. Based on the calculations, a mechanism of several steps will be proposed. The experimental results as well as the calculations lead to the conclusion that the A-B ratio depends on the electronic properties of the substituents.     

Synthesis of some 1,3-disubstituted imidazo[1,5-a]pyridines using 2-cyanopyridine

Heating 2-cyanopyridine and hydrazine hydrate at 100 °C and reheating the resultant liquid with pyridine-2-carboxaldehyde yielded a red semi-solid. On adding aqueous KOH, a mixture of 1-(3,5-bis(2-pyridyl)-1,2,4-triazolyl)-3-(2-pyridyl)imidazo[1,5-a]pyridine (2a) and 1-((2-pyridyl)methanimine)-3-(2-pyridyl)imidazo[1,5-a]pyridine (2b) precipitated and from the filtrate 3,5-bis(2-pyridyl)-1,2,4-triazole (1) was isolated. Similar compounds were obtained from two other pyridinecarboxaldehydes.     

Determination of cadmium in biological samples by inductively coupled plasma atomic emission spectrometry after extraction with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide.

An inductively coupled plasma atomic emission spectrometric method for the determination of trace amounts of cadmium after extraction of the metal into isobutyl methyl ketone containing 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide is described. The optimum extraction conditions were evaluated from a critical study of the effects of pH, concentration of extractant, shaking time and ionic strength. The detection limit for cadmium is 0.1 ng ml-1 and the calibration is linear from 0.2 to 140 ng ml-1. The relative standard deviation for ten replicate measurements is 2.9% for 2 ng ml-1 of cadmium. Results from the analysis of some certified biological reference materials are given.     

Copper(II) complexes of a series of polypyridine ligands possessing a 1,2-bis(2-pyridyl)ethane common moiety: incorporation and hydrolysis of phosphate esters

Two tetradentate ligands 1,2-bis[2-((dimethylamino)methyl)-6-pyridyl]ethane (L1) and 1,2-bis[2-(N-piperidinomethyl)-6-pyridyl]ethane (L2) and a hexadentate ligand 1,2-bis(2-((methyl(pyridylmethyl)amino)methyl)-6-pyridyl)ethane (L3) were prepared as part of a series of new polypyridine ligands possessing a 1,2-bis(2-pyridyl)ethane common moiety. L1 and L2 form mononuclear Cu(II) complexes [Cu(L)(Cl)](ClO4) [L = L1 (1) and L2 (2)], respectively. L3 forms a dinuclear Cu(II) complex [Cu2(L3)((PhO)2PO2)2](ClO4)2 (3) or a hexanuclear Cu(II) complex [Cu6(L3)3((PhO)PO3)4](ClO4)4 (4) in the presence of (PhO)2PO2- monoanion or (PhO)PO3(2-) dianion, respectively. The structures of 1-4 were determined by X-ray analysis. The structures in solution were investigated by means of FAB and CSI MS spectrometers. The structural flexibility of the common 1,2-bis(2-pyridyl)ethane moiety and of the pendant groups allows complexes 1-4 to adapt to the various structures. Each Cu ion in 1 and 2 adopts a square pyramidal geometry with one Cl ion and two pendant groups (L1 and L2) binding in a bis-bidentate chelate mode. There is no steric repulsion between the pendant groups, so that the ligands specifically stabilize the mononuclear structures. L3 binds two Cu(II) ions with two pendant groups in tridentate chelate modes and, with the incorporation of phosphate esters, various dinuclear units are formed in 3 and 4. In 4, a dinuclear unit of [Cu2(L3)]4+ links two dinuclear units of [Cu2(L3)(PhOPO3)2] with four (mu3)-1,3-PhOPO3(2-) bridges. The hydrolytic activity of 2 and a dicopper(II) complex of L3 was examined with tris(p-nitrophenyl) phosphate (TNP) as a substrate.     

Determination of cadmium in biological samples by inductively coupled plasma atomic emission spectrometry after extraction with 1,5-bis[phenyl-(2-pyridyl)methylene]-thiocarbonohydrazide

A systematic study was made of the optimum conditions for cadmium determination in biological samples by ICP-AES after extraction of the metal into methyl isobutyl ketone containing 1,5-bis[phenyl-(2-pyridyl)methylene]-thiocarbonohydrazide. The maximum volume ratio of aqueous to organic phase was 30 1 for a single-stage extraction of 99–100% of the metal ion. The detection limit was 0.3 ng/ml cadmium, and the calibration was linear from 0.4 to at least 150 ng/ml. No interferences from the elements commonly found in biological materials were observed. A precision of 2.5% (P = 0.05) at the 2 ng/ml level of the metal was achieved. The accuracy of the method was demonstrated by analysis of three standard reference materials, giving concentrations of 1.90 ± 0.43, 27.1 ± 1.4 and 2.63 ± 0.38 /g of cadmium, compared with the certified values of 2.20 ± 0.10, 26.3 ± 2.1, and 2.71 ± 0.15 g/g, respectively.     

Synthesis and luminescent properties of iridium(III) ionic binuclear complexes with 1,4-bis[2-(2-pyridyl)benzimidazolato]butane as a bridging ligand

New ionic binuclear complexes of iridium(III) containing 1,4-bis[2-(2-pyridyl)benzimidazolato]butane as a bridging ligand were synthesized. These compounds exhibit intensive photo- and electroluminescence of yellow-green, green-yellow, and pink colors. The maximal electroluminescence brightness was 4565 cd/m².     

Derivatives of carbohydrazide, thiocarbohydrazide and diaminoguanidine as photometric analytical reagents-I 1,3-bis[(2-pyridyl)methyleneamino]thiourea and 1,3-bis[(2-pyridyl)methyleneamino]guanidine

1,3-Bis[(2-pyridyl)methyleneamino]thiourea (PMAT) and 1,3-bis[(2-pyridyl)methyleneamino]-guanidine (PMAG) have been prepared. They have been examined and characterized by infrared and ultraviolet spectroscopy. A spectrophotometric method has been used for determination of the protonation constants of the reagents. Finally, a spectrophotometric survey has been made of the reactions of various cations with PMAT and PMAG.     

Pseudopolymorphism of [2,5-bis(2-pyridyl)­pyrazine]­ferrocenyl(methyl)­boron hexa­fluoro­phosphate

Two pseudopolymorphs of [2,5-bis(2-pyridyl)­pyrazine]­ferrocenyl­(methyl)­boron hexa­fluoro­phosphate have been determined at 173 K, namely the diethyl ether hemisolvate, [Fe(C₅H₅)(C₂₀H₁₇BN₄)]PF₆·0.5C₄H₁₀O, (I), which forms red crystals with Z′ = 1, and the aceto­nitrile hemisolvate, [Fe(C₅H₅)(C₂₀H₁₇BN₄)]PF₆·0.5CH₃CN, (II), which yields green–brown crystals with Z′ = 2. Despite the different crystal packing, the cations in (I) and (II) are similar. The 2,5-bis(2-pyridyl)­pyrazine moiety is almost planar and displays bending along its long axis compared with free 2,5-bis(2-pyridyl)­pyrazine. It is remarkable that both crystals were obtained from the same aceto­nitrile/diethyl ether solution.     

Preparation of palladium complexes of 1,3-di(2-pyridyl)propane derivatives and their use in norbornene polymerization

A variety of neutral palladium(II) complexes [Pd(L–L)Cl₂] containing 1,3-di(2-pyridyl)propane (1), 1,3-bis(2-pyridyl)-2-pentylpropane (2), 1,3-bis(2-pyridyl)-2-phenylpropane (3a), 1,3-bis(2-pyridyl)-2-tolylpropane (4), and 1,3-bis(2-pyridyl)-2-ferrocenylpropane (5) as chelate ligands (L–L) have been synthesized. The crystal structures of 1,3-diphenyl-2,4-di-pyridin-2-yl-butan-1-ol (3b), 5, [(2)PdCl₂], [(4)PdCl₂], and [(5)PdCl₂] have been determined and show a square planar geometry at palladium(II). The neutral complexes were tested in the polymerization of norbornene and copolymerization of norbornene with norbornene derivatives. The complex bearing the pentyl group exhibited high reactivity to give up to 5.9×10⁵ in molecular weight for the homopolymerization. When [(4)PdCl₂] or [(5)PdCl₂] was used as a catalyst, homopolymers insoluble at 150 °C in trichlorobenzene were obtained. However, copolymerization of norbornene with norbornene derivatives 8a–d catalyzed by [(4)PdCl₂] gave soluble copolymers with molecular weights up to 5.1×10⁵.     

Facile Preparation of 3,7-Diazabicyclo[3.3.0]octane and 3,7,10-Triheterocyclic [3.3.3]Propellane Ring Systems from 1,5-Diazacyclooctane 3,7-Derivatives(1)

The cyclodimerization of p-toluenesulfonamide and 3-chloro-2-(chloromethyl)-1-propene to prepare N,N'-bis(p-toluenesulfonyl)-3,7-bis(methylene)-1,5-diazacyclooctane (1a) and its ozonation to the corresponding 3,7-dione 2a are reported. Unusual transannular cyclizations initiated by lithium aluminum hydride treatment or bromination of 1a and oxidative coupling of the dioxime derived from 2a are described. These reactions lead, respectively, to the following derivatives of the little-studied 3,7-diazabicyclo[3.3.0]octane ring system: 1,5-dimethyl-3,7-diazabicyclo[3.3.0]octane (5), N,N'-bis(p-toluenesulfonyl)-1,5-bis(bromomethyl)-3,7-diazabicyclo[3.3.0]octane (8), and N,N'-bis(p-toluenesulfonyl)-1,5-dinitro-3,7-diazabicyclo[3.3.0]octane, (12). Acid-catalyzed hydration of 1a, in contrast, gives the expected 5-methyl-3,7-diazabicyclo[3.3.1]nonan-1-ol (10). Reaction of the dibromide 8 with the nucleophiles, sodium sulfide, sodium oxide, and sodium p-toluenesulfonamide conveniently delivers the corresponding novel 3,7,10-triheterocyclic [3.3.3]propellanes.     

Reaction of (dichloro)(1,5-cyclooctadiene)platinum(II) with dimethyl diazomethylphosphonate. Crystal structure analysis of a bis-insertion product, (R,R)-bis[chloro(dimethoxyphosphonyl)methyl]-(1,5-cyclooctadiene)platinum(II)

The reaction of dichloro(1,5-cyclooctadiene)platinum(II), 1 with dimethyl diazomethylphosphonate, 2, results in the formation of products of insertion of the carbene moiety into one or both PtCl bonds. An X-ray diffraction study of a crystal obtained from the major bis-insertion product of this reaction shows it to be (R,R)-bis[chloro(dimethoxyphosphonyl)methylyl](1,5-cyclooetadiene)platinum(II), 5. The space group is polar indicating that spontaneous resolution has occurred upon crystallization.     

二苯并[b,f][1,5]二氮杂芳辛四烯衍生物的合成及拆分

以邻氨基二苯甲酮为原料,经自身缩合环化合成了3种二苯并[1,5]二氮杂芳辛四烯衍生物(1a~1c);以邻苯二甲酸酐和溴苯为原料经傅-克反应制得中间体2-(4-溴苯甲酰溴)苯甲酸(M1);M1经叠氮化后自缩合制得6,12-二(4-溴苯基)二苯并[b,f][1,5]二氮杂环辛四烯(1d);以邻氨基苯甲酸甲酯为原料,经自身缩合环化制得中间体二苯并[b,f][1,5]二氮杂环辛四烯-6,12(5H,11H)-二酮(M2);M2经氯化合成6,12-二氯二苯并[b,f][1,5]二氮杂环辛四烯(1e),化合物1a~1e的结构经~1H NMR,~(13)C NMR和ESI-MS表征,其中化合物1c为新化合物。利用超临界色谱(SFC)技术对化合物1a~1e实现了手性拆分,获得5对具有高旋光度的光学活性异构体(ee99%)。     

Polystyrene bis[N-(2-pyridyl) sulfonamide] palladium(II): Synthesis,characterization as a catalyst for coupling reactions

The [N-(2-pyridyl)] para-styrene sulfonamide (PSS) was prepared as a monomer, from the reaction of para-styrene sulfonyl chloride and 2-amino pyridine in the presence of potassium hydroxide solution 0.5 M as a base, and CH₃Cl. Polystyrene [N-(2-pyridyl) sulfonamide] (PPSS) was synthesized from the polymerization of [N-(2-pyridyl)] para-styrene sulfonamide (PSS). The Polystyrene bis [N-(2-pyridyl) sulfonamide] palladium (II) as a polymer- supporting palladium complex was also prepared from the reaction of PdCl₂ (CH₃CN)₂ with PPSS in the presence of KOH 0.5 M. Polystyrene bis [N-(2-pyridyl) sulfonamide] palladium (II) is produced as a novel heterogeneous catalyst for coupling reactions for C-C bond formation. This method includes higher yield and has an easier work-up procedure. The structures of the monomer, polymer and its Pd complex were confirmed by using FT-IR and ¹H-NMR spectroscopy. Elemental analysis of Pd by inductively coupled plasma (ICP) technique and hot filtration test showed loading of the metal into solution from the catalyst The heterogeneous catalyst was recycled without any loss in its properties.     

Synthesis and Characterization of 2,5-Bis(2-pyridyl)thiophene

2-[2-(Trimethylsilyl)ethynyl] pyridine ( 6 ) was prepared in 95% yield by reaction of 2-bromopyridine with trimethylsilylacetylene in triethylamine in the presence of bis(triphenylphosphine)Palladium(II) chloride and Copper(I) iodide. Desilylation of ( 6 ) by refluxing with sodium hydroxide in methanol (yield 95%) of 2-ethynylpyridine ( 5 ). Oxidative coupling of ( 5 ) in pyridine by oxygen in the presence of Copper(I) chloride gives 70% yield of 1,4-bis(2-pyridyl)1,3-butadiyne ( 4 ). Reaction of 4 with sodium sulfide affords 100% of 2,5-bis(2-pyridyl) thiophene ( 1 ).