Synthesis and characterization of oxazolone complexes with Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) in different counterions

Oxazolone forms (1:1) complexes with Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ chlorides, as well as forms (1:1) complexes with Co²⁺ and Cu²⁺ acetates. All the complexes are found to be non-electrolytes in DMF; tetrahedral, square-planar and octahedral structures are assigned to them based on electronic and magnetic data. IR studies reveal that the complexes are formed by donating the lone-pair electron from O and N atoms to the metal ion. The thermal decomposition of the [ML·mX·nH₂O]_y·H₂O chelates was studied by TG–DTA techniques. The mechanism of the decomposition has been established from TG–DTA data. The kinetic parameters, activation energy (E_a) and pre-exponential factor (A), were calculated from TG curves using Coats and Redfern method. Relative thermal stabilities of the chelates have been evaluated on the basis of these parameters.     

Modification of 4-(2-pyridylazo)-resorcinol postcolumn reagent selectivity through competitive equilibria with chelating ligands

Aminopolycar☐ylate ligands were added to the 4-(2-pyridylazo)-resorcinol (PAR) postcolumn reagent to alter the reagent selectivity towards transition metals. Addition of ethylenediaminetetraacetic acid (EDTA) completely suppressed the reaction between PAR and the metal ions. Addition of 0.1 mM nitrilotriacetic acid (NTA) to 1 mM PAR lowered the response to specific transition metal ions, but completely suppressed the PAR response to the lanthanides. Increasing the NTA concentration to 8 mM resulted in complete suppression of the PAR response to all metal ions except Cu²⁺ and Co²⁺ for which the detection limits were 3 and 1 ng, respectively. The observed selectivity results from the slow rate of conversion of metal ions from the M(NTA)₂⁴⁻ form to M(PAR)₂.     

Complexation metallique des imides. II. Grandeurs thermodynamiques de formation des complexes de Ag(I), Cd(II), Co(II), Ni(II), Cu(II), Zn(II) avec l''hydantoine

Thermodynamic values for the formation of complexes of Ag⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺ ions with hydantoïn were determined at 25°C in aqueous medium 0.5 M KNO₃. Stability constants were calculated from pH metric measurements while corresponding standard enthalpies were deduced from direct calorimetric determinations. The results are interpreted and compared to those of succinimide complexes previously studied.     

Co(II), Ni(II) and Cu(II) metal complexes with a N8 azamacrocyclic ligand

Hydrated nitrate and perchlorate salts of the transitional metal ions Co²⁺, Ni²⁺ and Cu²⁺ have been used to investigate the coordination capability of the octaaza macrocycle L derived from 2,6-diformylpyridine and diethylenetriamine. The synthesis of the metal complexes was carried out in 1:1 and 2:1 metal:ligand molar ratios, but dinuclear complexes were obtained in all cases due to the size of the 24-membered ligand. The complexes have been characterized by elemental analysis, molar conductivity, mass spectrometry, IR spectroscopy, diffuse reflectance and magnetic measurements. The dinuclear nature of the compounds was confirmed by X-ray diffraction. The crystal structures of [Ni₂L(NO₃)₂](NO₃)₂, [Cu₂L(NO₃)₄] and [Cu₂L(ClO₄)₄], were determined.     

Formation of cobalt, nickel and copper complexes with murexide in ethanol-water mixtures

The complexation reactions between murexide and Co²⁺, Ni²⁺ and Cu²⁺ in C₂H₅OH-H₂O mixtures have been investigated spectrophotometrically. The formation constants of the 1:1 complexes formed increase in the order Co²⁺ < Ni²⁺ < Cu²⁺ for all solvent mixtures studied, and log K_f is a linear function of the mole fraction of ethanol. The heat of complexation was determined calorimetrically for the nickel and copper complexes. The values of ΔH° and ΔS° are solvent-dependent, and all three complexes have negative ΔH° and positive ΔS° values.     

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.     

吡啶取代的Lindqvist型多酸的线性和非线性光学性质及阳离子检测功能的理论研究

采用密度泛函理论B3LYP方法计算了吡啶取代的Lindqvist型多酸(POMs)的线性(最大吸收波长, λ_max)和非线性光学(NLO)[超瑞利散射(HRS)的第一超极化率, β_HRS]性质, 探讨了其作为潜在阳离子检测剂的可能性. 金属离子吸附能计算结果表明, 吡啶取代的Lindqvist型多酸配体与金属离子之间均有较强的相互作用, 相互作用强度大小顺序为Ni²⁺>Cu²⁺>Co²⁺>Fe²⁺>Zn²⁺>Mg²⁺>Ca²⁺. 电子光谱和β_HRS计算结果表明, 引入适当的供、 受电子基团对该多酸配体进行修饰可有效调节线性和二阶NLO性质; 同时, 吡啶取代的Lindqvist型多酸对7种金属离子(Cu²⁺, Zn²⁺, Ca²⁺, Mg²⁺, Ni²⁺, Co²⁺, Fe²⁺)表现出了不同的检测行为.     

基于有机-无机介孔二氧化硅杂化材料对Cu^2和Co2+的选择性测定

合成了一种有机-无机介孔二氧化硅杂化材料(SBA-15-Tpy),通过透射电镜显微镜、X射线衍射、热重分析和N_2吸附-解吸曲线对其进行表征,并基于该材料建立了在水中对Cu²⁺和Co²⁺的选择性识别。研究表明,SBA-15-Tpy与Cu²⁺和Co²⁺结合后会分别在800 nm和510 nm处产生新的吸收峰,加入其它金属离子后不发生明显的吸收峰值变化。在最优条件下,检测Cu²⁺和Co²⁺的线性范围分别为2.0~200.0μmol/L和10.0~200.0μmol/L,检出限分别为0.48μmol/L和4.28μmol/L。将上述方法用于江水中Cu²⁺和Co²⁺的测定,回收率在96.0%~108.5%之间。     

Preparation and Characterization of Heteropoly Octadecamolybdodiphosphates

Heteropoly molybdophosphates with general formula M(?)P2Mo18O62 ·xH2O, where M = H+, K+, NH4+, Ca2+, Co2+, Ni2+, Cu2+, Zn2+ and Ag+, were prepared and characterlzed by elemental analysis, IR and UV spectrometry and thermal analysis. The solubilities of the compounds were examined. The IR spectra show that the countercations and the crystallization water have an influence upon the vibration frequencies of vMo-Oc and vMo-Oc-Mo·In the UV spectra, the charge-transfer bands are assigned to e→e and e→b2 transition. All the compounds decompose at 328-534℃.     

Synthesis of tripodal aza crown ether calix[4]arenes and their supramolecular chemistry with transition-, alkali metal ions and anions

Tripodal aza crown ether calix[4]arenes, 5a, 5b, 6a and 6b, have been synthesized. The structure of protonated 5a was elucidated by X-ray crystallography to be a self-threaded rotaxane. Complexation studies of 5a and 5b towards anions using Na⁺ as countercation were carried out by ¹H NMR titration in dimethylsulfoxide-d₆ and the mixture of chloroform-d and methanol-d₄, respectively. Ligands 5a and 5b were able to form 1:1 complexes with Br⁻, I⁻ and NO₃⁻ and the complexation stability varied as follows: NO₃⁻>I⁻>Br⁻. The effect of countercation on anion complexation was also investigated. The results showed that the association constants of 5a towards Br⁻ in the presence of various cations varied as K⁺>Bu₄N⁺>Na⁺. The enhancement in anion complexation ability of 5a may result from the rearrangement of the tripodal ammonium unit in the presence of K⁺. The neutral forms, 6a and 6b, were able to form complexes with transition metal ions such as Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺. The stability of the complexes followed the sequence: Ni²⁺2+Cu²⁺Zn²⁺. Compounds 6a and 6b may, therefore, potentially be used as either transition metal ion or anion receptors that can be controlled by pH of the solution.     

第四周期过渡金属钼磷三元杂多化合物的氧化还原性质研究

研究了Keggin结构钼磷杂多化合物Na₅[PM(H₂O)Mo₁₁O₃₉]·nH₂O(M=Mn²⁺,Co²⁺,Ni²⁺,Cu²⁺,Zn²⁺在溶液中的氧化还原性质,发现环境的改变可对杂多阴离子的极谱半波电位产生影响,其影响程度的大小决定于过渡金属离子本身的性质。取代后的钼磷杂多阴离子的半波电位顺序为Ni²⁺>Co²⁺>Zn²⁺>Cu²⁺>Mn²⁺,pH值的变化影响氧化还原性质,并阐述了变价金属Cu²⁺对杂多阴离子氧化还原性质的影响.     

Synthesis and fluorescence behaviour of crown and azacrown ethers carrying the dansyl fluorophore as a pendant in acetonitrile solution

The influence of Li⁺, Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Pb²⁺ and Al³⁺ ions on the spectroscopic properties of the dansyl group covalently linked to crown ether or diazacrown ethers was investigated by means of absorption and emission spectrophotometry. Interaction of the alkali metal ions with all fluoroionophores studied is weak, while alkaline earth metal ions interact strongly causing about 50% quenching of dansyl fluorescence of A21C5-Dns and A₂18C6-Dns. The Cu²⁺, Pb²⁺ and Al³⁺ cations interact very strongly with dansyl chromophore regardless the crown ether type, causing a major change in absorption spectrum of the chromophore and forming non-fluorescent complexes. The Co²⁺, Ni²⁺, Zn², Mg²⁺ and Ag⁺ cations interact moderately with all fluoroionophores studied causing about 20% of fluorescence quenching of dansyl, except for a strong dansyl fluorescence quenching of 15C5-Dns by Co²⁺ ion. The quenching efficiency of didansylated fluoroionophores by the alkali metal ions and alkaline earth metal ions is weaker than monodansylated ones.     

铜离子与SALI3-2蛋白的相互作用

用1/2 MS固体培养基培养拟南芥幼苗, 研究了CuCl₂对转Sali3-2基因植株生长的影响, 发现转基因植株Sali3-2的表达可提高其耐受Cu²⁺胁迫的能力. 进一步克隆Sali3-2基因, 表达并纯化了缺失信号肽的 SALI3-2 蛋白. 利用固定金属离子亲和色谱(IMAC)分析发现, Cu²⁺ 能够与 SALI3-2 蛋白结合. 通过荧光光谱及圆二色光谱(CD)进一步研究了Cu²⁺ 与 SALI3-2 蛋白间的键合机理. 结果表明, Cu²⁺ 可引起SALI3-2 蛋白内源性荧光猝灭, 其猝灭机制为静态猝灭; Cu²⁺ 与SALI3-2 蛋白的结合常数为8.89×10⁶, 结合位点数为1.6. CD分析显示, Cu²⁺ 与SALI3-2 蛋白的结合未使SALI3-2 蛋白二级结构发生明显改变. 由此推测, 在高浓度铜离子胁迫下, SALI3-2蛋白通过结合一定数量的Cu²⁺使蛋白的构象发生改变, 这可能是SALI3-2蛋白的表达使植物耐受Cu²⁺胁迫能力提高的分子机制之一.     

A highly selective chemosensor for copper ion based on ICT fluorescence

Simple structural compounds 1 to 3 were synthesized.The presence of Cu²⁺ resulted in the fluorescence and absorption spectra change of 1 and 2,which indicated that 1 and 2 showed a highly selective response to Cu²⁺ over other metal ions.However,3 showed no selectivity for metal ions,which means that the compound could bind with several metal ions,such as,Ni²⁺,Zn²⁺,Cd²⁺.Hg²⁺, Pb²⁺,Fe³⁺,Mg²⁺,Ca²⁺,and Co²⁺,except Cu²⁺ and Ag⁺.The different spectral responses were attributed to the difference in binding sites for 1 and 3.     

Coordination properties of 1-allyl-2-methylimidazole relative to some metal ions in the solid state and aqueous solution

Cobalt(II) and copper(II) complexes with 1-allyl-2-methylimidazole (L), of general formula [ML₂(NO₃)₂], have been prepared in the solid state. The compounds were characterised by structural, spectroscopic and magnetic measurements. The metal ions in both six coordinate complexes are surrounded by two nitrogen atoms of the imidazole rings and four oxygen atoms of the chelating nitrato group (the CoN₂O₄ and CuN₂O₄ chromophores). The structure of both chromophores is described by a very distorted tetragonal bipyramid. The formation of successive complexes of the azole with Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Cd²⁺ in aqueous solution was followed potentiometrically. An irregularity in the K_n constants of successive Co²⁺ and Zn²⁺ complexes suggests a change in the coordination sphere of the central ions from octahedral to tetrahedral. With the Co²⁺–1-allyl-2-methylimidazole system, the change has been proven by inspection of the visible absorption spectra.     

6-(N,N-Dimethylamino)-2-naphthoylacryl Acid: a Highly Selective and Sensitive Fluorescent Sensor of Copper(II)

A novel fluorescent probe, 6-(N,N-dimethylamino)-2-naphthoylacryl acid(ACADAN) was designed and synthesized as a fluorescent sensor for Cu²⁺ in aqueous media. Significant amplification of fluorescence signals without causing any discernible change of maximum fluorescence emission wavelength(λ_max) was observed upon the addition of Cu²⁺. Importantly, ACADAN is capable of recognizing Cu²⁺ selectively in aqueous media in the presence of various biologically relevant metal ions and the prevalent toxic metal ions in the environment with high sensitivity(detection limit was 0.1 μmol/L).     

过渡金属取代型杂多阴离子柱撑水滑石上环己烯的催化氧化性能

类水滑石及杂多阴离子柱撑水滑石具有可调变的二维孔道结构,活性组分可在较宽的范围内进行调变,从而使其成为有应用前景的氧化催化剂'·'．迄今,以完整结构形态的水滑石为催化剂的催化氧化研究尚未见报道．我们发现［'－'j,含可变价元素的类水滑石和过渡金属取代型杂多阴离子柱撑水滑石具有在较低温度下活化分子氧,从而实现活泼烃类a－H氧化的能力·本文报道了M。AIXW;;ZO。。（M＝Mg'",Zn'";X＝p,St;Z＝Mn2＋,Fe2＋,C。2＋,Ni'",Cll'"）层柱材料上环己烯的催化氧化行为．1实验部分M。AI－XW;;ZO。。系列杂多…     

Handling of electronic absorption spectra with a desk-top computer-II: calculation of stability constants from spectrophotometric titrations

A fully automatic system for combined spectrophotometric and pH titrations was described in Part I. Its performance in the titration of weak acids and metal complexes is discussed, along with a computer program for numerical treatment of the data, based on Marquardt's modification of the Newton—Gauss non-linear least-squares method. The deprotonation of p-nitrophenol at concentrations of 4 × 10⁻⁵ and 4 × 10⁻⁶M was studied in order to test the sensitivity. Results identical within the reproducibility of the pH-meter were obtained: pK^H = 7.00 ± 0.01 and 7.02 ± 0.01, respectively. Three complexation reactions were studied: (1) the interaction of SCN⁻ with the Co²⁺ complex of 1,4,8,11-tetramethyl-1,4,8,11-tetra-azacyclotetradecane (TMC); five independent experiments gave pK [CoTMC (SCN)⁺ CoTMC²⁺ + SCN⁻] = 3.099 ± 0.003: (2) the deprotonation of the Cu²⁺ complex of 3,7-diazanonanediamide (DANA); five experiments gave pK (CuDANA²⁺ CuDANAH⁺₋₁ + H⁺) = 7.14 ± 0.01 and pK (CuDANAH⁺₋₁ CuDANAH₋₂ + H⁺) = 8.38 ± 0.01: (3) for the reaction of Cu²⁺ with 1,3,7-triazacyclodecane (L), data from different ligand: metal ratios had to be combined to obtain pK (CuL²⁺ Cu²⁺ + L) = 16.19 ± 0.01, pK (CuL²⁺₂ CuL²⁺ + L) = 10.30 ± 0.01, and pK (Cu₂L₂ (OH)²⁺₂ 2 CuL²⁺ + 2 OH⁻) = 14.58 ± 0.03. Titration curves with a total change in absorbance of as little as 0.03 units could be analysed satisfactorily, extending considerably the useful range of concentrations for spectrophotometric titrations. In combined spectrophotometric/pH titrations the accuracy of the glass electrode is normally the limiting factor. Other equilibrium constants can easily be reproduced with standard errors of less than 0.01 log unit.     

Magnetic study of highly conductive TCNQ salts of Cu(II) complexes with 2,2''-bipyridine, 1,10-phenanthroline and ethylenediamine

The magnetic susceptibility has been determined for CuL_n(TCNQ⁻)₂ (L = 2,2'-bipyridine, 1,10-phenanthroline, or ethylenediamine;n = 1 or 2), having high electric conductivity. The results show that the Cu²⁺L_n chelates are partially reduced to Cu²⁺L_n in the complexes. The equilibrium Cu²⁺L_n(TCNQ⁻)₂ Cu⁺L_n(TCNQ⁻)(TCNQ^o) produces conduction electrons in TCNQ columns.     

CHARACTERIZATION OF SOME SCHIFF BASES OF HETEROCYCLIC COMPOUNDS AND THEIR TRANSITION METAL COMPLEXES

Some new Schiff bases were synthesized by the condensation ofequimolar quantities of salicylaldehyde and 2-amino-5-phenylazo-pyridine orits derivatives in dry benzene(1):Metal complexes of the type ML_2and M'L_3where M=Cu~(2+),Co~(2+),Ni~(2+),Mn~(2+)Pd~(2+),M'=Fe~(3+)and L=different newly synthesizedmonobasic Schiff bases were prepared in absolute ethanolic medium(2)andcharacterized by elementary analysis,conductance measurements,infraredspectra,electronic spectra,magnetic moments studies.