An unusual ring transformation: Reaction of phenyl 4-chromone-3-sulfonate with methyl 3-aminocrotonate

The novel benzoxathiinopyridines 8 and 9 were synthesized by ring transformation of phenyl 4-chromone-3-sulfonate ( 1 ) with methyl 3-aminocrotonate ( 2 ). The structures of 8 and 9 were determined by spectroscopic methods and the reaction courses for the formation of these compounds are discussed.     

Thermal decomposition of Y,La and lanthanide benzene-1,2-dioxyacetates in an air atmosphere

The thermal decompositions of Y, La and lanthanide (from Ce(III) to Lu(III) benzene-1,2-dioxyacetates with general formula Ln₂(C₁₀H₈O₆)₃·nH₂O were studied. The hydrated complexes first lose water of crystallization in one or two steps to yield anhydrous compounds or hydrates containing coordination water molecules, and then decompose to the oxides Ln₂O₃, CeO₂, Pr₆O₁₁ and Tb₄O₇ with formation of intermediates, carbonates and oxycarbonates (La, Pr-Eu), oxycarbonates (Y, Tb-Lu) or carbonate (Gd) only. Anhydrous cerium(III) benzene-1,2-dioxyacetate decomposes on heating directly to CeO₂.     

Structural Diversity of Infinite 3d–4f Heterometallic Cluster Compounds Driven by Various Lanthanide Radii

The syntheses, structures, and characterization of six Ln³⁺–Cu²⁺–glycine (Hgly) coordination polymers are described in this paper. They represent three types of structures. Type I (Ln=La ( 1 ), Pr ( 2 ), and Sm ( 3 )) is a 1D catenarian polymer comprising [Ln₂] nodes bridged by four cis‐Cu(gly)₂ linkers. Type II (Ln=Eu ( 4 ) and Dy ( 5 )) is a 2D open framework with a 4⁴‐net, composed of novel [Ln₆Cu₂₂] cluster nodes linked by trans‐Cu(gly)₂ linkers. Furthermore, the inner structures of the [Ln₆Cu₂₂] nodes, and the connection mode between the nodes and linkers are slightly different for 4 and 5 . Type III (Ln=Er ( 6 )) is a 3D open framework with a novel 3⁶?4¹⁸?5³?6 topology, made up of [Er₆Cu₂₄] cluster nodes and trans‐Cu(gly)₂ linkers. The rich variety of the resulting structures owes itself mainly to the interselection between the dynamic control of metalloligands and cationic components. A transition from frequency dependence to frequency independence is observed in the field‐induced magnetization lag for 1 – 3 . The frequency dependence at low temperatures may come from the antiferromagnetic Cu? Cu interaction through the [Ln₂] nodes, whereas the frequency independence may be due to the disappearance of the antiferromagnetic Cu? Cu interaction at high temperatures.     

1,2-萘醌-4-磺酸钠体系分光光度法测定头孢他啶

建立了用1,2-萘醌-4-磺酸钠(NQS)作为显色剂分光光度法测定头孢他啶(ceftazidime)的新方法.在pH 13.0缓冲溶液中,NQS能直接与头孢他啶发生亲核取代反应生成红褐色化合物,其最大吸收波长为484 nm.头孢他啶在2.98～127.3 mg/L浓度范围内与吸光度呈良好线性关系,线性回归方程A=0.0...     

Thermal Stability of 4-Chloro-3-Nitro- and 5-Chloro-2-Nitrobenzoates of Rare Earth Elements

The physico-chemical properties and thermal stabilities in air of rare earth element 4-chloro-3-nitrobenzoates and 5-chloro-2-nitrobenzoates were compared and the influence of the positions of the Cl and NO₂ substituents on their thermal stabilities was investigated. The complexes of both series are crystalline, hydrated or anhydrous salts with colours typical of Ln³⁺. The carboxylate group in these complexes is a bidentate, chelating ligand. The NO₂ group in the chloronitro complexes does not undergo isomerization. The thermal stabilities of the 4-chloro-3-nitrobenzoates of Y and the lanthanides were studied in the temperature range 273-1173 K, but those of the 5-chloro-2-nitrobenzoates of these elements were studied only at 273-523 K, because they decompose explosively above 523 K. The positions of the Cl and NO₂ substituents on the benzene ring influence the thermal properties of the complexes and their decomposition mechanisms. The different thermal stabilities of the complexes are connected with various inductive and mesomeric effects of the Cl and NO₂ substituents on the electron density in the benzene ring. This revised version was published online in July 2006 with corrections to the Cover Date.     

Catalysis reaction between sodium 1,2-naphthoquinone-4-sulfonate and hydroxyl ion using captopril as catalyzer and determination of captopril

A novel and simple spectrophotometric method for the determination of Captopril with sodium 1,2-naphthoquinone-4-sulfonate is established in this paper. The detailed reaction mechanism is proposed and discussed. It is based on the fact that captopril can catalyze the reaction between sodium 1,2-naphthoquinone-4-sulfonate and hydroxyl ion to form 2-hydroxy-1,4-naphthoquinone in buffer solution of pH 13.00. Beer's law is obeyed in a range of 0.64-80 μg mL⁻¹ at the maximal absorption wavelength of 442 nm. The equation of linear regression is A = 0.05815 + 0.00589C (μg mL⁻¹), with a linear regression correlation coefficient of 0.9981. The detection limit is 0.3 μg mL⁻¹, R.S.D. is 0.77% and the recovery rate is in range of 96.0-103.8%. Furthermore, the method has been validated and successfully applied to the determination of captopril in pharmaceutical samples.     

Michael additions with an enaminoester: Reaction of phenyl 4-chromone-3-sulfonate with methyl 3-amino-2-pentenoate

The novel benzoxathiinopyridines 5 and 8 and the hitherto unknown oxathiinobenzopyran 17 were synthesized by ring transformations of phenyl 4-chromone-3-sulfonate ( 1 ) with methyl 3-amino-2-pentenoate ( 2 ). The structures of 5, 8 and 17 were determined by spectroscopic methods and the reaction pathways for the formation of these compounds are discussed.     

Controlled Synthesis of Heterotrimetallic Single‐Chain Magnets from Anisotropic High‐Spin 3 d–4 f Nodes and Paramagnetic Spacers

By using the node‐and‐spacer approach in suitable solvents, four new heterotrimetallic 1D chain‐like compounds (that is, containing 3d–3d′–4f metal ions), {[Ni(L)Ln(NO₃)₂(H₂O)Fe(Tp*)(CN)₃] ? 2 CH₃CN ? CH₃OH}_n (H₂L=N,N′‐bis(3‐methoxysalicylidene)‐1,3‐diaminopropane, Tp*=hydridotris(3,5‐dimethylpyrazol‐1‐yl)borate; Ln=Gd ( 1 ), Dy ( 2 ), Tb ( 3 ), Nd ( 4 )), have been synthesized and structurally characterized. All of these compounds are made up of a neutral cyanide‐ and phenolate‐bridged heterotrimetallic chain, with a {? Fe? C?N? Ni(? O? Ln)? N?C? }_n repeat unit. Within these chains, each [(Tp*)Fe(CN)₃]^? entity binds to the Ni^II ion of the [Ni(L)Ln(NO₃)₂(H₂O)]⁺ motif through two of its three cyanide groups in a cis mode, whereas each [Ni(L)Ln(NO₃)₂(H₂O)]⁺ unit is linked to two [(Tp*)Fe(CN)₃]^? ions through the Ni^II ion in a trans mode. In the [Ni(L)Ln(NO₃)₂(H₂O)]⁺ unit, the Ni^II and Ln^III ions are bridged to one other through two phenolic oxygen atoms of the ligand (L). Compounds 1 – 4 are rare examples of 1D cyanide‐ and phenolate‐bridged 3d–3d′–4f helical chain compounds. As expected, strong ferromagnetic interactions are observed between neighboring Fe^III and Ni^II ions through a cyanide bridge and between neighboring Ni^II and Ln^III (except for Nd^III) ions through two phenolate bridges. Further magnetic studies show that all of these compounds exhibit single‐chain magnetic behavior. Compound 2 exhibits the highest effective energy barrier (58.2 K) for the reversal of magnetization in 3d/4d/5d–4f heterotrimetallic single‐chain magnets.     

Spectroscopic study on the interaction between sodium 9,10-anthraquinone-2-sulfonate and DNA

Sodium 9,10-anthraquinone-2-sulfonate (AQS) binds to the double helical DNA with a high affinity, as deduced from the absorption and fluorescence spectral data. The results of absorption spectra, KI quenching studies, competitive binding studies, and thermal denaturation experiments suggested the intercalative binding of AQS into DNA bases.     

Five Rare μ4‐O‐Centered Ln6 Clusters with Single‐Molecule Magnet Behavior for Dy6

Five hexanuclear lanthanide clusters of composition [Ln₆(μ₄‐O)₂(HCOO)₂L₄(HL′)₂(dmf)₂] [Ln=Dy ( 1 ), Er ( 2 ), Ho ( 3 ), Tb ( 4 ), Gd ( 5 ); H₂L=2‐{[2‐(hydroxymethyl)phenylimino]methyl}‐6‐methoxyphenol; H₃L′=3‐{[2‐(hydroxymethyl)phenylimino]methyl}benzene‐1,2‐diol; H₃L′ was derived in situ from the H₂L ligand] were prepared under solvothermal conditions. The [Ln₆] cores of 1 – 5 possess an unprecedented motif, namely, two tetrahedron Ln₄ units sharing an edge and two vertices. The six Ln^III ions of 1 – 5 are connected through two μ₄‐O anions. Magnetic susceptibility studies reveal that complex 1 exhibits frequency dependence of the alternating current susceptibility typical of single‐molecule magnets. Complex 1 possesses a relatively large energy barrier of 85 K among all of the reported Dy₆ single‐molecule magnets.     

Oligonuclear 3d–4f Complexes as Tectons in Designing Supramolecular Solid‐State Architectures: Impact of the Nature of Linkers on the Structural Diversity

Heteronuclear cationic complexes, [LCuLn]³⁺ and [(LCu)₂Ln]³⁺, were employed as nodes in designing high‐nuclearity complexes and coordination polymers with a rich variety of network topologies (L is the dianion of the Schiff base resulting from the 2:1 condensation of 3‐methoxysalycilaldehyde with 1,3‐propanediamine). Two families of linkers have been chosen: the first consists of exo‐dentate ligands bearing nitrogen‐donor atoms (bipyridine (bipy), dicyanamido (dca)), whereas the second consists of exo‐dentate ligands with oxygen‐donor atoms (anions derived from the acetylenedicarboxylic (H₂acdca), fumaric (H₂fum), trimesic (H₃trim), and oxalic (H₂ox) acids). The ligands belonging to the first family prefer copper(II ) ions, whereas the ligands from the second family interact preferentially with oxophilic rare‐earth cations. The following complexes have been obtained and crystallographically characterized: [LCu^II(OH₂)Gd^III(NO₃)₃] ( 1 ), [{LCu^IIGd^III(NO₃)₃}₂(μ‐4,4′‐bipy)] ( 2 ), [LCu^IIGd^III(acdca)_1.5(H₂O)₂] ? 13 H₂O ( 3 ), [LCu^IIGd^III(fum)_1.5(H₂O)₂] ? 4 H₂O ? C₂H₅OH ( 4 ), [LCu^IISm^III(H₂O)(Hfum)(fum)] ( 5 ), [LCu^IIEr^III(H₂O)₂(fum)]NO₃ ? 3 H₂O ( 6 ), [LCu^IISm^III(fum)_1.5(H₂O)₂] ? 4 H₂O ? C₂H₅OH ( 7 ), [{(LCu^II)₂Sm^III}₂fum₂](OH)₂ ( 8 ), [LCu^IIGd^III(trim)(H₂O)₂] ? H₂O ( 9 ), [{(LCu^II)₂Pr^III}(C₂O₄)_0.5(dca)]dca ? 2 H₂O ( 10 ), [LCu^IIGd^III(ox)(H₂O)₃][Cr^III(2,2′‐bipy)(ox)₂] ? 9 H₂O ( 11 ), and [LCuGd(H₂O)₄{Cr(CN)₆}] ? 3 H₂O ( 12 ). Compound 1 is representative of the whole family of binuclear Cu^II–Ln^III complexes which have been used as precursors in constructing heteropolymetallic complexes. The rich variety of the resulting structures is due to several factors: 1) the nature of the donor atoms of the linkers, 2) the preference of the copper(II ) ion for nitrogen atoms, 3) the oxophilicity of the lanthanides, 4) the degree of deprotonation of the polycarboxylic acids, 5) the various connectivity modes exhibited by the carboxylato groups, and 6) the stoichiometry of the final products, that is, the Cu^II/Ln^III/linker molar ratio. A unique cluster formed by 24 water molecules was found in crystal 11 . In compounds 2 , 3 , 4 , 9 , and 11 the Cu^II–Gd^III exchange interaction was found to be ferromagnetic, with J values in the range of 3.53–8.96 cm^?1. Compound 12 represents a new example of a polynuclear complex containing three different paramagnetic ions. The intranode Cu^II–Gd^III ferromagnetic interaction is overwhelmed by the antiferromagnetic interactions occurring between the cyanobridged Gd^III and Cr^III ions.     

Correlations between electrochemical and spectral properties of alkyl-substituted diphthalocyanine lanthanide complexes

The electrochemical behavior and spectral properties of a series of symmetrical 2,3,9,10,16,17,23,24,2’,3’,9’, 10’,16’,17’,23’,24’-hexadecaalkyl-substituted lanthanide complexes (R₈Pc)₂Ln (R = H, Me, Et, Buⁿ; Ln = Eu, Dy, Lu) were studied. Regularities of changing the parameters under study were established, depending on the nature of lanthanide and substituents in the phthalocyanine macroligands. The position of the intervalence band of the complexes in the near-IR region depends on the effective distance between the macroligands and also on the electronic effect of the substituents. Correlations between the electrochemical and spectral properties of the complexes were found.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 184–189, January, 2005.     

Study of methanol catalyzed reaction between sodium 1,2-naphthoquine-4-sulfonate and hydroxyl ion and its application in the determination of methanol

A novel and simple spectrophotometric method for the direct determination of methanol with 1,2-naphthoquinone-4-sulfonate (NQS) is developed in this paper. It is based on the fact that methanol can catalyze the reaction between 1,2-naphthoquinone-4-sulfonate and hydroxyl ion to form 2-hydroxy-1,4-naphthoquinone in buffer solution of pH 13.00. Beer's law is obeyed in a range of 0.26-15.8 mg/ml at the maximal absorption wavelength of 454 nm. The equation of linear regression is A = 0.01998 + 0.05944C (mg/ml), with a linear regression correlation coefficient of 0.9977. The detection limit is 0.25mg/ml (3sigma/k), while R.S.D. is 2.0% and the recovery rate is in a range of 96.5-103%. The detailed mechanism for the formation of the products is proposed and discussed.     

1, 2-萘醌-4-磺酸钠分光光度法测定间苯二酚

在pH 13.00缓冲溶液中, 间苯二酚能够催化氢氧根离子与1,2-萘醌-4-磺酸钠反应生成2-羟基-1, 4-萘醌, 其最大吸收波长为454 nm. 间苯二酚质量浓度在0.39～13.21 mg/L范围内与吸光度呈现良好线性关系. 线性回归方程为A=0.01918+0.05703c (×105 mol/L), 相关系数r=0.9981. RSD和检测限分别为1.6%, 0.34 mg/L (3σ/k). 该法能够直接用于水样中间苯二酚含量测定, 回收率在94.3%～106%.     

1，2-萘醌-4-磺酸钠分光光度法测定链霉素的研究

链霉素(streptomycin,STR)是一种对结核分枝杆菌有强大抗菌作用的氨基糖苷类抗生素,它通过作用于细胞的核糖体抑制细菌蛋白质的生物合成而呈现杀菌作用[1].目前所报道检测链霉素含量的方法主要有高效液相色谱法[2] 、鲁米诺的流动注射化学发光法[3] 、微生物学检测法[4、5] 、荧光法[6]、免疫法[7]以及紫外分光度度法[8]等,但以可见光度法测定链霉素的研究还很少有报道.本文基于1,2-萘醌-4-磺酸钠(NQS)能与含有胺基类药物分子结构中的胺基发生亲核缩合或取代作用 [9-13],建立了以NQS作为显色剂在可见光度法测定STR的新方法.研究表明,控制溶液pH12.00,STR与NQS发生缩合反应生成摩尔比为1: 2红褐色产物,最大吸收波长λ max =470 nm,STR浓度在2.91μg/mL～145.7μg/mL范围内与吸光度成良好线性关系.与文献中所报道的其他方法相比,该方法不仅具有简便、快速、不需昂贵的仪器设备等特点,具有重要的应用价值.     

Magnetocaloric Properties of Heterometallic 3d–Gd Complexes Based on the [Gd(oda)3]3− Metalloligand

A series of heterometallic 3d–Gd³⁺ complexes based on a lanthanide metalloligand, [M(H₂O)₆][Gd(oda)₃] ? 3 H₂O [M=Cr³⁺ ( 1‐Cr )] (H₂oda=2,2′‐oxydiacetic acid), [M(H₂O)₆][MGd(oda)₃]₂ ? 3 H₂O [M=Mn²⁺ ( 2‐Mn ), Fe²⁺ ( 2‐Fe ) and Co²⁺ ( 2‐Co )], and [M₃Gd₂(oda)₆(H₂O)₆] ? 12 H₂O [M=Ni²⁺ ( 3‐Ni ), Cu²⁺ ( 3‐Cu ), and Zn²⁺ ( 3‐Zn )], are reported. Magnetic and heat‐capacity studies revealed a significant impact on the magnetocaloric effect depending on the anisotropy of the 3d transition metal ions, as confirmed by comparison of the observed maximum values of ?ΔS_m between complexes 2‐Co and 1‐Cr . In these two complexes, the 3d metal ions have the same spin (S=3/2 for Co²⁺ and Cr³⁺ ions), and the theoretical calculation suggested a larger ?ΔS_m value for 2‐Co (47.8 J K^?1 kg^?1) than 1‐Cr (37.5 J K^?1 kg^?1); however, the significant anisotropy of Co²⁺ ions in 2‐Co , which can result in smaller effective spins, gives a smaller value of ?ΔS_m for 2‐Co (32.2 J K^?1 kg^?1) than for 1‐Cr (35.4 J K^?1 kg^?1) at ΔH=9 T.     

Activation of SO2 with [(η5‐C5Me5)2Ln(THF)2] (Ln=Eu,Yb) Leading to Dithionite and Sulfinate Complexes

The reaction of decamethylytterbocene [(η⁵‐C₅Me₅)₂Yb(THF)₂] with SO₂ at low temperature gave two new compounds, namely, the Yb^III dithionite/sulfinate complex [{(η⁵‐C₅Me₅)₂Yb(μ₃,1κ²O^1,3,2κ³O^2,2′,4‐S₂O₄)}₂{(η⁵‐C₅Me₅)Yb(μ,1κO,2κO′‐C₅Me₅SO₂)}₂] ( 1 ) and the Yb^III dithionite complex [{(η⁵‐C₅Me₅)₂Yb}₂(μ,1κ²O^1,3,2κ²O^2,4‐S₂O₄)] ( 2 ). After extraction of 1 , the mixture was heated to give the dinuclear tetrasulfinate complex [{(η⁵‐C₅Me₅)Yb}₂(μ,κO,κO’‐C₅Me₅SO₂)₄] ( 3 a ). In contrast, from the reaction of [(η⁵‐C₅Me₅)₂Eu(THF)₂] with SO₂ only the tetrasulfinate complex [{(η⁵‐C₅Me₅)Eu}₂(μ,κO,κO’‐C₅Me₅SO₂)₄] ( 3 b ) was isolated. Two major reaction pathways were observed: 1) reductive coupling of two SO₂ molecules to form the dithionite anion S₂O₄^2?; and 2) nucleophilic attack of one metallocene C₅Me₅ ligand on the sulfur atom of SO₂. The compounds presented are the first dithionite and sulfinate complexes of the f‐elements.