Metal complexes of sterically hindered pyrzolylpyridines. The single crystal X-ray structure of [Cu(L)2]BF4 (L = 1-{pyrid-2-yl}-3-{2′,5′-dimethoxyphenyl}pyrazole)

Reaction of potassium 3{5}-(3′,4′-dimethoxyphenyl)pyrazolide with 2-bromopyridine in diglyme at 130°C for 3 days followed by an aqueous quench, affords 1-{pyrid-2-yl}-3-{3′,4′-dimethoxyphenyl}pyrazole (L²) in 69% yield after recrystallization from hot hexanes. Complexation of [Cu(NCMe)₄]BF₄ by 2 molar equivalents of 1-{pyrid-2-yl}-3-{2′,5′-dimethoxyphenyl}pyrazole (L¹) or L² in MeCN at room temperature, followed by concentration and crystallisation with Et₂O, gives [Cu(L)₂]BF₄ L = L¹, L²) in good yields. Treatment of AgBF₄ with L¹ or L² in MeNO₂ similarly gives [Ag(L)₂]BF₄ L = L¹, L²); reaction of AfBF₄ with L² in MeCN gives a product of stoichiometry [Ag(L²)(NCMe)]BF₄. The ¹H NMR spectra of the [M(L)₂]BF₄ complexes show peaks arising from a single coordinated environment. The single crystal X-ray structure of [Cu(L¹)₂]BF₄ shows a tetrahedral complex cation with Cu---N = 2.011(8), 2.036(8), 2.039(8), 2.110(8) Å. The Cu^I centre is close to tetrahedral, the dihedral angle between the least-squares planes formed by the Cu atom and the N donor atoms of the two ligands being 88.3(3)°. Complexation of hydrated Cu(BF₄)₂ by L² in MeCN at room temperature yields [Cu(L₂)₂](BF₄)₂. The cyclic voltammograms of the three Ag^I complexes in MeCN/0.1 M Bu₄ⁿ NPF₆ are suggestive of extensive ligand dissociation in this solvent.     

2-(Phenyltelluromethyl)tetrahydrofuran (L) and 2-(2-{4-methoxyphenyl}telluroethyl)-1,3- dioxolane (L) and their palladium(II) and platinum(II) complexes

The nucleophile [ArTe⁻] generated in situ borohydride solution of Ar₂Te₂, reacts with 2-(chloromethyl) tetrahydrofuran and 2-(2-bromoethyl)-1,3-dioxolane resulting in L¹ and L², respectively. The complexes of palladium(II) and platinum(II) with L¹/L² having stoichiometries [MCl₂·L₂], [ML₂](ClO₄)₂, [(DPPE)ML₂](ClO)₄)₂, [(PPh₃)₂ML₂](ClO₄)₂ and [(phen)ML₂](ClO₄)₂ (where L = L¹/L² DPPE = Ph₂PC H₂CH₂PPh₂, PHEN = 1,10-phenanthroline and M = Pd/Pt) have been synthesized. IR, ¹H, ¹²⁵Te{¹H} and ³¹P{¹H} NMR and UV-vis spectral data of these species in conjunction with their molar conductance and molecular weight data have been used to authenticate the new species. In all complexes (1–20) the ligands L¹ and L² are coordinated through tellurium and in the complexes of formula [ML₂](ClO₄)₂ (M = Pd, Pt) the ligand is bidentate with the oxygen atom used in complexation. In solution, complexes PtCl₂L₂ exist as a mixture of cis and trans isomers whereas only the trans isomer was observed for the palladium analogues. The [(phen)PdL₂](ClO₄)₂(Q) quenches ¹O₂ readily. The plot of log [Q] vs time is linear. Mechanism compatible with the experimental observations is proposed.     

The preparation and coordination chemistry of 2,2′:6′,2″-terpyridine macrocycles—VI. Planar hexadentate macrocycles incorporating 2,2′: 6′,2″-terpyridine

The template condensation of 6,6″-bis(-methylhydrazino)-2,2′: 6′,2″-terpyridines L² and L³ with 2,6-pyridinedialdehyde may give a number of different products depending upon the metal ion which is used. In the presence of nickel(II) the products are either the nickel(II) complexes of the 18-membered ring macrocycles L⁴ or L⁵ or the free macrocycles. The metal ion acts as a transient template and is removed in a chloride ion specific demetallation. The use of dimethyltin(IV) as a template results in the formation of complexes of the ring contracted macrocycles L⁶ or L⁷.     

Acide 2-fluoro-2-phényl propanoïque: préparation et utilisation comme agent chiral de dérivation

The enantiomers of 2-fluoro-2-phenyl propanoic acid have been separated and theirabsolute configurations determined: the specific rotation of the acid with an R configurationis []²⁰_D= −28.5° (c = 1.5, ethanol). This acid has been used as a chiral derivatizingagent. Esters and amides prepared from this acid and chiral alcohols or amines presentimportant fluorine chemical shift differences between the diastereoisomers     

M(CO)4 (M = Mo or W) complexes of 2,6-bis(methylthiomethyl)pyridine (L) and 2,6-bis(p-tolylthiomethyl)pyridine (L): a dynamic NMR study

The hybrid S/N/S donor ligands 2,6-bis(methylthiomethyl)pyridine (L¹) and 2,6-bis(p-tolylthiomethyl)pyridine (L²) react with the [M(CO)₅(THF)] (M = Mo or W) compounds to form complexes of general formula [M(CO)₄L] (M = Mo, L = L²; M = W, L = L¹ or L²), where both L¹ and L² act in a S/N bidentate chelate fashion. In solution, these complexes undergo three fluxional processes, viz. inversion at the coordinated S atom, S¹–S² switching, and combined inversion and S¹–S² switching, leading to an interconversion of the four possible permutational isomers. Energy barriers for all three processes have been evaluated by standard one-dimensional band-shape analysis techniques. The mechanism of the S¹–S² switch is discussed.     

Organosilicon backbone containing pyridyl/quinolyl ligands: Synthesis, complexation reactions and single crystal structures of metallamacrocyclic Pd(II) and Cu(II) complexes

Organosilicon backbone containing ligands 1,2-bis(dimethyl(2-pyridyl)silyl)ethane (L¹) and 1,2-bis(dimethyl(3-quinolyl)silyl) ethane (L²) have been synthesized by treating 2-bromopyridine and 3-bromoquinoline with n-butyllithium and reacting the resulting lithiated products with 1,2-bis(chlorodimethylsilyl)ethane. The ligation of L¹ and L² with Pd(II), Ag(I) and Cu(II) has been investigated. The single crystal structures of L², [Pd(L¹)Cl₂] (1), [Cu(L¹)Br₂] (3) and [PdCl₂(L²)]₂ (4) have been solved. All the three complexes are metallamacrocyclic in nature. The last one is 22-membered and the first example which has ligands containing organosilicon backbone. The geometry of Pd as well as Cu is very close to square planar. The Pd–N, Pd–Cl, Cu–N and Cu–Br bond distances (2.010(1)–2.027(3), 2.3063(10)–2.3114(4), 2.004(4)–2.018(5) and 2.4137(10)–2.4172(10) Å) are very close to sum of covalent radii, indicating strong ligation of L¹ and L² with the metal ions.     

Chirality induction of π-conjugated chains through chiral complexation

Chirality induction of π-conjugated polyanilines through chiral complexation with the chiral palladium(II) complexes was demonstrated to afford the chiral conjugated polymer complexes. Complexation of the emeraldine base of poly(o-toluidine) (POT) with the chiral palladium(II) complex bearing one labile coordination site led to the formation of the chiral conjugated polymer complex, which exhibited an induced circular dichroism (ICD) based on the chirality induction into a π-conjugated backbone. The mirror image of the CD signal was observed with the chiral conjugated polymer complex, which was obtained from the chiral palladium(II) complex possessing the opposite configuration. The chirality of the podand ligand moieties of the palladium complex is considered to induce a propeller twist of the π-conjugated molecular backbone. The crystal structure of the chiral conjugated complex of N-bis(4′-dimethylaminophenyl)-1,4-benzoquinonediimine (L³) as a model compound of the polyaniline revealed a chiral propeller twist conformation of the π-conjugated backbone. Furthermore, chiral complexation with the cationic palladium(II) complexes provided the ionic chiral conjugated complexes.     

Synthesis, crystal structure and characterization of ternary complexes of lanthanide(III) 3,5-di-tert-butyl-γ-resorcylate with substituted pyridine-N-oxide

Twenty one ternary complexes of lanthanide with 3,5-di-tert-butyl-γ-resorcylic acid (L) and seven different substituted pyridine-N-oxides (L^1–7), with compositions of REL₃L^1–7₂·nH₂O (RE=Nd, Gd, Er; L¹=4-picoline-N-oxide; L²=4-phenyl-pyridine-N-oxide; L³=pyridine-N-oxide; L⁴=3-picoline-N-oxide; L⁵=quinoline-N-oxide; L⁶=iso-quinoline-N-oxide; L⁷=4-methoxyl-pyridine-N-oxide; n=0, 1, 2, 5), were synthesized and characterized by means of elemental analysis, electrical conductivity, thermal analysis and IR spectra. The novel crystal structure of ErL₃L³₂·(EtOH) has been determined by a single-crystal X-ray diffraction method. It shows that each erbium ion is linked to three 3,5-di-tert-butyl-γ-resorcylic acid ions through two different types of dentation modes in which only the carboxylate oxygen atoms participate. The coordination geometries of erbium ion can be described as a distorted octa-coordinated bicapped trigonal prism.     

氮氧杂链型配体合成与Cu(Ⅱ)和Zn(Ⅱ)配位性质研究

合成了4种氮氧杂链型配体N,N'-二-(2-羟乙基)-乙二胺(L¹)、N-(2-羟基苄基)-丙醇胺(HL²)、N-(2-羟乙基)-N'-(2-羟基苄基)-乙二胺(HL³)和N-(2-羟乙基)-二乙三胺-(L⁴),通过元素分析、IR和¹H NMR等手段表征了其结构,用pH电位滴定法在25℃、I=0.10(KNO₃)条件下,测定了L¹和HL²与Cu(Ⅱ)离子以及HL³和L⁴与Zn(Ⅱ)离子配位平衡常数.结果表明:L¹和HL²与Cu(Ⅱ)离子配位时,均可生成四配位配合物,其中第三配位点醇羟基配位较强,其质子离解常数pK_a1分别为7.28和7.32;第四配位点是第2个醇羟基或1个水分子配位,其pK_a2分别为9.33和9.04;HL³和L⁴与Zn(Ⅱ)均可生成五配位配合物,第四配位点均为醇羟基,其离解常数pK_a1分别为7.76和7.96,第五配位点均为H₂O,其pK_a2分别为9.47和9.57.从上述热力学结果可见,配合物在中性pH值范围能生成亲核试剂Cu(Ⅱ)…^-OR或Zn(Ⅱ)…^-OR,而且均具备双重催化酯类底物水解的条件.     

钴(Ⅱ)Schiff碱螯合物及其氧加合物的合成与表征

合成了一种新的四齿Schiff碱配体N,N-亚乙基-双(1-乙酰萘酚-2(L²),两种新的钴(Ⅱ)螯合物CoL²和CoL³·H₂O(L³=N,N-亚苯基(1-苯基-3-甲基-4-苯甲酰基吡唑啉酮-5)及两种新的1:1氧加合物CoL¹·Py·O₂·2H₂O(L¹=N,N-亚乙基-双(1-苯基-3-甲基-4-苯甲酰基吡唑啉酮-5)和CoL²·Py·O₂·2H₂O。用元素分析、IR、UV、ESR、¹HNMR、MS、TGA、磁矩和电导测定进行了表征。     

Synthese et etude par resonance magnetique nucleaire du carbone 13 et de l'etain 119 d'une serie de triorganostannyl-2 butanes

Optically active triorgano-2-stannylbutanes have been synthetized by different methods, one being the direct substitution of optically active s-butyl halides with triorganostannyl alkali metals. This route involves a complete or partial inversion of configuration at the chiral carbon atom. Carbon-13 and tin-119 NMR data are reported as support for the identification of eight triorgano-2-stannylbutanes. The special case of tetra(2-butyl)tin, with four identical chiral centres has been examined.     

Diastereoselective preparation of (R)- and (S)-2-methoxy-2-phenylpent-3-ynoic acids and their use as reliable chiral derivatizing agents

Benzoyl-S,O-acetals 1a and 1b were used as chiral auxiliaries to achieve the diastereoselective preparation of both enantiomers of 2-methoxy-2-phenylpent-3-ynoic acids (MPPAs). The latter were condensed with several chiral secondary alcohols and some primary amines to evaluate their potential as chiral derivatizing agents (CDAs). The (1)H NMR spectra of the corresponding esters and amides showed strong consistency with the absolute configuration of the carbinol and amine moieties, whose observed ΔδL(1) and ΔδL(2) values were in the ranges of 0.1-0.4 and 0.02-0.12 ppm, respectively.     

Zn(II) complexes with pyridine derived N6 and N8 donor azamacrocyclic ligands

A novel N6 macrocyclic ligand, L¹ (2,8,14,20-tetramethyl-3,7,15,19,25,26-hexaaza-tricyclo[19.3.1.1^9,13]hexacosa-1(24),9,11,13(26),21(25),22-hexaene), was obtained by reduction of the 2 + 2 condensation product of 2,6-diacetylpyridine and propane-1,3-diamine. Zinc(II) complexes of L¹, of a related N8 macrocycle, L³ (3,6,9,17,20,23,29,30-octaaza-tricyclo[23.3.1.1[11,15]]triaconta-1(28),1,13,15(30),25(29),26-hexaene), similarly prepared by 2 + 2 condensation of 2,6-diformylpyridine and diethylenetriamine and of a tetra N-2-cyanoethyl derivative of a homologue of L¹ prepared from diformyl pyridine and ethane-1,2-diamine, L² (3-[6,14,17-tris-(2-cyano-ethyl)-3,6,14,17,23,24-hexaaza-tricyclo[17.3.1.1^8,12] tetracosa-1(23),8(24),9,11,19,21-hexaen-3-yl]-propionitrile), were prepared. Structures were determined for [ZnL¹](ClO₄)₂ · H₂O, [ZnL²](NO₃)₂ and [Zn₂L³(NO₃)₂](NO₃)₂ · H₂O. The [ZnL¹](ClO₄)₂ · H₂O and [ZnL²](NO₃)₂ complexes present a mononuclear endomacrocyclic structure with the metal in an octahedral distorted environment coordinated by the six donor nitrogen atoms from the macrocyclic backbone while the complex [Zn₂L³(NO₃)₂](NO₃)₂ · H₂O is dinuclear with both metal atoms into the macrocyclic cavity coordinated by four donor nitrogen atoms from the macrocyclic framework and one oxygen atom from one monodentate nitrate anion, in a distorted square pyramidal arrangement.     

Structural and spectral investigation on the Co complexes with 1,4-diazacycloheptane (DACH) functionalized by heterocyclic pendants

A series of penta-coordinated Co^II complexes of 1,4-diazacycloheptane (DACH) functionalized by additional imidazole or pyridine donor pendants, [CoL¹Cl](ClO₄)·H₂O (1), [CoL²Cl](ClO₄) (2) and [CoL³Cl](ClO₄)·CH₃OH (3), where L¹=1,4-bis(imidazole-4-ylmethyl)-DACH, L²=1,4-bis(N-1-methylimidazol-2-ylmethyl)-DACH and L³=1,4-bis(pyridyl-2-ylmethyl)-DACH have been synthesized and characterized by elemental analyses, IR and UV–Vis spectra. In all the mononuclear complexes, each Co^II center is penta-coordinated to four nitrogen donors of the ligand and one axial chloride anion. The crystal structure of complex 2 has been determined by X-ray diffraction analysis, which forms a one-dimensional linear structure through inter-molecular C–HCl and C–HO hydrogen-bonding.     

Synthesis, structure and nuclease activity of copper complexes of disubstituted 2,2′-bipyridine ligands bearing ammonium groups

A series of Cu(II) complexes of disubstituted 2,2′-bipyridine bearing ammonium groups [Cu(L¹⁻⁴)₂Br]⁵⁺ (1–4, L¹ = [5,5′-(Me₂NHCH₂)₂-bpy]²⁺, L² = [5,5′-(Me₃NCH₂)₂-bpy]²⁺, L³ = [4,4′-(Me₂NHCH₂)₂-bpy]²⁺, L⁴ = [4,4′-(Me₃NCH₂)₂-bpy]²⁺ and bpy = 2,2′-bipyridyl) were synthesized, of which complexes 1 and 4 were structurally characterized. Both coordination configurations of Cu(II) ions can be described as distorted trigonal bipyramid. The interaction between all complexes and CT-DNA was evaluated by thermal-denaturation experiments and CD spectroscopy. Results show that the complexes interact with CT-DNA via outside electrostatic interactions and their binding ability follows the order: 1 > 2 > 3 > 4. In the absence of any reducing agents, the cleavage of plasmid pBR322 DNA by these complexes was investigated and the hydrolysis kinetics of DNA was studied in Tris buffer (pH 7.5) at 37 °C. Obtained pseudo-Michaelis–Menten kinetic parameters: 15.0, 13.6, 2.01 and 1.69 h⁻¹ for 1, 2, 3 and 4, respectively, indicate that complexes 1 and 2 exhibit very high DNA cleavage activities. According to their crystal data, the high nuclease activity may be attributed to the strong interaction of the metal moiety and two ammonium groups with phosphate groups of DNA.     

Determination of pK(a)'s for thymol blue in aqueous medium: evidence of dimer formation

Formation constants for recrystallized thymol blue were determined in water, using the SQUAD and SUPERQUAD programs. The best model correlating spectrophotometric, potentiometric and conductimetric data was fitted with the dissociation of HL⁻=L²⁻+H⁺−log K=8.918±0.070 and H₃L₂⁻=2L²⁻+3H⁺−log K=29.806±0.133 with the SUPERQUAD program at variable low ionic strength (1.5×10⁻⁴–3.0×10⁻⁴ M); and HL=L²⁻+H⁺−log K=8.9±0.000, H₃L₂⁻ =2L²⁻+3H⁺−log K=30.730±0.032, H₄L₂=2L²⁻+4H⁺−log K=32.106±0.033 with SQUAD at 1.1 M ionic strength.     

Syntheses of three terbium complexes as fluorescent probes and their application on the pH detection of routine urine test

By modifying the salicylic-acid moiety with electron-withdrawing or –donating groups, three new terbium complexes(L~Ⅰ·Tb, L~(Ⅱ)·Tb, L·~(Ⅲ)Tb) based on tripodal carboxylate ligands were synthesized. Due to different pull-push electronic effects of ligands, the fluorescence intensities of these terbium complexes significantly varied, that is: L~(Ⅱ)·Tb L~(Ⅲ)·Tb L~Ⅰ·Tb. Meanwhile, the characteristic peaks at 492 nm(~5D_4→~7F_6) and 547 nm(~5 D_4→~7F_5) showed "Off–On–Off" fluorescence response to various p H conditions,which indicated that all of them can be used as the highly sensitive pH fluorescent probes. Notably, using L~(Ⅱ)·Tb with the best fluorescence performance as a probe, some patients' urine samples can be easily monitored through the response triggered by pH value. Therefore, L~(Ⅱ)·Tb has the potential to auxiliarily diagnose some diseases in clinical practice through p H detection of routine urine test.     

金属离子与卟啉的嵌入反应动力学研究(Ⅳ)──乳酸缓冲体系中四吡啶基卟啉衍生物与铜(Ⅱ)的配位反应

研究了在35±0.1℃、离子强度0.5mol/L(KCI)下,乳酸根催化Cu²⁺离子嵌入溴化间-四(N-乙酸甲酯基-3-吡啶基)卟啉和溴化间-四(N-氰乙基-3-吡啶基)卟啉的反应动力学。根据催化剂浓度、溶液的pH值与反应速率间的关系,得到Cu²⁺离子嵌入该类卟啉的反应动力学方程。实验结果表明,该类反应遵循负离子催化卟啉变形机理,变形的卟啉及其与乳酸根离子的缔合物为可能的活性中间体。     

A novel generation of coupling reagents. Enantiodifferentiating coupling reagents prepared in situ from 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) and chiral tertiary amines

Coupling of racemic N-protected amino acids with amino components by means of 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) in the presence of chiral tertiary amines such as strychnine, brucine, and sparteine proceeds enantioselectively, affording appropriate amides or dipeptides in 69-85% yield. The configuration of the preferred enantiomer and enantiomeric enrichment depend on the structures of the amine and carboxylic acid. Calculated Kagan enantioselectivity parameters (s) are in the range 1.6-195. Chiral triazinylammonium chlorides formed in situ from CDMT and chiral tertiary amines are postulated as reactive intermediates involved in the process of enantioselective activation of N-protected amino acids.     

Four Coordination Polymers Assembled with a New Biscarboxyl-functionalized Schiff Base Ligand

Based on a new biscarboxyl-functionalized Schiff base ligand 1,2-cyclohexanediamino-N,N'-bis[3-methoxyl-5-(p-carboxyl-phenylazo)] salicylidene(H₄L), four polymers,[(CH₃)₂NH₂]₂·[Mn₃(L)₂(H₂O)₄]·2DMF(CP1),[Fe₂(L)(H₂O)(DMF)](CP2),[(CH₃)₂NH₂]·[Cu(HL)]·H₂O(CP3) and[Ni₂(L)(teta)]·2DMF·H₂O(CP4), have been synthesized(teta=5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). In CP1, both of the internal[N₂O₂] pocket and the external carboxylate groups of L^4- anion are ligated by Mn²⁺ ions, and the structure displays a layer. In CP2, the Fe²⁺ cations are linked by L^4- anions to form a binuclear double chain. CP3 displays a[Cu₂(HL)₂] dimer. In CP4, the Ni²⁺ ions are connected by L^4- anions to form a chain. The structures are further linked by hydrogen bonds to form 2D or 3D supramolecular architectures, respectively. CP1 exhibits adsorption ability to three organic dyes.