Assembly,crystal structures,and luminescent properties of three new thiocyanate-bridging mercury(II) coordination polymers

Two ligands, 2-{5,5-dimethyl-3-[2-(pyridin-3-yl)-ethenyl]cyclohex-2-enylidene}propanedinitrile (L1) and 2-{5,5-dimethyl-3-[2-(pyridin-2-yl)-ethenyl]cyclohex-2-enylidene}propanedinitrile (L2), were synthesized. By reaction of mercury thiocyanate with L1 and L2, respectively, coordination polymers [Hg(L1)(μ_1,3-SCN)₂]_n (1), [Hg(L1)₂(μ_1,3-SCN)₂]_n (2), and [Hg(L2)(μ_1,3-SCN)(SCN)]_n (3) with different structures and topologies were obtained. In 1, the thiocyanate shows μ_1,3-SCN bridging coordination, and adjacent Hg(II) ions are bridged by two μ_1,3-SCN ions to form an infinite chain with the remaining position of five-coordinate Hg(II) occupied by L1. In 2, the thiocyanate has the same coordination as 1. However, Hg(II) has octahedral coordination with two L1 involved in coordination. An unusual feature of 3 is the presence of two types of thiocyanates, one has a S-terminal ligand and the other has a μ_1,3-SCN bridge. The mercury(II) in 3 is four-coordinated by L2 and three thiocyanates. Luminescent properties and thermal stabilities of 1–3 were studied.     

Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)2CuX2 and (3,5-FCAPH)2CuX4

Using 2-amino-5-chloro-3-fluoropyridine, two new copper halide coordination complexes and two new salts have been synthesized: [(3,5-FCAP)₂CuCl₂] (1), [(3,5-FCAP)₂CuBr₂](2), (3,5-FCAPH)₂[CuCl₄] (3) and (3,5-FCAPH)₂[CuBr₄] (4) [3,5-FCAP?=?2-amino-5-chloro-3-fluoropyridine; 3,5-FCAPH?=?2-amino-5-chloro-3-fluoropyridinium]. These complexes have been analyzed through single-crystal X-ray diffraction and temperature-dependent magnetic susceptibility. Compounds 1 and 2 crystallize in the triclinic space group P-1, while 3 and 4 crystallize in the monoclinic space group P2₁/c. All structures were distinct, with 1 giving a bihalide bridged chain, 2 yielding a halide bridged dimer, 3 forming a two-halide bridged chain via short Cl???Cl contacts, and 4 producing a rectangular sheet via short Br???Br contacts. All four compounds exhibit anti-ferromagnetic interactions and were fit to linear chain (1 and 3), dimer (2), and rectangular 2-D sheet (4) models. The resulting J/k_B values are ?3.4(1), ?31.3(8), ?0.9(1), and ?9.46(6)?K with an α value (α?=?J?/J) of 0.06(2), respectively.     

Synthesis and Characterization of Alkyltris(2-pyridyl)phosphonium Salts

Alkytris(2-pyridyl)phosphonium salts [(2-Py) ₃ PR]X 1 [1a, R = Et, X = Br; 1b, R = Pr, X = Br; 1c, R = Bu, X = Br; 1d, R = CH₂Ph, X = Br; 1e, R = CH ₂ Ph, X = Cl] were synthesised from (2-Py) ₃ P and an excess of RCl. 1c and 1e were found to rapidly decompose in hot acetone to 2,2′-bipyridinium(+1) bromide 2 and (2-Py)P(O)(CH ₂ Ph)C(OH)Me ₂ 3, respectively. A reaction mechanism for both products is proposed. All compounds were fully characterized, including X-ray crystallography for 1a and 3 with 1a being the first representative of this class of compounds characterized by this technique.     

From Planar Toward Tetrahedral Copper(Il) Complexes: Structural and Electron Paramagnetic Resonance Studies of Substituent Steric Effects in an Extended Class of Pyrrolate-Imine Ligands

A series (1a-1h) of crystalline bis-pyrrolate-imine copper(II) complexes was isolated in good yield (typically 60-90%) by reaction of the Schiff base 2-N-(R)-pyrrolecarbaldimine (where R is an alkyl group of variable steric capacity) with a copper(II) salt and base in methanol or water. For new complexes 1f-1h, pyrrolate-imine coordination is inferred by loss of ν(N-H) and a shift (ca. 40 cm^?1) to lower energy for ν(C=N) in the infrared spectra relative to free Schiff base. The X-ray crystal structures of 1f, where R = benzyl, and 1g, where R = diphenylmethyl, show trans geometry of the pyrrolate-imine moieties around Cu(II). The distortion from planarity of the CuN₄ coordination sphere, defined as the dihedral angle between the two chelating N(imine)-Cu-N(pyrrolate) planes, is 33.13(5)° for 1f and 29.3° for 1g. X-band electron paramagnetic resonance (EPR) spectra for 1a-1h in glassy solutions (ca. 100 K) are approximately axial, with an inverse correlation between A _z and g _z . At room temperature in fluid solution there is an inverse correlation between A _iso and g _iso. Plots of A _z , A _iso, g _z , or g _iso as a function of the dihedral angles between the ligand planes in 1f and 1g, as well as the previously characterized 1a (R = H) and 1d (R = tert-butyl) were used to determine the dihedral angles of the four complexes of unknown geometry. A red-shift in the ligand field bands in the electronic absorption spectra in chloroform also correlates with increasing dihedral angle. For each of these correlations, the data point for the diphenylmethyl derivative 1g deviates slightly from the line based on the other complexes; this is attributed to crystal packing forces causing a smaller dihedral angle for 1g in the crystal than in solution.     

Crystal structures and fluorescence properties of two architecture-correlated Zn(II)/Cd(II) MOFs constructed from an unprecedented tri-triazole ligand

By employing an unprecedented tri-triazole ligand, 4-amino-3,5-bis-(1H-1,2,4-triazole)-1,2,4-triazole (H₂L), two Zn(II)/Cd(II) metal-organic frameworks (MOFs), [ZnL]·3H₂O (1) and [CdL]·H₂O (2), were successfully synthesized and characterized. In the two complexes, M(II) centers are chelated and bridged by L bridges to form a one-dimensional (1-D) 4₁ helical chain in 1 with high-symmetry Pbca, and a 2₁ helical chain in 2 with lower symmetry P2₁/n, respectively. The two chains are further linked by L into two structure-correlated three-dimensional (3-D) architectures. PXRD and TG analysis confirmed the phase purity and stability of 1 and 2. The solid-state fluorescence properties of the prepared MOF revealed a maximum emission at 382?nm and 393?nm (λ_ex = 330?nm), ascribing to the intra-ligand transitions. Interestingly, an additional strong emission peak at 516?nm can be observed in 1 (below 400?°C), while the emission was silenced in 2. The additional emission band may be attributed to the subtle difference of architectural features and coordination configurations between in 1 and 2.     

Copolymerization of the poly(<Emphasis Type="Italic">N,N</Emphasis>-dimethyl-<Emphasis Type="Italic">N,N</Emphasis>-diallylammonium chloride) macromonomer with acrylamide

Copolymers of the poly(N,N-dimethyl-N,N-diallylammonium chloride) macromonomer (1′) with acrylamide (2) with a high content of cationic groups (up to 50%) were synthesized. The relative activities r _1′ and r ₂ were calculated. The relative activities calculated by the Kelen—Tudos (r _1′ = 0.057±0.009, r ₂ = 1.57±0.12) and Feynman—Ross (r _1′ = 0.055±0.011, r ₂ = 1.58±0.14) methods are in accordance. The intrinsic viscosity and the yield of copolymers were found to decrease with an increase in the molar fraction of macromonomer 1′ in the monomer mixture. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 515–518, March, 2007.     

Synthesis and DFT calculations of oxido and phenylimido-rhenium(V) complexes incorporating the N,O donor ligand 2-[(2-hydroxyethylimino)methyl]phenol

The reactions of equimolar amounts of trans-[ReOC1₃(PPh₃)₂] or trans-[Re(NPh)(PPh₃)₂Cl₃] with a Schiff base formed by condensation of 2-hydroxy-4-methoxybenzaldehyde and ethanolamine (H₂L) result in the formation of cis-[ReO(HL)PPh₃Cl₂] (1a) and trans-[Re(NPh)(HL)(PPh₃)Cl₂] (2b), respectively, in good yields. 1a and 2b have been characterized by a range of spectroscopic and analytical techniques. The X-ray crystal structures of 1a and 2b reveal that 1a is an octahedral cis-Cl,Cl oxorhenium(V) complex, while 2b is a trans-Cl,Cl phenylimidorhenium(V) complex. The complexes are weakly emissive at room temperature with quantum yields of 10^?4. Density functional theory calculations of the electronic properties of the complexes were performed and are in agreement with the experimental results. The complexes display quasi-reversible Re(V)/Re(VI) redox couples in acetonitrile. There is reasonable agreement between the experimental and calculated redox potentials of 1a and 2b.     

Spectroscopic,thermal and X-ray crystal structure studies of some bis-(pyrazine-2-carboxylato) nickel(II) complexes

Three nickel(II) complexes [Ni(PC)₂(H₂O)₂], 1, [Ni(PC)₂(TU)₂], 2 and [Ni(PC)₂(ABI)₂]· 2(H₂O), 3, PC?=?pyrazine-2-carboxylate, TU?=?thiourea and ABI?=?2-aminobenzimidazole, were synthesized and characterized by elemental analysis, IR spectroscopy and thermal analysis. The complexes were also investigated by single crystal X-ray diffraction analysis. Structures of the monomeric complexes showed nickel(II) chelated to two PC ions from an oxygen atom of carboxylate ion and the adjacent hetero nitrogen atom. The three complexes were crystallized in a monoclinic system with P2 ₁ /c space group for 1, while 2 and 3 had C2/c space groups. The structure of 1 showed two coordinated water molecules occupying the trans positions of a slightly elongated octahedron. The structure of 2 consisted of two PC ions and two thiourea molecules in trans positions. The structure of 3 was different and showed a highly distorted octahedron with two ABI molecules chelated to the nickel ion in cis positions through their hetero nitrogen atoms. Two water molecules of crystallisation were shown in the structure of 3.     

Synthesis,crystal structures and toxicity of bicadmium(ii) complexes with macrocyclic,hexaaza-bearing,hydroxyethyl pendants

Three bicadmium(II) complexes with hydroxyethyl pendants were synthesized by [2?+?2] Schiff-base condensation of 2-[bis(2-aminoethyl)amino]ethanol with sodium 2,6-diformyl-4-R-phenolate (for Complex 1, R?=?F; Complex 2, R?=?Cl; Complex 3, R?=?CH₃) in the presence of Cd²⁺. Crystals of 1 were monoclinic, space group P2₁/c, with a?=?16.251(9), b?=?21.424(11), c?=?12.994(7)?Å and β?=?106.622(9)°. Both Cd(II) atoms were heptacoordinated with monocapped-octahedral geometry. Complex 3 crystals were isolated as triclinic, space group P?1 with α?=?15.502(4), b?=?16.060(4), c?=?16.642(5)?Å and α?=?68.813(4), β?=?80.836(4), γ?= 86.551(4)°. The coordination number and coordination geometry of the Cd ion in one cationic unit of 3 are similar to that of 1, while in the other cationic unit, one Cd atom is N₃O₄ heptacoordinated and the other Cd atom has an N₃O₃ coordination environment and possesses a distorted octahedral geometry. The toxicity of these complexes was evaluated by testing antimicrobial activity against bacterial strands.     

四个基于间苯二(取代水杨醛酰腙)的有机锡配合物的溶剂热合成、结构和荧光性能

采用间苯二（取代水杨醛酰腙）（H₄L）与R₃²SnOH溶剂热反应,或间苯二甲酰肼、3-叔丁基水杨醛和三环己基氢氧化锡一锅溶剂热法反应,合成了4个新的有机锡配合物（SnR²）₂L（1~4）,其中,H₄L=m-Ph（CONH—N=CH（o-OH） PhR¹）₂;R¹=NEt₂,R²=Ph（1）;R¹=3,5-di-tert-butyl=3,5-t-2Bu,R²=Ph（2）;R¹=3,5-t-2Bu,R²=Cy（3）;R¹=3-tert-butyl=3-t-Bu,R²=Cy（4）。经元素分析、红外光谱和（¹H、¹³C、¹¹9Sn）核磁共振谱表征,并用X射线衍射方法确证配合物1~4的结构。配体H₄L的2个取代水杨醛酰腙链向内取向并与锡原子配位形成3个内向E型配合物1~3,取代水杨醛酰腙链向外取向并与锡原子配位形成外向E型配合物4。配合物1、2和4属于三斜晶系P1空间群,配合物3属于单斜晶系P2₁/c空间群。中心锡与配位原子构成畸形双角三锥构型。配体、配合物-三氯甲烷溶液的荧光性能表明,当具有弱荧光的配体m-Ph（CONH—N=CH（o-OH） PhNEt₂）₂（H₄L¹）和无荧光的配体m-Ph（CONH—N=CH（o-OH） Ph（3,5-t-2Bu））₂（H₄L²）分别与苯基锡、环己基锡配位后,配合物-三氯甲烷溶液发出强荧光。     

Cytotoxic oplopane sesquiterpenoids from Arnoglossum atriplicifolium

Pale Indian plantain (Arnoglossum atriplicifolium (L.) H. Rob.) is a plant with traditional medicinal usage among the Cherokee Native American tribe for treating cancer. Two oplopane sesquiterpenoids were isolated from an extract of A. atriplicifolium from Western North Carolina. The compounds were isolated by bioassay-guided fractionation using an MCF-7 breast tumour cell line assay. The known compound (1S,6R,7R,8R)-1-acetoxy-6,7-diangeloxy-8,10-epoxy-2-oxo-oplopa-3,14Z,11,12-dien-13-al (1) had an EC₅₀ value of 9.0 μM against MCF-7 cells, while the new compound (1S,3R,6R,7R,8R,11S)-1-acetoxy-6,7-diangeloxy-8,10,11,13-bisepoxyoplopan-2-one (2) had an EC₅₀ value of 96 μM. The compounds were characterised by 1D and 2D NMR spectroscopy and by comparison with literature values in the case for 1. Based on NOESY analysis, a correction of the relative configuration for 1 is presented. The presence of these compounds may help to explain the folk remedy usage of this plant as an anticancer agent.     

Syntheses,crystal structures,and urease inhibitory properties of copper(II) and zinc(II) complexes with 2-bromo-4-chloro-6-[(2-dimethylaminoethylimino)methyl]phenol

A new copper(II) complex, [CuL(μ _1,1-N₃)] _n (1), and a new zinc(II) complex, [ZnL(μ ₂-acetato-O, O′)₂] _n (2) (HL = 2-bromo-4-chloro-6-[(2-dimethylaminoethylimino)methyl]phenol), were prepared and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. Complex 1 is an end-on azide-bridged polynuclear copper(II) complex and 2 is a syn–anti bidentate acetate-bridged polynuclear zinc(II) complex. Each metal in the complex is five-coordinate with square-pyramidal geometry. Complex 1 shows good urease inhibitory properties, while 2 does not.     

不对称Salen配体的Ni(Ⅱ)/Cu(Ⅱ)/Mn(Ⅲ)配合物的合成及其晶体结构

将(1R,2R)-环己二胺与2-羟基-1-萘甲醛和3,5-二叔丁基水杨醛反应,得到非对称Salen配体H2L,然后将配体H2L与Ni(OAc)2·4H2O、Cu(OAc)2·H2O、Mn(OAc)2·4H2O进行配位反应,得到3个单核配合物[Ni(L)]·CH2Cl2(1),[Cu(L)](2),[Mn(L)(Cl)]·CH2Cl2(3),分别采用1H NMR、FT-IR和元素分析对化合物进行了表征,并通过X射线单晶衍射技术测定了配体和3个配合物的晶体结构。配体H2L属于正交晶系,P212121空间群。配合物1属于单斜晶系,P21/c空间群,而配合物2和配合物1的结构相似。配合物3属于三斜晶系,P1空间群。     

Chiral discotic derivatives of 1,3,5-triphenyl-6-oxoverdazyl radical

Two derivatives of 1,3,5-aryl-6-oxoverdazyl containing two 3,4,5-trioctyloxyphenyl and one 3,4,5-tri((S)-3,7-dimethyloctyloxy)phenyl group in position C(3) (1b) or N(1) (1c) were investigated by thermal, X-ray diffraction and magnetic methods. The results were compared to those obtained for achiral derivative 1a containing three 3,4,5-trioctyloxyphenyl groups. All three compounds exhibit an ordered columnar hexagonal phase, Col_h(o), and for chiral derivatives, 1b and 1c, a superstructure with doubled periodicity was found. The introduction of the three chiral alkoxy substituents in 1a lowered the mesophase stability by about 50 K and induced a Col_h phase in 1c. Thermochromic analysis showed a hypsochromic shift upon formation of the Col_h(o) phase similar for all three derivatives 1 (~0.3 eV), which coincides with a 5% drop in effective magnetic moment, μ_eff, for 1c. Analysis of magnetisation data in a range of 2–370 K at 200 Oe revealed weak antiferromagnetic interactions (θ = – 4 K) in the Col_h(o) phase.     

Manganese(II) complexes of hydrazone based NNO-donor ligands and their catalytic activity in the oxidation of olefins

The reaction between tridentate NNO donor hydrazone ligands, (E)-2-cyano-N′-(phenyl(pyridin-2-yl)methylene)acetohydrazide (HL¹) and (E)-2-cyano-N′-(1-(pyridin-2-yl)ethylidene)acetohydrazide (HL²), with MnCl₂·4H₂O in methanol resulted in [Mn(HL¹)Cl₂(CH₃OH)] (1) and [Mn(HL²)Cl₂(CH₃OH)] (2). Molecular structures of the complexes were determined by single-crystal X-ray diffraction. All of the investigated compounds were further characterized by elemental analysis, FT-IR, TGA, and UV–Vis spectroscopy. These complexes were used as catalysts for olefin oxidation in the presence of tert-butylhydroperoxide (TBHP) as an oxidant. Under similar experimental conditions with equal manganese loading, the presence of [Mn(HL²)Cl₂(CH₃OH)] (2) resulted in higher conversion than [Mn(HL¹)Cl₂(CH₃OH)] (1).     

A new trans-dioxorhenium(V) complex with 4-aminopyridine: synthesis,structure, electrochemical aspects,DFT, and TD-DFT calculations

The reaction of 1?:?4.4?M proportion of cis-[ReO₂I(PPh₃)₂] and 4-aminopyridine (ampy) in acetone–water gives trans-[ReO₂(ampy)₄]I·2H₂O (1a) in 85% yield. 1a has been characterized by C, H, and N microanalyses, FT-IR, UV–vis, ¹H NMR spectroscopy, and molar conductivity. The X-ray crystal structure of 1a reveals an octahedral trans dioxorhenium(V) complex with a “N₄O₂” coordination for rhenium. 1a has an orthorhombic space group C2221 with a?=?17.576(4), b?=?19.370(4), c?=?15.730(4) Å, V?=?5355(2) ų, and Z?=?8. Geometry optimization of the trans-O,O complex, 1a and its cis-O,O analog, 1b performed at the level of density functional theory reveal that 1a is more stable than 1b by 25?kcal M^–1 in the gas phase. The electronic spectrum of 1a was also analyzed at the level of time-dependent density functional theory. Excitation of 1a in methanol at 450?nm leads to a fluorescent emission at 505?nm with a quantum yield (Ф) of 0.04. Electrochemical studies of 1a in acetonitrile show a quasi-reversible Re(V) to Re(VI) oxidation at 0.618?V versus Ag/AgCl. This redox potential matches with the calculated redox potential of 0.621?V versus Ag/AgCl.     

Technetium(V) complexes of dithiocarbazate derivatives

The neutral complex [TcOCl(hdc)] (1) (hdc?=?S-methyl-β-N-(2-hydroxyphenylethylidene)dithiocarbazate) was prepared by reaction of (n-Bu₄N)[TcOCl₄] with an equimolar amount of H₂hdc in ethanol/dichloromethane at room temperature. With a fourfold mol excess of H₂hdc in methanol/acetone, the ‘3?+?2’ complex [TcO(hdc)(adc)] (2) (adc?=?S-methyl-β-N-(prop-2-ylidene)dithiocarbazate) was isolated. Adc was formed by ketone exchange between solvent acetone and the hydroxyacetophenone fragment of hdc. Compounds 1 and 2 were characterized by infrared spectroscopy, ¹H NMR spectrometry, elemental analysis and single-crystal X-ray crystallography. Complex 1 has square-pyramidal geometry with the SNO-donor atoms of the tridentate chelate hdc and chloride forming a square plane, with the oxo oxygen atom in the apical position. Complex 2 has a distorted octahedral geometry, with an S₂N₂ donor set in the equatorial plane and the oxo and phenolate oxygen atoms in trans apical positions.     

New chiral liquid crystal monomers and cholesteric polyacrylates: synthesis and characterisation

The synthesis of new chiral monomers (M₁ ?M₃ ) based on menthol and the corresponding polyacrylates (P₁ ?P₃ ) is described. The chemical structures, formula and phase behaviour of the obtained monomers and polymers were characterised with FT-IR, ¹H-NMR, elemental analyses, differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X-ray diffraction (XRD). The effect of the mesogenic core rigidity, spacer length and menthyl steric effect on the phase behaviour of M₁ ?M₃ and P₁ ?P₃ is discussed. The expected mesophase of the compounds based on menthol can be obtained by inserting a flexible spacer between the mesogenic core and the terminal groups. For the chiral monomers and polyacrylates, their corresponding melting temperature (T _m), glass transition temperature (T _g) and clearing temperature (T _i) increased with an increase of the mesogenic core rigidity; while the T _m, T _g and T _i decreased with increasing the spacer length. M₁ and P₁ showed no mesophase, while M₂ and M₃ all revealed a SmC* and cholesteric phases. P₂ and P₃ only showed a cholesteric phase.     

<Emphasis Type="Italic">iso</Emphasis>-<Emphasis Type="Italic">α</Emphasis>-Cyclopiazonic acid,a new natural product isolated from the marine-derived fungus <Emphasis Type="Italic">Aspergillus flavus</Emphasis> C-F-3

A new natural product, iso-α-cyclopiazonic acid (1), together with its isomer α-cyclopiazonic acid (2); three mycotoxins: aflatoxin B₁ (AFB₁) (3), aflatoxin Q₁ (AFQ₁) (4), and O-methylsterigmatocystin (OMST) (5); two diketopiperazine alkaloids: ditryptophenaline (6) and 3-[(1H-indol-3-yl)methyl]-6-benzylpiperazine-2,5-dione (7), were isolated from the marine-derived fungus Aspergillus flavus. Their structures were determined by analysis of spectroscopic data. The cytotoxicities of compounds 1 and 2 were studied using HL-60, MOLT-4, A-549, and BEL-7402 cell lines.     

Synthesis,structure, and antitumor properties of platinum(iv) complexes with aminonitroxyl radicals

The platinum(iv) complexes cis,trans,cis-Pt^IV(RNH₂)(NH₃)(OH)₂Cl₂, where R is 2,2,6,6-tetramethyl-1-oxyl-4-piperidinyl (1) or 2,2,5,5-tetramethyl-1-oxyl-3-pyrrolidinyl (2), were prepared by oxidation of the corresponding cis-Pt^II(RNH₂)(NH₃)Cl₂ complexes with hydrogen peroxide. The reactions are catalyzed by tungstate salts, which makes it possible to carry out oxidation under mild conditions. The resulting complexes were characterized by elemental analysis, HPLC, and IR, UV, and ESR spectroscopy. The structure of complex 1 was established by X-ray diffraction analysis. Complex 1 exhibits the highest antitumor activity in an experimental tumor, viz., in P388 leukemia. The resistance of the tumor to this complex developed much slower than that to Cisplatin.