A series of new hybrid compounds constructed from Dawson-type phosphomolybdates and metal–organic coordination complexes

In this study, a series of compounds based on Dawson-type phosphomolybdates, H₃(C₆NO₂H₆)₂[K(H₂O)₃(C₆NO₂H₅)₃][P₂Mo₁₈O₆₂] ? 5.5H₂O (1), (C₆NO₂H₆)₆[Ln(H₂O)₇(C₆NO₂H₅)₂]₂[P₂Mo₁₈O₆₂]₂·13.5H₂O (Ln = Ce (2), La (3)) have been synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopy methods, TG analysis, and single-crystal X-ray diffraction. Compound 1 consists of [P₂Mo₁₈O₆₂]^6? building units joined by potassium-pyridine-3-carboxylic acid complexes, resulting in a wavelike polyoxometalate (POM) chain, which further interacts with each other via intermolecular interactions to form a 3-D supramolecular channel framework containing guest water molecules. Compounds 2 and 3 possess a 3-D supramolecular framework with 1-D tunnel constructed from [P₂Mo₁₈O₆₂]^6? and mononuclear lanthanide coordination complex fragments. To the best of our knowledge, 1 not only represents the first example of 1-D hybrid assembly based on Dawson-type phosphomolybdate, but also the first hybrid compound constructed from Dawson-type POMs and alkali–metal coordination complex fragments.     

A series of novel 1D coordination polymers constructed from metal–quinolone complex fragments linked by aromatic dicarboxylate ligands

Self-assembly of quinolones with metal salts in the presence of aromatic dicarboxylate ligands affords a series of novel 1D metal–quinolone complexes, namely [Mn(Hppa)(oba)]·3H₂O (1), [Co(Hppa)(oba)]·3.25H₂O (2), [Zn(Hppa)(sdba)]·1.5H₂O (3), [Mn(Hcf)(bpda)(H₂O)]·2H₂O (4), [Mn(Hppa)₂(bpdc)] (5) and [Mn(Hlome)₂(bpdc)]·4H₂O (6) (Hppa = Pipemidic acid, Hcf = ciprofloxacin, Hlome = lomefloxacin). The structures of compounds 1–3 consist of novel polymeric chains spanning two different directions, which display an intriguing 1D → 3D inclined polycatenation of supramolecular ladders. Compound 4 exhibits a chain compound formed from the interconnection of [Mn₂(Hcf)₂(μ-CO₂)₂] dimers with bpda ligands. Compounds 5 and 6 are similar chain compounds constructed from [Mn(Hppa)₂] (or [Mn(Hlome)₂]) fragments linked by bpdc ligands. The magnetic properties of 4 have been studied, which indicate the existence of antiferromagnetic interactions. Furthermore, the luminescent properties of compound 3 are discussed.     

FeCl3-promoted formation of C–C bonds: synthesis of substituted quinolines from imines and electron-deficient alkynes

An efficient method for the synthesis of substituted quinolines is described. By FeCl₃-promoted C–C bond formation, 2,3-disubstituted and 2,3,4-trisubstituted quinolines were successfully synthesized from the reaction between imines and electron-deficient alkynes in good yields. The reaction can also be performed in a sequential three-component manner by using aromatic amines and aromatic aldehydes instead of the corresponding imines.     

Crystal structures of the N-salicylidene–L-serinatoaquacopper(II) monohydrate and its ternary derivative with 2-aminopyridine

The complexes [Cu(Sal–(L-Ser))H₂O]⋅H₂O 1 and [Cu(Sal–Ser)(2-amino pyridine)] 2 have been prepared and their crystal structures determined. In 1 the copper(II) has a square-pyramidal geometry, being coordinated to the tridentate Sal–(L-Ser) Schiff base ligand and the oxygen atom (O(16)) of one water molecule occupying the corners of a square. The coordination sphere about the copper is completed by an axial O(12) atom of an hydroxyl group belonging to an adjacent complex unit. In the racemic ternary complex 2 the metal atom has a square-planar coordination with O,N,O atoms of the tridentate Sal–Ser dianion and the heterocyclic N atom of the 2-aminopyridine. Spectroscopic data are discussed.     

Copper and zinc co-catalyzed synthesis of imidazoles via the activation of sp C–H and N–H bonds

An efficient and facile approach to synthesize imidazoles from amidines and arylketone via oxidative coupling of sp³ C–H bond and N–H bond is reported. This strategy exhibits high performance in terms of regioselectivity with moderate to high yields by using easily available materials, and provides an alternative method to synthesize multi-substituted imidazole skeletons.     

Crystal structures of two new dinuclear Ag(I) complexes constructed from 4,4′-biphenyldicarboxylic acid and N-containing ligands

The reaction of silver 4,4′-biphenyldicarboxylate with 1,3-diaminopropane (DAP) and 2-amino-5-methylpyridine (AMP) respectively results in the formation of two dinuclear silver(I) complexes: [Ag₂(DAP)₂](BPC)·2H₂O (1) and [Ag₂(BPC)(AMP)₄]·2H₂O (2), where BPC is 4,4′-biphenyldicarboxylate. The complexes are characterized by elemental analysis and X-ray crystallography. Complex 1 crystallizes in the triclinic system, P-1 space group, a = 8.585(2) Å, b = 8.849(2) Å, c = 9.890(3) Å, α = 107.893(3)°, β = 94.139(3)°, γ = 113.202(3)°, V = 640.9(3) ų, Z = 1. Complex 2 crystallizes in the triclinic system, P-1 space group, a = 11.818(3) Å, b = 13.132(4) Å, c = 13.281(4) Å, α = 92.571(4)°, β = 96.425(3)°, γ = 102.142(4)°, V = 1997.5(10) ų, Z = 2. Complex 1 consists of a macrocyclic dinuclear silver(I) dication, a 4,4′-biphenyldicarboxylate anion, and two water molecules of crystallization. Each Ag atom is in a linear coordination. Complex 2 consists of a dinuclear silver(I) complex molecule and two water molecules of crystallization. Each Ag atom is in a T-shaped coordination. The Ag...Ag separations are 5.127(2) Å in 1 and 3.172(2) Å in 2.     

Crystal structure of a π complex of AgBF4 with 2-allyl-5-phenyl-2H-tetrazole of the composition [Ag(C10H10N4)(BF4)]

Journal of Structural Chemistry - By the interaction of AgBF4 with 2-allyl-5-phenyl-2H-tetrazole (2aphet) in the ethanol solution, a π complex of [Ag(2aphet)(BF4)] is obtained which is studied...     

Synthesis of C1–C11 eribulin fragment and its diastereomeric analogues

A practical stereoselective synthesis of the central C1–C10 fragment of eribulin and its two diastereomeric analogues is developed. Our approach relied on the use of l-ascorbic acid as the starting material which allowed accessing a key intermediate with a syn diol moiety (C9 and C10 of eribulin) and a carboxylic ester group. A functionalized six membered lactone having several required hydroxyl groups was then obtained. In a number of steps, the lactone was converted to an intermediate for our key oxa-Michael reaction. A regio- and stereocontrolled intramolecular oxa-Michael reaction completed the synthesis of the C1–11 fragment having a trans-fused tetrahydropyrans with the exact stereochemistry of various hydroxyl groups, as in eribulin.     

Synthesis,structures and electrochemical properties of four organic–inorganic hybrid polyoxometalates constructed from polyoxotungstate clusters and transition metal complexes

Four novel organic–inorganic hybrid compounds [Cu₅ ^I(4,4′-bpy)₃(2,2′-bpy)₄][BW₁₂O₄₀] · H₂O (1), [Ni_0.5(2,2′-bpy)_1.25][Ni(2,2′-bpy)₃][Ni(2,2′-bpy)₂(H₂O)(SiW₁₁^VIW^VO₄₀)] · 0.5H₂O (2), [H₂bpy]₂[Zn(2,2′-bpy)₃]₂[Si₂W₁₈O₆₂] · 1.5H₂O (3) and [Cu^II(2,2′-bpy)₂]₂[SiW₁₂O₄₀] · 2H₂O (4) (2,2′-bpy = 2,2′-bipyridine, 4,4′-bpy = 4,4′-bipyridine) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermal gravimetric analysis, electrochemical measurements and single-crystal X-ray diffraction. Compound (1) is a novel [BW₁₂O₄₀]⁵⁻ polyoxoanion bisupported by copper(I) coordination cations with mixed 2,2′-bpy and 4,4′-bpy ligands. Compound (2) is constructed from the [SiW₁₁^VIW^VO₄₀]⁵⁻ polyoxoanions supported by [Ni(2,2′–bpy)₂]²⁺. Compound (3) is composed of a novel [Si₂W₁₈O₆₂]⁸⁻ cluster and [Zn(2,2′–bpy)₃]²⁺ complexes, which held together into a three-dimensional (3D) supramolecular network through hydrogen-bonding interactions. Compound (4) shows a 2D layer framework constructed from a bisupporting Keggin polyoxoanion cluster and [Cu(2,2′–bpy)₂]²⁺ coordination polymer fragments, resulting in 3D networks via supramolecular interactions. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A new isochroman-4-one derivative from the peel of Musa sapientum L. and its total synthesis

A new isochroman-4-one,7,8-dihydroxy-3-methylisochroman-4-one was isolated from water soluble fraction of Musa sapientum L.Its structure was determined by spectroscopic evidences and its total synthesis has also been reported.The compound showed potent antihypertensive activity.     

Charge density analysis of 2-methyl-4-nitro-1-phenyl-1H-imidazole-5-carbonitrile: an experimental and theoretical study of C≡N···C≡N interactions

The experimental charge density distribution was determined for 2-methyl-4-nitro-1-phenyl-1H-imidazole-5-carbonitryle, using the Hansen-Coppens multipole model. Free R factor calculations were performed with MoPro software to find optimal restraints for a physically meaningful model. The crystal packing is determined to some extent by weak C-H···O and C-H···N hydrogen bonds but mostly by a lateral electrostatic interaction between antiparallel side-by-side C≡N groups. Electrostatic energy calculations were performed based on the experimental data and are in line with the high-level, explicitly correlated theoretical SCS-RI-MP2-F12 calculations of total energy. The molecular dipole moment and atomic charge values were compared for different experimental and theoretical models, to highlight the dependence of the electrostatic property outputs on the applied restraints. Interesting O···O contacts are also described. The results are compared with two recently investigated nitroimidazole derivatives, namely, 1-(2'-aminophenyl)-2-methyl-4-nitroimidazole and 1-phenyl-4-nitroimidazole.     

A novel lutetium(III) acetate phthalocyanine directly substituted with N,N’-dimethylaminophenyl groups via CC bonds and its water-soluble derivative for photodynamic therapy

In this study, the novel 4-(N,N′-dimethylamino)phenyl substituted lutetium(III) acetate phthalocyanine (2) and its quaternized derivative (3) were synthesized via a Suzuki-Miyaura coupling reaction between tetrakis(iodo) lutetium(III)acetate phthalocyanine (1) and 4-(N,N-dimethylamino)phenylboronic acid, and subsequent quaternization using dimethyl sulfate, respectively. The obtained phthalocyanine 3 exhibited excellent solubility in water which is important for photodynamic therapy applications. Photophysical properties such as fluorescence quantum yield and fluorescence lifetime, and photochemical properties such as singlet oxygen generation and photostability were investigated to determine their suitability for photodynamic therapy. The lutetium(III) phthalocyanines, especially quaternized derivative 3, showed promising properties as potential photosensitizers for the treatment of cancer, producing higher singlet oxygen (Φ_Δ = 0.59) than motexafin lutetium (Φ_Δ = 0.31) which is a clinically used lutetium texaphyrin photosensitizer.     

Pd-catalyzed assembly of phenanthridines from aryl ketone O-acetyloximes and arynes through C–H bond activation

Pd-catalyzed annulation of aryne and aryl ketone O-acetyloxime via C–H bond activation was realized. Through the C–H bond activation/insertion/cyclization/elimination reaction sequence, phenanthridines are successfully constructed, providing an attractive strategy to approach substituted heterocycle without preactivation of starting materials.     

Dinuclear and polynuclear silver(I) saccharinate complexes with 1,3-diaminopropane and N-methylethylenediamine constructed from Ag?C interactions

New dinuclear and polynuclear Ag(I) complexes with the formula of [Ag₂(sac)₂(pen)₂] (1) and [Ag₂(sac)₂(nmen)]_n (2), (sac = saccharinate, pen = 1,3-diaminopropane, nmen = N-methylethylenediamine) have been synthesized and characterized by IR spectroscopy and thermal (TG/DTG, DTA) analysis. In addition, their structures were determined by single crystal X-ray diffraction technique. In 1, Ag(I) ions are doubly bridged by two pen ligands, besides pen ligands exhibit an interesting coordination mode by binding bridging ligand. Sac ligands connect to silver atom through its imino N atom. Furthermore, each Ag(I) ion exhibits a T-shaped coordination geometry. In 2, Ag(I) coordination environment is again T-shaped, including weak Ag-Ag bonds. The sac exhibits bidentate bringing mode, involving its imino nitrogen and carbonyl oxygen atoms, besides, bridging of Ag(I) centres by sac ligands results in argentophilic contacts. The polymeric units are assembled into two-dimensional networks by hydrogen bonds, C-H?π stacking interactions, weak Ag?C_sac (η²) and Ag?O interactions.     

Introduction of secondary pyridyl-1H-tetrazole derivatives into Keggin–Ag–(1,10-phenanthroline) system for tuning dimensionalities and architectures: assembly and properties

By introducing three pyridyl-1H-tetrazole derivatives to Keggin–Ag-(1,10-phenanthroline) system, five new polyoxometalate-based inorganic–organic hybrid compounds with different dimensionalities and structures, [Ag₃(4-ptz)₂Na(phen)(HPMo₁₂O₄₀)]·2H₂O (1), [Ag₄(3-ptz)₂(phen)₂(HPMo₁₂O₄₀)] (2), [Ag₄(3-ptz)₂(phen)₂(HVW₁₂O₄₀)] (3), [Ag₃(3-bptzb)(phen)₂(PMo₁₂O₄₀)] (4) and [Ag₃(3-bptzb)(phen)₂(VW₁₂O₄₀)] (5) (phen = 1,10-phenanthroline, x-ptzH = 5-(x-pyridyl)-1H-tetrazole (x = 3, 4), 3-bptzb = 1,4-bis(5-(3-pyridyl)-tetrazolyl)butane), have been synthesized under hydrothermal conditions. Compound 1 is a 1-D belt architecture constructed from an Ag-4-ptz metal–organic chain and two Ag–PMo₁₂O₄₀–Na–phen inorganic–organic chains. When 3-ptzH was introduced as secondary ligand in 2 and 3 instead of 4-ptzH, two isostructural architectures were obtained, which contain a 1-D zigzag Ag-3-ptz chain with phen ligands hanging on both sides of the chain. The Keggin anions connect adjacent Ag-3-ptz chains to construct 2-D networks. When the flexible 3-bptzb was selected, isostructural 4 and 5 with 2-D networks were obtained, which were constructed from binuclear subunits and Keggin–Ag inorganic chains. The influence of three pyridyl-1H-tetrazole derivatives as secondary ligands on the dimensionalities and architectures of 1–5 was discussed. The electrochemical and photocatalytic properties of the compounds were investigated.     

Rhodium(III)-catalyzed synthesis of indoles from 1-alkylidene-2-arylhydrazines and alkynes via C–H and N–N bond cleavages

1-Alkylidene-2-arylhydrazines undergo annulative coupling with internal alkynes in the presence of a rhodium(III) catalyst and a copper(II) salt. The reaction proceeds through cleavage of the C–H and N–N bonds of hydrazines to afford 1,2,3-trisubstituted indole derivatives.     

A series of novel Zn(Ⅱ) and Mn(Ⅱ) metal-organic frameworks constructed by 2,4-bis-oxyacetate-benzoic acid: syntheses,structures and photoluminescence

A new carboxylic acid ligand, 2,4-bis-oxyacetate-benzoic acid(H3BOABA), was designed and introduced to construct novel metal-organic framework materials. [Zn Na(BOABA)(phen)(H2O)]·H2O(1), Zn Na(BOABA)(2), Mn3(BOABA)2(phen)2(3), [Mn2(BOABA)(OH)]·(H2O)2(4)(CCDC: 885138, 885137, 894225, 883094) were hydrothermally synthesized and characterized by elemental analysis, IR spectra and thermal gravimetric analyses. Crystal structures of the complexes were determined by single crystal X-ray diffraction method. Complex 1 is a one dimensional double edges non-interpenetrated framework decorated by the phen ligands on the surface. Complex 2 is an unique three dimensional open framework, consisting of Zn(II) and Na(I). Complex 3 is an unique double edges one dimensional MOF containing a [Mn3(BOABA)2(phen)2]n non-interpenetrated structure. Complex 4 is a two dimensional plane structure containing two Mn atoms in the same coordination environment. The interaction between four complexes and DNA were studied by Et Br fluorescence probe. Meanwhile, photoluminescence studies revealed that these four complexes display strong fluorescent emission bands in the solid state at room temperature.     

First mechanosynthesis of piperlotines A,C, and derivatives through solvent-free Horner–Wadsworth–Emmons reaction

Piperlotines are natural products characterized by an α,β-unsaturated amide moiety. These compounds found wide applications in Medicinal Chemistry like antibacterials, cytotoxic agents, anticoagulants, among others. To date, diverse methods of synthesis have been reported for piperlotines, but involving the use of catalysts, hazard reagents, anhydrous media or coupling reagents. Thus, in this work, we developed a greener method of synthesis of piperlotines A, C, and derivatives, through mechanochemical activation under solvent-free conditions. The reaction of a β-amidophosphonate, K₂CO₃, and an aromatic aldehyde afforded target compounds in moderate to good yields (46–77%), in an open atmosphere by grinding. It is worth to mention that this mechanochemical process was under thermodynamic control because just E isomer was isolated for every reaction. Moreover, synthesized piperlotines have been predicted by means of chemoinformatic analysis as potential therapeutic agents for the treatment of arthritis or cancer.