Zeolites Promoting Quinoline Synthesis via Friedländer Reaction

Catalytic performance of zeolites H-BEA, H-MFI, H-FAU and H-MOR, exhibiting textural differences and with different Brønsted and Lewis acid sites concentration, have been studied in the synthesis of quinolines via Friedländer reaction. H-BEA and H-FAU efficiently promoted the condensation of 2-aminoaryl ketones 3 with ethyl acetoacetate (4a) or acetylacetone (4b) under mild reaction conditions, those being the first examples of zeolites as catalysts for this transformation. While H-FAU showed similar catalytic behaviour than that reported for (Al)SBA-15 affording mixtures of quinolines 5 and quinolones 6, H-BEA mainly led to quinolines 5 in almost total selectivity and good yields. However, H-MFI and H-MOR zeolites afforded quinolones 6 as the major reaction product. Methodology reported here was found to be useful for the synthesis of biologically active compounds with excellent yields avoiding unnecessary purifications protocols and tedious work-up procedures.     

Electrocatalytic Performances of Carbon Supported Metallophthalocyanine and Pt/Metallophthalocyanine Catalysts Towards Dioxygen Reduction in Acidic Medium

Electrocatalytic performances of phthalocyanines (Pcs) involving N-benzyl-4-phenyloxyacetamide moieties, dispersed on a high-surface area carbon substrate, Vulcan XC-72 (VC) and Nafion (Nf), towards oxygen reduction in acidic medium were determined and compared. The VC/Nf/CoPc(5) catalyst showed much higher catalytic activity than those of the other Pc(1–4)-based catalysts (H₂Pc 1, ZnPc 2, NiPc 3 and CuPc 4) and that of unsubstituted CoPc-based one. The comparison of the performance of VC/Nf/Pt-5 dual catalyst with that of VC/Nf/Pt one indicated that the former can be a good alternative to the latter as a cathode catalyst both in direct methanol and H₂/O₂ fuel cell applications.     

Synthesis and Structure of Octamethylcyclo-di(meta-silphenylenesiloxane)

Octamethylcyclo-di(meta-silphenylenesiloxane) 1 (cyclic meta-dimer) was synthesized from 1,3-bis(dimethylhydroxysilyl)benzene 7 in a dilute THF solution, in the presence of a catalytic amount of 4-dimethylaminopyridine (DMAP). In contrast, only small amounts of the cyclic meta-dimer 1, cyclic meta-trimer 2, cyclic meta-tetramer, etc. were obtained when the condensation reaction was carried out with the catalyst n-hexylamine 2-ethylhexoate or sodium hydroxide. The major product in these reactions is polymer 8. The structure of compound 1 was confirmed by X-ray crystallography. This cyclic molecule is most likely unstrained since the X-ray structure reveals that the Si–O–Si bond angle is 142.1(1)° which is similar to that in most unstrained siloxane compounds.     

Positions and Stereochemistry of Methyl Branches in the Novel Sex Pheromone Components Produced by a Lichen Moth, Lyclene dharma dharma

Female moths of Lyclene dharma dharma (Arctiidae, Lithosiinae) produce three sex pheromone components (I–III), for which we assigned the following novel chemical structures; 6-methyl-2-octadecanone (1) for I, 14-methyl-2-octadecanone (2) for II, and 6,14-dimethyl-2-octadecanone (3) for III. In the Iriomote Islands where the insects were collected, a lure including racemic 1 and 2 attracted the male moths without mixing 3. In this study for further confirmation of the plane structures, the positional isomers with a methyl branch at the 4-, 5-, 7-, 13-, or 15-position (4–8, respectively) were synthesized. The GC-MS analyses revealed that natural components I and II were best fitted with those of 1 and 2, respectively, among the methyl-2-octadecanones examined, indicating the usefulness of this analytical instrument and authentic standards for the determination of the positions of methyl branches. In field trapping tests, 4–8 could not substitute for 1 or 2, nor did these compounds inhibit the active binary lure of 1 and 2, indicating that the males strictly recognized the 2-ketones with a methyl branch at the 6- or 14-positions. Next, the absolute configurations of I and II were determined by HPLC with a normal-phased chiral column (Chiralpak AD-H), which could separate the enantiomers of both 1 and 2. The chiral HPLC analysis of a crude pheromone extract indicated that the females exclusively produced (S)-1 and (S)-2. Furthermore, a field evaluation of each enantiomer revealed that (S)-1 and (S)-2 were bioactive but (R)-1 and (R)-2 were not.     

Hydrothermal Synthesis, Crystal Structures and Fluorescent Properties of Two New d10 Metal Coordination Polymers with Two Mixed Flexible Ligands

Two complexes, [Zn(qda)(bpp)] _n (1) and {[Cd(qda)(bpp)₂]·2H₂O} _n (2), (H₂qda?=?hydroquinone-O,O′-diacetic acid, bpp?=?1,3-bis(4-pyridyl)propane), were hydrothermally synthesized and characterized by single crystal X-ray diffraction analysis, FTIR and elemental analysis. Both compounds exhibit two-dimensional structures. The qda anions in compound 1 adopt two different trans conformations, coordinating to Zn²⁺ ions in a monodentate fashion, while in compound 2 they adopt only one trans conformation yet keeping the same coordination fashion as in compound 1. The bpp molecules show same anti-gauche coordination conformation in both 1 and 2. In addition, photoluminescence for 1 and 2 has been investigated in the solid state at room temperature.     

Direct Synthesis and Crystal Structure of Dehydrated State in Vapochromic MMX-type Quasi-One-Dimensional Iodide-Bridged Platinum Complexes

The dehydrated vapochromic 1D coordination polymer, (H₃NC₄H₈NH₃)₂[Pt₂(pop)₄I] (1) was synthesized directly from methanol solution. Although vapochromic 1 · 4H ₂ O has been synthesized, dehydrated high-temperature structure has never been determined because of lowering the quality of crystal by dehydration. The crystal structure of 1 was determined by X-ray crystal structure analysis, and we confirmed that it was identical to the dehydrated high-temperature structure of 1 · 4H ₂ O by comparing the powder X-ray diffraction (XRD) patterns. The Pt–I–Pt distance (d(Pt–I–Pt)) of compound 1 · 4H ₂ O was shortened for approximately 1.1 Å by desorption of water to form compound 1, accompanied with phase transition in electronic states. The other crystal including methanol molecule as lattice solvent, 1 · 2MeOH, was also obtained as by-product. The synthesis from various kinds of organic solvent has the great potential to develop the field of vapochromism accompanying phase transition of electronic state.     

From 5-Hydroxymethylfurfural (HMF) to Polymer Precursors: Catalyst Screening Studies on the Conversion of 1,2,6-hexanetriol to 1,6-hexanediol

1,6-hexanediol (1) is an important polymer precursor for the polyester industry. In this paper, exploratory catalyst screening studies on the synthesis of 1 from 1,2,6-hexanetriol (2) are described via two different routes. The latter is available by a two-step procedure from 5-hydroxymethylfurfural (HMF, 3), a promising bio-based platform chemical. In the first approach, the direct catalytic hydrodeoxygenation of 2 to 1 with heterogeneous catalysts and molecular hydrogen was explored. Best results were obtained using a Rh?CReO_x/SiO₂ catalyst in water (180?°C, 80?bar H₂, 20?h reaction time), leading to full conversion of 2 and 73?% selectivity to 1, the main byproduct being 1,5-hexanediol (4). In a second approach, 2 was first converted to tetrahydropyran-2-methanol (2-THPM, 5) in quantitative yield using triflic acid as catalyst (125?°C, 30?min). Various catalysts were explored for the subsequent ring opening/hydrodeoxygenation of 5 to 1 using a hydrogenation protocol and the best results were obtained with a Rh?CReO_x/SiO₂ catalyst, viz. 96?% selectivity to 1 at 26?% conversion (120?°C, 80?bar H₂, 20?h).     

Synthesis, Surface-Active Properties, and Anthelmintic Activities of New Cationic Gemini Surfactants Against the Gastrointestinal Nematode, Heligmosomoides polygyrus bakeri, In Vitro

A novel series of cationic dimeric surfactants was prepared involving the ketalization reaction, Williamson etherification, and regioselective oxirane ring opening with tertiary alkyl amines. The synthesized compounds were obtained in high purity by a simple purification procedure using column chromatography. The critical micelle concentration (CMC), effectiveness of surface tension reduction (??_CMC), surface excess concentration (??), and area per molecule at the interface (A) were determined and values indicate that the cationic series is characterized by good surface-active and self-aggregation properties. For the first time, we reported the anthelmintic activities against the rodent gastrointestinal nematode Heligmosomoides polygyrus bakeri, in vitro for cationic gemini compounds. In the series of five tested cationic compounds (4a?Ce), three of them (4a, 4b and 4d) were shown to have an excellent anthelmintic activity in vitro at different concentrations. The anthelmintic activity was found to be dependent on the type of cationic compound, concentration and incubation time. The cationic di-C₁₂ (4a) derivate of the series was the best anthelmintic agent, its use was optimal at a minimum concentration of 50?ppm and with 60?min of incubation.     

Synthesis, Crystal Structure and Luminescent Property of a New Two-Dimensional Zn(II) Coordination Polymer Based on Oxalic Acid and 1,4-Bis(imidazol-1-ylmethyl)-benzene

A new Zn(II) coordination polymer based on oxalic acid and 1,4-bis(imidazol-1-ylmethyl)benzene (bix), namely, [Zn(C₂O₄)(bix)]_n (1), has been successfully synthesized under hydrothermal conditions. Its structure has been determined by single crystal X-ray diffraction analysis, elemental analyses and IR spectroscopy. Compound 1 shows a two-dimensional (2D) layer structure. The intermolecular C–H···O interactions extend the compound 1 into 3D supramolecular architectures and play an important role in stabilizing compound 1. In addition, the luminescent property of the compound has also been investigated in solid state at room temperature.     

Hydrothermal Synthesis, Crystal Structures and Fluorescent Properties of Two Complexes Based on 1,2-Phenylenedioxydiacetic Acid and Polypyridyl Ligands

Hydrothermal reactions of flexible 1,2-phenylenedioxydiacetic acid (H₂pda) with zinc nitrate or cadmium nitrate in the presence of auxiliary 4,4′-bypyridine (bpy) or 1,3-bis(4-pyridyl)propane (bpp) ligands gave rise to two coordination polymers, {[Cd₂(pda)₂(bpy)(H₂O)₂]·4H₂O} _n (1) and [Zn(pda)(bpp)] _n (2). The polymers were characterized by elemental analysis, IR, TG, and single-crystal X-ray diffraction methods. Compound 1 shows 1D ribbon structure and compound 2 displays twofold parallel interpenetrated 2D?→?2D architecture. The different conformations of pda anions in these two compounds are mainly induced by different metal coordination configurations in compound 1 and 2. In addition, the photoluminescence emission of 1 and 2 has been investigated in the solid state at room temperature.     

Targeted Highly-Thermostable Metal–Organic Frameworks Directed by Imidazole: Syntheses, Structures, Thermal Behaviors and Luminescent Properties

Three new isostructural 3D lanthanide MOFs (Ln(HBPTC)(H₂O)) (Ln = Tb (1), Pr (2), Nd (3); H₄BPTC = 3,3′,4,4′-biphenyltetracarboxylic acid) have been synthesized under hydrothermal conditions using imidazole as a structure-directing agent, and characterized by elemental analyses, IR, thermogravimetric analyses (TGA) and powder X-ray diffraction (PXRD) analyses. Topologically, compounds 1–3 demonstrate an intriguing 3D (6, 6)-connected network with the Schläfli symbol of (4¹⁰·6⁵)(4⁹·6⁶); and if the dinuclear (Ln₂) clusters are considered as the single 8-connected nodes, they can be described as a scarcely reported (4, 8)-connected alb net constructed from two intertwining sqp-4 nets. TGA and PXRD analyses reveal that compounds 1–3 exhibit high thermal stability, at least being stable up to 410 °C. Furthermore, the luminescence studies were performed on compound 1 and its dehydrated phase in the solid state at room temperature. The results demonstrate that compound 1 displays intense green emission, implying its potential application as fluorescence material. And the luminescence of 1 is quenched when removing the coordinated water molecules.     

Synthesis,Crystal Structures,Luminescence, Biological and Catalytic Properties of Two d10 Metal-Organic Coordination Polymers Constructed from Mixed Ligands

Two d¹⁰ metal-organic coordination polymers, [Cd₂(4-cpa)₄(bmip)₂]_n (1) and [Zn(4-cpa)₂(4,4′-bpy)]_n (2), [4-cpa = 4-chlorophenylacetate, bmip = 1,3-bis(2-methylimidazoly)propane, 4,4′-bpy = 4,4′-bipyridine], were hydrothermally synthesized and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA), powder X-ray diffraction and single-crystal X-ray diffraction. Single-crystal X-ray diffraction studies indicated that both 1 and 2 display analogous wave-like infinite chain structures. The two coordination polymers are further extended into 3D supramolecular structures through π···π stacking interactions and C–H···O hydrogen bonds for 1 and π···π stacking interactions, C–H···π stacking interactions and C–H···O hydrogen bonds for 2. Both 1 and 2 emit the intense blue luminescence at room temperature. The 4-Hcpa ligand and complexes 1 and 2 have been screened for their herbicidal activities against Brassica napus L. and Echinochloa crusgalli L. The results are compared with the activity of quizalofop-P-ethyl. Both compounds exhibit high catalytic properties on degradation of methyl orange in Fenton-like process.     

Synthesis, Analysis, and Field Activity of Sordidin, a Male-Produced Aggregation Pheromone of the Banana Weevil, Cosmopolites sordidus

An efficient synthesis of the diastereoisomers of sordidin (1), a male-produced aggregation pheromone of Cosmopolites sordidus, has been developed from commercially available 4-methylpent-4-en-2-ol (2). Preparation of exo-β-sordidin (1a) and endo-β-sordidin (1b) is via the anti epoxide, 4d, which is derived via iodocarbonation of 2. The endo-α-sordidin (1c) and exo-α-sordidin (1d) are prepared from the corresponding syn epoxide, which is available via stereo-controlled epoxidation of the triisopropylsilyloxy derivative, 3b. Silyloxy derivatives of the epoxides, 4, efficiently alkylate the anions of N-cyclohexyldiethylketimine (6a) and 3-pentanone N,N-dimethylhydrazone (6b). Acidic work-up of these alkylation reactions promotes cyclization to give 1. Gram quantities of 1a?1d, 1a + 1b and 1c + 1d have been prepared by this route. In field tests in a banana plantation in Costa Rica, compounds 1a?1d significantly increased capture rates of standard pseudostem traps. Comparable numbers of adults were attracted to pseudostem traps baited with the major naturally occurring isomers of sordidin 1c + 1d or 1a?1d. Although addition of the minor naturally occurring isomers of sordidin (1a and 1b) to pseudostem traps increased capture rates above controls, these compounds did not increase attraction of pseudostem traps to the same extent as 1a?1d. In comparison tests with conventional pseudostem traps, significantly more adults were trapped in water-containing pitfall traps baited with 1a?1d.     

Synthesis and biodegradability assessment of poly(amide-imide)s containing N-trimellitylimido-l-amino acid and 5-(2-benzimidazole)-1,3-phenylenediamine

This paper addressed construction and biodegradability assessment of chiral synthetic poly(amide-imide)s (PAI)s. These polymers were prepared by polycondensation reaction of chiral diacids; N-trimellitylimido-S-valine (7a), and N-trimellitylimido-l-leucine (7b) with 5-(2-benzimidazole)-1,3-phenylenediamine (4) in the presence of tetrabutylammonium bromide as a green media under microwave irradiation. The morphology observations of the aforementioned polymers exhibit that these macromolecules are nanostructured particle and so, good candidate as carrier for biomedical application. Furthermore, in vitro toxicity and soil biodegradability test of the different synthetic diacids (7a, 7b) and the obtained PAIs were employed to evaluate the biological activity of these materials. In Petri plate technique, the monomers and obtained polymers exposed on glass lamels were all colonized by fungal saprophytes and due to this invasion, a weight loss up to 35 % was observed in the material. The soil burial test and measuring dehydrogenase activity revealed that the aforementioned monomers and polymers are biologically active and probably biodegradable under the soil. Normal wheat seedling growth took place in the vials containing the aforesaid monomers and polymers. It could be concluded that the synthesized monomers and their polymers are biologically active, and they are nontoxic to ecosystems and natural environments.     

Construction of Three New Coordination Polymers Based on Dicarboxylate and Different Organic N-Donor Ligands

Three new metal coordination polymers, {[Ni₂(L₁)₂(bip)₂]·H₂O} _n (1), [Zn₂(L₂)₂(bih)_0.5] _n (2) and [Cd(L₂)(bih)_0.5] _n (3) [H₂L₁?=?2-(3-carboxyphenoxy)benzoic acid, H₂L₂?=?2-(4-carboxyphenoxy) benzoic acid, bip?=?4,4??-bis(2-imidazol-1-ylmethyl) biphenyl and bih?=?1,6-bis(2-methylimidazol-1-yl) hexane], have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Compound 1 is a one-dimensional ladder-like chain structure. Compound 2 is a two-dimensional layer structure. In compound 3, the alternate arrangement of the right- and left-handed helical chains through bih ligands interactions, which lead to form a two-dimensional framework. In compound 1, 2 and 3, the L₁ and L₂ ligands act as bridging ligands, exhibiting three coordination modes to link metal ions: bis-monodentate, bidentate chelating and monodentate modes. Moreover, the luminescent properties of compound 2 and 3 were also investigated in this work.     

Electroactive polymer actuator from highly doped permethylpolyazine dispersed in ethylene propylene diene elastomer

Structural, electronic, and optical properties of a series of ??-conjugated thiophene oligomers P1-P3 and CF ₃ P1-CF ₃ P3 have been theoretically investigated. P1-P3 contain the 2- (trifluoromethyl) thieno [3, 4-b] thiophene moiety as the centre and 1?C3 repeating thiophene units adjacent to its two sides respectively, while their corresponding derivatives CF ₃ P1-CF ₃ P3 with the CF₃ as end-caps. The geometric structures of the oligomers in the ground and excited state were optimized by PBE1PBE and CIS methods with 6?C31G (d) basis sets, respectively. All the oligomers exhibit zigzag arrangements. The absorptions and emissions were calculated by the time-dependent density functional theory method (TD-PBE1PBE). The lowest-lying absorptions of all the oligomers can be characterized as ??-??^* electron transition. For each series of oligomers, there is a progressive lowering in HOMO-LUMO gap with the increase of the repeating unit, being consistent with the red-shifted trend in the lowest-lying absorption and fluorescence from P1 to P3 and CF ₃ P1 to CF ₃ P3. To compare the P- and corresponding CF ₃ P-oligomers, the end-cap CF₃ group causes the slight blue shifts in absorption and emission spectra. The ionization potentials (IP_S), electron affinities (EAs), and reorganization energies (??) as well as the hole/electron extraction energies (HEP/EEP) of the oligomers were explored and those of the corresponding polymer were obtained by extrapolation method. The IP and HEP of P-polymer are lower than those of CF ₃ P-polymer, indicating that the P-polymer is more suitable for hole transport than CF ₃ P-polymer, while the higher EA and EEP for CF ₃ P-polymer suggest the better electron transfer property. For CF₃ end-caps, the CF ₃ P-polymer exhibits the equal reorganization energy between electron and hole, which is a precondition for the charge transfer balance.     

A Two-Dimensional Semiconductive Cu2I2-Based Layered-Structure with Rigid Conjugated Tris-Bidentate Tripodal Schiff-Base Chelator

A two-dimensional (2D) layered structure 1 with (6,3) topology was constructed from Cu₂I₂ dimer and rigid conjugated tripodal tris-bidentate Schiff-base chelator L, wherein Cu₂I₂ dimer acts as a two-connecting inorganic node and L ligand works as a triangular three-connecting synthon. Compound 1 has been well structurally elucidated by single-crystal X-ray diffraction. Solid-state diffuse-reflectance UV–Vis spectra show that compound 1 exhibits a much lower optical band gap (Eg) of 1.85 eV compared to its individual components (Eg(CuI) = 3.1 eV, Eg(L) = 2.87 eV).     

Polymerization of propylene catalyzed by α-diimine nickel complexes/methylaluminoxane: catalytic behavior and polymer properties

α-Diimine nickel dibromide complexes of dibromo[N,N’-bis(2,6-diisopropylphenyl)-2,3-butanediimine]nickel(II) (A) and dibromo[N,N’-(phenanthrene-9,10-diylidene)bis(2,6-diisopropylaniline)]nickel(II) (B) were synthesized under controlled conditions. The catalysts A, B and mixed of 1:1 weight ratio of them (C) were activated by methylaluminoxane and were used for propylene polymerization in a semi-batch reactor. In study of the catalytic systems behavior, activities, glass transition temperature (T _g) and viscosity average molecular weight (M _v) values related to the catalyst C were between those related to the catalysts A and B under same conditions. The highest and the lowest molecular weights of the obtained polymers were produced by the catalysts B and A which were about 80,000 and 70,000 (g/mol) under same conditions, respectively. The T _g of polypropylenes produced by the catalysts was about ?34 °C. The resulting polymers had similar behavior with ethylene-propylene copolymer which it could be due to formation of ethylene-type units in the polymer chain.     

Synthesis of 6-Substituted 1-oxoindanoyl Isoleucine Conjugates and Modeling Studies with the COI1-JAZ Co-Receptor Complex of Lima Bean

The conjugates of 6-substituted 1-oxoindanoyl carboxylic acids with L-isoleucine are mimics of the plant hormone (+)-7-iso-JA-L-Ile (3) that controls and regulates secondary metabolism and stress responses. In order to generate ligands that can be used as hormone-like compounds possessing different biological activities, an efficient and short synthesis of 6-bromo-1-oxoindane-4-carboxylic acid opens a general route to 6-Br-1-oxoindanoyl L-isoleucine conjugate (Br-In-L-Ile) (9a) as a key intermediate for several bioactive 6-halogen-In-L-Ile analogs (7a, 8a, 10a). The 6-ethynyl-In-L-Ile analog (11a) might be a valuable tool to localize macromolecular receptor molecules by click-chemistry. The activities of In-Ile derivatives were evaluated by assays inducing the release of volatile organic compounds (VOCs) in lima bean (Phaseolus lunatus). Each compound showed slightly different VOC induction patterns. To correlate such differences with structural features, modeling studies of In-Ile derivatives with COI-JAZa/b/c co-receptors of P. lunatus were performed. The modeling profits from the rigid backbone of the 1-oxoindanonoyl conjugates, which allows only well defined interactions with the receptor complex.     

A Series of Luminescent Lanthanide–Organic Complexes Constructed from In Situ Generated Dithiobenzoic Acid

Two types of lanthanide thiolato-carboxylate complexes, [Type I: [Yb(dtba) (Hdtba)] _n (1), Type II: [Ln(dtba)_1.5(biim)] _n (Ln = Pr (2a), Nd (2b), Sm (2c), Eu (2d), Gd (2e), Tb (2f), Dy (2g), H₂dtba = 2,2′-dithiodibenzoic acid, bimm = diimidazole)] have been obtained by hydrothermal method and characterized by the single-crystal X-ray diffraction, IR, 2D-COS IR, TG and the luminescence analysis. The H₂dtba ligand came from the in situ S–S function reaction of 2-mercaptobenzoic acid (H₂mba) under the hydrothermal condition. Complex 1 is a 2D bamboo-like sqr-topology layered structure, and the 3D (4, 4, 6)-connected supramolecular frameworks is produced by the hydrogen bonds of O–H···O. Complexes of type II (from 2a to 2g) are isostructural and they are assigned to 1D rope-like chains by introducing the chelating ligand of diimidazole. These 1D rope-like chains are further linked by N–H···O hydrogen bonds into a 3D supramolecular framework with CdSO₄-type topology. Photoluminescence studies reveal that complexes 2b, 2c, 2d, 2f, 2g exhibit strong lanthanide characteristic emission bands in the solid state at room temperature.