The Experts below are selected from a list of 807 Experts worldwide ranked by ideXlab platform
Junji Watanabe - One of the best experts on this subject based on the ideXlab platform.
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high pressure synthesis and properties of aliphatic aromatic polyimides via nylon salt type monomers derived from aliphatic diamines with Pyromellitic Acid and biphenyltetracarboxylic Acid
Macromolecules, 1997Co-Authors: Tatsuo Inoue, Yoshihiro Kumagai, Masaaki Kakimoto, Yoshio Imai, Junji WatanabeAbstract:Two aliphatic series of polyimides having well-defined structures with inherent viscosities of 0.4−2.7 dL g-1 were readily synthesized by the solid-state thermal polycondensation under high pressure of the salt monomers composed of aliphatic diamines having 6−12 methylene units and both Pyromellitic Acid (PMA) and biphenyltetracarboxylic Acid (BPA) under 220 MPa at 250 °C for 5 h. It is noteworthy that the polycondensation proceeded rapidly with the elimination of water in a closed reaction vessel under high pressure, producing high molecular weight polyimides mostly within only 1 h. The thermal behavior (melting temperature and glass transition temperature) and crystallinity of the PMA- and BPA-based polyimides are also discussed in detail.
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rigid rod polyesters with flexible side chains based on 1 4 dialkyl esters of Pyromellitic Acid and 4 4 biphenol 5 high resolution 13c nmr studies for crystalline and liquid crystalline layered phases
Macromolecules, 1994Co-Authors: Masato Sone, Brian R Harkness, Hiromichi Kurosu, Isao Ando, Junji WatanabeAbstract:Rigid-rod aromatic B-Cn polyesters with long alkyl side chains, composed of 1,4-dialkyl esters of Pyromellitic Acid and 4,4'-biphenol, form two distinct types of crystalline phases, K1 and K2, depending on the length of alkyl side chain. These crystalline phases are characterized by a layered structure, in which the aromatic main chains are packed into a layer with the side chains crystallized in the space between the layers. The detailed structures for these two crystalline phases were studied by 13 C solid-state NMR spectroscopy from which it was found that there are remarkable differences in the main-chain conformation and in the packing structure of the side chains
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rigid rod polyesters with flexible side chains 4 thermotropic behavior and phase structures in polyesters based on 1 4 dialkyl esters of Pyromellitic Acid and 4 4 biphenol
Macromolecules, 1994Co-Authors: Junji Watanabe, Brian R Harkness, Masato Sone, Hideo IchimuraAbstract:A series of rigid-rod polyesters with long alkyl side chains, denoted as B-Cn, have been prepared by condensing 1,4-diallyl esters of Pyromellitic Acid with biphenol. The alkyl side-chain lengths were varied from hexyl (n=6) to octedecyl groups (n=18), and the thermotropic transition behavior and mesophase structure of these material were examined by optical microscopy, DSC, and X-ray measurements. An increase in the length of the side chain decreases remarlably the melting point of the crystalline phase, giving rise to a liquid crystalline phase. Two types of liquid crystalline phases with layerlike modifications, LC-1 and LC-2, have been observed. The transition behavior of these liquid crystalline phases is described as a function of the side-chain length
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rigid rod polyesters with flexible side chains based on 1 4 dialkylesters of Pyromellitic Acid ii mesogenic properties of h cn polyesters prepared from 1 4 dialkylesters of Pyromellitic Acid and hydroquinone
Polymer Journal, 1992Co-Authors: Junji Watanabe, Brian R Harkness, Masato SoneAbstract:Rigid-rod polyesters with long alkyl side chains, denoted as H-Cn, have been prepared by reacting 1,4-dialkylesters of Pyromellitic Acid with hydroquinone. The alkyl groups were varied from hexyl (n=6) to octadecyl (n=18). The mesomorphic properties and structure of these polyesters were examined by optical microscopy, DSC and X-ray measurements. The experimental results indicate that the H-Cn polyesters with side-chain lengths of n≥12 exhibit liquid crystalline mesophases with a characteristic layered structure. In this structure, the aromatic main chains in the extended form pack into layers with one-dimensionally positional order in the lateral direction and the alkyl side chains in the disordered form occupy the space between the layers. This layered structure is considered to result from a kind of microphase separation of the aromatic and aliphatic components of the polymer, which results in an unusually observed increase in the isotropization temperatures of liquid crystals with an increase in the side-chain length.
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rigid rod polyesters with flexible side chains based on 1 4 dialkyl esters of Pyromellitic Acid 1
Macromolecules, 1991Co-Authors: Brian R Harkness, Junji WatanabeAbstract:Polyesters [O-Ar-OCO-Ph(COOR) 2 CO] n (Ar= Ph (I), Ph-Ph (II); R= C 14 H 29 ) were prepared and studied. X-ray examination of the mesophases of these polymers showed that they adopt layered structures. Polymer II displays two distinct layerlike modifications which depend on temperature, whereas the mesophase of I assumes a single layered structure that has a greater degree of order than the mesophase of II.
Kumar Biradha - One of the best experts on this subject based on the ideXlab platform.
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cocrystals and salts of pyridine 3 5 bis 1 methyl benzimidazole 2 yl with Pyromellitic Acid aromatic guest inclusion and separation via benzimidazole carboxylic Acid heterosynthon
Crystal Growth & Design, 2015Co-Authors: Avishek Dey, Saibal Bera, Kumar BiradhaAbstract:An arc-shaped molecule pyridine-3,5-bis(1-methyl-benzimidazole-2-yl) was shown to form cocrystals and salts with Pyromellitic Acid (H4PMA) which are sustained by COOH···Nbim/COO–···Hbim heterosynthons. The reaction between these two components in the presence of large aromatic guest molecules resulted in the crystals of salts with aromatic inclusion, while the absence of guests resulted in the H2O and EtOH solvates of cocrystals. The crystal structures of salts exhibited isostructurality with the inclusion of aromatics such as pyrene, perylene, phenanthrene, and 9-anthraldehyde. The crystal structures of solvates were found to differ significantly despite having similar composition. In all these structures the −COOH functional group has exhibited significant preference to interact with the benzimidazole moiety over the pyridine moiety. The aromatic guest inclusion was found to occur via cation···π interactions between the protonated benzimidazole and π-cloud of guest molecules. The competitive experiments...
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Cocrystals and Salts of Pyridine-3,5-bis(1-methyl-benzimidazole-2-yl) with Pyromellitic Acid: Aromatic Guest Inclusion and Separation via Benzimidazole–Carboxylic Acid Heterosynthon
2015Co-Authors: Avishek Dey, Saibal Bera, Kumar BiradhaAbstract:An arc-shaped molecule pyridine-3,5-bis(1-methyl-benzimidazole-2-yl) was shown to form cocrystals and salts with Pyromellitic Acid (H4PMA) which are sustained by COOH···Nbim/COO–···Hbim heterosynthons. The reaction between these two components in the presence of large aromatic guest molecules resulted in the crystals of salts with aromatic inclusion, while the absence of guests resulted in the H2O and EtOH solvates of cocrystals. The crystal structures of salts exhibited isostructurality with the inclusion of aromatics such as pyrene, perylene, phenanthrene, and 9-anthraldehyde. The crystal structures of solvates were found to differ significantly despite having similar composition. In all these structures the −COOH functional group has exhibited significant preference to interact with the benzimidazole moiety over the pyridine moiety. The aromatic guest inclusion was found to occur via cation···π interactions between the protonated benzimidazole and π-cloud of guest molecules. The competitive experiments on guest inclusion reveal that the two-component host system exhibits selective inclusion of perylene or 9-anthraldehyde over other aromatics such as pyrene or phenanthrene
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carboxylic Acid and phenolic hydroxyl interactions in the crystal structures of co crystals clathrates of trimesic Acid and Pyromellitic Acid with phenolic derivatives
Crystal Growth & Design, 2010Co-Authors: Lalit Rajput, Navendu Jana, Kumar BiradhaAbstract:Crystallization of trimesic Acid (H3TMA) in the presence of phenol resulted in the single crystals of [(H3TMA)·(phenol)], 1. The crystal structure consists of two-dimensional hydrogen bonding layers with herringbone geometry via an Acid-phenol synthon in which the O−H group of phenol inserts into a conventional Acid dimer in an unsymmetrical fashion. The consistency and robustness of this observed phenomenon were confirmed by reproducing a similar structure by treating H3TMA with m-cresol [(H3TMA)·(m-cresol)], 2. On the other hand, similar reactions with H4PMA resulted in unprecedented clathrates of H4PMA containing a square grid network via a conventional Acid synthon. The square grids have dimensions of 8.3 × 8.3 A and clathrate phenolic guests. Our studies indicate that H4PMA can act as a host only for the phenolic derivatives such as phenol [(H4PMA)·(phenol)], 3, o-cresol [(H4PMA)2·(o-cresol)], 4, p-cresol [(H4PMA)2·(p-cresol)], 5, and p-chlorophenol [(H4PMA)2·(p-chlorophenol)], 6.
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supramolecular isomerism and polymorphism in dianion salts of Pyromellitic Acid
Crystal Engineering, 1998Co-Authors: Kumar Biradha, Michael J ZaworotkoAbstract:Abstract The X-ray crystal structures of several salts of Pyromellitic Acid, H4PMA, have been determined. The structures of the pyridinium, [C6H5NH]2[H2PMA], 1, 3-methylpyridinium, [3-CH3C6H4NH]2[H2PMA], 2a, [3-CH3C6H4NH]2-[H2PMA]·[3-CH3C6H4N], 2b, 4-methylpyridinium, [(4-CH3C6H4N)2H][4-CH3C6H4NH][H2PMA], 3, 2-ethylpyridinium, [2-CH3CH2C6H4N]2[H2PMA], 4, 2,4,6-trimethylpyridinium, [2,4,6-(CH3)3C6H4NH]2[H2PMA], 5a and 5b, and quinolinium, [C9H7NH]2[H2PMA], 6, salts were characterized and analyzed in terms of their networking and crystal packing. The structures of 1–6 reveal the existence of 0D, 1D, 2D, or 3D O-H···O− hydrogen bonded networks that are sustained and controlled by self-assembly of H2PMA2− anions. Five structures, 1, 2a, 3, 4, and 6 form 0D complexes, whereas 1D, 2D, and 3D networks occur in 5a, 2b, and 5b, respectively. The relatively high occurrence of the 0D species might be attributable to a greater likelihood that more efficient crystal packing should generally occur in 0D complexes when compared to higher dimensional networks, in which open spaces are more likely. The formation of such a variety of networks by a single tecton, supramolecular isomerism, resembles that which has been observed in coordination polymer networks in which 4,4′-bipyridine or related ligands are used as spacer ligands.
Masato Sone - One of the best experts on this subject based on the ideXlab platform.
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rigid rod polyesters with flexible side chains based on 1 4 dialkyl esters of Pyromellitic Acid and 4 4 biphenol 5 high resolution 13c nmr studies for crystalline and liquid crystalline layered phases
Macromolecules, 1994Co-Authors: Masato Sone, Brian R Harkness, Hiromichi Kurosu, Isao Ando, Junji WatanabeAbstract:Rigid-rod aromatic B-Cn polyesters with long alkyl side chains, composed of 1,4-dialkyl esters of Pyromellitic Acid and 4,4'-biphenol, form two distinct types of crystalline phases, K1 and K2, depending on the length of alkyl side chain. These crystalline phases are characterized by a layered structure, in which the aromatic main chains are packed into a layer with the side chains crystallized in the space between the layers. The detailed structures for these two crystalline phases were studied by 13 C solid-state NMR spectroscopy from which it was found that there are remarkable differences in the main-chain conformation and in the packing structure of the side chains
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rigid rod polyesters with flexible side chains 4 thermotropic behavior and phase structures in polyesters based on 1 4 dialkyl esters of Pyromellitic Acid and 4 4 biphenol
Macromolecules, 1994Co-Authors: Junji Watanabe, Brian R Harkness, Masato Sone, Hideo IchimuraAbstract:A series of rigid-rod polyesters with long alkyl side chains, denoted as B-Cn, have been prepared by condensing 1,4-diallyl esters of Pyromellitic Acid with biphenol. The alkyl side-chain lengths were varied from hexyl (n=6) to octedecyl groups (n=18), and the thermotropic transition behavior and mesophase structure of these material were examined by optical microscopy, DSC, and X-ray measurements. An increase in the length of the side chain decreases remarlably the melting point of the crystalline phase, giving rise to a liquid crystalline phase. Two types of liquid crystalline phases with layerlike modifications, LC-1 and LC-2, have been observed. The transition behavior of these liquid crystalline phases is described as a function of the side-chain length
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rigid rod polyesters with flexible side chains based on 1 4 dialkylesters of Pyromellitic Acid ii mesogenic properties of h cn polyesters prepared from 1 4 dialkylesters of Pyromellitic Acid and hydroquinone
Polymer Journal, 1992Co-Authors: Junji Watanabe, Brian R Harkness, Masato SoneAbstract:Rigid-rod polyesters with long alkyl side chains, denoted as H-Cn, have been prepared by reacting 1,4-dialkylesters of Pyromellitic Acid with hydroquinone. The alkyl groups were varied from hexyl (n=6) to octadecyl (n=18). The mesomorphic properties and structure of these polyesters were examined by optical microscopy, DSC and X-ray measurements. The experimental results indicate that the H-Cn polyesters with side-chain lengths of n≥12 exhibit liquid crystalline mesophases with a characteristic layered structure. In this structure, the aromatic main chains in the extended form pack into layers with one-dimensionally positional order in the lateral direction and the alkyl side chains in the disordered form occupy the space between the layers. This layered structure is considered to result from a kind of microphase separation of the aromatic and aliphatic components of the polymer, which results in an unusually observed increase in the isotropization temperatures of liquid crystals with an increase in the side-chain length.
Brian R Harkness - One of the best experts on this subject based on the ideXlab platform.
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rigid rod polyesters with flexible side chains based on 1 4 dialkyl esters of Pyromellitic Acid and 4 4 biphenol 5 high resolution 13c nmr studies for crystalline and liquid crystalline layered phases
Macromolecules, 1994Co-Authors: Masato Sone, Brian R Harkness, Hiromichi Kurosu, Isao Ando, Junji WatanabeAbstract:Rigid-rod aromatic B-Cn polyesters with long alkyl side chains, composed of 1,4-dialkyl esters of Pyromellitic Acid and 4,4'-biphenol, form two distinct types of crystalline phases, K1 and K2, depending on the length of alkyl side chain. These crystalline phases are characterized by a layered structure, in which the aromatic main chains are packed into a layer with the side chains crystallized in the space between the layers. The detailed structures for these two crystalline phases were studied by 13 C solid-state NMR spectroscopy from which it was found that there are remarkable differences in the main-chain conformation and in the packing structure of the side chains
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rigid rod polyesters with flexible side chains 4 thermotropic behavior and phase structures in polyesters based on 1 4 dialkyl esters of Pyromellitic Acid and 4 4 biphenol
Macromolecules, 1994Co-Authors: Junji Watanabe, Brian R Harkness, Masato Sone, Hideo IchimuraAbstract:A series of rigid-rod polyesters with long alkyl side chains, denoted as B-Cn, have been prepared by condensing 1,4-diallyl esters of Pyromellitic Acid with biphenol. The alkyl side-chain lengths were varied from hexyl (n=6) to octedecyl groups (n=18), and the thermotropic transition behavior and mesophase structure of these material were examined by optical microscopy, DSC, and X-ray measurements. An increase in the length of the side chain decreases remarlably the melting point of the crystalline phase, giving rise to a liquid crystalline phase. Two types of liquid crystalline phases with layerlike modifications, LC-1 and LC-2, have been observed. The transition behavior of these liquid crystalline phases is described as a function of the side-chain length
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rigid rod polyesters with flexible side chains based on 1 4 dialkylesters of Pyromellitic Acid ii mesogenic properties of h cn polyesters prepared from 1 4 dialkylesters of Pyromellitic Acid and hydroquinone
Polymer Journal, 1992Co-Authors: Junji Watanabe, Brian R Harkness, Masato SoneAbstract:Rigid-rod polyesters with long alkyl side chains, denoted as H-Cn, have been prepared by reacting 1,4-dialkylesters of Pyromellitic Acid with hydroquinone. The alkyl groups were varied from hexyl (n=6) to octadecyl (n=18). The mesomorphic properties and structure of these polyesters were examined by optical microscopy, DSC and X-ray measurements. The experimental results indicate that the H-Cn polyesters with side-chain lengths of n≥12 exhibit liquid crystalline mesophases with a characteristic layered structure. In this structure, the aromatic main chains in the extended form pack into layers with one-dimensionally positional order in the lateral direction and the alkyl side chains in the disordered form occupy the space between the layers. This layered structure is considered to result from a kind of microphase separation of the aromatic and aliphatic components of the polymer, which results in an unusually observed increase in the isotropization temperatures of liquid crystals with an increase in the side-chain length.
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rigid rod polyesters with flexible side chains based on 1 4 dialkyl esters of Pyromellitic Acid 1
Macromolecules, 1991Co-Authors: Brian R Harkness, Junji WatanabeAbstract:Polyesters [O-Ar-OCO-Ph(COOR) 2 CO] n (Ar= Ph (I), Ph-Ph (II); R= C 14 H 29 ) were prepared and studied. X-ray examination of the mesophases of these polymers showed that they adopt layered structures. Polymer II displays two distinct layerlike modifications which depend on temperature, whereas the mesophase of I assumes a single layered structure that has a greater degree of order than the mesophase of II.
Alexander M Kirillov - One of the best experts on this subject based on the ideXlab platform.
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antiviral antibacterial antifungal and cytotoxic silver i biomof assembled from 1 3 5 triaza 7 phoshaadamantane and Pyromellitic Acid
Molecules, 2020Co-Authors: Sabina W Jaros, Alexander M Kirillov, Jaroslaw Krol, Barbara Bazanow, Dominik Poradowski, Aleksander Chroszcz, Dmytro S Nesterov, Piotr SmolenskiAbstract:The present study reports the synthesis, characterization, and crystal structure of a novel bioactive metal-organic framework, [Ag4(µ-PTA)2(µ3-PTA)2(µ4-pma)(H2O)2]n·6nH2O (bioMOF 1), which was assembled from silver(I) oxide, 1,3,5-triaza-7-phosphaadamantane (PTA), and Pyromellitic Acid (H4pma). This product was isolated as a stable microcrystalline solid and characterized by standard methods, including elemental analysis, 1H and 31P{1H} NMR and FTIR spectroscopy, and single crystal X-ray diffraction. The crystal structure of 1 disclosed a very complex ribbon-pillared 3D metal-organic framework driven by three different types of bridging ligands (µ-PTA, µ3-PTA, and µ4-pma4-). Various bioactivity characteristics of bioMOF 1 were investigated, revealing that this compound acts as a potent antimicrobial against pathogenic strains of standard Gram-negative (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria, as well as a yeast (Candida albicans). Further, 1 showed significant antiviral activity against human adenovirus 36 (HAdV-36). Finally, bioMOF 1 revealed high cytotoxicity toward an abnormal epithelioid cervix carcinoma (HeLa) cell line with low toxicity toward a normal human dermal fibroblast (NHDF) cell line. This study not only broadens the family of PTA-based coordination polymers but also highlights their promising multifaceted bioactivity.
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interplay between h bonding and interpenetration in an aqueous copper ii aminoalcohol Pyromellitic Acid system self assembly synthesis structural features and catalysis
Dalton Transactions, 2018Co-Authors: Tiago A Fernandes, Alexander M Kirillov, Marina V Kirillova, Vânia AndreAbstract:Two new copper(ii) coordination compounds, [Cu(H1.5mdea)2]2(H2pma) (1a) and [{Cu2(μ-Hmdea)2}2(μ4-pma)]n·2nH2O (1b), were self-assembled at different temperatures from the same multicomponent reaction system, comprising copper(ii) nitrate, N-methyldiethanolamine (H2mdea), Pyromellitic Acid (H4pma), and potassium hydroxide. Products 1a and 1b were isolated as microcrystalline solids and fully characterized and their structures were established by single-crystal X-ray diffraction. Compound 1a features the bis-aminoalcohol(ate) monocopper(ii) units and H2pma2- anions that are multiply interconnected by strong H-bonds into a firm 2D H-bonded layer. Compound 1b reveals the bis-aminoalcoholate dicopper(ii) motifs that are interlinked by the μ4-pma4- spacers into a 3D + 3D interpenetrated metal-organic framework. From a topological perspective, both networks of 1a and 1b are uninodal and driven by similar 4-connected H2pma2- or pma4- nodes, but result in distinct sql and dia topologies, respectively. Compound 1a was applied as an efficient catalyst for two model cycloalkane functionalization reactions: (1) oxidation by H2O2 to form cyclic alcohols and ketones and (2) hydrocarboxylation by CO/H2O and S2O82- to form cycloalkanecarboxylic Acids. The substrate scope, effects of various reaction parameters, selectivity and mechanistic features were also investigated.
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copper ii coordination polymers self assembled from aminoalcohols and Pyromellitic Acid highly active precatalysts for the mild water promoted oxidation of alkanes
Inorganic Chemistry, 2016Co-Authors: Tiago A Fernandes, Marina V Kirillova, Vânia Andre, Carla I M Santos, Julia Klak, Alexander M KirillovAbstract:Three novel water-soluble 2D copper(II) coordination polymers-[{Cu2(μ2-dmea)2(H2O)}2(μ4-pma)]n·4nH2O (1), [{Cu2(μ2-Hedea)2}2(μ4-pma)]n·4nH2O (2), and [{Cu(bea)(Hbea)}4(μ4-pma)]n·2nH2O (3)-were generated by an aqueous medium self-assembly method from copper(II) nitrate, Pyromellitic Acid (H4pma), and different aminoalcohols [N,N-dimethylethanolamine (Hdmea), N-ethyldiethanolamine (H2edea), and N-benzylethanolamine (Hbea)]. Compounds 2 and 3 represent the first coordination polymers derived from H2edea and Hbea. All the products were characterized by infrared (IR), electron paramagnetic resonance (EPR), and ultraviolet-visible light (UV-vis) spectroscopy, electrospray ionization-mass spectroscopy (ESI-MS(±)), thermogravimetric and elemental analysis, and single-crystal X-ray diffraction (XRD), which revealed that their two-dimensional (2D) metal-organic networks are composed of distinct dicopper(II) or monocopper(II) aminoalcoholate units and μ4-pyromellitate spacers. From the topological viewpoint, the underlying 2D nets of 1-3 can be classified as uninodal 4-connected layers with the sql topology. The structures of 1 and 2 are further extended by multiple intermolecular hydrogen bonds, resulting in three-dimensional (3D) hydrogen-bonded networks with rare or unique topologies. The obtained compounds also act as highly efficient precatalysts for the mild homogeneous oxidation, by aqueous H2O2 in Acidic MeCN/H2O medium, of various cycloalkanes to the corresponding alcohols and ketones. Overall product yields up to 45% (based on cycloalkane) were attained and the effects of various reaction parameters were investigated, including the type of precatalyst and Acid promoter, influence of water, and substrate scope. Although water usually strongly inhibits the alkane oxidations, a very pronounced promoting behavior of H2O was detected when using the precatalyst 1, resulting in a 15-fold growth of an initial reaction rate in the cyclohexane oxidation on increasing the amount of H2O from ∼4 M to 17 M in the reaction mixture, followed by a 2-fold product yield growth.
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Copper(II) Coordination Polymers Self-Assembled from Aminoalcohols and Pyromellitic Acid: Highly Active Precatalysts for the Mild Water-Promoted Oxidation of Alkanes
2016Co-Authors: Tiago A Fernandes, Marina V Kirillova, Carla I M Santos, Vânia André, Julia Kłak, Alexander M KirillovAbstract:Three novel water-soluble 2D copper(II) coordination polymers[{Cu2(μ2-dmea)2(H2O)}2(μ4-pma)]n·4nH2O (1), [{Cu2(μ2-Hedea)2}2(μ4-pma)]n·4nH2O (2), and [{Cu(bea)(Hbea)}4(μ4-pma)]n·2nH2O (3)were generated by an aqueous medium self-assembly method from copper(II) nitrate, Pyromellitic Acid (H4pma), and different aminoalcohols [N,N-dimethylethanolamine (Hdmea), N-ethyldiethanolamine (H2edea), and N-benzylethanolamine (Hbea)]. Compounds 2 and 3 represent the first coordination polymers derived from H2edea and Hbea. All the products were characterized by infrared (IR), electron paramagnetic resonance (EPR), and ultraviolet–visible light (UV-vis) spectroscopy, electrospray ionization–mass spectroscopy (ESI-MS(±)), thermogravimetric and elemental analysis, and single-crystal X-ray diffraction (XRD), which revealed that their two-dimensional (2D) metal–organic networks are composed of distinct dicopper(II) or monocopper(II) aminoalcoholate units and μ4-pyromellitate spacers. From the topological viewpoint, the underlying 2D nets of 1–3 can be classified as uninodal 4-connected layers with the sql topology. The structures of 1 and 2 are further extended by multiple intermolecular hydrogen bonds, resulting in three-dimensional (3D) hydrogen-bonded networks with rare or unique topologies. The obtained compounds also act as highly efficient precatalysts for the mild homogeneous oxidation, by aqueous H2O2 in Acidic MeCN/H2O medium, of various cycloalkanes to the corresponding alcohols and ketones. Overall product yields up to 45% (based on cycloalkane) were attained and the effects of various reaction parameters were investigated, including the type of precatalyst and Acid promoter, influence of water, and substrate scope. Although water usually strongly inhibits the alkane oxidations, a very pronounced promoting behavior of H2O was detected when using the precatalyst 1, resulting in a 15-fold growth of an initial reaction rate in the cyclohexane oxidation on increasing the amount of H2O from ∼4 M to 17 M in the reaction mixture, followed by a 2-fold product yield growth
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Topologically Unique 2D Heterometallic CuII/Mg Coordination Polymer: Synthesis, Structural Features, and Catalytic Use in Alkane Hydrocarboxylation
2016Co-Authors: Alexander M Kirillov, Matti Haukka, Marina V Kirillova, Yauhen Y. Karabach, Armando J L PombeiroAbstract:The new two-dimensional (2D) heterometallic CuII/Mg coordination polymer [Cu2Mg2(μ-Htea)2(μ6-pma)(H2O)6]n·6nH2O (1) with an unprecedented [Cu2Mg(μ-O)2(μ-COO)2]− core has been easily generated by aqueous medium self-assembly from copper(II) nitrate, triethanolamine (H3tea), magnesium hydroxide, and Pyromellitic Acid (H4pma). The crystal structure of 1 is composed of infinite interdigitated 2D metal–organic layers that extend via H-bonds into an intricate 3D supramolecular framework. The topological analysis of 1 discloses a binodal 2,4-connected underlying 2D net with the unique topology described by the point symbol of (64·8·10)(6), further simplification of which leads to an uninodal 4-connected net with the sql topology. Apart from representing a very rare example of the heterometallic Cu/Mg coordination network, compound 1 also acts as an efficient catalyst precursor for the mild single-pot hydrocarboxylation of linear and cyclic Cn (n = 5–9) alkanes into the corresponding Cn+1 carboxylic Acids
