Carbonyl Units Research Articles

Metal Organic Framework‐Derived Cobalt Dicarboxylate as a High‐Capacity Anode Material for Lithium‐ion Batteries

AbstractConsiderable attention has been paid to metal‐organic frameworks (MOFs) for applications as electrode materials for lithium‐ion batteries recently. In this study, we use cobalt terephthalate CoC8H4O4 (CoTPA), one type of MOFs, as an anode material for lithium‐ion batteries for the first time. It delivers a high discharge capacity of about 700 mAh g−1 after 100 cycles with superior capacity retention. In contrast to the conventional lithium‐storage mechanism of MOF‐based anodes in organic carbonyl units, both the inorganic unit (Co2+) and the organic unit (carbonyl group) offer multi‐electron transfer reactions, which results in such a high capacity.

Core-shell materials bearing iron(ii) carbonyl units and their CO-release via an upconversion process.

CO-release induced by near infrared (NIR) light, to which body tissues are relatively transparent, from photoactive CO-releasing molecules (PhotoCORMs) has great significance in exploring the clinical potential of CO. In this work, a novel upconversion nanoparticle-based nanoplatform, UCNPs@SiO2-CORMs, has been developed using a one-pot reaction. The materials liberate CO under the irradiation of NIR light. TEM images of the materials showed that this nanoplatform consisted of a core-shell structure. On the surface were incorporated thiol groups through which mono-iron(ii) carbonyl units, "Fe(η5-Cp)(CO)2" were successfully anchored by a ligand exchange reaction between [Fe(η5-Cp)(CO)2I] (1) and the thiol groups. The core of the materials consists of β-NaYF4:Yb3+/Er3+ upconversion nanoparticles (UCNPs). Strong emission bands around 530 and 550 nm from the materials upon irradiation by NIR fall into the broad band of the electronic spectrum of the materials. Consequently, the constructed nanoplatform steadily released CO upon irradiation with a 980 nm laser (1 W cm-2). Kinetic analysis suggests that CO-release from UCNPs@SiO2-CORMs in DMSO/D2O media fits a zero-order reaction model. Assessment of the cytotoxicity of UCNPs@SiO2-CORMs indicated that they showed excellent biocompatibility and no significant photo-toxicity.

A stereodynamic phosphoramidite ligand derived from 3,3'-functionalized ortho-biphenol and its rhodium(I) complex.

Stereodynamic ligands and complexes bearing functional groups to attach chiral or achiral binding sites and auxiliaries are highly attractive due to the interesting opportunities for controlling the stereochemical outcome of enantioselective transformations. In this study we report the preparation of a 3,3'-functionalized biphenol (BIPOL) phosphoramidite ligand (PAm ) bearing 3,5-dichlorobenzoyl (3,5-DCB) amide binding sites for noncovalent interactions. Upon coordination to [Rh(COD)2 ]BF4 this substitution pattern directs one of the 3,5-DCB binding sites in close proximity of the metal center resulting in liberation of both COD ligands and the formation of a [Rh(PAm )2 ]BF4 complex. Coordination of the amide carbonyl unit was found to be reversible, since the complex acted as an active catalyst in the hydrogenation of dehydroamino acid derivatives. X-ray crystallographic investigation revealed that the second 3,5-DCB unit is capable of forming noncovalent π-π interactions connecting both phosphoramidite ligands.

Polymers functionalized with 1,2-benzenedithiolate-bridged model compound of [FeFe]-hydrogenase: Synthesis, characterization and their catalytic activity

Three polymers functionalized with 1,2-benzenedithiolate-bridged diiron carbonyl units, Polymers 1–3, were prepared by using three diazide monomers with different organic frames via “click chemistry”. These polymers were characterized by IR spectroscopy, thermal gravimetric analysis, scanning electron microscopy and electrochemistry. Their solubility, morphology and catalysis on proton reduction are largely controlled by the organic moieties of the diazides. The presence of carboxylates in Polymer 3 causes significant difference both physically and chemically (electrochemically). It is soluble in water but decomposes rapidly in DMSO. Its stability is much improved after being assembled into membrane electrodes. The electrodes assembled from these polymers are relatively robust and all operational in water. The carboxylate in Polymer 3 turns out a better proton-relay in catalysis by exhibiting higher catalytic efficiency in both solution and solid state (membrane electrode).

Thermal stability, solubility, and fluorescence property of poly(arylene vinylene ketone)s bearing 1,1′-binaphthylene units

Mizoroki–Heck coupling polymerization of diiodonated 1,1′-binaphthyls (BINTL1/BINTL2) with 1,4-divinylbenzenes (DVB-H/DVB-Me/DVB-OMe) proceeded to afford poly(arylene vinylene ketone)s (PAVK1–6). Upon photoexcitation, PAVKs in solutions exhibit fluorescence behavior with large Stokes shifts, and the maximum emission wavelength (λem) depends on the nature of the solvent. PAVK1 analogs, in which the ketone carbonyl units of PAVK1 are replaced by sulfone, methylene, and ketal ones, were synthesized. Fluorescence spectra of PAVK1 analogs clearly exhibit a blue shift from that of original PAVK1. The difference in behavior between PAVKs and PAVK1 analogs suggests that the fluorescence of PAVKs originates from donor–acceptor interaction between 1,4-distryrylbenzene skeletons and ketone carbonyl units, respectively.

Novel formazan derivatives containing phenylsulfanyl and carbonyl units: synthesis, optical and electrochemical properties

New phenylsulfanyl and aryl carbonyl containing formazan derivatives4a–4hand5a–5hhave been developed, and investigated the effect of substituents on their photophysical and electrochemical properties.

Spherulitic morphologies of the triblock Poly(GL)-b-poly(GL-co-TMC-co-CL)-b-poly(GL) copolymer: Isothermal and non-isothermal crystallization studies

Crystallization of a biodegradable segmented copolymer constituted by polyglycolide hard segments and a middle soft segment constituted by a random disposition of glycolyl, ε-caproyl and trimethylene carbonyl units has been studied by means of optical microscopy, atomic force microscopy and time resolved X-ray diffraction techniques. This Poly(GL)-b-poly(GL-co-TMC-co-CL)-b-poly(GL) copolymer is widely employed as surgical suture and has similar characteristics than previously studied copolymers having a middle soft segment constituted by only two monomers (i.e. glycolide and trimethylene carbonate).FTIR and NMR spectroscopies demonstrated that the middle segment had an amorphous character and a random microstructure as consequence of transesterification reactions that took place during synthesis. Nevertheless, polyglycolide segments were able to crystallize giving rise to peculiar positive birefringent spherulites with a morphology, which depends on crystallization temperature (i.e. flat-on and edge-on crystals) as verified by AFM and electron diffraction patterns.Complete bell shaped curves that defined the temperature dependence of the crystal growth rate could be experimentally obtained from both, isothermal and non-isothermal crystallizations. Data from both analyses were in close agreement and pointed out a secondary nucleation constant (2.42–2.88×105K2) which was clearly higher than that determined for the related system with two components. Lamellar morphologic parameters were similar for samples crystallized from the melt state and after the reordering process that took place on heating. Comparing to the bicomponent system, significant differences were again observed highlighting the influence of the soft segment on the crystallization behavior.

Reactivity of 1,2,3-triselena[3]ferrocenophane towards transition metal carbonyls

Reactions of 1,2,3-triselena[3]ferrocenophane with [Mn2(CO)10], [Fe(CO)5] and [Os3(CO)12] have been investigated under photolytic or thermolytic conditions. Clusters with contrasting structures have been isolated from these reactions: [{Fe(η-C5H4Se)2Mn(CO)3}2] (1), [Fe(η-C5H4Se)2Fe2(CO)6] (2), [Fe(η-C5H4Se)2Os3(CO)10] (3), [Fe(η-C5H4Se)2(μ2-Se)Os2(CO)6] (4) and [Fe(η-C5H4Se)2(μ3-Se)Os4(CO)11] (5). Formally, these new clusters are formed by substitution of the central selenium of 1,2,3-triselena[3]ferrocenophane by metal carbonyl units, as in 1–3 or insertion of two Os(CO)3 groups or an Os4(CO)11 unit into the Se–Se bond as in 4 and 5, respectively.

Well-Balanced Carrier Mobilities in Ambipolar Transistors Based on Solution-Processable Low Band Gap Small Molecules

We synthesized a solution-processable low band gap small molecule, Si1TDPP-EE-COC6, for use as a semiconducting channel material in organic thin film transistors (OTFTs). The Si1TDPP-EE-COC6 is composed of electron-rich thiophene–dithienosilole–thiophene (Si1T) units and electron-deficient diketopyrrolopyrrole (DPP) and carbonyl units. SiTDPP-EE-COC6-based OTFTs with Au source/drain electrodes were fabricated, and their electrical properties were systematically investigated with increasing thermal annealing temperature. The hole and electron mobilities of as-spun Si1TDPP-EE-COC6 were 3.3 × 10–4 and 1.7 × 10–4 cm2 V–1 s–1, respectively. The carrier mobilities increased significantly upon thermal annealing at 150 °C, yielding a hole mobility of 0.003 cm2 V–1 s–1 and an electron mobility of 0.002 cm2 V–1 s–1. The performance enhancement upon thermal annealing was strongly associated with the formation of a layered edge-on structure and a reduction in the π–π intermolecular spacing. Importantly, the use of at...

Formal Aryne/Carbon Monoxide Copolymerization To Form Aromatic Polyketones/Polyketals

A palladium-catalyzed alternating copolymerization of [2.2.1]oxabicyclic alkenes 1 with carbon monoxide afforded isomer mixtures of polyketones 2ktn and polyketals 2ktl. Subsequent acid-induced dehydration of polymer 2 furnished novel aromatic polymers consisting of polyketones 3ktn and polyketals 3ktl units. This formal aryne/carbon monoxide copolymerization thus generated the first example of poly(aryne-alt-carbon monoxide)s, in which o-arylene and carbonyl units are incorporated in an alternating fashion.

Synthetic studies of alkaloids containing pyrrolidine and piperidine structural motifs.

Awarding Institute: Goa University (India) Date awarded: December, 2013 Supervisor: Prof. Santosh G. Tilve, HOD Chemistry, Goa University, Goa (India)

Identification of heme oxygenase-1 stimulators by a convenient ELISA-based bilirubin quantification assay

The upregulation of heme oxygenase-1 (HO-1) has proven to be a useful tool for fighting inflammation. In order to identify new HO-1 inducers, an efficient screening method was developed which can provide new lead structures for drug research. We designed a simple ELISA-based HO-1 enzyme activity assay, which allows for the screening of 12 compounds in parallel in the setting of a 96-well plate. The well-established murine macrophage cell line RAW264.7 is used and only about 26µg of protein from whole cell lysates is needed for the analysis of HO-1 activity. The quantification of HO-1 activity is based on an indirect ELISA using the specific anti-bilirubin antibody 24G7 to quantify directly bilirubin in the whole cell lysate, applying a horseradish peroxidase-tagged antibody together with ortho-phenylenediamine and H2O2 for detection. The bilirubin is produced on the action of HO enzymes by converting their substrate heme to biliverdin and additional recombinant biliverdin reductase together with NADPH at pH 7.4 in buffer. This sensitive assay allows for the detection of 0.57–82pmol bilirubin per sample in whole cell lysates. Twenty-three small molecules, mainly natural products with an α,β-unsaturated carbonyl unit such as polyphenols, including flavonoids and chalcones, terpenes, an isothiocyanate, and the drug oltipraz were tested at typically 6 or 24h incubation with RAW264.7 cells. The activity of known HO-1 inducers was confirmed, while the chalcones cardamonin, flavokawain A, calythropsin, 2′,3,4′-trihydroxy-4-methoxychalcone (THMC), and 2′,4′-dihydroxy-3,4-dimethoxychalcone (DHDMC) were identified as new potent HO-1 inducers. The highest inductive power after 6h incubation was found at 10µM for DHDMC (6.1-fold), carnosol (3.9-fold), butein (3.1-fold), THMC (2.9-fold), and zerumbone (2.5-fold). Moreover, the time dependence of HO-1 protein production for DHDMC was compared to its enzyme activity, which was further evaluated in the presence of lipopolysaccharide and the specific HO-1 inhibitor tin protoporphyrin IX. Taken together, we developed a convenient and highly sensitive ELISA-based HO-1 enzyme activity assay, allowing the identification and characterization of molecules potentially useful for the treatment of inflammatory and autoimmune diseases.

Highly Efficient and Eco-Friendly Gold-Catalyzed Synthesis of Homoallylic Ketones

We report a new catalytic protocol for the synthesis of γ,δ−unsaturated carbonyl units from simple starting materials, allylic alcohols and alkynes, via a hydroxalkoxylation/Claisen rearrangement sequence. This new process is more efficient (higher TON and TOF) and more eco-friendly (increased mass efficiency) than the previous state-of-the-art technique. In addition, this method tolerates both terminal and internal alkynes. Moreover, computational studies have been carried out in order to shed light on how the Claisen rearrangement is initiated.

The 19S Deubiquitinase Inhibitor b-AP15 Is Enriched in Cells and Elicits Rapid Commitment to Cell Death

b-AP15 [(3E,5E)-3,5-bis[(4-nitrophenyl)methylidene]-1-(prop-2-enoyl)piperidin-4-one] is a small molecule inhibitor of the ubiquitin specific peptidase (USP) 14/ubiquitin carboxyl-terminal hydrolase (UCH) L5 deubiquitinases of the 19S proteasome that shows antitumor activity in a number of tumor models, including multiple myeloma. b-AP15 contains an α,β-unsaturated carbonyl unit that is likely to react with intracellular nucleophiles such as cysteine thiolates by Michael addition. We found that binding of b-AP15 to USP14 is partially reversible, and that inhibition of proteasome function is reversible in cells. Despite reversible binding, tumor cells are rapidly committed to apoptosis/cell death after exposure to b-AP15. We show that b-AP15 is rapidly taken up from the medium and enriched in cells. Enrichment provides an explanation of the stronger potency of the compound in cellular assays compared with in vitro biochemical assays. Cellular uptake was impaired by 30-minute pretreatment of cells with low concentrations of N-ethylmaleimide (10 µM), suggesting that enrichment was thiol dependent. We report that in addition to inhibition of deubiquitinases, b-AP15 inhibits the selenoprotein thioredoxin reductase (TrxR). Whereas proteasome inhibition was closely associated with cell death induction, inhibition of TrxR was not. TrxR inhibition is, however, likely to contribute to triggering of oxidative stress observed with b-AP15. Furthermore, we present structure-activity, in vivo pharmacokinetic, and hepatocyte metabolism data for b-AP15. We conclude that the strong enrichment of b-AP15 in cells and a rapid commitment to apoptosis/cell death are factors that likely contribute to the strong antitumor activity of this compound.

Synthesis, Characterization, and X‐ray Crystal Structures of Ru3(CO)9(dppm)AsPh3 and Ru3(CO)9(dpam)PPh3 Complexes

Abstract Clusters Ru3(CO)10(dppm) and Ru3(CO)10(dpam) on reaction with AsPh3 and PPh3 in refluxing n‐hexane afford trisubstituted clusters Ru3(CO)9(dppm)AsPh3 and Ru3(CO)9(dpam)PPh3, respectively. These two trisubstituted clusters are characterized by spectroscopic and single‐crystal X‐ray diffraction. Ru3(CO)9(dppm)AsPh3 and Ru3(CO)9(dpam)PPh3 show a triangle of ruthenium atoms, in which the bidentate and monodentate group 15 ligands occupy equatorial position and all the carbonyl units are terminally bonded. The Ru–Ru distances in Ru3(CO)9(dppm)AsPh3 are 2.8461(7) Å, 2.8495(7) Å, and 2.8930(6) Å, with the longest distance cis to the monodentate AsPh3 ligand. For Ru3(CO)9(dpam)PPh3, the Ru–Ru distances are 2.8652(2) Å, 2.8809(2) Å, and 2.8560(2) Å with the longest distance also cis to the monodenatate PPh3 ligand.

Assembling chiral salan–copper(II) complexes into a 2D-network with carboxylic acid functionalization

In this work, we aim to assemble a polymeric copper(II) network by ligand modifications with carboxylic acid functional groups. A chiral, reduced salen ligand, salan R,R-H21 with pendant ester functionalities has been synthesized. Its copper(II) complex, [Cu(R,R-1)], has been isolated, and its crystal structure determined by X-ray crystallography. Hydrolysing the ester groups of R,R-H21 to carboxylic acids yields R,R-H42 as the hydrochloride salt R,R-H42·2HCl. Treatment of R,R-H42·2HCl with copper(II) acetate in the presence of triethylamine yields the complex [Cu(R,R-H22)]n and X-ray structural analysis reveals that this consists of a 2D polymeric network. Each copper(II) center is bound within the near square-planar N2O2 donor set of the Schiff base ligand [R,R-H22]2− and pendant carboxylic acid groups of adjacent units coordinate through the CO2H carbonyl units in the axial sites of the copper ion to complete an axially distorted octahedral coordination environment. The sheets are stacked via interdigitation of the cyclohexyl domains, giving an overall porous assembly containing carboxylic acid functionalities. This has proven to be an effective strategy for adding the dimensionality of metal–organic complexes by carboxylic acid functionalization of ligands.

Homogeneous Cyclocarbonylation of Alkenols with Iron Pentacarbonyl

We report substantially improved reaction conditions for palladium(II)-catalyzed tandem cyclization–intramolecular oxycarbonylation of (amino)polyols with a terminal double bond, based on utilization of iron pentacarbonyl [Fe(CO)₅] as an affordable and safe liquid supply of the carbonyl unit fully replacing gaseous carbon monoxide. Direct comparison with the classical version on a series of previously published substrates illustrates invariably shorter reaction times but comparable yields and selectivity.

Fast and Efficient 18F‐Labeling by [18F]Fluorophenylazocarboxylic Esters

Introduction of [(18) F]fluoride ion into the aromatic core of phenylazocarboxylic esters was achieved in only 30 seconds, with radiochemical yields of up to 95 % (85(±10) %). For labeling purposes, the resulting (18) F-substituted azoester can be further converted in radical-arylation reactions to give biaryls, or in substitutions at its carbonyl unit to produce azocarboxamides.

Opening or Closing the Lock? When Reactivity Is the Key to Biological Activity

Thiol-mediated processes play a key role to induce or inhibit inflammation proteins. Tailoring the reactivity of electrophiles can enhance the selectivity to address only certain surface cysteines. Fourteen 2',3,4,4'-tetramethoxychalcones with different α-X substituents (X=H, F, Cl, Br, I, CN, Me, p-NO2-C6H4, Ph, p-OMe-C6H4, NO2, CF3, COOEt, COOH) were synthesized, containing the potentially electrophilic α,β-unsaturated carbonyl unit. The assessment of their reactivity as electrophiles in thia-Michael additions with cysteamine shows a change in the reactivity of more than six orders of magnitude. Moreover, a clear correlation between their reactivity and an influence on the inflammation proteins heme oxygenase-1 (HO-1) and the inducible NO synthase (iNOS) is demonstrated. As the biologically most active compound, the α-CF3 -chalcone is shown to inhibit the NO production in RAW264.7 mouse macrophages in the nanomolar range.

ChemInform Abstract: Mukaiyama Aldol Reaction of Trimethylsilyl Enolate with Aldehyde Catalyzed by CuI.

Mukaiyama aldol reaction is an efficient methodology for carbon-carbon bond formation reaction 1 . This reaction between enolsilane derivatives and aldehydes provides a route for the stereoselective construction of β-hydroxy carbonyl units which are important building blocks for the construction of many natural products and pharmaceuticals. Since the discovery of the reaction by Mukaiyama, promoted by TiCl4 (ref. 2), a variety of catalysts have been used to activate this process 3 . Many of the catalysts have limitations such as use of stoichiometric amount of catalyst, moisture sensitivity of the catalyst, expensive reagents, etc. Although many recent reports claimed improvement of the process eliminating those drawbacks, new methods are still desirable. Li and coworkers reported the use of MgI2.Et2O as catalyst for aldol reactions 3k . But this method again has the drawback of the requirement of dry reaction medium. Apart from the Lewis acids, Lewis bases were also employed for Mukaiyama aldol reaction 4 . Recently, N-methylimidazole was found to be a good catalyst for aldol reaction between trimethylsilyl ketene acetal and aldehyde 4h . However, this method requires extra addition of LiCl as a promoter. Use of Cu(OTf)2 in presence of various ligands has also been reported by various researchers for such transformations 5 . But Cu(OTf)2 is expensive and moisture sensitive. Due to the selectivity associated with this versatile process, there is a thrust in this area to develop new catalysts to make the process more simple, economic and effective. The use of copper catalyst in organic transformations is more advantageous because it is cheap and relatively benign. CuI has emerged as a very effective catalyst for various organic transformations. In continuation of the work on CuI catalysed reactions 6 , herein is reported the Mukaiyama aldol reaction of silyl keten acetal with various aldehydes (Scheme I).