Nitrile Functional Groups Research Articles

Using Nitrile Functional Groups to Replace Amines for Solution-Deposited Single-Walled Carbon Nanotube Network Films

Amine-terminated self-assembled monolayers (SAMs) can be utilized to selectively adsorb semiconducting single-walled carbon nanotubes (S-SWNTs), but are not ideal. Formation of these monolayer films from silanes can be dramatically influenced by atmospheric and other processing conditions, resulting in poor-quality SAMs or irreproducible results. The surface sorting method of fabricating these semiconducting nanotube networks (SWNTnts) can become ineffective if the functionalized surface is not smooth with high amine density. However, by replacing the amine with a nitrile group, SAM formation can be made more controllable and reproducible. Upon SWNT deposition, the nitrile group was found to not only adsorb higher density SWNTnts but also sort the nanotubes efficiently, as shown by micro-Raman spectroscopy. Upon testing these SWNTnts for device performance, these thin-film transistors (TFTs) were also found to yield higher quality devices than those fabricated on amine surfaces. Overall, these results expand the applicability of surface sorting and SWNT adsorption to other organic functionalities for nanotube separation. This report provides an outline of the merits and characterization of using the nitrile functional group for the separation and adsorption of SWNTs and its integration in network TFTs.

An effective approach to enhance temperature independence of dielectric properties for polyarylene ether nitrile films

A series of crosslinked polyarylene ether nitrile films with different crosslink densities were prepared by using 4,4′-bis(3,4-dicyanophenoxy)biphenyl as a novel crosslinking agent. The crosslinking reaction was described as the thermally induced cyclotrimerization of the nitrile functional groups to the stable sym-triazines. After thermal crosslinking, the microstructure has been changed from a microscopic phase-separation system to a homogeneous system. The glass transition temperature and 5% weight loss temperature were increased up to 181°C and 484°C, respectively. More importantly, the temperature independence of both dielectric constant and dielectric loss was dramatically improved by the crosslinking, and the dielectric properties were found to be relatively stable with respect to temperature before the turning point temperature, which is very near to the glass transition temperature.

New synthesis of multisubstituted cyanocyclopropanes by the intramolecular SN2 alkylation and 1,3-CC insertion reaction of magnesium carbenoids as the key reactions

Addition reaction of 1-chlorovinyl p-tolyl sulfoxides derived from ketones and aldehydes with lithium α-cyano carbanions gave nitrile adducts in high to quantitative yields. Treatment of the nitrile adducts derived from acetonitrile with excess i-PrMgCl in THF resulted in the formation of cyanocyclopropanes via the intramolecular SN2 alkylation of the generated magnesium carbenoids. The intermediate of this reaction was proved to be a cyclopropylmagnesium chloride and was reactive with electrophiles to give multisubstituted cyanocyclopropanes. On the other hand, the reaction of the nitrile adducts derived from arylacetonitriles with i-PrMgCl resulted in the formation of 2-arylcyanocyclopropanes by the 1,3-carbon–carbon (1,3-CC) insertion reaction of the generated magnesium carbenoid intermediates. This reaction was found to proceed in a highly stereospecific manner. The key reactions, intramolecular SN2 alkylation and 1,3-CC insertion reaction of the magnesium carbenoids, are the first examples for the reaction of the magnesium carbenoids bearing a nitrile functional group.

Reaction of InCl3with Various Reducing Agents: InCl3–NaBH4-Mediated Reduction of Aromatic and Aliphatic Nitriles to Primary Amines

While alternative methods of preparing dichloroindium hydride (HInCl(2)) via the in situ reduction of InCl(3) using lithium amino borohydride (LAB) were explored, generation of HInCl(2) from the reduction of InCl(3) by sodium borohydride (NaBH(4)) was also re-evaluated for comparison. The reductive capability of the InCl(3)/NaBH(4) system was found to be highly dependent on the solvent used. Investigation by (11)B NMR spectroscopic analyses indicated that the reaction of InCl(3) with NaBH(4) in THF generates HInCl(2) along with borane-tetrahydrofuran (BH(3)·THF) in situ. Nitriles underwent reduction to primary amines under optimized conditions at 25 °C using 1 equiv of anhydrous InCl(3) with 3 equiv of NaBH(4) in THF. A variety of aromatic, heteroaromatic, and aliphatic nitriles were reduced to their corresponding primary amine in 70-99% isolated yields. Alkyl halide and nitrile functional groups were reduced in tandem by utilizing the reductive capabilities of both HInCl(2) and BH(3)·THF in a one-pot reaction. Finally, the selective reduction of the carbon bromine bond in the presence of nitriles was achieved by generating HInCl(2) via the reduction InCl(3) with NaBH(4) in CH(3)CN or with lithium dimethylaminoborohydride (MeLAB) in THF.

Synthesis and characterization of poly(hydroxamic acid)–poly(amidoxime) chelating ligands from polymer‐grafted acacia cellulose

AbstractGraft copolymerization of methyl acrylate (MA) and acrylonitrile (AN) onto acacia cellulose was carried out using free radical initiating process in which ceric ammonium nitrate (CAN) was used as an initiator. The optimum grafting yield was determined by the certain amount of acacia cellulose (AGU), mineral acid (H2SO4), CAN, MA, and AN at 0.062, 0.120, 0.016, 0.397, and 0.550 mol L−1, respectively. The poly(methyl acrylate‐co‐acrylonitrile)‐grafted acacia cellulose was obtained at 55°C after 2‐h stirring, and purified acrylic polymer‐grafted cellulose was characterized by FTIR and TG analysis. Therein, the ester and nitrile functional groups of the grafted copolymers were reacted with hydroxylamine solution for conversion into the hydroxamic acid and amidoxime ligands. The chelating behavior of the prepared ligands toward some metal ions was investigated using batch technique. The metal ions sorption capacities of the ligands were pH dependent, and the sorption capacity toward the metal ions was in the following order: Zn2+ > Fe3+ > Cr3+ > Cu2+ > Ni2+. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

ChemInform Abstract: Acylation of Grignard Reagents Mediated by N‐Methylpyrrolidone: A Remarkable Selectivity for the Synthesis of Ketones.

An efficient user-friendly method of acylation of Grignard reagents to selectively synthesize ketones is presented, which is assisted by simple amides such as NMP, or DMF. The present chemoselective method tolerates a variety of functional groups such as ketone, ester, nitrile and other functional groups.

Monoamine oxidase inhibition by C4-substituted phthalonitriles

It was recently reported that a series of C5-substituted phthalimides are remarkably potent reversible inhibitors of recombinant human monoamine oxidase (MAO) B. Modeling studies suggested that the phthalimide ring forms numerous polar interactions with the polar region of the MAO-B substrate cavity while the C5 side chain extends to, and interacts via Van der Waals interactions with the hydrophobic regions of the enzyme entrance cavity. Interactions with both cavities appear to be requirements for high affinity binding. In the present study we have examined an analogs series of C4-substituted phthalonitriles as potential human MAO inhibitors. The phthalonitriles were found to be highly potent reversible MAO-B inhibitors with most analogs exhibiting IC50 values in the low nM range. The phthalonitriles also interacted with human MAO-A, although with lower binding affinities compared to MAO-B. Modeling studies suggest that the high binding affinities of the phthalonitriles to MAO-B may depend, at least in part, on the formation of polar interactions between the nitrile functional groups and the enzyme substrate cavity. Examination of a homologs series of benzonitriles established that the phthalonitrile moiety is more optimal for MAO-B inhibition than the corresponding benzonitrile moiety, and that C3-substituted benzonitriles are better MAO-B inhibitors than C4-substituted benzonitriles. Since elimination of the nitrile functional group yielded compounds with only moderate MAO-B inhibition potencies, it may be concluded that this functional group is privileged for MAO-B inhibition.

Light Activation of a Cysteine Protease Inhibitor: Caging of a Peptidomimetic Nitrile with RuII(bpy)2

A novel method for caging protease inhibitors is described. The complex [Ru(II)(bpy)(2)(1)(2)](PF(6))(2) (2) was prepared from the nitrile-based peptidomimetic inhibitor Ac-Phe-NHCH(2)CN (1). (1)H NMR, UV-vis, and IR spectroscopic and mass spectrometric data confirmed that 2 equiv of inhibitor 1 bind to Ru(II) through the nitrile functional group. Complex 2 shows excellent stability in aqueous solution in the dark and fast release of 1 upon irradiation with visible light. As a result of binding to the Ru(II) center, the nitriles of complex 2 are caged, and 2 does not act as a potent enzyme inhibitor. However, when 2 is irradiated, it releases 1, which inhibits the cysteine proteases papain and cathepsins B, K and L up to 2 times more potently than 1 alone. Ratios of the IC(50) values in the dark versus in the light ranged from 6:1 to 33:1 for inhibition by 2 against isolated enzymes and in human cell lysates, confirming that a high level of photoinduced enzyme inhibition can be obtained using this method.

Preparation of Hydrolyzed Electrospun Polyacrylonitrile Fiber Mats as Chelating Substrates: A Case Study on Copper(II) Ions

Ultrafine polyacrylonitrile (PAN) fiber mats were prepared by electrospinning and subsequently hydrolytically treated with a sodium hydroxide ethanolic/aqueous solution to impart the ability to chelate metal ions. This was achieved through the conversion of the nitrile functional groups on the surface of the PAN fibers into imine conjugated sequences, which was confirmed by Fourier-transform infrared spectroscopy. The chelating property of the hydrolyzed electrospun PAN fiber mats (i.e., H-ePAN fiber mats) was evaluated against Cu(II) ions. The amounts of the Cu(II) ions adsorbed onto the H-ePAN fiber mats were influenced by the initial pH and the initial concentration of the metal ion solutions. At the optimal pH of 5.0, the amounts of the Cu(II) ions adsorbed onto the H-ePAN fiber mats increased with an initial increase in the time the materials were in contact with the metal ion solution to finally reach the maximal, plateau values after about 5 h of immersion. The maximal adsorption capacity of the H-...

Zinc‐Catalyzed Chemoselective Reduction of Tertiary and Secondary Amides to Amines

General and convenient procedures for the catalytic hydrosilylation of secondary and tertiary amides under mild conditions have been developed. In the presence of inexpensive zinc catalysts, tertiary amides are easily reduced by applying monosilanes. Key to success for the reduction of the secondary amides is the use of zinc triflate and disilanes with dual Si-H moieties. The presented hydrosilylations proceed with excellent chemoselectivity in the presence of sensitive ester, nitro, azo, nitrile, olefins, and other functional groups, thus making the method attractive for organic synthesis.

Monoamine oxidase inhibition by selected anilide derivatives

A series of anilide derivatives were synthesized and evaluated as inhibitors of recombinant human monoamine oxidase (MAO) A and B. The most potent inhibitors among the derivatives that were initially evaluated were (2 E)-N-(3-chlorophenyl)-3-phenylprop-2-enamide ( 2c) and (2 E)-N-(3-bromophenyl)-3-phenylprop-2-enamide ( 2d) with IC 50 values of 0.53 μM and 0.45 μM, respectively. These derivatives exhibited reversible and selective inhibition of MAO-B with binding affinities 37 fold higher for MAO-B than for MAO-A. Analysis of the possible binding interactions of these inhibitors with active site models of human MAO-A and –B led to the design of phenolic and benzonitrile derivatives of 2c and 2d. Among these were (2E)-N-(3-chlorophenyl)-3-(4-hydroxyphenyl)prop-2-enamide ( 7c) and (2E)-N-(3-bromophenyl)-3-(4-hydroxyphenyl)prop-2-enamide ( 7d) which inhibited MAO-B selectively and reversibly with IC 50 values of 0.032 μM and 0.026 μM, respectively. These inhibitors were at least 14 fold more potent than 2c and 2d. This study concludes that N,3-diphenylprop-2-enamide is a suitable scaffold for the design of selective MAO-B inhibitors and structural modifications to enhance the binding affinities of the inhibitors for the MAO-B active site include substitution with halogens on the N-phenyl ring and substitution with hydroxyl and nitrile functional groups on the para and meta positions, respectively, of the C3 phenyl ring. Possible binding modes of these structures within the MAO-B active site are proposed with the emphasis on the interactions of the inhibitor halogens and the hydroxyl and nitrile functional groups with active site residues and water molecules.

Nitrile-Functionalized Pyridinium, Pyrrolidinium, and Piperidinium Ionic Liquids

Two series of 1-alkylpyridinium and N-alkyl-N-methylpiperidinium ionic liquids functionalized with a nitrile group at the end of the alkyl chain have been synthesized. Structural modifications include a change of the alkyl spacer length between the nitrile group and the heterocycle of the cationic core, as well as adding methyl or ethyl substituents on different positions of the pyridinium ring. The anions are the bromide and the bis(trifluoromethylsulfonyl)imide ion. All the bis(trifluoromethylsulfonyl)imide salts as well as the bromide salts with a long alkyl spacer were obtained as viscous liquids at room temperature, but some turned out to be supercooled liquids. In addition, pyrrolidinium and piperidinium ionic liquids with two nitrile functions attached to the heterocyclic core have been prepared. The crystal structures of seven pyridinium bis(trifluoromethylsulfonyl)imide salts are reported. Quantum chemical calculations have been performed on model cations and ion pairs with the bis(trifluoromethylsulfonyl)imide anion. A continuum model has been used to take solvation effects into account. These calculations show that the natural partial charge on the nitrogen atom of the nitrile group becomes more negative when the length of the alkyl spacer between the nitrile functional group and the heterocyclic core of the cation is increased. Methyl or methoxy substituents on the pyridinium ring slightly increase the negative charge on the nitrile nitrogen atom due to their electron-donating abilities. The position of the substituent (ortho, meta, or para) has only a very minor effect on the charge of the nitrogen atom. The (15)N NMR spectra of the bis(trifluoromethylsulfonyl)imide ionic liquids were recorded with the nitrogen-15 nucleus at its natural abundance. The chemical shift of the (15)N nucleus of the nitrile nitrogen atom could be correlated with the calculated negative partial charge on the nitrogen atom.

P-glycoprotein Substrate Models Using Support Vector Machines Based on a Comprehensive Data set

P-glycoprotein (P-gp) is one of the major ABC transporters and involved in many essential processes such as lipid and steroid transport across cell membranes but also in the uptake of drugs such as HIV protease and reverse transcriptase inhibitors. Despite its importance, reliable models predicting substrates of P-gp are scarce. In this study, we have built several computational models to predict whether or not a compound is a P-gp substrate, based on the largest data set yet published, employing 332 distinct structures. Each molecule is represented by ADRIANA.Code, MOE, and ECFP_4 fingerprint descriptors. The models are computed using a support vector machine based on a training set which includes 131 substrates and 81 nonsubstrates that were evaluated by 5-, 10-fold, and leave-one-out (LOO) cross-validation. The best model gives a Matthews Correlation Coefficient of 0.73 and a prediction accuracy of 0.88 on the test set. Examination of the model based on ECFP_4 fingerprints revealed several substructures which could have significance in separating substrates and nonsubstrates of P-gp, such as the nitrile and sulfoxide functional groups which have a higher frequency in nonsubstrates than in substrates. In addition structural isomerism in sugars was found to result in remarkable differences regarding the likelihood of a compound to be a substrate for P-gp.

Synthesis of novel ionic liquid ([C4CNmim]+PF6 −) and application to preparation of polyketone

N-valeronitrile-N′-methylimidazolium hexafluorophosphate ([C4CNmim]+PF6−), as a novel ionic liquid with polar nitrile functional group, was prepared. The structure of the ionic liquid was characterized by using IR and 1H NMR. As a medium, the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St). Some synthetic conditions were determined, including the usage of ionic liquid, palladium composite catalyst and methanol, CO pressure, reaction time and reaction temperature. The influence of these factors on catalytic activity was analyzed. The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition: composite catalyst 0.015 mmol, ionic liquid 3 mL, methanol 0.75 mL, CO pressure 2 MPa, reaction time 2 h and reaction temperature 70 °C. This CO/St copolymerization within [C4CNmim]+PF6− system could facilitate ionic liquids with efficient and economical applications to polymeric materials.

The physical and chemical properties of plasma treated ultra-high-molecular-weight polyethylene fibers

A uniform and smooth transfer of stresses across the polymer matrix/fiber interface is enhanced when adhesion between the matrix and fiber surface is optimized. In the absence of covalent bonds matching the Hansen solubility (cohesion) parameters (HSP) of the fiber surface with the HSP of a matrix polymer assures maximum physical adhesion to transfer loads uniformly. Plasma treatment of ultra-high-molecular-weight polyethylene (UHMWPE) fibers is shown to significantly increase the amount of oxygen in the surface. There are two distinct types of surfaces in both the plasma treated and the untreated UHMWPE fibers. One type is typical of polyethylene (PE) polymers while the other is characteristic of the oxygenated surface at much higher values of HSP. The oxygenated surface of the plasma treated fibers has the HSP δ D, δ P, and δ H equal to 16.5, 15.3, and 8.2, compared to the pure PE surface with HSP at 18.0, 1.2, and 1.4, all in MPa ½. The dispersion parameter has been lowered somewhat by the plasma treatment, while the polar and hydrogen bonding parameters are much higher. The HSP methodology predicts enhanced adhesion is possible by skillful use of anhydride and nitrile functional groups in matrix or tie polymers to promote compatibility in the system.

Vibrational Stark Effect Spectroscopy at the Interface of Ras and Rap1A Bound to the Ras Binding Domain of RalGDS Reveals an Electrostatic Mechanism for Protein−Protein Interaction

Electrostatic fields at the interface of the Ras binding domain of the protein Ral guanine nucleotide dissociation stimulator (RalGDS) with the structurally analogous GTPases Ras and Rap1A were measured with vibrational Stark effect (VSE) spectroscopy. Eleven residues on the surface of RalGDS that participate in this protein-protein interaction were systematically mutated to cysteine and subsequently converted to cyanocysteine in order to introduce a nitrile VSE probe in the form of the thiocyanate (SCN) functional group. The measured SCN absorption energy on the monomeric protein was compared with solvent-accessible surface area (SASA) calculations and solutions to the Poisson-Boltzmann equation using Boltzmann-weighted structural snapshots from molecular dynamics simulations. We found a weak negative correlation between SASA and measured absorption energy, indicating that water exposure of protein surface amino acids can be estimated from experimental measurement of the magnitude of the thiocyanate absorption energy. We found no correlation between calculated field and measured absorption energy. These results highlight the complex structural and electrostatic nature of the protein-water interface. The SCN-labeled RalGDS was incubated with either wild-type Ras or wild-type Rap1A, and the formation of the docked complex was confirmed by measurement of the dissociation constant of the interaction. The change in absorption energy of the thiocyanate functional group due to complex formation was related to the change in electrostatic field experienced by the nitrile functional group when the protein-protein interface forms. At some locations, the nitrile experiences the same shift in field when bound to Ras and Rap1A, but at others, the change in field is dramatically different. These differences identify residues on the surface of RalGDS that direct the specificity of RalGDS binding to its in vivo binding partner, Rap1A, through an electrostatic mechanism.

Highly Chemo‐ and Regioselective Reduction of Aromatic Nitro Compounds Catalyzed by Recyclable Copper(II) as well as Cobalt(II) Phthalocyanines

AbstractCopper/cobalt phthalocyanines were established for the first time as catalysts for the very efficient chemo‐ and regioselective reduction of aromatic nitro compounds to generate the corresponding amines. The selective reduction of nitro compounds was observed in the presence of a large range of functional groups such as aldehyde, keto, acid, amide, ester, halogen, lactone, nitrile and heterocyclic functional groups. Furthermore, the present method was found to be highly regioselective towards the reduction of aromatic dinitro compounds in a short time with high yields. In most of the cases the conversion and selectivity were >99% as monitored by GC‐MS. The reduction mechanism was elucidated by UV‐vis and electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry.

Molecular Design of Functionalized m-Poly(phenylene ethynylene) Foldamers: from Simulation to Synthesis

m-Poly(phenylene ethynylene)s (mPPEs) are a class of synthetic molecules being used for biocide coatings, catalysis, as well as chemical and biomolecule sensing because they exhibit a propensity to form a helical secondary structure in solution. Additionally, the folding of mPPEs into such helical arrangements may generally be controlled by varying the primary structure of the mPPE and/or the nature of the solvent. As such, several attempts have been made at developing heuristics for predicting a priori whether a particular mPPE will fold into a helix in a given solvent based on energetic and structural considerations. However, the experimental evidence shows that the formation of helical structures by mPPEs cannot be reliably predicted using such simple models. In this work, we demonstrate that replica-exchange molecular dynamics (REMD) simulations provide excellent agreement with experimental observations. We have simulated 20 different mPPE variations in five different solvent environments. Experimental results are available for eight of these one hundred systems, and in all eight of these cases the REMD results were in agreement with the experiments. Additionally, we simulated and then synthesized two previously unreported mPPEs having both ester and nitrile functional groups. After studying their folding behaviors in chloroform and acetonitrile, it was found that experimental results were in agreement with our predictions. This illustrates how REMD simulations, which are easily carried out with publicly available software on most modern computing systems, can be used to guide synthesis efforts focused on the formation of macromolecules with specific secondary structures.

Isotopic anomalies in organic nanoglobules from Comet 81P/Wild 2: Comparison to Murchison nanoglobules and isotopic anomalies induced in terrestrial organics by electron irradiation

Nanoglobules are a form of organic matter found in interplanetary dust particles and primitive meteorites and are commonly associated with 15N and D isotopic anomalies that are suggestive of interstellar processes. We report the discovery of two isotopically-anomalous organic globules from the Stardust collection of particles from Comet 81P/Wild 2 and compare them with nanoglobules from the Murchison CM2 meteorite. One globule from Stardust Cometary Track 80 contains highly aromatic organic matter and a large 15N anomaly (δ 15N = 1120‰). Associated, non-globular, organic matter from this track is less enriched in 15N and contains a mixture of aromatic and oxidized carbon similar to bulk insoluble organic material (IOM) from primitive meteorites. The second globule, from Cometary Track 2, contains non-aromatic organic matter with abundant nitrile ( C N) and carboxyl ( COOH) functional groups. It is significantly enriched in D (δD = 1000‰) but has a terrestrial 15N/ 14N ratio. Experiments indicate that similar D enrichments, unaccompanied by 15N fractionation, can be reproduced in the laboratory by electron irradiation of epoxy or cyanoacrylate. Thus, a terrestrial origin for this globule cannot be ruled out, and, conversely, exposure to high-energy electron irradiation in space may be an important factor in producing D anomalies in organic materials. For comparison, we report two Murchison globules: one with a large 15N enrichment and highly aromatic chemistry analogous to the Track 80 globule and the other only moderately enriched in 15N with IOM-like chemistry. The observation of organic globules in Comet 81P/Wild 2 indicates that comets likely sampled the same reservoirs of organic matter as did the chondrite parent bodies. The observed isotopic anomalies in the globules are most likely preserved signatures of low temperature (<10 K) chemistry in the interstellar medium or perhaps the outer regions of the solar nebula. In other extraterrestrial samples, D isotopic anomalies, but not those of 15N, may be explained in part by exposure to ionizing electron radiation.

Highly processible maleimide and nitrile functionalized benzoxazines for advanced composites applications

AbstractMaleimide and 2‐aminobenzonitrile (MIan)‐based benzoxazine has been synthesized and characterized. MIan contains imide, oxazine, and nitrile functional groups that can react almost simultaneously, leading to complicated reaction mechanisms. For understanding the fundamental polymerization mechanism, the model benzoxazine compound is synthesized. The ortho‐nitrile group in the model compound undergoes cyclization reaction, producing the thermally stable six‐membered ring species resulting in the excellent thermal properties of the material. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010