CO NH Research Articles

Experimental FTIR and theoretical investigation of the molecular structure and vibrational spectra of acetanilide using DFT and dispersion correction to DFT

The FTIR spectrum of acetanilide (ACN) is recorded and analyzed. The optimized molecular structures, harmonic vibrational wavenumbers and corresponding vibrational assignments of the ACN are computationally examined by using the B3LYP density functional theory method together with the standard 6-311[Formula: see text]G([Formula: see text],[Formula: see text]) basis set. From the calculations, the ACN is predicted to exist predominantly in trans configuration with the relative energy, rotational barrier, and population of 2.8[Formula: see text]kcal/mol, 14.8[Formula: see text]kcal/mol, and 99.5%, respectively. The optimized structure shows that the amide group (CO–NH) of trans-ACN adopts a planar peptide-like conformation. The effect of the incorporation of dispersion correction to the B3LYP on the calculated equilibrium structure and vibrational spectra of ACN is investigated. The highest occupied and the lowest unoccupied molecular orbitals, IR intensities and molecular electrostatic potential results are reported. In addition, reliable vibrational assignments have been made on the basis of Potential Energy Distribution (PED) using VEDA4 program. Simulated IR spectrum are compared with the experimental FTIR and FT-Raman spectra. Energy decomposition analysis (EDA) revealed that Pauli repulsion is responsible for the increased stability of the trans over the cis isomer.

Adsorption Behavior of Iodine by Novel Covalent Organic Polymers Constructed Through Heterostructural Mixed Linkers

The efficient capture and storage radioactive iodine (129I or 131I) formed during the extensive use of nuclear energy is of paramount importance. In this work, we presented a novel covalent organic polymer (JLUE-COP-3) constructed through heterostructural mixed linkers with perforated porousness, plenty of π-conjugated phenyl rings and functional –CO–NH– and –SO3H groups to iodine adsorption process. After fully characterizing the morphology and structure, the adsorption behavior of iodine by the resultant polymers were explored in detail. The external adsorption behavior was determined to obey the pseudo-second order kinetic model according to the kinetic analysis. The maximum liquid adsorption capacity was obtained to reach 153.85 mg/g at 298 K, which was evaluated by the Langmuir isotherm model. In addition, the negative attributes of ΔGo as well as the positive attributes of ΔHo and ΔSo at three temperatures, indicated the nature of the iodine adsorption over JLUE-COP-3 was spontaneous and endothermic.

Site‐Selective Arylation of Naphthalenes: a Key Entry towards Extended Fluorenones and Phenanthridinones

The development of an oriented arylation process dedicated to the naphthalene core is presented. Our approach is based on dual role of N‐tosyl carboxamides acting jointly as a directing group in a first C–H arylation step and as a “CO” or “CO–NH” fragment precursor in a further construction step of naphthalene‐based fluorenone or phenanthridinone derivatives. The presence of the directing group in position 1 and 2 of the naphthalene platform allowed selective arylations in position 2 and 3 respectively. Our study represents a first synthetic and general entry of C–H arylation at naphthalene platforms towards the preparation of extended fluorenones as well as benzo‐fused phenanthridinones. Further, the C–H arylation and cyclisation sequence represents a useful way to the preparation of novel extended tetra‐ and pentacyclic fluorenones bearing both electron donating as well as electron withdrawing groups in various substitution patterns. Additionally, both the regioselectivity and the reaction paths of the cyclization leading to the fluorenone architectures was studied by DFT calculations which fully complement experimental observations.

Two neoteric pyrazole compounds as potential anti-cancer agents: Synthesis, electronic structure, physico-chemical properties and docking analysis

The pyrazole derivatives, (E)-4-(2-(3-chlorophenyl)hydrazono)-5-methyl-2,4-dihydro-3H-pyrazol-3-one (CPHMP) and 4-(2-(2,4,5-trichlorophenyl)hydrazinyl)-2,4-dihydro-3H-pyrazol-3-one (TCPHP) were synthesized and identified using LCMS (ESI-MS), C H N elemental and NMR analysis. Using FT-IR and FT-Raman spectra were recorded and compared with theoretically simulated spectra and found that both of them agrees with each other. The oscillator strength of CPHMP is sufficiently large which makes it an ideal candidate to use as a photo sensitizer in photo voltaic systems. First hyperpolarizabilities of CPHMP and TCPHP are 94.04 and 50.52 times that of urea. From the MEP plot the active sites are determined and CO group and NH moiety are the most electrophilic and nucleophilic regions for both the pyrazole derivatives. Docking studies propose that CPHMP and TCPHP might reveal negative response against human microsomal prostaglandin E synthase 1.

Synthesis and glutathione reductase inhibitory properties of 5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one's aryl Schiff base derivatives.

Glutathione reductase (GR) is responsible for the existence of the reduced glutathione (GSH) molecule, a crucial antioxidant against oxidative stress reagents. The antimalarial activities of some redox active compounds are attributed to their inhibition of antioxidant flavoenzyme GR, and inhibitors are therefore expected to be useful for the treatment of malaria. In this work, a fast and effective synthesis and the GR inhibitory properties of 5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one's aryl Schiff base derivatives are reported. For this aim, the triazol nucleus was obtained, which was substituted with identical groups: ester, hydrazide, and Schiff base system at the N-2 and N-4 nitrogen atoms. The majority of the reactions were carried out by utilizing both microwave and conventional methods in order to compare their yields and reaction times. Beside this, the occuring E/Z geometrical isomers from the CN double bond and the cis/trans amide conformers at the CONH single bond were studied. In the biological activity section of this work, it was found that all synthesized compounds have better inhibitory activity than N,N-bis(2-chloroethyl)-N-nitrosourea against GR; especially, two molecules, 6e and 6f, are the best among them. The evidence indicates that these Schiff base derivatives, with triazole ring, are strong GR inhibitors and novel antimalaria candidates.

Enhanced water resistance and energy performance of core–shell aluminum nanoparticles via in situ grafting of energetic glycidyl azide polymer

The application of aluminum nanoparticle is limited due to its passivation Al2O3 layer even though it owns extreme specific surface and high reaction activity. In this work, the aluminum nanoparticles were modified via in situ grafting onto energetic glycidyl azide polymer (GAP) to improve the stability and energy-releasing performance. The results showed that GAP was grafted on the nano-aluminum surface with chemical bonds of –O–(CO–NH)– formed, and the thickness of shell layer of GAP could be tuned by changing the relative ratio of reactants. Furthermore, modified nanoparticles show hydrophobicity with static water contact angle changing from 20.2° to 142.4°. Significant increasing stability of aluminum nanoparticles is obtained in hot water, which is evidenced by that around 10 wt% of modified aluminum is reacted after 210 min. Based on the core–shell configurations, (Al@GAP)/fluorine composites were prepared. The violent combustion phenomenon and high release rate profiles revealed high energy-releasing performance with the assistance of GAP. This synthetic strategy may provide an effective approach to prepare other metal nanoparticles, and possess potential application value in the fields of metallized explosives and high-energy structure with energy release.

A domino knoevenagel-phospha-michael reaction: One-pot synthesis of novel organophosphonates in the presence of multi-walled carbon nanotube‒CO‒NH(CH2)2NH-SO3H as catalyst

GRAPHICAL ABSTRACT

Role of hydrogen bonding in establishment of a crystalline network of Cu (II) complex with hydrazone-derived ligand: optoelectronic studies

For the first time, a new Cu(II) complex including pyrazine (pyz) and a tridentate O,N,O–donor hydrazone ligand formulated as Cu(L)(pyz)(CH3OH)]+ (1) (LH=[CF3C(OH)=CH–C(CH3)=N–NH–CO–C6H4(OH)]) (CuClC 17 H 18 F 3 N 4 O 4 ) has been investigated using density functional theory (DFT) methods. The DFT approaches have been performed by applying B3LYP/LANL2DZ/6–311 + G(d, p) and full potential linearized augmented plane wave (FP–LAPW) methods. The complex belongs to triclinic crystallographic system with space group of P1, Z = 2. Selected 1 as monomeric unit (1-mon) through a variety of non-covalent interactions containing hydrogen bonds (HBs) and π-stacking, constructs a 2-D coordination polymeric plane. The dispersion corrected density functional theory (DFT-D) calculations indicate that the conventional O–H···N and the non-conventional C–H···F HBs, govern the related network (1-net) formation. The calculated-B3LYP/LANL2DZ/6–311 + G(d, p) electronic spectrum in gas phase in good agreement with the experimental one shows five major bands in the range of 268–582 nm that could be assigned to MLCT and LLCT transitions with n → π* character. Calculated optoelectronic spectra by FP–LAPW show that Cu–3d state play key role in optical transitions and plasma wavelength of 243 nm found for this studied compound.

The role of topically applied l-ascorbic acid in ex-vivo examination of burn-injured human skin

Wound treatment and healing is complex and is comprised of an elaborate set of processes including cellular, spectroscopic and biochemical ones as well as the “reaction” of local tissue to thermal injury. Vitamin C as l-ascorbic acid (LA) prevents injurious effects of oxidants because it reduces reactive oxygen species to stable molecules, it becomes oxidized to the short-lived ascorbyl radical. As a result, antioxidant treatment may contribute to minimizing injury in burn patients. The aim of this study is to assess changes in molecular structure of collagen extracted from human epidermis burn wound scab during incubation of the epidermis in l-ascorbic acid solution. The study will be performed using FTIR and FT Raman spectroscopies. During this research it was observed that the intensity of Raman peaks increased where healing was being modified by LA. The intensity of the amide III band at 1247cm−1 relative to the intensity at 1326cm−1 was used to test tissue repair degree at the incision site. FTIR spectra were recorded from frozen specimens of serum modified by LA; an analysis of shifts in the amide I band position was conducted. The appearance of a new band for frozen samples modified by LA was observed around 1149–1220cm−1. The above conclusions confirmed the creation of hydrogen bonds between NH stretch and CO. Samples being incubated in solutions of l-ascorbic acid demonstrated the absence of electrophoretic bands of albumin. Alterations in the surface of the skin incubated in l-ascorbic acid were investigated with the use of Scanning Electron Microscopy (SEM). A decrease in external symptoms of burn injury was noted in the damaged epidermis incubated in l-ascorbic acid.

The Complexation between Amide Groups of Polyamide‐6 and Polysulfides in the Lithium–Sulfur Battery

Lithium–sulfur batteries have attracted considerable attention due to its high theoretical specific capacity, low cost, environmental friendliness, etc. However, the dissolution of polysulfide intermediate in the electrolyte leads to rapid capacity decay in the charge–discharge process. A sulfur‐based cathode with the specific discharge capacity of 630 mAh g−1 and ultrahigh capacity retention ratio of 0.11% per cycle after 400 cycles at 0.5 C that simply blend the sublimed sulfur and acetylene black in the mortar with the polyamide‐6 (PA6) as binder is reported. The intense complexation between the lithium polysulfide and amide groups (CONH) in PA6 can effectively inhibit the “shuttling effect” and reduce the loss of active materials during the charge–discharge process. The discovery provides a handy and practicable strategy for developing the excellent cycling stability lithium–sulfur batteries. image

Effects of methylene diphenyl diisocyanate on the physical, mechanical, and vulcanization properties of nitrile rubber

ABSTRACTIn this research, methylene diphenyl diisocyanate (MDI) was added to an acrylonitrile–butadiene rubber (NBR) compound as an additive, and its effects on the vulcanization of the rubber investigated. For this purpose, MDI was added at different concentrations (5, 10, and 20 phr) to the rubber compound. The rubber properties, including the rheometry and tensile strength, were investigated. Differential scanning calorimetry and swelling tests were used to assess the vulcanization mechanism and chemical reactions in the presence of MDI. Finally, Fourier transform infrared spectroscopy analysis was used to study the chemical structure of the NBR–MDI cured compounds. We found that MDI played a more important role than the additive in the NBR compound. It acted as a covulcanizing agent along with the sulfur groups. The 10 phr MDI content was found to be the optimum content for achieving the best NBR–MDI properties. This content increased the crosslinking density of the compound and decreased the swelling of NBR in toluene. We also found that MDI adsorbed the accelerator agents and sulfur groups, so it decreased the rate of vulcanization, especially at early ages. Furthermore, it reacted with NBR and produced strong urea (i.e., NHCONH) and thiourethane groups (i.e., SCONH), and this increased NBR's structural strength. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45200.

Di‐ and Tetranuclear Palladium(II) Complexes Containing C,N‐Bidentate Furoylhydrazone for Suzuki–Miyaura Reactions

Furoylhydrazones of general formula 4‐R–C6H4–CH=NNH–CO–2‐C4H3O [R = H (HL1) and OCH3 (HL2)] have been conveniently prepared from furan‐2‐carbohydrazide. The reaction of HL1 with Li2[PdCl4] and CH3COONa provided the di‐µ‐chloro‐bridged cyclopalladated complex [Pd(C6H4–CH=N–NH–CO–2‐C4H3O)(µ‐Cl)]2 (1) through aryl C–H bond activation, whereas the unusual tetranuclear cluster [Pd(4‐CH3O–C6H4–CH=N–NH–CO–2‐C4H3O)(µ‐Cl)]4 (2) was obtained from the reaction with ligand HL2. The crystal structures of 1 and 2 show a slightly distorted square‐planar coordination geometry around the palladium ion to which the furoylhydrazone is attached in a bidentate fashion. The two palladium(II) complexes were able to catalyze the Suzuki–Miyaura coupling reactions of phenylboronic acid with aryl halides to afford the desired biaryl derivatives in excellent yields (up to 99.2 %).

Assembly of anion-controlled cadmium(II) coordination polymers from the use of 2-acetyl-pyridyl-isonicotinoylhydrazone

Four Cd(II) coordination polymers have been synthesized, utilizing a tetradentate pyridine-based Schiff base ligand, namely 2-acetyl-pyridyl-isonicotinoylhydrazone (HL), and different anions (CH3COO−, N3−, SCN−). The products {[Cd2(L)2(CH3COO)2]·C2H5OH}n (1), {[Cd1.5(L)(CH3COO)(N3)(H2O)]·C2H5OH}n (2), {[Cd(HL)(SCN)2]·CH3OH}n (3) and [Cd3(HL)2(SCN)6]n (4), were characterized with single-crystal X-ray diffraction, IR spectroscopy, and luminescence studies. The ligand in 1 and 2 is singly-deprotonated and coordinates to the cadmium centre in the enolic form (N–NC–O) while in compounds 3 and 4 it coordinates in its neutral keto form (N–NH–CO). The tetradentate ligand in 2 acts as a linker and leads to the formation of a one-dimensional coordination polymer. The CH3COO− in 1 and SCN− in 3 and 4, further act as bridges, forming two-dimensional coordination polymers (1 and 3) and a three-dimensional network (4). Structural diversity is thus induced by the anions, due to the variable steric hindrance they impose as well as differing bridging capacity; metal-organic network formation is also evident via different Van der Waals forces.

The Development of a Portable SPR Bioanalyzer for Sensitive Detection of Escherichia coli O157:H7.

The purpose of this study was to develop a portable surface plasmon resonance (SPR) bioanalyzer for the sensitive detection of Escherichia coli O157:H7 in comparison with an enzyme-linked immunosorbent assay (ELISA). The experimental setup mainly consisted of an integrated biosensor and a homemade microfluidic cell with a three-way solenoid valve. In order to detect Escherichia coli O157:H7 using the SPR immunoassay, 3-mercaptopropionic acid (3-MPA) was chemisorbed onto a gold surface via covalent bond for the immobilization of biological species. 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) were used as crosslinker reagents to enable the reaction between 3-MPA and Escherichia coli O157:H7 antibodies by covalent –CO–NH– amide bonding. The experimental results were obtained from the Escherichia coli O157:H7 positive samples prepared by 10-, 20-, 40-, 80-, and 160-fold dilution respectively, which show that a good linear relationship with the correlation coefficient R of 0.982 existed between the response units from the portable SPR bioanalyzer and the concentration of Escherichia coli O157:H7 positive samples. Moreover, the theoretical detection limit of 1.87 × 103 cfu/mL was calculated from the positive control samples. Compared with the Escherichia coli O157:H7 ELISA kit, the sensitivity of this portable SPR bioanalyzer is four orders of magnitude higher than the ELISA kit. The results demonstrate that the portable SPR bioanalyzer could provide an alternative method for the quantitative and sensitive determination of Escherichia coli O157:H7 in field.

Chiral lactate-modified silica aerogels

Silica-based aerogels containing L-lactic moiety were synthesized by a cogelation procedure of tetramethoxysilane (TMOS) with lactate-modified aminopropyltrimethoxysilane L-CH3CH(OH)CO–NH–(CH2)3Si(OMe)3, followed by supercritical drying (SCD). Lactate-modified silica aerogels are semi-transparent yellowish monoliths possessing high specific surface area (up to 340 m2/g). L-lactate-containing lyogel and aerogel possess the optical activity inherent to L-lactic acid derivatives.

Far-infrared amide IV-VI spectroscopy of isolated 2- and 4-Methylacetanilide.

Delocalized molecular vibrations in the far-infrared and THz ranges are highly sensitive to the molecular structure, as well as to intra- and inter-molecular interactions. Thus, spectroscopic studies of biomolecular structures can greatly benefit from an extension of the conventional mid-infrared to the far-infrared wavelength range. In this work, the conformer-specific gas-phase far-infrared spectra of two aromatic molecules containing the peptide -CO-NH- link, namely, 2- and 4-Methylacetanilide, are investigated. The planar conformations with trans configuration of the peptide link have only been observed in the supersonic-jet expansion. The corresponding far-infrared signatures associated with the vibrations of the peptide -CO-NH- moiety, the so-called amide IV-VI bands, have been assigned and compared with the results of density functional theory frequency calculations based on the anharmonic vibrational second-order perturbation theory approach. The analysis of the experimental and theoretical data shows that the amide IV-VI bands are highly diagnostic for the geometry of the peptide moiety and the molecular backbone. They are also strongly blue-shifted upon formation of the NH⋯O-C hydrogen bonding, which is, for example, responsible for the formation of secondary protein structures. Furthermore, the amide IV-VI bands are also diagnostic for the cis configuration of the peptide link, which can be present in cyclic peptides. The experimental gas-phase data presented in this work can assist the vibrational assignment of similar biologically important systems, either isolated or in natural environments.

A novel method to bind soybean protein onto the surface of poly(ethylene terephthalate) fabric

In this study, –NH2 groups were introduced to a poly(ethylene terephthalate) (PET) fabric to make the fabric hydrophilic and, then, soybean protein was bonded on the surface of the modified PET fabric to obtain a soybean protein/PET composite fabric. The –NH2 groups allowed the soybean protein to be firmly bonded on the surface of the modified PET fabric. Scanning electron microscopy images showed that the surface of each modified PET fiber had a small number of grooves and that there was a thin film on each soybean protein/PET fiber. Attenuated total reflectance Fourier transform infrared spectra demonstrated that the nitrated and reduced PET fibers were introduced –NH2 groups and that there were –CO–NH– groups on the surface of soybean protein/PET fibers. X-ray photoelectron spectroscopy analyses showed that there was a nitrogen element on the modified PET fibers. The X-ray diffraction patterns suggested that the crystal structures of the modified fibers did not change significantly during the modification processes. The thermogravimetry results showed that the thermal stability of soybean protein/PET fiber kept well. The wearability tests indicated that the breaking strength and elasticity of the original fabric were well retained by the modified fabrics. The soybean protein/PET fabric had good levels of hydrophilicity and softness when the binding rate was below 3.0%.

Design of hybrid PVA–CA–Jania rubens biomatrix for removal of lead

ABSTRACTPolyvinyl alcohol–sodium alginate (PVA–SA) matrix was fabricated and red algae Jania rubens was embedded for removal of lead from aqueous solutions. The Pb(II) uptake rate was rapid primarily at 1 h and equilibrium was achieved within 2 h. The optimum pH was 5, the data were well fitted by Langmuir and Freundlich models, and RL values are in the range of 0.1–0.38. The sorption capacity (qe) of PVA–calcium alginate (CA)–J. rubens matrix increased from 10.77 to 37.195 mg g−1 with increasing Pb(II) concentration from 24.86 to 98.75 mg L−1 at the temperature of 30°C and pH 5. The sorption capacity (qe) and maximum biosorption (qm) were noted as 37.179 ± 0.32 and 71.43 mg/g, respectively. The adsorption process was well described by pseudo-second-order model. The reaction is endothermic, is spontaneous, and increases in randomness. The functional groups present on matrix, i.e., –OH, –C–N, –C–O,–CO–NH, –NH2, –SH, and –C–OH, were intensely involved in the process. Scanning electron microscopy results revealed the morphological changes due to adsorption of Pb(II) on and inside of PVA–CA–J. rubens matrix. Desorption study indicates the efficient regeneration of PVA–CA–J. rubens biomass matrix for three cycles and is a promising matrix for removal of Pb(II) and can be used in continuous systems.

Synthesis, X-ray characterization, DFT calculations and Hirshfeld surface analysis of Zn(ii) and Cd(ii) complexes based on isonicotinoylhydrazone ligand

In this manuscript we report the synthesis and X-ray characterization of four Zn(II) complexes and three Cd(II) complexes with an asymmetrical hydrazone–pyridine based ligand {HL = 2-acetyl-pyridyl-isonicotinoylhydrazone (HAPIH)}; i.e. {[Zn(HL)2](NO3)2·H2O} (1), [Zn(HL)Br2] (2), [Zn(HL)I2] (3), [Zn(HL)(NCS)2] (4), [Cd(L)2] (5), {[Cd(HL)Br2]·CH3OH} (6) and {[Cd(HL)I2]·2CH3OH} (7). The Schiff base acts as a tridentate N2O-donor ligand through the oxygen, the imine and pyridine nitrogen atoms in all the complexes. In most complexes, the ligand is observed to coordinate as a zwitterion since the proton in the hydrazine group (N–NH–CO) shifted to the uncoordinated pyridine ring, except in 7. On the other hand, in 5 the ligand acts as a negatively charged species and is bound to the cadmium center in the enolic form (N–NC–O−). In complexes 2–4, 6 and 7, the coordination geometry around each metal center is distorted trigonal bipyramidal, with the coordination sphere of the metal completed by two halide or NCS anions. On the other hand, in homoleptic complexes 1 and 5, the metal, chelated by two tridentate Schiff base ligands, exhibits an octahedral geometry. In the crystal packing of all compounds, the pyridine rings favour π–π interactions among the symmetry related complexes. The noncovalent interactions among the complexes have been analyzed using Hirshfeld surface analysis and DFT calculations using Grimme's D3 dispersion correction to properly describe the π–π interactions.

Synthesis and thermal investigation by TG–FTIR–MS analysis of some functionalized acrylic copolymers and magnetic composites with Fe3O4

The synthesis of some acrylic crosslinked copolymers based on divinyl benzene, ethyl acrylate and acrylonitrile as such, or functionalized with triethylenetetramine by aminolysis reaction has been studied. Also, the magnetic composites obtained in situ with Fe3O4 nanoparticles, are presented. The magnetite amount included in the copolymer matrix, calculated from the resulting residue at thermal degradation was 9–10wt.%. The thermal stability and evolved gas analysis were examined by thermogravimetry coupled with Fourier transform infrared spectroscopy and mass spectrometry. TG–FTIR–MS analysis revealed that different gaseous species were detected during the heating process of the copolymers: water, carbon dioxide, carbon monoxide, ammonia, ketones and alkyl, aromatic, amine derivatives. The thermal stability of the aminolysed copolymer is lower, because beside the existing ester linkages in the initial copolymer structure other chemical bonds by the aminolysis reaction have appeared, such as HC–NH or CO–NH less thermally stable.