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A new biomimetic sensor (BS) has been prepared by modifying the carbon paste electrode (CPE) based on [Fe(NTB)Cl2]Cl·EtOH (FeC) {NTB = tris(2‐benzimidazolylmethyl)amine} for the electrochemical detection of acrylamide (AA). The development of the reported BS was focused on the creation of an AA with α‐NH2 group of N‐terminal valine of hemoglobin (HG), which reduces the peak current of HG‐Fe+3 reduction. The fabricated BS was characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV), as well as square wave voltammetry (SWV) for studying the electrochemical properties of AA on its surface. Under optimized conditions, the BS was applied for the direct determination of AA in two linear concentration ranges: 1.0 × 10−6 and 1.0 × 10−4 M. The first linear was observed from 1.0 × 10−6 to 1 × 10−5 M with a limit of detection (LOD) of 1.465 × 10−7 M, while the second linear part was detected from 1.0 × 10−5 to 1 × 10−4 M with LOD of 5.67 × 10−6 M. Finally, the constructed BS was successfully applied for the evaluation of AA in various potato chips, and the results were comparable to those obtained from other electrochemical methods. The density functional theory (DFT) could successfully explain the recognition process of acrylamide, that is, the hydroamination of the alkene group of acrylamide by imidazole moiety of the iron complex. [ABSTRACT FROM AUTHOR]

A set of π‐conjugated copolymers were synthesized via Pd‐catalyzed cross‐coupling based on benzothiadiazole and cyanopyridine moieties along with other π‐bridge units (thiophene and/or benzene). Their chemical structures were confirmed by various analytical techniques (elemental, IR, 1H, and 13C NMR analyses). All copolymers showed good solubility in most common organic solvents. Thermogravimetric analysis (TGA) analysis showed their good thermal stability with no significant weight loss up to ~260°C. The estimated optical band gaps for thin films were found to be in the range of 2.25–2.62 eV. It was found that the π‐bridge units (benzene and/or thiophene) significantly affect the molecular architecture and optoelectronic properties of the copolymers. They exhibited good fluorescence in diluted solution where the fluorescence emission spectra were obtained by irradiative excitation at the wavelength in the range of 526.0–532.0 nm. X‐ray diffraction (XRD) revealed that all copolymers exhibited a symmetric halo peak at 2θ = 22.5–23.8° corresponding to the presence of alkyl side chains in addition to a small intensity peak at 2θ of ~43° indicates the existence of some degree of remnant some ranges of crystallinity in the films. Density functional theory (DFT) and time‐dependent DFT (TD‐DFT) calculations were used to assess planarity, electronic structure, and optical absorption properties. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) at the molecular mechanical level and geometry optimisation at the quantum mechanical level have been performed to investigate the transport and fixation of oxygen and carbon dioxide in the cavity of ribulose-1,5-bisphosphate carboxylase/oxygenase, or Rubisco. Multiple MD simulations have been carried out to study the diffusive behaviour of O2 and CO2 molecules from the Mg2+ cation in Rubisco at 298 K and 1 bar, being one step in the overall process of carboxylation/oxygenation in Rubisco. In addition to this work, in order to gain additional perspective on the role of chemical reaction rates and thermodynamics, oxygen, and carbon dioxide uptake mechanisms have also been investigated by the aid of quantum chemical calculations. The results indicate that the activation barrier for carboxylation is slightly lower than that of oxygenation. This agrees qualitatively with experimental findings, and rationalises the observed competition between both catalytic processes in nature. Finally, the longer-lived persistence of CO2 in the vicinity of the active centre (i.e., slower self-diffusion) may serve to explain, in part, why carboxylation is the more kinetically favoured on an overall basis compared to oxygenation. [ABSTRACT FROM AUTHOR]

A template Schiff condensation of 2,6‐pyridine dicarbaldehyde or 2,6‐diformyl‐4‐ bromophenol and 1,3–diamino‐2‐hydroxy propane or 3,4‐diaminotoluene in the presence of copper(II) salts (CuX2) (X = Cl, Br, CH3COO, or ClO4) affords different types of copper(II) complexes. Depending on the employed molar ratio of the dicarbonyl compounds and diamines, different types of copper(II) complexes formed during the template condensation reaction. Structural formulation of the complexes was confirmed by elemental analysis (C, H, N, and M), physical measurements such as thermal analysis (TAG & DTG), molar conductivity, and magnetic moments in addition to spectral studies (UV–Vis, IR, and ESR). Homobinuclear in a four‐coordinate square planar and five‐coordinate square pyramidal and trigonal bipyramidal in monomeric structures are proposed. A mononuclear hexa‐coordinate in an octahedral geometry is suggested as well. Oxidase biomimetic catalytic activity of these newly synthesized copper(II) complexes was examined toward the aerobic oxidation of 4‐tert‐butylcatechol (4‐TBCH2) and o‐aminophenol under catalytic conditions. Both catalytic and kinetic investigations demonstrate promising oxidase catalytic activity and based on the kinetic results, probable mechanistic catalytic implications are discussed. Geometrical structures of representative copper(II) complexes were determined by optimizing their bond lengths, bond angles, dihedral angles, and the structural index (τ). [ABSTRACT FROM AUTHOR]

Iodine-catalyzed condensation of 2-amino-3,5-dibromobenzamide with cyclohexane-1,3-dione derivatives in refluxing toluene afforded the corresponding bisquinazolinones. Suzuki-Miyaura cross-coupling of the latter with arylboronic acids afforded tetraarylbisquinazolinones. The electronic absorption and emission properties of these tetraarylbisquinazolinones were measured in dimethylsulfoxide (DMSO) and acetic acid by means of UV-Vis and fluorescence spectroscopic techniques in conjunction with quantum chemical methods to understand the influence of substituents on intramolecular charge transfer (ICT). [ABSTRACT FROM AUTHOR]

The 2-aryl-6,8-dibromo-4-chloroquinazolines derived from the 2-aryl-6,8- dibromoquinazolin-4(3H)-ones were subjected to the Sonogashira cross-coupling with terminal acetylenes at room temperature to afford novel 2-aryl-6,8-dibromo-4- (alkynyl)quinazoline derivatives. Further transformation of the 2-aryl-6,8-dibromo-4- (phenylethynyl)quinazolines via Suzuki-Miyaura cross-coupling with arylboronic acids occurred without selectivity to afford the corresponding 2,6,8-triaryl-4- (phenylethynyl)quinazolines. The absorption and emission properties of these polysubstituted quinazolines were also determined. [ABSTRACT FROM AUTHOR]

Using density functional theory (DFT) methods, we have investigated two possible mechanisms for atmospheric CO2 fixation in the cavity of the dinuclear zinc(II) octa-azacryptate, and the subsequent reaction with methanol whereby this latter reaction transforms the (essentially) chemically inert CO2 into useful products. The first mechanism (I) was proposed by Chen et al. [Chem.-Asian J.2007, 2, 710], and involves the attachment of one CO2 molecule onto the hydroxyl-cryptate form, resulting in the formation of a bicarbonate-cryptate species and subsequent reaction with one methanol molecule. In addition, we suggest another mechanism that is initiated via the attachment of a methanol molecule onto one of the Zn-centers, yielding a methoxy-cryptate species. The product is used to activate a CO2 molecule and generate a methoxycarbonate-cryptate. The energy profiles of both mechanisms were determined, and we conclude that, while both mechanisms are energetically feasible, free energy profiles suggest that the scheme proposed by Chen et al. is most likely. [ABSTRACT FROM AUTHOR]