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ABSTRACT Chemical investigation of the Liuweizhiji Gegen‐Sangshen oral liquid afforded one new diphenyl ether derivative (1), together with one known compound (2). Their structures were established by 1D and 2D NMR, and HR‐ESI‐MS spectroscopic analysis and the absolute configuration of 1 was confirmed by ECD calculation. Compounds 1 and 2 were evaluated for the cytotoxic activities, and compounds 1 and 2 showed weak cytotoxic activities towards HepG2 human liver cancer cells, with IC50 values of 97.3 and 79.6 μM, respectively. [ABSTRACT FROM AUTHOR]

A new series of 6‐methoxy‐2‐naphthalene based pyrimidinones were synthesized via one pot‐three component synthetic reaction of aryl aldehydes, 6‐methoxy‐2‐acetonapthone and urea in the presence of nano zinc ferrite catalyst under conventional method. The synthesized compounds were characterized by their spectral techniques including FT‐IR, H1, C13 NMR, LCMS, and analysis of elements. Molecular docking analysis was also performed to identify the protein‐ligand interactions and binding energy of synthesized compounds. Biological studies of all synthesized pyrimidinone compounds have been measured against bacterial and fungal strains by calculating the zone of inhibition. [ABSTRACT FROM AUTHOR]

The emerging Schiff base‐derived metal complexes are the building blocks for biomedical applications. Herein, novel Schiff base N,N′‐[(1Z,2Z)‐1,2‐diphenylethane‐1,2‐diylidene]bis(6‐nitro‐1,3‐thiazol‐2‐amine) and corresponding Cu(II), Ni(II), Mn(II), and Co(II) metal complexes were successfully synthesized and characterized. The characterization of ligand and corresponding metal complexes was carried out by employing elemental analysis, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, mass spectroscopy, Fourier transform infrared spectroscopy (FTIR) analysis, molar conductance, magnetic susceptibility measurements, electronic spectra, electronic paramagnetic resonance (EPR) and density functional theory (DFT) studies. DFT calculations at B3LYP/6‐311+G** level of theory have been executed to examine the equilibrium geometry of the ligand and metal complexes. Furthermore, total energy, highest‐occupied molecular orbital (HOMO) and lowest‐unoccupied molecular orbital (LUMO), and Mulliken atomic charges were reckoned. Tetrahedral geometry was observed in the case of the Ni(II) complex, and octahedral geometries were discerned for Cu(II), Mn(II), and Co(II), complexes. Docking studies were performed against the newly synthesized analogs with the active site of Escherichia coli (PDB ID: 3t88), Staphylococcus aureus (PDB ID: 3q8u), Candida Albicans (PDB ID: 3qlw), and Aspergillus flavus (PDB ID: 4ynt) receptors to recognize the interactions between complexes and identify their probable binding sites. Synthesized analogs were examined for in vitro antimicrobial activity employing both minimum inhibitory concentration and disk diffusion method against the aforementioned pathogens. The result for these pathogens suggested metal compounds evince higher activity in comparison to the free ligand. [ABSTRACT FROM AUTHOR]

The synthesis and properties of titanium phosphonate cluster molecules have been investigated; however, nothing has been done to study not only the catalytic ability of a hydrolyzed cluster but also a behavior of hydrolysis–polycondensation by solvents. The sol–gel reaction of [Ti4(μ3‐O)(OiPr)5(μ‐OiPr)3(O3PPh)3]·thf (Ti4P3Ph) was performed in tetrahydrofuran (THF), toluene, and acetone. The hydrolysis–polycondensation of Ti4P3Ph proceeded in THF and toluene, while Ti4P3Ph in acetone proceeded in two paths (hydrolysis–polycondensation and nonhydrolysis–polycondensation). The hydrolyzed Ti4P3Ph retained its cluster structure, while the calcined Ti4P3Ph at 300°C contained a collapsed cluster structure. The specific surface areas of the hydrolyzed Ti4P3Ph in THF, toluene, and acetone were 154, 302, and 7 m2 g−1, respectively. The photodegradation ability of the hydrolyzed Ti4P3Ph for methylene blue was confirmed by ultraviolet irradiation at 365 nm; however, that of the calcined Ti4P3Ph was not. It was considered that the calcined Ti4P3Ph did not retain its cluster structure. The photocatalytic ability of the hydrolyzed Ti4P3Ph was high in the order of toluene > THF > pristine > acetone. The gels retained cluster structure have higher photocatalytic ability than pristine cluster; however, the gel contained a collapsed cluster structure was found no catalytic ability. [ABSTRACT FROM AUTHOR]

The calculation of the 13C and 15N NMR chemical shifts by a combined molecular mechanics (Pcmodel 9.1/MMFF94) and ab initio (GIAO (B3LYP/DFT, 6‐31 + G(d)) procedure is used to investigate the conformations of a variety of alkyl substituted anilines. The 13C shifts are obtained from the GIAO isotropic shielding (Ciso) with separate references for sp3 and sp2 carbons (δc = δref − Ciso). The 15N shifts are obtained similarly from the GIAO isotropic shielding (Niso) with reference to the 15N chemical shift of aniline. Comparison of the observed and calculated shifts provides information on the molecular conformations. Aniline and the 2,6‐dialkylanilines exist with a rapidly inverting symmetric pyramidal nitrogen atom. The 2‐alkylanilines have similar conformations with the NH2 group tilted away from the 2‐alkyl substituent. The N,N‐dialkylanilines show more varied conformations. N,N‐dimethylaniline has a similar structure to aniline, but N‐ethyl, N‐methylaniline, N,N‐diethylaniline, and N,N‐diisopropylaniline are conformationally mobile with two rapidly interconverting conformers. In contrast, the anilines substituted at C2 and the nitrogen atom exist as one conformer where the steric interaction between the C2 substituent and the N substituent determines the conformation. In 2‐methyl‐N‐methylaniline, the nitrogen atom is pyramidal as usual with the N‐methyl opposite to the 2‐methyl, but in 2‐methyl‐N,N‐dimethyl aniline, the NMe2 group is now almost orthogonal to the phenyl plane. This is also the case with 2‐methyl‐N,N‐diethylaniline and 2,6‐diisopropyl‐N,N‐dimethylaniline. The comparison of the observed and calculated 15N chemical shifts confirms the above findings, in particular the pyramidal conformation of aniline and the above observations with respect to the conformations of the N,N‐dialkylanilines. [ABSTRACT FROM AUTHOR]

The paper shows the structural diversity of cytosine (C)‐rich oligodeoxynucleotides (ODNs) arising from their detail nucleotide sequence and experimental conditions. In slightly acidic solutions, the ODN nonamers with different adenine (A) and cytosine (C) sequences can adopt non‐canonical structures involving protonated bases. A distinct secondary structure formed in (C)‐rich sequences, called i‐motif (iM), consists of hemiprotonated and intercalated cytosine base pairs (C.C+). Folding and unfolding of particular structures in solutions were monitored by 1H NMR and CD spectroscopies and native polyacrylamide gel electrophoresis (PAGE), which are capable to determine their structural characteristics. Effects of sequences and their proclivity to formation of the iM on electrochemical behaviour of the ODN nonamers were studied by electrochemical methods. The LSV signals of A and C obtained from the reductive dissolution of ODN adsorption layers on a hanging mercury drop electrode were processed by elimination voltammetry with linear scan (EVLS), which revealed complex effects of the nonamer properties (namely their primary and secondary structure confirmed in solution) on their adsorption and reduction activity. [ABSTRACT FROM AUTHOR]

A concise and efficient synthesis of a series of amino‐substituted benzimidazole–pyrimidine hybrids has been developed, starting from the readily available N4‐(2‐aminophenyl)‐6‐methoxy‐5‐nitrosopyrimidine‐2,4‐diamine. In each of N5‐benzyl‐6‐methoxy‐4‐(2‐phenyl‐1H‐benzo[d]imidazol‐1‐yl)pyrimidine‐2,5‐diamine, C25H22N6O, (I), 6‐methoxy‐N5‐(4‐methoxybenzyl)‐4‐[2‐(4‐methoxyphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, C27H26N6O3, (III), 6‐methoxy‐N5‐(4‐nitrobenzyl)‐4‐[2‐(4‐nitrophenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, C25H20N8O5, (IV), the molecules are linked into three‐dimensional framework structures, using different combinations of N—H...N, N—H...O, C—H...O, C—H...N and C—H...π hydrogen bonds in each case. Oxidative cleavage of 6‐methoxy‐N5‐(4‐methylbenzyl)‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, (II), with diiodine gave 6‐methoxy‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, which crystallized as a monohydrate, C19H18N6O·H2O, (V), and reaction of (V) with trifluoroacetic acid gave two isomeric products, namely N‐{5‐amino‐6‐methoxy‐6‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidin‐2‐yl}‐2,2,2‐trifluoroacetamide, which crystallized as an ethyl acetate monosolvate, C21H17F3N6O2·C4H8O2, (VI), and N‐{2‐amino‐6‐methoxy‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidin‐5‐yl}‐2,2,2‐trifluoroacetamide, which crystallized as a methanol monosolvate, C21H17F3N6O2·CH4O, (VIIa). For each of (V), (VI) and (VIIa), the supramolecular assembly is two‐dimensional, based on different combinations of O—H...N, N—H...O, N—H...N, C—H...O and C—H...π hydrogen bonds in each case. Comparisons are made with some related structures. [ABSTRACT FROM AUTHOR]

Reaction of 2‐allyl‐N‐benzyl‐4‐fluoroaniline or 2‐allyl‐N‐benzyl‐4‐chloroaniline with 98% sulfuric acid leads to the concurrent formation of halogeno‐substituted 11‐ethyl‐6,11‐dihydrodibenzo[b,e]azepines, (II), and halogeno‐substituted 11‐methyl‐5,6,11,12‐tetrahydrodibenzo[b,f]azocines, (III), in each case in (II):(III) molar ratios of ca 2:1. Further reaction of (II) leads to ethyl 13‐ethyl‐2‐halogeno‐4‐oxo‐8,13‐dihydro‐4H‐benzo[5,6]azepino[3,2,1‐ij]quinoline‐5‐carboxylate, while acetylation of (III) gives the corresponding N‐acetyl derivatives. The dibenzo[b,e]azepine and dibenzo[b,f]azocine ring systems are of importance in forming the core of a variety of bioactive compounds. In ethyl 13‐ethyl‐2‐fluoro‐4‐oxo‐8,13‐dihydro‐4H‐benzo[5,6]azepino[3,2,1‐ij]quinoline‐5‐carboxylate, C22H20FNO3, (IVa), the azepine ring adopts a conformation close to the twist‐boat form, and the molecules are linked into a three‐dimensional framework structure by a combination of C—H...O and C—H...π(arene) hydrogen bonds. The azocine ring in 5‐acetyl‐2‐chloro‐11‐methyl‐5,6,11,12‐tetrahydrobenzo[b,f]azocine, C18H18ClNO, (Vb), adopts the boat–boat conformation and the molecules are again linked by C—H...O and C—H...π(arene) hydrogen bonds, but this time form a sheet structure. [ABSTRACT FROM AUTHOR]

Molecular mechanics calculations plus the application of a refined Karplus equation gave the conformations of 19 pinanes. These range from a Y-shaped geometry in the apopinene and α-pinene series to a pseudo chair conformation in β-pinene, nopinone and verbanone, a flattened chair in pinocarvone and the pinocarveols and a distorted Y shape for iso-verbanone. These structures were then used as input to predict the 1H chemical shifts of these compounds by semi-empirical (1H-NMR spectra (HSPEC)) and ab initio gauge-invariant atomic orbital (GIAO) calculations, the latter at the B3LYP hybrid density functional theory level using 6-31++G** basis set. The two methods gave generally good agreement with the 184 observed shifts with root mean square (RMS) errors 0.07 ppm (HSPEC) and 0.10 ppm (GIAO), but the GIAO calculations gave several significant (>0.25 ppm) errors. One was for the H3 proton in apopinenone and other α, β unsaturated ketones; the others occurred for protons in close proximity to hydroxyl groups. To provide more information, smaller analogues of known geometry and chemical shifts were subject to the same analysis. In cyclopentenone, the Gaussian geometry gave good agreement with the observed shifts, but the MMFF94, MMX and MM3 geometries all gave errors for different protons. These results show clearly that the molecular geometries of the α, β unsaturated ketones are responsible for the errors. The errors for the alcohols were examined using ethanol as model and were shown to be due to the different possible conformations of the OH group. Similar GIAO calculations on substituted methanes gave good agreement for the methyl compounds but poor agreement for di and tri halosubstituted methanes. The aforementioned method of molecular mechanics plus GIAO calculations is shown to be a very useful tool for the investigation of molecular geometries and conformations. However, multihalogen compounds may require different basis sets for accurate calculations. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Three new bleach activators for cotton containing pyridinium (PBBC), nicotinamido (NABBC), and 3-methylpyridinium (3-PBBC) cationic groups were synthesized and characterized by H NMR and HPLC-mass spectrometry. They were then applied to cotton fabric in a bleaching process and evaluated for their performance against the prototype N-[4-(triethylammoniomethyl)benzoyl]butyrolactam chloride (TBBC) at a relatively low bleaching temperature (55 °C) and pH 8.5. Measurement of Commission internationale de l'éclairage (International Commission on Illumination) (CIE) whiteness index (WI) values showed that PBBC (WI = 64), NABBC (WI = 58), and 3-PBBC (WI = 71) impart a significant increase in CIE whiteness compared to a control sample (WI = 40). Among the three new activators, 3-PBBC exhibited the best performance. Its WI was comparable to that of fabric bleached using the prototype bleach activator TBBC. The acute toxicity of TBBC and the new bleach activators was evaluated using the microcrustacean Daphnia similis. The chronic toxicity of TBBC and 3-PBBC was evaluated using the green alga Raphidocelis subcapitata, and mutagenicity was evaluated in the Salmonella/microsome assay using the strain TA100. 3-PBBC was 86 times less toxic to D. similis, 18 times less toxic to R. subcapitata, and 10 times less mutagenic to TA100 in comparison with TBBC. [ABSTRACT FROM AUTHOR]

Solid-state NMR spectroscopy and computational approaches such as Molecular Dynamics (MD) simulations and Density Functional Theory have proven to be very useful and versatile techniques for studying the structure and the dynamics of noncrystalline materials if a direct comparison between experiment and theory is established. In this review, the basic concepts in first-principle modeling of solid-state NMR spectra of oxide glasses are presented. There are three theoretical ingredients in the computational recipe. First, classical or ab initio molecular dynamics simulations are employed to generate the structural models of the glasses of interest. Second, periodic Density Functional Theory calculations coupled with the gauge including projector augmented-wave (GIPAW) algorithm form the basis for the ab initio calculations of NMR parameters (chemical shielding and quadrupolar parameters). Finally, Spin-effective Hamiltonian are employed to simulate the solid-state NMR spectra directly comparable with the experimental counterparts. As an example of this methodology, the investigation of the local and medium range structure of Na-Ca silicate and aluminosilicate glasses that are usually employed as simplified models for basaltic, andesitic and rhyolitic magmas will be reported. We will show how the direct comparison of the theoretical NMR spectra of MD derived structural models with the experimental counterparts allows gaining new insights into the atomistic structure of very complex oxide glasses. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The dynamics and mechanism of proton exchange in phosphonic acid-functionalized polymers were studied using poly(vinyl-phosphonic acid) (PVPA) as a model system along with quantum chemical calculations and Born-Oppenheimer molecular dynamics (BOMD) simulations at the B3LYP/TZVP level as model calculations. This theoretical study began with searching for the smallest, most active polymer segments and their intermediate conformations which could be involved in the local proton-exchange process. The B3LYP/TZVP results confirmed that a low local dielectric environment and excess proton conditions are required to generate the intermediate conformations, and the shapes of the potential energy curves of the proton exchange between the two phosphonic acid functional groups are sensitive to the local conformational changes. In contrast, a high local dielectric environment increases the energy barriers, thereby preventing the proton from returning to the original functional group. Based on the static results, a mechanism for the proton exchange between the two functional groups involving fluctuations in the local dielectric environment and a local conformational change was proposed. The BOMD results confirmed the proposed mechanism by showing that the activation energies for the proton exchange in the hydrogen bond between two immobilized phosphonic acid moieties, obtained from the exponential relaxation behaviors of the envelopes of the velocity autocorrelation functions and the 1H Nuclear Magnetic Resonance (NMR) line-shape analyses, are too low to be the rate-determining process. Instead, coupled librational motion in the backbone which leads to the interconversion between the two intermediate conformations possesses higher activation energy, and therefore represents one of the most important rate-determining processes. These findings suggested that the rate of the proton exchange in the model phosphonic acid-functionalized polymer is determined by the polymer mobility which, in this case, is the large-amplitude librational motion of the vinyl backbone. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

(1 R,2 R,3 S,4 R,7 R)-7-Isopropyl-6-methylbicyclo[2.2.2]oct-5-ene-2,3-dicarboxylic acid anhydride (tetrahydro-4,7-ethanoisobenzofuran-1,3-dione derivative) adduct 2 was prepared via the isomerization of α-pinene and β-pinene in turpentine followed by the Diels-Alder cycloaddition with maleic anhydride in the presence of phosphoric acid/iodine catalysis. The molecular structure of adduct 2 was characterized by IR, 1H NMR, 13C NMR, 1H-1H COSY, DEPT, HSQC, HMBC, 2D NOESY and MS spectra. The single crystal X-ray crystallographic analysis of adduct 2 was performed, and the X-ray powder diffractive spectrum of the sample adduct 2 is consistent with the diffractive spectrum calculated from the single crystal data. Therefore the structure and stereochemistry of adduct 2 was established based on extensive spectral data and single crystal X-ray analysis. [ABSTRACT FROM AUTHOR]

In a recent 17O NMR spectra of liquid sulfur trioxide, several unexpected peaks appeared with the temperature-dependent integrated peak ratio. In order to interpret NMR spectra and assign peaks to possible molecular structures, the theoretical quantum mechanical density functional theory and Møller-Plesset second-order perturbation theory calculations were performed. It is suggested that in the liquid sulfur trioxide, apart from monomeric SO3, a significant amount of (SO3)3 cyclic trimers should appear. No theoretical data support hypothesis on (SO3)2 dimers formation. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this study 2-(2′-furyl)-4,5-1H-dihydroimidazole (1) was prepared and then characterized by infrared, Raman, and multidimensional nuclear magnetic resonance (NMR) spectroscopies. The crystal and molecular structures of 1 were determined by X-ray diffraction methods. The density functional theory (DFT) and second-order Møller–Plesset theory (MP2) with Pople's basis set show that there are two conformers for the title molecule that have been theoretically determined in the gas phase, and that only one of them, conformer I, is present in the solid phase. NMR spectra observed for 1 were successfully compared with the calculated chemical shifts at the B3LYP/6-311++G** level theorized for this conformer. The harmonic vibrational frequencies for the optimized geometry of the latter conformer were calculated at the B3LYP/6-311++G** level in the approximation of the isolated molecule. For a complete assignment of the IR and Raman spectra in the solid phase of 1, DFT calculations were combined with Pulaýs scaled quantum mechanics force field (SQMFF) methodology to fit the theoretical frequency values to the experimental ones. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The influence of the position of nitro group toward the carboxylic group on the vibration structure of the molecule was estimated. Optimized geometrical structures were calculated (HF, B3PW91, B3LYP). Experimental and theoretical FT-IR, FT-Raman, and nuclear magnetic resonance (NMR) spectra of the title compounds were recorded and analyzed. The most important vibrational bands of nitro and carboxyl groups and the benzene ring were assigned. Wavenumbers and intensities for the three acids studied were compared and discussed. Data of chemical shifts in 1H and 13C NMR spectra of 2-, 3-, and 4-nitrobenzoic acids were analyzed in comparison with benzoic acid molecule. The calculated parameters are compared with experimental characteristics of these molecules. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [ABSTRACT FROM AUTHOR]