Raman spectrum of single-walled boron nitride nanotube

Using the spectral moments method, the calculations of the Raman spectra of single-walled boron nitride nanotubes (SW-BNNTs) were performed in the framework of the force constants model. Spectra were computed for chiral and achiral nanotubes for different diameters and lengths. The Raman scattering intensities were determined using the bond-polarizability model and a good agreement with group theory analysis was found. We show that the modes in the low frequency region are very sensitive to the nanotube diameter variation, whereas the ones associated to the tangential region are chirality dependent. The number of Raman active modes, their frequencies, and intensities depend on the length of the nanotube.     

Etude Des Proprietes Physico-Chimiques du Cyclotriphosphate Mixte de Nickel et D'argent Hexahydrate,NiAg 4 (P 3 O 9 ) 2 ·6H 2 O

We have studied the dehydration and the calcination under atmospheric pressure of cyclotriphosphate hexahydrate of nickel and silver, NiAg 4 (P 3 O 9 ) 2 ·;6H 2 O, between 25 and 600°;C by infrared spectrometry, x-ray diffraction, thermal analyses TGA, and DTA. This study led us to the identification and the crystallographic characterization of a new phase, NiAg 4 (PO 3 ) 6 , obtained between 250 and 350°;C. NiAg 4 (PO 3 ) 6 crystallizes in the triclinic system, P m 1 , with the following unit cell parameters a = 6.100(2)Å, b = 6.783(1)Å, c = 10.764(2)Å, f = 78.66(3)°;, g = 96.85(3)°;, n = 113.36(2)°;, Z = 1, V = 401Å 3 , M(20) = 133, and F(30) = 88 (0.0017; 197). The calcination of NiAg 4 (PO 3 ) 6 , between 400 and 500°;C, leads to a mixture of long-chain polyphosphates NiAg(PO 3 ) 3 and AgPO 3 . The kinetic characteristics of the dehydration of NiAg 4 (P 3 O 9 ) 2 ·;6H 2 O were determined and discussed. The vibrational spectrum of the title compound, NiAg 4 (P 3 O 9 ) 2 ·;6H 2 O, was interpreted in the domain of the stretching vibrations of the P 3 O 9 rings, on the basis of its crystalline structure and in the light of the calculation of the normal IR frequencies of the P 3 O 9 ring with the idealized D 3h symmetry. L'étude de la déshydratation et de la calcination, sous pression atmosphérique, du cyclotriphosphate de nickel tétra-argent, NiAg 4 (P 3 O 9 ) 2 ·;6H 2 O, a été effectuée, entre 25 et 600°;C, par spectrométrie IR, diffraction des rayons x, ATG, et ATD. Elle a permis l'identification et la caractérisation cristallographique d'une nouvelle phase, NiAg 4 (PO 3 ) 6 , obtenue entre 250 et 350°;C. NiAg 4 (PO 3 ) 6 cristallise dans le système triclinique, de groupe d'espace P m 1 avec Z = 1. Les paramètres de maille sont: a = 6.100(2)Å, b = 6.783(1)Å, c = 10.764(2)Å, f = 78.66(3)°;, g = 96.85(3)°;, n = 113.36(2)°;, V = 401Å 3 et les facteurs de mérite sont: M(20) = 133, et F(30) = 88 (0.0017; 197). La calcination du composé, entre 400 et 500°;C, conduit au mélange de polyphosphates à chaînes infinies NiAg(PO 3 ) 3 et AgPO 3 . Les caractéristiques cinétiques de la déshydratation de NiAg 4 (P 3 O 9 ) 2 ·;6H 2 O ont été déterminées et discutées. Le spectre IR du sel étudié a été interprété, dans le domaine des vibrations de valence des cycles, sur la base de la structure cristalline connue de son isotype NiNa 4 (P 3 O 9 ) 2 ·;6H 2 O et de nos résultats de calcul des fréquences IR fondamentales du cycle P 3 O 9 3 m de symétrie idéale D 3h .     

(1S,3R,8S,9S,10R)‐2,2‐Dichloro‐9,10‐epoxy‐3,7,7,10‐tetramethyltricyclo[6.4.0.01,3]dodecane and (1S,3R,8S,10R)‐2,2‐dichloro‐3,7,7,10‐tetramethyltricyclo[6.4.0.01,3]dodecan‐9‐one

The stereochemistries of the title compounds, both C₁₆H₂₄Cl₂O, have been established by X‐ray diffraction. In both structures, the seven‐membered ring adopts the same conformation, whereas the six‐membered ring shows an envelope conformation in the epoxy­do­decane structure and a boat conformation in the dodecan‐9‐one structure.     

Etude des Propriétés Physico-Chimiques de CuK 4 (P 3 O 9 ) 2 .4H 2 O

The dehydration of CuK 4 (P 3 O 9 ) 2 .4H 2 O was investigated, between 25 and 700°;C, by TG-DTA, x-ray diffraction, and IR. It leads, at 500°;C, to a mixture of long chain polyphosphates KPO 3 and CuK 2 (PO 3 ) 4 which remains stable until its melting point. The kinetic characteristics of the dehydration of CuK 4 (P 3 O 9 ) 2 .4H 2 O were determined and discussed. The vibrational spectrum of the title compound, CuK 4 (P 3 O 9 ) 2 .4H 2 O, was interpreted in the domain of the stretching vibrations of the P 3 O 9 rings on the basis of its crystalline structure and in the light of the calculation of the normal IR frequencies of the P 3 O 9 ring with the idealized D 3h symmetry.     

3D QSAR Modeling and Molecular Docking Studies on a Series of Triazole Analogues as Antibacterial Agents

The 3D QSAR analysis using the comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques is performed on novel nalidixic acid based 1,2,4-triazole derivatives suggested earlier as antibacterial agents. The CoMFA and CoMSIA models employed for a training set of 28 compounds gives reliable values of Q² (0.53 and 0.52, respectively) and R² (0.79 and 0.85, respectively). The contour maps produced by the CoMFA and CoMSIA models are used to determine a three-dimensional quantitative structure-activity relationship. Based on the 3D QSAR contours new molecules with high predicted activities are designed. In addition, surflex-docking is performed to confirm the stability of predicted molecules in the receptor.     

Furanone derivatives as new inhibitors of CDC7 kinase: development of structure activity relationship model using 3D QSAR,molecular docking,and in silico ADMET

Cell division cycle 7 (CDC7) is a serine/threonine kinase, which plays a vital role in the replication initiation of DNA synthesis. Overexpression of the CDC7 in various tumor growths and in cell proliferation makes it a promising target for treatment of cancers. To investigate the binding between the CDC7 and furanone inhibitors, and in order to design highly potent inhibitors, a three-dimensional quantitative structure activity relationship (3D-QSAR) with molecular docking was performed. The optimum CoMSIA model showed significant statistical quality on all validation methods with a determination coefficient (R²?=?0.945), bootstrapping R² mean (BS-R²?=?0.960), and leave-one-out cross-validation (Q²) coefficient of 0.545. The predictability of this model was evaluated by external validation using a test set of nine compounds with a predicted determination coefficient R²_test of 0.96, besides the mean absolute error (MAE) of the test set was 0.258 log units. The extracted contour maps were used to identify the important regions, where the modification was necessary to design a new molecule with improved activity. Furthermore, a good consistency between the molecular docking and contour maps strongly demonstrates that the molecular modeling is reliable. Based on those obtained results, we designed several new potent CDC7 inhibitors, and their inhibitory activities were validated by the molecular models. Additionally, those newly designed inhibitors showed promising results in the preliminary in silico ADMET evaluations.     

Investigation of indirubin derivatives: a combination of 3D-QSAR,molecular docking,and ADMET towards the design of new DRAK2 inhibitors

Kinase-related apoptosis-inducing kinase 2 (DRAK2) is a serine/threonine kinase and belongs to the death-associated protein kinase DPAK family, which is responsible for induction of apoptosis in many cell types. Thus, DRAK2 is regarded as a promising target for treatment of autoimmune diseases. To investigate the binding between DRAK2 and indirubin inhibitors and design potent inhibitors, a three-dimensional quantitative structure-activity relationship (3D-QSAR) and molecular docking were performed. Comparative Molecular Similarity Indices Analysis (CoMSIA) was developed using 33 molecules having pIC₅₀ ranging from 8.523 to 5.000 (IC₅₀ in nM). The best CoMSIA model gave a significant coefficient of determination (R²?=?0.93), as well as a (leave-one-out cross-validation coefficient Q² of 0.81. The predictive ability of this model was evaluated by external validation using a test set of eight compounds and yielded a predicted coefficient of determination R²_test of 0.94. The contour maps could provide structural features to improve inhibitory activity. Good consistency between contour maps and molecular docking strongly suggests that the molecular modeling is reliable. Based on these satisfactory results, we designed several new DRAK2 inhibitors and their inhibitory activities were predicted using different models, which are developed on different training and test sets. Additionally, these newly designed inhibitors showed promising results in the preliminary in silico ADMET evaluations compared to the best inhibitor from the studied dataset. This study could be useful in lead identification and optimization for early drug discovery of DRAK2 inhibitors.     

Chemical Preparation,Crystallographic Data,Thermal Behavior,and IR Studies of MnNa 4 (P 3 O 9 ) 2 ·4H 2 O

Chemical preparation, crystallographic data, thermal behavior, and IR studies are given for two cyclotriphosphates MnNa 4 (P 3 O 9 ) 2 ;4H 2 O and its anhydrous form MnNa 4 (P O 9 ) 2 . MnNa 4 (P 3 O 9 ) 2 ;4H 2 O, isotypic of CuK 4 (P 3 O 9 ) 2 ;4H 2 O, is monoclinic P2 1 /a with the following unit-cell dimensions: a = 8.536(2) Å, b = 14.309(3) Å, c = 8.508(2) Å, g = 96.452(2); and Z = 2. MnNa 4 (P 3 O 9 ) 2 , isotypic of CaNa 4 (P 3 O 9 ) 2 , is monoclinic C2/c with the following unit-cell dimensions: a = 13.198(2) Å, b = 8.241(1) Å, c = 14.228(2) Å, g = 95.045(1); and Z = 4. The thermal behavior has been investigated and interpreted by comparison with IR absorption spectrometry and x-ray diffraction experiments.     

Complexation du 2‐[(5‐méthyl­pyrazolyl)méthyle]benzimidazole par les chlorures de cuivre et de cadmium

The structures of dichloro{2‐[(5‐methyl‐1H‐pyrazol‐3‐yl‐κN²)methyl]‐1H‐1,3‐benzimidazole‐κN³}copper(II), [CuCl₂(C₁₂H₁₂N₄)], and di‐μ‐chloro‐bis(chloro{2‐[(5‐methyl‐1H‐pyrazol‐3‐yl‐κN²)methyl]‐1H‐1,3‐benzimidazole‐κN³}­cadmium(II)), [Cd₂Cl₄(C₁₂H₁₂N₄)₂], show that these compounds have the structural formula [ML(Cl)₂]_n, where L is 2‐[(5‐methylpyra­zolyl)methyl]benzimidazole. When M is copper, the complex is a monomer (n = 1), with a tetrahedral coordination for the Cu atom. When M is cadmium (n = 2), the complex lies about an inversion centre giving rise to a centrosymmetric dimer in which the Cd atoms are bridged by two chloride ions and are pentacoordinated.