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831.
William H. Watson Ram P. Kashyap Mariusz Krawiec Duoli Sun Thomas F. Carlson Alan P. Marchand Yanjun Wang 《Journal of chemical crystallography》1994,24(4):259-266
2,8,10,11-Tetrachloro-12-oxahexacyclo[7,2.1.02.8.03.7.04.11.06.10]dodeca-1,9-diol is a strained cage molecule containing six five-membered rings and a four-membered ring. Twenty-five of the internal angles are less than 105° with 6 ranging from 89.5(3) to 97.4(3)°. The base promoted reaction of 3,6-dipyridyl-1,2,4,5-tetrazine with tetracyclo[6.3.0.04.11.05.9]undecane-3,6-dione yields the monoketone 6,7-[3,6-di(2-pyridyl)-4,5-pyridizino]tetracyclo[6.3.0.04.11.05.9]-undecan-2-one. This compound crystallizes in the centrosymmetric space group P21/n with enantiomers related by a center of symmetry. In the crystal investigated the molecules are disordered with each site containing about 80% of one isomer and 20% of the enantiomer. When the ketone is hydrogenated and the product isolated, two different crystals were found to have a ratio of alcohol to ketone of .71/.29 and .75/.25 or about 3/1. The alcohol and ketone occupy the same sites, but with opposite stereochemistries. 相似文献
832.
Manuel Soriano-García Simón Hernández-Ortega Eugene Bratoeff Norma Valencia Elena Ramírez Gregoria Flores 《Journal of chemical crystallography》1998,28(6):487-491
The title compound is C29H34O4, tetragonal, P43, a = b = 10.310(1), c = 23.871(2)Å. The A, B, C, and D rings adopt envelope, half-chair, chair, and distorted chair conformations, respectively. The phenyl ring is planar. The methyl substituents at the A/B, C/D, and at C(17) are axial; and the –OCOCH3 group at C(17) and phenyl ring at C(16) are equatorial. The molecules in the crystal are held together by van der Waals forces and several C–H···O hydrogen bond interactions. 相似文献
833.
Bhargav Shreevatsa Chandan Dharmashekara Vikas Halasumane Swamy Meghana V. Gowda Raghu Ram Achar Vivek Hamse Kameshwar Rajesh Kumar Thimmulappa Asad Syed Abdallah M. Elgorban Salim S. Al-Rejaie Joaquín Ortega-Castro Juan Frau Norma Flores-Holguín Chandan Shivamallu Shiva Prasad Kollur Daniel Glossman-Mitnik 《Molecules (Basel, Switzerland)》2021,26(22)
NAD(P)H:quinone acceptor oxidoreductase-1 (NQO1) is a ubiquitous flavin adenine dinucleotide-dependent flavoprotein that promotes obligatory two-electron reductions of quinones, quinonimines, nitroaromatics, and azo dyes. NQO1 is a multifunctional antioxidant enzyme whose expression and deletion are linked to reduced and increased oxidative stress susceptibilities. NQO1 acts as both a tumor suppressor and tumor promoter; thus, the inhibition of NQO1 results in less tumor burden. In addition, the high expression of NQO1 is associated with a shorter survival time of cancer patients. Inhibiting NQO1 also enables certain anticancer agents to evade the detoxification process. In this study, a series of phytobioactives were screened based on their chemical classes such as coumarins, flavonoids, and triterpenoids for their action on NQO1. The in silico evaluations were conducted using PyRx virtual screening tools, where the flavone compound, Orientin showed a better binding affinity score of −8.18 when compared with standard inhibitor Dicumarol with favorable ADME properties. An MD simulation study found that the Orientin binding to NQO1 away from the substrate-binding site induces a potential conformational change in the substrate-binding site, thereby inhibiting substrate accessibility towards the FAD-binding domain. Furthermore, with this computational approach we are offering a scope for validation of the new therapeutic components for their in vitro and in vivo efficacy against NQO1. 相似文献
834.
X-ray powder diffraction data on the molecular semiconductors based on the 1:1 charge-transfer complexes of the electron donors, viz. phenothiazine (PTZ), 2-chlorophenothiazine (CPZ), 2-acetyl phenothiazine (APZ) and 2-(trifluoromethyl)-phenothiazine (TPZ) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) have been reported in this paper. The indexing has been done by Ito's method. All the complexes have been found to have orthorhombic crystal structures. The lattice parameters for the individual complexes are as follows: (i) PTZ-DDQ: a = 6.020 Å, b = 9.775 Å, c = 24.280 Å; (ii) CPZ-DDQ: a = 5.830 Å, b = 8.070 Å, c = 20.280 Å; (iii) APZ-DDQ: a = 5.055 Å, b = 7.955 Å, c = 19.520 Å; (iv) TPZ-DDQ: a = 5.130 Å, b = 8.195 Å, c = 19.850 Å. 相似文献
835.
836.
A physical chemistry experiment is described that involves the determination of some spectroscopic parameters of carbon dioxide, a molecule that obeys Bose-Einstein statistics. The main advantage of this experiment is that the spectra are easily recorded, not requiring a gas cell, because the sensitivity and resolution of conventional FTIR spectrometers is good enough to record spectra with a high signal-to-noise ratio and good resolution of the fine rotational structure. From the rotational lines of the antisymmetric stretching band, the moments of inertia and the bond lengths of CO2 in the fundamental and the first-excited state can be accurately obtained. The particular case that carbon dioxide represents helps students understand the restrictions that symmetry and statistics impose on some molecules and the consequences that they have on the absorption of radiation. 相似文献
837.
M Cabeza A Quiroz E Bratoeff M E Murillo E Ramírez G Flores 《Chemical & pharmaceutical bulletin》1999,47(9):1232-1236
The pharmacological activity of eight pregnane derivatives 17-alpha acetoxyprogesterone 9, 17-alpha acetoxy-4, 5-epoxypregnan-3, 20-dione 10, 17-alpha acetoxy-4-chloro-4-pregnene-3, 20-dione 11, 17-alpha acetoxy-4-bromo-4-pregnene-3, 20-dione 12, 17-alpha hydroxy-4-bromo-4-pregnene-3, 20-dione 13, 4-chloro-17-alpha hydroxy-4-pregnene-3, 20-dione 14, 17-alpha benzoyloxy-4-bromo-4-pregnene-3, 20-dione 15 and 17-alpha benzoyloxy-4-chloro-4-pregnene-3, 20-dione 16 was determined. These compounds were evaluated as antiandrogens on gonadectomized hamster seminal vesicles. The pharmacological data in this study indicate that compounds 15 and 16 having a C-17 benzoyloxy moiety showed the highest antiandrogenic activity as measured by the reduction of the weight of the seminal vesicles, followed by the steroids 11 and 12 (17-alpha acetoxy group). The free alcohols 13 and 14 exhibited a lower antiandrogenic activity. Apparently, the ester moiety at C-17 is a necessary requirement for the presence of high antiandrogenic activity. Shows the inhibitory effect on the conversion of testosterone (T) to DHT, of the above described steroids as measured by the amount of produced DHT 2 expressed as pmoles of DHT/g of protein/h. Steroids 11, 12 and 16 showed a much higher inhibitory activity on the conversion of testosterone (T) to dihydrotestosterone (DHT) than presently used finasteride 3. 相似文献
838.
Cover Picture: Synthesis,Characterization, and Fluorescence Chemosensor Properties of a cis‐Dioxomolybdenum(VI) Complex Containing Multidentate Hydrazone Ligands (Z. Anorg. Allg. Chem. 13/2017) 下载免费PDF全文
839.
Angela Luis Matos Tej B. Limbu Ivan Castillo Muhammad Shehzad Sultan Balram Tripathi Ram S. Katiyar Brad R. Weiner Gerardo Morell 《Macromolecular Symposia》2024,413(1):2300040
Large area single and bilayer graphene are grown on Pt/Ti/SiO2 substrates by hot filament chemical vapor deposition (HFCVD) with and without the assistance of Cu foil. The quality and number of graphene layers deposited on the substrate are assessed by Raman Spectroscopy. Atomic Force Microscopy (AFM) is used for assessing the surface topography of the graphene films grown on the Pt/Ti/SiO2 substrates. The microstructure and elemental analyses are performed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The results show that bilayer graphene growth is facilitated by a copper foil placed nearby Pt/Ti/SiO2 substrate and by a high filament temperature in the HFCVD reactor. Monolayer graphene grows only when no copper foil is placed near the Pt/Ti/SiO2 substrate at a low filament temperature. The approach paves a novel pathway towards the layer-controlled growth of graphene on Pt/Ti/SiO2 substrates by HFCVD for frontier applications. 相似文献
840.
Jrg Küther Ram Seshadri Wolfgang Tremel 《Angewandte Chemie (International ed. in English)》1998,37(21):3044-3047
Gold colloids modified with p-sulfanylphenol self-assembled monolayers provide novel nanoscopic seeds for the nucleation of calcium and strontium carbonate from aqueous solution. The morphologies of the crystalline precipitates are very different from what can normally be obtained through templated crystallization on flat surfaces. 相似文献