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901.
Banafsheh Vahdani Alviri Mehrdad Pourayoubi Abdul Ajees Abdul Salam Marek Ne
as Arie van der Lee Akshara Chithran Krishnan Damodaran 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(1):104-116
The crystal structures of diphenyl (cycloheptylamido)phosphate, C19H24NO3P or (C6H5O)2P(O)(NHC7H13), ( I ), and diphenyl (dibenzylamido)phosphate, C26H24NO3P or (C6H5O)2P(O)[N(CH2C6H5)2], ( II ), are reported. The NHC7H13 group in ( I ) provides two significant hydrogen‐donor sites in N—H…O and C—H…O hydrogen bonds, needed for a one‐dimensional hydrogen‐bond pattern along [100] in the crystal, while ( II ), with a (C6H5CH2)2N moiety, lacks these hydrogen bonds, but its three‐dimensional supramolecular structure is mediated by C—H…π interactions. The conformational behaviour of the phenyl rings in ( I ), ( II ) and analogous structures from the Cambridge Structural Database (CSD) were studied in terms of flexibility, volume of the other group attached to phosphorus and packing forces. From this study, synclinal (±sc), anticlinal (±ac) and antiperiplanar (±ap) conformations were found to occur. In the structure of ( II ), there is an intramolecular Cortho—H…O interaction that imposes a +sc conformation for the phenyl ring involved. For the structures from the CSD, the +sc and ±ap conformations appear to be mainly imposed by similar Cortho—H…O intramolecular interactions. The large contribution of the C…H/H…C contacts (32.3%) in the two‐dimensional fingerprint plots of ( II ) is a result of the C—H…π interactions. The differential scanning calorimetry (DSC) analyses exhibit peak temperatures (Tm) at 109 and 81 °C for ( I ) and ( II ), respectively, which agree with the strengths of the intermolecular contacts and the melting points. 相似文献
902.
Atif Muhammad Karim Ramzan Abdul Khaliq Zubair Bongiovanni Roberta 《Russian Journal of Applied Chemistry》2020,93(2):305-312
Russian Journal of Applied Chemistry - Surface chemistry of carbon black (CB) plays a major role towards its dispersion in liquid media. In this study a simple approach of surface modification has... 相似文献
903.
Akbar Ali Muhammad Khalid Saba Abid Javed Iqbal Muhammad Nawaz Tahir Abdul Rauf Raza Julio Zukerman-Schpector Marcio Weber Paixão 《应用有机金属化学》2020,34(3):e5399
The pyridine-based halogenated hydrazone derivatives (E)-N′-benzylidene-2-[(6″-chloroazin-2″-yl)oxy]acetohydrazide ( 6a ), (E)-N′-(3′-chlorobenzylidene)-2-[(6″-chloroazin-2″-yl)oxy]acetohydrazide ( 6b ) and (E)-N′-(3′-bromobenzylidene)-2-[(6″-chloroazin-2″-yl)oxy]acetohydrazide ( 6c ) have been obtained using 6-chloro-2-hydroxypyridine. The structure of the products ( 6a – c ) has been verified using X-ray crystallography and spectroscopic approaches. A single-crystal X-ray diffraction (SC-XRD) investigation showed that the structures are stabilized by intermolecular attractive forces. Additionally, density functional theory (DFT) has been adopted to explore the structural properties, vibrational spectra, noncovalent interactions and frontier molecular orbitals using the B3LYP/6-311 + G(d,p) level. The nonlinear optical properties of the title compounds were calculated using the CAM-B3LYP/6-311 + G(d,p) level. Frequency analysis confirmed the stability of the molecules, and an excellent correlation was observed between the DFT- and SC-XRD-based structural parameters. The SC-XRD analysis confirmed that the dimers of 6a , 6b and 6c are linked by hydrogen-bonding interactions. Natural bond orbital (NBO) analysis also reconfirmed the strength of intermolecular hydrogen-bonding and hyperconjugative interactions. NBO investigation was also utilized to analyze the atomic charges. Moreover, Fourier transform infrared and natural population analyses endorsed that there are significant N&bond;H⋅⋅⋅O&dbond;C hydrogen-bonding linkages in dimeric structures of the compounds. The hydrogen-bonding network and different sorts of hyperconjugative interactions are the main reasons for the stability of the products in the solid state. The highest occupied and lowest unoccupied molecular orbital energies and first-order nonlinear optical properties of these molecules are reported. The quantum chemical parameters were derived using frontier molecular orbital energies. 相似文献
904.
This study presents an efficient synthesis of 3-[6-(substituted-phenyl)-[1,2,4]triazolo[3,4-b][1,3,4] thiadiazol-3-yl]-1H-indazole via dehydrative condensation with cyclization of 4-amino-5-(1H-indazol-3-yl)-4H-[1,2,4]triazole-3-thiol and fluorinated or nonfluorinated carboxylic acids in presence of phosphorous oxychloride. The multistep reaction pathway proceeds through different compounds. Present synthesis has the advantages of easily accessible starting materials, convenient synthesis, simple reaction condition, wider substrate scope, and higher yield (75% to 90% isolated). 相似文献
905.
Shaista PARVEEN Saima KALSOOM Rifhat BIBI Ambreen ASGHAR Abdul HAMEED Waqar AHMED Abbas HASSAN 《Turkish Journal of Chemistry》2020,44(6):1610
The current investigation presents the synthesis, computational molecular-docking and biological activity studies of arylated thiazole coumarins. Aryl substituted thiazolyl coumarin derivatives were synthesized via Suzuki cross-coupling reaction. A detailed reaction condition optimization revealed that the Pd-PEPPSI-IPent precatalyst in only 2 mol% loading resulted in the desired product with high yield. The aim of this study was to examine the antimicrobial behavior of thiazole coumarin derivatives through in vitro and in silico studies. All the compounds showed activity against both antibacterial strains, Staphylococcus aureus and Escherichia coli, except 5d . Similarly, the compounds 5a , 5b , and 5d were found to be active against Trichoderma harzianum. The compound 5d of this series was found to have a higher activity with MIC 125 mg/ml against Trichoderma harzianum. Molecular studies showed the high activities of these compounds are due to the presence of strong H-bonding and π-π interaction with their respective targets. A good correlation was observed between computational and in vitro studies. 相似文献
906.
Optical and Photoacoustic Properties of Laser-Ablated Silver Nanoparticles in a Carbon Dots Solution
Amir Reza Sadrolhosseini Ganesan Krishnan Suhaidi Shafie Suraya Abdul Rashid Sulaiman Wadi Harun 《Molecules (Basel, Switzerland)》2020,25(24)
This study used the carbon dots solution for the laser ablation technique to fabricate silver nanoparticles. The ablation time range was from 5 min to 20 min. Analytical methods, including Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy, transmission electron microscopy, and Raman spectroscopy were used to categorize the prepared samples. The UV-visible and z-scan techniques provided optical parameters such as linear and nonlinear refractive indices in the range of 1.56759 to 1.81288 and 7.3769 × 10−10 cm2 W−1 to 9.5269 × 10−10 cm2 W−1 and the nonlinear susceptibility was measured in the range of 5.46 × 10−8 to 6.97 × 10−8 esu. The thermal effusivity of prepared samples, which were measured using the photoacoustic technique, were in the range of 0.0941 W s1/2 cm−2 K−1 to 0.8491 W s1/2 cm−2 K−1. The interaction of the prepared sample with fluoride was investigated using a Raman spectrometer. Consequently, the intensity of the Raman signal decreased with the increasing concentration of fluoride, and the detection limit is about 0.1 ppm. 相似文献
907.
Nur Fazrin Husna Abdul Aziz Sahar Abbasiliasi Zhang Jin Ng Mazni Abu Zarin Siti Nurbaya Oslan Joo Shun Tan Arbakariya Bin Ariff 《Molecules (Basel, Switzerland)》2020,25(22)
Lactobacillus bulgaricus is a LAB strain which is capable of producing bacteriocin substances to inhibit Staphylococcus aureus. The aim of this study was to purify a bacteriocin-like inhibitory substance (BLIS) produced by L. bulgaricus FTDC 1211 using an aqueous impregnated resins system consisting of polyethylene-glycol (PEG) impregnated on Amberlite XAD4. Important parameters influencing on purification of BLIS, such as the molecular weight and concentration of PEG, the concentration and pH of sodium citrate and the concentration of sodium chloride, were optimized using a response surface methodology. Under optimum conditions of 11% (w/w) of PEG 4000 impregnated Amberlite XAD4 resins and 2% (w/w) of sodium citrate at pH 6, the maximum purification factor (3.26) and recovery yield (82.69% ± 0.06) were obtained. These results demonstrate that AIRS could be used as an alternate purification system in the primary recovery step. 相似文献
908.
Cramer CJ Gour JR Kinal A Włoch M Piecuch P Shahi AR Gagliardi L 《The journal of physical chemistry. A》2008,112(16):3754-3767
The relative energies of side-on versus end-on binding of molecular oxygen to a supported Cu(I) species, and the singlet versus triplet nature of the ground electronic state, are sensitive to the nature of the supporting ligands and, in particular, depend upon their geometric arrangement relative to the O2 binding site. Highly correlated ab initio and density functional theory electronic structure calculations demonstrate that optimal overlap (and oxidative charge transfer) occurs for the side-on geometry, and this is promoted by ligands that raise the energy, thereby enhancing resonance, of the filled Cu dxz orbital that hybridizes with the in-plane pi* orbital of O2. Conversely, ligands that raise the energy of the filled Cu dz2 orbital foster a preference for end-on binding as this is the only mode that permits good overlap with the in-plane O2 pi*. Because the overlap of Cu dz2 with O2 pi* is reduced as compared to the overlap of Cu dxz with the same O2 orbital, the resonance is also reduced, leading to generally more stable triplet states relative to singlets in the end-on geometry as compared to the side-on geometry, where singlet ground states become more easily accessible once ligands are stronger donors. Biradical Cu(II)-O2 superoxide character in the electronic structure of the supported complexes leads to significant challenges for accurate quantum chemical calculations that are best addressed by exploiting the spin-purified M06L local density functional, single-reference completely renormalized coupled-cluster theory, or multireference second-order perturbation theory, all of which provide predictions that are qualitatively and quantitatively consistent with one another. 相似文献
909.
Hussain M Zahra DN Hussain SM Ahmed E Ahmad I Malik A Ahmed Z 《Magnetic resonance in chemistry : MRC》2008,46(3):274-277
Two new steroids provisionally named as pakisteroid-A (1) and pakisteroid-B (2) have been isolated in crystalline form from Abutilon pakistanicum. Their structures have been assigned as 3-O-beta-D-glucopyranosyl-stigmasta-5,11(12)-diene (1) and 24beta-ethylcholesta-5, 9(11), 22E-trien-3beta-benzoate (2), respectively through extensive NMR studies. 相似文献
910.
Ahmad Z Mehmood S Fatima I Malik A Ifzal R Afza N Iqbal L Latif M Nizami TA 《Magnetic resonance in chemistry : MRC》2008,46(1):94-98
Salsolins A (1) and B (2), the new triterpenes, have been isolated from the chloroform soluble fraction of Salsola baryosma along with 2alpha,3beta,23,24-tetrahydroxyurs-12-en-28-oic acid (3) reported for the first time from this species. Their structures have been assigned from 1H and 13C NMR spectra, DEPT and by 2D COSY, NOESY, HMQC and HMBC experiments. The compounds 1-3 showed significant antioxidant activity. 相似文献