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111.
Jayaraman Selvakumar Meredith H. Miles David A. Grossie Kuppuswamy Arumugam 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(4):462-468
Diffraction‐quality single crystals of two gold(I) complexes, namely bis(1,3‐dimesityl‐4,5‐naphthoquinoimidazol‐2‐ylidene)gold(I) chloride benzene monosolvate, [Au(C29H26N2O2)2]Cl·C6H6 or [(NQMes)2Au]Cl·C6H6, 2 , and bis(1,3‐dimesityl‐4,5‐naphthoquinoimidazol‐2‐ylidene)gold(I) dichloridoaurate(I) dichloromethane disolvate, [Au(C29H26N2O2)2][AuCl2]·2CH2Cl2 or [(NQMes)2Au][AuCl2]·2CH2Cl2, 4 , were isolated and studied with the aid of single‐crystal X‐ray diffraction analysis. Compound 2 crystallizes in a monoclinic space group C2/c with eight molecules in the unit cell, while compound 4 crystallizes in the triclinic space group P with two molecules in the unit cell. The crystal lattice of compound 2 reveals C—H…Cl? interactions that are present throughout the entire structure representing head‐to‐tail contacts between the aromatic (C—H) hydrogens of naphthoquinone and Cl? counter‐ions. Compound 4 stacks with the aid of short interactions between a naphthoquinone O atom of one molecule and the mesityl methyl group of another molecule along the a axis, leading to a one‐dimensional strand that is held together by strong π–η2 interactions between the imidazolium backbone and the [AuCl2]? counter‐ion. The bond angles defined by the AuI atom and two carbene C atoms [C(carbene)—Au—C(carbene)] in compounds 2 and 4 are nearly rectilinear, with an average value of ~174.1 [2]°. Though 2 and 4 share the same cation, they differ in their counter‐anion, which alters the crystal lattice of the two compounds. The knowledge gleaned from these studies is expected to be useful in understanding the molecular interactions of 2 and 4 under physiological conditions. 相似文献
112.
A general route to 2-unsubstituted-1-methoxyindoles, based on our methodology for the synthesis of 1-methoxyindoles, is reported. This synthesis renders accessibility to a variety of natural products possessing the said skeleton. A direct synthesis of phytoalexin (1), (+/-)-paniculidine B (2), and (+/-)-paniculidine C (3) is disclosed based on the methodology. The synthesis of paniculidine B (2) has been achieved from aldehyde 10 in only two steps in 88% yield and in five steps from a methoxyindole compound 8 obtained using our earlier methodology. 相似文献
113.
Let R be a commutative ring with nonzero identity and J(R) the Jacobson radical of R. The Jacobson graph of R, denoted by JR, is defined as the graph with vertex set RJ(R) such that two distinct vertices x and y are adjacent if and only if 1 ? xy is not a unit of R. The genus of a simple graph G is the smallest nonnegative integer n such that G can be embedded into an orientable surface Sn. In this paper, we investigate the genus number of the compact Riemann surface in which JR can be embedded and explicitly determine all finite commutative rings R (up to isomorphism) such that JR is toroidal. 相似文献
114.
Alumina Polished Glassy Carbon Electrode as a Simple Electrode for Lower Potential Electrochemical Detection of Dopamine in its Sub‐micromolar Level 下载免费PDF全文
Balamurugan Thirumalraj Selvakumar Palanisamy Shen‐Ming Chen R. Sayee Kannan 《Electroanalysis》2016,28(3):425-430
The electrochemical behaviour of dopamine (DA) at a cleaned and alumina polished glassy carbon electrode (GCE) was studied using cyclic voltammetry (CV). The CV studies revealed that alumina polished GCE (AGCE) shows an enhanced oxidation peak current response with 217 mV negative potential shift towards DA than that of cleaned GCE. The differential pulse voltammetry result shows that the AGCE detects the DA in the linear concentration ranges from 0.15 to 25.25 µmol L?1. The limit of detection was calculated as 0.046 µmol L?1 with a sensitivity of 3.74 µA µmol L?1 cm?2 for the determination of DA. The fabricated AGCE shows a satisfactory selectivity, practicality along with appreciable repeatability and reproducibility. 相似文献
115.
Mathew Maria J. Selvakumar V.S. Raghunathan Tom Mathews K.S. Nagaraja 《Thermochimica Acta》2008,474(1-2):87-90
The reaction between the magnesium β-diketonate complex Mg(tmhd)2(H2O)2 and 1 equiv. of N,N,N′,N′-tetramethylethylenediamine (tmeda = Me2NCH2CH2NMe2) in hexane at room temperature yielded Mg(tmhd)2(tmeda). The standard enthalpy of sublimation (83.2 ± 2.3 kJ mol−1) and entropy of sublimation (263 ± 6.3 J mol−1 K−1) of Mg(tmhd)2(tmeda) were obtained from the temperature dependence vapour pressure, determined by adopting a horizontal dual arm single furnace thermogravimetric analyser as a transpiration apparatus. From the observed melting point depression DTA, the standard enthalpy of fusion (58.3 ± 5.2 kJ mol−1) was evaluated, using the ideal eutectic behaviour of Mg(tmhd)2(tmeda) as a solvent with bis(2,4-pentanedionato)magnesium(II), Mg(acac)2 as a non-volatile solute. 相似文献
116.
Polypropylene (PP)/Montmorillonite (MMT) nanoclay based composite was prepared by melt compounding with maleic anhydride grafted polypropylene (MA-g-PP) as a compatibilizer in a twin-screw extruder, and the test specimens were injection molded. Mechanical properties such as tensile modulus, flexural modulus, yield strength and maximum percent strains were measured for pure PP and PP based nanocomposite to establish the effect of clay platelet reinforcement. The fracture properties were measured by using the essential work of fracture (EWF) method. PP/clay nanocomposite shows 25% improvement in specific EWF compared to pure PP. The variation of EWF parameters with loading rate is discussed, whilst the mechanisms of fracture are considered in a subsequent paper. 相似文献
117.
118.
P. N. Selvakumar B. Natarajan P. Sambasiva Rao P. Subramanian 《Crystal Research and Technology》2008,43(8):857-862
In order to rationalize the low hyperfine value for the parallel component of copper nucleus, another system with lithium as host has been investigated using Electron Paramagnetic Resonance (EPR) technique. Single crystal EPR studies have been carried out at 300 K on Cu(II) doped glycine lithium sulphate system. Angular variation of hyperfine structure lines in the three orthogonal planes show the presence of two sites which are magnetically inequivalent but chemically equivalent with g and A values as: gxx = 2.084, gyy = 2.057, gzz = 2.311 and Axx = 8.96 mT, Ayy = 3.26 mT, Azz = 15.95 mT respectively. The impurity entered the lattice interstitially. The admixture and molecular coefficients are evaluated by collaborating EPR data with optical data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
119.
Nandini Vallavoju Dr. Sermadurai Selvakumar Dr. Steffen Jockusch Prof. Dr. Mukund P. Sibi Prof. Dr. Jayaraman Sivaguru 《Angewandte Chemie (International ed. in English)》2014,53(22):5604-5608
Can photocatalysis be performed without electron or energy transfer? To address this, organo‐photocatalysts that are based on atropisomeric thioureas and display lower excited‐state energies than the reactive substrates have been developed. These photocatalysts were found to be efficient in promoting the [2+2] photocycloaddition of 4‐alkenyl‐substituted coumarins, which led to the corresponding products with high enantioselectivity (77–96 % ee) at low catalyst loading (1–10 mol %). The photocatalytic cycle proceeds by energy sharing via the formation of both static and dynamic complexes (exciplex formation), which is aided by hydrogen bonding. 相似文献
120.
The title reaction has been surveyed for a number of substrates with differing substitution patterns. With a few exceptions, the methodology provides a one-pot synthesis of the 1,2-diamines from widely available and inexpensive starting materials, and in high yields. In addition, the coupling of 1,4- and 1,3-bis-(N,N,N',N'-tetraalkyl)arylenediamides is shown, under the same experimental conditions, to yield oligomers: R2NC(O)C6H4CH(NR2)-[CH(NR2)C6H4CH(NR2)]n-CH(NR2)C6H4C(O)-NR2 (R = methyl and ethyl; n = 0 to ca. 5). The chemical structures of these unprecedented oligomers are determined by comparison of NMR and MS spectra to those of vicinal diamines, prepared from the analogous N,N-dialkylbenzamides. The origin of the limitation of oligomer chain length is probably due to a specific effect of the internal benzylic amine group, since the substrate 4-Me2NCH2C6H4C(O)NMe2 was found to be uniquely unreactive compared to the other 4-substituted N,N-dialkylbenzamides investigated. N-Methylphthalimide was briefly studied as a monomer and analysis by MS showed that oligomers are formed. Attempts to fully characterize these polymers were unsuccessful. 相似文献