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51.
Ambarish Ray Dipankar Maity Anup Pramanik Kalyan K. Das Mahasweta Nandi Asim Bhaumik M. Nethaji Swastik Mondal Monika Mukherjee Mahammad Ali 《Polyhedron》2009,28(17):3659-3666
Two new copper(II) complexes, [Cu2(L1)2](ClO4)2 (1) and [Cu(L2)(ClO4)] (2), of the highly unsymmetrical tetradentate (N3O) Schiff base ligands HL1 and HL2 (where HL1 = N-(2-hydroxyacetophenone)-bis-3-aminopropylamine and HL2 = N-(salicyldehydine)-bis-3-aminopropylamine) have been synthesised using a template method. Their single crystal X-ray structures show that in complex 1 two independent copper(II) centers are doubly bridged through phenoxo-O atoms (O1A and O1B) of the two ligands and each copper atom is five-coordinated with a distorted square pyramidal geometry. The asymmetric unit of complex 2 consists of two crystallographically independent N-(salicylidene)-bis(aminopropyl)amine-copper(II) molecules, A and B, with similar square pyramidal geometries. Cryomagnetic susceptibility measurements (5–300 K) on complex 1 reveal a distinct antiferromagnetic interaction with J = ?23.6 cm?1, which is substantiated by a DFT calculation (J = ?27.6 cm?1) using the B3LYP functional. Complex 1, immobilized over highly ordered hexagonal mesoporous silica, shows moderate catalytic activity for the epoxidation of cyclohexene and styrene in the presence of TBHP as an oxidant. 相似文献
52.
Vikas Kumar Mehak Gupta Sumit G. Gandhi Sonali S. Bharate Ajay Kumar Ram A. Vishwakarma Sandip B. Bharate 《Tetrahedron letters》2017,58(42):3974-3978
Herein we report isolation of a new chromone alkaloid chrotacumine K (12) from fruits and a chromone glycoside schumaniofioside A (13) from leaves of Dysoxylum binectariferum Hook f. Schumaniofioside A is reported for the first time from Meliaceae family. Other known alkaloids isolated include rohitukine (1) and chrotacumine E (6). The structure of new alkaloid 12 was elucidated on the basis of extensive 1D and 2D NMR analysis, synthesis and chemical hydrolysis. Chemically, chrotacumine K (12) is a 3′-O-acetyl rohitukine which on chemical or enzymatic hydrolysis produces rohitukine. The new alkaloid 12 is also present in seeds and stem-barks of this plant. The glycoside schumaniofioside A (13) is present only in leaves, and in abundance (~1% w/w of dried leaves). The isolated compounds and extracts were evaluated for in vitro effect on the proinflammatory cytokines (TNF-α and IL-6) in human monocytic THP-1 cells. The alkaloid 12 displayed potent inhibition (57%) of TNF-α at 0.3 µM, and was non-toxic to THP-1 cells up to 40 µM, indicating its excellent therapeutic window. Furthermore, a nitrobenzoyl ester analog 15e showed better inhibition of IL-6 than parent natural product chrotacumine K. 相似文献
53.
Lalit Giri Arun Kumar Jugran Amit Bahukhandi Praveen Dhyani Indra D. Bhatt Ranbeer Singh Rawal Shyamal Kumar Nandi Uppeandra Dhar 《Applied biochemistry and biotechnology》2017,181(1):267-282
Habenaria edgeworthii Hook. f. ex Collett is an important terrestrial orchid used in different Ayurvedic formulations. In the present study, variations among morphological, phytochemical and molecular markers were assessed. A significant difference was observed among populations using morphological traits. Inter-simple sequence repeat (ISSR) data revealed lower genetic diversity at population level (He = 0.207) as compared to species level (He = 0.334). Analysis of molecular variance (AMOVA) indicates 74 % variation among populations and 26 % within population. Tuber extracts showed significantly (p < 0.05) higher total phenolics and flavonoids among the populations. Antioxidant activity determined by 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays exhibited considerable antioxidant potential. Furthermore, the associations between molecular and morphological and phytochemical attributes were studied using multiple regression analysis (MRA). Several ISSR fragments were associated with some morphological and phytochemical traits. These ISSR fragments can be useful for breeding programme of the species when no other genetic information, such as linkage maps and quantitative trait loci, is available. 相似文献
54.
Chemical oscillation is an interesting nonlinear dynamical phenomenon which arises due to complex stability condition of the steady state of a reaction far away from equilibrium which is usually characterised by a periodic attractor or a limit cycle around an interior stationary point. In this context Lienard equation is specifically used in the study of nonlinear dynamical properties of an open system which can be utilized to obtain the condition of limit cycle. In conjunction with the property of limit cycle oscillation, here we have shown the condition for isochronicity for different chemical oscillators with the help of renormalisation group method with multiple time scale analysis from a Lienard system. When two variable open system of equations are transformed into a Lienard system of equation the condition for limit cycle and isochronicity can be stated in a unified way. For any such nonlinear oscillator we have shown the route of a dynamical transformation of a limit cycle oscillation to a periodic orbit of centre type depending on the parameters of the system. 相似文献
55.
Four new neutral copper-azido polymers [Cu(6)(N(3))(12)(aem)(2)](n)(1), [Cu(6)(N(3))(12)(dmeen)(2)(H(2)O)(2)](n) (2), [Cu(6)(N(3))(12)(N,N'-dmen)(2)](n) (3), and [Cu(6)(N(3))(12)(hmpz)(2)](n) (4) [aem = 4-(2-aminoethyl)morpholine; dmeen = N,N-dimethyl-N'-ethylethylenediamine; N,N'-dmen = N,N'-dimethylethylenediamine and hmpz = homopiperazine] have been synthesized by using 0.33 mol equiv of the chelating diamine ligands with Cu(NO(3))(2)·3H(2)O/CuCl(2)·2H(2)O and an excess of NaN(3). Single crystal X-ray structures show that the basic unit of these complexes, especially 1-3, contains very similar Cu(II)(6) building blocks. But the overall structures of these complexes vary widely in dimensionality. While 1 is three-dimensional (3D) in nature, 2 and 3 have a two-dimensional (2D) arrangement (with different connectivity) and 4 has a one-dimensional (1D) structure. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit dominant ferromagnetic behavior in all the four complexes. The experimental susceptibility data have been analyzed by some theoretical model equations. 相似文献
56.
Sandip R. Sabale D. V. Jadhav B. S. Mohite 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):273-278
A simple and efficient column chromatographic method has been developed for the sequential separation of U(VI), Th(IV) and
Ce(III) using poly[dibenzo-18-crown-6] as stationary phase and l-arginine as a counter ion. The different elution patterns with various eluting agents were observed for individual element.
The capacity of poly[dibenzo-18-crown-6] for U(VI), Th(IV) and for Ce(III) was found to be 0.96, 0.86 and 1.49 (±0.01) mmol/g
of crown polymer, respectively. The method is efficient to separate the elements in multicomponent mixtures and has good recovery.
The method is extended to determine the U(VI), Th(IV) and Ce(III) from monazite sand. The method is simple, rapid and selective
having good reproducibility (~±2%). 相似文献
57.
Andrzej Rajca Prof. Velavan Kathirvelu Dr. Sandip K. Roy Dr. Maren Pink Dr. Suchada Rajca Dr. Santanu Sarkar Sandra S. Eaton Prof. Gareth R. Eaton Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(19):5778-5782
Site‐directed spin labeling and EPR spectroscopy offer accurate, sensitive tools for the characterization of structure and function of macromolecules and their assemblies. A new rigid spin label, spirocyclohexyl nitroxide α‐amino acid and its N‐(9‐fluorenylmethoxycarbonyl) derivative, have been synthesized, which exhibit slow enough spin‐echo dephasing to permit accurate distance measurements by pulsed EPR spectroscopy at temperatures up to 125 K in 1:1 water/glycerol and at higher temperatures in matrices with higher glass transition temperatures. Distance measurements in the liquid nitrogen temperature range are less expensive than those that require liquid helium, which will greatly facilitate applications of pulsed EPR spectroscopy to the study of structure and conformation of peptides and proteins. 相似文献
58.
Density functional calculations have been carried out to obtain low energy equilibrium geometries of anionic and neutral sodium clusters over a wide range of sizes 40 ≤ N ≤ 147, where N is the number of atoms. An exhaustive search for the low energy equilibrium geometries has been carried out. The density of states of the lowest energy geometries are compared with the experimental photoelectron spectra (Huber et al 2009 Phys. Rev. B 80 235425; Kostko et al 2007 Phys. Rev. Lett.98 043401) for N > 41. The agreement between theory and experiment is good for almost all the clusters and the changes in the spectrum with size correlate very well with the changes in the shapes as observed in the evolutionary trend of the ground state geometries. 相似文献
59.
A convenient and highly efficient method for the synthesis of novel polyheterocyclic chromeno pyrimido[1,2-b]indazolone derivatives via a three-component condensation of 1H-indazol-3-amine, aldehydes and 4-hydroxycoumarin catalyzed by Bronsted acid ionic liquid [Et3NH][HSO4] under solvent-free reaction conditions is presented. This ionic liquid is air and water stable and easy to prepare from amine and acid. The main advantages of this protocol includes short reaction time, excellent yield, easy work-up, operational simplicity, a wide range of functional group tolerance and column chromatography-free method. The catalyst can be recovered and reused for at least four runs without any significant impact on the product yields. 相似文献
60.
Gao J Yu A Itkis ME Bekyarova E Zhao B Niyogi S Haddon RC 《Journal of the American Chemical Society》2004,126(51):16698-16699
Aligned single-walled carbon nanotubes (SWNTs) and hierarchical SWNT assembly were fabricated by electrospinning. The high fiber elongation and high DC electric field applied during the electrospinning process result in the orientation of the SWNTs along the axial direction of the fiber. The alignment of the electropsun composite fiber transfers this local SWNT orientation to macroscopically aligned SWNTs. After removing the polymer component from the aligned composite fiber, we produced large area aligned SWNTs. The results show that the directional control of SWNT alignment and debundling of SWNTs into individual tubes can be simultaneously realized. 相似文献