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101.
Delia-Laura Popescu Arani Chanda Matthew Stadler Filipe Tiago de Oliveira Alexander D. Ryabov Eckard Münck Emile L. Bominaar Terrence J. Collins 《Coordination chemistry reviews》2008,252(18-20):2050-2071
Introduced approximately two decades ago, macrocyclic deprotonated tetraamido (4N) and, nearly a decade earlier, acyclic diamidodialkoxido or diamidophenolato (2N/2O) ligand systems have been used, among other things, for the synthesis of a wide variety of high-valent complexes of iron, manganese, cobalt, vanadium, nickel, chromium, and copper. Structural, magnetic, and catalytic properties of these mononuclear, dinuclear, and polynuclear complexes created by the Collins group are reviewed. The present account continues an overview of complexes of this type published recently and devoted to iron species exclusively [Chanda et al., J. Inorg. Biochem., 100 (2006) 606], which provide the first highly effective small molecule mimics of peroxidase enzymes, called TAML activators. The story of the reviewed first-row complexes does not include the diverse and instructive chemistry discovered for osmium, but like the osmium chemistry, it derives its greatest significance from the fact that key members of the various species mark the steps along the design pathway that led to iron-TAML activators. Consideration is given to recent questioning in the literature of the innocence of a TAML system that was designed to be innocent. The reasons underlying the now 15-year old refocusing of our research program on oxidation catalysis and green chemistry with the associated termination of research into designed molecule-based magnetic materials are explained. Our closing contributions from the mid-1990s to the design of molecule-based magnetic materials are reviewed. Previously reported data are discussed in conjunction with newly obtained information on the complexes using density functional theory. 相似文献
102.
Chanda A Shan X Chakrabarti M Ellis WC Popescu DL Tiago de Oliveira F Wang D Que L Collins TJ Münck E Bominaar EL 《Inorganic chemistry》2008,47(9):3669-3678
Recently, we reported the characterization of the S = (1)/ 2 complex [Fe (V)(O)B*] (-), where B* belongs to a family of tetraamido macrocyclic ligands (TAMLs) whose iron complexes activate peroxides for environmentally useful applications. The corresponding one-electron reduced species, [Fe (IV)(O)B*] (2-) ( 2), has now been prepared in >95% yield in aqueous solution at pH > 12 by oxidation of [Fe (III)(H 2O)B*] (-) ( 1), with tert-butyl hydroperoxide. At room temperature, the monomeric species 2 is in a reversible, pH-dependent equilibrium with dimeric species [B*Fe (IV)-O-Fe (IV)B*] (2-) ( 3), with a p K a near 10. In zero field, the M?ssbauer spectrum of 2 exhibits a quadrupole doublet with Delta E Q = 3.95(3) mm/s and delta = -0.19(2) mm/s, parameters consistent with a S = 1 Fe (IV) state. Studies in applied magnetic fields yielded the zero-field splitting parameter D = 24(3) cm (-1) together with the magnetic hyperfine tensor A/ g nbeta n = (-27, -27, +2) T. Fe K-edge EXAFS analysis of 2 shows a scatterer at 1.69 (2) A, a distance consistent with a Fe (IV)O bond. DFT calculations for [Fe (IV)(O)B*] (2-) reproduce the experimental data quite well. Further significant improvement was achieved by introducing hydrogen bonding of the axial oxygen with two solvent-water molecules. It is shown, using DFT, that the (57)Fe hyperfine parameters of complex 2 give evidence for strong electron donation from B* to iron. 相似文献
103.
S Chanda Sarmishtha Bhattacharyya Tumpa Bhattacharjee SS Ghugre Swapan Kumar Basu S Muralithar RP Singh B Mukherjee RK Bhowmik SN Ray 《Pramana》2001,57(1):175-179
The high spin states in N=80 139Pr have been investigated by in-beam γ-spectroscopic techniques following the reaction 130Te (14N, 5n) reaction at E=75 MeV, using a gamma detector array, consisting of seven 23% compton-suppressed high purity germanium detectors and a multiplicity
ball of fourteen bismuth germanate elements. Based on γ-γ coincidence data, the level scheme of 139Pr has been considerably extended up to 7.2 MeV excitation. Tentative spin-parity assignments are done for the newly proposed
levels on the basis of the DCO ratios corresponding to strong gates and the available information from the earlier light ion
experiments. 相似文献
104.
Two sets of nonlinear partial differential equations originating from two different physical situations have been combined
and a new set of nonlinear partial differential equations has been formed wherefrom the previous two sets can be obtained
as particular cases. One of the two sets of equations was obtained by Yang [1] while discussing the condition of self-duality
ofSU(2) gauge fields on Euclidean four-dimensional space. The second one was reported by Charap [2] for the chiral invariant model
of pion dynamics under tangential parametrization. Using the same type of ansatz in each case De and Ray [16] and Ray [7]
obtained physical solutions of the two sets of equations. Here exact solutions of the combined set of equations with particular
values of the coupling constants have been obtained for a similar ansatz. These solutions too are physical in nature. 相似文献
105.
Shyam Sundar Mondal Manosree Chatterjee Ranjay K. Tiwari J.N. Behera Nripen Chanda Sourav Biswas Tanmoy Kumar Saha 《应用有机金属化学》2019,33(8)
A unique hexanuclear zinc(II) ( 1 ) and two mononuclear copper(II) ( 2 and 3 ) complexes anchored with imino phenol ligand HL 1 and HL 2 were synthesized with good yield and purity (where HL 1 = 4‐tert‐butyl‐2,6‐bis((mesitylimino)methylphenol and HL 2 = 5‐tert‐butyl‐2‐hydroxy‐3‐((mesitylimino)methyl)benzaldehyde). These complexes were characterized by utilizing various spectroscopic protocols like NMR, FTIR, UV as well as ESI‐Mass spectrometry, elemental analysis and single crystal X‐ray diffraction studies. Their potential to bind calf thymus DNA (CT‐DNA) was tested utilizing different techniques such as UV–visible and fluorescence spectroscopy. The experiment implies that they interact with CT‐DNA via non‐intercalative mode with moderate capabilities (Kb ~ 104 M?1). On the other hand, these complexes have high capabilities to quench the fluorescence of bovine serum albumin (BSA) following the static pathway. In addition, they are active catalysts for the oxidation reaction of 3,5‐di‐tert‐butylcatechol (3,5‐DTBC) to 3,5‐di‐tert‐butylquinone (3,5‐DTBQ) under aerobic condition. From the recorded EPR signals of all complexes, it has been concluded that the oxidation reaction proceeds via ligand oriented radical pathway instead of metal based redox participation. Kinetic studies using 1 – 3 indicate that it follows Michaelis–Menten type of equation with moderate to high turnover number (kcat). Apart from these aspects, complexes 1 – 3 were screened for their cytotoxic behavior towards HeLa cells (human cervical carcinoma) and found quite active with comparable IC50 values to cisplatin. 相似文献
106.
Tanmoy Chanda Sushobhan Chowdhury B. Janaki Ramulu Suvajit Koley Raymond C.F. Jones Maya Shankar Singh 《Tetrahedron》2014
An operationally simple and highly atom-economic anionic quadruple domino reaction sequence for the synthesis of hexacyclic indeno-fused naphthalene/quinoline molecules having structural resemblance with the C-nor-D-homo-steroid nucleus has been developed. Promoter and solvent specificity, regioselectivity and mechanistic details were experimentally established. Catalyst concentration and solvent dependent switching of domino steps creating four new C–C bonds are discussed. 相似文献
107.
108.
Research on Chemical Intermediates - A novel and robust ionic liquid-supported copper(II) catalyst has been developed and explored for the efficient synthesis of 5-substituted-1H-tetrazoles using... 相似文献
109.
Amadori and Heyns reaction are landmark reactions of carbohydrate chemistry. Synthesis of simple Amadori and Heyns compounds are complicated by various factors and require tedious column chromatographic or ion chromatographic separations. Herein, we report an improved catalytic method based on classical synthetic method of Amadori and Heyns compounds in light of new understanding of a factor governing the reaction. By utilizing the improved catalytic method, we have accomplished several Amadori compounds of d-tagatose and also numerous other Amadori and Heyns compounds. 相似文献
110.
Atomistic molecular dynamics (MD) simulations have been carried out at 30 degrees C on a fully hydrated liquid crystalline lamellar phase of dimyrystoylphosphatidylcholine (DMPC) lipid bilayer with embedded ethanol molecules at 1:1 composition, as well as on the pure bilayer phase. The ethanol molecules are found to exhibit a preference to occupy regions near the upper part of the lipid acyl chains and the phosphocholine headgroups. The calculations revealed that the phosphocholine headgroup dipoles (P- --> N+) of the lipids prefer to orient more toward the aqueous layer in the presence of ethanol. It is noticed that the ethanol molecules modify the dynamic properties of both lipids as well as the water molecules in the hydration layer of the lipid headgroups. Both the in-plane "rattling" and out-of-plane "protrusion" motions of the lipids have been found to increase in the presence of ethanol. Most importantly, it is observed that the water molecules within the hydration layer of the lipid headgroups exhibit faster translational and rotational motions in the presence of ethanol. This arises due to faster dynamics of hydrogen bonds between lipid headgroups and water in the presence of ethanol. 相似文献