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241.
Dr. Dipanwita Das Hemlata Agarwala Dr. Abhishek Dutta Chowdhury Tuhin Patra Dr. Shaikh M. Mobin Prof. Dr. Biprajit Sarkar Prof. Dr. Wolfgang Kaim Prof. Dr. Goutam Kumar Lahiri 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(23):7384-7394
The complex series [Ru(pap)(Q)2]n ([ 1 ]n–[ 4 ]n; n=+2, +1, 0, ?1, ?2) contains four redox non‐innocent entities: one ruthenium ion, 2‐phenylazopyridine (pap), and two o‐iminoquinone moieties, Q=3,5‐di‐tert‐butyl‐N‐aryl‐1,2‐benzoquinonemonoimine (aryl=C6H5 ( 1+ ); m‐(Cl)2C6H3 ( 2+ ); m‐(OCH3)2C6H3 ( 3+ ); m‐(tBu)2C6H3 ( 4 +)). A crystal structure determination of the representative compound, [ 1 ]ClO4, established the crystallization of the ctt‐isomeric form, that is, cis and trans with respect to the mutual orientations of O and N donors of two Q ligands, and the coordinating azo N atom trans to the O donor of Q. The sensitive C? O (average: 1.299(3) Å), C? N (average: 1.346(4) Å) and intra‐ring C? C (meta; average: 1.373(4) Å) bond lengths of the coordinated iminoquinone moieties in corroboration with the N?N length (1.292(3) Å) of pap in 1 + establish [RuIII(pap0)(Q.?)2]+ as the most appropriate electronic structural form. The coupling of three spins from one low‐spin ruthenium(III) (t2g5) and two Q.? radicals in 1 +– 4 + gives a ground state with one unpaired electron on Q.?, as evident from g=1.995 radical‐type EPR signals for 1 +– 4 +. Accordingly, the DFT‐calculated Mulliken spin densities of 1 + (1.152 for two Q, Ru: ?0.179, pap: 0.031) confirm Q‐based spin. Complex ions 1 +– 4 + exhibit two near‐IR absorption bands at about λ=2000 and 920 nm in addition to intense multiple transitions covering the visible to UV regions; compounds [ 1 ]ClO4–[ 4 ]ClO4 undergo one oxidation and three separate reduction processes within ±2.0 V versus SCE. The crystal structure of the neutral (one‐electron reduced) state ( 2 ) was determined to show metal‐based reduction and an EPR signal at g=1.996. The electronic transitions of the complexes 1 n– 4 n (n=+2, +1, 0, ?1, ?2) in the UV, visible, and NIR regions, as determined by using spectroelectrochemistry, have been analyzed by TD‐DFT calculations and reveal significant low‐energy absorbance (λmax>1000 nm) for cations, anions, and neutral forms. The experimental studies in combination with DFT calculations suggest the dominant valence configurations of 1 n– 4 n in the accessible redox states to be [RuIII(pap0)(Q.?)(Q0)]2+ ( 1 2+– 4 2+)→[RuIII(pap0)(Q.?)2]+ ( 1 +– 4 +)→[RuII(pap0)(Q.?)2] ( 1 – 4 )→[RuII(pap.?)(Q.?)2]? ( 1 ?– 4 ?)→[RuIII(pap.?)(Q2?)2]2? ( 1 2?– 4 2?). 相似文献
242.
This article describes a nutrient‐phytoplankton‐zooplankton system with nutrient recycling in the presence of toxicity. We have studied the dynamical behavior of the system with delayed nutrient recycling in the first part of the article. Uniform persistent of the system is examined. In the second part of the article, we have incorporated diffusion of the plankton population to the system and dynamical behavior of the system is analyzed with instantaneous nutrient recycling. The condition of the diffusion driven instability is obtained. The conditions for the occurrence of Hopf and Turing bifurcation critical line in a spatial domain are derived. Variation of the system with small periodicity of diffusive coefficient has been studied. Stability condition of the plankton system subject to the periodic diffusion coefficient of the zooplankton is derived. It is observed that nutrient‐phytoplankton‐zooplankton interactions are very complex and situation specific. Moreover, we have obtained different exciting results, ranging from stable situation to cyclic oscillatory behavior may occur under different favorable conditions, which may give some insights for predictive management. © 2014 Wiley Periodicals, Inc. Complexity 21: 229–241, 2015 相似文献
243.
In Pd-catalyzed arylboronic acid addition to aryl aldehydes, the expected carbinol or asymmetrical ether can be obtained as the major product by altering aqueous solvent composition. Exploiting this methodology with 2-formylbiphenyls as reaction partner, a fluorene scaffold can be readily constructed in two steps. 相似文献
244.
245.
A stereoselective synthesis of the C1–C11 fragment of zincophorin was achieved by using an intramolecular oxetane ring opening reaction as the key step. The oxetane moiety was synthesized by employing a desymmetrization protocol developed at our group and a non-Evans syn aldol as the key steps toward the synthesis. 相似文献
246.
Sisir Lohar Arnab Banerjee Animesh Sahana Sukanya Panja Ipsit Hauli Subhra Kanti Mukhopadhyay Debasis Das 《Tetrahedron letters》2014
Visible light excitable rhodamine B derivative (TARDHD) has been developed for fluorescence and naked eye detection of histidine in aqueous medium. TARDHD shows 45 fold fluorescence enhancement in the presence of histidine. It forms Schiff base with histidine and stabilizes via intra-molecular H-bonding. TARDHD can efficiently detect intracellular histidine. 相似文献
247.
Determination of calcium and iron in silicon and uranium silicide using ion chromatography 总被引:1,自引:0,他引:1
M. K. Das V. V. Raut S. B. Deb S. Jeyakumar M. K. Saxena B. S. Tomar 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(3):1385-1390
Two separate ion chromatography methods were developed for the determination of calcium and iron in silicon and uranium silicide. A cation exchange separation with conductivity detection was developed for Ca. A reversed phase column modified with 50 mM camphor-10-sulphonic acid was used for separating Fe. Iron was detected photometrically. Linear calibrations for Ca (0.1–10 ppm) and Fe (0.5–25 ppm) were performed. Limits of detections for Ca and Fe are 0.03 and 0.2 ppm, respectively. The precision of the methods are better than 2 % for Ca at 0.2 ppm and Fe at 2 ppm. 相似文献
248.
S. Kumar S. U. Kasar R. K. Bajpai C. P. Kaushik R. Guin S. K. Das B. S. Tomar 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(1):45-49
Kinetics of sorption of Pu(IV) by smectite-rich clay has been studied at varying metal ion concentrations. Different concentrations were achieved using different isotopes of Pu, namely, 239Pu, 238Pu and 237Pu. 237Pu was produced by alpha induced reaction on 235U, followed by radiochemical separation of Pu from irradiated U3O8 target. The concentrations used are above and below the solubility of Pu(IV) under neutral pH conditions, thereby, indicating the mechanism of sorption reactions of Pu(IV) in typical laboratory experiments and field level observations. Kinetics of Pu(IV) at 10?13 M concentration was found to be fast whereas at higher metal concentration the rate is governed by a slow step, indicating the role of formation of Pu(IV) polymeric species at the sorbent surface. 相似文献
249.
Linear {NiII–LnIII–NiII} Complexes Containing Twisted Planar Ni(μ‐phenolate)2Ln Fragments: Synthesis,Structure, and Magnetothermal Properties 下载免费PDF全文
Sourav Das Atanu Dey Subrata Kundu Sourav Biswas Prof. Dr. A. J. Mota Prof. Dr. Enrique Colacio Prof. Dr. Vadapalli Chandrasekhar 《化学:亚洲杂志》2014,9(7):1876-1887
Sequential reaction of a multisite LH4 ligand {2‐[2‐hydroxy‐3‐(hydroxymethyl)‐5‐methylbenzylideneamino]‐2‐methylpropane‐1,3‐diol} with appropriate lanthanide salts followed by the addition of Ni(NO3)2 ? 6 H2O in a 4:1:2 stoichiometric ratio in the presence of triethylamine afforded four heterobimetallic trinuclear complexes [Ni2Gd(LH3)4] ? 3 NO3 ? 3 MeOH ? H2O ? CH3CN ( 1 ), [Ni2Tb(LH3)4] ? 3 NO3 ? 3 MeOH ? CH3CN ( 2 ), [Ni2Dy(LH3)4] ? 3 NO3 ? 3 MeOH ? H2O ? CH3CN ( 3 ), and [Ni2Ho(LH3)4] ? 3 NO3 ? 3 MeOH ? H2O ? CH3CN ( 4 ). Complexes 1 – 4 possess linear trimetallic cores with a central lanthanide ion. Magnetic studies revealed a predominant ferromagnetic interaction between the Ni and Ln centers. Alternating current susceptibility measurements of complex 3 showed a small frequency dependence of the out‐of‐phase signal, χ′′M , under zero direct current field, but without achieving a net maximum above 2 K. Magnetic studies on 1 revealed that it has a significant magnetocaloric effect. 相似文献
250.