- 59Co NMR Spectroscopic Chiral Discrimination of 3+ Enantiomers in Ionic Interacting Systems
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Formation of diastereomers of Δ- and Λ-3+ was investigated in aqueous chiral-electrolyte solutions using 59Co NMR spectroscopy.The chiral electrolytes used were alkali salts for L- and D-tartrates, bis(μ-(-)589-tartrato)diantimonate(III), N-dodecanoyl-L-(and D-)alaninate, N-dodecanoyl-L-threoninate, and N-hexadecanoyl-L-prolinate.The 59Co NMR parameters for the 3+ group were different between the enantiomers in most cases.The NMR parameters used for chiral discrimination were chemical shifts (in simple electrolyte and micellar solutions), ralaxation rates (in simple electrolyte and micellar solutions), peak areas (in micellar solutions), and quadrupole splittings (in liquid crystalline solutions).The larger values of the relaxation rates suggest stronger interactions.On the other hand, the magnitude of the chemical shift change was not simply related to the extent of the interactions.For a chemical shift, the contribution of a geometrical factor seems to be dominant in systems having local anisotropy in the interaction.
- Iida, Masayasu,Mizuno, Yuri,Koine, Norio
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- Sonochemical synthesis, characterization, antimicrobial activity and textile dyeing behavior of nano-sized cobalt(III) complexes
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Using ultrasonic irradiations, nano-sized cobalt(III) coordination complexes, [Co(NH3)6]Cl3·2H2O (A), [Co(en)3]Cl3·3H2O (B) (en-ethylenediamine) and [Co(dien)2]Cl3·3.5H2O (C) (dien-diethylenetriamine) were synthesized. These complexes were characterized by spectroscopic studies like IR, UV/Visible and NMR. Morphology of these complexes was determined by SEM and particle size with the help of TEM & Zeta-sizer. The comparative thermal stability along with phase difference between nano structures and their respective bulk complexes has been studied by thermal gravimetric analysis (TGA) and X-ray powder diffraction (XRD) study respectively. The dyeing behavior of nano-sized Co(III) complexes and their respective bulks has also been studied (using both exhaust and pad dyeing methods) on cotton and wool fabrics and results shown rationalized dyeing behavior. All these complexes were further tested for antimicrobial activity (against B. subtilis, E. coli, K. pneumoniae, F. oxysporum and A. alternate) and it was observed that nano sized complexes enhanced the activity further.
- Bala, Ritu,Behal, Jagriti,Kaur, Varinder,Jain, Subheet Kumar,Rani, Riveka,Manhas, Rajesh Kumari,Prakash, Vinit
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- Magnetic properties of nanocrystalline é-Fe3N and Co 4N phases synthesized by newer precursor route
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Nanocrystalline é-Fe3N and Co4N nitride phases are synthesized first time by using tris(1,2-diaminoethane)iron(II) chloride and tris(1,2-diaminoethane)cobalt(III) chloride precursors, respectively. To prepare é-Fe3N and Co4N nitride phases, the synthesized precursors were mixed with urea in 1:12 ratio and heat treated at various temperatures in the range of 450-900 C under the ultrapure nitrogen gas atmosphere. The precursors are confirmed by FT-IR study. The é-Fe 3N phase crystallizes in hexagonal structure with unit cell parameters, a = 4.76 ? and c = 4.41 ?. The Co4N phase crystallizes in face centred cubic (fcc) structure with unit cell parameters, a = 3.55 ?. The estimated crystallite size for é-Fe3N and Co4N phases are 29 nm and 22 nm, respectively. The scanning electron microscopy (SEM) studies confirm the nanocrystalline nature of the materials. The values of saturation magnetization for é-Fe3N and Co 4N phases are found to be 28.1 emu/g and 123.6 emu/g, respectively. The reduction of magnetic moments in ultrafine materials compared to bulk materials have been explained by spin pairing effect, lattice expansion, superparamagnetic behaviour and canted spin structures at the surface of the particles.
- Theerthagiri,Dalavi, Shankar B.,Manivel Raja,Panda
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- EXAFS investigations of temperature-dependent structure in cobalt-59 molecular NMR thermometers
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Cobalt-59 nuclei are known for extremely thermally sensitive chemical shifts (δ), which in the long term could yield novel magnetic resonance thermometers for bioimaging applications. In this manuscript, we apply extended X-ray absorption fine structure (EXAFS) spectroscopy for the first time to probe the exact variations in physical structure that produce the exceptional thermal sensitivity of the 59Co NMR chemical shift. We apply this spectroscopic technique to five Co(iii) complexes: [Co(NH3)6]Cl3 (1), [Co(en)3]Cl3 (2) (en = ethylenediamine), [Co(tn)3]Cl3 (3) (tn = trimethylenediamine), [Co(tame)2]Cl3 (4) (tame = 1,1,1-tris(aminomethyl)ethane), and [Co(diNOsar)]Cl3 (5) (diNOsar = dinitrosarcophagine). The solution-phase EXAFS data reveal increasing Co-N bond distances for these aqueous complexes over a ~50 °C temperature window, expanding by Δr(Co-N) = 0.0256(6) ?, 0.0020(5) ?, 0.0084(5) ?, 0.0006(5) ?, and 0.0075(6) ? for 1-5, respectively. Computational analyses of the structural changes reveal that increased connectivity between the donor atoms encourages complex structural variations. These results imply that rich temperature-dependent structural variations define 59Co NMR thermometry in macrocyclic complexes.
- Campanella, Anthony J.,Ozvat, Tyler M.,Rappé, Anthony K.,Sterbinsky, George E.,Zadrozny, Joseph M.
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supporting information
p. 16380 - 16385
(2020/12/03)
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- Gas-conforming transformability of an ionic single-crystal host consisting of discrete charged components
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(Figure Presented) Dynamic accommodation: The racemic crystal of (±)-[Co(en)3]Cl3 (en = ethylenediamine; see space-filling model of lattice: Co red, N blue, Cl green, C gray) includes H2O molecules within the one-dimensional channels when hydrated. Upon removal of the H2O molecules by vacuum drying, the crystal exhibits dynamic behavior as a host to a variety of light gases or organic vapors within its channels by expansion/contraction of the lattice while single-crystal properties are maintained.
- Takamizawa, Satoshi,Akatsuka, Takamasa,Ueda, Takahiro
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p. 1689 - 1692
(2009/02/06)
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- Kinetic analyis of TF data, XXXV. Spectroscopic and thermal studies of some cobalt(III) chelates with ethylenediamine
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A number of 30 [Co(en)3]Y3, [Co(en)2X2]Y and [Co(en)2X(amine)]Y2 type complexes (X=Cl, Br; Y=Cl, Br, I, NCO, NCS, NO3, ClO4, etc.; amine=aromatic and alkylamines) were obtained from trans-[Co(en)2Cl2]Cl by double decomposition and by substitution reactions, respectively. The structure of the complexes was proved by means of far and middle FTIR spectra. The thermal decomposition was studied by TG, DTA and DSC measurements. Mass spectra were also recorded. In the case of [Co(en)3]Y3 complexes the nitrate, perchlorate and dimesoperiodates decompose suddenly, frequently explosion like. The halides and thiocyanates seem to substitute an ethylenediamine ligand, yielding a rather unstable intermediate. The pyrolysis of [Co(en)2X2]Y type derivatives yields no relatively stable intermediates, but the decomposition temperatures may be correlated with the nature of Y and with the cis or trans configuration of the compound. With the [Co(en)2X(amine)]Y2 type complexes one observes the formation of [Co(en)2XY]Y as intermediate product. From the TG curves kinetic parameters were derived for some dehydration and deamination processes, by using the nomogram method. The validity of a nonlinear kinetic compensation law was observed.
- Zsako,Pokol,Novak,Varhelyi,Dobo,Liptay
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p. 843 - 856
(2008/10/08)
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- The infra-red spectrum of Cl3*3T2O (en:ethylenediamine)
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The infra-red spectrum of Cl3*2T2O has been observed over a period of 5 months.The spectrum changes considerably even in 2 days after preparation of the hydrate, revealing quite different features from the parent.Initially some bands due to the NH2 group disappear, while new bands appear.These are explained in terms of a change in bonding character or as an interaction between the complex ion and the chloride anion in the crystal.Subsequently, the bands due to ethylenediamine decrease in intensity and almost vanish, while additional new bands appear.The new bands are explained in terms of amine complexes.It is proposed that a decomposition reaction of takes place through intermediates such as vinylamine and so on.After one month the spectrum still changes slowly with further new bands due to a H-T exchange reaction.
- Kaneasaka, Isao,Nishimura, Hiroyuki,Kanamori, Kan,Kawai, Kiyoyasu,Ichimura, Kenji,Watanabe, Kuniaki
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p. 817 - 822
(2007/10/02)
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