http://nopr.niscair.res.in/handle/123456789/59 Fri, 30 Jun 2017 09:36:41 GMT 2017-06-30T09:36:41Z http://nopr.niscair.res.in/handle/123456789/42318 Title: Electrochemistry of binary and mixed-ligand copper(II) complexes with pyrazine and dicyanamide bridging ligands in aqueous medium Authors: Prakash, Ved; Srivastava, Krishna; Prasad, Jagdish Abstract: The binary copper(II) complexes, viz., [Cu(II) (pyz)_n(H₂O)_n] (<b>1</b>), and [Cu(II)(dca)_n(H₂O)_n] (<b>2</b>), and, mixed ligand complex, [Cu(II) (dca)_n(pyz)_n]. nH₂O (<b>3</b>), containing pyrazine (pyz) and dicyanamide (dca) bridging ligands (where n is number of ligand attached and it could be 1 to 6 ) are formed in aqueous medium. The electrochemical behavior of binary complexes in 1:1, 1:2 and 1:10 (Cu : pyz/dca) molar ratios and mixed ligand complex in 1: 1 :1 and 1:2:1 (Cu:dca:pyz) molar ratios have been carried out by cyclic voltammetry. The binary complex <b>1</b> undergoes a quasi-reversible single-electron redox process (Cu^2+/+), while the binary complex<b> 2</b> exhibits a totally irreversible reduction peak involving two electrons corresponding to Cu^2+/0 change. The reduction potential becomes positive with increasing concentration of pyz/or dca, clearly indicating that reduction becomes easier with increasing concentration of ligand in binary complexes. The mixed ligand complex <b>3</b> involving pyz and dca bridging ligands shows an irreversible reduction peak assigned to Cu^2+/0 electrode reactions. The UV-vis spectral properties of all the binary and mixed ligand complexes have been studied in aqueous medium. Page(s): 585-591 Thu, 01 Jun 2017 00:00:00 GMT http://nopr.niscair.res.in/handle/123456789/42318 2017-06-01T00:00:00Z http://nopr.niscair.res.in/handle/123456789/42317 Title: Synthesis of α-Fe₂O₃ nanoparticles via wet high-energy ball-milling and its catalytic application in thermal decomposition of ammonium perchlorate Authors: Hosseini, Seyed Ghorban; Ayoman, Esmaeil; Ghavi, Azam Abstract: α-Fe₂O₃ nanoparticles have been successfully produced by the wet high-energy ball-milling method.Phase and nanostructure characterizations of as-crushed powders have been done by X-ray diffraction and field emission scanning electron microscopy techniques.Average particle sizes of 56 and 51 nm are obtained after 20 and 40 hours of wet ball milling process, respectively.The catalytic property of the synthesised α-Fe₂O₃ nanoparticles in the thermal decomposition reaction of ammonium perchlorate has been evaluated by thermogravimetry and differential scanning calorimetry. Thermal analysis confirms thatadding 5 wt.% α-Fe₂O₃ nanoparticles (51 nm) decreases the decomposition temperature of ammonium perchlorate from 422.0 °C to 360.0 °C and increases the Δ<i>H</i> of the decomposition reaction from 880 J g^-1 to 1408.1 J g^-1.Finally, the catalytic effects of α-Fe₂O₃ NPs on kinetic and thermodynamic parameters of thermal decomposition reaction of treated AP particles have been studied by Kissinger, Boswell, Ozawa and Starink methods. Page(s): 592-600 Thu, 01 Jun 2017 00:00:00 GMT http://nopr.niscair.res.in/handle/123456789/42317 2017-06-01T00:00:00Z http://nopr.niscair.res.in/handle/123456789/42316 Title: Synthesis, structure and properties of a hexarubidium heptamolybdate with bridging aqua ligands Authors: Srinivasan, Bikshandarkoil R; Morajkar, Sudesh M; Khandolkar, Savita S; Näther, Christian; Bensch, Wolfgang Abstract: The synthesis, single crystal structure, spectral, thermal and electrical properties of a hexarubidium heptamolybdate [Rb₆(H₂O)₄(Mo₇O₂₄)]<b> 1</b> is reported. The bridging binding modes of the unique (Mo₇O₂₄)^6- ion and the four crystallographically independent coordinated water molecules results in coordination numbers ranging from 8 to 10 for the six unique Rb(I) ions in <b>1</b>. Thermal decomposition of <b>1</b> results in the formation of an anhydrous residue of composition 7MoO₃·3Rb₂O. The cyclic voltammogram of an aqueous solution of <b>1</b> exhibits a single redox event characteristic of (Mo₇O₂₄)^6- anion. Solution conductivity studies reveal the presence of hydrated Rb⁺ cations and uncoordinated (Mo₇O₂₄)^6-anions. A comparative study of several alkali-metal heptamolybdates reveals a rich structural chemistry in terms of the binding modes of the (Mo₇O₂₄)^6- anion. Page(s): 601-609 Thu, 01 Jun 2017 00:00:00 GMT http://nopr.niscair.res.in/handle/123456789/42316 2017-06-01T00:00:00Z http://nopr.niscair.res.in/handle/123456789/42315 Title: Tuning the tripodal rotational barrier in η⁶- chromiumtricarbonyl heteroarenes – A step towards torsional switches Authors: Kalpana, A; Akilandeswari, L Abstract: The current work focuses on manifold magnification of tripodal rotational barrier of Cr(CO)<sub >3</sub> which is haptotropically bound to the arene ring with variety of hetero substitution (boron/phosphorus). The study shows that the differential electronegativities of boron and phosphorus can be harnessed to manipulate the torsional barrier, enabling hundred 200-fold enhancement of barrier to nearly free tripodal rotation of Cr(CO)<sub >3</sub> in arene moiety. Insights obtained by density functional studies are supported by natural bond orbital analysis. Page(s): 610-615 Thu, 01 Jun 2017 00:00:00 GMT http://nopr.niscair.res.in/handle/123456789/42315 2017-06-01T00:00:00Z