http://nopr.niscair.res.in/handle/123456789/10981 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/11018 Title: Heteroatom effect on intramolecular double proton transfer of 3,6-diiminocyclohexa-1,4-diene-1,4-diamine: A<i> </i>theoretical study <br/> <br/>Authors: Tahermansouri, Hasan; Moradi, Shahram; Sayyadi, Robabeh <br/> <br/>Abstract: The process of intramolecular proton transfer in 3,6-diiminocyclohexa-1,4-diene-1,4-diamine&nbsp; and some hetero derivatives has been investigated at HF and DFT (B3LYP) levels of theory in two states, concerted and stepwise. In 3,6-diiminocyclohexa-1,4-diene-1,4-diamine, the energy barrier for the proton transfer through concerted and stepwise mechanism is found to be ~ 27 and 17 kcal/mol, respectively. When replacing two CH groups by two boron atoms in the ring (3,6-dihydro-3,6-diimino-1,4-diborinine-2,5-diamine), the obtained energy barriers are ~ 48 and 26 kcal/mol, respectively. The values obtained on replacing the CH groups by two atoms of nitrogen, silicon and phosphor are ~30 and 18 kcal/mol (3,6-dihydro-3,6-diiminopyrazine-2,5-diamine), 86 and 45 kcal/mol (3,6-dihydro-3,6-diimino-1,4-disiline-2,5-diamine) and 84 and 45 kcal/mol (3,6-dihydro-3,6-iimino-1,4-diphosphinine-2,5-iamine) respectively. The displacement pathway and the resonance forms that are produced in the conversion processes have been investigated. The nucleus-independent chemical shift methodology has been applied to study the charge distributions in the ring. <br/> <br/>Page(s): 180-184 http://nopr.niscair.res.in/handle/123456789/11017 Title: Synthesis of nickel nanoparticles with fcc and hcp crystal structures <br/> <br/>Authors: Raj, K Joseph Antony; Viswanathan, B <br/> <br/>Abstract: Nickel nanoparticles have been synthesized using nickel nitrate, vegetable oil and sucrose. Ethanol has been used as a solvent since the heat of reaction shows the destabilization of nickel particles if water is present in the synthesis mixture. Nickel with fcc phase is obtained by reduction with sucrose followed by stabilization using vegetable oil. Nickel or possibly nickel carbide with hcp structure is obtained by treatment with a mixture of oleylamine and methanol. The fcc and hcp crystal structures have been characterized by XRD. The calcination of nickel nanoparticles at 450 °C results in the sintering of nickel nanoparticles, thereby increasing the crystallite size. The scanning electron micrograph reveals that the particle size is in the range of 5 – 58 nm for fcc-Ni nanoparticles calcined at 450 °C for 10 min. <br/> <br/>Page(s): 176-179 http://nopr.niscair.res.in/handle/123456789/11016 Title: Effect of an ancillary ligand on single helix-double helix interconversion in copper complexes. Copper(I)-water bond <br/> <br/>Authors: De, Senjuti; Chowdhury, Shubhamoy; Drew, Michael G B; Datta, Dipankar <br/> <br/>Abstract: Reaction of Cu(ClO₄)₂.6H₂O with the 1:2 condensate of benzildihydrazone and 2-acetylpyridine, in methanol in equimolar ratio yields a green compound which upon recrystallisation from 1:1 CH₂Cl₂-C₆H₆ mixture affords [CuL(H₂O)](ClO₄)₂.½C₆H₆. The complex crystallises in the space group  P-1 with <i style="">a</i> = 8.028(11) Å, <i style="">b</i> = 12.316(17) Å, <i style="">c </i>= 18.14(3) Å, <i><img src='/image/spc_char/alpha.gif' border=0></i> = 97.191(10)^o, <i><img src='/image/spc_char/beta.gif' border=0></i> = 94.657(10)^o and <i><img src='/image/spc_char/gamma.gif' border=0></i> = 108.039(10)^o. It is single helical with the metal having a distorted trigonal bipyramidal N₄O coordination sphere. The acid dissociation constant of the Cu(I) complex in CH₃CN is 3.34 ± 0.19. The X band EPR spectrum of the compound is rhombic with <i>g</i>₁ = 2.43, <i>g</i>₂ = 2.10, <i>g</i>₃ = 2.02 and <i style="">A</i>₁ = 79.3 x 10^-4 cm^-1. The Cu(II/I) potential of the complex in CH₂Cl₂ at a glassy carbon electrode is 0.43 V vs SCE. It is argued that the copper-water bond persists in the corresponding copper(I) species. Its implications on the single helix-double helix interconversion in copper helicates are discussed. DFT calculations at the B3LYP/ 6-311G** level shows that the binding energy of water in the single helical five-coordinate copper(I) species [CuL(H₂O)]⁺ is ~ 40 kJ mol^-1. <br/> <br/>Page(s): 171-175 http://nopr.niscair.res.in/handle/123456789/11015 Title: Photodegradation of carboxylic acids on Al₂O₃ and SiO₂ nanoparticles <br/> <br/>Authors: Karunakaran, C; Dhanalakshmi, R; Manikandan, G; Gomathisankar, P <br/> <br/>Abstract: Al₂O₃ and SiO₂ nanoparticles effect photodegradation of carboxylic acids, and their photonic efficiencies are comparable to those of TiO₂ P25 Degussa, TiO₂ Hombikat, TiO₂ anatase, TiO₂ rutile, ZnO, SnO₂, and ZrO₂ nanosemiconductors. All the nanoparticles show sustainable photoactivity and the degradation rates increase linearly with oxalic acid-concentration and photon flux. The photonic efficiencies of degradation are in the order: formic acid > oxalic acid > acetic acid > citric acid. The mechanism of photodegradation is discussed. <br/> <br/>Page(s): 163-170