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Venkataramanan N.S.,Institute of Materials Research IMR | Sahara R.,Institute of Materials Research IMR | Mizuseki H.,Institute of Materials Research IMR | Kawazoe Y.,Institute of Materials Research IMR
Computational Materials Science | Year: 2010

We have demonstrated that doping alkali cations in charged state can improve the hydrogen adsorption significantly in the molecular form. In addition, the number of hydrogen molecules adsorbed by Li cation doped benzene system was 3 while Na and K doped benzene were able to adsorb up to 6 hydrogen molecules. In general the adsorption energies of alkali atoms and the binding energy/H 2 for hydrogen are underestimated by the hybrid B3LYP functional, while MP2 functional provides higher binding energy. The nature of interaction between hydrogen and the alkali center was mainly due to be dipole - quardupole and dipole - induced dipole electrostatic interaction. Further, we extended the present single benzene system to the curved calixarene system. The calixarene ring was able to adsorb up to five alkali atoms, one inside the cavity and 4 on the walls of the cavity and this system was capable to adsorb up to 30 H 2 molecules in molecular form at low temperature. © 2010 Elsevier B.V. All rights reserved.

Venkataramanan N.S.,Institute of Materials Research IMR | Suvitha A.,Institute of Materials Research IMR | Nejo H.,Japan National Institute of Materials Science | Mizuseki H.,Institute of Materials Research IMR | Kawazoe Y.,Institute of Materials Research IMR
International Journal of Quantum Chemistry | Year: 2011

DFT and TDDFT calculations at the level of PBE0/6-31G(d)/6-31+G(d) were performed systematically on seven porphyrins with symmetrical meso-substitutents. Our results show that the planarity of the free base porphyrin (BP) are affected by the introduction of substitutents at the meso-position of the ring. Geometrical studies show that the introduction of electron-withdrawing groups brings about in-plane deformation in the porphyrin ring, whereas the bulky substitutents make an out-of-plane deformation. However, FMO's diagram shows that electron-withdrawing groups alter the degeneracy of the HOMO and HOMO -1 orbtial. Up on introduction of substituents at the meso-position, the Q band FMOs transitions were the same as in the case of free BP; however, the oscillator strength is changed. Electron releasing substituted at the meso-position shows bathochromic shift in the Q band region. However, the intensity or the hyperchromic shift is higher for the electron withdrawing groups. Solvation studies show that Q bands are blue shifted and B bands are red shifted, whereas the intensity of the B bands was highly enhanced compared with the Q bands. These theoretical studies would be helpful in designing new porphyrins for the photodynamic therapy and dye-sensitized solar cell applications. © 2009 Wiley Periodicals, Inc.

Spirkova M.,Czech Institute of Macromolecular Chemical | Duszova A.,Institute of Materials Research IMR | Poreba R.,Czech Institute of Macromolecular Chemical | Kredatusova J.,Czech Institute of Macromolecular Chemical | And 3 more authors.
Composites Part B: Engineering | Year: 2014

The series of polyurethane - carbon nanofiber (PU/CNF) elastomers was prepared and characterized. Polyurethane elastomeric matrix was made from polybutadiene-based macrodiol of MW ca. 2000, 1,6-diisocyanatohexane, and butane-1,4-diol. Carbon nanofibers (up to 2.25 wt.%) were dispersed in the mixture of monomers, i.e., before polyurethane formation. The influence of the nanofiber concentration on functional properties was studied by the series of microscopic, thermal, mechanical and electrical techniques of analysis. The best functional properties has PU/CNF composite containing 0.75 wt.% of CNF. © 2014 Elsevier Ltd. All rights reserved.

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