Rommel B. Viana

Publications (16) View all

• Article: 4-Hydroxy-2,5-dimethylphenyl-benzophenone: Conformational stability, FT-IR and Raman investigation.

  Rommel B Viana, Evania D A Santos, Leidy J Valencia, Rivelino M Cavalcante, Edson B Costa, Rodolfo Moreno-Fuquen, Albérico B F da Silva
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  ABSTRACT: In this paper we have studied the 4-hydroxyl-2,5dimethylphenyl-benzophenone. Also, it was analyzed the vibrational assignment (FT-IR and Raman) in conjunction with computational results. The conformational analysis showed three barrier heights where two are due to the dihedral rotation and the other one is attributed to hydroxyl rotation. While the high dihedral rotational barrier (TS1) is 6.06-7.22kcalmol(-1), the lower one (TS2) is almost three times smaller. The variations with the change of basis set is 5-8% to TS1, and 3-15% in the values predicted to TS2. In the case of OH rotational barrier, the values range from 3.70 to 4.86kcalmol(-1), and it is also observed that this transition state is less sensitive to the change of basis set and to the method. Two isomers was detected due to the changes in the OH rotation with the gap energy lower than 0.7kcalmol(-1), and at this point is seen that semi-empirical methods fail into describe the most stable conformation which may be due to the small energy gap. The enthalpy formation at 0K and 298K was 111.71 and 102.20kcalmol(-1), respectively.
  Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 10/2012; 102C:386-392. · 2.10 Impact Factor
• Source

  Available from: Ronaldo do Ferreira Nascimento

  Article: Risk assessment of trihalomethanes from tap water in Fortaleza, Brazil

  Rommel B. Viana, Rivelino M. Cavalcante, Fuad M. G. Braga, Anderson B. Viana, José C. de Araujo, Ronaldo F. Nascimento, André S. Pimentel
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  ABSTRACT: The cancer risks (CR) by oral ingestion, dermal absorption, and inhalation exposure of trihalomethanes (THM) from tap water of ten districts in Fortaleza, Brazil were estimated. The mean levels of THM compounds were obtained in Fortaleza tap water as follow: 63.9μg L−1 for chloroform (CHCl3), 40.0μg L−1 for bromodichloromethane (CHBrCl2), and 15.6μg L−1 for dibromochloromethane (CHBr2Cl). Bromoform (CHBr3) was not detected. The mean CR for THMs in tap water is 3.96 × 10−4. The results indicate that Fortaleza residents have a higher CR by inhalation than dermal absorption and oral ingestion. The CR for CHCl3 contributes with 68% as compared with the total CR, followed by CHBrCl2 (21%), and CHBr2Cl (11%). The hazard index (HI) is about ten times lower than unity, not indicating non-cancer effects.
  Environmental Monitoring and Assessment 04/2012; 151(1):317-325. · 1.40 Impact Factor
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  Available from: Rommel B. Viana

  Article: First- and second-row transition metal oxa-aza macrocyclic complexes: a DFT study of an octahedral conformation.

  Francisco C A Lima, Rommel B Viana, Thais T da Silva, Solange M S V Wardell, Armando P Nascimento do Filho, José Walkimar M Carneiro, Moacyr Comar, Albérico B F da Silva
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  ABSTRACT: A theoretical study of structures of the 1,7,1 l,17-tetraoxa-2,6,12,16-tetraaza-cycloeicosane ligand ([20]AneN(4)O(4)) coordinated to Fe(2+), Co(2+), Ni(2+), Ru(2+), Rh(2+), and Pd(2+) transition metals ions was carried out with the DFT/B3LYP method. Complexes were fully optimized in C(s) symmetry with the metal ions coordinated either to nitrogen (1a) or oxygen atoms (1b). For all the cases performed in this work, 1a was always more stable than 1b. Considering each row it is possible to see that the binding energy increases with the atomic number. The M(2+) cation binding energies increase in the following order: Fe(2+)<Ru(2+)<Co(2+)<Ni(2+)<Rh(2+)<Pd(2+). In addition, it was observed the preference of Pd(2+) and Rh(2+) complexes for a tetrahedral arrangement, while Fe(2+), Ru(2+), Co(2+), Ni(2+) complexes had a preference for the octahedral arrangement. From the orbital representation results, it was seen that 1b unsymmetrical orbitals may influence the susceptibility over metal ions orientation toward heteroatoms orbitals.
  Journal of Molecular Modeling 01/2012; 18(7):3243-53. · 1.80 Impact Factor
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  Available from: Rommel B. Viana

  Article: Adsorption of sodium dodecyl sulfate on ge substrate: the effect of a low-polarity solvent.

  Rommel B Viana, Albérico B F da Silva, André S Pimentel
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  ABSTRACT: This paper describes the adsorption of sodium dodecyl sulfate (SDS) molecules in a low polar solvent on Ge substrate by using Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy and atomic force microscopy (AFM). The maximum SDS amount adsorbed is (5.0 ± 0.3) × 10(14) molecules cm(-2) in CHCl(3), while with the use of CCl(4) as subphase the ability of SDS adsorbed is 48% lower. AFM images show that depositions are highly disordered over the interface, and it was possible to establish that the size of the SDS deposition is around 30-40 nm over the Ge surface. A complete description of the infrared spectroscopic bands for the head and tail groups in the SDS molecule is also provided.
  International Journal of Molecular Sciences 01/2012; 13(7):7980-7993. · 2.60 Impact Factor
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  Available from: Rommel B. Viana

  Article: Influence of urban activities on polycyclic aromatic hydrocarbons in precipitation: Distribution, sources and depositional flux in a developing metropolis, Fortaleza, Brazil

  Rivelino M. Cavalcante, Francisco W. Sousa, Ronaldo F. Nascimento, Edilberto R. Silveira, Rommel B. Viana
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  ABSTRACT: We measured polycyclic aromatic hydrocarbons (PAHs) in bulk precipitation in the Fortaleza metropolitan area, Ceará, Brazil, for the first time. Because little information is available concerning PAHs in tropical climatic regions, we assessed their spatial distribution and possible sources and the influence of urban activities on the depositional fluxes of PAHs in bulk precipitation. The concentrations of individual and total PAHs (ΣPAHs) in bulk precipitation ranged from undetectable to 133.9 ng.L− 1 and from 202.6 to 674.8 ng.L− 1, respectively. The plume of highest concentrations was most intense in a zone with heavy automobile traffic and favorable topography for the concentration of emitted pollutants. The depositional fluxes of PAHs in bulk precipitation calculated in this study (undetectable to 0.87 μg.m− 2.month− 1) are 4 to 27 times smaller than those reported from tourist sites and industrial and urban areas in the Northern Hemisphere. Diagnostic ratio analyses of PAH samples showed that the major source of emissions is gasoline exhaust, with a small percentage originating from diesel fuel. Contributions from coal and wood combustion were also found. Major economic activities appear to contribute to pollutant emissions.
  Science of The Total Environment 01/2012; 414:287-292. · 3.29 Impact Factor