Conformational analysis of phosphorus polymers with flame retardant property

The phosphorous, halogen and nitrogen-containing polymers have excellent thermal stability and good flame retardant properties. In this paper the monomer structure of 4-(l, 1,1,3,3,3- hexafluoro-2 -phenylpropan-2 -yl)phenyl diphenyl phosphate was simulated by molecular mechanics calculations using the MMFF94s force field included in the Omega software. The conformations thus obtained were further minimized by the semiempirical RM1 method included in the MOP AC 2009 software The Omega conformation of minimum energy was energy optimized by the Hartree-Fock Self-Consistend Field (RHF) method, in order to obtain a stable structure. Structural compound features which characterize the most stable energetically conformations obtained by molecular mechanics and quantum chemical methods were compared with experimental data, yielding a unified structure

An assessment of heavy metals contamination of soils and vegetation near an agrotechnical farm from area Timis

The objective of the study was the determination of the trace metal (Fe, Cr, Zn, Pb) status of soils and vegetables in the vicinity of a livestock (cattle, piggery, sheep and goat and poultry sections) using atomic absorption, spectrophotometry. Vegetable samples taken within the vicinity showed 0.85-0.190 mgkg A Fe, 0.356-0.549 mgkg' 1 Zn,0.005-0.432 mgkg' 1 Cr and 0.017-0.029 mgkg' 1 Pb. Analytical results indicated that soils and vegetables values were below the WHO critical toxic levels. Statistically, there were significant correlations between trace metals concentrations of the test and control samples. The levels of trace metals were not considered to be toxic for human and animal uses

Conformational analysis of bicyclic phosphate derivatives by computational methods

Trimethylolpropane phosphate is an ethyl bicyclophosphate produced during the partial pyrolysis of certain synthetic, ester-based turbine lubricants supplemented with phosphatebased lubricity additives, being considered as having high toxicity. In this paper its structure was simulated by molecular mechanics methods using the OPLS, AMBER and MMFF94s force fields by the AMI semiempirical approach and the Hartree-Fock Self-Consistend Field (RHF) method and results were compared with X-ray structure. Generally the generated structures obtained by these methods reproduced with accuracy the experimental data. The structure obtained by the RFIF approach was closer to experimental data

UV/VIS spectral simulation of a symmetrical disazo direct dye by the Hartree-Fock approximation

A disazo direct dye having a symmetrical structure, derived from the 4,4'-diaminostilbene-2,2'- disulfonic acid was previously synthesized and applied to water-based acrylic resins, in coatings. The dye structure was previously experimentally analyzed using the UV/VIS spectroscopy and theoretical Density Functional Theory (DFT) calculations were employed to compare the calculated with the experimental UV/VIS wavelengths. In this paper the molecular dye structure was modeled using the MMFF94 force field and the Hartree-Fock (HF) approach. The UV/VIS spectrum of the minimum energy optimized structure was simulated using the Configuration Interaction Singles (CIS), the Time-Dependent (TD) and the Zerner's Intermediate Neglect of Differential Overlap (ZINDO) methods to evaluate the electronic excitation spectra. The ZINDO approach gave better maximum absorption calculated values compared to the CIS and TD methods, as previously noticed in case of using the DFT approach. A generally good agreement between the experimental and theoretical computed absorption maxima was noticed