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ABSTRACT: Textile dyes and dye industrial effluents are widely known for esthetic and toxicity problems. The toxicity of three direct dyes, Direct Blending Rebine (D-BLL), Direct Blending Scarlet (D-GLN), and Direct Blending Yellow (D-3RNL), were examined by the antioxidase and lipid peroxide index. Fish (Carassius auratus) were exposed to 100mg/L test compounds or injected with 200μg/kg corresponding dyes, and then samples of liver were collected at different times (0.5, 1, 3, 5, 7, 10, 13, 17 and 22d ) for analysis of superoxide dismutase (SOD), catalase (CAT), and contents of malondialdehyde (MDA). There is an obvious difference between two poisoning conditions and results indicated injection pattern have a more sensitive response. Besides, SOD, CAT and MDA levels displayed different variation trend following the prolonged duration, implying that dye metabolism generated less toxic or more active substance. The comparison among their intensity of enzyme inhibition showed that the toxicity order is D-BLL>D-GLN>D-3RNL. Additionally, three direct dye molecules were optimized based on the quantum mechanical charge density of a solute molecule interacting with a continuum description of the solvent (SMD) of Self-consistent Reaction Field Theory (SCRF) on B3LYP/LAN2BM level and the stable configurations were obtained. Wiberg bond orders were analyzed and atom in molecule (AIM) 2000 program was employed to estimate the interaction between atoms. The possible degradation pathways and toxicities were speculated based on the computations. The calculation is consistent with the experimental results and analysis.
Ecotoxicology and Environmental Safety 10/2012; · 2.29 Impact Factor
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ABSTRACT: Polyhydroxylated dibenzofuran (PHODF) is an important degradation product of polychlorinated dibenzofuran (PCDF). Four types of hydrogen bonds (the one between a hydroxyl and the oxygen atom in the matrix, between hydroxyls at ortho positions, between the oxygen atom of hydroxyl at position 1 and the hydrogen atom of the matrix at position 9, and between hydroxyls at positions 1 and 9) exist in PHODFs. The energies of the hydrogen bonds were ascertained by comparing the two configurational isomers as approximately 8-11kJmol(-1), 16-21kJmol(-1), 5-8kJmol(-1) and 23-25kJmol(-1), respectively. An experiment was designed to verify the bond energies, and the entrance geometry on main paths was studied by AIM 2000 program. The most stable in each group of configurational isomers was ascertained on the basis of evaluating the effect of hydrogen bonds. Their thermodynamic properties (standard state entropy S°, standard enthalpy Δ(f)H° and standard Gibbs energy of formation Δ(f)G°) were calculated from the combination of density functional theory (DFT) at B3LYP/6-311G** level and isodesmic reactions. Octanol/water partition coefficients (logK(ow)) were calculated on line with molinspiration methodology based on group contributions. The number and position of hydroxyl substitution (N(PHOS)) can be a good indicator of these properties for all stable PHODF congeners. The configurations most likely to form are those with a hydrogen bond (Type IV). How intramolecular hydrogen bond influences ionization was also investigated and the first-order ionization constant for each stable conformation was obtained with the self-consistent reaction field (SCRF) method.
Journal of molecular graphics & modelling 06/2012; 38C:396-410. · 2.17 Impact Factor
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ABSTRACT: Polyhydroxylated dibenzo-p-dioxins (PHODDs) are important metabolic and synthetic products of polychlorinated dibenzo-p-dioxins (PCDDs). Two types of hydrogen bonds exist in PHODD molecules: one between a hydroxyl group (HO) and an oxygen atom of the ether bond, and the other between two ortho hydroxyls of a benzene ring. By fully optimized calculation with density functional theory (DFT), their bond energies were ascertained to be approximately 9-14 kJ/mol and 15-19 kJ/mol respectively by the comparison of standard Gibbs energy of formation (Δ(f)G(θ)) between different molecules, which was experimentally verified. The two types of hydrogen bonds affect the hydrophilicity and stability of the molecules. The torsional potential of hydroxyls and the orientation making the congener most stable were obtained. The octanol-water partition coefficients (logK(ow)s) were calculated based on the group contribution method, and the standard state entropy (S(θ)), standard enthalpy (Δ(f)H(θ)) of formation and Δ(f)G(θ) were obtained from the combination of DFT calculation and isodesmic reaction for the stable PHODD congeners. The number and position of hydroxyl substitution (N(PHOS)) were employed as descriptors to establish quantitative structure-property relationship (QSPR) models. Although the hydrophilicity of PHODDs increases with the number of hydroxyl groups, it is impaired by the intramolecular hydrogen bonds. The logK(ow)s of PHODDs are much smaller than those of PCDDs, and the variation trend with the number of substituents is different. In addition, the relative stability order of PHODD congeners was theoretically proposed, which is quite different from that of PCDDs. Considering the ionization in water, first-order ionization constants of PHODDs were calculated according to the results of SMD method of Self-Consistent Reaction Field Theory (SCRF), and they were influenced by the hydrogen bonds.
Science of The Total Environment 11/2011; 414:404-16. · 3.29 Impact Factor
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ABSTRACT: We investigated the heat of formation (ΔfH) of polynitrocubanes using density functional theory B3LYP and HF methods with 6-31G*, 6-311+G**, and cc-pVDZ basis sets. The results indicate that ΔfH firstly decreases (nitro number m=0–2) and then increases (m=4–8) with each additional nitro group being introduced to the cubane skeleton. ΔfH of octanitrocubane is predicted to be 808.08 kJ mol−1 at the B3LYP/6-311+G** level. The Gibbs free energy of formation (ΔfG) increases by about 40–60 kJ mol−1 with each nitro group being added to the cubane when the substituent number is fewer than 4, then ΔfG increases by about 100–110 kJ mol−1 with each additional group being attached to the cubic skeleton. Both the detonation velocity and the pressure for polynitrocubanes increase as the number of substituents increases. Detonation velocity and pressure of octanitrocubane are substantially larger than the famous widely used explosive cyclotetramethylenetetranitramine (HMX).
Propellants Explosives Pyrotechnics 04/2009; 34(2):106 - 109. · 1.10 Impact Factor
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ABSTRACT: The density functional theory (DFT) BLYP and B3LYP method with 3–21G* and 6–31G** basis sets were used to predict the structures, natural bond orbital (NBO) atomic charges, and ring interactions of 2,4,6-tris(3′,5′-diamino-2′,4′,6′-trinitrophenylamino)-1,3,5-triazine (PL-1). Approximately, the molecule possesses C3 symmetry with three benzene rings tilted to the triazine plane. The interactions among three 3′,5′-diamino-2′,4′,6′-trinitrophenylamino groups are of additivity. The heat of formation of PL-1 was estimated to be 427.6 J/mol via isodesmic reaction. Detonation velocity and pressure are 8.5 km/s and 35.5 GPa, respectively.
Journal of Energetic Materials. 01/2009; 27(1):51-62.
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ABSTRACT: The molecular geometries of 209 polybrominated diphenyl ethers (PBDEs) were optimized at the B3LYP/6-31G level with Gaussian 98 program. The calculated structural parameters were taken as theoretical descriptors to establish two novel QSPR models for predicting supercooled liquid vapor pressures (P(L)) and octanol/air partition coefficients (K(OA)) of PBDEs based on the theoretical linear solvation energy relationship (TLSER) model, respectively. The two models achieved in this work both contain three variables: most negative atomic partial charge in molecule (q(-)), dipole moment of the molecules (mu) and mean molecular polarizability (alpha), of which R(2) values are both as high as 0.997, their root-mean-square errors in modeling (RSMEE) are 0.069 and 0.062 respectively. In addition, the F-value of two models are both evidently larger than critical values F(0.05) and the variation inflation factors (VIF) of variables herein are all less than 5.0, suggesting obvious statistic significance of the P(L) and K(OA) predicting models. The results of Leave-One-Out (LOO) cross-validation for training set and validation with external test set both show that the two models obtained exhibited optimum stability and good predictive power. We suggest that the QSPRs derived here can be used to predict accurately P(L) and K(OA) for non-tested PBDE congeners from Mono-BDEs to Hepta-BDEs and from Mono-BDEs to Hexa-BDEs, respectively.
Science of The Total Environment 02/2008; 389(2-3):296-305. · 3.29 Impact Factor
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ABSTRACT: The number of Cl substitution positions (N(PCS)) of all 209 possible molecular structure patterns of polychlorinated diphenyl ethers (PCDEs) were correlated with their partition properties n-octanol/water partition coefficient (lgK(ow)) and sub-cooled liquid water solubilities (-lgS(w,l)). The correlation coefficients (R) and the leave-one-out (LOO) cross-validation correlation coefficients (R(cv)) of all the 6-descriptor models for lgK(ow) and -lgS(w,l) are more than 0.98. By using stepwise multiple regression (SMR), the best two models of lgK(ow) with three descriptors (R=0.9,913) and lgS(w,l) with four descriptors(R=0.9,818) were obtained respectively. Based on these equations, the two properties of all 209 PCDEs were predicted. Model validation showed that the two models exhibit optimum stability and high predictive power. Moreover, results of prediction were further compared with data from similar studies by molecular connectivity indices (MCIs) and PM3 methods.
Science of The Total Environment 09/2007; 382(1):59-69. · 3.29 Impact Factor
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ABSTRACT: Optimized calculation of 135 Polychlorinated Dibenzothiophenes (PCDTs) was carried out at B3LYP/6-31G* level with Gaussian 98 program. The structural and thermodynamic parameters identified with the Theoretical Linear Solvation Energy Relationship (TLSER) model were employed as theoretical descriptors in the Quantitative Structure–Retention Relationship (QSRR) models derived to predict Retention Indices (RI) of PCDTs. Two QSRR models developed for RI of PCDTs contain only one variable: the mean molecular polarizability (α) and entropy (S⊖), respectively. The best fitted equation for the correlation between RI and α of 25 PCDTs with experimental data was RI=−126.52(±2.86)+0.97(±0.01)α with R2 as 0.9942, SD as 2.22, suggesting high accuracy of the RI predicting model. The correlation between RI and S⊖ is strong, and the equation was RI=−184.17 (±3.09)+0.48(±0.01)S⊖ with R2 as 0.9961, SD as 1.81. Furthermore, using position of Cl substitution (NPCS) method, QSRR model of PCDTs was obtained: RI=6.23(±0.75)+13.36(±0.19)N with R2 as 0.9953, SD as 1.99. Method validation also showed that the three models of this study exhibit optimum stability. Finally, RI values of 110 PCDT congeners without experimental value were also predicted with the three models, respectively.
QSAR & Combinatorial Science 03/2007; 26(8):889 - 896. · 1.55 Impact Factor
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ABSTRACT: Optimized calculation of 75 Polychlorinated Dibenzo-p-dioxins (PCDDs) and their parent compound DD was carried out at B3LYP/6-31G* level with GAUSSIAN 98 program. The structural parameters identified with the Theoretical Linear Solvation Energy Relationship (TLSER) model were employed as theoretical descriptors in the Quantitative Structure–Property Relationship (QSPR) models derived to predict the aqueous solubility (−lgSw) and n-octanol/water partition coefficients (lgKow) of PCDDs. The regression model obtained to predict −lgSw contains only one variable: the mean molecular polarizability (α). The best fitted equation for the correlation between −lgSw and α of 12 PCDDs was −lgSw=−3.6425+0.0693α with r2 as 0.9776, Standard Deviation (SD) as 0.30, and suggesting high accuracy of the −lgSw predicting model. At the same time, there exists high correlation (r2=0.8862) between n-octanol/water partition coefficients (lgKow) and the mean molecular polarizability (α), and the SD is small. The mean molecular polarizability (α) is the only theoretical descriptor used in the QSPR model derived to predict lgKow.
QSAR & Combinatorial Science 10/2006; 26(3):352 - 357. · 1.55 Impact Factor
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ABSTRACT: Optimized calculation of 209 PCBs was carried out at B3LYP/6-31G* level in Gaussian98 program to obtain their structural parameters. It was found there is significant correlation between the Cl substitution position and some structural parameters such as α (r2=0.9972), EHOMO (r2=0.8874) etc. Consequently the numbers of Cl substitution positions (N) were taken as theoretical descriptors to establish the novel QSPR model for predicting n-octanol/water partition coefficients (logKow) of all PCB congeners, which can be used directly without computation of their complex structural and thermodynamic parameters. The new model achieved in this work contains three variables, of which r2=0.9497 and q2=0.9465. In addition, the variation inflation factors (VIF) of variables in the present model are all less than 5.0, suggesting high accuracy of the logKow predicting model. And the results of cross-validation test and method validation (r2=0.9640 and q2=0.9606) also showed the models of this study exhibited optimum stability, convenience for use and better predictive power than that from AM1 method.
QSAR & Combinatorial Science 02/2006; 25(4):333 - 341. · 1.55 Impact Factor
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ABSTRACT: Three quantitative structure-retention relationship (QSRR) models have been developed for gas chromatographic relative retention indices (RIs) of polychlorinated naphthalene (PCN) congeners. With computation at HF/6-31G* and B3LYP/6-31G* levels in Gaussian98 program, the structural parameters of PCNs were obtained and used as chemical descriptors to correlate with their gas chromatographic RIs by multiple linear regression analysis, resulting in model 1 and model 2. The squared correlation coefficients (r2) of the first two models are 0.9814 and 0.9957, and the cross-validation correlation coefficients (q2) are 0.9771 and 0.9948, respectively. On the other hand, the third model, model 3, was developed using the relative position of chlorine substitution as molecular descriptor, and its multiple squared correlation coefficient is r2 = 0.9967 and q2 = 0.9959, suggesting model 3 is practical and especially has a optimum predictive power.
QSAR & Combinatorial Science 10/2005; 25(1):7 - 14. · 1.55 Impact Factor
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ABSTRACT: Based on MLSER model and quantum chemical descriptors computed at HF/STO-3G, HF/LANL2DZ, B3LYP/LANL2D and B3LYP/6-31G* levels, different quantitative structure-activity relationships (QSARs) to the toxicity -logEC50 and -logLC50 of 28 alkyl(1-phenylsulfonyl) cycloalkane-carboxylates were obtained. It is suggested that the eight models developed in the present study all have good correlation and relatively small error, in which the two models with three variables, polarizability, EHOMO and limit charge density from B3LYP/6-31G* level, exhibited the best optimal correlation (r2=0.9455, 0.9411; and q2=0.9289, 0.9162, respectively) and smallest error, and thus are advantageous to other models. It was also found that polarizability is the most significant factor influencing toxicity. The toxicity increased with increasing polarizability, while decreased with increasing dipole moment and decreasing of EHOMO.
QSAR & Combinatorial Science 01/2005; 24(2):211 - 217. · 1.55 Impact Factor
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Zun Yao Wang
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ABSTRACT: The reaction space map (RESMAP) representation is proposed for the comprehensive description of the chlorination and dechlorination reactions of polychlorobenzenes. By using the B3LYP/6-311G** energies and by assuming the chemical reactions which govern the chlorination and dechlorination processes of polychlorobenzenes, the relative energies of polychlorobenzenes and polychlorophenyl radicals were defined artificially. They were collected as the RESMAP which has the relative energies of polychlorobenzenes at the diagonal parts and the polychlorophenyl radicals connecting two polychlorobenzenes at the off-diagonal parts. The RESMAPs created for three models for the chlorination/dechlorination processes provided a general view of the thermodynamically controlled isomer distributions and chlorination/dechlorination reaction patterns for benzene and (poly)chlorinated benzenes.
02/2002;
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ABSTRACT: The fully optimized calculation of dibenzo-p-dioxin (DD) and 75 polychlorinated dibenzo-dioxins (PCDDs) were carried out at the B3LYP/6-311G** level. The corresponding total energy, enthalpy, entropy and free energy were calculated. In addition, the dependences of the calculated parameters on the number and the position of chlorine substitute were discussed. By designing isodemic reactions, standard formation heat and free energy were obtained, from which the order of relative stability for PCDDs was determined. Based on the comparison of the stability order with the observed percentage of PCDDs from incinerator, a predominant thermodynamic control process for formation of tetrachlorinated dibenzo-dioxins (TCDDs), pentachlorinated dibenzo-dioxins (Penta-CDDs) and hexachlorinated dibenzo-dioxins (Hexa-CDDs) in incineration was suggested.
Journal of Molecular Structure THEOCHEM 672:97-104. · 1.44 Impact Factor
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ABSTRACT: The reaction space map (RESMAP) representation is proposed for the comprehensive description of the chlorination and dechlorination reactions of polychlorobenzenes. By using the B3LYP/6-311G energies and by assuming the chemical reactions which govern the chlorination and dechlorination processes of polychlorobenzenes, the relative energies of polychlorobenzenes and polychlorophenyl radicals were defined artificially. They were collected as the RESMAP which has the relative energies of polychlorobenzenes at the diagonal parts and the polychlorophenyl radicals connecting two polychlorobenzenes at the off-diagonal parts. The RESMAPs created for three models for the chlorination/dechlorination processes provided a general view of the thermodynamically controlled isomer distributions and chlorination/dechlorination reaction patterns for benzene and (poly)chlorinated benzenes.
Journal of Chemical Information and Computer Sciences 42(2):284-9.
