The Experts below are selected from a list of 90 Experts worldwide ranked by ideXlab platform
Eduardo A Castro - One of the best experts on this subject based on the ideXlab platform.
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Study of the Topological Properties of Some Pseudohalides.
Journal of chemical theory and computation, 2006Co-Authors: N. B. Okulik, A H Jubert, Eduardo A CastroAbstract:The pseudohalide principle has been used extensively in nonmetal chemistry to predict the structure and stability of many molecular species. The 1,2,3,4-thiatriazole-5-thiolate anion, CS2N3(-), is of particular interest. In a short communication we have recently reported the topological study of some CS2N3(-)containing species reported by Crawford et al. Previous reports on these compounds showed that in covalent derivatives not only does the ring remain intact but also the site of attachment of the R group is most likely at the exocyclic sulfur atom in contrast to the previously suggested N-R connectivity. Therefore, the structure and bonding of derivatives of the CS2N3(-) moiety is clearly an important question. With that in our mind, we undertook a topological analysis, based on the AIM theory, to gain more insight into the bonding in covalent derivatives of the CS2N3(-) moiety, trying to find an explanation to the origin of the N-H and S-H connectivities. The question is which is the reason that makes all the covalent derivatives prefer the S-R connectivity while the Hydracid has an N-H one.
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Bonding in some covalent derivatives of the 1,2,3,4-thiatriazole-5-thiolate anion. A topological study
Journal of Molecular Structure-theochem, 2006Co-Authors: N. B. Okulik, A H Jubert, Eduardo A CastroAbstract:Abstract The study of pseudohalides has found a deep interest to nonmetal chemists for many years. Due to the similarities between the halides and the pseudohalides, the pseudohalide family of compounds is of fundamental chemical interest. The pseudohalide concept was introduced in 1925 and since its introduction, the pseudohalide principle has been used extensively in nonmetal chemistry to predict the structure and stability of many molecular species. The so-called ‘azidodithiocarbonate’ anion, more properly referred to as the 1,2,3,4-thiatriazole-5-thiolate anion, CS2N3-, is of particular interest. In a short communication we have recently reported the topological study of some CS2N3-containing species reported by Crawford et al. Previous reports on these compounds showed that in covalent derivatives, not only does the ring remain intact but also the site of attachment of the R group is most likely at the exocyclic sulfur atom in contrast to the previously suggested N-R connectivity. Therefore, the structure and bonding of derivatives of the CS2N3- moiety is clearly an important question. With that in our mind, we undertook a topological analysis, based on the AIM theory, to gain more insight into the bonding in covalent derivatives of CS2N3- moiety, trying to find an explanation to the origin of the NH and S-H connectivities. The question is: which is the reason that makes all the covalent derivatives prefer the S-R connectivity while the Hydracid has an N-H one?
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theoretical study of new pseudohalogen cs2n3 and some related compounds
Journal of Molecular Structure-theochem, 2002Co-Authors: N. B. Okulik, A H Jubert, Eduardo A CastroAbstract:Abstract We have performed a detailed theoretical study of four structures: (i) pseudohalide anion [CS 2 N 3 ] − ( 1 ) in the salt [Na + ][CS 2 N 3 ] − 4H 2 O, (ii) the Hydracid HN 3 SCS ( 2 ), (iii) the interpseudohalogen CS 2 N 3 –CN ( 3 ) and the dipseudohalogen (CS 2 N 3 ) 2 ( 4 ), formally deriving from the radical CS 2 N 3 . The corresponding topological characterization was made by means of an analysis of the electronic charge resorting to the AIM topological theory. We have found satisfactory agreement among the geometrical parameters predicted by the theoretical methods and the experimental parameters available in the standard literature. The analysis of the topological properties calculated at the bond critical points allowed us to describe the chemical bonds in every structure as having a covalent nature, to assign a polar character to the exocyclic C–S and the delocalization of the electronic density over the ring surfaces.
B. Laroui - One of the best experts on this subject based on the ideXlab platform.
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Infrared profile of van der Waals dimers HCl-RG* (RG*=Ar, Kr, Xe) trapped in rare gas matrices
The Journal of Chemical Physics, 1992Co-Authors: C. Girardet, A. Lakhlifi, B. LarouiAbstract:The infrared profile of the van der Waals dimers HCl–RG* trapped in a ternary matrix containing small molar ratio of Hydracids (≤1/1000) and of rare gas dopants (≂1/10) is theoretically investigated. The homogeneous profile of a single dimer is determined, using a conventional cumulant expansion of the coupling Hamiltonian between a renormalized optical system described by the vibration‐orientation Hamiltonian of the trapped molecule and a renormalized bath defined by the lattice modes and the molecule and dopant center of mass motions. The influence of the ternary matrix inhomogeneities is also studied within the framework of a stochastic model which describes the interaction between the various species in the solid. A detailed analysis of the homogeneous and inhomogeneous broadenings of the infrared lines of these dimers is done on the basis of relatively accurate interaction potentials, previously determined. The comparison of the infrared profiles with recent FTIRspectroscopic data shows a fair agreement in most cases.
Taishung Chung - One of the best experts on this subject based on the ideXlab platform.
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conceptual demonstration of novel closed loop pressure retarded osmosis process for sustainable osmotic energy generation
Applied Energy, 2014Co-Authors: Gang Han, Taishung ChungAbstract:For the first time, one novel closed-loop pressure retarded osmosis (PRO) process promoted by an effective hydroacid complex draw solution has been demonstrated for harvesting the renewable salinity-gradient energy. The complex draw solute was molecularly constructed to possess unique characteristics of high osmotic pressure, large molecular size and relative low viscosity, and easy regeneration. Compared to conventional PRO processes, the newly developed closed-loop PRO process exhibits promising advantages of sustainable high power output, negligible internal concentration polarization and low membrane fouling, as well as no problems of feed water pretreatment and brackish water discharge. Employing a highly permeable (A=4.30 LMH/bar) and selective (B=0.47 LMH) thin film composite PRO hollow fiber membrane, a power density of 16.2W/m2 can be achieved with an ultralow reverse solute flux (Js/Jw<0.062gL−1) at 12bar when using 1M complex draw solution and deionized water as feeds. The diluted complex draw solution can be regenerated via a solvent precipitation process, and the outstanding PRO performance could be almost fully recovered. We believe the newly developed closed-loop PRO process shows great potential for salinity-gradient energy capture, although the specific benefits have to be fully defined through energy or cost analysis.
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novel forward osmosis process to effectively remove heavy metal ions
Journal of Membrane Science, 2014Co-Authors: Qingchun Ge, Taishung ChungAbstract:Abstract In this study, a novel forward osmosis (FO) process for the removal of heavy metal ions from wastewater was demonstrated for the first time. The proposed FO process consists of a thin-film composite (TFC) FO membrane made from interfacial polymerization on a macrovoid-free polyimide support and a novel bulky hydroacid complex Na 4 [Co(C 6 H 4 O 7 ) 2 ]·2H 2 O (Na–Co–CA) as the draw solute to minimize the reverse solute flux. The removal of six heavy metal solutions, i.e., Na 2 Cr 2 O 7 , Na 2 HAsO 4 , Pb(NO 3 ) 2 , CdCl 2 , CuSO 4 , Hg(NO 3 ) 2 , were successfully demonstrated. Water fluxes around 11 L/m 2 /h (LMH) were harvested with heavy metals rejections of more than 99.5% when employing 1 M Na–Co–CA as the draw solution to process 2000 ppm(1 ppm=1 mg/L) heavy metal solutions at room temperature. This FO performance outperforms most nanofiltration (NF) processes. In addition, the high rejections were maintained at 99.5% when a more concentrated draw solution (1.5 M) or feed solution (5000 ppm) was utilized. Furthermore, rejections greater than 99.7% were still achieved with an enhanced water flux of 16.5 LMH by operating the FO process at 60 °C. The impressive heavy metal rejections and satisfactory water flux under various conditions suggest great potential of the newly developed FO system for the treatment of heavy metal wastewater.
N. B. Okulik - One of the best experts on this subject based on the ideXlab platform.
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Study of the Topological Properties of Some Pseudohalides.
Journal of chemical theory and computation, 2006Co-Authors: N. B. Okulik, A H Jubert, Eduardo A CastroAbstract:The pseudohalide principle has been used extensively in nonmetal chemistry to predict the structure and stability of many molecular species. The 1,2,3,4-thiatriazole-5-thiolate anion, CS2N3(-), is of particular interest. In a short communication we have recently reported the topological study of some CS2N3(-)containing species reported by Crawford et al. Previous reports on these compounds showed that in covalent derivatives not only does the ring remain intact but also the site of attachment of the R group is most likely at the exocyclic sulfur atom in contrast to the previously suggested N-R connectivity. Therefore, the structure and bonding of derivatives of the CS2N3(-) moiety is clearly an important question. With that in our mind, we undertook a topological analysis, based on the AIM theory, to gain more insight into the bonding in covalent derivatives of the CS2N3(-) moiety, trying to find an explanation to the origin of the N-H and S-H connectivities. The question is which is the reason that makes all the covalent derivatives prefer the S-R connectivity while the Hydracid has an N-H one.
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Bonding in some covalent derivatives of the 1,2,3,4-thiatriazole-5-thiolate anion. A topological study
Journal of Molecular Structure-theochem, 2006Co-Authors: N. B. Okulik, A H Jubert, Eduardo A CastroAbstract:Abstract The study of pseudohalides has found a deep interest to nonmetal chemists for many years. Due to the similarities between the halides and the pseudohalides, the pseudohalide family of compounds is of fundamental chemical interest. The pseudohalide concept was introduced in 1925 and since its introduction, the pseudohalide principle has been used extensively in nonmetal chemistry to predict the structure and stability of many molecular species. The so-called ‘azidodithiocarbonate’ anion, more properly referred to as the 1,2,3,4-thiatriazole-5-thiolate anion, CS2N3-, is of particular interest. In a short communication we have recently reported the topological study of some CS2N3-containing species reported by Crawford et al. Previous reports on these compounds showed that in covalent derivatives, not only does the ring remain intact but also the site of attachment of the R group is most likely at the exocyclic sulfur atom in contrast to the previously suggested N-R connectivity. Therefore, the structure and bonding of derivatives of the CS2N3- moiety is clearly an important question. With that in our mind, we undertook a topological analysis, based on the AIM theory, to gain more insight into the bonding in covalent derivatives of CS2N3- moiety, trying to find an explanation to the origin of the NH and S-H connectivities. The question is: which is the reason that makes all the covalent derivatives prefer the S-R connectivity while the Hydracid has an N-H one?
-
theoretical study of new pseudohalogen cs2n3 and some related compounds
Journal of Molecular Structure-theochem, 2002Co-Authors: N. B. Okulik, A H Jubert, Eduardo A CastroAbstract:Abstract We have performed a detailed theoretical study of four structures: (i) pseudohalide anion [CS 2 N 3 ] − ( 1 ) in the salt [Na + ][CS 2 N 3 ] − 4H 2 O, (ii) the Hydracid HN 3 SCS ( 2 ), (iii) the interpseudohalogen CS 2 N 3 –CN ( 3 ) and the dipseudohalogen (CS 2 N 3 ) 2 ( 4 ), formally deriving from the radical CS 2 N 3 . The corresponding topological characterization was made by means of an analysis of the electronic charge resorting to the AIM topological theory. We have found satisfactory agreement among the geometrical parameters predicted by the theoretical methods and the experimental parameters available in the standard literature. The analysis of the topological properties calculated at the bond critical points allowed us to describe the chemical bonds in every structure as having a covalent nature, to assign a polar character to the exocyclic C–S and the delocalization of the electronic density over the ring surfaces.
C. Girardet - One of the best experts on this subject based on the ideXlab platform.
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Infrared profile of van der Waals dimers HCl-RG* (RG*=Ar, Kr, Xe) trapped in rare gas matrices
The Journal of Chemical Physics, 1992Co-Authors: C. Girardet, A. Lakhlifi, B. LarouiAbstract:The infrared profile of the van der Waals dimers HCl–RG* trapped in a ternary matrix containing small molar ratio of Hydracids (≤1/1000) and of rare gas dopants (≂1/10) is theoretically investigated. The homogeneous profile of a single dimer is determined, using a conventional cumulant expansion of the coupling Hamiltonian between a renormalized optical system described by the vibration‐orientation Hamiltonian of the trapped molecule and a renormalized bath defined by the lattice modes and the molecule and dopant center of mass motions. The influence of the ternary matrix inhomogeneities is also studied within the framework of a stochastic model which describes the interaction between the various species in the solid. A detailed analysis of the homogeneous and inhomogeneous broadenings of the infrared lines of these dimers is done on the basis of relatively accurate interaction potentials, previously determined. The comparison of the infrared profiles with recent FTIRspectroscopic data shows a fair agreement in most cases.
