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5,7-Bis(benz-yloxy)-2-phenyl-4H-chromen-4-one
(International Union of Crystallography, 2008-11-29) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Jaswant, Buckle; Sulochana, Nagarajan
In the title compound, C29H22O4, the chromene ring is almost planar with a small puckering [0.143 (2) Å]. The crystal structure is stabilized by C - H⋯O and C - H⋯π inter-actions. Edge-to-face (centroid-centroid distances of 3.894 and 3.673 Å) and face-to-face (centroid-centroid distance of 3.460 Å) π-π-ring electron inter-actions are also observed. © 2008.
2-Phenyl-5,7-bis(prop-2-en-1-yloxy)-4H-chromen-4-one
(International Union of Crystallography, 2008-12-03) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, Nagarajan
In the title compound, C21H18O4, tthe dihedral angle between the chromene ring system and the pendant phenyl ring is 6.1 (1)°. The crystal structure is stabilized by an intermolecular C - H⋯O and C - H⋯π inter-actions.
Dimethyl 2,2′-[(4-oxo-2-phenyl-4H-chromene-5,7-diyl)dioxy]diacetate: A more densely packed polymorph
(International Union of Crystallography, 2009-01-14) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Jaswant, Buckle; Sulochana, Nagarajan
The title mol-ecule, C21H18O8, crystallizes in two crystal polymorphs, see also Nallasivam, Nethaji, Vembu & Jaswant [Acta Cryst. (2009), E65, o314-o315]. The mol-ecules of both polymorphs differ by the conformation of the oxomethyl-acetate groups. The title mol-ecules are rather planar compared to the mol-ecules of the other polymorph. In the title mol-ecule, one of the oxomethyl-acetate groups is disordered (occupancies of 0.6058/0.3942). The structures of both polymorphs are stabilized by C - H⋯O and C - H⋯π inter-actions. Due to the planarity of the title mol-ecules and similar inter-molecular inter-actions, the title mol-ecules are more densely packed than those of the other polymorph.
5,7-Dimeth-oxy-2-phenyl-4H-chromen-4-one
(International Union of Crystallography, 2009-02-11) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, Nagarajan
The asymmetric unit of the title compound, C17H 14O4, contains two independent mol-ecules which differ in the relative orientations of the phenyl rings with repect to the essentially planar [maximum deviations of 0.029 (2) and 0.050 (2) Å in the two mol-ecules] chromene fused-ring system, forming dihedral angles of 10.3 (5) and 30.86 (5)° in the two mol-ecules. The crystal structure is stabilized by weak C - H⋯O and C - -H⋯π inter-actions, and π-π stacking inter-actions.
6,8-Dibromo-5-hydr-oxy-4-oxo-2-phenyl-4H-chromen-7-yl acetate
(International Union of Crystallography, 2009-02-21) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, Nagarajan
In the title compound, C17H10Br2O5, the chromene ring is almost planar with minimal puckering [total puckering amplitude = 0.067 (4) Å]. The dihedral angle between chromeme ring system and phenyl ring is 3.7 (2)°. The crystal structure is stabilized by intermolecular C - H⋯O inter-actions and an intramolecular O - H⋯O hydrogen bond also occurs.
1-Benzoyl-3,3-bis(propan-2-yl)thiourea
(International Union of Crystallography, 2010-07-24) Gunasekaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
Two independent thiourea derivatives comprise the asymmetric unit of the title compound, C14H20N2OS. The major difference between the mol-ecules relates to a twist in the relative orientation of the benzene rings [torsion angles = 4.5 (2) and -19.9 (2)° for the two independent mol-ecules]. The thio-carbonyl and carbonyl groups lie to opposite sides of the mol-ecule as there are twists about the central N - S bond [torsion angles = 83.90 (15) and 81.77 (15)°]. Supra-molecular chains extending parallel to [101] with a stepped topology and mediated by N - H⋯O hydrogen bonding feature in the crystal structure. C - H⋯O and C - H⋯π inter-actions are also present.
3-Benzoyl-1,1-dibenzylthiourea
(International Union of Crystallography, 2010-09-18) Gunasekaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
Two independent thio-urea molecules comprise the asymmetric unit of the title compound, C22H20N2OS. The central N-C(=S)N(H)C(=O) atoms in each molecule are virtually superimposable and each is twisted [C - N - C - S torsion angles = 121.3 (3) and -62.3 (4)°]. The molecules differ only in terms of the relative orientations of the benzyl benzene rings [major difference between the C - N - C - C torsion angles of -146.6 (3) and -132.9 (3)°]. The presence of N - H⋯S hydrogen bonding leads to the formation of supra-molecular chains along the a axis. These are consolidated in the crystal packing by C - H⋯O interactions. The crystal was found to be a combined non-merohedral and racemic twin (twin law 1̄00/01̄0/001), with the fractional contribution of the minor components being approximately 9 and 28%.
1-Benzoyl-3,3-dibutylthiourea
(International Union of Crystallography, 2010-09-25) Gunasekaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
The title molecule, C16H24N2OS, is twisted about the central N(H) - C bond with a C - N(H) - C - N torsion angle of -62.67 (15)°. The carbonyl group is twisted out of the plane of the benzene ring, forming a C - C - C=O torsion angle of -25.06 (17)°. In the crystal, molecules related by centres of symmetry are linked by pairs of inter-molecular N - H⋯S hydrogen bonds, forming eight-membered {⋯HNCS}2 synthons. These are further connected by weak via C - H⋯O contacts, forming a two-dimensional array in the bc plane.
1-Benzoyl-3,3-bis-(2-methylpropyl)thiourea
(International Union of Crystallography, 2011-02-12) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R.T.
The title compound, C16H24N2OS, is twisted about the central N(H) - C bond with the C - N - C - S torsion angle being 119.6 (3)°. The carbonyl O and thione S atoms are directed to opposite sides of the molecule, a conformation that allows for the formation of a linear supramolecular chain comprising alternating eight-membered {⋯HNCS} 2 and 14-membered {⋯HCNCNCO}2 synthons.
{4-Bromo-2-[(2-sulfidophenyl)iminomethyl]phenolato-k3 S,N,O}(triphenylphosphane-kP)nickel(II)
(International Union of Crystallography, 2011-03-12) Muthu Tamizh, M.; Karvembu, R; Varghese, B; Tiekink, Edward R. T.
The NiII atom in the title complex, [Ni(C13H 8BrNOS)(C18H15P)], is coordinated by the N, O and S atoms of he dianionic tridentate ligand, and its square-planar geometry is completed by a phosphane P atom. The dihedral angle between the aromatic rings in the 4-bromo-2-[(2-sulfidohenyl)imino-meth-yl]phenolate ligand is 2.01 (14)°. The most prominent feature of the packing is the presence of supramolecular chains aligned along the a axis, mediated by C - H⋯S interactions.
1-Benzoyl-3-methyl-3-pentylthiourea
(International Union of Crystallography, 2011-04-16) Gunasekaran, N; Jerome, P; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
Two independent molecules comprise the asymmetric unit of the title compound, C14H20N2OS. These differ in the relative orientations of the pentyl chains [C-C-C-C torsion angles = 176.7 (3) and 176.4 (3)°]. Significant twists are evident in each molecule, the dihedral angles formed between the thiourea and amide residues being 53.47 (17) and 55.81 (17)°. In the crystal, each molecule self-associates via a centrosymmetric eight-membered {⋯HNC S}2 synthon, and these are connected into a supramolecular chain along [110] via C-H⋯O contacts. Disorder is noted for one of the independent molecules in that two orientations (50:50) were resolved for its benzene ring.
Bis(3-benzoyl-1,1-disecbutyl-thioureato- 2 O,S)palladium(II)
(International Union of Crystallography, 2011-09-17) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
The complex molecule of the title complex, [Pd(C 16H 23N 2OS) 2], is completed by crystallographic twofold symmetry with the metal atom lying on the rotation axis. The Pd II atom exists within a slightly distorted squareplanar geometry defined by a cis-O 2S 2 donor set. The dihedral angle formed between the mean planes of the symmetry-related six-membered chelate rings is 12.88 (7)° and the bond lengths within the rings are indicative of significant electron delocalization. In the crystal, molecules aggregate into dimers linked by four C-H⋯O interactions.
Dicyclohexylammonium thiocyanate: Monoclinic polymorph
(International Union of Crystallography, 2011-10-05) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
The title salt, C12H24N+·NCS -, represents a monoclinic polymorph of the previously reported ortho-rhom-bic form [Khawar Rauf et al. (2008). Acta Cryst. E64, o366]. Two independent formula units comprise the asymmetric unit with the major difference in their mol-ecular structures relating to the relative dispositions of the cyclohexyl rings [dihedral angles = 79.88 (6) and 67.72 (5)°]. Further, the independent anions form distinctive patterns of hydrogen-bonding interactions, i.e. 2 × N - H⋯N versus N - H⋯N and N - H⋯S. The resulting supra-molecular architecture is a supra-molecular chain along the c axis based on a square-wave topology. © Selvakumaran et al. 2011.
Dibenzylazanium chloride
(International Union of Crystallography, 2012-02-04) Selvakumaran, N; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
In the title salt, C 14H 16N +·Cl -, the complete cation and complete anion are generated by the application of mirror symmetry. The molecule is nonplanar, as seen in the dihedral angle between the terminal phenyl rings [70.92 (5)°]. In the crystal, N - H⋯Cl hydrogen bonds involving both azanium H atoms link the ions into a zigzag supramolecular chain along [100].
Kinetics and equilibrium studies for the removal of heavy metals in both single and binary systems using hydroxyapatite
(Springer Verlag, 2012-03-21) Ramesh S.T.; Rameshbabu, N; Gandhimathi, R; Nidheesh, P.V.; Srikanth Kumar, M
Removal of heavy metals is very important with respect to environmental considerations. This study investigated the sorption of copper (Cu) and zinc (Zn) in single and binary aqueous systems onto laboratory prepared hydroxyapatite (HA) surfaces. Batch experiments were carried out using synthetic HA at 30 °C. Parameters that influence the adsorption such as contact time, adsorbent dosage and pH of solution were investigated. The maximum adsorption was found at contact time of 12 and 9 h, HA dosage of 0. 4 and 0. 7 g/l and pH of 6 and 8 for Cu and Zn, respectively, in single system. Adsorption kinetics data were analyzed using the pseudofirst-, pseudosecond-order and intraparticle diffusion models. The results indicated that the adsorption kinetic data were best described by pseudosecond-order model. Langmuir and Freundlich isotherm models were applied to analyze adsorption data, and Langmuir isotherm was found to be applicable to this adsorption system, in terms of relatively high regression values. The removal capacity of HA was found to be 125 mg of Cu/g, 30. 3 mg of Zn/g in single system and 50 mg of Cu/g, 15. 16 mg of Zn/g in binary system. The results indicated that the HA used in this work proved to be effective material for removing Cu and Zn from aqueous solutions. © 2012 The Author(s).
Adsorptive removal of Pb(II) from aqueous solution using nano-sized hydroxyapatite
(Springer Verlag, 2012-10-11) Ramesh, S.T.; Rameshbabu, N; Gandhimathi, R; Srikanth Kumar, M; Nidheesh P.V.
This study investigated the sorption of Pb(II) in aqueous solution onto hydroxyapatite (HA) surfaces. Batch experiments were carried out using synthetic HA. The effect of contact time, HA dosage, and initial pH on removal efficiency were also investigated. The adsorption equilibrium and kinetics of Pb(II) on this adsorbent were then examined at 25 °C. Kinetic data were analyzed by pseudo first, second, and intra-particle diffusion models. The sorption data were then correlated with the Langmuir, Freundlich, Halsey, and Harkins-Jura adsorption isotherm models. The optimum dose of HA for Pb(II) removal is found to be 0. 12 g/l with the removal efficiency of 97. 3 % at an equilibrium contact time of 1 h. It is found that the adsorption kinetics of the Pb(II) on HA follow the pseudo second-order reaction. All the isotherms fitted well for experimental data. Capacity of HA is found as 357. 14 mg Pb(II)/g of HA. The Pb(II) immobilization mechanism was studied. The results indicated that HA can be used as an effective adsorbent for removal of Pb(II) from aqueous solution. © 2012 The Author(s).
3-Benzoyl-1-(2-methoxyphenyl)thiourea
(International Union of Crystallography, 2012-11-03) Selvakumaran, N; Sheeba, M. Mary; Karvembu, R; Ng, Seik Weng; Tiekink, Edward R. T.
In the title compound, C15H14N2O2S, the central C2N2OS moiety is planar (r.m.s. deviation of fitted atoms = 0.0336 Å). This is ascribed to the formation of an S(6) loop stabilized by an intramolecular N-H⋯O hydrogen bond; additional intramolecular N-H⋯O and C-H⋯S contacts are also noted. The dihedral angles between the central unit and the phenyl and benzene rings are 23.79 (7) and 29.52 (5)°, respectively. The thione S and ketone O atoms are mutually anti, as are the N-H H atoms; the O atoms lie to the same side of the molecule. Centrosymmetric eight-membered {⋯HNC=S}2 synthons feature in the crystal packing. The resulting inversion dimers stack along the a axis and are connected into a three-dimensional structure by C-H⋯O and C-H⋯π interactions.
1-Benzoyl-3-(4-chlorophenyl)thiourea dichloromethane hemisolvate
(International Union of Crystallography, 2012-11-10) Selvakumaran, N; Sheeba, M. Mary; Karvembu, R Ng,; Ng, Seik Weng; Tiekink, Edward R. T.
In the title hemisolvate, C14H11ClN2OS·0.5CH2Cl2, an anti disposition is found for the thione and ketone atoms, as well as the N-H H atoms; the dichloromethane C atom lies on a twofold axis. The central chromophore (including the two adjacent ipso C atoms) is planar (r.m.s. deviation = 0.021 Å) owing to the presence of an intramolecular N-H⋯O hydrogen bond, which closes an S(6) loop. Significant twists are evident in the molecule, the dihedral angles between the central moiety and the phenyl and benzene rings being 29.52 (7) and 40.02 (7)°, respectively. In the crystal, eight-membered {⋯HNC= S}2 synthons with twofold symmetry form via N-H⋯S hydrogen bonds. The dimers are connected into a supramolecular chain along [111] by C-H⋯O interactions. The chains stack along the c axis, forming columns which define channels in which the occluded dichloromethane molecules reside.
Assessment of heavy metal contamination in soil due to leachate migration from an open dumping site
(Springer Verlag, 2012-12-23) Kanmani, S; Gandhimathi, R
The concentration of heavy metals was studied in the soil samples collected around the municipal solid waste (MSW) open dumpsite, Ariyamangalam, Tiruchirappalli, Tamilnadu to understand the heavy metal contamination due to leachate migration from an open dumping site. The dump site receives approximately 400–470 tonnes of municipal solid waste. Solid waste characterization was carried out for the fresh and old municipal solid waste to know the basic composition of solid waste which is dumped in the dumping site. The heavy metal concentration in the municipal solid waste fine fraction and soil samples were analyzed. The heavy metal concentration in the collected soil sample was found in the following order: Mn > Pb > Cu > Cd. The presence of heavy metals in soil sample indicates that there is appreciable contamination of the soil by leachate migration from an open dumping site. However, these pollutants species will continuously migrated and attenuated through the soil strata and after certain period of time they might contaminate the groundwater system if there is no action to be taken to prevent this phenomenon.
Investigation of physicochemical characteristics and heavy metal distribution profile in groundwater system around the open dump site
(Springer Verlag, 2013-02-20) Kanmani, S; Gandhimathi, R
In this study, the characterization of solid waste and the effect of the leachate from an open dumping site in Ariyamangalam, Tiruchirappalli District, Tamil Nadu, on groundwater is investigated. A total of 14 groundwater samples and 20 leachate samples were collected for monitoring purpose. All the samples were analyzed for various physical and chemical parameters according to standard methods: this includes pH, electrical conductivity, total dissolved solids (TDS), total hardness, and total alkalinity, major cations such as Ca2+, Mg2+, and Fe2+, major anions such as NO3−, Cl−, and SO42− and heavy metals such as Cd, Cu, Mn, Pb, and Zn. The results indicated that, very few parameters such as pH, sulfates and nitrates concentration in the groundwater samples are within the recommended maximum admissible limits approved by WHO (World Health Organization 940–949, 2002) and Bureau of Indian standards (IS 10500:1991). The TDS (range between 740 and 14,200 mg/L) in groundwater reveal the saline behavior of water and was found to be very high according to standards. The range of chlorides in all the locations under investigation is 215.15–4,098.73 mg/L. The contour plots also indicated that the groundwater was rigorously contaminated with various heavy metals. The presence of high concentration of Pb (0.59 mg/L) in groundwater samples nearby dumping site implies that groundwater samples were contaminated by leachate migration from an open dumping site.

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