Graphene oxide functionalized chitosan-magnetite nanocomposite for removal of Cu(II) and Cr(VI) from waste water.

A novel adsorbent material for removal of metal ions from aqueous solution was made by modifying chitosan. The schiff base prepared from reaction of chitosan with 3-(p-anisyl)-4-formylsydnone was further functionalized with graphene oxide. Finally Fe3O4 nanoparticles were incorporated into the modified chitosan to obtain a novel adsorbent material. The nanocomposite made was characterized using FTIR, TGA, SEM, EDS and XRD techniques and evaluated for adsorptive removal of Cu(II) and Cr(VI) ions from aqueous solutions. The maximum adsorption capacities of the adsorbent for Cu(II) and Cr(VI) ions were found to be 111.11 and 142.85 mgg-1 respectively. The adsorption data fitted well with Langmuir isotherm model and followed pseudo second order kinetic model. Thermodynamic parameters indicated the adsorption to be spontaneous and endothermic. The desorption studies revealed the efficient recovery of adsorbate species and possible reusability of the adsorbent material.

Synthesis of pyrazole-based Schiff bases of Chitosan: Evaluation of antimicrobial activity.

In this work, a novel series of Schiff base has been reported by the reaction of Chitosan with different substituted pyrazole-4-carbaldehydes in acidic media. The synthesized compounds were characterized by Fourier-transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), X-ray diffraction (XRD) and 13C NMR techniques. Chitosan and the Schiff bases were compared for their antimicrobial activity against the bacteria; Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumonia, Escherichia coli and a fungi, Candida albicans. The results indicated stronger inhibitory effect of the Schiff bases on these microorganisms compared to Chitosan and the extent of inhibition varied with the nature of substitution.

5-(4-Chloro-phen-oxy)-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde.

In the title compound, C17H13ClN2O2, the phenyl and chloro-benzene rings are inclined to the central pyrazole ring at 40.84 (9) and 65.30 (9)°, respectively. In the crystal, pairs of C-H⋯π inter-actions link the mol-ecules into inversion dimers and C-H⋯O hydrogen bonds link these dimers into columns extended in [010]. The crystal packing exhibits short inter-molecular O⋯Cl contacts of 3.0913 (16) Å.

4-(4-Methyl-phen-yl)-2-(prop-2-yn-1-yl)phthalazin-1(2H)-one.

In the title compound, C18H14N2O, the dihedral angle between the methyl-phenyl ring and the phthalazone ring system (r.m.s. deviation = 0.034 Å) is 53.93 (9)°. In the crystal, mol-ecules are connected by C-H⋯O hydrogen bonds, forming chains along [101]. The chains are linked by π-π inter-actions [centroid-centroid distance 3.6990 (12) Å], forming layers parallel to (10-1).

(E)-N'-[4-(Di-methyl-amino)-benzyl-idene]-2-(4-methyl-phen-oxy)acetohydrazide.

In the title compound, C18H21N3O2, the dihedral angle between the benzene rings is 68.85 (11)°. In the crystal, the mol-ecules are linked by C-H⋯O and N-H⋯O hydrogen bonds, as well as weak C-H⋯π contacts, forming a three-dimensional supra-molecular architecture.

Dimethyl 2-[2-(2,4,6-tri-chloro-phen-yl)hydrazin-1-yl-idene]butane-dioate.

In the title compound, C12H11Cl3N2O4, the dihedral angle between the aromatic ring and the hydrazine (NH-N=C) grouping is 52.2 (3)°. The butanedioate groups exhibit planar conformations. An intra-molecular N-H⋯O hydrogen bond links the N-H group of the hydrazine to one of the meth-oxy groups of the butane-dioate moiety. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds and π-π inter-actions are also observed [centroid-centroid separation = 3.535 (1) Å].

N'-Benzyl-idene-2-chloro-N-(4-chloro-phen-yl)acetohydrazide.

In the title compound, C15H12Cl2N2O, the atoms not making up the chloro-benzene ring are approximately coplanar (r.m.s. deviation = 0.073 Å). The dihedral angle between these 13 atoms and the chloro-benzene ring is 67.37 (10)°. The C=O and Csp (2)-Cl groups are almost eclipsed [Cl-C-C=O = -6.5 (3)°]. In the crystal, C(6) chains linked by C-H⋯O hydrogen bonds result in [100] chains.

5-[(2-Methyl-4-nitro-1H-imidazol-1-yl)meth-yl]-1,3,4-thia-diazol-2-amine.

In the title compound, C7H8N6O2S, the dihedral angle between the imidazole and thia-diazole rings is 70.86 (15)°. In the crystal, mol-ecules are linked into [10-1] chains by N-H⋯N hydrogen bonds, which incorporate centrosymmetric R 2 (2)(8) and R 2 (2)(18) loops. The chains are linked by C-H⋯O and C-H⋯N inter-actions, generating a three-dimensional network. Very weak π-π stacking [centroid-centroid distance = 3.901 (17) Å] is also observed.

Regioselective reaction: synthesis, characterization and pharmacological activity of some new Mannich and Schiff bases containing sydnone.

A novel series of 1-substituted aminomethyl-3-[1-(4-isobutylphenyl)ethyl]-4-(3-aryl-4-sydnonylidene) amino-1,2,4-triazol-5-thiones (9), was prepared from the 3-[1-(4-isobutylphenyl)ethyl]-4-(3-aryl-4-sydnonylidene) amino 5-mercapto-1,2,4-triazoles (8) by aminomethylation with formaldehyde and secondary amine. The structures of Schiff bases (8) and Mannich bases (9) were characterized on the basis of IR, NMR, mass spectra1 data and elemental analysis. The newly synthesized compounds were screened for their anti-inflammatory and analgesic activities. Mannich bases (9) carrying piperidine and morpholine residues showed promising anti-inflammatory and analgesic activity.

Synthesis, characterization and pharmacological activity of 4-{[1-substituted aminomethyl-4-arylideneamino-5-sulfanyl-4,5-dihydro-1H-1,2,4-triazol-3-yl]methyl}-2H-1,4-benzothiazin-3(4H)-ones.

A new series of Schiff and Mannich bases derivatives (6) of 4-[(4-amino-5-sulfanyl-4H-1,2,4-triazol-3-yl)methyl]-2H-1,4-benzothiazin-3(4H)-one (4), derived from (3-oxo-2,3-dihydro-4H-1,4-benzothiazin-4-yl)acetic acid (3) were synthesized. The structures of all newly synthesized compounds were elucidated by elemental analysis, IR, (1)H NMR and mass spectral data. Synthesized compounds were evaluated for their anti-inflammatory and analgesic activity. Among the tested compounds, the (3-oxo-2,3-dihydro-4H-1,4-benzothiazin-4-yl)acetic acid (3) possess analgesic activity comparable to that of pentazocine; activity decreased on derivatization of the carboxylic acid group. However the anti-inflammatory activity of (3-oxo-2,3-dihydro-4H-1,4-benzothiazin-4-yl)acetic acid (3) increased by derivatization of the carboxylic acid group and some of the compounds showed anti-inflammatory activity comparable to that of indomethacin.

(4-Chloro-phen-yl)[1-(4-methoxy-phen-yl)-3-(5-nitro-2-fur-yl)-1H-pyrazol-4-yl]methanone.

In the title compound, C(21)H(14)ClN(3)O(5), an intra-molecular C-H⋯O hydrogen bond generates an S(7) ring motif and the furan and pyrazole rings are almost coplanar, making a dihedral angle of 1.98 (5)°. The pyrazole ring is inclined at dihedral angles of 47.59 (4) and 7.27 (4)° to the chloro-phenyl and methoxy-phenyl groups, respectively. The nitro group is almost coplanar to its attached furan ring [dihedral angle = 2.03 (12)°]. In the crystal, inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network. The crystal structure also features short inter-molecular O⋯N [2.8546 (12) Å] and Cl⋯O [3.0844 (9) Å] contacts as well as aromatic π-π stacking inter-actions [centroid-centroid distance = 3.4367 (6) Å].

2-Bromo-3-phenyl-1-(3-phenyl-sydnon-4-yl)prop-2-en-1-one.

THE TITLE SYDNONE DERIVATIVE [SYSTEMATIC NAME: 2-bromo-1-(5-oxido-3-phenyl-1,2,3-oxadiazo-lium-4-yl)-3-phenyl-prop-2-en-1-one], C(17)H(11)BrN(2)O(3), exists in a Z configuration with respect to the acyclic C=C bond. An intra-molecular C-H⋯Br hydrogen bond generates a six-membered ring, producing an S(6) ring motif. The 1,2,3-oxadiazole ring in the sydnone unit is essentially planar [maximum deviation = 0.011 (2) Å] and forms dihedral angles of 55.39 (13) and 57.12 (12)° with the two benzene rings. In the crystal structure, inter-molecular C-H⋯O hydrogen bonds link mol-ecules into two-mol-ecule-thick arrays parallel to the bc plane. The crystal structure also features a short inter-molecular N⋯C contacts [3.030 (3) Å] as well as C-H⋯π and π-π inter-actions [centroid-centroid distances = 3.3798 (11) and 3.2403 (12) Å].

[3-(5-Nitro-2-fur-yl)-1-phenyl-1H-pyrazol-4-yl](phen-yl)methanone.

In the title pyrazole compound, C(20)H(13)N(3)O(4), an intra-molecular C-H⋯O hydrogen bond generates a seven-membered ring, producing an S(7) ring motif. The essentially planar furan and pyrazole rings [maximum deviations of 0.002 (1) and 0.007 (1) Å, respectively] are coplanar with each other, forming a dihedral angle of 3.06 (10)°. The pyrazole ring forms dihedral angles of 8.51 (9) and 56.81 (9)° with the two benzene rings. The nitro group is coplanar with the attached furan ring, as indicated by the dihedral angle of 2.5 (3)°. In the crystal packing, inter-molecular C-H⋯O hydrogen bonds link adjacent mol-ecules into two-mol-ecule-wide chains along the a axis. The crystal packing is further stabilized by weak inter-molecular C-H⋯π and π-π inter-actions [centroid-centroid distance = 3.4441 (10) Å].

(E)-4-[(4-Fluoro-benzyl-idene)amino]-3-[1-(4-isobutyl-phen-yl)eth-yl]-1-(morpholino-meth-yl)-1H-1,2,4-triazole-5(4H)-thione methanol hemisolvate.

In the title compound, C(26)H(32)FN(5)OS·0.5CH(4)O, the methyl group of the methanol solvent mol-ecule is disordered over two sites with equal occupancies and the solvent is further disordered about a crystallographic twofold rotation axis. The organic mol-ecule exists in a trans configuration with respect to the acyclic C=N bond. An intra-molecular C-H⋯S hydrogen bond generates an S(6) ring motif. The morpholine ring adopts a chair conformation. The essentially planar 1,2,4-triazole ring [maximum deviation = 0.013 (2) Å] forms dihedral angles of 11.21 (10) and 67.53 (11)°, respectively, with the fluoro-phenyl unit and the isobutyl-substituted benzene ring. The crystal structure is stabilized by a weak inter-molecular C-H⋯π inter-action.

3-(2,3-Dimethyl-5-oxo-1-phenyl-2,5-di-hydro-1H-pyrazol-4-yl)sydnone.

IN THE TITLE SYDNONE COMPOUND [SYSTEMATIC NAME: 3-(2,3-dimethyl-5-oxo-1-phenyl-2,5-dihydro-1H-pyrazol-4-yl)-1,2,3-oxadiazol-3-ium-5-olate], C(13)H(12)N(4)O(3), the oxadiazole and pyrazole rings are essentially planar [maximum deviations = 0.006 (1) and 0.019 (1) Å, respectively] and are inclined at inter-planar angles of 37.84 (4) and 46.60 (4)°, respectively, with respect to the benzene ring. In the crystal, adjacent mol-ecules are inter-connected into a three-dimensional supra-molecular network via inter-molecular C-H⋯O hydrogen bonds. Weak inter-molecular π-π aromatic stacking inter-actions [centroid-centroid distance = 3.5251 (5) Å] further stabilize the crystal packing.

4-Formyl-3-p-tolyl-sydnone.

In the title compound, C(10)H(8)N(2)O(3), the oxadiazole ring is essentially planar, with a maximum deviation of 0.006 (1) Šfor the two-connected N atom. The mean planes through the aldehyde unit and the methyl-substituted phenyl ring make inter-planar angles of 13.60 (9) and 59.69 (4)°, respectively, with the oxadiazole ring. In the crystal structure, adjacent mol-ecules are inter-connected into a two-dimensional array parallel to (100) by inter-molecular C-H⋯O hydrogen bonds.

4-[3-(1-Naphthyl-oxymeth-yl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thia-diazin-6-yl]-3-p-tolyl-sydnone.

In the title sydnone compound, C(24)H(18)N(6)O(3)S {systematic name: 4-[3-(1-naphthyl-oxymeth-yl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thia-diazin-6-yl]-3-p-tolyl-4,5-dihydro-1,2,3-oxadiazol-3-ium-5-olate} an intra-molecular C-H⋯O hydrogen bond generates an S(6) ring motif. The 3,6-dihydro-1,3,4-thia-diazine ring adopts a twist-boat conformation. The essentially planar 1,2,3-oxadiazole and 1,2,4-triazole rings [maximum deviations of 0.006 (1) and 0.008 (1) Å, respectively] are inclined to one another at inter-planar angle of 44.11 (4)°. The naphthalene unit forms an inter-planar angle of 66.40 (4)° with the 1,2,4-triazole ring. In the crystal packing, pairs of inter-molecular C-H⋯O hydrogen bonds link adjacent mol-ecules into dimers incorporating R(2) (2)(12) ring motifs. Further stabilization is provided by weak C-H⋯π inter-actions.

4-(1H-Benzimidazol-2-ylmeth-yl)-2H-1,4-benzothia-zin-3(4H)-one.

In the title compound, C(16)H(13)N(3)OS, the thio-morpholine ring exists in a screw boat conformation. The angle between the benzimidazole ring system and the benzene ring fused to the thia-zine ring is 67.22 (6)°. In the crystal, mol-ecules form infinite chains along the a axis via inter-molecular N-H⋯N inter-actions. C-H⋯π inter-actions also contribute to the stability of the crystal structure.

2,2'-Dithio-dianiline: a redetermination at 100†K.

STRUCTURAL STUDIES OF THE TITLE COMPOUND [SYSTEMATIC NAME: 2,2'-(disulfanedi-yl)dianiline], C(12)H(12)N(2)S(2), were previously performed at room temperature [Gomes de Mesquita (1967 ▶). Acta Cryst.23, 671; Lee & Bryant (1970 ▶). Acta Cryst. B26, 1729; Ribar et al. (1975 ▶). Bull. Yugoslav. Crystallogr. Centre, A10, 68]. The results of the current redetermination allow a clarification of the nature of the intra- and inter-molecular N-H⋯S hydrogen bonding described in the literature for this compound. On cooling to 100 K, the unit cell contracts most in the c axis, and it changes rather less in the directions involving the strongly hydrogen-bonded chains, which are the a and b axes. In the crystal structure, N-H⋯N hydrogen bonds link neighbouring mol-ecules into two-dimensional frameworks parallel to the ab plane. An additional inter-molecular N-H⋯S hydrogen bond has also been established, based on freely refined H-atom positions. Inter-molecular C-H⋯π inter-actions further stabilize the crystal structure.

3-Phenyl-4-{3-[(p-tol-yloxy)meth-yl]-7H-1,2,4-triazolo[3,4-b][1,3,4]thia-diazin-6-yl}sydnone.

IN THE TITLE COMPOUND (SYSTEMATIC NAME: 3-phenyl-4-{3-[(p-tol-yloxy)meth-yl]-7H-1,2,4-triazolo[3,4-b][1,3,4]thia-diazin-6-yl}-1,2,3-oxadiazol-3-ium-5-olate), C(20)H(16)N(6)O(3)S, an intra-molecular C-H⋯O hydrogen bond generates an S(6) ring motif. The 3,6-dihydro-1,3,4-thia-diazine ring adopts a twist-boat conformation. The 1,2,3-oxadiazole and 1,2,4-triazole rings are inclined to each other at an inter-planar angle of 44.13 (13)°. The phenyl ring makes an inter-planar angle of 67.40 (13)° with the attached 1,2,3-oxadiazole ring. In the crystal structure, adjacent mol-ecules are inter-connected into two-mol-ecule-thick arrays parallel to (100) via C-H⋯O and C-H⋯N hydrogen bonds. A short S⋯O contact [2.9512 (18) Å] is observed.