Showing papers by "Badiadka Narayana published in 2010"

1-[3,5-Bis(4-chloro-phen-yl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone.

Abstract: In the asymmetric unit of the title compound, C17H14F2N2O, there are three independent mol­ecules (A, B and C) which differ slightly in the relative orientations of the two fluoro­phenyl rings. In mol­ecules A and C one of the fluoro­phenyl rings is disordered over two positions, with occupancy ratios of 0.72 (2):0.28 (2) for mol­ecule A and 0.67 (2):0.33 (2) for mol­ecule C. The dihedral angle between the two fluoro­phenyl rings in the independent mol­ecules lie in the range 70.3 (3)–84.0 (3)°. In the crystal structure, the mol­ecules are linked via inter­molecular C—H⋯O and C—H⋯F hydrogen bonds and π⋯π stacking inter­actions [centroid–centroid distance = 3.7508 (13) A], forming a three-dimensional network.

Synthesis and Antimicrobial Studies on New Substituted 1,3,4-Oxadiazole Derivatives Bearing 6-Bromonaphthalene Moiety

Abstract: A series of new 1,3,4-oxadiazole derivatives having 6-bromonaphthalene moiety are synthesized. 2-[(6-bromo-2-naphthyl)oxy]acetohydrazide was treated with various substituted aromatic acids in presence of POCl3 to give 2-{[(6-bromo-2-naphthyl)oxy]methyl}-5-aryl-1,3,4-oxadiazole. Also the hydrazide on treating with CS2/KOH gave 5-{[(6-bromo-2-naphthyl)oxy]methyl}-1,3,4-oxadiazole-2(3H)-thione, which was subjected to Mannich reaction to get a series of Mannich bases and with alkyl/aryl halide to give 2-{[(6-bromo-2-naphthyl)oxy]methyl}-5-[(alkyl/aryl)thio]-1,3,4-oxadiazole. The newly synthesized compounds were characterized by analytical and spectral data. Antimicrobial activities of these compounds were carried out and some of them have exhibited good activity.

Methyl 4,6-bis-(4-fluoro-phen-yl)-2-oxo-cyclo-hex-3-ene-1-carboxyl-ate.

Abstract: The 3-cyclo­hexene units adopt envelope conformations in each of the two independent mol­ecules that comprise the asymmetric unit of the title compound, C20H16F2O3. The dihedral angles between the two fluoro­phenyl rings are 79.7 (2) and 73.7 (2)° in the two mol­ecules. In one of the mol­ecules, two C—H groups of the cyclo­hexene ring are disordered over two sets of sites in a 0.818 (13):0.182 (13) ratio, the major and minor components corresponding to the two enanti­omeric forms of the mol­ecule. Weak inter­molecular C—H⋯O inter­actions help to stabilize the crystal structure.

Synthesis and characterization of some chalcones and their cyclohexenone derivatives

Abstract: A series of chalcones and their derivatives have been synthesized. Chalcones, 1-(1,3-benzodioxol-5-yl)-3-(aryl)-prop-2-en-1-ones were prepared by the aldol condensation of 1-(1,3-benzodioxol-5-yl)ethanones and aryl aldehydes. Based-catalyzed condensation of 1-(1,3-benzodioxol-5-yl)-3-(aryl)prop-2-en-1-ones with ethyl acetoacetate yields corresponding ethyl 4-(1,3-benzodioxol-5-yl)-6-(aryl)-2-oxocyclohex-3-ene-1-carboxylates. Some of the synthesized chalcones were reported in the literature; the newly synthesized compounds were characterized by single crystal X-ray studies, IR, 1H-NMR and LCMS mass spectral analysis.

3,5-Bis(4-fluorophenyl)-1-phenyl-4,5-dihydro-1H-pyrazole

Abstract: In the title compound, C21H16F2N2, the dihedral angle between the fluorophenyl groups is 66.34 (8)°, and the dihedral angle between the envelope-configured pyrazole group (N/N/C/C/C) and the benzene ring is 11.50 (9)°. The dihedral angles between the benzene and the two fluoro-substituted phenyl groups are 77.7 (6) and 16.7 (5)°. Weak C—H⋯π interactions contribute to the stability of the crystal structure.

Investigation of third-order nonlinear optical properties of conjugated benzodioxal derivatives

Abstract: An investigation of third-order nonlinear optical characterization of newly synthesized conjugated benzodioxal derivatives has been done by using nanosecond Z-scan technique at 532 nm. The molecules demonstrate self-defocusing effect with intensity dependent refractive index (n2) of the order of 10−14 cm2/W. The measured molecular TPA cross-section is ranging from 2.47 ×10−47 cm4 s/photon to 6.00 cm4 s/photon. Their input-output curves indicate that there is a clear optical power limiting behavior with the limiting threshold in the range 125–181 μJ. The main factor to exhibit the observed nonlinearity in these molecules is the presence of charge donor and acceptor groups. The increased conjugation length increases the nonlinear refraction and increased electron density enhances the nonlinear absorption. The molecules exhibit good nonlinear optical properties, comparable to those of regular azoaromatic compounds. Therefore, the molecules investigated here are promising candidates for optical power limiting devices.

3,5-Bis(4-bromo-phen-yl)-1-phenyl-4,5-dihydro-1H-pyrazole.

Abstract: In the title compound, C21H16Br2N2, the central pyrazole ring adopts an flattened envelope conformation, with the stereogenic C atom in the flap position. The deviations from planarity for this ring are relatively minor (r.m.s. deviation = 0.045 A) and the dihedral angles formed with the N- and Cimine-bound benzene rings are 7.73 (13) and 11.00 (13)°, respectively. By contrast, the benzene ring bound at the chiral C atom is almost orthogonal to the rest of the mol­ecule; the dihedral angle formed between this ring and the pyrazole ring is 79.53 (13)°. In the crystal, the packing is stabilized by C—H⋯N and C—H⋯Br inter­actions.

A new method for the spectrophotometric determination of fexofenadine hydrochloride

Abstract: A novel, sensitive and selective reaction has been proposed for the assay of fexofenadine hydrochloride (FFH) in bulk and dosage forms using chloramine-T (CAT) and two dyes malachite green (MAG) and xylene cyanol FF (XFF). Spectrophotometric method entail the addition of a known excess of chloramine-T to fexofenadine hydrochloride in hydrochloric acid medium followed by the determination of residual oxidant by reacting it with a fixed amount of malachite green, measuring the absorbance at 615 nm (method A), or xylene cyanol FF, measuring the absorbance at 612 nm (method B). The apparent molar absorptivities are calculated to be 4.09×10 4 L mol -1 cm -1 , 3.07×10 4 L mol -1 cm -1 for method A and B respectively. Both methods are of comparable accuracy and precision. There is no interference from common additives and excipients. The method has been applied to the determination of fexofenadine hydrochloride in pharmaceutical samples and the results are statistically compared with those of literature UV-spectrophotometric method by applying student's t-test and F-test.

2,3-Dibromo-1,3-bis-(4-fluoro-phen-yl)propan-1-one.

Abstract: In the title compound, C15H10Br2F2O, the dihedral angle between the two 3-fluoro-substituted benzene rings is 5.7 (5)°. The two bromine substituents on the chalcone moiety are close to anti as the Br—C—C—Br torsion angle is 176.9 (7)°. Weak C—Br⋯π inter­actions may contribute to the crystal stability.

Synthesis, Characterization and Antimicrobial Study of Some New Cyclohexenone Derivatives

Abstract: A series of chalcones and its cyclohexenone derivatives derived from 6-methoxy-2-naphthaldehyde are described. The chalcones synthesized through Claisen-Schmidt condensation reaction were treated with ethylacetoacetate in presence of NaOH to get the cyclocondensed product ethyl-4-(aryl)-6-(6-methoxy-2-naphthyl)-2-oxo-cyclohex-3-ene-1-carboxylate. The synthesized compounds were characterized from elemental analysis and spectral data. Ethyl 4-(4-chlorophenyl)-6-(6-methoxy-2-naphthyl)-2-oxo-cyclohex-3-ene-1-carboxylate (4f) was studied by single crystal X-ray diffraction. The newly synthesized compounds were screened for their antimicrobial activity.

Imidazolidine-2-thione as corrosion inhibitor for mild steel in hydrochloric acid

Abstract: The inhibition effect of imidazolidine-2-thione (IMT) on the corrosion behaviour of mild steel (MS) in 1 N HCl was studied using potentiodynamic polarization, linear polarisation resistance (LPR), electrochemical impedance spectroscopy (EIS) and adsorption studies. The effects of inhibitor concentrations, temperature, corrosion rate and surface coverage are investigated. The corrosion rate and other parameters are evaluated for different inhibitor concentrations and the probable mechanism is also proposed. The results show that IMT possesses excellent inhibiting effect for the corrosion of the MS and the inhibitor acts as a mixed type inhibitor. The inhibitor does not affects the mechanism of the electrode processes and inhibits corrosion by blocking the reaction sites. The high inhibition efficiency of IMT was due to the adsorption of inhibitor molecules on the metal surface. The decrease of surface area available for electrode reactions to take place is due to the formation of a protective film. Activation energies and enthalpies of activation in the presence and absence of IMT were determined by measuring the temperature dependence of the corrosion current.

Spectrophotometric determination of nevirapine using tetrathiocyanatocobalt(II) ion as a reagent

Abstract: A simple and rapid spectrophotometric method for the determination of nevirapine is described. The method is based on the reaction of nevirapine with tetrathiocyanatocobalt(II) ion in buffer of pH 4 to form the corresponding complex. Beer's law is obeyed in the range of 0.2 - 2.0 μg mL -1 for nevirapine. The optical parameters such as molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit were found to be 1.16× 10 4 Lmol -1 cm -1 , 2.09 X 10 -3 μg cm -2 , 0.073 μg mL -1 and 0.222 μg mL -1 respectively. The optimum reaction conditions and other analytical parameters were evaluated. The statistical evaluation of the method was examined by determining intra-day and inter-day precision. The proposed method has been successfully applied for the determination of nevirapine in pharmaceutical formulations.

Chloranilic acid: a redetermination at 100 K.

Abstract: The crystal structure of chloranilic acid, C6H2Cl2O4, was first described by Andersen in 1967 [Andersen, E. K. (1967). Acta Cryst. 22, 188–191] at room temperature using visually estimated intensities. Taking into account the importance of the title compound, we have redetermined the structure at 100 (1) K. The approximately planar mol­ecule [the maximum deviation from the mean plane through the ring is 0.0014 (9) A for the ring atoms and 0.029 (3) A for the other atoms] occupies a special position, lying across the center of symmetry. In the crystal structure, a two-dimensional hydrogen-bonded network sustained by O—H⋯O inter­actions runs approximately parallel to [101]. The two-dimensional layers are further packed in a parallel fashion, stabilized by Cl⋯Cl inter­actions [Cl⋯Cl = 3.2838 (8) A, C—Cl⋯Cl = 152.96 (6)°].

(2E)-1-(4-Bromophenyl)-3-(4-fluorophenyl)prop-2-en-1-one

Abstract: The title compound, C(15)H(10)BrFO, is isostructural with (2E)-1(4-chlorophenyl)-3-(4-fluorophenyl)prop-2-en-1-one Qiu et al. (2006). Acta Cryst. E62, o3525-o3526], but the structures of other dihalogen analogues, without fluorine, are different, although they are also isostructural within the series. The molecule is approximately flat, the dihedral angle between the ring planes being 8.49 (13)degrees. In the crystal structure, intermolecular C-H center dot center dot center dot O, C-H center dot center dot center dot F and C-H center dot center dot center dot Br hydrogen bonds link molecules into V-shaped ribbons running parallel to 101] and stacked with an interplanar distance of approximately 3.53 angstrom (centroid-vcentroid distance = 3.857 angstrom)..

New reagents for the spectrophotometric determination of ranitidine hydrochloride

Abstract: A new spectrophotometric method is proposed for the assay of ranitidine hydrochlo- ride (RNH) in bulk drug and in its dosage forms using ceric ammonium sulphate (CAS) and two dyes, malachite (MAG) green and crystal violet (CV) as reagents. The method involves the addition of a known excess of ceric ammonium sulphate to ranitidine hydrochloride in acid medium, followed by the determination of unreacted CAS by reacting with a fixed amount of malachite green or crystal violet and measuring the absorbance at 615 or 582 nm respectively against the reagent blank. The Beer's law is obeyed in the concentration range of 0.4-8.0 μg/ ml of ranitidine hydrochloride (RNH) for RNH-MAG system and 0.2-1.6μg/ml of ranitidine hydrochloride for RNH-CV system. The molar Absorptivity, Sandell's sensitivity for each sys- tem were calculated. The method has been successfully applied to the determination of raniti- dine hydrochloride in pure and dosage forms.

Spectrophotometric Determination of Ranitidine Hydrochloride Based on the Reaction with p-Dimethylaminobenzaldehyde

Abstract: A simple and sensitive spectrophotometric method is described for the determination of ranitidine hydrochloride (RNH) in pharmaceuticals. It is based on the formation of colored condensation product with p -dimethylaminobenzaldehyde (PDAB) followed by measurement of absorbance at 503 nm. The absorbance was found to increase linearly with the concentration of the drug and formed the basis for quantification. The calibration graph was linear from 50.0 to 350.0 μg mL -1 . The apparent molar absorptivity is calculated to be 0.311×10 4 L mol -1 cm -1 and the calculated Sandell’s sensitivity is 0.1132µg cm -2. . The limits of detection and quantification are found to be 0.00346 and 0.0105µg mL -1 ,respectively. The procedure is used to determine ranitidine hydrochloride in pharmaceutical products. The associated pharmaceutical materials did not interfere.

Orphenadrinium picrate picric acid.

Abstract: The asymmetric unit of the title compound N,N-dimethyl-2-[(2-methyl­phen­yl)phenyl­meth­oxy]ethanaminium picrate picric acid, C18H24NO+·C6H2N3O7−·C6H3N3O7, contains one orphenadrinium cation, one picrate anion and one picric acid mol­ecule. In the orphenadrine cation, the two aromatic rings form a dihedral angle of 70.30 (7)°. There is an intra­molecular O—H⋯O hydrogen bond in the picric acid mol­ecule, which generates an S(6) ring motif. In the crystal structure, the orphenadrine cations, picrate anions and picric acid mol­ecules are connected by strong inter­molecular N—H⋯O hydrogen bonds, π⋯π inter­actions between the benzene rings of cations and anions [centroid–centroid distance = 3.5603 (9) A] and weak C—H⋯O hydrogen bonds, forming a three-dimensional network.

The Crystal Structure of Fluphenazinium Dipicrate Dimethylsulphoxide Solvate

Abstract: The title compound, C22H28F3N3OS2+ × 2(C6H2N3O7 −) × (CH3)2SO—the picrate salt of the potent antipsychotic drug, fluphenazine—crystallizes in the triclinic P-1 space group with unit cell parameters a = 10.6333(12) A, b = 11.9696(12) A, c = 17.7036(15) A, α = 103.265(9)°, β = 98.414(9)°, γ = 102.702(10)°. The ionic fragments: the fluphenazinium dictation, and two picrate anions, are joined by means of strong N–H···O and weak C–H···O hydrogen bonds into the chains of alternating cations and anions, expanding along [010] direction. Within the chain, the picrates interact by means of short π···π interactions: the mean distance between the planes is 3.366 A; additional interaction of the same type between one of the picrates and the phenyl ring of the phenothiazine ring system additionally strengthen the pattern. The phenothiazine ring exists in a typical, “butterfly-like” conformation, with two terminal rings planar and the central ring in a slightly flattened boat form. This conformation results in the dihedral angle between the terminal rings of 41.76(5)°. The aliphatic chain which substitutes phenothiazine at N-position is not in an extended conformation, the torsion angles along this chain are 75.95(14)° and −163.96(10)°. The structure contains also the solvent—dimethylsulphoxide molecules, which are connected with the cation–anion structure by means of strong O–H···O hydrogen bonds. The ionic fragments of the title salt are joined by means of strong N–H···O and weak C–H···O hydrogen bonds into the chains of alternating cations and anions, expanding along [010] direction

4-(Methyl-sulfon-yl)piperazin-1-ium chloride.

Abstract: In the title mol­ecular salt, C5H13N2O2S+·Cl−, the complete cation is generated by crystallographic mirror symmetry, with both N atoms, the S atom and one C atom lying on the reflecting plane. The chloride ion also lies on the mirror plane. The piperazinium ring adopts a chair conformation and the N—S bond adopts an equatorial orientation. In the crystal structure, the component ions are linked into a three-dimensional framework by inter­molecular N—H⋯Cl and C—H⋯Cl hydrogen bonds.

(E)-1-(4-Bromophenyl)-3-(2-methoxyphenyl)prop-2-en-1-one

Abstract: In the title compound, C(16)H(13)BrO(2), the dihedral angle between the mean planes of the methoxy- and bromo-substituted benzene rings is 24.6 (1)degrees. The angles between the mean plane of the prop-2-en-1-one group and the 4-bromophenyl and 2-methoxyphenyl ring planes are 18.8 (1) and 6.0 (1)degrees, respectively.

Ethyl 4-(2,4-dichloro-phen-yl)-6-(6-meth-oxy-2-naphth-yl)-2-oxocyclo-hex-3-ene-1-carboxyl-ate.

Abstract: In the title compound, C26H22Cl2O4, the cyclo­hexenone ring adopts an approximate half-chair conformation, with two C atoms displaced by −0.485 (6) and 0.218 (6) A from the plane of the other four ring atoms. The dihedral angles between its four almost coplanar [maximum deviation = 0.006 (2) A] atoms and the benzene and naphthalene ring systems are 59.26 (13) and 79.94 (9)°, respectively. The dihedral angle between the aromatic rings systems is 77.14 (7)°. A short intra­molecular C—H⋯Cl contact generates an S(6) ring. In the crystal, mol­ecules are linked by C—H⋯O and C—H⋯Cl inter­actions to generate a three-dimensional network.

(E)-1-(2,5-Dichloro-3-thien-yl)-3-(3,4-dimeth-oxy-phen-yl)prop-2-en-1-one.

Abstract: In the title compound, C15H12Cl2O3S, the prop-2-en-1-one (enone) fragment is almost planar [C—C—C—O = 2.2 (4)°] and it subtends dihedral angles of 11.9 (2) and 11.0 (2)° with the thio­phene and benzene rings, respectively. The dihedral angle between the aromatic rings is 3.47 (16)°. In the crystal, weak C—H⋯O and C—H⋯Cl inter­actions link the mol­ecules, leading to R22(14), R22(24) and C(11) supra­molecular motifs occurring within the three-dimensional network. Weak aromatic π–π stacking [centroid–centroid separations = 3.6823 (15) and 3.8722 (15) A] may also help to consolidate the packing.

4-(4-Chloro-phen-yl)-4-hy-droxy-piperidinium maleate maleic acid solvate.

Abstract: In the cation of the title compound, C11H15ClNO+·C4H3O4−·C4H4O4, the dihedral angle between the mean planes of the chlorine-substituted aromatic ring and the 4-hy­droxy­piperidinium ring (C–C–C–C–C–N) is 61.9 (8)°. Intra­molecular O—H⋯O and inter­molecular O—H⋯O and N—H⋯O hydrogen bonding, as well as weak π-stacking inter­actions [centroid–centroid distance = 3.646 (5) A] help to establish the packing.

Synthesis, Characterization, and Antiproliferative Activity of 2-(2-Bromo-5-methoxyphenyl)-6-aryl-1,3-thiazolo[3,2b][1,2,4]triazoles

Abstract: Eight new 2-(2-bromo-5-methoxyphenyl)-6-aryl-1,3-thiazolo[3,2-b][1,2,4]triazoles were synthesized by treating 5-(2-bromo-5-methoxyphenyl)-4H-1,2,4-triazole-3-thiol with phenacyl bromides. The new products were characterized by spectroscopic and analytical methods. Five of the new compounds were evaluated for their antiproliferative activity. 2-(2-Bromo-5-methoxyphenyl)-6-(3,4-dihydroxyphenyl)-1,3-thiazolo[3,2-b] [1,2,4]triazole exhibited promising activity. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

3-(3-Bromo-4-methoxy­phen­yl)-1,5-diphenyl­pentane-1,5-dione

Abstract: In the title compound, C24H21BrO3, the central bromo­methoxy­benzene ring forms dihedral angles of 63.6 (1) and 60.3 (1)° with the terminal phenyl rings, while the angle between the two phenyl rings is 25.8 (1)°. The crystal structure is stabilized by weak C—H⋯Br and C—H⋯O hydrogen bonds, and C—H⋯π and π–π stacking [centroid–centroid distance = 3.910 (3) A] inter­actions.

Bis(2-{[3-methyl-4-(2,2,2-trifluoro-eth-oxy)-2-pyrid-yl]methyl-sulfan-yl}-1H,3H-benzimidazolium) 2,5-dichloro-3,6-dioxocyclo-hexa-1,4-diene-1,4-diolate.

Abstract: The title salt, 2C16H15F3N3OS+·C6Cl2O42−, is composed of two independent cations of a lansoprazole {systematic name 2-([3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methylsulfinyl)-1H-benzo[d]imidazole} inter­mediate and a dianion of chloranilic acid. In the cations of the lansoprazole inter­mediate, the dihedral angles between the least-squares planes of the pyridine and benzimidazole rings are 11.1 (6) and 13.1 (5)°, respectively. The dihedral angles between the mean plane of the benzene ring in the chloranilic acid dianion and the pryidine and benzimidazole rings of the two lansoprazole inter­mediate groups are 71.8 (1)/80.5 (7) and 74.2 (4)/74.8 (6)°. In addition to ionic bond inter­actions, the lansoprazole inter­mediate and chloranilic ions are connected by strong N—H⋯O hydrogen bonds, which produce a set of extended O—H⋯O—H⋯O—H chains along the b axis in the (011) plane. In addition, weak C—H⋯O, C—H⋯F, N—H⋯Cl and π–π [centroid–centroid distances = 3.5631 (15), 3.8187 (13), 3.7434 (17) and 3.842 (2) A] inter­molecular inter­actions are observed, which contribute to crystal packing stability.

(E)-1-(4-Methyl­phen­yl)ethanone [8-(trifluoro­meth­yl)quinolin-4-yl]hydrazone

Abstract: In the title compound, C19H16F3N3, the dihedral angle between the naphthalene and quinoline ring systems is 14.58 (8)°. The hydrazone C—N—N=C—C chain is in an extended conformation and its mean plane is nearly coplanar with the quinoline plane [dihedral angle = 3.45 (9)°]. The bond angles within the phenyl ring show the almost additive influence of the two para substituents. In the crystal, weak π–π [centroid–centroid distances = 3.779 (2) and 3.718 (1) A] and C—H⋯F directional inter­actions join the mol­ecules into centrosymmetric dimers, which are further connected into infinite zigzag chains propagating along a.

A monoclinic polymorph of 1-(4-chloro-phen-yl)-3-(4-methoxy-phen-yl)prop-2-en-1-one.

Abstract: The crystal structure of the title compound, C16H13ClO2 (II), (space group P21/c,) is a polymorph of the structure, (I), reported by Harrison, Yathirajan, Sarojini, Narayana & Indira [Acta Cryst. (2006), E62, o1647–o1649] in the ortho­rhom­bic space group Pna21. The dihedral angle between the mean planes of the 4-chloro- and 4-meth­oxy-substituted benzene rings is 52.9 (1)° in (II) compared to 21.82 (6)° for polymorph (I). The dihedral angles between the mean planes of the prop-2-en-1-one group and those of the 4-chloro­phenyl and 4-methoxy­phenyl rings are 23.3 (3) and 33.7 (1)°, respectively. in (II). The corresponding values are 17.7 (1) and 6.0 (3)°, respectively, in polymorph (I). In the crystal, weak C—H⋯π inter­actions are observed.

1-(2,5-Dichloro-3-thien-yl)ethanone: infinite sheets mediated by O⋯Cl halogen bonds.

Abstract: In the title compound, C6H4Cl2OS, the acetyl group is almost coplanar with the thio­phene ring [dihedral angle = 4.01 (2)°]. In the crystal, short inter­molecular O⋯Cl contacts [2.9494 (14) and 3.1191 (14) A] link the mol­ecules into infinite (100) sheets and aromatic π–π stacking [centroid–centroid separation = 3.5422 (10) A] consolidates the packing.