Synthesis and biological evaluation of novel 4-(6-substituted quinolin-4-yl)-N-aryl thiazol-2-amine derivatives as potential antimicrobial agents

Cyclocondensation reaction of 4-(2-bromoacetyl)quinolin-1-ium bromide ( 4a–d ) with substituted arylthiourea, ( 5a–g ) afforded 4-(6-substituted quinolin-4-yl)-N-aryl/pyridyl thiazol-2-amine ( 6a-ab ). These newly synthesized derivatives were evaluated for in vitro antibacterial activity against Escherichia coli (NCIM 2574), Proteus mirabilis (NCIM 2388) (Gram-negative strains), Bacillus subtilis (NCIM 2063), Staphylococcus albus (NCIM 2178) (Gram-positive strains) and in vitro antifungal activity against Aspergillus niger (ATCC 504) and Candida albicans (NCIM 3100). Compounds 6a , 6b , 6d , 6f , 6k , and 6l showed moderate to good antibacterial activity against S. albus. Ten derivatives 6c , 6q , 6r , 6s , 6t , 6v , 6w , 6x , 6y , and 6aa , showed moderate to good activity against A. niger. N-[4-(Quinolin-4-yl)-1,3-thiazol-2-yl]pyridin-2-amine presented comparable activity against A. niger with respect to standard drug Rouconazole.     

Cation disorder and structural studies on Bi4−x Nd x Ti3O12 (0.0≤x≤2.0)

Here we report the results of combined powder X-ray and neutron diffraction studies of Bi_4?x Nd _x Ti₃O₁₂ (0.0 ≤ x ≤ 2.0) compositions. The parent Bi₄Ti₃O₁₂ has an orthorhombic lattice (space group: B2cb) with unit cell parameters a = 5.4432(5) Å, b = 5.4099(5) Å and c = 32.821(2) Å, and V = 966.5(1) ų. This orthorhombic lattice is retained in all the studied compositions. The unit cell parameters gradually decrease with Nd³⁺ ion concentration with a discontinuity at x = 0.75. Orthorhombicity of the lattice decreases with increase in Nd³⁺ content in the lattice. The orthorhombic unit cell parameters for a representative Bi₂Nd₂Ti₃O₁₂ composition are: a = 5.3834(9), b = 5.3846(9) and c = 32.784(1) Å. The observed orthorhombic distortion at x = 2.0 is very small and thus the crystal structure apparently has a pseudo-tetragonal lattice. In addition, Nd³⁺ preferentially substitutes in the perovskite slab of the Aurivillius structure. The fraction of Nd³⁺ in the fluorite slab increases with increase in Nd³⁺ contents.     

The Contrasting Recognition Behavior of β‐Cyclodextrin and Its Sulfobutylether Derivative towards 4′,6‐Diamidino‐2‐phenylindole

The noncovalent interactions between 4′, 6‐diamidino‐2‐phenylindole (DAPI) and sulfobutylether β‐cyclodextrin (SBE₇β‐CD) are evaluated by using photochemical measurements and compared with that of native β‐CD. Contrasting recognition behavior and intriguing modulations in the photochemical behavior of DAPI were observed. In particular, a large enhancement in the fluorescence emission and excited‐state lifetime were seen upon binding to SBE₇β‐CD, with the SBE₇β‐CD inclusion complex being approximately 1000 times stronger than that of β‐CD. The ensuing fluorescence “turn on” was demonstrated to be responsive to chemical stimuli, such as metal ions and adamantylanmine (AD). Upon addition of Ca²⁺/AD, nearly quantitative dissociation of the complex was established to regenerate the free dye and result in fluorescence “turn off”. The SO₃^? groups are believed to be critical for the strong and selective binding of the chromophore and the stimuli‐responsive tuning. This is as an important design criterion for the optimization of host–guest properties through supramolecular association, which is relevant for drug‐delivery applications.     

Catalytic Enantioselective 1,3‐Alkyl Shift in Alkyl Aryl Ethers: Efficient Synthesis of Optically Active 3,3′‐Diaryloxindoles

Reported is the first organocatalytic asymmetric 1,3‐alkyl shift in alkyl aryl ethers for the synthesis of chiral 3,3′‐diaryloxindoles using a chiral Brønsted acid catalyst. Preliminary results showed that each enantiomer of the 3,3′‐diaryloxindole, and a racemic mixture, showed different antiproliferative activities against HeLa cell lines by using an MTT assay.     

A New Chromogenic Spray Reagent for Detection and Identification of Monocrotophos

JPC – Journal of Planar Chromatography – Modern TLC - Sensitive and selective detection of monocrotophos after TLC is possible by use of vanillin as reagent. The product from alkaline...     

Thin-Layer Chromatographic Detection of Selected Pyrethroids with p-Benzoquinone Reagent

JPC – Journal of Planar Chromatography – Modern TLC - Cypermethrin is frequently encountered in poisoning cases in India. In TLC, the compound can be detected by spraying the plate with...     

On‐line 2D‐LC‐ESI/MS/MS determination of rifaximin in rat serum

A highly sensitive and selective on‐line two‐dimensional reversed‐phase liquid chromatography/electrospray ionization–tandem mass spectrometry (2D‐LC‐ESI/MS/MS) method was developed and validated to determine rifaximin in rat serum by direct injection. The 2D‐LC‐ESI/MS/MS system consisted of a restricted access media column for trapping proteins as the first dimension and a Waters C₁₈ column as second dimension using 0.1% aqueous acetic acid:acetonitrile as mobile phase in a gradient elution mode. Rifampacin was used as an internal standard. The linear dynamic range was 0.5–10 ng/mL (r² > 0.998). Acceptable precision and accuracy were obtained over the calibration range. The assay was successfully used in analysis of rat serum to support pharmacokinetic studies. Copyright © 2009 John Wiley & Sons, Ltd.     

Sodium Bisulfite as an Efficient and Inexpensive Catalyst for the One-pot Synthesis of 2,4,5-Triaryl-1<Emphasis Type="Italic">H</Emphasis>-imidazoles from Benzil or Benzoin and Aromatic Aldehydes

Summary. 2,4,5-Triaryl-1H-imidazoles were efficiently synthesized from benzoin or benzil, ammonium acetate, and aromatic or heteroaromatic aldehydes in the presence of sodium bisulfite as catalyst. The present protocol offers significant improvements for the synthesis of 2,4,5-triaryl-1H-imidazoles with regard to yield of products, simplicity in operation, and cheap catalyst.     

Greener approach: Ionic liquid [Et3NH][HSO4]-catalyzed multicomponent synthesis of 4-arylidene-2-phenyl-5(4H)oxazolones under solvent-free condition

We have developed simple, greener, safer multicomponent synthesis series of 4-arylidene-2-phenyl-5(4H) oxazolones 4(a-r) catalyzed by Bronsted acid ionic liquid as triethylammonium hydrogen sulfate [Et₃NH][HSO₄] and catalytic amount of acetic anhydride and sodium acetate with excellent yields (90–99%). The protocol offers economical, environmentally benign, solvent-free conditions, and recycle–reuse of the catalyst and easily available starting as benzoyl chloride 1, amino acid 2 and a variety of aldehydes 3. The cyclization followed by condensation of benzoyl chloride, amino acid, and a variety of aldehydes catalyzed by ILs [Et₃NH][HSO₄] and catalytic amount of acetic anhydride and sodium acetate. The final products were confirmed by their characterization data such as FTIR, ¹H-NMR, ¹³C-NMR, Mass, high-resolution mass spectra and were compared with its reported method.     

Boric acid catalyzed convenient synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines in aqueous media

A one-pot three-component condensation of an aldehyde, malononitrile, and thiophenol has been achieved by conventional and ultrasound method. The reaction has been catalyzed by boric acid in aqueous medium. This protocol afforded corresponding 2-amino-3,5-dicarbonitrile-6-thio-pyridines in shorter reaction times and high yields with the green aspects by avoiding toxic catalysts and solvents.