K. R. Venugopala Reddy

Synthesis of symmmetrically substituted octabromophthalocyanine pigments and their characterisation

A convenient and a simple route has been suggested for the synthesis of symmetrically substituted metal (II) 1,3,8,10,15,17,22,24-octabromophthalocyanine pigments (MPOBr), of cobalt (CoPOBr), nickel (NiPOBr), copper (CuPOBr) and zinc (ZnPOBr). MPOBrs are synthesised from the corresponding octaaminosubstituted metal phthalocyanines, MPOAs. Synthesised complexes are investigated by elemental analysis, electronic spectra, IR spectra, magnetic susceptibility measurements, powder XRD and thermogravimatric studies to evaluate the thermal stability, crystallinity, structural integrity and purity of the complexes. The effects of substituents on the electronic spectra and the orbital contribution to the magnetic moments over a range of field strengths are discussed.

SYNTHESIS, MAGNETIC, SPECTRAL, AND THERMAL STUDIES ON METAL(II) 1,3,8,10,15,17,22,24-OCTAAMINOPHTHALOCYANINES

ABSTRACT Symmetrically octasubstituted metal(II) [M=Cu, Ni, Co, and Zn] 1,3,8,10,15,17,22,24-aminophthalocyanines have been synthesized by an efficient, simple and novel method. The aminophthalocyanines were synthesized by the reduction of the corresponding nitrophthalocyanines. The dark blue-green octaaminosubstituted phthalocyanine derivatives were characterized by elemental analyses, magnetic susceptibility, electronic, IR, thermal, and powder X-ray diffraction studies to check the purity, structural integrity, thermal stability and crystallinality of the complexes. Magnetic susceptibility studies on the above octaaminophthalocyanine complexes show a variation of the magnetic moments as a function of field strength indicating the presence of intermolecular cooperative effects. Thermal studies revealed that the complexes are stable up to 400 °C in air, and powder X-ray diffraction studies have shown that they are crystalline in nature.

Synthesis, DNA Binding, and Antimicrobial Activity of Base-Catalyzed 2-Phenyl-3-pyrido[3,2][1,3,4]thiadiazolo [3,2]quinoline Derivatives

A series of novel 3-{[(5-phenyl-1,3,4-thiadiazol-2-yl)imino] methyl}quinoline-2-thione (2a–c) and 2-phenyl-3-pyrido[3,2][1,3,4]thiadiazolo[3,2]quinoline derivatives (3a–c) were prepared by a facile synthetic method using an anhydrous potassium carbonate catalyst. The newly synthesized heterocyles were characterized by elemental analysis, FT-IR, 1H-NMR, and mass spectral data. The selected compounds were studied for interaction with calf thymus-DNA(CT-DNA) by electronic spectra and viscosity measurements, as well as thermal denaturation studies. Upon binding to DNA, the absorption spectrum underwent bathochromic and hypochromic shifts. The binding constant (Kb) observed value of 8.4 × 105 M−1 for (2a) and 8.2 × 105 M−1 for (3a) suggested that compound (2a) binds more avidly to CT-DNA than compound (3a). The increasing viscosity of sonicated rod-like DNA fragments and the melting temperature of DNA, in the presence of compound solutions, support the binding mode. The synthesized derivatives have been screened for antibacterial and antifungal activities.

Decorating nickel phthalocyanine periphery by aryl-1,3,4-oxadiazole pendants: synthesis, characterization, and conductivity studies

We have decorated nickel phthalocyanine (NiPc) periphery by four different aryl-[1,3,4]-oxadiazole pendants. Introduction of aryl-[1,3,4]-oxadiazole pendants into the NiPc core results in improved thermal stability, fine-tuning of the position of the Q-band with decrease in band gap, indicating effective electronic communication between the two different ring systems with NiPc core. The magnitude of DC electrical conductivity for aryl-[1,3,4]-oxadiazole-substituted NiPcs 3a–3d is found to be ∼105 times higher than the parent NiPc (1). The temperature-dependent DC conductivity studies reveal semiconducting nature of the newly synthesized NiPc compounds with significant decrease in thermal activation energy (ΔE) compared to parent NiPc.

DEVELOPMENT AND VALIDATION OF A STABILITY-INDICATING GRADIENT RP-UHPLC METHOD FOR THE DETERMINATION OF IMPURITIES IN ATORVASTATIN DRUG SUBSTANCE

A simple, economic, selective, and time-efficient stability-indicating reverse phase ultra-high performance liquid chromatography (UHPLC) method is reported for the purpose of determination of degradation products and impurities in Atorvastatin (ATV). The reported method was developed on a Agilent poroshell 120 Zorbax SB C-18, 2.1 mm × 100 mm 2.7 µm particle size column with chromatographic conditions such as a mobile phase comprising of acetonitrile, buffer, and tetrahydrofuran; a flow rate of 0.5 ml/min gradient programmed for 17 min; and UV detector set at 244 nm resulted in equal or better chromatographic separation when compared with conventional HPLC method. The poroshell column was selected because of its porous technology that helps in reducing 40–50% pressure compared to a 1.8-µ particle column. A forced degradation study supports the fact that the optimized and validated method is stability indicating and can be used in the routine analysis of ATV drug substance.

Synthesis, spectral, magnetic, thermal and antibacterial studies on symmetrically substituted 1,8,15,22-tetra- phenylpropene-1-imino phthalocyanines

This article describes a simple method developed for the synthesis of symmetrically substituted 1,8,15,22-tetra-phenylpropene-1-imino phthalocyanines (M-PhproImPcs) of cobalt(II), copper(II), nickel(II) and zinc(II) by condensing 1,8,15,22-tetra amino phthalocyanines with cinnamaldehyde. The dark bluish-green colored tetraimino substituted phthalocyanine derivatives were characterized by elemental analysis, electronic spectra, IR spectra, magnetic susceptibility, powder XRD and thermogravimetric analysis (TGA) to check the structural integrity and purity. The variations of magnetic moment as a function of field strength indicated the presence of intermolecular co-operative interactions. The complexes were also evaluated for their antibacterial activities.

Synthesis, Characterization, and DNA Binding Studies of S2N2 Donor Bis-Mercaptoquinoline Co(II) and Ni(II) Metal Complexes: A New Class of Antimicrobial Agent

This article describes a convenient procedure for the synthesis of metal complexes of the type [ML] [CoMPQT](1), [NiMPQT](2) where M = Co(II), Ni(II) tetradentate (S2N2) Schiff-base using 3-[(2-[(2-mercaptoquinolin-3-yl)methylene]aminophenyl)imino]methyl quinoline-2-thiol ligand (MPQT)L. The synthesized ligand and its metal complexes were characterized by elemental analysis, FT-IR, 1H NMR, mass, and electronic spectra. The mode of bonding and the geometry of the complexes have been confirmed on the basis of IR and UV-vis spectral findings and magnetic measurements. The binding property of the complexes with calf-thymus DNA was studied by absorption spectra, viscosity measurements, and thermal denaturation studies. The intrinsic binding constant (Kb) had the value 2.8 × 104 M−1 for 1 and 4.8 × 104 M−1 for 2, suggesting that complex 2 binds more strongly to CT-DNA than complex 1. The synthesized metal complexes were screened for antibacterial and antifungal activities. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Synthesis, antitumor, and DNA binding behavior of novel 4-(2-hydroxyquinolin-3-yl)-6-phenyl-5, 6 dihydropyrimidin derivatives in aqueous medium.

This article deals with the synthesis of 4-(2-hydroxyquinolin-3-yl)-6-phenyl-5,6-dihydropyrimidin derivatives (2a–f), on condensation with various aromatic aldehydes and ketones in aqueous ethanolic NaOH solution yielding the corresponding chalcones (3). These chalcones were further reacted with thiourea/urea in the presence of a base, which led to the formation of the titled derivatives (2a–f). The newly synthesized heterocyles were characterized by elemental analysis, FTIR, 1HNMR, and electronic and mass spectral data. The compounds (2a and 2b) were evulated for in vitro cyctotoxicity against human breast adenocarcinoma cell (MCF-7). In MTT cytotoxicity studies, both quinolinde derivatives were found most effective. The binding interaction behavior of the compound (2a) and (2d) with calf thymus-DNA (CT-DNA) was studied by electronic spectra, viscosity measurements, and thermal denaturation studies. On binding to CT-DNA, the absorption spectrum underwent bathochromic and hypochromic shifts. The binding constant (Kb) observed 4.3 × 105 M−1 for (2a), and 3.8 × 105 M−1 for (2d) suggested that compound (2a) binds more strongly with base pairs than (2d).

An efficient carbodiimide-mediated synthesis and DNA-binding studies of novel 2-chloro/mercapto-quinoline-fused 1,3-thiazolidinones via one-pot three-component condensation

A new and efficient method for the preparation of 2-(2-chloroquinolin-3-yl)-3-(4-methylphenyl)-1, 3-thiazolidin-4-one derivatives has been assembled by DCC:-mediated three-component one-pot reaction of amine, aldehyde, and mercaptoacetic acid. The final compounds were obtained in quantitative yields within 50 min. The synthesized compounds were characterized by elemental analysis, FT-IR, 1H-NMR, and mass spectral data. The selected compounds were studied for interaction with calf thymus DNA by electronic spectra, viscosity measurements as well as thermal denaturation studies. On binding to DNA, the absorption spectrum underwent bathochromic and hypochromic shifts. The binding constant (K b) had a value of 5.3×105 M−1 for 2a and 5.8×105 M−1 for 3a. The viscosity measurements indicated that the viscosity of sonicated rod-like DNA fragments increased.

Synthesis, characterizations and biological studies of symmetrically substituted 2, 9, 16, 23-tetra-hydroxyphenylimino phthalocyanine complexes

Abstract The recent paper describes the synthesis and characterization of metal (II) 2, 9, 16, 23-tetra-hydroxyphenylimino phthalocyanines (M–OHPhImPc) of Co (II), Cu (II), Ni (II), and Zn (II). The dark bluish green colored tetramino substituted phthalocyanine derivatives are characterized by the various physico-chemical techniques such as elemental analysis, magnetic susceptibility, UV-Visible, IR, powder X-ray diffraction, and thermogravimetric analysis to check the structural integrity, purity, and thermal stability. The variations of magnetic moment as a function of field strength indicated the presence of intermolecular co-operative interactions. The above said compounds were screened for their antibacterial and antifungal activities.