J. Keshavayya

Studies on synthesis and pharmacological activities of 1,2,4-triazolo[3,4-b]1,3,4-thiadiazoles and their dihydro analogues.

4‐Amino‐5‐substituted aryl‐3‐mercapto‐1,2,4‐triazoles are versatile synthons for constructing various biologically active heterocycles. Starting from 4‐amino‐5‐substituted aryl‐3‐mercapto‐1,2,4‐triazole 3a–c, a series of new 3,5‐disubstituted‐1,2,4‐triazolo‐[3,4‐b]1,3,4‐thiadiazoles and their 5,6‐dihydrotriazolothiadiazoles were prepared. The structures of all the newly synthesized compounds have been confirmed by elemental analysis, IR, 1H‐NMR, 13C‐NMR, and mass spectra. The antimicrobial effects of the synthesized compounds were investigated using the paper disc method. Anti‐inflammatory and analgesic activities of the synthesized compounds were assessed by carrageenan‐induced rat paw oedema method and by Eddys hot plate method, respectively. Some of the compounds exhibited promising antimicrobial activities as well as moderate to good anti‐inflammatory activity and analgesic activity.

Synthesis and antimicrobial activity of 2-substituted [4-(1,3,4-oxadiazol-2-yl methyl)] phthalazin-1(2H)-one derivatives.

A series of new 2-substituted [4-(1,3,4-oxadiazol-2-yl)methyl]phthalazin-1(2H)-one derivatives 7a-h to 9a-h were designed and synthesized from methyl (4-oxo-3,4-dihydrophthalazin-1-yl)acetate (4), which in was turn prepared from phthalic anhydride. The structure of synthesized new compounds were characterized by spectral data and screened for their antimicrobial activities against various bacteria and fungi strains. Several of these compounds showed antimicrobial activity.

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, antimicrobial and cytotoxicity studies of some novel modified Strobilurin derivatives

A series of some new 3-isoxazoline substituted methyl-3-methoxy-2-(4-oxo-3,4-dihydrophthalazin-1-yl)prop-2-enoate derivatives were designed and synthesized from methyl-(4-oxo-3,4-dihydrophthalazin-1-yl)acetate, which in turn was prepared from phthalic anhydride. The structures of synthesized new compounds were characterized by spectral data and studied for their antimicrobial activities and cytotoxicity. Several of these compounds showed good antimicrobial activity

Synthesis, spectral, magnetic and thermal studies on symmetrically substituted metal (II) 1,3,8,10,15,17,22,24-octachlorophthalocyanines

Abstract The present paper describes the synthesis and characterization of metal (II) 1,3,8,10,15,17,22,24-octachlorophthalocyanines (MPOCls) of copper (CuPOCl), cobalt (CoPOCl), nickel (NiPOCl) and zinc (ZnPOCl) by using modified Sandmayers method. The dark green coloured octachloro substituted phthalocyanine derivatives are characterized by various physico-chemical techniques like elemental analysis, magnetic susceptibility, electronic, IR, thermal and powder X-ray diffraction to check the thermal stability, structural integrity and purity. The variation of magnetic moment as a function of field strength indicated the presence of intermolecular co-operative interaction.

Synthesis, Characterization and Pharmacological Activities of 3,6-Disubstituted-1,2,4-triazolo (3,4-b)- 1,3,4-thiadiazoles and their Dihydro Analogues

4-Amino-5-aryl/heteroaryl substituted-3-mercapto-1,2,4-triazoles 3(a-d) were prepared from the corresponding aromatic carboxylic acids through a multi-step sequence. Compounds 3(a-d) were made to react with various aromatic/hetero aromatic acids and hetero aromatic aldehydes to give 3,6-disubstituted-1,2,4-triazolo [3,4-b]-1,3,4-thiadizoles and 3,6-disubstituted-5,6-dihydro-1,2,4-triazolo [3,4-b]-1,3,4-thiadizoles respectively. Elemental analysis, IR, 1H NMR and mass spectral data elucidated the structures of all newly synthesized compounds. Synthesized compounds are studied for their antibacterial, antifungal, anti-inflammatory and analgesic activities. Some of the tested compounds showed significant pharmacological 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.

Triazoles as complexing agents: synthesis, characterization and pharmacological activities of copper complexes of 4-amino-3-mercapto-5-substituted aryl-1,2,4-triazoles

Copper complexes of 4-amino-3-mercapto-5-substituted aryl-1,2,4-triazoles 2(a–j) have been prepared in the ethanolic medium and characterized by elemental analysis, IR, TGA, 1H NMR and magnetic susceptibility studies. The ligand is bidentate with SN donors of the mercapto S and amino N. Some compounds show significant anti-inflammatory and analgesic activities.

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.