Yasser Azim

Synthesis, physico-chemical and antimicrobial screening studies on 14 and 16-membered hexaazamacrocyclic complexes bearing pendant amine groups

The synthesis and characterization of a series of 14 and 16-membered hexaazamacrocyclic complexes, which were obtained via template condensation of 1,2- diaminoethane or 1,3-diaminopropane, formaldehyde and hydrazine hydrate in the presence of first row transition metal salts are reported. Complexes of the types, [ML1(NO3)2]; [CuL1](NO3)2 and [ML2Cl2]; [CuL2]Cl2 (where M = Co(II), Ni(II) and Zn(II)), were obtained. Elemental analyses, IR spectra, 1H NMR, EPR, UV-Vis, magnetic susceptibility and conductivity measurements have ascertained the overall geometry and stereochemistry of the complexes. An octahedral geometry has been suggested for all the complexes, except for copper compounds, in which the metal centre coordinates to the four nitrogen atoms of macrocyclic ligand in a square planar fashion. These complexes were screened against different fungi and bacteria in vitro and were found to be potentially active in the concentration 5 mg mL-1.

Synthesis and Characterization of Hexaazamacrocyclic Complexes with Co(II), Ni(II), Cu(II), and Zn(II) Derived from Phthalaldehyde and 2,6‐Diaminopyridine

Abstract A novel family of hexaazamacrocyclic complexes [MLX2] [M = Co(II), Ni(II), Cu(II), and Zn(II), X = Cl or NO3] containing pyridine and imine groups as part of the macrocyclic framework have been synthesized by the condensation of o‐phthalaldehyde with 2,6‐diaminopyridine in the presence of metal ions as templates in methanol as solvent. The complexes have been characterized on the basis of elemental analyses, IR, 1H NMR, EPR, UV‐Visible, magnetic susceptibility, and conductivity measurements at room temperature. An octahedral geometry has been proposed for all of these complexes. The low conductivity data suggest their non‐ionic nature.

Synthesis and Physico‐Chemical Studies on 18‐Membered Octaazamacrocyclic Complexes of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) Ions

Abstract A new series of 18‐membered octaazamacrocyclic complexes [ML1X2] and [ML2X2] (M = Mn(II), Co(II), Ni(II), Cu(II), and Zn(II); X = Cl or NO3) have been synthesized by template condensation of o‐phthalaldehyde with hydrazine hydrate and formaldehyde or acetaldehyde in MeOH. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, FT‐IR, 1H NMR, EPR, UV spectroscopy, magnetic susceptibility, and conductivity measurements. An octahedral geometry has been suggested for all the complexes and the observed low molar conductance values indicate their non‐ionic nature.

Synthesis and Physico‐Chemical Studies on 14‐ and 16‐Membered Octaazamacrocyclic Complexes Derived from Hydrazine with Co(II), Ni(II), Cu(II), and Zn(II)

A series of 14 and 16‐membered octaazamacrocyclic complexes [ML1X2] and [ML2X2] [M = Co(II), Ni(II), Cu(II) and Zn(II), X = Cl or NO3] have been synthesized by a template condensation reaction of hydrazine with 1,3‐dibromopropane or 1,2‐dibromoethane and formaldehyde in methanol. The complexes and their overall geometry and stereochemistry have been characterized by elemental analyses, IR, 1H NMR, EPR, UV–Visible, magnetic susceptibility and conductivity measurements. An octahedral geometry is suggested for all of the complexes where two coordination sites are occupied by Cl or NO3 and the other four sites by secondary amines. The low conductivity data suggest that the complexes are non‐ionic.

Synthesis of 14‐Membered Pentaazabis(Macrocyclic) Complexes of Co(II), Ni(II), Cu(II), and Zn(II) Derived from Hydrazine and Their Physico‐chemical Studies

A novel series of bis(macrocyclic) binuclear complexes of the type [Co2LX2]X2, [Ni2LX4], [Cu2L]X4 and [Zn2LX4], (X = Cl or NO3) have been synthesized via the template condensation of hydrazine, 1,2‐diaminoethane, formaldehyde and 1,3‐dibromopropane in 1:4:4:2 molar ratio. The formation of the macrocyclic framework and the mode of bonding of the complexes have been confirmed by data obtained from elemental analyses, FT‐IR, 1H NMR, electronic spectral studies, conductivity and magnetic susceptibility measurements. An octahedral geometry is proposed for the Ni(II) and Zn(II) complexes, while the Co(II) and Cu(II) have square‐pyramidal and square‐planar geometries, respectively.

Sulfaguanidine cocrystals: Synthesis, structural characterization and their antibacterial and hemolytic analysis

Graphical abstract Figure. No caption available. HighlightsPharmaceutical cocrystals of sulfaguanidine, an antibiotic were synthesized and characterized by various solid state techniques.Cocrystals showed higher sensitivity with two fold increase in the antibacterial activity.Improved non‐hemolytic/non‐cytotoxic potential exhibited by the cocrystals. ABSTRACT Sulfaguanidine (SG), belongs to the class of sulfonamide drug used as an effective antibiotic. In the present work, using crystal engineering approach two novel cocrystals of SG were synthesized (SG‐TBA and SG‐PT) with thiobarbutaric acid (TBA) and 1,10‐phenanthroline (PT), characterized by solid state techniques viz., powder X‐ray diffraction (PXRD), fourier transform infrared spectroscopy (FT‐IR), differential scanning calorimetry (DSC) and the crystal structures were determined by single crystal X‐ray diffraction studies. A comparative antibacterial activity and hemolytic potential was done on SG drug, coformers and their cocrystals. The tested cocrystals formulations showed almost two fold higher antibacterial activity against the tested strains of bacteria Gram‐positive bacteria (S. mutans and E. faecalis) and Gram‐negative bacteria (E. coli, K. pneumonia and E. clocae) over SG alone and their coformers. Cocrystal SG‐TBA showed better antibacterial activity and reduced hemolysis, thereby, reduced cytotoxicity than SG‐PT.

Metal Ion Promoted Synthesis of Hexaaza[17]paracyclophane Derived from Terephthalaldehyde Involving Co(II), Ni(II), Cu(II), and Zn(II) and Their Physico‐chemical Properties

Abstract Schiff base type mononuclear complexes of hexaaza[17]paracyclophane [MLX2] [M = Co(II), Ni(II), Cu(II), and Zn(II); X = Cl or NO3] have been synthesized by the template condensation reaction of terephthalaldehyde, diethylenetriamine, and formaldehyde in 1:1:2:1 molar ratio in methanol. The FT‐IR, 1H NMR, and 13C NMR data indicate that not all of the nitrogen atoms of the macrocyclic ring are coordinated to the metal centre. The reflectance spectra of the solid complexes were recorded confirming the penta‐coordinated geometry around the metal centre. However, the electronic spectra suggested their octahedral environment due to the presence of strongly coordinating solvent DMSO. The magnetic moment values confirm that all of the macrocyclic complexes are high‐spin.

Metal Ion Directed Synthesis of 20‐Membered Octaaza Macrocyclic Complexes of Co(II), Ni(II), Cu(II), and Zn(II) and Their Physico‐chemical Properties

Abstract The template condensation reaction of 2,6‐diacetylpyridine and 2,6‐diaminopyridine forms a novel series of 20‐membered N8 macrocyclic complexes. The proposed stoichiometry and the nature of the macrocyclic complexes have been confirmed on the basis of elemental analyses and conductivity data, respectively. The bonding in these complexes has been envisaged from the findings of IR and 1H NMR spectral studies, while the overall geometry has been deduced from the results obtained from UV‐Visible, EPR spectral, and magnetic measurements.