Sajjad Hussain Sumrra

Pyridine and related ligands in transition metal homogeneous catalysis

This review provides a broad overview of the literature related to the importance of pyridine and related ligands in homogeneous catalysis. In particular, it describes the various ways by which this ligand can stabilised the metal within a complex for homogeneous catalysis. We surveyed the important transition metal homogenous catalysts containing pyridine and related ligand acting as backbone for other ligands in homogeneous catalytic reactions explicitly from 2011 up to early 2014 and summarized their comparative catalytic activities.

Metal based drugs: design, synthesis and in-vitro antimicrobial screening of Co(II), Ni(II), Cu(II) and Zn(II) complexes with some new carboxamide derived compounds: crystal structures of N-[ethyl(propan-2-yl)carbamothioyl]thiophene-2-carboxamide and its copper(II) complex

Abstract A new series of compounds derived from thiophene-2-carboxamide were synthesized and characterized by IR, 1H-NMR and 13C-NMR, mass spectrometry and elemental analysis. These compounds were further used to prepare their Co(II), Ni(II), Cu(II) and Zn(II) metal complexes. All metal(II) complexes were air and moisture stable. Physical, spectral and analytical data have shown the Ni(II) and Cu(II) complexes to exhibit distorted square-planar and Co(II) and Zn(II) complexes tetrahedral geometries. The ligand (L1) and its Cu(II) complex were characterized by the single-crystal X-ray diffraction method. All the ligands and their metal(II) complexes were screened for their in-vitro antimicrobial activity. The antibacterial and antifungal bioactivity data showed that the metal(II) complexes were found to be more potent than the parent ligands against one or more bacterial and fungal strains.

Design, synthesis and in vitro bactericidal/fungicidal screening of some vanadyl(IV)complexes with mono- and di-substituted ONS donor triazoles

Abstract A new series of anti-bacterial and anti-fungal mono- and di-substituted triazoles (L1)–(L6) have been synthesized and characterized on the basis of their physical, spectral and analytical data. The ligands (L1)–(L6) on reaction with vanadyl(IV) sulphate led to the formation of vanadyl(IV) metal complexes (1)–(4). The structure of the complexes has been established on the basis of their physical, spectral and elemental analyses data. The synthesized ligands and their vanadyl(IV) complexes have been screened in vitro for anti-bacterial activity against six bacterial species such as, Escherichia coli (ATCC 25922), Shigella flexneri (ATCC 12022), Pseudomonas aeruginosa (ATCC 27853), Salmonella typhi (ATCC 14028), Staphylococcus aureus (ATCC 25923) and Bacillus subtilis (ATCC 6051) and for in vitro anti-fungal activity against six fungal strains, Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata. The screening results showed the vanadyl complexes to be more bactericidal/fungicidal against one or more bacterial/fungal species. The synthesized compounds were also subjected to brine shrimp bioassay for scrutinizing their cytotoxicity.

Synthesis, structure-activity relationship and molecular docking studies of 3- O -flavonol glycosides as cholinesterase inhibitors

The prime objective of this research work is to prepare readily soluble synthetic analogues of naturally occurring 3-O-flavonol glycosides and then investigate the influence of various substituents on biological properties of synthetic compounds. In this context, a series of varyingly substituted 3-O-flavonol glycosides have been designed, synthesized and characterized efficiently. The structures of synthetic molecules were unambiguously corroborated by IR, 1H, 13C NMR and ESI-MS spectroscopic techniques. The structure of compound 22 was also analyzed by X-ray diffraction analysis. All the synthetic compounds (21-30) were evaluated for in vitro inhibitory potential against cholinesterase enzymes. The results displayed that most of the derivatives were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with varying degree of IC50 values. The experimental results were further encouraged by molecular docking studies in order to explore their binding behavior with the active pocket of AChE and BChE enzymes. The experimental and theoretical results are in parallel with one another.

Antimicrobial metal-based thiophene derived compounds.

Abstract A novel series of thiophene derived Schiff bases and their transition metal- [Co(II), Cu(II), Zn(II), Ni(II)] based compounds are reported. The Schiff bases act as tridentate ligands toward metal ions via azomethine-N, deprotonated-N of ammine substituents and S-atom of thienyl moiety. The synthesized ligands along with their metal complexes were screened for their in vitro antibacterial activity against six bacterial pathogens (Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and Bacillus subtilis) and for antifungal activity against six fungal pathogens (Trichophytonlongifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata). The results of antimicrobial studies revealed the free ligands to possess potential activity which significantly increased upon chelation.

Synthesis, spectral characterization and computed optical analysis of potent triazole based compounds

Biologically active triazole Schiff base ligand (L) and metal complexes [Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] are reported herein. The ligand acted as tridentate and coordinated towards metallic ions via azomethine-N, triazolic-N moiety and deprotonated-O of phenyl substituents in an octahedral manner. These compounds were characterized by physical, spectral and analytical analysis. The synthesized ligand and metal complexes were screened for antibacterial pathogens against Chromohalobacter salexigens, Chromohalobacter israelensi, Halomonas halofila and Halomonas salina, antifungal bioassay against Aspergillus niger and Aspergellus flavin, antioxidant (DPPH, phosphomolybdate) and also for enzyme inhibition [butyrylcholinesterase (BChE) and acetylcholinesterase (AChE)] studies. The results of these activities indicated the ligand to possess potential activity which significantly increased upon chelation. Moreover, vibrational bands, frontier molecular orbitals (FMOs) and natural bond analysis (NBO) of ligand (1) were carried out through density functional theory (DFT) with B3lYP/6-311++G (d,p) approach. While, UV-Vis analysis was performed by time dependent TD-DFT with B3lYP/6-311++G (d,p) method. NBO analysis revealed that investigated compound (L) contains enormous molecular stability owing to hyper conjugative interactions. Theoretical spectroscopic findings showed good agreement to experimental spectroscopic data. Global reactivity descriptors were calculated using the energies of FMOs which indicated compound (L) might be bioactive. These parameters confirmed the charge transfer phenomenon and reasonable correspondence with experimental bioactivity results.

Triazole metal based complexes as antibacterial/antifungal agents

Biologically active triazole derived Schiff bases, 2-methoxy-6-[(Z)-(1H-1,2,4-triazol-3-ylimino) methyl]phenol (L1) and 4-[(Z)-(1H-1,2,4-triazol-3-ylimino)methyl]benzene-1,3-diol (L2) were prepared by condensing 3-amino-1,2,4-triazole with 2-hydroxy-3-methoxybenzaldehyde and 2,4-dihydroxybenzaldehyde in the 1 : 1 molar ratio. Structures of the synthesized ligands were characterized by IR, NMR and Mass spectral data. The ligands were complexed with the ions of V, Cr, Mn, Fe, Co, Ni, Cu, and Zn to form the complexes M : L in the 1 : 2 molar ratio. The synthesized Schiff bases potentially behaved as tridentate ligands and coordinated to metal ions via azomethine-N, triazole-N, and benzaldehyde-O. Structure elucidation of complexes involved IR, UV-Vis, MS, and molar conductance data. These compounds were tested for antibacterial activity against Halomonas halophila, Chromohalobacter israelensis, Chromohalobacter salexigens, Staphylococcus aureus, Halomonas salina, and Neisseria gonorrhoeae bacterial stains. Antifungal activity of the synthesized compounds was studied by using different fungal stains like Trichophyton Longifusus, Candida Albicans, Aspergillus Flavus, Microsporum Canis, Fusarium, Solani, and Candida Glabrata. All synthesized compounds displayed high antimicrobial activity against one or more strains.

Corrigendum to “Synthesis, structure-activity relationship and molecular docking studies of 3- O -flavonol glycosides as cholinesterase inhibitors” [Bioorg. Med. Chem. 26 (12) (2018) 3696–3706]

a Department of Chemistry, University of Gujrat, Gujrat 50700, Pakistan Department of Chemistry, Govt. College Women University, Sialkot 51300, Pakistan c Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan d Department of Chemistry, University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan e Department of Physics, University of Sargodha, Sargodha, Pakistan H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan g Department of Clinical Pharmacy, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, P.O. Box 31441, Dammam, Saudi Arabia

Metal based sulfanilamides: A note on their synthesis, spectral characterization, and antimicrobial activity

Objectives of the current study were synthesis, spectral characterization and biological screening of sulfanilamide derived Schiff bases and their metal based compounds. Sulfanilamide Schiff bases (L1–L3) were synthesized by condensation of 4-aminobenzenesulfanilamide with 1-(furan-2-yl)ethanone, 1-(thiophene-2-yl)-ethanone, and 1-acetylindoline-2,3-dione. The ligands were used for preparation of their Co(II), Ni(II), Cu(II), and Zn(II) complexes by using metals chlorides in metal: ligand (1: 2) molar ratio. All metal chelates had octahedral geometry with bidentate ligands. The ligands and their metal complexes were characterized by physical, spectral and analytical data, and screened for in-vitro antibacterial activity against six bacterial pathogens (Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus, and Bacillus subtilis) and for in vitro antifungal activity against six fungal pathogens (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani, and Candida glabrata). The results of antimicrobial studies revealed that the ligands activity was significantly increased upon chelation.

Frontier molecular, natural bond orbital, UV-VIS spectral study, solvent influence on geometric parameters, vibrational frequencies and solvation energies of 8-hydroxyquinoline

N-heterocyclic compounds have extensive biological and pharmaceutical applications. 8-Hydroxyquinoline (8-HQ) also plays a significant role in many fields of life. The excellent biological signific ...