Shahzad Murtaza

PALLADIUM CATALYZED HECK-MIZOROKI AND SUZUKI-MIYAURA COUPLING REACTIONS (REVIEW)

This article is about the progress of palladium compounds as a catalyst for Heck-Mizoroki and Suzuki-Miyaura coupling reactions. Industrial catalysts with broad applicability need continuous catalyst development process through modification of ligand design, geometry and functionality. Recently catalysts have been synthesized through attachment of the activated palladium complexes on the surface of polymer support, particularly, insoluble in reaction medium. An appropriate mixture of palladium salt and ligand is also used as an important modification in some cases to get better results. We surveyed the important palladium compounds synthesized up to early 2014 for Heck-Mizoroki and Suzuki-Miyaura coupling reactions and summarize their progress in terms of ligand modification and other associated parameters.

Photophysical Investigations of Carmoisine Interacting with Conventional Cationic Surfactants Under Different pH Conditions

The present study describes the extent of interactions of an efficient food dye, Carmoisine (CAR), with conventional cationic surfactants, hexadecyltrimethylammonium bromide, and ethylhexadecyldimethylammonium bromide (EHDAB). The study was carried out by quantifying the spectral changes of CAR as a function of premicellar to postmicellar surfactant concentrations at various pH conditions. The quantification of CAR molecules entrapped by cationic micellar systems has been estimated with the help of mathematical models. Binding parameters of each surfactant were calculated using differential spectroscopic method. The enhanced solubilization of dye by switching the pH was observed. In support of the electrostatic forces, the larger and more hydrophobic head group favors the promising solubilization of CAR in the outer region of the micellar interior. These findings extend the proficiency of dye molecule as a reporter for sensing electrostatic environment in lipidic membranes and related organized assemblies.

Synthesis, structure–activity relationship and molecular docking of 3-oxoaurones and 3-thioaurones as acetylcholinesterase and butyrylcholinesterase inhibitors

The present study describes efficient and facile syntheses of varyingly substituted 3-thioaurones from the corresponding 3-oxoaurones using Lawessons reagent and phosphorous pentasulfide. In comparison, the latter methodology was proved more convenient, giving higher yields and required short and simple methodology. The structures of synthetic compounds were unambiguously elucidated by IR, MS and NMR spectroscopy. All synthetic compounds were screened for their inhibitory potential against in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Molecular docking studies were also performed in order to examine their binding interactions with AChE and BChE human proteins. Both studies revealed that some of these compounds were found to be good inhibitors against AChE and BChE.

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.

N-{4-[(5-Methyl-isoxazol-3-yl)sulfamo-yl]phen-yl}benzamide.

In the title compound, C17H15N3O4S, the five-membered isoxazole ring makes dihedral angles of 80.5 (2) and 81.3 (2)° with the two benzene rings, which form a dihedral angle of 39.81 (18)° with each other. A short intramolecular C—H⋯O contact occurs. The crystal structure is stabilized by intermolecular N—H⋯O hydrogen bonds, which generate [001] chains, and further consolidated by weak C—H⋯O interactions.

Synthesis, biological activities and docking studies of novel 2,4-dihydroxybenzaldehyde based Schiff base

The present study describes the synthesis and characterization of a series of novel Schiff bases derived from 2,4-dihydroxybenzaldehyde. The biological activities of the newly synthesized compounds were examined by investigating their antioxidant, antibacterial, antifungal, enzyme inhibition and DNA interaction potential. The potential of these compounds as an antioxidant was determined by 2,2-diphenylpicrylhydrazyl radical scavenging method. The antibacterial and antifungal activities of these compounds were assayed by the disk diffusion method, while the enzyme inhibition studies were carried out against acetylcholinesterase and butyrylcholinesterase. The aforementioned studies revealed that the newly synthesized Schiff bases can be used as potential inhibitors for cholinesterase. In addition, the molecular docking studies also agreed well with the experimental results with better interaction patterns in the cases of acetylcholinesterase and butyrylcholinesterase. The DNA binding interactions in these synthesized compounds was studied by the UV–Vis absorption titration method and the results of calculated thermodynamic parameters such as binding constant (K) and free energy change (ΔG) were calculated accordingly. Most of these Schiff bases displayed relatively higher positive values for K and larger negative values for ΔG, indicating efficient binding of these Schiff bases with the DNA. During the course of this study, we also carried out the computational analysis for the determination of the mode of binding of these compounds with the DNA structure.

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

Spectral-luminescent properties of pH-sensitive azo fluorophore in complexes with quaternary ammonium disinfectants

AbstractAzo-based organic molecules offer broad-spectrum chemical and biological applications with excellent conjugated features. The present work reports the molecular chemical stability and relative polarity of potent azo compound, 2-amino-5-[(E)-(4-hydroxyphenyl)diazenyl]benzoic acid (AHABA), as well as its interaction mechanism with quaternary ammonium surfactants (Quats) at various pH conditions. The photoluminescent properties of yellow fluorophore, AHABA, in complexes with cetrimonium bromide (CTAB) and mecetronium bromide (EHDAB) were probed by quantifying its absorption and fluorescence emission spectra as a function of various concentrations of microheterogeneous assemblies. With the help of mathematical models, the stated interactions of combinational systems (AHABA–Quats) were quantified by estimating the partition coefficient (Kx), the binding capacities (Kb), Stern–Volmer quenching constant (Ksv), and related free energies. The detailed investigation revealed that the binding and partition modes are spontaneous and the quenching mechanism is ascribed to the static quenching mode initiated by ground-state complex formation. Moreover, the results of molecular electrostatic potential (MEP) revealed that the hydrophilic character as well as the electrophilic attack on the subjected azo molecule increases as the pH of the medium increases. These findings extend the proficiency of subjected emitting fluorophore as a reporter for sensing electrostatic environment in lipidic membranes and related organized assemblies. Graphical AbstractAzo flourophore interacting with cationic surfactanta

Crystal structure of N,N'-(1,2-phenyl-ene)bis-(2-chloro-acetamide).

In the title compound, C10H10Cl2N2O2, the secondary amide groups are differently twisted relative to the benzene ring, with dihedral angles between the respective planes of 21.03 (2) and 81.22 (2)°. In the crystal, the molecules are connected by N—H⋯O and C—H⋯O hydrogen bonds, forming a two-dimensional polymeric network parallel to (001). One of the amide carbonyl O atoms accepts two H atoms in N—H⋯O and C—H⋯O interactions, forming an R 2 2(6) ring motif.

Ethyl (3E)-3-[2-(4-bromo-phenyl-sulfon-yl)hydrazin-1-yl-idene]butano-ate.

The asymmetric unit of title compound, C12H15BrN2O4S, contains two molecules (A and B), with slightly different conformations: the bromophenyl rings and the SO2 planes of the sulfonyl groups are oriented at dihedral angles of 50.2 (2) (molecule A) and 58.24 (7)° (molecule B), and the ethyl acetate groups make dihedral angles of 63.99 (19)° (A) and 65.35 (16)° (B) with their bromophenyl groups. In the crystal, both molecules exist as inversion dimers linked by pairs of N—H⋯O hydrogen bonds, which generate R 2 2(14) loops. The dimers are linked by C—H⋯O interactions.