Muhammad Nadeem Arshad

Synthesis of 2-acylated and sulfonated 4-hydroxycoumarins: In vitro urease inhibition and molecular docking studies

Sixteen 4-hydroxycoumarin derivatives were synthesized, characterized through EI-MS and (1)H NMR and screened for urease inhibitory potential. Three compounds exhibited better urease inhibition than the standard inhibitor thiourea (IC50=21±0.11μM) while other four compounds exhibited good to moderate inhibition with IC50 values between 29.45±1.1μM and 69.53±0.9μM. Structure activity relationship was established on the basis of molecular docking studies, which helped to predict the binding interactions of the most active compounds.

Hg2+ Sensor Development Based on (E)-N′-Nitrobenzylidene-Benzenesulfonohydrazide (NBBSH) Derivatives Fabricated on a Glassy Carbon Electrode with a Nafion Matrix

Three novel derivatives of (E)-N′-nitrobenzylidene-benzenesulfonohydrazide (NBBSH) were synthesized by a condensation method from nitrobenzaldehyde and benzenesulfonylhydrazine reactants in low to moderate yields, which crystallized in methanol, acetone, ethyl acetate, and ethanol. NBBSH derivatives were totally characterized using various spectroscopic techniques, such as Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, proton nuclear magnetic resonance spectroscopy (1H NMR), and carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy. The molecular structure of the NBBSH derivates was confirmed by the single crystal X-ray diffraction method and used for potential detection of a selective heavy metal ion, mercury (Hg2+), by a reliable I–V method. A thin coating of NBBSH derivatives was deposited on a glassy carbon electrode (surface area = 0.0316 cm2) with a binder (nafion) coating to modify a sensitive and selective Hg2+ sensor with a short response time in phosphate buffer. The modified cationic sensor exhibited enhanced chemical performances, such as higher sensitivity, linear dynamic range, limit of detection (LOD), reproducibility, and long-term stability toward Hg2+. The calibration curve was found to be linear over a wide range of Hg2+ concentrations (100.0 pM–100.0 mM). The sensitivity and LOD were considered to be ∼949.0 pA μM–1cm–2 and 10.0 ± 1.0 pM (S/N = 3), respectively. The sensor was applied to the selective measurement of Hg2+ in spiked water samples to give acceptable and satisfactory results.

6-Bromo-1-methyl-4-[2-(4-methyl­benzyl­idene)hydrazinyl­idene]-3H-2λ6,1-benzothia­zine-2,2-dione

In the title compound, C17H16BrN3O2S, the two fused rings are twisted by a dihedral angle of 6.61 (15)°. The thiazine ring adopts a sofa conformation. The toluene ring is oriented at dihedral angles of 15.5 (2) and 20.6 (2)° with respect to the bromobenzene and thiazine rings, respectively. The benzylidene system is approximately planar [r.m.s. deviation = 0.0388 Å]. In the cyrstal, weak intermolecular C—H⋯O hydrogen bonds connects the molecules into a chain along the b axis.

4-Hydrazinyl­idene-1-methyl-3H-2λ6,1-benzothia­zine-2,2-dione

In the title compound, C9H11N3O2S, the thiazine ring adopts a half-chair conformation. In the crystal structure N—H⋯N hydrogen bonds connect two molecules into a centrosymmetric dimer, forming an R 2 2(6) ring motif. These dimers are further connected into chains by N—H⋯O and C—H⋯O hydrogen bonds.

Dyotropic rearrangement of bridgehead substituents in closed dithienylethenes; conjugated verses non-conjugated analogues

Type I dyotropic rearrangement reactions of halogen and methyl substituents at the bridgehead position of diarylethenes and dihydroarylethenes have been studied through density functional theory at B3LYP/6-31+G(d) level. The calculations have been performed to explore the dyotropic rearrangement as a possible factor for the elusive nature of halogenated dithienylethenes (closed). The dyotropic rearrangement process in closed dithienylethenes is then compared with the dihydro analogues. Moreover, the effect of hetero atom and conjugation is also explored through quantum mechanical calculations.

Methyl 2-benzyl-4-hy­droxy-1,1-dioxo-1,2,3,4-tetra­hydro-1λ6,2-benzothia­zine-3-carboxyl­ate

In the title compound, C17H15NO5S, the benzene ring of the fused-ring system is twisted by 11.67 (6)° with respect to the thiazine ring. The atoms of the four-atom methyl ester group and the phenyl ring of the benzyl unit are inclined at 16.50 (7) and 44.52 (3)° with respect to the thiazine ring. An intramolecular O—H⋯O hydrogen bond gives rise to a six-membered S(6) ring motif. In the crystal, molecules are extended through a C—H⋯O interaction along the a axis. C—H⋯π interactions are also observed.

2-Chloro-4-(2-iodo­benzene­sulfonamido)­benzoic acid

In the title compound, C13H9ClINO4S, the dihedral angle between the aromatic rings is 81.04 (17)°. The disposition of the I and Cl atoms attached to the two rings is anti. In the crystal, molecules are connected via O—H⋯O and N—H⋯O hydrogen bonds.

N'-[(E)-1-(4-Bromo-phen-yl)ethyl-idene]-4-hy-droxy-2-methyl-1,1-dioxo-2H-1,2-benzothia-zine-3-carbohydrazide.

The six-membered heterocycle in the title compound, C18H16BrN3O4S, adopts a sofa conformation. Intramolecular N—H⋯N and O—H⋯O hydrogen bonds stabilize the molecular conformation by forming a five- and a six-membered ring, respectively. The crystal packing is stabilized by intermolecular C—H⋯O hydrogen bonds.

Two New Steroidal Glycosides from Solanum surattense

Two new steroidal alkaloid glycosides, solanoside A (1) and solanoside B (2), were isolated from the whole plant of Solanum surattense. Their structures were elucidated on the basis of spectroscopic techniques (1D and 2D NMR, HR-EI-MS, HR-FAB-MS, IR), physical data, and chemical analysis.

Methyl 4-hy­droxy-2-meth­oxy­carbonyl­methyl-1,1-dioxo-1,2-dihydro-1λ6,2-benzothia­zine-3-carboxyl­ate

There are two independent molecules in the asymmetric unit of the title compound, C13H13NO7S, which have almost identical geometries. The thiazine ring adopts a sofa conformation in both molecules and the molecular conformations are stabilized by intramolecular O—H⋯O hydrogen bonds. Intermolecular C—H⋯O hydrogen bonds stabilize the crystal packing.