Hizbullah Khan

Potential biosorbent derived from Calligonum polygonoides for removal of methylene blue dye from aqueous solution.

The ash of C. polygonoides (locally called balanza) was collected from Lakki Marwat, Khyber Pakhtunkhwa, Pakistan, and was utilized as biosorbent for methylene blue (MB) removal from aqueous solution. The ash was used as biosorbent without any physical or chemical treatment. The biosorbent was characterized by using various techniques such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The particle size and surface area were measured using particle size analyzer and Brunauer-Emmett-Teller equation (BET), respectively. The SEM and BET results expressed that the adsorbent has porous nature. Effects of various conditions such as initial concentration of methylene blue (MB), initial pH, contact time, dosage of biosorbent, and stirring rate were also investigated for the adsorption process. The rate of the adsorption of MB on biomass sample was fast, and equilibrium has been achieved within 1 hour. The kinetics of MB adsorption on biosorbent was studied by pseudo-first- and pseudo-second-order kinetic models and the pseudo-second-order has better mathematical fit with correlation coefficient value (R 2) of 0.999. The study revealed that C. polygonoides ash proved to be an effective, alternative, inexpensive, and environmentally benign biosorbent for MB removal from aqueous solution.

Antitumor, Antioxidant and Antimicrobial Studies of Substituted Pyridylguanidines

A series of N-pivaloyl-N′-(alkyl/aryl)-N″-pyridylguanidine of general formula C4H9CONHC(NR1R2)NPy have been synthesized and characterized using elemental analysis, FT-IR, multinuclear NMR spectroscopy, and in the case of compounds 7 and 11, by single crystal X-ray diffraction (XRD). The synthesized guanidines were tested for antitumor activities against potato tumor, and showed excellent inhibition against Agrobacterium tumefaciens (AT10)-induced tumor. The antioxidant and antimicrobial activities of these new compounds against various bacterial and fungal strains were also investigated.

Pharmacological investigations and Petra/Osiris/Molinspiration (POM) analyses of newly synthesized potentially bioactive organotin(IV) carboxylates.

A series of organotin(IV) carboxylate complexes: [Me2SnL2] (1), [n-Bu2SnL2] (2), [n-Oct2SnL2] (3), [Me3SnL] (4), [n-Bu3SnL] (5) and [Ph3SnL] (6), where L=3-(4-fluorophenyl)acrylic acid, have been successfully synthesized and characterized by FT-IR, NMR ((1)H, (13)C) and single crystal analysis. The ligand coordinates to tin atom via carboxylate group. Compound 4 was also analyzed by single crystal XRD analysis. Crystallographic data for trimethyltin(IV) complex showed that the tin has approximate trigonal bipyramidal geometry with the CH3 groups in the trigonal plane. The carboxylate groups bridge the adjacent tin atoms, resulting in polymeric chains. FT-IR and NMR data also support the 5-coordination geometry for the triorganotin(IV) derivatives. In the case of the diorganotin(IV) derivatives a six-coordinate geometry at the tin atom is proposed from spectroscopic data. The Me-Sn-Me bond angle in complexes 1 and 4 was determined from the (2)J[(119)Sn-(1)H] value as 138.4° and 111° that falls in the range of 5-coordinated trigonal bipyramidal and 6-coordinated octahedral geometries, respectively. The synthesized compounds were screened for their biological activities including antibacterial, antifungal and cytotoxicity. The compounds 4-6 exhibit excellent antibacterial, antifungal and cytotoxic activities. The cytotoxicity data reveals that the HL and 1-3 are almost non-toxic and exhibited LD50 values in the range 73.45-675.1μg/mL while 4-6 are found to be cytotoxic to mildly cytotoxic with LD50 values in the range 6.43-13.49μg/mL. The compound interacts with DNA via intercalation of aromatic ring into the base pairs of DNA resulting in hypochromism and minor red shift.

1-Methyl-1H-benzimidazole-2(3H)-thione.

The title compound, C8H8N2S, was prepared by the condensation of N-methyl-1,2-phenylenediamine and carbon disulfide. The crystal structure is stabilized by a C—H⋯π interaction between a benzene H atom and the benzene ring of a neighbouring molecule, and by intermolecular N—H⋯S interactions.

[(Methyl-carbamothio-yl)disulfan-yl]methyl N-methyl-carbamodithio-ate.

The title compound, C5H10N2S5, was unintentionally obtained as the product of an attempted synthesis of a methylcarbamodithioic acid using methylamine and carbon disulfide. In the molecule, two dithiocarbamate groups are bridged by a –CH2S– unit. The C—S—S—C torsion angle is −90.13 (11)°. The crystal structure is stabilized by N—H⋯S interactions between neighbouring molecules. An intramolecular N—H⋯S hydrogen bond also occurs.

Synthesis, Structural Characterization, and Evaluation of the Biological Properties of Heteroleptic Palladium(II) Complexes

Five heteroleptic palladium(II) complexes of the general formula Pd(PR3)(tu)Cl2, where PR3 = triphenylphosphine (1), diphenyl-o-tolylphosphine (2), diphenyl-p-tolylphosphine (3), diphenyl-t-butylphosphine (4), and diphenyl-o-methoxyphenylphosphine (5), and tu = 1,3-bis(2-methoxyphenyl) thiourea. They all have been synthesized and characterized by various spectroscopic techniques (elemental analysis, FTIR, and 1H NMR and the ligand 1,3-bis(2-methoxyphenyl) thiourea was synthesized by single crystal X-ray diffraction technique). The synthesized compounds were screened for their antibacterial activity against four strains of bacteria (Escherichia coli, Shigella flexneri, Staphylococcus aureus, and Bacillus subtilis). The antitumor potential was evaluated in terms of activity against brine shrimp eggs and DNA interaction. The mixed ligand complexes have exhibited moderate antibacterial activity and promising antitumor potential.