Iodate doped chitosan (I-CS) composite was synthesized, characterized and used as an adsorbent for adsorption of Pb(II) ions from aqueous solution. The I-CS sorbent was extensively characterized by nitrogen adsorption/desorption to determine the BET surface areas and BJH pore size distribution, elemental analysis, TGA/DSC, FTIR, XRD and SEM. The influences of various chemical parameters viz. pH, contact time, dose of adsorbent and initial metal ion concentration on adsorption performance of Pb(II) ions were analyzed. Equilibrium adsorption isotherm and kinetics of adsorption has also been studied. The BET results exhibited decreased porosity and specific surface area of I-CS composite due to the blockage of internal porous cavities by incorporated iodate. The maximum removal of the Pb(II) ions using I-CS adsorbent was observed at optimum pH 6. The dose of adsorbent on the percentage removal of Pb(II) ions also has a prominent effect and maximum Pb(II) ions mitigation found at 0.5 g L⁻¹ adsorbent dose with 99% efficiency achieved in 4 h. The adsorption of Pb(II) ions shown applicability of the Langmuir and Freundlich adsorption isotherm suggests the existence of both heterogeneous surface and monolayer coverage of adsorbed molecules. The adsorption process follows pseudo-second-order kinetics. This doped composite adsorbent proved to be an effective for adsorption of Pb(II) ions from aqueous solution.

An efficiently simple protocol for the synthesis of methyl 7 amino-4-oxo-5-phenyl-2-thioxo-2, 3, 4,5-tetrahydro-1H-pyrano[2,3-d]pyrimidine-6-carboxylates via one-pot three component condensation pathway is established via microwave irradiation using varied benzaldehyde derivatives, methylcyanoacetate and thio-barbituric acid in water as a green solvent. A variety of functionalized substrates were found to react under this methodology due to its easy operability and offers several advantages like, high yields (78-94%), short reaction time (3-6 min), safety and environment friendly without used any catalyst. The synthesized compounds (4a-4k) showed comparatively good in vitro antimicrobial and antifungal activities against different strains. The Compounds 4a, 4b, 4c, 4d 4e and 4f showed maximum antimicrobial activity against Staphylococcus aureus, Bacillus cereus (gram-positive bacteria), Escherichia coli, Klebshiella pneumonia, Pseudomonas aeruginosa (gram-negative bacteria). The synthesized compound 4f showed maximum antifungal activity against Aspergillus Niger and Penicillium chrysogenum strains. Streptomycin is used as standard for bacterial studies and Mycostatin as standards for fungal studies. Structure of all newly synthesized products was characterized on the basis of IR, (1)H NMR, (13)C NMR and mass spectral analysis.

In this study, a series of thiazolidine-2,4-dione derivatives 3a-i were synthesized and evaluated for antibacterial activity against Gram-positive and Gram-negative strains of Bacillus licheniformis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Newly prepared thiazolidine (TZD) derivatives were further screened separately for in vitro antifungal activity against cultures of fungal species, namely, Aspergillus niger, Alternaria brassicicola, Chaetomium murorum, Fusarium oxysporum, Lycopodium sp. and Penicillium notatum. The electron-donating substituents (-OH and -OCH₃) and electron-withdrawing substituents (-Cl and -NO₂) on the attached arylidene moieties of five-membered heterocyclic ring enhanced the broad spectrum of antimicrobial and antifungal activities. The molecular docking study has revealed that compound 3h strongly interacts with the catalytic residues of the active site of the β-carbonic anhydrase (P. aeruginosa) and has the best docking score. In silico pharmacokinetics studies showed the drug-likeness and non-toxic nature of the synthesized compounds, which indicates the combined antibacterial, antiviral and antitumor pharmacophore sites of the targeted drug. This work demonstrates that potential TZD derivatives bind to different types of bacterial and fungal pathogens for circumventing their activities and opens avenues for the development of newer drug candidates that can target bacterial and fungal pathogens.Communicated by Ramaswamy H. Sarma.

A selective method for the synthesis of annulated pyrano[2,3-d]pyrimidines has been developed. It was shown that base catalysis is more efficient in this reaction, rather than acid catalysis as it is believed that 1,4-diazabicyclo[2.2.2]octane (DABCO) is N-type base catalyst used for the synthesis of pyrano[2,3-d]pyramidine derivatives via one-pot three component condensation reactions of various aromatic aldehydes, active methylene compounds and barbituric acid in aqueous ethanol carried at normal temperature. The potential application of DABCO in organic synthesis increasing rapidly because of its reaction simplicity, less pollution, and minimum reaction time, high yields of the biological active products, uses less toxic solvents and low cost chemicals