A meglumine catalyst–based synthesis,molecular docking,and antioxidant studies of dihydropyrano[3, 2-b]chromenedione derivatives

A simple method was employed for the synthesis of dihydropyrano[3, 2-b]chromenedione derivatives ( 4a-o) in high yields by condensation of 5, 5-dimethylcyclohexane-1, 3-dione( 1 ), different aromatic aldehydes ( 2a-o ), and 5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one( 3 ), using meglumine as a stable and reusable catalyst. Meglumine, an amino sugar, was employed as an environmentally benign catalyst, due to its splendid properties such as being inexpensive, recyclable, and biodegradable. The accomplished protocol employs low catalyst loading and easy work-up for the synthesis of 5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one derivatives. A great asset is that without any significant loss, the catalyst could be recovered and reused for extended synthetic steps. This offer huge advantage to overcome recyclability issues. Our synthesized compounds were analyzed by IR, ¹H, ¹³C NMR, mass spectra and evaluated for their antioxidant properties by 1, 1-diphenyl-2-picryl hydrazyl radical (DPPH), hydrogen peroxide(H₂O₂), and nitric oxide (NO) scavenging methods. The correlation in exhibition of antioxidant activity was effective at all doses. The binding interactions and molecular docking studies for entitled compounds were studied against 3MNG protein; 4k exhibited marked binding affinity with excellent docking score of −7.6 Kcal/mol and emerged as a lead compound.     

Structural and luminescence properties of Dy3+ ion in strontium lithium bismuth borate glasses

Different concentrations of dysprosium doped strontium lithium bismuth borate (SLBiB) glasses were synthesized by the conventional melt quenching method and characterized through X-ray diffraction, Raman, absorption and visible luminescence spectroscopies. These Dy³⁺ doped glasses are studied for their utility for white light emitting diodes. X-ray diffraction studies revealed amorphous nature of the studied glass matrices. Coexistence of trigonal BO₃ and tetrahedral BO₄ units was evidenced by Raman spectroscopy. From the absorption spectra, Judd–Ofelt (J–O) intensity parameters, Ω_λ (λ=2, 4 and 6), have been calculated. The hypersensitivity of the transition, ⁶H_15/2→⁶F_11/2 of Dy³⁺ has been discussed based on the magnitude of Ω₂ parameter. Using J–O intensity parameters, several radiative properties such as spontaneous transition probabilities (A_R), radiative branching ratios (β_R) and radiative lifetimes (τ_R) have been determined. From the emission spectra, a strong blue emission that corresponds to the transition, ⁴F_9/2→⁶H_15/2, was observed and it also shows combination of blue, yellow and red emission bands for these glasses. In addition to that, white light emission region have been observed from these studies.     

Methylene insertion into the exocyclic P-N bonds of bis(amido)cyclodiphosphazane, cis-[Bu(H)NP(μ-BuN)]2

The 1:2 and 1:1 reactions of cis-[^tBu(H)NP(μ-^tBuN)]₂ (1) with paraformaldehyde afforded α-aminophosphonates, cis-[^tBu(H)NCH₂(O)P(μ-^tBuN)]₂ (2) and cis-[^tBu(H)NP(μ-^tBuN)₂P(O)CH₂N(H)^tBu] (3), respectively, through the insertion of a methylene moiety into the P-N bonds. The X-ray crystal structure of 2 reveals that the insertion reaction occurs selectively at the exocyclic P-N bonds of bis(amido)cyclodiphosphazane.     

Biological Studies of Some 2,4-Dichloro-5-fluorophenyl Containing Triazolothiadiazoles

Summary. A series of dichlorofluorophenyl containing triazolothiadiazoles were obtained by cyclocondensation of triazole with substituted benzoic, aryloxyacetic, and anilinoacetic acids using POCl₃ as cyclizing agent. The structures of the newly synthesized compounds were characterized and confirmed by IR, ¹H NMR, mass spectra, and elemental analysis. Selected compounds were screened for their antitubercular activity against Mycobacterium tuberculosis. The compound bearing 2,4-dichloro-5-fluorophenyl moiety at position 3, and 6 of the triazolothiadiazole showed excellent activity in vitro primary screening. Compounds with 3-chloro-4-fluorophenyl and 4-fluorophenoxymethyl moieties at position 6 of the triazolothiadiazole showed very good analgesic activity. Triazolothiadiazole with 4-chlorophenyl, 4-fluoro-3-phenoxyphenyl, and 2,4-dichloro-5-fluorophenyl moieties showed excellent antimicrobial activity against the tested strains at 6.25 μg cm⁻³ concentrations.     

Enhanced Bactericidal Activity of Modified Titania in Sunlight against Pseudomonas aeruginosa,a Water-Borne Pathogen

Photocatalyst-mediated inactivations generate reactive oxygen species and OH radicals, which induce oxidative destruction of membrane integrity, causing damage to membrane phospholipids of gram negative bacteria like Pseudomonas aeruginosa. Nanosized TiO₂ was synthesized by gel to crystalline conversion and Zr-doped TiO₂ was synthesized by pulverization using appropriate precursor. The doped nanocrystals retained the anatase phase with a marginal increase in crystallite size, averaging at 25 nm. SEM–EDX analysis of the doped sample depicts the substantial growth of grain size with 1.33 atomic weight % of zirconium. The created electron states in the doped sample act as charge carrier traps suppressing recombination which later detraps the same to the surface of the catalyst causing enhanced interfacial charge transfer. Zr-doped TiO₂ at the molecular scale exhibits better photocatalytic activity with lower bandgap energy that can respond to visible light. The redshift caused by the dopants in absorption spectra of TiO₂ facilitated the nonintrinsic sample to exhibit nearly 2-fold enhancement of photoinactivation in sunlight. Extent of photoinactivation of P. aeruginosa was observed to be complete (100%) within 150 min of sunlight exposure in the presence of modified TiO₂.