Alga-mediated facile green synthesis of silver nanoparticles: Photophysical,catalytic and antibacterial activity

A facile, convenient and green method has been employed for the synthesis of silver nanoparticles (AgNPs) using dried biomass of a green alga, Chlorella ellipsoidea. The phytochemicals from the alga, as a mild and non-toxic source, are believed to serve as both reducing and stabilizing agents. The formation of silver nanoparticles was confirmed from the appearance of a surface plasmon resonance band at 436 nm and energy dispersive X-ray spectroscopy. The transmission electron microscopy images showed the nanoparticles to be nearly spherical in shape with different sizes. A dynamic light scattering study revealed the average particle size to be 220.8 ± 31.3 nm. Fourier transform infrared spectroscopy revealed the occurrence of alga-derived phytochemicals attached to the outer surface of biogenically accessed silver nanoparticles. The powder X-ray diffraction study revealed the face-centred cubic crystalline structure of the nanoparticles. The as-synthesized biomatrix-loaded AgNPs exhibited a high photocatalytic activity for the degradation of the hazardous pollutant dyes methylene blue and methyl orange. The catalytic efficiency was sustained even after three reduction cycles. A kinetic study indicated the degradation rates to be pseudo-first order with the degradation rate being 4.72 × 10⁻² min⁻¹ for methylene blue and 3.24 × 10⁻² min⁻¹ for methyl orange. The AgNPs also exhibited significant antibacterial activity against four selected pathogenic bacterial strains.     

The development of phosphinoamine–Pd(II)–imidazole complexes: implications in room‐temperature Suzuki–Miyaura cross‐coupling reaction

The reaction of N‐methylimidazole (N‐MeIm) and N‐butylimidazole (N‐BuIm) with the complexes [PdCl₂(PPh₂py–P,N)] and [PdCl₂(PPh₂Etpy–P,N)] in the presence of NH₄PF₆ under N₂ at room temperature afforded four new cationic Pd(II) complexes [PdCl(PPh₂py–P,N)(N‐MeIm)](PF₆) ( 1 ), [PdCl(PPh₂py–P,N)(N‐BuIm)](PF₆) ( 2 ), [PdCl(PPh₂Etpy–P,N)(N‐MeIm)](PF₆) ( 4 ) and [PdCl(PPh₂Etpy‐P,N)(N‐BuIm)](PF₆) ( 5 ) in good yields, where PPh₂py is 2‐(diphenylphosphino)pyridine and PPh₂Etpy is 2‐{2‐(diphenylphosphino)ethyl}pyridine). The complexes were fully characterized. The catalytic activities of these complexes were investigated for Suzuki–Miyaura cross‐coupling reactions at room temperature. Complex 2 exhibited excellent activity compared to other analogs. Copyright © 2013 John Wiley & Sons, Ltd.     

Highly efficient amine‐based catalytic system for room temperature Suzuki–Miyaura reactions of aryl halides with arylboronic acids

An in situ‐generated catalytic system based on PdCl₂ and primary amine‐based ligand exhibited excellent activity (up to 98% isolated yield) in the Suzuki–Miyaura cross‐coupling reactions of aryl bromides with arylboronic acids in water, at room temperature, without any additive. The efficiencies of the ligands follow the order: (C₆H₅)₃CNH₂ > C₆H₅CH₂ NH₂ > C₆H₅ NH₂ > C₆H₁₁ NH₂, which is in accordance with the palladacycle forming capacity of the respective ligands. Moderate‐to‐good yields (up to 78% isolated yield) of the coupling products were also obtained with less reactive aryl chlorides as substrates at room temperature in isopropanol using an alternative protocol based on Pd(OAc)₂ and (C₆H₅)₃CNH₂. Copyright © 2011 John Wiley & Sons, Ltd.     

Iron(0), rhodium(I) and palladium(II) complexes with p‐(N,N‐dimethylaminophenyl) diphenylphosphine and the application of the palladium complex as a catalyst for the Suzuki–Miyaura cross‐coupling reaction

The reaction of p‐(N,N‐dimethylaminophenyl)diphenylphosphine [PPh₂(p‐C₆H₄NMe₂)] with [Fe₃(CO)₁₂], [Rh(CO)₂Cl]₂ and PdCl₂ resulted in three new mononuclear complexes, {Fe(CO)₄[η¹‐(P)‐PPh₂(p‐C₆H₄NMe₂)]} ( 1a ), trans‐{Rh(CO)Cl[η¹‐(P)‐PPh₂(p‐C₆H₄NMe₂)]₂} ( 2 ) and trans‐{PdCl₂[η¹‐(P)‐PPh₂(p‐C₆H₄NMe₂)]₂} ( 3 ), respectively. A small amount of dinuclear nonmetal‐metal bonded complex, {Fe₂(CO)₈[µ‐(P,N)‐PPh₂(p‐C₆H₄NMe₂)]} ( 1b ), was also isolated as a side product in the reaction of [Fe₃(CO)₁₂]. The complexes were characterized by elemental analyses, mass, IR, UV–vis, ¹H, ¹³C (except 1b) and ³¹P{¹H} NMR spectroscopy. The Pd complex 3 effectively catalyzes the Suzuki–Miyaura cross‐coupling reactions of aryl halides with arylboronic acids in water–isopropanol (1:1) at room temperature. Excellent yields (up to 99% isolated yield) were achieved. The effects of different solvents, bases, catalyst quantities were also evaluated. Copyright © 2011 John Wiley & Sons, Ltd.     

Structure and Stability of (NG)nCN3Be3+ Clusters and Comparison with (NG)BeY0/+

The noble gas binding ability of CN₃Be₃⁺ clusters was assessed both by ab intio and density functional studies. The global minimum structure of the CN₃Be₃⁺ cluster binds with four noble‐gas (NG) atoms, in which the Be atoms are acting as active centers. The electron transfer from the noble gas to the Be atom plays a key role in binding. The dissociation energy of the Be? NG bond gradually increases from He to Rn, maintaining the periodic trend. The HOMO–LUMO gap, an indicator for stability, gives additional insight into these NG‐bound clusters. The temperature at which the NG‐binding process is thermodynamically feasible was identified. In addition, we investigated the stability of two new neutral NG compounds, (NG)BeSe and (NG)BeTe, and found them to be suitable candidates to be detected experimentally such as (NG)BeO and (NG)BeS. The dissociation energies of the Be? NG bond in monocationic analogues of (NG)BeY (Y=O, S, Se, Te) were found to be larger than in the corresponding neutral counter‐parts. Finally, the higher the positive charge on the Be atoms, the higher the dissociation energy for the Be? NG bond becomes.     

Microwave-promoted efficient synthesis of spiroindenotetrahydropyridine derivatives via a catalyst- and solvent-free pseudo one-pot five-component tandem Knoevenagel/aza-Diels–Alder reaction

A microwave-assisted, one-pot pseudo five-component reaction strategy has been developed for the synthesis of some novel spiroindenotetrahydropyridine derivatives from 1,3-indanedione, an aromatic aldehyde, and ammonium acetate under catalyst- and solvent-free conditions via tandem Knoevenagel/aza-Diels–Alder reaction.     

Dinitroaliphatics as linkers: application in the synthesis of novel artemisinin carba-dimer

Abstract  

The versatility of nitroaliphatics is demonstrated by using it in the syntheses of artemisinin derived dimers. A few novel artemisinin derived dimer and monomer have been synthesized using nitroalkane as linker.     

A conceptual DFT analysis of the plausible mechanism of some pericyclic reactions

Structural Chemistry - Out of several pericyclic reactions, Diels-Alder (DA) reaction is one of the most widely used synthetic processes. In the present work, several models and methodologies have...     

Host–Guest Interactions in ExBox4+

The host–guest interaction between poly aromatic hydrocarbon/azine and the newly synthesized ExBox⁴⁺ complex is studied with the help of density functional theory. The solvent‐phase interaction energy is found to decrease with gradual substitution of methine groups (?CH?) from the six‐membered ring of guest molecules with N atoms in the resultant azine@ExBox⁴⁺ complex. The nature of the binding interaction is studied with the help of newly developed noncovalent interaction (NCI) plot program package along with energy decomposition analysis and charge decomposition analysis. The interactions are mostly π‐type van der Waals interactions.