Dimethylsulfoxide-iodine catalysed deprotection of 2′-allyloxychalcones: synthesis of flavones

A new one-pot method is described for the removal of O-allyl protecting groups under oxidative conditions at neutral pH. 2′-Allyloxychalcones undergo deprotection and subsequent oxidative cyclisation to give flavones. The general applicability of the reagent has been studied.     

Detection of amitraz,a formamidine-based pesticide using chromogenic spray reagent by thin-layer chromatography

JPC – Journal of Planar Chromatography – Modern TLC - In the present study, we developed a simple, sensitive and selective thin-layer chromatographic method for the detection and...     

A comparative study of the catalytic activity of [Cu(NH3)4]2+ sorbed on zirconium phosphate and zirconium phenylphosphonate

Summary The complex cation [Cu(NH₃)₄]²⁺ has been sorbed on to two different supports: zirconium phosphate and zirconium phenylphosphonate, and the products characterized by elemental analysis, FTIR, e.s.r., reflectance spectra, t.g.a. and surface area measurements (BET method). The catalytic activity of these materials has been studied through the disproportionation of H₂O₂. The kinetic data and calculated energy of activation show that the complex cation, supported on zirconium phenylphosphonate, exhibits enhanced catalytic activity.Author to whom all correspondence should be directed.     

Formation of highly caged compounds through Diels-Alder cycloaddition of 3-bromo-7-(bromomethyl)tetracyclo[5.3.1.0<Superscript>2,6</Superscript>.0<Superscript>4,8</Superscript>]undeca-10(12)-ene-9,11-dione with itself and with cyclopentadiene

Diels-Alder reaction of the cage compound 2 with itself, leading to the highly caged compound 3 , as well as with cyclopentadiene, leading to compounds 4 and 5 , is described.     

A Review on Carbon Quantum Dot Based Semiconductor Photocatalysts for the Abatement of Refractory Pollutants

Photocatalysis is a green approach frequently utilised to eliminate a variety of environmentally hazardous refractory pollutants. Accordingly, the modification of semiconductor photocatalysts with Carbon Quantum Dots (CQDs) is of great importance for the treatment of such pollutants due to their attractive physical and chemical properties. CQDs are a perfect candidate to handle photocatalysts of high-performance since they operate as co-catalysts and as visible light harvesters. The higher separation rate of electron-hole pairs in the photocatalytic system is attributable to better photodegradation efficiency. This review classifies CQD based photocatalysts as pure, doped and composite materials and discusses the specific advantages of CQDs in visible light-driven photocatalysis. In this work, the versatile roles of CQDs in CQD-based photocatalytic systems are thoroughly discussed and summarised.     

Di- and tetranuclear ruthenium(II) and/or osmium(II) complexes of polypyridyl ligands bridged by a fully conjugated aromatic spacer: synthesis,characterization, and electrochemical and photophysical studies

A series of mono-, di-, and tetranuclear homo/heterometallic complexes of Ru(II) and Os(II) based on the bridging ligand dppz(11-11')dppz (where dppz = dipyrido[3,2-a:2',3'-c]phenazine) (BL) have been synthesized and characterized. This bridging ligand is a long rigid rod with only one rotational degree of freedom and provides complete conjugation between the chromophores. The complexes synthesized are of general formula [(bpy)(2)Ru-BL](2+), [(phen)(2)/(bpy)(2)M-BL-M(bpy)(2)/(phen)(2)](4+) (M = Ru(II) and Os(II)), [(bpy)(2)Ru-BL-Os(bpy)(2)](4+), and [((bpy)(2)Ru-BL)(3)M](8+). Detailed (1)H NMR studies of these complexes revealed that each chiral center does not influence its neighbor because of the long distance between the metal centers and the superimposed resonances of the diastereoisomers, which allowed the unambiguous assignment of the signals, particularly for homonuclear complexes. Concentration-dependent (1)H NMR studies show molecular aggregation of the mono- and dinuclear complexes in solution by pi-pi stacking. Electrospray mass spectrometry data are consistent with dimerization of mono- and dinuclear complexes in solution. Electrochemical studies show oxidations of Ru(II) and Os(II) in the potential ranges +1.38 to +1.40 and +0.92 to +1.01 V, respectively. The bridging ligand exhibits two one-electron reductions, and it appears that the added electrons are localized on the phenazene moieties of the spacer. All of these complexes show strong metal-to-ligand charge-transfer (MLCT) absorption and (3)MLCT luminescence at room temperature. Quantum yields have been calculated, and the emission lifetimes of all complexes have been measured by laser flash photolysis experiments. The luminescence intensity and lifetime data suggest that the emission due to the Ru center of the heteronuclear complexes is strongly quenched (>90%) compared to that of the corresponding model complexes. This quenching is attributed to intramolecular energy transfer from the Ru(II) center to the Os(II) center (k = (3-5) x 10(7) s(-1)) across the bridging ligand.     

Photodynamic action of Rose Bengal silica nanoparticle complex on breast and oral cancer cell lines

Rose Bengal, an anionic photosensitizer was conjugated to organically modified silica nanoparticles having 3-amino propyl groups by electrostatic or covalent interaction. The drug-nanoparticle complexes were characterized by FTIR, light scattering and zeta potential measurements. Significant changes were observed in the spectroscopic properties of the drug when it is conjugated with nanoparticles. The toxicity of the free drug and drug-nanoparticle complex was studied against oral (4451) and breast (MCF-7) cancer cell lines. Both complexes with nanoparticles were more phototoxic than free Rose Bengal, with the covalent complex being the more effective. Studies carried out on cellular uptake, photostability and singlet oxygen generation suggest that enhanced phototoxicity is primarily due to the enhanced uptake of the drug-nanoparticle complex.     

Diels–Alder reactivity of 2-(bromomethyl)-1,4-quinone and 2-bromo-5-(bromomethyl)-1,4-quinone with cyclopentadiene and the synthesis of new substituted pentacyclic systems

Photochemical synthesis of the novel compounds 3-bromotetracyclo [5.3.1.0^2,6.0^4,8] undec-10(12)-ene-9,11-dione, 1-(bromomethyl)pentacyclo [5.4.0.0^2,6.0^3,10.0^5,9]undeca-8,11-dione and 1-bromo-9-(bromomethyl)pentacyclo [5.4.0.0^2,6.0^3,10.0^5,9]undeca-8,11-dione is described.