Determination of trace europium based on new fluorimetric system of europium(III) with thenoyltrifluoroacetone and N,N'-dinaphthyl-N,N'-diphenyl-3,6-dioxaoctanediamide.
In the present paper, N,N'-dinaphthyl-N,N'-diphenyl-3,6-dioxaoctanediamide acts as a specific reagent for enhancing the fluorescence intensity of Eu(III) complex with thenoyl trifluoroacetone (TTA), the spectrofluorimetric determination of trace amounts of Eu(III) based on the above system was carried out and its luminescence mechanism was studied. The excitation and emission wavelengths are 343.6 and 613.3 nm, respectively. The fluorescence intensities vary linearly with the concentration of europium(III) in the range 3.647x10(-3)-3.039 mug ml(-1) for the original fluorescence with a detection limit down to 2.279x10(-4) mug ml(-1) and the standard deviation is 0.063 mug ml(-1) for 10 times measurements, and in the range 7.598x10(-4)-0.0243 mug ml(-1) (SD=0.035 for 15 times measurements), 0.06078-0.6100 mug ml(-1) (SD=0.52 for 10 times measurements) for the first derivative fluorescence signal with a detection limit down to 8.566x10(-5) mug ml(-1). The interferences of other rare earths and some of inorganic ions are described. This method is a direct, rapid, selective and sensitive analytical method for the determination of trivalent europium in rare earth ore samples and high purity of rare earth oxides.
Conformation effects on the fluorescence spectra of europium and terbium complexes with a family of ether-amide type multipodal ligands.
Three multipodal ligands: 3,3,7,7-tetra[N-methyl-N-phenyl(acetamide)-2-oxymethyl]-5-oxanonane (La), 3,3,7,7-tetra[N-ethyl-N-phenyl(acetamide)-2-oxymethyl]-5-oxanonane (Lb), 3,3,7,7-tetra[N-benzyl-N-phenyl(acetamide)-2-oxymethyl]-5-oxanonane (Lc) and their europium and terbium nitrate and perchlorate complexes were synthesized. The 12 complexes were characterized by elemental analysis, IR, fluorescence spectroscopy and conductivity. The novel cup-like crystal structure of the Eu(III) complex with Lb and fluorescence emission properties of the complexes have also been studied. It has been showed that the nature of the anion has a great effect upon the composition of the complexes. The difference in the composition of the complexes results in the difference in the emission properties of them. The [Ln(NO3)5] group is negatively effective to the fluorescence intensity of the nitrate complexes. The luminescence intensity of Ln(III) perchlorate complex is stronger than that of nitrate complex.
One-pot synthesis of annulated pyrido[2,3-d:6,5-d]dipyrimidine derivatives using nitrogen based DBU catalyst in aqueous ethanol medium
Abstract We have reported DBU as an efficient organocatalyst for one-pot three-component synthesis of annulated pyrido[2,3- d :6,5- d ]dipyrimidine derivatives using aromatic aldehyde, thio-barbituric acid and 6-amino-uracil in aqueous ethanol under reflux. The attractive advantages of this process are mild reaction conditions, environment friendly procedure, short reaction times, easy isolation of products, and excellent yields (72–89%).