Preconcentration of cadmium, cobalt, copper, nickel and zinc by solvent extraction into methyl isobutyl ketone with 1,5-bis [1-(2-pyridyl) ethylidene] thiocarbonohydrazide and 1,5-bis [phenyl-(2-pyridyl) methylene] thiocarbonohydrazide

The synthesis, physicochemical properties and interactions of two new thiocarbohydrazones, namely 1,5-bis[1-(2-pyridyl) ethylidene] thiocarbonohydrazide (APTH) and 1,5-bis[phenyl-(2-pyridyl) methylene] thiocarbonohydrazide (BPTH) have been studied as well as the use of both compounds as extracting reagents. These thiocarbohydrazones form yellow complexes with bivalent metal ions, and these are extractable into methyl isobutyl ketone. Conditions for quantitative extraction of Cd(II), Co(II), Cu(II), Ni(II) and Zn(II) are established from a critical study of the effect of pH, shaking time, reagent concentration in the organic phase, ionic strength and volume ratio of aqueous to organic phase.     

Structure variation and luminescence properties of lanthanide complexes with 1,9-bis [2-(2′-picolylaminoformyl)-1,4,7,9-tetraoxadecane

Using 1,9-salicylamide bissubstituted oxadecane ligand, 1,9-bis [2-(2′-picolylaminoformyl)-1,4,7,9-tetraoxadecane (L), two novel lanthanide complexes have been prepared and well characterized by means of elemental analysis, IR spectroscopy, UV-vis spectroscopy, TGA analysis and single-crystal X-ray diffraction. {[PrL(NO₃)₃(H₂O)₂]·CH₃OH}_n is a 1D zigzag polymer with three-dimensional supramolecular structure formed by hydrogen bonds, while [EuL(NO₃)₃(H₂O)]_n is a linear coordination polymer and present an interesting supramolecular double chain, which are very different from the structure of terbium complex reported before. The result reported herein demonstrated that steric crowding associated with the decreasing lanthanide ion radius causes changes of the conformation of the ligand as well as structures. Luminescence studies for the Eu(III) complexes demonstrated that the salicylamide ligand also exhibits a good antennae effect for the Eu(III) ion due to efficient intersystem crossing and ligand-to-metal energy transfer and the Eu(III) ion is well shielded from the surrounding environment.     

Spectrophotometric determination of cobalt(II) with 2-[di-(2-pyridyl)-methylidenehydrazino]quinoline

A simple, rapid and selective procedure for spectrophotometric determination of cobalt has been developed. Cobalt(II) forms two water-soluble complexes with 2-[di-(2-pyridyl)methylidenehydrazino]quinoline, an orange-yellow complex (lambda(max) 510 nm) in the pH range 2-12 and a pink complex (lambda(max) 530 nm) in 0.1-6M perchloric acid medium. The molar absorptivities for the orange-yellow and pink complexes are 3.65 x 10(4) and 4.1 x 10(4) 1.mole(-1).cm(-1) and Beer's law is obeyed up to 1.84 and 2.0 ppm of cobalt(II) respectively. Cobalt(II) has also been determined in alloys.