چكيده لاتين :
A new octa functionalized calix[4]resorcinarene bearing eight hydroxamic acid groups (OFCHA) has been synthesized and its
analytical properties have been investigated. To elucidate the structure of the compound, elemental analysis, FT-IR and 1H NMR
spectral data have been used. The compound showed high affinity and selectivity for vanadium(V) in presence of large quantities
of associated metal ions. The complexation of vanadium(V) with OFCHA has a 4:1 metal: ligand stoichiometry as evaluated by
Job’s plot. A spectrophotometric method is proposed for the extractive determination of vanadium(V) in an acidic medium in the
presence of diversified matrix, and verified by ICP-AES. Under the optimum condition of acidity, solvent, interfering ions and
OFCHA concentration, the molar absorptivity of the complex is 5630 l mol-1 cm-1 at 495 nm. The system obeys Beer’s law over
the range 0.125-8.75 ىg ml-1 of vanadium(V) with Sandell sensitivity 0.009 ىg cm-2. The preconcentration factor and overall
stability constant evaluated at 25 °C were 142 and 14.18, respectively. The complexation is characterized by favorable enthalpy
and entropy changes. Liquid membrane transport studies of vanadium(V) were carried out from source to the receiving phase
under controlled conditions and a mechanism for transport is suggested. To check the validity of the proposed method, vanadium
is determined in environmental, biological samples and some standard reference materials from NIST and BCS.
