Preparation, magnetic and EPR spectral studies of copper(II) complexes of an anticancer drug analogue

Abstract

Ten new copper(II) complexes of five potential bisthiocarbohydrazone and biscarbohydrazone ligands were synthesized and physico-chemically characterized. The spectral and magnetic studies of compounds are consistent with the formation of asymmetric di-, tri- or tetranuclear copper(II) complexes of deprotonated forms of respective ligands. The variable temperature magnetic susceptibility measurements of all complexes show antiferromagnetic interactions between the Cu(II) centers, in agreement with very broad powder EPR spectra. However, frozen solution EPR spectral studies are found in contradiction with the solid-state magnetic studies and indicate that the complexes are not very stable in solutions; the possible fragmentations of complexes are found in agreement with MALDI MS results. The EPR spectral simulation of most of the compounds is in agreement with the presence of two uncoupled Cu(II) species in solution.

IR and ESR study of copper(II) complexes with 15N-labelled lysine and ornithine

“…The value of f increases significantly with the appearance of tetrahedral distortion to the chromophore from xOy plane that leads to an increase of g || and a decrease of A || [55]. This is the case of the Cu(II)-Lysine compound adsorbed on HY zeolite (Table 1) after a supplimentary dehydration (f ffi 170).…”

“…Because all the symmetries of the previously described monomeric species are essentially axial the appropriate spin Hamiltonian can be used [54][55][56]:…”

“…The empirical factor f, an index of tetragonal distortion, is calculated as f = g || /A || [55]. Depending on the nature of the coordinated atom its value varies from 105 to 135 for small to extreme distortion in square-planar complexes [57].…”

Structural, spectral, thermal and biological studies on (Z)-N-benzoyl-N′-(2-oxo-2-(phenylamino)acetyl)carbamohydrazonothioic acid (H2PABT) and its Cd(II), Hg(II), Zn(II) and U(VI)O22+ complexes

“…Also, the IR spectrum of U(VI)O 2 2+ complex displays bands at 930 and 878 cm -1 assignable to ν 3 and ν 1 vibrations, respectively of the dioxo-uranium [26]. The ν 3 value was used to calculate the force constant (F) and radius (R) of (U=O) [27] by the following equation:…”

Formation of an unusual copper(II) complex from the degradation of a novel tricopper(II) carbohydrazone complex

“…Complexes containing two or more metal ions are of contemporary interest because of their relevance to biological systems, as evidenced by many multicopper complexes in biology [1] and the various applications such as DNA binding [2] and antimicrobial activity [3], to name a few. Recently, we have reported EPR and magnetic features of anticancer drug analogue multinuclear Cu(II) complexes of thiocarbohydrazones and dicopper(II) complexes of carbohydrazones [4]. We, also, have reported the first self-assembled metallosupramolecular square grid of a carbohydrazone ligand [5].…”