Electronic, e.p.r., cyclic voltammetric and biological activities of copper(II) complexes with macrocyclic ligands

Abstract

Eight new macrocyclic ligands have been prepared by the reaction of the precursor diketone (benzil, glyoxal, diacetyl or 2,3-pentanedione) with a diamine (thiosemicarbazide or semicarbazide). Copper(II) complexes of these ligands have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility, i.r., u.v.-vis, 1 H-n.m.r., mass and e.p.r. spectral studies. Mass, n.m.r. and i.r. data indicate the condensation of the diamine and diketone and the whole molecular ion structure. g-Values are calculated for all of the complexes in polycrystalline form as well as in DMSO solution. Spin Hamiltonian values and bonding parameters have also been calculated which indicates that an unpaired electron is present in the d x 2 Ày 2 orbital. The metal-ligand bonding parameters shows strong in-plane r sigma and in-plane p bonding. The magnetic and spectral data indicate tetragonal geometry for all of the complexes except [CuH 2 L 4 ]Cl 2 and [CuH 2 L 4 ]Cl 2 which are square planar. From c.v. data reversible Cu II /Cu I couples are observed for these complexes. The macrocyclic complexes show more antibacterial and antiviral activity as compared to the ligands. The antibacterial activities of the compounds were tested against S. aureus, S. subtillis and E. coli.

Mn(II), Co(II), Ni(II) and Cu(II) complexes of a tertraaza macrocyclic ligand: Synthesis, characterization and biological screening

“…The values of D q in Co(II) complexes were calculated from transition energy ratio diagram using the Q 3 ./Q 2 ratio [15]. Our results are in agreement with the complexes reported earlier [24,25]. The Nephelauxetic parameter E was readily obtained by usign the relation: E = B (Complex)/B (free ion ), where B (free ion) for Mn(II) is 786 cm -1 , for Co(II) is 1120 cm -1 [26,27].…”

Synthesis, spectral characterization, in-vitro microbiological evaluation and cytotoxic activities of novel macrocyclic bis hydrazone

“…But the ratio between the anodic and cathodic currents suggests that the process is simple one-electron transfer, quasi-reversible process [36,37]. On comparing the cyclic voltammograms, we observed that the variation in oxidation and reduction potential may be due to distortion in the geometry of the complex which arises due to different anions coordinated to the metal ion [38].…”

Template synthesis, spectroscopic studies and biological activities of macrocyclic complexes derived from thiocarbohydrazide and glyoxal

“…The band present near 760 cm 21 in thiocarbohydrazide may be assigned to the free n(CvS). This band is also present in all complexes which indicates that sulphur is not coordinated to the metal atom [25,27,28].The absence of bands near 2550 cm 21 (characteristic of a thiol group) rule out the possibility of thione-thiol tautomerism [29]. The C-N stretch occurs in the range 1350-1000 cm 21 .…”