Synthesis, spectroscopic, and biological studies on copper(II) complexes containing equatorial–apical chloride bridges: crystal structure of [Cu₂(μ-Cl)₂(O-2-butoxyethylpyridine-2-carboximidate)₂Cl₂]

Abstract

Three new [Cu₂(μ-Cl)₂(O-2-alkoxyethylpyridine-2-carboximidate)₂Cl₂] complexes, where alkoxy = methoxy, ethoxy, and butoxy, were synthesized and characterized by elemental analyses, FTIR spectra, electronic spectra, EPR, conductance, magnetic moment, powdered X-ray powder diffraction, and X-ray single-crystal diffraction. The three complexes contain chloride as a bridging ligand and in each complex the planar bidentate ligand binds the metal ion via the pyridine-N and the NH of the imino ether group. The X-ray crystal structure of [Cu₂(μ-Cl)₂(O-2-butoxyethylpyridine-2-carboximidate)₂Cl₂] shows that it crystallizes as a centrosymmetric dinuclear species in which each copper(II) is in a distorted square pyramid. Magnetic field-induced partial molecular alignment has been observed in polycrystalline samples of 2 and 3 when cooled in a magnetic field of 1 T at 77 K. The interaction of these complexes with Calf thymus DNA has been explored and the values of binding constant, K_b for 1, 2, and 3 are 1.524 × 10³, 5.587 × 10³, and 6.362 × 10³ (ML⁻¹)⁻¹, respectively. Complexes were screened for antimicrobial activities by the agar well diffusion technique.

Graphical Abstract

Keywords:

• 2-Cyanopyridine
• Bridging ligand
• EPR
• Triclinic
• Field-induced

Acknowledgement

One of the authors (R.K. Bindiya Devi) gratefully acknowledges the financial support from the UGC-BSR fellowship.