Disclosed here are a piperazine, a pyridine, and two carboxylate groups containing pentadentate ligand H2pmpa and its corresponding water-soluble Mn(II) complex (1). DFT-based structural optimization implied that the complex had pentagonal bipyramidal geometry where the axial positions were occupied by two water molecules, and the equatorial plane was constituted by the ligand ON3O donor set. Thus, a bis(aquated) disc-like Mn(II) complex has been synthesized. The complex showed higher stability compared with Mn(II)-EDTA complex [log KMnL = 14.29(3)] and showed a very high r1 relaxivity value of 5.88 mM-1 s-1 at 1.41 T, 25 °C, and pH = 7.4. The relaxivity value remained almost unaffected by the pH of the medium in the range of 6-10. Although the presence of 200 equiv of fluoride and bicarbonate anions did not affect the relaxivity value appreciably, an increase in the value was noticed in the presence of phosphate anion due to slow tumbling of the complex. Cell viability measurements, as well as phantom MR images using clinical MRI imager, consolidated the possible candidature of complex 1 as a positive contrast agent.

Centre for Nanotechnology Indian Institute of Technology Guwahati Guwahati 781039 Assam India

Department of Applied Chemistry S 5 National Institute of Technology Surat 395007 Gujarat India

Department of Chemistry Indian Institute of Technology Guwahati Guwahati 781039 Assam India

Department of Chemistry National Institute of Technology Durgapur 713209 West Bengal India

Department of Molecular Modelling Institute of Organic Chemistry and Biochemistry ASCR Flemingovo nám 2 CZ 166 10 Prague 6 Czech Republic

Citace poskytuje Crossref.org