Mn(II) based T1 and T2 potential MRI contrast agent appended with tryptamine: Recognition moiety for Aβ-plaques

We report the synthesis and characterization of manganese(II) complexes having pentadentate ligands L-1 (2,6-bis(1-(2-phenyl-2-(pyridin-2-yl)hydrazono)ethyl)pyridine), L-2 (methyl 2,6-bis((E)-1-(2-phenyl-2-(pyridin-2yl)hydrazono)ethy-Disonicotinate), L-3 (N-(2-(1H-indol-3-yl)ethyl)-2,6-bisaE)-1-(2-phenyl-2-(pyridin2yl) hydrazono)ethyl)isonicotiamide) and their application as dual contrast agents for simultaneous T-1 and T-2 weighted magnetic resonance imaging. Single crystal analysis of all the complexes [(MnL1)-L-II, (MnL2)-L-II and (MnL3)-L-II] confirm the formation of novel seven-coordinate manganese complexes with an inner sphere water and per chlorate ion. The Magnetic Resonance Imaging (MRI) contrast agent [MnL2] was further modified by incorporating tryptamine as a binding moiety specific to Amyloid Beta-fibrils (A beta-fibrils) in Alzhiemer's disease (AD) and it's in vitro evaluation for specific binding with All-fibrils indicated as a bio-marker of AD.