A novel two-dimensional homochiral manganese(II)-carboxylate coordination framework exhibiting field-induced spin-flop transition

The reaction of a unique asymmetric bridging ligand 4-(4- carboxyphenylamino)-3,5-dinitrobenzoic acid (H₂cpdba), MnCl ₂·4H₂O and NaOH yields a novel two-dimensional coordination polymer, {[Mn(cpdba)(H₂O)₃]·H ₂O}_n (1) containing homochiral helical Mn(II) chains linked by syn-anti carboxylate bridges, in which the chirality of a stereochemically labile amine core of a carboxylate ligand can be "locked" by the coordination bonds and consequently transferred throughout the entire coordination framework. Magnetic susceptibility measurements reveal weak antiferromagnetic interactions between adjacent Mn(II) ions, with a field-induced spin-flop magnetic transition occurring at ca. 2.6 T at 2 K.