Preparation, Characterization, and Biological Activity of Amides and Esters from 8-Hydroxyquinoline-2-Carboxylic Acid and Jeffamines ED® Or Poly(Ethylene Glycol)S

New macromolecular chelators were synthesized under mild conditions by reaction of 8-hydroxyquinoline-2-carboxylic acid (8Q2COOH) with polyethers having amino end-groups (Jeffamines ED®) or poly(ethylene glycol)s in the presence of dicyclohexylcarbodiimide and dimethylamino-pyridine. The prepared amides (8Q2CONH-POE) and esters (8Q2COO-POE) were characterized by SEC, DSC, IR, 1H and 13C NMR spectroscopy, and MALDI-TOF mass spectrometry. It was found that the polyethers had 8-hydroxy-2-quinolinyl end groups and formed complexes with Fe3+ ions. The obtained complexes were studied with IR spectroscopy and DSC. The plant tests showed that the Fe3+ complex of 8Q2CONH-POE2000 had high efficacy in the remedy of iron-deficient maize plants under hydroponic conditions.