New auxin analogs. Possible probes for auxin receptors

Based on structure-activity relationship studies, auxin analogs that can be covalently bound to a polymeric support are proposed. Molecular modeling s tudies were carried out by comparing different parameters of substituted ph enoxyacetic acids with their auxin activity. A good correlation of the acti vity with the size and shape of the HOMO orbital of the acids was found. Ac cordingly, analogs with a substituent in the 5 position of the aromatic rin g, capable to be bound to a polymeric matrix were synthesized and their aux in activity was evaluated with the wheat coleoptile elongation test. Compou nds with a hydroxymethyl- and with a carboxymethyloxy- substituent were act ive in this test. Their use as probes for the 2,4-D receptor is proposed.