Inspite of advances, critiques and counters critiques on the mode of action of plant auxins, the controversy on this issue still hangs on. Sawhney, Chauhan et.al. (1-8),contributed greatly knowledge at the metal affinity to plant auxin in solution and solid state. The subject matter, this paper embodies, is concerned with the solution and solid state chemistry of the interaction of some of the plant auxins: indole- 3- butyric acid (IBA), indole- 3 -propionic acid(IPA) and 1- napphthalene acetic acid(NAA), and some of the lanthanide series elements:M(III), etc. have been taken as model studies under thermodynamic conditions.. This is an attempt to carry out an equilibrium analysis of Gd(III) -IBA, Gd(III) -IPA and Gd(III) -NAA systems at constant ionic strength and at infinite dilution, to give an explanation of the stability and thermodynamics of these systems.

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Keywords: Gd(III), Critiques, Controversy, Auxin, Thermodynamics, Collusion, Carboxylic Group.