Journal of Inclusion Phenomena 5 (1987), 143-148. 143 9 1987 by D. Reidel Publishing Company. METAL-FREE MACROCYCLES VIA TEMPLATE METHOD: A STARTING POINT FOR SELECTIVE COMPLEXATION STUDIES. a * a,b c c D.E.Fenton, ~ B.P.Murphy, R.Price, P.A.Tasker and D.J.Winter a. a Department of Chemistry, The University, Sheffield, U.K. b School off Chemistry, Polytechnic of North London, London, U.K. c ICI plc, Organics Division, Blackley, Manchester, U.K. ABSTRACT. A new range of structurally-related macrocyclic ligands have been prepared and their potential as metal-ion discriminating agents examined. INTRODUCTION. The recognition and binding of metal ions by organic ligands has obvious implications for many aspects of chemistry and biochemistry. Valinomycin and the actin series of cyclic ionophores [1] are examples of how Nature has made use of the special properties of macrocycles to achieve discriminatory behaviour. The chemist, on the other hand, has through the years developed many 'classical' analytical reagents [2] which show reasonable specificity for particular ions, but their introduction has often resulted from chance observation rather than a systematically designed program. While much elegant work has been produced on the selective behaviour of the polyether macrocycles towards alkali and alkaline earth metal ions [3], studies involving the transition and base metal ions have been relatively scant. We report here a versatile route to a new range off structurally similar macrocycles as the first part of a longer term project aimed at the elucidation of the principles governing metal ion selectivity, DISCUSSION. There are basically two routes to the synthesis of macro- cyclic ligands. These are: (1) The in situ or template method, where the intervention of a metal ion directs the course of reaction towards cyclic rather than polymeric products. The product is usually a macrocyclic complex of the template metal used, and the macrocyclic cavity is normally of a size commensur- ate with the metal's ionic radius. While this technique has resulted in the isolation of many macrocycles which are not available by other means its main drawback is that demetallation to produce free ligand is not always possible; often the macrocycles prove unstable in the unto-ordinated state. * To whom correspondence should be addressed.