A new lithium receptor based on the combination of the [11] macrocyclic core and two catecholunitawaadesignedand prepared.'Iltebindingabilityof the Iigarrdtowardsboronandlithiumwas demonstratedin solutionby NMR and in the solid stuteby an X-ray analysisof the Iithiumboroeryptate. 01997 Elsevier Science Ltd.
Due to the role played by lithium in science, medicine and technology,l the design of Li-selective completing agent is still an active area of research. The complexation of lithium by a variety of synthetic receptor molecules has been investigated.2 Among many structural features screened, cryptandss and spherandsq appeared to be the most appropriate and selective receptors for lithium. Based on structural aspects of boromycins and aplasmomycin6, natural antibiotics bearing a spiroborate group, and of cryptands, we have designed a new family of artificial receptors for alkaline metal cations.7-10The early design of boroeryptrmd was based on the double functionalisation, at both nitrogen centres, of the [221 macroeyclic core by two catechol units7 leading thus to the receptor molecule 1. The simultaneous binding of boron and alkaline metalg.gas well as