1 Instituto de Ciencia Molecular, Universidad de Valencia, C/Catedrático José Beltrán Martínez 2, 46980 Paterna, Spain. salvador.blasco@uv.es enrique.garcia-es@uv.es.
2 University of Jyväskylä, Department of Chemistry, P.O. Box. 35, FI-40014, Finland.
A self-assembled metallobox from copper(ii) and two macrocycles containing 1H-pyrazole ligands has been prepared. The internal cavity of the box is able to selectively encapsulate a single chloride anion over any other halide anion.