Supramolecular Chemistry of Anionic Dimers, Trimers, Tetramers, and Clusters

Two or more anions constrained in close proximity within a single pocket are found in a number of natural systems but are a less common motif in artificial systems. This review summarizes work on anion receptors capable of stabilizing anionic dimers, trimers, tetramers, and clusters in a well-defined fashion. These systems could provide insights into the fundamental chemistry of anion-anion interactions and provide a guide for understanding a number of biological and environmental processes in greater detail, as well as key tenants of relevance to supramolecular chemistry, extraction, transport, crystal engineering, and the like. The primary goal of this review is to provide a general introduction to multi-anion recognition chemistry for the benefit of supramolecular and nonsupramolecular chemists alike.