Self-Assembly of Molecular Borromean Rings from Bimetallic Coordination Rectangles

In contrast to conventional stepwise synthesis of molecular Borromean rings, a self-assembly synthetic method which proceeds without the aid of a template has been developed. In the formation of molecular rectangles, by adjustment of the long-arm length of the rectangles, a series of size-dependent Borromean-link frameworks were constructed. Both the shortest length of two arms and the relative proportion of the length of the long arm to that of the short arm play a key role in the formation of Borromean rings. DFT calculations were used to provide theoretical support for the formation of discrete interlocked frameworks. A (Borro)mean business: For chemists, molecular Borromean rings represent a formidable synthetic challenge. Different from their stepwise synthesis with the aid of a well-known driving force, a self-assembly method associated with the formation of molecular rectangles is described. DFT calculations were used to provide theoretical support for the formation of these species.