Structural design principles for self-assembled coordination polygons and polyhedra

Abstract

Strategies for the design of ligands that combine with metal ions to form high-symmetry coordination assemblies are reviewed. Evaluation of crystal structure evidence reveals that prior design approaches, based on the concept of complementary bonding vector angles, fail to predict the majority of known examples. After explaining the reasons for this failure, it is shown how an alternative approach, de novo structure-based design, provides a practical method that predicts a much wider range of component shapes encoded to direct the formation of such assemblies.

Topological landscapes of porous organic cages

“…29 These failures were due to either deviation from the ideal bonding vector through conformational flexibility or, more often, due to a concerted rotation about symmetry axes in the molecule. 29 If the lack of rigidity in MOP assemblies frustrates the simple geometric design of BBs, then this is even more problematic for organic cages that have less strongly directional bonding. In the successful cases of geometric BB design thus far, rigidity of the underlying BBs has assisted in this design simplification.…”

“…28 Hay has recently discussed design principles for metalorganic polygons and polyhedra (MOPs), emphasising that referring to these molecules by their shape can lead to multiple classifications for the same underlying topology, particularly for polyhedra that are face-directed, dependent on how you relate the metals and ligands to the vertices, edges or faces. 29 Instead,…”

Coordination-Driven Supramolecular Macromolecules via the Directional Bonding Approach

“…This is particularly apparent when considering the solid state structure of certain SCCs. Recently, a de novobased computational method was introduced by Young and Hay that addresses these distortions [3]. Although the authors present their computational approach in contrast to the directional bonding method, in reality it is a useful enhancement rather than a new approach entirely.…”

“…Likewise, the use of mononuclear metal nodes based on capped square or octahedral coordination geometries is not a rigorous requirement but rather one of convenience. When the requisite 90 angle can be encoded by different means, for instance by using two cis sites of a dinuclear paddlewheel motif, octanuclear squares may be obtained, such as those based on the Mo 2 (DArF) 3 + anion (DArF ¼ N,N 0 -diarylformamidinate) fragment bridged by ditopic dicarboxylate anions [31].…”

A M2L2 Redox-Active Metalla-Macrocycle Based on Electron-Rich 9-(1,3-Dithiol-2-ylidene)Fluorene

“…Since the pioneering example reported by Fujita [1], a plethora of ever more sophisticated metalla-rings and -cages constructed by coordination-driven self-assembly have been reported [2][3][4][5][6][7]. This methodology takes advantage of the labile character of the coordination bonds to produce high yields and single step thermodynamically stable architectures, with complex structures that would be challenging to reach through traditional organic chemistry.…”