Multilevel coordination-driven assembly for metallosupramolecules with hierarchical structures

Despite recent advances toward understanding metallosupramolecular platforms, structural classification remains a challenge because of the high multiplicity and diversity originating from the variety of three-dimensional binding modes of metal ions and multifunctional ligands. In this review, multilevel coordination-driven assembly and its potential implementation in the analysis of a variety of structurally complicated metallosupramolecules are demonstrated. The classification of coordination-driven structures with their respective hierarchy levels is summarized based on the ability of each structural unit to construct ordered molecular platforms. Multilevel assembly is composed of (i) primary, (ii) secondary, (iii) tertiary, or higher-order assembly. The coordination-driven binding modes should differ by levels in a complex. In particular, tertiary assembly involves the use of predefined, well-organized secondary supramolecules as basic modules to build discrete or polymeric structures. Using the suggested concept, coordination-driven metallosupramolecular platforms can be readily classified depending on their respective hierarchical structures. We expect that this simple analytical approach will provide researchers with a more effective understanding of coordination-driven assembly and facilitate the design of new complexes for specialized applications. (C) 2019 Elsevier B.V. All rights reserved.