Complementarity and Preorganisation in the Assembly of Heterometallic–Organic Cages via the Metalloligand Approach—Recent Advances

Abstract

The design of new metallocage polyhedra towards pre-determined structures can offer both practical as well as intellectual challenges. In this mini-review we discuss a selection of recent examples in which the use of the metalloligand approach has been employed to overcome such challenges. An attractive feature of this approach is its stepwise nature that lends itself to the design and rational synthesis of heterometallic metal–organic cages, with the latter often associated with enhanced functionality.

Stepwise synthesis of heterotrimetallic FeII/PdII/AuI coordination cages

“…[1][2][3][4] However, the synthesis of cages containing three different metal ions is still challenging, and only a few examples have been reported in the literature. 1,4,5 Below, we describe the synthesis of a heterotrimetallic Pd II 6 Fe II 24 Au I 24 coordination cage. This cage was obtained by an Fe 2+ -templated polycondensation reaction, followed by regioselective complexation with Au + , and a final self-assembly step with Pd 2+ (Scheme 1).…”

Single-step synthesis of a heterometallic [Cu2PdL4]2+ lantern-type coordination cage

“…Firstly, the stepwise nature of these methods lengthens syntheses and total material costs. 17 Secondly, metal ions are restricted to pairs of an inert cation and a labile cation. Most homometallic lanterntype cages are constructed from square-planar Pd(II) ions, 18 with a smaller subset comprised of Cu(II) ions in dinuclear 'paddlewheel' subunits.…”

Investigating the Conformations of a Family of [M2L3]4+ Helicates Using Single Crystal X-ray Diffraction

“…Recently, our group has been interested in the metalloligand approach for constructing metallosupramolecular entities [ 12 , 13 , 14 ]. This method employs a coordination complex (or complexes) with secondary binding domains as building units for achieving larger self-assembled structures with both discrete [ 12 , 13 , 14 ] and continuous [ 15 , 16 ] architectures. The approach is to design ligands that form a complex with a primary metal while keeping additional (secondary) coordination donor sites free.…”

“…The approach is to design ligands that form a complex with a primary metal while keeping additional (secondary) coordination donor sites free. The primary metal acts to direct the coordination vectors of the secondary binding sites so that they are aligned for coordination with secondary metal centers in forming the final structure [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Using the metalloligand approach, it is thus usually possible to transfer, at least in part, the physical properties of the metalloligand units, such as luminescence and various magnetic behaviors, to the larger final architecture.…”