Construction of multiferrocenyl metallacycles and metallacages via coordination-driven self-assembly: from structure to functions

Abstract

Recently, the construction of discrete multiferrocenyl organometallic structures via coordination-driven self-assembly has attracted considerable attention because of their interesting electrochemical properties and wide range of applications in the areas of organometallic chemistry, electrochemistry, and materials science. Coordination-driven self-assembly has proven to be a simple yet highly efficient approach for the preparation of various multiferrocenyl metallacycles and metallacages with predetermined shapes and sizes as well as the distribution and total number of ferrocenes. This review focuses on the recent progress in the construction of a variety of discrete multiferrocenyl metallacycles and metallacages via coordination-driven self-assembly. The characterization, the structure-related electrochemical properties, and the applications of these multiferrocenyl supramolecular architectures are also discussed.

Ferrocene‐ and Biferrocene‐Containing Macrocycles towards Single‐Molecule Electronics

“…These difficulties produce complex synthetic routes, low yields, or restrictions in the structures that can be formed. Methods to overcome this ring/chain equilibrium include pre‐organization and dynamic supramolecular assembly 6, 7, 8…”

Oligomeric ferrocene rings

“…Applying this methodology to 1,1′-diiodoferrocene (fc 1 I 2 ), 1,1′′′-diiodobiferrocene (fc 2 I 2 ) and 1,1′′′′′-diiodoterferrocene (fc 3 I 2 ) at high dilution, cyclo(1,1′-quinqueferrocene) (cyclo [5]; n = 5), cyclo(1,1′-sexiferrocene) (cyclo [6]; n = 6), cyclo(1,1′-septiferrocene) (cyclo [7]; n = 7) and cyclo(1,1′-noviferrocene) (cyclo [9]; n = 9) were fully or partially isolated for the first time (Fig. 1a).…”

“…Several families of organic cycles are known 2 , including cyclodextrins (n between 5 and 32), calixarenes (typically n = 4-6), cucubiturils (n = 5-8, 10) and pillararenes (n = 5-10), yet simple analogous series comprising unfunctionalized redox-active monomer units (n > 2) (for example, molecules comprising repeating metallocenes instead of repeating α-D-glucopyranosides) are practically unknown. With reference to functionalized examples, the anticipated unusual electrochemical, structural, magnetic and supramolecular properties of such materials will be related to their shape as well as the number, proximity and connectivity of their redox centres [3][4][5] . Having an internal cavity, they offer attractive opportunities as redox-active supramolecular hosts and may prove useful in molecular machinery (for example, functioning as molecular wheels) 6 .…”

“…Discovered in the early 1950s 11,12 , this complex is the prototypical metallocene and a ubiquitous redox-active moiety-a status facilitated by its ease of functionalization through classical aromatic reactivity as well as its remarkable air and thermal stability 13,14 . Many ferrocene-containing cyclic metallo-oligomers can be formed via dynamic supramolecular assembly 5 , but relatively few shape-persistent rings with covalent linkages between repeat units have been isolated. These include compounds with metallocene units linked by AX n (A = Si, X = Me; M = Fe; n = 2-7) 3,4 or CHR (R = H, Me; M = Fe, Ru; n = 2-5) groups [15][16][17] .…”

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

“…Beyond the synthetic challenge in preparing such objects, there is a strong interest in providing them with functionality, as encountered with recently described stimuli responsive rings and cages structures [13][14][15][16]. In this context, the preparation of redox-active metalla-rings/cages which allow a redox control over their overall charge appears relevant [17,18] and we described recently the first examples of electron-rich redox-active coordination cages capable of modulating their encapsulation properties through a redox stimulus [19,20].…”