Stacking Interactions Induced Selective Conformation of Discrete Aromatic Arrays and Borromean Rings

Abstract

Herein, we describe how to utilize stacking interactions to achieve selective supramolecular transformation and molecular Borromean rings (BRs). By using a dinuclear naphthalenediimide (NDI)-based Cp*Rh acceptor and linear bipyridyl ligands, organometallic rectangles featuring dynamic behavior have been constructed. Unique discrete aromatic stacking arrays were formed by inducing pyrene units as guest molecules. The topology of the BRs was realized by the use of a strategically chosen ligand which was capable of participating in D−A interactions and hydrogen bonding, as evidenced from single-crystal X-ray analysis and computational studies. These self-assembly processes underline the advantages of dynamic bonding and π−π stacking interactions, and serve to illustrate a new approach to generating structurally and topologically nontrivial supramolecular architectures.

Donor–Acceptor [2]‐ and [3]Catenanes Assembled from Versatile Pre‐Organized Cp*Rh/Ir‐Directed Pseudorotaxane Tectons

“…Note that in the structure one of the binuclear tectons adopts a cis conformation whereas the other is trans . This is abnormal and different from the reported solid‐state structure of the bare metalla‐rectangle 4 b′ . Besides, no biasing interaction was observed to restrain the conformations and orientations of the binuclear tectons.…”

“…Recently, our group reported the facile synthesis of a binuclear Cp*Rh‐based tecton featuring one naphthalenediimide (NDI) unit . The binuclear complex exhibits two dynamic conformations: the cis and trans form.…”

“…Encouraged by the successful preparation of [2]catenanes, we next attempted to synthesize [3]catenanes. 4,4‐Bipyridine, a longer linear linker, was chosen as its length—11.3 Å, estimated as the resulting M⋅⋅⋅M separation—matches that required for a quadruple stack (including both sides of the metalla‐rectangles) according to previous studies . The [3]catenanes 4 a and 4 b were thereby obtained by following a procedure similar to that previously used to obtain [2]catenanes (Yields: 4 a : 88 %, 4 b : 78 %).…”

Dynamic Interconversion between Solomon Link and Trapezoidal Metallacycle Ensembles Accompanying Conformational Change of the Linker

“…[Cp*RhCl 2 ] 2 (Cp* = h 5 -pentamethylcyclopentadienyl), [16] the ligand N,N'-bis(4-pyridylmethyl)-1,4,5,8-naphthalenetetracarboxydiimide (L), [17] and 2,7-dihydroxybenzo[lmn] [3,8]phenanthroline-1,3,6,8-(2H,7H)-tetraone (DHNDI) [18] were prepared according to literature methods. [Cp*RhCl 2 ] 2 (Cp* = h 5 -pentamethylcyclopentadienyl), [16] the ligand N,N'-bis(4-pyridylmethyl)-1,4,5,8-naphthalenetetracarboxydiimide (L), [17] and 2,7-dihydroxybenzo[lmn] [3,8]phenanthroline-1,3,6,8-(2H,7H)-tetraone (DHNDI) [18] were prepared according to literature methods.…”

Discrete Supramolecular Stacks Based on Multinuclear Tweezer‐Type Rhodium Complexes

“…Firstly, the rigid building block [Cp*MCl] 2 B1 (M=Rh, Ir) (Scheme ), with a metal–metal separation of about. 7 Å was selected . With the different polycyclic proligands employed, tetranuclear rectangle or duplex metallotweezer structures were assembled, in which the proligands underwent bilateral ( L1 , L2 ) or unilateral ( L3 , L4 ) C−H activation.…”