Shape‐Adaptability and Redox‐Switching Properties of a Di‐Gold Metallotweezer

Abstract

The use of a carbazolyl‐connected di‐gold(I) metallotweezer for the encapsulation of several electron‐poor organic substrates, and a planar Au(III) complex containing a CNC pincer ligand, is described. The binding affinity of the receptor depends on the electron‐deficient character of the planar guest, with larger association constants found for the more electron‐poor guests. The X‐ray diffraction molecular structures of two host:guest adducts show that the host approaches its arms in order to facilitate the optimum interaction with the surface of the planar guests, in a clear example of an guest‐induced fit conformational arrangement. The electrochemical studies of the encapsulation of N,N’‐dimethyl‐naphthalenetetracarboxy diimide (NTCDI) show that the redox active guest is released from the receptor upon one electron reduction, thus constituting an example of redox‐switchable binding.

The New Di-Gold Metallotweezer Based on an Alkynylpyridine System

“…During the last few years, we reported a series of metallotweezers based on the use of two pyrene-bis-imidazolylidene-gold(I) arms bound with four different bis-alkynyl spacers (Scheme 1) [9][10][11][12][13][14][15]. These tweezers benefit from the tendency of Au(I) complexes to show linear geometry, and from the ability of the pyrene moieties to establish π-π-stacking interactions.…”

“…In contrast, the complex connected with the xanthenyl spacer B served as a metalloligand for metals such as Cu + , Ag + , and Tl + [11]. The complex with the carbazolyl spacer C was able to encapsulate planar aromatic guests by approaching its two polyaromatic arms, and thus showed an interesting example of a guest-induced-fit conformational arrangement [13,14]. Finally, the metallotweezer with the rigid dibenzoacridine spacer D allowed preparing a mechanically-interlocked dimer, which we named clippane, a term that we coined to refer to two-component MIMs formed by two entangled molecular tweezers [15].…”