Metalla‐Assembled Electron‐Rich Tweezers: Redox‐Controlled Guest Release Through Supramolecular Dimerization

Abstract

Developing methodologies for on‐demand control of the release of a molecular guest requires the rational design of stimuli‐responsive hosts with functional cavities. While a substantial number of responsive metallacages have already been described, the case of coordination‐tweezers has been less explored. Herein, we report the first example of a redox‐triggered guest release from a metalla‐assembled tweezer. This tweezer incorporates two redox‐active panels constructed from the electron‐rich 9‐(1,3‐dithiol‐2‐ylidene)fluorene unit that are facing each other. It dimerizes spontaneously in solution and the resulting interpenetrated supramolecular structure can dissociate in the presence of an electron‐poor planar unit, forming a 1:1 host–guest complex. This complex dissociates upon tweezer oxidation/dimerization, offering an original redox‐triggered molecular delivery pathway.

Oxidation triggers guest dissociation during reorganization of an FeII4L6twisted parallelogram

“…Metallocenes are furthermore redox-active, enabling potential stimuli-responsive behavior 42,[45][46][47][48][49][50][51][52][53] that may be used for different host-guest interactions, 45,47,54 such as redox-triggered guest ejection or structural reconguration. 55,56…”

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

“…In fact, redox processes can be used to control de binding strength between two interacting processes, and the term ‘redox‐switch binding’ is used in reference to the change of affinity between a substrate and a host receptor upon its oxidation or reduction [17d] . To our knowledge, the only example of an effective redox‐switchable metallo‐tweezer was reported by Sallé, Goeb and co‐workers recently [18] …”

Redox‐Active Supramolecular Heteroleptic M4L2L′2 Assemblies with Tunable Interior Binding Site

“…The incorporation of redox-active componentsi nto self-assembled assemblies has recently received attention, as it provides an entry to control chemicale vents [11] and may be relevant for sensing applications. [12] We recently demonstrated how the integration of two differentt ypes of redox-activel igandse nablest he reversible storage of up to 16 electrons in a Fujita-type 3D supramolecular assembly. [13] The dimensions Scheme1.Formation of homo-and heteroleptic supramolecular 2D assemblies, with the latter allowing for faciletuning of the inner cavity space by manipulation of length of the blue strut.…”

“…Only one example of self‐assembly of a heteroleptic PBI‐containing molecular assembly exists, to the best of our knowledge . Strikingly, the potential interplay between host‐guest chemistry properties and built‐in redox‐responsive character of molecular squares is relatively unexplored to date …”