Dynamic combinatorial synthesis of a catenane based on donor–acceptor interactions in water

Abstract

A new type of neutral donor-acceptor [2]-catenane, containing both complementary units in the same ring was synthesized from a dynamic combinatorial library in water. The yield of the water soluble [2]-catenane is enhanced by increasing either buildingblock concentrations or ionic strength, or by the addition of an electron-rich template. NMR spectroscopy demonstrates that the template is intercalated between the 2 electron-deficient naphthalenediimide units of the catenane.dynamic combinatorial chemistry ͉ molecular recognition W e report here the spontaneous assembly of a donoracceptor (D-A) [2]-catenane from a dynamic combinatorial library (DCL) in water. Unusually, this is a D-A catenane that contains the electron-deficient and electron-rich aromatic moieties in the same ring. Owing to their complex topology and the resulting synthetic challenge, mechanically interlocked molecules such as catenanes have captivated chemists for a long time (1). With advances in the efficient templated synthesis of these interlocked structures, applications of these interesting molecules have been found in molecular electronic devices, such as switches, motors, color displays, and molecular memory (2-5).Conventional catenane synthesis relies on the use of noncovalent interactions to preorganize precursors in a suitable configuration that favors the formation of an interlocked structure, employing an irreversible, kinetically controlled chemical reaction as the final catenating step (for recent examples, see 6-9). The recent rise of dynamic covalent chemistry (10) using reversible chemical reactions under thermodynamic control has led to an increasing number of catenane syntheses that are either designed to lead to a particular structure (for recent examples, see 9, 11-19) or result from unpredictable dynamic combinatorial selection (20,21). The advantage of either of these dynamic strategies is the possibility of recycling un-interlocked components, hence increasing the yield of the desired structure.Interactions between electron-rich aromatics, such as dialkoxynaphthalene (DN) and tetrathiafulvalene (TTF), and electron deficient aromatics, like naphthalenediimide (NDI) and paraquat, have been extensively used in the preparation of catenanes (9,22,23). The vast majority of these catenane constructions rely on kinetically controlled reactions. Some examples of thermodynamically controlled syntheses of these structures include the neutral [2]-catenanes featuring zincpyridine coordination (24) and alkene metathesis as the ringclosing reactions (25). More recently, Stoddart and coworkers reported the iodide-catalyzed self-assembly of paraquat-based cationic D-A [2]-(16) and [3]-catenanes (14) from separate -donor and -acceptor rings using thermodynamically controlled nucleophilic substitution. Most of the examples of D-A catenane syntheses depend on a preformed, -rich crown ether ring containing electron-donor units, and the subsequent formation of new electron-deficient rings followed by catenation. Hence, the resulting catenanes...

Mechanostereochemistry and the mechanical bond

“…In addition, Sanders and co-workers have expanded the donor-acceptor toolkit, preparing MIMs with pyromellitic diimide and naphthalene diimide units as the electron-deficient components; these units have led to the synthesis of neutral donoracceptor MIMs (Hamilton et al 1998). This very same research group have described (Au-Yeung et al 2009) more recently the preparation of various catenanes (Cougnon et al 2011(Cougnon et al , 2012) based on neutral building blocks by employing dynamic combinatorial protocols in aqueous media. By mixing compounds containing electron-poor and electron-rich aromatic rings with appended thiol functions, a dynamic library of interconverting macrocycles and catenanes is generated through reversible oxidative dithiol coupling reactions where conditions can be altered to favour the self-assembly of the desired MIM(s).…”

Strategien und Taktiken für die metallgesteuerte Synthese von Rotaxanen, Knoten, Catenanen und Verschlingungen höherer Ordnung

“…[124] [3]- [125] und [5]Rotaxane [126] hçherer Ordnung wurden ebenfalls durch Verschließen von Cu I dpp-Pseudorotaxanen mit Porphyringruppen synthetisiert. [127] Alternative Methoden des kovalenten Einfangs wurden auch als Zugang zu verschlungenen Templatstrukturen mit nur einem Cu I -Ion verwendet.…”

“…Sauvage und Mitarbeiter berichteten über die Weiterentwicklung ihres [4]Rotaxans 51-Cu I (Abbildung 8) durch die Bindung von Tetrathiafulvalen zwischen den PorphyrinEbenen. [343] Unter Verwendung des klassischen dpp-Makrocyclus 19 (Schema 5) und einer Achse mit sowohl zwei-als auch dreizähnigen Domänen gelang die Herstellung eines linearen [5]Rotaxans durch eine modulare Strategie. [156] Ebenfalls berichtet wurde über die verwandten [2]-, [3]-und [4]Rotaxane, die die gleiche Achse, aber unterschiedliche Zahlen aufgefädelter Makrocyclen enthalten, und die das Potenzial haben, als Multiring-Shuttles zu agieren.…”

Dynamic Covalent Synthesis of Donor–Acceptor Interlocked Architectures in Solution and at the Solution:Surface Interface

“…[11,13,14] The energetic bias towards interlocked architectures renders dynamic covalent chemistry-the chemistry of thermodynamically controlled bond formation-a powerful tool in the creation of mechanical bonds. [15] Numerous reversible covalent bond forming reactions, including imine, acetal, hydrazone, and ester formation as well as Aldol, Diels-Alder, Michael, nucleophilic substitution, and olefin metathesis reactions, have been used to prepare mechanically interlocked compounds in high yields; [12,14,[16][17][18][19][20] however, the work described herein exploits disulfide exchange in the dynamic covalent assembly of catenanes and rotaxanes. Research undertaken by Sanders et al have demonstrated the success of such an approach by synthesizing a range of electron-rich 1,5-dialkoxynaphthalene and electron-deficient 1,4,5,8-naphthalene tetracarboxylic diimide catenanes [16,18,21,22] and even a trefoil knot [7] via disulfide exchange from simple building blocks.…”