Construction of rotacatenanes using rotaxane and catenane frameworks

Abstract

The construction of novel mechanically interlocked structures has become a topic of great current interest due to the requirements of topology and their potential application in molecular machines and devices. Rotaxane and catenane as two basic topological frameworks can be used to construct the fused structures. In the current investigation, a class of novel ammonium backbones were synthesized. The ammonium group incorporated in the linear part of the molecule can be used for templating rotaxane formation while the macrocyclic part of the molecule can be used for templating catenane formation. Accordingly, they were subjected to dynamic covalent chemistry, resulting in a series of [n]rota[n]catenane structures (n = 2, 3, 4). In this process, the N-hetero crown ethers were installed on ammonium template sites of linear and macrocyclic components all at once by a template-directed clipping reaction. The results showed that these novel building blocks could be assembled with high efficiencies. Finally, this investigation provides a foundation for future studies aimed at constructing complicated integrated structures or polymers with multiple topological units.

Construction of a hetero pseudo[2]rota[2]catenane

“…In recent years, rotacatenanes have also 22 attracted increasing interests owing to the fact that it can lead to 23 different chemical structures with interesting functionalities 24 [21][22][23][24]. Motivated by the advancements of our previous works 25 [25][26][27][28][29][30][31][32][33][34][35], we recently reported a type of novel rotacatenane 26 topological structures, as shown in Scheme 1(A) [36]. In which, 27 the ammonium template was composed of two different types of 28 ammoniums.…”

“…As shown in Fig. 1, a [25][26][27][28][29][30][31][32][33][34][35][36]. Likewise, the process of clipping 161 reaction was recorded by 1 H NMR spectroscopy.…”

“…One type lay on the linear component of backbone 29 and the other type located on the macrocyclic component of 30 backbone. The guest was employed to perform the one-step 31 template-directed clipping reaction, affording the homo 32 [n]rota[n]catenane with novel topological structure [36]. It 33 prompts us to have an interest to construct the hetero 34 rotacatenane by use of different macrocyclic hosts.…”

“…Based on the above consideration, herein, 43 we designed and synthesized a novel ammonium backbone, which 44 contained three ammonium units. [36] as starting material was treated with 1,6-131 hexamethylenediamine 2 to afford the corresponding dynamic 132 imine, which was then reduced by NaBH 4 in the solution of THF and 133 MeOH to give the kinetically stable amine, and then the NH of free 134 amines was protected by Boc 2 O. Subsequently, the Boc-protected 135 macrocyclic compound 3 was obtained in 65% yields for three steps.…”

An Introduction to the Mechanical Bond

“…Another type of multicomponent architecture is that of the rotacatenane (Figure 1.28a, Section 4.3.1), first introduced 7 in 1999, which comprises a [2]catenane threaded by a molecular dumbbell. More recently, the term rotacatenane has been expanded to describe 304 larger architectures possessing both rotaxane and catenane moieties. A similar concept involves two dumbbells encircled by a single ring-an architecture (Figure 1.28e, Section 4.2.1.2) first created by Anderson.…”