Stimuli-controlled self-assembly of diverse tubular aggregates from one single small monomer

Abstract

The design and synthesis of new stimuli-responsive hydrogen-bonding monomers that display a diversity of self-assembly pathways is of central importance in supramolecular chemistry. Here we describe the aggregation properties of a simple, intrinsically C2-symmetric enantiopure bicyclic cavity compound bearing a terminally unsubstituted ureidopyrimidinone fragment fused with a pyrrole moiety in different solvents and in the absence and presence of C60 and C70 guests. The tetrameric cyclic aggregate is selectively obtained in chlorinated solvents, where only part of the available hydrogen bonding sites are utilized, whereas in toluene or upon addition of C70 guests, further aggregation into tubular supramolecular polymers is achieved. The open-end cyclic assemblies rearrange into a closed-shell capsule upon introduction of C60 with an accompanied symmetry breaking of the monomer. Our study demonstrates that a C60 switch can be used to simultaneously control the topology and occupancy of tubular assemblies resulting from the aggregation of small monomers.

Chiral Nanotubes

“…Another recent example of guest-assisted host assembly of small molecules was reported by Shi et al, in which a stimuli-responsive H-bonding monomer changes its aggregation mode in response to different solvents or in the absence and presence of C 60 and C 70 guests [ 48 ].…”

Urea Derivatives as Functional Molecules: Supramolecular Capsules, Supramolecular Polymers, Supramolecular Gels, Artificial Hosts, and Catalysts

“…[61] Orentas and Wärnmark et al reported ureido group-substituted monomer 13 that forms variouss elf-assembled structures in response to stimuli ( Figure 11). [62] In chloroform,m onomer 13 forms ad iscretet ubular tetramer based on intermolecular hydrogen bonds. The tubular tetramer structure changes to at etrameric capsular structure by the addition of ag uest fullerene (C 60 ).…”

“… Stimuli‐responsive capsule‐tube isomerization. Reproduced with permission from reference [62], copyright 2017, Springer Nature.…”

Guidelines for the assembly of hydrogen-bonded macrocycles

“…3.1]nonane central blocks, to create chiral cavities with tuneable stability, size and function. [111][112][113][114][115] For instance, bis-UPy molecule 13 112 allowed the formation of a cyclic tetramer by quadruple H-bonding interactions between monomers (Fig. 11a).…”

“…11b). More recently, the authors published the study of related systems that can further aggregate into tubular supramolecular polymers by establishing orthogonal H-bonding interactions, 114,116 and in which the addition of C70 guests may induce such polymerization transition. 114 A recent study by Chamorro et al also disclosed evidence for synergic relationships between H-bonded macrocycles and carbon nanomaterials, in this case (6,5)SWCNTs (Single-Walled Carbon Nanotubes).…”