Ultramacrocyclization in water via external templation

Condensing a dihydrazide and each of a series of cationic bisaldehyde compounds bearing polymethylene chains in weakly acidic water produces either a macrocycle in a [1 + 1] manner or its dimer namely a [2]catenane, or their mixture. The product distribution is determined by the length of the bisaldehydes. Addition of cucurbit[8]uril (CB[8]) drives the catenane/macrocycle equilibria to the side of macrocycles, by forming ring-in-ring complexes with the latter. When the polymethylene unit of the bisaldehyde is replaced with a more rigid p-xylene linker, its self-assembly with the dihydrazide leads to quantitative formation of a [2]catenane. Upon addition of CB[8], the [2]catenane is transformed into an ultra-large macrocycle condensed in a [2 + 2] manner, which is encircled by two CB[8] rings. The framework of this macrocycle contains one hundred and two atoms, whose synthesis would be a formidable task without the external template CB[8]. Removal of CB[8] with a competitive guest leads to recovery of the [2]catenane.

Construction of cucurbit[n]uril-based supramolecular frameworks via host-guest inclusion and functional properties thereof

Frameworks utilizing cucurbit[n]uril-based chemistry build on the rapid developments in the fields of metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), and supramolecular organic frameworks (SOFs), and as porous materials have found...

Cucurbit[n]uril-Based Supramolecular Frameworks Assembled through Outer-Surface Interactions

Porous materials, especially metal-organic frameworks, covalent organic frameworks, and supramolecular organic frameworks, are widely used in heterogeneous catalysis, adsorption, and ion exchange. Cucurbit[n]urils (Q[n]s) suitable building units for porous materials because they possess cavities with neutral electrostatic potential, portal carbonyls with negative electrostatic potential, and outer surfaces with positive electrostatic potential, which may result in the formation of Q[n]-based supramolecular frameworks (QSFs) assembled through the interaction of guests within Q[n]s, the coordination of Q[n]s with metal ions, and outer-surface interaction of Q[n]s (OSIQ). This review summarizes the various QSFs assembled via OSIQs. The QSFs can be classified as being assembled by 1) self-induced OSIQ, 2) anion-induced OSIQ, and 3) aromatic-induced OSIQ. The design and construction of QSFs with novel structures and specific functional properties may establish a new research direction in Q[n] chemistry.

Selective Identification of Phenylalanine Using Cucurbit[7,8]uril-Based Fluorescent Probes

The interactions of two host–guest inclusion complexes comprised of cucurbit[7]uril (Q[7]) and cucurbit[8]uril (Q[8]) with a derivative of toluidine blue O (TB) have been investigated using 1H NMR and fluorescence spectroscopy. The experimental results revealed that the Q[7] host interacts with a TB molecule to form a 1:1 inclusion complex and the Q[8] host interacts with two TB guest molecules to form a 1:2 inclusion complex. The inclusion of the TB guest molecule within the Q[7] host gave rise to significant fluorescence enhancement, whereas the inclusion of the TB guest molecule within the Q[8] host resulted in significant fluorescence quenching. Further recognition experiments involving a series of l-α-amino acids revealed that the TB@Q[7] inclusion fluorescence probe exhibits high selectivity for the recognition of phenylalanine via significant fluorescence quenching in an aqueous solution, whereas the TB@Q[8] inclusion fluorescence probe also exhibited high selectivity for phenylalanine recognition via fluorescence enhancement in an aqueous solution.

Glycoluril derived cucurbituril analogues and the emergence of the most recent example: tiarauril

Cucurbituril analogues can bear some of the chemical and physical characteristics of their parental origin and are derived wholly or in part from glycolurils (including homologues).

A CB[5] analogue based supramolecular polymer with AIE behaviors

An emissive supramolecular polymer was constructed by the self-assembly between a TPE quaternary ammonium salt and a cucurbit[5]uril analogue.

Graphene oxide based fluorescence sensor for cucurbit[7]uril

Rhodamine B (RhB) anchored reduced graphene oxide (RhBGO) offers a very sensitive and selective sensing potential for cucurbit[7]uril (CB[7]).