Twisted Cucurbit[n]urils.

Area of Science:

• Supramolecular Chemistry
• Macrocyclic Chemistry
• Crystal Engineering

Background:

• Cucurbiturils (Q[n]) are a class of macrocyclic hosts with a unique structure and wide applications.
• The synthesis of larger Q[n] derivatives expands the possibilities for host-guest chemistry.

Purpose of the Study:

• To synthesize and characterize two new twisted cucurbiturils: cucurbit[13]uril (tQ[13]) and cucurbit[15]uril (tQ[15]).
• To determine the structural features and host-guest properties of these novel macrocycles.

Main Methods:

• Synthesis and separation of tQ[13] and tQ[15].
• Structural characterization using NMR spectroscopy and MALDI-TOF mass spectrometry.
• X-ray diffraction analysis of complexed structures: {Dy(H2O)4Cd(H2O)4tQ[13]}·2.5[CdCl4]·65H2O and {Cd0.5(H2O)2tQ[15]}·[CdCl4]·47H2O.
• Preliminary host-guest behavior investigation using NMR studies.

Main Results:

• Successful synthesis and isolation of tQ[13] and tQ[15].
• tQ[15] represents the largest cucurbit[n]uril reported to date.
• X-ray diffraction studies revealed that these large twisted cucurbiturils possess distinct central and two side cavities.
• Initial NMR studies provided insights into the host-guest interactions of the new systems.

Conclusions:

• The successful synthesis of tQ[13] and tQ[15] broadens the scope of cucurbituril chemistry.
• The unique multi-cavity structure of these large macrocycles offers new potential for molecular recognition and encapsulation.
• Further investigations into the host-guest properties are warranted to explore their applications.