Precise Control of Noncovalent Dimerization via Cucurbit[n]uril-Based Host-Guest Complexation.

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Photochemistry

Background:

• Fluorenone derivatives are known for their photophysical properties.
• Controlling the aggregation state of organic molecules is crucial for tuning their optical properties.
• Supramolecular hosts like cucurbit[n]urils offer precise control over guest molecule interactions.

Purpose of the Study:

• To investigate the complexation behavior between cucurbit[n]urils (n=7, 8, 10) and a fluorenone derivative.
• To demonstrate the precise switching of fluorenone aggregation states through host-guest interactions.
• To develop multicolor luminescent materials in aqueous solution using this supramolecular approach.

Main Methods:

• Synthesis of a fluorenone derivative.
• Complexation studies using different sizes of cucurbit[n]urils (CB[7], CB[8], CB[10]).
• Spectroscopic analysis (UV-Vis absorption, fluorescence) to determine aggregation states and luminescence properties.
• Investigation of binding modes and their effect on aggregation.

Main Results:

• Complexation with cucurbit[n]urils precisely switched fluorenone aggregation from J-aggregates to monomer, H-dimer, and separated "H-dimer" states.
• The size of the cucurbit[n]uril host influenced the resulting aggregation state and binding mode.
• Multicolor luminescence was achieved in aqueous solution by controlling the aggregation state of the fluorenone guest.

Conclusions:

• Cucurbit[n]urils are effective supramolecular hosts for controlling the aggregation and luminescence of fluorenone derivatives.
• This host-guest system provides a versatile platform for designing tunable multicolor luminescent materials.
• The findings highlight the potential of supramolecular chemistry in developing advanced functional materials for aqueous applications.