Binding affinity of aniline-substituted dodecaborates to cyclodextrins

Area of Science:

• Supramolecular Chemistry
• Inorganic Chemistry
• Photochemistry

Background:

• Cyclodextrins are widely used host molecules in aqueous solutions.
• Hybrid organic-inorganic molecules offer unique properties for molecular recognition.
• Nitroaniline derivatives are known for their charge-transfer characteristics.

Purpose of the Study:

• To synthesize and characterize novel hybrid guest molecules for cyclodextrin recognition.
• To investigate the photophysical properties of these new hybrid molecules.
• To understand the influence of the dodecaborate cluster on guest molecule properties.

Main Methods:

• Synthesis of hybrid molecules linking nitroanilines to dodecahydrido-closo-dodecaborate (B12H12^2-).
• Study of guest-host interactions with cyclodextrins in aqueous solution.
• Spectroscopic analysis to determine photophysical properties and pKa values.

Main Results:

• Hybrid molecules demonstrated significant affinity for cyclodextrins.
• Unexpected, strong, low-energy charge-transfer bands were observed.
• The dodecaborate cluster increased the pKa of nitroanilines by 5.0–5.7 pH units.
• Deprotonated derivatives exhibited strong visible light absorption.

Conclusions:

• The dodecaborate cluster acts as an effective anchor group for cyclodextrin recognition.
• Hybrid nitroaniline-dodecaborate molecules possess unique and tunable photophysical properties.
• These findings open avenues for developing new functional materials based on hybrid supramolecular systems.