Stereoelectronically-induced allosteric binding: shape complementarity promotes positive cooperativity in...

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry
• Materials Science

Background:

• Host-guest chemistry explores molecular recognition and self-assembly.
• Fullerenes, such as C60, are versatile carbon nanomaterials with unique electronic and structural properties.
• Corannulene derivatives offer tunable platforms for creating complex supramolecular structures.

Purpose of the Study:

• To investigate the formation and characteristics of a novel host-guest complex.
• To quantify the binding affinity and cooperativity between a specific corannulene derivative and C60.
• To elucidate the structural dynamics of C60 during the complexation process.

Main Methods:

• Synthesis of the 8-tert-butyl-6b2-azapenta-benzo[bc,ef,hi,kl,no]corannulene host molecule.
• Spectroscopic and computational methods to characterize the host-guest complex.
• Isothermal titration calorimetry (ITC) or similar techniques to determine binding constants and cooperativity.

Main Results:

• A 2:1 host-guest complex was successfully formed between the corannulene derivative (1) and C60.
• The complexation exhibited positive cooperativity with an alpha value of 2.56.
• High binding affinity was observed, with a combined equilibrium constant (K1 × K2) of 2.8 × 10^6 M^-2 at 25 °C.
• C60 demonstrated increasing shape complementarity with the host during binding.

Conclusions:

• The study successfully demonstrates the formation of a highly stable 2:1 host-guest complex.
• The observed positive cooperativity and high affinity highlight the intricate molecular recognition between the corannulene and C60.
• The dynamic shape adaptation of C60 suggests a sophisticated binding mechanism driven by steric and electronic factors.