Cooperativity in molecular recognition of feet-to-feet-connected biscavitands

Autor: Takeharu Haino
Rok vydání: 2023
Předmět:
Zdroj: Pure and Applied Chemistry. 95:343-352
ISSN: 1365-3075
0033-4545
Popis: Octaphosphonate biscavitand and self-folding deep biscavitand show strong positive and negative cooperativity, respectively. The mechanism of the cooperativity is discussed in terms of thermodynamic parameters and the detailed structure of the host-guest complexes. The two cavitand units of both biscavitands are tightly connected via four butylene linkers; thus, they are conformationally coupled, with the first guest binding information transferred to the resting-state cavities. This preorganization modulates the successive guest binding process in strong positive and negative cooperative manners, even though they display structural similarity. The first guest complexation always preorganizes the resting-state cavities where an existing water cluster and a toluene molecule are enthalpically stabilized. Successive guest complexation competes with the water cluster or a toluene molecule, reducing enthalpy gains. However, the desolvation upon successive guest binding processes liberate the solvents within the resting-state cavities. The water cluster is composed of 12 water molecules that are released upon successive guest complexation, resulting in a large entropy benefit. In contrast, toluene desolvation results in a limited entropy benefit. The difference in entropy benefits directs the strong positive or negative cooperativity of the structurally similar biscavitands.
Databáze: OpenAIRE
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