Small Cavitands Specifically Binding a Water Molecule

Abstract

[structure: see text] Three new C(2v) cavitands based on resorcin[4]arene bind water specifically at low temperature in CD(2)Cl(2) or CDCl(3) due to their complementarity to water as well as the solvophobic interaction. The averaged DeltaH(o) and DeltaS(o) values are -2.3 kcal mol(-1) and -128 cal mol(-1) K(-1), which gave the averaged -DeltaG(o) of 1.9 kcal mol(-1) at -50 degrees C in water saturated CD(2)Cl(2).

Supramolecular Chemistry in Water

“…The cavity of the classical cavitand 53 is much smaller than that of cucurbituril and the metal–organic cages described by Fujita and co‐workers (see Section 8.3). It can accommodate only one molecule of water at −50 °C in water‐saturated CD 2 Cl 2 ( K a ≈70 M −1 ) 140…”

Self‐Discriminating Self‐Assembly of Dinuclear Heterochiral Rhombs from Tröger’s Base Derived Bis(pyridyl) Ligands

“…Der Hohlraum der klassischen Cavitanden 53 ist sehr viel kleiner als derjenige in Cucurbituril oder den metall‐organischen Käfigen von Fujita (siehe Abschnitt 8.3), weshalb sie bei −50 °C in wassergesättigtem CD 2 Cl 2 nur ein Wassermolekül aufnehmen können ( K a ≈70 M −1 ) 140…”

Kinetics and Solvent-Dependent Thermodynamics of Water Capture by a Fullerene-Based Hydrophobic Nanocavity

“…The thermodynamics properties of this reaction resemble those for both cavitand porphyrins that spontaneously encapsulate dissolved CH 4 , as well as hydrogen-bonding cavitands that bind water from organic solution at low temperatures (−50 °C) . However, in both cases the change in free energy is lower for the formation of H 2 O@ 1 , possibly due to the polar nature of H 2 O.…”

“…A wide variety of systems have been developed to trap small amounts of water molecule(s). Successful capsules include oligomer or polymer helices, some cavitands, and chemically opened fullerenes. − The last fullerenes are generally described as open-cage fullerenes. − The inner sphere of the most abundant fullerene, C 60 , has been estimated to be approximately 3.5 Å in diameter, similar to common desiccants, 3- or 4-Å molecular sieves. To access the closed interior of a fullerene, carbon−carbon bonds of the ‘cage’ must be cleaved by organic reactions designed to afford either resealable or permanent openings.…”