Versatile cavitands for small molecules: the entropically driven ethanol selectivity

Size‐Selective and Reversible Encapsulation of Single Small Hydrocarbon Molecules by a Cavitand–Porphyrin Species

“…Upon exposure of CH 4 gas to a solution of 1 in CDCl 3 , a new proton signal appeared at δ =−7.19 ppm (Figure 1 b), which disappeared when Ar was bubbled into the solution 12. The large upfield shift (Δ δ =−7.34 ppm) from the signal of free methane ( δ =0.15 ppm) is rationalized by anisotropic effects arising from both the cavitand and porphyrin aromatic ring systems which are estimated to contribute to the upfield shift of the signal for the encapsulated molecule by δ =−3–−45b,c, 13 and δ =−4–−5 ppm,14 respectively. Thus, the signal at δ =−7.19 ppm is assigned to the protons of the encapsulated methane molecule.…”

Cambiarenes: Single‐Step Synthesis and Selective Zwitterion Binding of a Clip‐Shaped Macrocycle with a Redox‐Active Core

“…By harnessing electronic features like oxidation state, well‐defined macrocycles that can be switched between two different states have been generated. For example, Diederich and others have shown that the incorporation of quinone rings within or onto the macrocyclic backbone lead to changes in the electronic features of these supramolecular hosts. However, these structures require multi‐step syntheses and often lead to hosts that exhibit non‐specific guest binding.…”

Small Cavitands Specifically Binding a Water Molecule

“…The specific guest complexation by synthetic hosts has been a goal of molecular recognition studies. Various container hosts for small guest molecules such as MeOH, EtOH, CH 3 CN, CH 3 NO 2 , CH 3 CN, and CH 3 CHO have been reported. , Water is one of the most ubiquitous and most important molecules for biological systems. Recently, crystal structures of tetrameric and octameric water clusters have been observed in solid states.…”