Recent Advances in the Applications of Water‐soluble Resorcinarene‐based Deep Cavitands

Abstract

We review here the use of container molecules known as cavitands for performing organic reactions in water. Central to these endeavors are binding forces found in water, and among the strongest of these is the hydrophobic effect. We describe how the hydrophobic effect can be used to drive organic molecule guests into the confined space of cavitand hosts. Other forces participating in guest binding include cationÀ π interactions, chalcogen bonding and even hydrogen bonding to water involved in the host structure. The reactions of guests take advantage of their contortions in the limited space of the cavitands which enhance macrocyclic and site-selective processes. The cavitands are applied to the removal of organic pollutants from water and to the separation of isomeric guests. Progress is described on maneuvering the containers from stoichiometric participation to roles as catalysts.

Window[1]resorcin[3]arenes: A Novel Macrocycle Able to Self-Assemble to a Catalytically Active Hexameric Cage

“…While many new phenol-based macrocycles have been reported recently, − only very few have structural similarity to resorcin[4]­arene with a conformationally rigid bowl shape and unprotected phenol moieties. , However, no enlarged catalytically active capsule has been reported from these efforts as of yet. (2) While cavitands have been successfully utilized as reaction containers, ,,,− we considered it difficult to transfer the hydrogen bond network of capsule I , which seems essential for many reactions, − to a covalent cavitand structure. Thus, (3), the opening of the closed capsule to a cage-like structure seemed to be the best option.…”

Leveraging Torsional and Steric Strains: A Pre‐macrocyclization Strategy Enables Conformation‐Specific Fullerene Binding in m‐Cyclophanes

“…[13] Their preparation essentially involved additional post-macrocyclization steps; [10][11][12][13][14] that is, tying off the adjacent phenolic hydroxyl groups in 1 by various tethers. [10][11][12][13][14] These functionally-tweaked covalently-locked crowns were permanently rigid in solution and solid states. The conformationally arrested Cram's cavitands were later employed to construct carcerands, [2,15] hemicarcerands, [2,16] and molecular capsules.…”

“…To arrest conformational dynamism, covalently-locked pre-organized resorcinarene crowns (3, Figure 1B) were first made by Cram, [10] then by Rebek, [11] Diedrich, [12] and several others. [13] Their preparation essentially involved additional post-macrocyclization steps; [10][11][12][13][14] that is, tying off the adjacent phenolic hydroxyl groups in 1 by various tethers. [10][11][12][13][14] These functionally-tweaked covalently-locked crowns were permanently rigid in solution and solid states.…”

Thermally-induced atropisomerism promotes metal-organic cage construction

“… 1 , 8 – 10 , 19 – 26 , ox/reduction 27 , and/or temperature 2 , 3 , 12 , 28 , etc. Functional macrocycles with stimulus responses are frequently used for catalysis 4 , 22 , 29 , drug delivery 9 , 19 , 21 , 24 , substance separation 4 , 24 , 30 , adsorption 5 , 20 , and recognition 9 , 10 , 21 , 31 , 32 . The temperature response in particular is a typical occurrence in biological systems.…”