A Modular Approach to Potential Synthetic Receptors with Large Surfaces Based on Crown[n]cavitands

A perspective to resorcinarene crowns

“…The lowest energy conformation of the structure has a C 2 symmetry due to the bis-bridging. The conformation of the cavitand core follows the crystal structure of 1b 13 with OCH 2 O bridges bent similarly toward the cavity. As expected, both of the crown ether bridges of cavitand 3b are more bent over the macrocyclic ring compared to the structure of 1b as the crown bridge moiety is six atoms shorter.…”

“…cavitands or tetramethoxyresorcinarenes. 11,12 Reinhoudt and co-workers 13 were the first to study the crown ether bridging with resorcinarenes. Instead of using resorcinarenes with free hydroxyl groups more rigid platform, tetrahydroxy resorcinarene cavitand (R=C 5 H 11 ), with four hydroxyl groups at the 2-position available for bridging, was chosen.…”

“…These properties are directly transferred to resorcinarene crown derivatives depending on the platform chosen as is evidenced by the crystal structure of 1,2-bridged crown [6]cavitand 1b (CCDC 101145): the cavitand core is a C 4v symmetrical crown conformation and the crown ether bridge, forming a separate extension to the cavity, adopts a slightly oval shape with an average diameter 35 of 5.68-7.24 Å (Figure 8). † 13 The cavity acts as a separate binding site for a molecule of ethanol situated in the middle of the cavity and the crown moiety binds two water molecules.…”

Crystal structure of 1,21,23,25-tetrapentyl-2,20:3,19-dimetheno- 1H,21H,23H,25H-bis[1,3]dioxocino[5,4-i:5',4'-i']benzo[1,2-d:5,4-d']-bis- [1,3]benzodioxocin-7,11,15,28-tetrol], C56H72O14

“…The crystal structure of thet etraiodoa nd tetrabromo cavitands have been described [7,8].B oth reveal acetonitrile co-crystallization in the "feet" but do not posses any hydrogen bonding. The crystal structure of 7,11-crown [6]-15,18-dihydroxy-1,21,23,25-tetrapentylcavitand was reported [9].The molecules form abilayer structure where thelast carbon atoms of thepentylchainsintergiditate betweenthe alkylchainsofthe next layer. Hydrogen bondsinvolving thefreehydroxylgroupsform links between the bilayers [9].…”

“…The crystal structure of 7,11-crown [6]-15,18-dihydroxy-1,21,23,25-tetrapentylcavitand was reported [9].The molecules form abilayer structure where thelast carbon atoms of thepentylchainsintergiditate betweenthe alkylchainsofthe next layer. Hydrogen bondsinvolving thefreehydroxylgroupsform links between the bilayers [9]. Herewereport the crystal structure with an ethylacetate guest molecule (Fig.).…”