ORGN 699 |
| The area of supramolecular molecular recognition chemistry has drawn considerable attentions recently and consequently many receptor models for cation or anion binding have been synthesized and studied. Concomitant complexation of cation and anionic guests by single receptor molecule are particularly important due to their environmental and biological implications. The ion-pair recognition is usually based on the hydrogen bonding, cationic, coordinative interaction with anionic guests and macrocyclic multi-oxo or aza containing motif for cationic guests. With these regards, we have designed and synthesized tightly coupled calix[4]pyrrole-calix[4]crown-5 conjugates as novel models for ion-pair/salt recognition. The concept of design is based on the fact that the combination of better neutral anion binding properties of calix[4]pyrrole and strong cation binding properties of calix[4]crown-5 would exhibit enhanced affinity for guest ion-pair and possibly will show size recognition properties. The synthesis of target host moleculs have accomplished by synthetic strategy as those of the strapped calix[4]pyrroles. The preliminary binding studies and spectroscopic evidences indicated that the cavity of the host molecule was occupied by one NaOH. The cation replacement studies indicated that the bound sodium ion can be replaced with potassium ion. Smaller size anion such as fluoride anion also can be strongly bound inside the cavity. The detailed ion-pair recognition properties and anion selectivities of the synthesized receptors will be presented. |
|
Asymmetric Reactions, Combinatorial Chemistry, Molecular Recognition and Self-Assembly, Proteins, Peptides, Amino Acids and Enzyme Inhibitors
8:00 PM-10:00 PM, Wednesday, March 28, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Organic Chemistry |