To make actual devices, crown ether
pores would need to be fabricated reliably in physical samples of graphene or other materials that are just a few atoms thick and conduct electricity.
It is well known that the extractability of metal ions with macrocylic reagents such as crown ether
and cryptand is governed by the stability of the metal complexes .
Four monomeric building blocks equipped with one crown ether
and one secondary ammonium ion are synthesized and studied with respect to their ability to form daisy chain dimers.
Du et al., "A new method for fast intercalation of bulk crown ether
guest into LDH," Journal of Colloid and Interface Science, vol.
The zinc acetate dihydrate Zn[(C[H.sub.3]COO).sub.2]2[H.sub.2]O, 25% ammonia (N[H.sub.3]), ferric nitrate hexahydrate [(Fe(N[O.sub.3]).sub.3] x 6[H.sub.2]O, potassium nitrate (KN[O.sub.3]), tetrahydrofuran (THF), selective iron (III) ionophore trans-dinitro-dibenzo-18-6 crown ether
, polyvinyl chloride (PVC), 2-nitopentylphenyl ether as plasticizer (NPPE), tetrabutyl ammonium tetraphenylborate (TBATPB) as conductivity increaser were purchased from Sigma Aldrich, Sweden.
The inorganic clay ([Na.sup.+], [K.sup.+]) was dispersed in distilled water (~1 / 100, by weight) by stirring overnight in a beaker; then a 1 ~3 % by volume solution of crown ether
in acetone (~150 mmol/ 100 g, crown ether/clay) was added slowly to the suspension.
Photo: A crown ether
unfolds to grab a potassium ion.
To mimic the active site, macrocyclic compounds such as cyclodextrins , crown ether
, cyclophanes and calixarenes , each having an inclusion cavity as a basic skeleton of potent artificial monooxygenase, were usually employed.
Cyclodextrins and crown ethers
are widely used as adsorbent or ligands in these methods.
For instance, Pearson and Hwang were pioneers in the field and reported many TAPD-based chemosensors formed by crown ethers
as ionophore sites and phenylenediamine moiety as a transducer capable of detection of alkaline or alkaline earth cations .
Candidate binding groups include aliphatic quaternary amines, organophosphate complexing agents, chelating agents, crown ethers
The two authors hope to guide readers to see "...their inherent beauty and aesthetic appeal." Coverage encompasses cyclophnes; crown ethers
, cryptands, and other compounds; calixarenes; heterocalixaresn and calixnaphthalenes; cyclodextrins; cyclotriveratylenes and cryptophnes; cucurbiturils; rotaxanes and catemanes; and other supramolecular systems, molecular motors, machines, and nanotechnological applications.