A new strategy for the synthesis of receptor molecules comprises the combination of medium-sized molecules to which functional groups for intermolecular interactions can be attached. Most efforts concern the functionalization of calixarenes, but other building blocks like cyclodextrins and octols are used as well. Selective mono-, 1,2-di, 1,3-di-, and tetraalkylation of calixarenes can be achieved by variation of the alkylation conditions. The calixarenes can be (selectively) functionalized at the “upper rim” by a variety of methods including ipso-nitration. Combination of the calixarenes with crown ethers to calixcrowns gave receptors with a high K+/Na+-selectivity and with terphenyls calixspherands were obtained that form kinetically stable complexes with Na+, K+ and Rb+. Bridging of calixarene with a salophene moiety gave a receptor for urea that can effectively transport urea through a supported liquid membrane. Calixarenes can be combined covalently to double and triple calixarenes and with selectively functionalized octols. When substituted with hydrogen bond donors and acceptors like 2-pyridone, calixarenes undergo self-association to larger aggregrates.
|NATO ASI Series C: Mathematical and Physical Sciences
|Kluwer Academic Publishers
|II NATO Science Forum on Supramolecular Chemistry 1991
|15/12/91 → 18/12/91