Equilibrating dynamic [2]rotaxanes.
Upon mixing and dehydration, 2,6-diformylpyridine and 2,2'-oxybis(ethylamine) form a dynamic combinatorial library of at least nine members. Through hydrogen bonding and other intermolecular interactions, templating dumbbell molecules select one macrocyclic member of the library, at the expense of all the others, to create [2]rotaxanes. These rotaxanes, however, retain the dynamic character of the library, since a diformylpyridine analogue can exchange with the macrocyclic component in solution. In addition, crystallization of the mixture surprisingly furnishes only the [24]crown-8-like macrocycle on its own--evidence of a kinetic selection process occurring between phase transitions.
California NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095-1569, USA.
Philip C
PC
Haussmann
Saeed I
SI
Khan
J Fraser
JF
Stoddart