Cyanostar

The cyanostar structure is synthesized in a one-pot process among five equivalents of a benzaldehyde bearing a meta-cyanomethyl substituent. A series of Knoevenagel condensation reactions catalyzed by various bases stitches them together to make the C5-symmetric structure. == Anion binding ==

Cyanostar binds anions through hydrogen bonding from the C–H bonds, as the hydrogen has a positive electrostatic potential. It is the first binder to make use of cyanostilbene's electropositive CH groups. The CH bonds create an electropositive region in the center of the macrocycle, creating a binding pocket. Cyanostar strongly binds anions that usually can only be bound weakly. The increased binding arises from the formation of a 2:1 complex, with two cyanostars sandwiching the anion on each side. == Rotaxanes ==

Two cyanostars can be threaded onto a phosphate diester structure, forming a rotaxane. Because they have a high affinity for the central phosphate group only when it is in its anionic form, there is a substantial and reversible structural change in response to acid–base changes in solution. == References ==