Toward a new Molecular Recognition System and its related Interlocked Molecules

• Main Authors: Pin-nan Cheng, 鄭彬男
• Other Authors: 邱勝賢
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/18203731759938349592

碩士 === 國立臺灣大學 === 化學研究所 === 93 === Abstract We have synthesized a new molecular switch—based on a macrocycle–clip complex—whose switching behavior not only can be controlled through the use of either K+/[2,2,2]cryptand or NH4+/Et3N systems but also provides color changes that are visible to the naked eye; consequently, this system operates as a two-input NOR functioning molecular logic gate. We report a new host molecule in which one diethylene glycol chain (i.e., a loop possessing only three oxygen atoms) incorporated along with two phenolic aromatic rings is linked by a xylene spacer into a macroring. The design of the molecular structure of this macrocycle “amplifies” any potential [cation•••pi], [N+-H•••pi] and [N+C-H•••pi]interactions between the dibenzylammonium (DBA+) ion and the phenolic rings of the macrocycle; as such, these species display a very strong binding affinity in CD3NO2 (Ka = 15,000 M–1). The macroring also coordinates to bipyridinium ions in a [2]pseudorotaxane fashion, which makes it the smallest macrocycle (i.e., a 25-membered ring) known to complex both DBA+ and bipyridinium ions in solution. To confirm unambiguously that these pseudorotaxanes exist in solution, we synthesized their corresponding interlocked molecules, namely rotaxanes and catenanes.