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Molecular Pumps that drives a system away from equilibrium

Cheng, Chuyang and Li, Hao and Liu, Weiguang and McGonigal, Paul R. and Vermeulen, Nicolaas A. and Frasconi, Marco and Ke, Chenfeng and Goddard, William A., III and Stoddart, J. F. (2013) Molecular Pumps that drives a system away from equilibrium. In: 246th ACS National Meeting & Exposition, September 8-12, 2013, Indianapolis, IN.

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A pressing goal for contemporary science is to build artificial mol. systems that can perform useful work. Here we report a 'mol. pump' system that processes chem. energy (redox) to drive a macrocycle away from equil., from a low energy to a high energy state. A series of mol. rods were synthesized contg. 3,5- dimethylpyridinium (Py +) and 4,4'-bipyridinium (BIPY 2+) units connected to a bulky steric stopper by chains of different lengths. Cyclobis(paraquat-p-phenylene) (CBPQT 4+) is repelled by the Py + and BIPY 2+ initially; however, upon redn. with activated zinc dust, Coulombic repulsion between Py + and CBPQT 2(+•) dramatically decreases and a thermodynamically stable trisradical complex BIPY +•I CBPQT 2(+•) is formed within seconds. Tris(4-bromophenyl)aminium hexachloridoantimonate (Magic Blue) was used to oxidize the radical cation rapidly to the fully oxidized state. The electrostatic Py + barrier is recovered, causing the CBPQT 4+ ring to shuttle on to the glycol/alkyl chain, for which it has little affinity. Dethreading from this high energy, metastable [2]rotaxane state occurs slowly due to Coulombic repulsion between CBPQT 4+ and Py +/BIPY 2+. Exptl. results and DFT calcns. show that the mol. pump can raise the potential energy of CBPQT 4+ up to 13 kcal/mol with an efficiency up to 8%.

Item Type:Conference or Workshop Item (Paper)
Related URLs:
URLURL TypeDescription Website
Cheng, Chuyang0000-0002-3834-0479
Liu, Weiguang0000-0002-6633-7795
McGonigal, Paul R.0000-0002-8538-7579
Vermeulen, Nicolaas A.0000-0003-1825-4474
Frasconi, Marco0000-0003-2010-175X
Ke, Chenfeng0000-0002-4689-8923
Goddard, William A., III0000-0003-0097-5716
Stoddart, J. F.0000-0003-3161-3697
Additional Information:© 2013 American Chemical Society.
Record Number:CaltechAUTHORS:20140213-133442920
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43816
Deposited By: Tony Diaz
Deposited On:25 Mar 2014 17:35
Last Modified:03 Oct 2019 06:11

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