Ground-state kinetics of bistable redox-active donor-acceptor mechanically interlocked molecules
Albert C Fahrenbach1, Carson J Bruns, Hao Li
1Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
Accounts of Chemical Research
|December 18, 2013
Summary
Chemists control artificial molecular machines by understanding the kinetics of bistable donor-acceptor mechanically interlocked molecules (MIMs). Controlling ground-state effects, spacer effects, and environment allows tuning MIMs for molecular machines.
Area of Science:
- Supramolecular Chemistry
- Materials Science
Background:
- Artificial molecular machines require precise control over kinetic processes.
- Bistable donor-acceptor mechanically interlocked molecules (MIMs), such as rotaxanes and catenanes, are promising prototypes.
- These MIMs exhibit controllable motions in response to redox stimuli.
Purpose of the Study:
- To rationalize the ground-state kinetic behavior of bistable donor-acceptor MIMs.
- To understand how to control the rate constants governing their isomeric state switching.
- To advance the design of artificial molecular machines capable of performing work.
Main Methods:
- Analysis of ground-state equilibrium between the ground-state co-conformation (GSCC) and metastable state co-conformation (MSCC).
- Investigation of factors influencing forward (kf) and backward (kb) rate constants.
- Examination of ground-state effects, spacer effects, and environmental influences on kinetics.
Main Results:
- Ground-state kinetics of bistable MIMs are governed by GSCC-MSCC equilibrium.
- Rate constants can be modulated over several orders of magnitude by managing key factors.
- Progress toward mechanostereoselective motion through strategic free energy barrier implementation.
Conclusions:
- Understanding and controlling MIM kinetics is crucial for developing functional artificial molecular machines.
- Key factors influencing kinetics offer pathways to tune molecular machine behavior.
- This work provides a foundation for designing sophisticated molecular devices.
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