ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Molecular Motor

1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Molecular Motor Prepared by: Joseph Thomas Dept. of Electrical and Computer Engineering Utah State University E: (435)757-7962 ; T: (435)797-; F: (435)797-3054 (ECE Dept.) 3/6/2009

2. Outline • Reference list • To probe further • Major applications • Basic working principle illustrated • A typical sample configuration in application (application notes) • Limitations ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

3. Reference list • A Reversible, Unidirectional Molecular Rotary Motor Driven by Chemical EnergyStephen P. Fletcher, Frédéric Dumur, Michael M. Pollard, and Ben L. Feringa (7 October 2005) Science310 (5745) • Nanoscale Rotary Motors Driven by Electron Tunneling Boyang Wang, Lela Vukovic, and Petr Kral, Phys. Rev. Lett. 101, 186808 (2008) • Chemically Tunable Nanoscale Propellers of Liquids Boyang Wang and Petr Kral, Phys. Rev. Lett. 98, 266102 (2007) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

4. To explore further (survival pointers of web references etc) • http://www.chemistry.illinois.edu/research/organic/seminar_extracts/2002_2003/Quinn.pdf • http://www.sciencemag.org/cgi/content/abstract/310/5745/80 • http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JCPSA6000123000018184702000001&idtype=cvips&gifs=yes ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. Major applications • The assembly of a molecular propeller and a molecular motor can form a nanoscale machine that can pump fluids or perform locomotion. Future applications of these nanosystems range from novel analytical tools in physics and chemistry, drug delivery and gene therapy in biology and medicine, advanced nanofluidic lab-on-a-chip techniques, to tiny robots performing various activities at the nanoscale or microscale. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. Basic working principle illustrated Chemically driven rotary molecular motors ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. Basic working principle illustrated Chemically driven rotary molecular motors The system is made up from a three-bladed triptycene rotor and a helicene, and is capable of performing a unidirectional 120° rotation.This rotation takes place in five steps. First, the amine group present on the triptycene moiety is converted to an isocyanate group by condensation with a phosgene molecule (a). Thermal or spontaneous rotation around the central bond then brings the isocyanate group in proximity of the hydroxyl group located on the helicene moiety (b), thereby allowing these two groups to react with each other (c). ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Basic working principle illustrated Chemically driven rotary molecular motors This reaction irreversibly traps the system as a strained cyclicurethane that is higher in energy and thus energetically closer to the rotational energy barrier than the original state. Further rotation of the triptycene moiety therefore requires only a relatively small amount of thermal activation in order to overcome this barrier, thereby releasing the strain (d). Finally, cleavage of the urethane group restores the amine and alcoholfunctionalities of the molecule (e). ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. Basic working principle illustrated Light-driven rotary molecular motors ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

10. Basic working principle illustrated Light-driven rotary molecular motors The 360° molecular motor system consists of a bis-helicene connected by an alkene double bond displaying axial chirality and having two stereocenters.One cycle of unidirectional rotation takes 4 reaction steps. The first step is a low temperature endothermic photoisomerization of the trans (P,P) isomer 1 to the cis (M,M) 2 where P stands for the right-handed helix and M for the left-handed helix. In this process, the two axial methyl groups are converted into two less sterically favorable equatorial methyl groups. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

11. Basic working principle illustrated Light-driven rotary molecular motors By increasing the temperature to 20 °C these methyl groups convert back exothermally to the (P,P) cis axial groups (3) in a helix inversion. Because the axial isomer is more stable than the equatorial isomer, reverse rotation is blocked. A second photoisomerization converts (P,P) cis 3 into (M,M) trans 4, again with accompanying formation of sterically unfavorable equatorial methyl groups. A thermal isomerization process at 60 °C closes the 360° cycle back to the axial positions. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. Basic working principle illustrated Light-driven rotary molecular motors ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

13. Basic working principle illustrated Light-driven rotary molecular motors Another example of synthetic chemically driven rotary molecular motor that has been reported in literature make use of the stereoselective ring opening of a racemic biaryl lactone by the use of chiral reagents, which results in a directed 90° rotation of one aryl with respect to the other aryl. Feringa and co-workers used this approach in their design of a molecule that can repeatably perform 360° rotation. The full rotation of this molecular motor takes place in four different stages. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. Basic working principle illustrated Light-driven rotary molecular motors In stages A and C, rotation of the aryl moiety is restricted, although helix inversion is possible. In stages B and D, the aryl can rotate with respect to the naphthalene, however, steric interactions do prevent the aryl from passing the naphthalene. The rotary cycle consists of four chemically induced steps which realize the conversion of one stage into the next. Steps 1 and 3 are asymmetric ring opening reactions which make use of a chiral reagent in order to control the direction of the rotation of the aryl. Steps 2 and 4 consist of the deprotection of the phenol, followed by regioselective ring formation. So far, this molecular motor is the only reported example of a fully chemically driven artificial rotary molecular motor that is capable of 360° rotation. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. Basic working principle illustrated Electron tunneling driven rotary molecular motors ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. Basic working principle illustrated Electron tunneling driven rotary molecular motors As shown in the figure above, one type of motor has a shaft formed by a (12,0) carbon nanotube, which could be fixed into CNT bearings. Three (six) stalks, formed by polymerized iceane molecules with saturated bonds are attached to the shaft at an angle of 120° (60°) with respect to each other. The stalks are chosen to have the length of 2 nm, in order to prevent nonresonant electron tunneling from the blades to the shaft. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. Basic working principle illustrated Electron tunneling driven rotary molecular motors The energies of their electronic states should also prevent the electron transfer along the stalks by resonant tunneling. The blades are formed by molecules with conjugated bonds (fullerenes), covalently attached at the top of the stalks. In principle, such a hybrid molecular rotor could be synthesized by cycloaddition reactions. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. Basic working principle illustrated Molecular propeller ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

19. Basic working principle illustrated Molecular propeller The molecular propellers designed in the group of Prof. Petr Král from the University of Illinois at Chicago have their blades formed by planar aromatic molecules and the shaft is a carbon nanotube. Molecular dynamics simulations show that these propellers can serve as efficient pumps in the bulk and at the surfaces of liquids. Their pumping efficiency depends on the chemistry of the interface between the blades and the liquid. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

20. Basic working principle illustrated Molecular propeller For example, if the blades are hydrophobic, water molecules do not bind to them, due to their little bond polarity, and the propellers can pump them well. If the blades are hydrophilic, water molecules form hydrogen bonds with the atoms in the polar blades. This can largely block the flow of other water molecules around the blades and significantly slow down their pumping. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

21. Basic working principle illustrated Molecular propeller Molecular propellers can be rotated by molecular motors that can be driven by chemical, biological, optical and electrical means or various ratchet-like mechanisms. Nature realizes most biological activities with a large number of highly sophisticated molecular motors, such as myosin, kinesin, and ATP synthase. For example, rotary molecular motors attached to protein-based tails called flagella can propel bacteria. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

22. Limitations • Molecular motors and propellers are in a research and development face hence they are far from commercially useful. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators