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STM Investigation of Electric Polar Molecular Self-Assembly and Artificial Electric Polar Molecular Rotors

Zhang, Yuan
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1416927903

Abstract Details

2014, Doctor of Philosophy (PhD), Ohio University, Physics and Astronomy (Arts and Sciences).
This dissertation studies electric polar molecular self-assemblies and artificial electric polar molecular rotors via low temperature ultrahigh vacuum scanning tunneling microscopy. The influence of molecular dipole interaction on two fluorinated sexiphenyl (2F-6P) isomers self-assembly processes is investigated. The slight modification on 6P induces a dipole moment in the molecule and results a completely different assembly structure. Analysis of cluster dipolar energy and atom specific interactions between molecules reveals that fluorinated 2F-6P self-assembly is under more influence of H-F interaction than the dipolar interaction for closer intermolecular distances. A comprehensive study of a double decker molecular rotor [phthalocyaninato-porphyrinato-europium] is conducted on different substrates. Single molecular rotor has its alkyl chains removed after adsorption on Au(111). With thermal energy provided from the substrate, the rotor spins at both ~ 80 K and ~ 5 K surface temperatures. Molecule rotations can be terminated mechanically using a blocker fragment and its rotation can be reinitiated after the removal of this blocker. Single molecular rotor survives rotation during lateral movement under tip manipulation. On Ag(111) surface, the molecular rotors self-assemble into parallelogram clusters. Alkyl chains of the stators are also intact leading to large inter-molecular distances. No cluster rotation is observed in experiments because the dipole interaction energy in a parallelogram network needs to be overcome. On Cu(111), the molecular rotors self-assemble into infinite hexagonal networks, which is the most compact assembly. STM tip provides electrical energy for rotor network to rotate through its electrical field. The dipolar interaction energy between rotors has a degenerate ground state for such rotors network, which makes a synchronized rotation of the network achievable. Synchronized rotation by means of STM lateral manipulation and imaging are observed in large flat areas. Detail analysis of the rotation process reveals that synchronized rotation of the rotors do not propagate into areas close to step edges, and consequently it creates the rotor domains.
Saw-Wai Hla (Advisor)
93 p.
Nanoscience; Nanotechnology; Physics
Artificial Molecular Rotors; Dipolar Molecular Rotors; Molecular Rotor Networks Communication; Dipole Interaction; Low Temperature STM; Molecular Self-Assembly

Recommended Citations

Citations

  • Zhang, Y. (2014). STM Investigation of Electric Polar Molecular Self-Assembly and Artificial Electric Polar Molecular Rotors [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1416927903

    APA Style (7th edition)

  • Zhang, Yuan. STM Investigation of Electric Polar Molecular Self-Assembly and Artificial Electric Polar Molecular Rotors . 2014. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1416927903.

    MLA Style (8th edition)

  • Zhang, Yuan. "STM Investigation of Electric Polar Molecular Self-Assembly and Artificial Electric Polar Molecular Rotors ." Doctoral dissertation, Ohio University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1416927903

    Chicago Manual of Style (17th edition)

ohiou1416927903
524
© 2014, all rights reserved.
This open access ETD is published by Ohio University and OhioLINK.