Michael Therien, Ph.D., Advisor
As the shrinking size of silicon-based electronic devices approaches the physical limit hindered by quantum tunneling, molecular electronics has gained attention to be a promising candidate to design the individual molecules serving the similar functionality of transitional components. In this regard, the introduction of molecular spintronics where the electron spin degree of freedom is exploited in addition to the charge brings more versatility to superior efficiency in information processing. Crucial to the realization of spintronics is developing molecular spintronic components. This work illustrates electron spin coupling, polarization, propagation, and relaxation behaviors in perylene diimide derivatives, meso-to-meso acetylene-bridged multi[zinc(II) porphyrin] and [copper(II) porphyrin] oligomers. Polyproline-porphyrin complexes were designed as spintronics molecular wires to propagate spin-polarized current measured by spin-dependent Hall devices, demonstrating the importance of employing achiral conjugated wires as low-resistance spintronic wires. Highly conjugated (porphinato)Zn arrays through chirality induction of chiral ligands enable the opportunity in host-guest chemistry to tune chirality as well spin polarization by replacing enantiomeric ligand in molecular layers. Nanodonuts formed by chiral alanine-based perylene diimide were examined to demonstrate the highest rectification ratio resulting from asymmetric molecule-electrode coupling and high spin polarization. Spin dynamics in symmetric, strongly π-conjugated bis[(porphinato)copper] systems were investigated in electron paramagnetic resonance where atom-specific macrocycle spin density, linkage topology, and orbital symmetry play an important role in the magnitudes of electronic spin−spin couplings over substantial Cu−Cu distances. In sum, highly conjugated molecular wires and perylene diimide derivatives can be employed as a spintronic extension cord, wire, diode, and router.
Department of Chemistry