Honors Theses

Date of Award

Spring 4-14-2021

Document Type

Undergraduate Thesis

Department

Chemistry and Biochemistry

First Advisor

Daniell Mattern

Second Advisor

Susan Pedigo

Third Advisor

Emily Rowland

Relational Format

Dissertation/Thesis

Abstract

Multiple attempts were made to deprotect TBDMS-protected (tert-butyldimethylsilyl protected) serinol and swallowtailed PBI (Compound 2), synthesized by past researcher Tarrah Frederick, to generate Compound 1. The theoretical Compound 1 product is intended for use in molecular rectification of electricity because the perylene core acts as a good acceptor with high electron affinity, and it does not require an electron donor group. Many rectification molecules are amphiphilic Donor-σ-Acceptor compounds, which allow for electron transfer through localized molecular orbitals when placed between electrodes (Langmuir-Blodgett Method). However, PBIs can transfer electrons from one electrode, through the LUMO of perylene, and to the other electrode at specific voltages by asymmetric rectification. Thus, PBIs have been particular molecules of interest as molecular rectifiers with only an acceptor and no donor.5

Several issues arose during the synthesis of Compound 1 and deprotection of Compound 2, such as unknown impurities, byproducts, molecular orientations, intramolecular forces, and other complexities. All of these difficulties resulted in unsuccessful deprotection and ultimately unclear NMR spectra, despite similarly published literature procedures.5 However, the addition of β-alanine to PMA provided a similar, more concise, and more successful method for addition of a polar, hydrophilic group to PMA (Compound 4), though further analysis is needed for confirmation.4 Continued experimentation with deprotection and β-alanine addition was halted after coordination with other research groups retired. More research is needed moving forward to understand the addition and deprotection of groups on PMA and PBI.9

Furthermore, the pursuit of pyrenylcyclohexyl imide (PCHI) group addition to PMA was explored (Compound 3). Synthesis of this group and subsequent addition of it to PMA would progress towards the desired product of the Hammer Proposal (Compound 3),7 which seeks to understand and synthesize unimolecular rectifiers with various carbon tethers on PMA. Numerous difficulties were encountered during synthesis of the PCHI with bromine Grignards. Formation of the perylene Grignard with Br proves quite difficult, so synthesis of this Grignard with iodine was explored instead. Iodopyrene was successfully synthesized3, but the Grignard struggled to form again. Perhaps treatment with butyl lithium offers further investigation of PCHI and the Hammer Proposal.7

All in all, the reactions and methods described in this text provide useful information for synthesis and future investigation of targeted PBI molecules for molecular rectification.

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