Tom Riha

Date Approved

2008

Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department or School

Chemistry

Committee Member

Donald Snyder, PhD, Chair

Committee Member

Timothy Friebe, PhD, Committee Member

Committee Member

Larry Kolopaijlo, PhD, Committee Member

Abstract

Self-assembled monolayers (SAM) of dithiocarbamate ligands were formed on the Au surface of an interdigitated electrode (IDE) array by reaction of amines with CS2 in H2O/CH3OH solutions. Impedance spectroscopy was used to probe for the presence of each SAM as they were individually applied to the surface of the IDE by examining differences in collected impedance data after each step of the chemical application sequence. The impedance behavior of the SAM’s were then studied in the presence of aqueous Cu2+ and Mg2+ ions. A treated IDE array would, in theory, be able to preferentially detect lower concentrations of Cu2+(aq) by complexing with that specific ion, thus concentrating it within the capacitance field. Cupric ion chelating groups anchored to the gold surface by the dithiocarbamate group included morpholine or 5-amino-1,10-phenanthroline. A sensitive determination of the amount of Cu2+ leaching from anti-fouling marine hull coatings into water would be a useful example of practical applications of impedance-based sensors for heavy metal ions. Results of this work indicate that the SAM-treated IDE arrays differed in their impedance behavior relative to untreated IDE arrays. The SAM-treated IDE arrays detected 1.00 μM Cu2+ concentrations with confidence, while untreated IDE arrays only detected as low as 50.0 μM Cu2+ with confidence. ii

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