Characterization of Porphyrin Thiol Assemblies on Au (111)

Abstract

Numerous studies have been conducted using porphyrin molecules on various substrates to investigate their diverse photoelectrochemical, catalytic, electronic, and biochemical properties. These properties make porphyrin molecules targets for use as active components in devices such as chemical sensors, information storage, and photo sensitizers in solar cells. In this study, we investigated the assembly and aggregation of mono-podal zinc (II) porphyrin molecules into a dodecanethiol self-assembled monolayer (SAM) on gold. The porphyrin macrocycle is attached to a phenyl linking group and an alkanethiol tether which binds to the gold surface. The charge transport properties of the porphyrin in confined geometries are being investigated based on previous studies of aggregated assemblies on gold surfaces. In these studies, we find small islands of porphyrins to produce unique electrical switching behavior not observed in single molecules. To explore how island size influences the electrical properties of these compounds, we are investigating ways of creating well defined directed assemblies of controlled nanoscale dimension ranging from 10 to 100 nm in size by Atomic Force Microscopy. This research will facilitate the development of nanoscale and molecularly enhanced devices for applications such as light harvesting or sensing.