This new collaborative group award to Jonathan S. Lindsey at North Carolina State University is supported by the Advanced Materials Program in the Chemistry Division, the Electronic Materials Program in the Division of Materials Research and the Office of Multidisciplinary Activities in the Mathematical and Physical Sciences Directorate. The collaboration is between Lindsey and David F. Bocian at the University of California at Riverside and Dewey Holten at Washington University. The expertise of the collaborators spans synthesis, static characterization and dynamic photophysical studies of molecular electronic systems. The focus of the research is the design, synthesis and physical characterization of molecular optoelectronic gates based on multi-porphyrin arrays. The gates are conceptual extensions of molecular wires where the signal transmission can be turned on or off by placement of a magnesium porphyrin moiety which by chemical, electrochemical, or photochemical oxidation opens a channel that funnels excited-state energy to the ground state. These redox-driven molecular gates parallel the operation of transistor switches. The scope of the gating phenomenon, optical gating methods, and and the combination of molecular gates to achieve logic functions will be studied. Static and transient absorption and fluorescence spectroscopy, resonance Raman spectroscopy and electrochemistry will be used to characterize the systems both in solution and as thin films. Time-resolved absorption and fluorescence measurements will be made on the new arrays to elucidate the rates and pathways of energy and electron transfer. This research addresses the fundamental issue of whether molecular electronics are a viable limit in the drive towards computer miniaturization and whether information processing is possible at the molecular scale. The molecular optoelectronic gates which will be prepared will simulate the solid-state transistors in conventional circuitry. If successful, molecular optoelectronic gates may find applications as sensors or as components of other smart structures.
