Canceled: Proposal Defense – Matthew Beckman

About the event

Speaker: Matthew Beckman

Group: Dr. Hipps and Dr. Mazur

Title: Investigating Cooperativity in Axial Ligation Binding of n-mer Zinc-Porphyrin Self-Assembled Monolayers via Scanning Tunneling Microscopy and Computational Methods

Abstract:

Cooperativity is a phenomenon where nonadditive interactions between bodies in a system can increase or decrease the affinity for subsequent interactions. This process is ubiquitous in numerous physical and biological systems, influencing processes such as catalysis, protein folding, adsorption, oxygen binding in the blood, and supramolecular assembly. Despite its ubiquity, the mechanisms and systemic conditions that give rise to cooperative behavior remain poorly understood due to difficulty in its quantitative evaluation, somewhat nebulous definition, and stochastic nature. Scanning Tunneling Microscopy (STM) is a powerful tool for quantitatively evaluate cooperative processes at the nanoscale. Porphyrins and their self-assembled monolayers (SAMs) on surfaces remain an object of tremendous interest to the scientific community, owing to their high degree of synthetic tunability, variable electronic properties, and applications in sensing, molecular electronics, solar cells, and industrial use as dyes. While the intermolecular cooperativity of the axial ligation of small ligands to metal porphyrin monomer SAMs has been previously investigated, the intramolecular cooperativity of porphyrin dimers and trimers remain unexplored. The aims of this proposal are to: (a) characterize a series of novel n-mer metal porphyrin SAMS via STM, (b) Calculate the optimized structures and energies of the adsorbed species via ab initio Density Functional Theory (DFT) calculations and, (c) qualitatively and quantitatively evaluate the cooperative behavior of the axial ligation of 4,4’-Bipyridine and 1-Azabicyclo[2.2.2]octane (ABCO) on the novel n-mer metal porphyrin self-assembled monolayers via STM, ab initio Density Functional Theory calculations, and a novel Grand Canonical Nearest Neighbor Occupation Analysis software. By accomplishing these aims, accurate quantitative measurements and insights into the mechanism of inter- and intramolecular cooperative processes between monomer, dimer, and trimer systems of metal porphyrins at the solution-solid interface can be found. The findings of this proposal will help create a framework to better understand cooperative processes of n-mer metal-porphyrins at the solution-surface interface and provide new insight into how future systems can be designed to leverage cooperative behavior.