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Modification of Macrocyclic Ligand for Electrocatalytic Small Molecule Reduction

Presenters Name: 
Erin Morrisroe
Co Presenters Name: 
Primary Research Mentor: 
Charles Machan
Secondary Research Mentor: 
Lauren Lieske
12:30 - 1:45
Time of Presentation: 
2019 - 12:30pm to 1:45pm
Newcomb Hall Ballroom
Presentation Type: 
Presentations Academic Category: 
Grant Program Recipient: 
USOAR Program

The activation of abundant small molecules such as dioxygen (O2), dihydrogen (H2), and carbon dioxide (CO2) for green energy applications is an area of chemical research that has been studied for several decades.¹ The challenge in activating these molecules is due to their relative inertness posing significant energetic barriers. One method used to facilitate these reactions, involves electrochemically driving these processes forward with the assistance of an electrocatalysts. However, the major challenge is developing an electrocatalyst that can reduce small molecules at low potentials energy and with high selectivity for one product.² There are notable electrocatalyst that have been successful in these conversions however, they utilize precious and non-abundant metals.³ ⁴ The focus of the research presented is to design an electrocatalyst utilizing earth abundant transition metals that can achieve similar if not better results than its predecessors. In order to achieve this goal, organic ligand frameworks are developed and utilized to assist the metal center with the activation of small molecules.⁵ The work presented here focuses on modifying the macrocyclic ligand cyclen to incorporate a cross-bridge as well as two pendent pyridyl arms to synthesize 4,10-bis(pyridin-2-ylmethyl)-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane (CRpy2).⁶ A series of metalation reactions were performed to synthesize [Co(CRpy2)]3+, [Mn(CRpy2)]3+and [Ni(CRpy2)]2+respectively to create three potential electrocatalysts.⁶ ⁷ These electrocatalysts were electrochemically characterized via cyclic voltammetry (CV) and screened for O2 and CO2 activation.