Pristine Graphene as a Racemization Catalyst for Axially Chiral BINOL |
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Authors: | Asja A Kroeger Dr Joel F Hooper Prof Amir Karton |
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Institution: | 1. School of Molecular Sciences, The University of Western Australia, Perth, WA, 6009 Australia;2. School of Chemistry, Monash University, Clayton 3800, Victoria, Australia |
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Abstract: | Despite versatile applications of functionalized graphene in catalysis, applications of pure, unfunctionalized graphene in catalysis are in their infancy. This work uses both computational and experimental approaches to show that single-layer graphene can efficiently catalyze the racemization of axially chiral BINOL in solution. Using double-hybrid density functional theory (DHDFT) we calculate the uncatalyzed and catalyzed Gibbs free reaction barrier heights in a number of representative solvents of varying polarity: benzene, diphenyl ether, dimethylformamide (DMF), and water. These calculations show that (i) graphene can achieve significant catalytic efficiencies (▵▵G≠cat) varying between 47.2 (in diphenyl ether) and 60.7 (in DMF) kJ mol−1. An energy decomposition analysis reveals that this catalytic activity is driven by electrostatic and dispersion interactions. Based on these computational results, we explore the graphene-catalyzed racemization of axially chiral BINOL experimentally and show that single-layer graphene can efficiently catalyze this process. Whilst the uncatalyzed racemization requires high temperatures of over 200 °C, a pristine single-layer graphene catalyst makes it accessible at 60 °C. |
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Keywords: | axial chirality dispersion interactions 2D Materials graphene catalysis π-π catalysis |
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