Heterogeneous Catalysis by Fullerene C ₆₀ : Photocatalytic Dehydro‐Dimerization of Primary Amines and Tetrahydroquinolines Studied Using Thread Spray Mass Spectrometry

Removal of a catalyst after a catalytic process is a time-consuming and challenging process. In this paper, a fullerene catalyst coated on cellulose thread is developed and applied it in a heterogeneous photoreaction screening via a thread spray mass spectrometry (MS) platform. The surface of the cellulose thread is modified with NH₂ groups, which subsequently allows immobilization of fullerene C₆₀ on the thread. The final fullerene functionalized thread is placed in a glass capillary and the solution of the reactant to be interrogated is added. The assembly of thread and glass capillary is placed in front of a mass spectrometer, which serves as an online photoreaction platform after a light source and direct current high voltage are applied. As an ambient ionization approach, the photocatalytic reaction screening platform enabled real-time MS characterization of products and intermediates and using only nanomole quantities of reactants. Fullerene C₆₀ is identified to facilitate dehydro-dimerization reactions from amines. Norharmane shows a unique photo-oxygenated dimer formation. The functionalized threads immobilized with fullerene C₆₀ are reusable, confirming the heterogeneous nature of the platform. Thus, this system provided real-time screening of reactions catalyzed by fullerene C₆₀ and a means to investigate the reaction mechanism.