Nondestructive Quantitative Analysis of Lithium Ion-Endohedral Fullerene Salt (Li + @C 60 ·PF 6 – ) via 19 F NMR Spectroscopy

High Resolution Image Download MS PowerPoint Slide A quantitative analysis of the lithium ion-endohedral fullerene salt, Li + @C 60 ·PF 6 – ( 1 ), was performed using 19 F nuclear magnetic resonance (NMR) spectroscopy. To establish a robust quantitative 19 F NMR (qNMR) method, experimental parameters─including spin–lattice relaxation time ( T 1 ), relaxation delay, and offset frequency─were optimized using tetrabutylammonium hexafluorophosphate (TBA + ·PF 6 – ) as a model compound and α,α,α-trifluorotoluene (PhCF 3 ) as an internal standard. The purity of 1 was determined using a calibration curve constructed from 19 F NMR measurements, which effectively minimized systematic errors. The purity value obtained via this nondestructive qNMR method was approximately 95%, showing excellent agreement with quantitative results obtained from inductively coupled plasma atomic emission spectroscopy (95.1%). This method offers a rapid, specific, and nondestructive alternative for the purity evaluation of endohedral metallofullerenes allowing for complete sample recovery.