³He@C₆₀ as a Concise Probe in Complex Systems: Diels‐Alder Reac‐tions of Fullerene with Different Bis Anthracene Compounds

Three bis‐anthracene (BA) compounds, characterized by varying alkyl chain lengths between the two anthracene groups, were synthesized and investigated using 3 He NMR spectroscopy on He@C 60 derivatives. The Diels‐Alder reaction of these BAs with fullerene was comprehensively explored. Findings disclosed that BAs with shorter linkers formed mono‐adducts with 3 He@C 60 at lower concentrations. Conversely, the BA compound with the longest linker ( 1 c ) yielded both mono‐adducts and bis‐para‐adducts with C 60 , marked by a distinct 3 He NMR signal peak for bis‐adducts at −12.84 ppm. Importantly, the versatility of the 3 He@C 60 probe was exemplified in characterizing intricate fullerene reactions that conventionally pose challenges. Theoretical analyses validated reaction products, with computational models substantiating experimental results.