Naphthalene-Attached Luminescent Radicals: Investigation of Position-Dependent Photophysical Properties

Tris(2,4,6-trichlorophenyl)methyl (TTM) radicals substituted at the C1 and C2 positions of naphthalene were synthesized. The C1 substitution led to a broader photoluminescence (PL) spectrum and a significantly lower PL quantum yield (PLQY) compared to the C2 substitution. Density functional theory (DFT) calculations suggested that these differences arise from variations in steric effects and the associated molecular conformation in the excited states. Our results emphasize that the bonding position is crucial for controlling the photophysical properties of acene-substituted TTM radicals.